He Qing 

High Voltage Electric Vehicles:  

Benefits and Challenges 

Master’s Thesis  

 

 
  

Vaasa 2024 

 
School of Technology and Innovations 

Master of Science in Technology 
Master’s Program in Smart Energy 

 



2 

UNIVERSITY OF VAASA 

School of Innovations and Technology 

Author:    He Qing 

Title of the Thesis:  High Voltage Electric Vehicles : Benefits and challenges  

Degree:    Master of Science in Technology  

Program:   Smart Energy 

Supervisor:   Mustafa Alrayah Hassan Ibraheem  

Year:    2024 Pages: 85 

ABSTRACT : 

Electric vehicles have developed rapidly over the years, because they can reduce carbon 

emissions and slow down the impact of global warming. On the other hand, their higher energy 

efficiency and driving experience have also been favored by many consumers. The electric 

vehicles' (EV) energy efficiency improvement, performance, and the increase of the system 

voltage are the major interest of many automobile manufacturers, which can maintain or reduce 

the system current and increase the motor and charging power. In addition, it has a very positive 

effect on expanding the driving range and charging speed. Compared with the traditional 400V 

system, the 800V high-voltage system has been widely publicized and studied in recent years, 

but the specific performance of these two systems under different driving cycles is rare.  

This thesis aims to provide a comprehensive dynamic performance comparison between the 

400V and 800V EVs system in terms of state of charge (SoC) saving, torque, maxim dc current 

needed, and charging power. This thesis adopts the mainstream commonly used PMSM motor 

and FOC control strategy, configures the basic architecture of electric vehicles, and compares its 

performance in different driving cycles under 400V and 800V systems by increasing the battery 

voltage, to verify the specific performance of 800V systems. 

The thesis findings verified that 800V systems has get better SoC savings comparing to 400V 

systems, especially during high acceleration speed driving scenarios, whereas the most 

prominent benefit is the DC current can be decreased significantly with energy efficiency 

improves. Results also shows the 800V charging system can nearly cut EV battery charging time 

in half when the current is equal with 400V systems. Challenges for implementing 800V system: 

infrastructure hinder, SiC semiconductor industrialize maturity, motor and battery technology 

improvement and future research directions have been concluded and discussed.  

 

KEYWORDS: High voltage, 800V, EV, PMSM, FOC, drive cycle, Battery, Charging, Simulink 



3 

ACKNOWLEDGMENTS  
 

I would like to express my grateful gratitude to my supervisor, Dr. Mustafa Alrayah Hassan 

Ibraheem, for him giving me valuable research directions, key advice and detailed 

guidance throughout the project, while his course inspired me of this research topic, it 

was a real honor to complete this thesis under his guidance.  

 

I would also like to express my sincerest thanks to Prof. Hannu Laaksonen, for allowing 

me to extend my thesis work period when I have medical issues, his support matters a 

lot throughout my master program.  

 

I would also like to express my deepest gratitude to my family for their support and care 

during my studies. Special thanks to my wife Quin, my daughter Rosie, and my friends. 

Thank you for your continued support and encouragement during my studies. 

 

Special thanks to University of Vaasa for giving me the opportunity to participate in this 

master's degree program, I have gained a lot from many courses in the past two years, 

which has laid a good foundation for my future academic and career direction. 

 

 

  



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Contents  

1 Introduction 10 

1.1 Background and problem 10 

1.2 Research Motivation 11 

1.3 Literature Review of Studies on High Voltage BEVs 12 

1.4 Research Questions and Objectives 14 

1.5 Research Methodology 14 

1.6 Research limitations 15 

1.7 Thesis Outline and Structure 15 

2 Electric Architecture of BEV and Charging Solution 16 

2.1 Battery 17 

2.2 Motor, Powertrain and Transmission 20 

2.3 DC-AC Inverter 23 

2.3.1 Controlling of Inverters 25 

2.4 DC-DC Converter 27 

2.5 Battery Charging 29 

2.6 Developing of High Voltage Batteries and Motors 33 

2.6.1 Lighter Weight of Higher Voltage Batteries 35 

2.6.2 High Power of High Voltage Motors 36 

3 Challenges on High-Voltage System Implementation 39 

3.1 Protection for Motor Bearing and Electronic Components. 39 

3.2 Maturity of SiC Semiconductors 40 

3.3 High Requirement to Battery Design and Controlling 40 

3.4 Infrastructure Development and Upgradation 41 

4 Simulink of BEV and Battery Charging 42 

4.1 Battery 43 

4.2 PMSM Motor, Inverter and control. 44 

4.2.1 PMSM Motor and Reducer 44 

4.2.2 Controlling of PMSM 46 



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4.2.3 Inverter 50 

4.3 Vehicle body 51 

4.4 Drive Cycle and Driver 53 

4.5 Simulation of Battery Charging Circuit 55 

5 Simulation Results and Discussion 59 

5.1 India Drive Cycle 63 

5.2 Japanese 10 Mode Drive Cycle 64 

5.3 Specific High Speed Drive Cycle (120Km/h) 65 

5.4 WLTP Class 1 Drive Cycle 66 

5.5 EUDC Drive Cycle 66 

5.6 NEDC Drive Cycle 67 

5.7 China CLTC-P Drive Cycle 68 

5.8 FTP75 Drive Cycle 69 

5.9 Battery Charging 70 

6 Conclusion and Recommendation 74 

7 References 76 

8 Appendices 83 

8.1 Appendix 1. Specific High speed drive cycle data(120Km/h) 83 

  



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Figures  

Figure 1. Vehicle mass reduction of 800V topology VS 400V (Lamm, 2019). ................ 12 

Figure 2. Comparison of charging curve with different charging power (Jung, 2017). .. 13 

Figure 3. Research process flow chart. ........................................................................... 14 

Figure 4. Main components of BEV for the study ........................................................... 15 

Figure 5. Main structure of a BEV ................................................................................... 16 

Figure 6. Different types of battery performance (Tarascon & Armand, 2001) ............. 18 

Figure 7.  Comparisons of different Li-ion batteries (Tarascon & Armand, 2001). ......... 19 

Figure 8. Efficiency comparison for EVs motors. (Aiso & Akatsu, 2022) ......................... 21 

Figure 9 Difference on Motors structures (Cheng, Sun, Buja, & Song, 2015). ............... 22 

Figure 10. Voltage source inverter and current source inverter. .................................... 24 

Figure 11. Inverter inside BEV (Panasonic Industry, 2023) ............................................. 24 

Figure 12. Power loss comparison of Si IGBT and SiC MOSFET (TOSHIBA, 2020)........... 25 

Figure 13. Three types of DC-DC converter (X-engineering, 2015). ............................... 28 

Figure 14. Bi-directional DC-DC converter (X-engineering, 2015). ................................. 28 

Figure 15. A typical full-bridge non-isolated DC-DC converter circuit topology . ........... 29 

Figure 16. AC and DC charging structure in BEV (Blink, 2022). ...................................... 30 

Figure 17. Four levels of BEV Charging. .......................................................................... 31 

Figure 18. Typical DC fast charging curve (EVEsco, 2023). ............................................. 31 

Figure 19. The configuration capable for 800V vehicle charging (EVEsco, 2023)........... 32 

Figure 20. HV battery structure (www.evehicletechnology.com, 2021). ....................... 35 

Figure 21. PMSM motor used on Major Electric Vehicles (MarkLines, n.d.) .................. 38 

Figure 22. Overview of the BEV model main sub-system............................................... 43 

Figure 23. Model of Permanent magnet synchronous motor from Simulink ................ 46 

Figure 24. FOC Control diagram of PMSM ...................................................................... 47 

Figure 25. FOC control algorithm in Simulink. ................................................................ 49 

Figure 26. regenerative braking control logic in Simulink. ............................................. 50 

Figure 27. Inverter module from Simulink...................................................................... 51 

Figure 28. Simulation of vehicle body in Simulink .......................................................... 52 

Figure 29. Drive cycle of NEDC. ...................................................................................... 53 



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Figure 30. Driver model from Simulink. .......................................................................... 54 

Figure 31. CC and CV charging mode for battery. ........................................................... 55 

Figure 32. Battery DC fast charging controlling flow. ..................................................... 56 

Figure 33. Charging controlling algorithm. ..................................................................... 57 

Figure 34. BEV battery DC charging Simulink. ................................................................ 58 

Figure 35. SoC comparison of 400V and 800V system after drive cycles. ...................... 59 

Figure 36. Max. DC current on 400V system VS 800V system. ....................................... 61 

Figure 37. SoC saving difference VS Driving distance(Km). ............................................ 61 

Figure 38. SoC saving difference VS acceleration speed. ............................................... 62 

Figure 39. SoC saving difference VS Top Speed. ............................................................. 63 

Figure 40. Waveform of 400V and 800V system in India Drive cycle. ............................ 64 

Figure 41. Waveform of 400V and 800V system in Japanese 10 mode drive cycle. ...... 65 

Figure 42. Waveform of 400V and 800V system in specific high speed drive cycle. ...... 65 

Figure 43. Waveform of 400V and 800V system in WLTP class 1 drive cycle. ................ 66 

Figure 44. Waveform of 400V and 800V system in EUDC drive cycle. ........................... 67 

Figure 45. Waveform of 400V and 800V system in NEDC drive cycle. ........................... 68 

Figure 46. Waveform of 400V and 800V system in CLTC-P drive cycle. .......................... 69 

Figure 47. Waveform of 400V and 800V system in FTP75 drive cycle. ........................... 70 

Figure 48. Battery charging duration VS charging power. .............................................. 71 

Figure 49. DC charging with 466V,300A for 400V battery. ............................................. 71 

Figure 50. DC charging with 940V, 150A for 800V battery. ............................................ 72 

Figure 51. DC charging with 1000V, 300A for 800V battery. .......................................... 72 

Figure 52. DC charging with 1000V, 350A for 800V battery. .......................................... 73 

 
 
 
 
 
 
 
 
 
 
 



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Tables  
 
Table 1. Comparison of three types of electric motors (Cao, Mahmoudi, Kahourzade, & 

W. L. Soong, 2021). ......................................................................................................... 21 

Table 2. Motor type used on typical BEVs on the current market.................................. 23 

Table 3. Battery parameters setting. .............................................................................. 44 

Table 4. BEV vehicle body parameter. ............................................................................ 53 

Table 5. Features of different driving cycles. .................................................................. 54 

Table 6. Charging parameters for 400V and 800V battery ............................................. 58 

Table 7. SoC changes after different drive cycles (initial state of charge 80%) .............. 59 

Table 8. Max. DC current at different drive cycles. ......................................................... 60 

Table 9. Charging data summary of 400V and 800V charging voltage (40Kwh battery). 70 

 
  



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Abbreviations 
 
BEV    Battery Electric Vehicle 

DC    Direct Current  

AC    Alternating Current 

KWH    Kilowatt-hour 

Ah    Ampere-hour  

SiC    Silicon Carbide 

IGBT    Insulated Gate Bipolar Transistor  

MOSFET   Metal Oxide Semiconductor Field Effect Transistor 

PMSM   Permanent Magnet Synchronous Motor  

IM    Induction Motor 

SRM    Switched Reluctance Motor  

ICE    Internal combustion Engine 

PMW    Pulse Width Modulation  

FOC    Field Orientated control  

OEM    Original Equipment Manufacturer 

PDU    Power Distribution Unit 

EMC    Electro Magnetic Compatibility 

SoC    State of Charge 

SVPWM   Space Vector Pulse Width Modulation  

WLTP    Worldwide Harmonized Light Vehicle Test Procedure 

EUDC     Extra Urban Driving Cycle 

NEDC    New European Driving Cycle  

CLTC    China Light-duty Vehicle Test Cycle 

CC    Constant Current 

CV    Constant Voltage  

 

 
 
  



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1 Introduction 

1.1 Background and problem  

This chapter gives an overview of the thesis topic, discusses the problem, objectives, 

motivation and research methods chosen for the study and outlining the structure. Also, 

an introduction to the basics of electric vehicles is reviewed, briefing the background for 

the thesis's importance.  

 

Climate change and global warming are driving the automotive industry to change to 

new energy, especially electric vehicles are becoming more and more people's choice. 

Governments and research institutions in various countries are also encouraging 

research and development of more efficient and energy-saving solutions to improve the 

competitiveness and attractiveness of electric vehicles (Liao, Molin, & van Wee, 2016). 

 

At present, there are four types of new energy vehicles (HASAN & ISLAM, 2022): hybrid 

electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), fuel cell electric vehicles 

(FCEV) and pure battery electric vehicles (BEV). This paper focuses on the characteristics 

of BEV. BEVs do not produce vehicle exhaust emissions and significantly reduce harmful 

pollutants such as carbon dioxide (CO2) and nitrogen oxides (NOx) compared to 

conventional vehicles. They reduce dependence on fossil fuels, contribute to enhanced 

energy security, and promote technological innovation. In addition, the development of 

BEVs can stimulate economic growth by creating new industries and jobs in areas such 

as renewable energy, battery manufacturing, and infrastructure. 

 

After about 10 years of rapid development, BEVs have gradually occupied 24% market 

shares till middle of 2024 in 15 major regions (Marklines, 2024), and the range and 

charging speed have been greatly improved compared with the earlier versions. At 

present, most of the BEV architecture is a 400V system, and the corresponding DC fast 

charging ports are also 400V. 



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The maximum charging power of the 400V charging is limited to around 100KW (with 

current 250A). For an electric vehicle equipped with a 100kwh battery, it takes at least 

30 minutes to charge from 30% to 80%. The charging speed is still not at a similar level 

as the refueling speed of traditional cars and which is hindering people’s favor on BEVs. 

Moreover, the battery power and energy efficiency of electric vehicles are desired to be 

lifted higher and higher to save the energy and extend the mileage.  

 

1.2 Research Motivation 

It is said that lifting the voltage architecture of BEV to 800V can improve this situation.  

According to the formula of power calculation, where P is charging power, V is voltage 

and A is the current value:  

 𝑃 = 𝑉 × 𝐴        (1) 

 

Assuming that the charging pile power is 125KW, when the 400V electric vehicle is 

charged, max current will be 312.5 A, which exceeds the rated value of the 250A cable 

(Bonnen Battery, 2023), the charging power at this time is limited to 100kW, which 

cannot fully utilize the 125kW charging station, and when lifting the voltage to 800V,  

max. current will be 156.25 A, with a cable current rating of less than 250A, the vehicle 

can fully utilize the 125kW charging power.  

 

In this case, when an electric vehicle with a 100kWh battery, needs 30 minutes to charge 

30% to 80% under the current 400V voltage platform and 250A current, it would only 

need about 15 minutes if the voltage is raised to about 800V, and even faster if extend 

the current limitation, and this is almost close to the refueling speed of ICE vehicles.  

 

The mileage of the 400V BEV architecture is currently maintained at around 600Km 

(Electric vehicle database, 2023), and the charging speed is about 100KW, which cannot 

eliminate the range anxiety of consumers. At the same time, for developers, the energy 

consumption of the 400V system still has room for compression, for the 100KWH battery, 



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the weight of the vehicle is about 2 tons (EVbox, Electric car battery weight explained, 

2023), while the traditional fuel vehicle is generally about 1.5 tons, the overweight body 

limits the further improvement of the mileage. 

 

The 800V BEV architecture can improve this situation to a certain extent, for example, it 

increases the charging speed, which can greatly shorten the waiting time for charging, 

and at the same time, the energy loss due to heat loss from lower current on drivetrain 

system is reduced, and the weight of the vehicle is also reduced, which benefit to 

improve the range of the BEV. 

 

1.3 Literature Review of Studies on High Voltage BEVs 

According to research by (Lamm, 2019), high voltage will reduce the vehicle mass 

especially in battery. Copper is used as a key material for wiring , motors and battery 

high-voltage busbars in electric vehicles, according to statistics (Copper Development 

Association INC, 2022), the amount of copper used in a 100KWH BEV is about 80KG, 

which is equivalent to 4% of the vehicle weight. By increasing the vehicle voltage from 

400V to 800V, the current is reduced, the wiring and high-voltage busbar are reduced 

(Jung, 2017), and the whole vehicle is reduced, the weight of electric vehicles with 800V 

architecture can be reduced by more than 25KG (Lamm, 2019), as shown in Figure 1.  

 

 

Figure 1. Vehicle mass reduction of 800V topology VS 400V (Lamm, 2019). 

 



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With small current, the wires diameters can be reduced, the amount of copper used is 

then reduced, therefore weight of the whole vehicle is also reduced accordingly. 

 

In research (Jung, 2017), Jung indicated that the DC charging power will be limited 

between 50KW – 150KW under 400V system, while it can be increased to max. 350KW 

if charging system voltage increases to 800V.  It takes 30mins to charge a 415V battery 

with 150KW, while it only takes approx. 10mins to charge with 350KW, as shown in Figure 

2.  

 

 

Figure 2. Comparison of charging curve with different charging power (Jung, 2017). 

 

In addition, the 800V architecture can use SiC MOSFETs instead of Si IGBTs as vehicle 

power semiconductors, and its losses in the full load range are lower than those of Si 

IGBTs, and the losses can be reduced by 80% in the normal use range of vehicles, which 

makes the energy efficiency of SiC high-voltage architecture vehicles about 3.5~8% 

higher than that of 400V vehicles (Shi, et al., 2023). Study (Allca-Pekarovic, et al., 2024) 

also shows that BEV’s range can increase about 5% under 800V with EPA drive cycles.  

 



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1.4 Research Questions and Objectives  

The main research questions of this paper are to study the charging rate, energy 

consumption of BEVs under the 800V high-voltage architecture, and compare with 400V 

systems to verify their advantages and limitations, to find out the energy consumption 

characteristics and charging speed of them. Main objectives of this thesis is to research 

about detail designing of BEV drivetrain system, simulate its performance at the two 

voltage levels (400V & 800V). Charging systems at two voltage levels will also be 

investigated and simulated for comparing the charging speed.  

 

1.5 Research Methodology  

The research methodology is carried on as listed in Figure 3, by simulate the BEV 

electronic structure in MATLAB Simulink, selecting the PMSM motor with FOC control 

method, together with lithium-ion Battery, IGBT inverter and the typical 4-wheel vehicle 

body, run the simulation with different drive cycles, as shown in Figure 4. Battery 

charging is simulated with DC fast charging method in CC (Constant Current) and CV 

(Constant Voltage) at different phases.   

 

 

Figure 3. Research process flow chart. 

 



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Figure 4. Main components of BEV for the study. 

 

1.6 Research limitations  

This thesis focuses on energy efficiency evaluation, and charging speed between 400V 

and 800V electric vehicle architectures, using the basic structure of BEV and charging 

electronic circuits, which do not consider complex level of power aspects, such as low 

voltage (48V, 24V or 12V) accessories, high level motor controlling strategies, 

regenerative breaking power charging, thermal management and different level braking 

controlling for passenger comfort, etc. Therefore, the results only indicate the general 

trend under the technology but may not for very accurate verifications.    

 

1.7 Thesis Outline and Structure  

The thesis is organized as follows: Chapter 2 discusses the development of BEV electric 

architectures and review the details of each sub-system. As well as literature review 

about the challenges on current technology application and the future developing trend. 

After that, in Chapter 3, the main sub-systems of BEV and charging circuit are simulated 

in MATLAB Simulink. In Chapter 4, the results of simulations under different cases are 

listed and reviewed. Finally, Chapter 5 concludes the thesis, discussing the results and 

suggesting future research recommendations. 

  



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2 Electric Architecture of BEV and Charging Solution 

This chapter discusses the main structure of BEV, including Battery, DC-DC converter, DC-

AC inverter, Motor, vehicle body as Figure 5 illustrates, and Charge circuits, including 

their functions and development trends.  

 

 

Figure 5. Main structure of a BEV. 

 

The first electric car was developed in the early 1900s (Wikipedia, 2024), although it was 

far from the electric cars of today. Since then, they have become critical components for 

a more sustainable society, despite having to surpass engineering challenges. The range, 

performance (acceleration and high speed), and battery sustainability of these BEVs is 

still being questioned by consumers today, despite many electric cars having an 

acceleration speed of 4.x seconds up to 100km/h, while max. speed kept around 

200km/h. Meanwhile, with fast upgrading development of batteries, the range of BEVs 

could now easily reach 500+ km with battery volume over 80 KWH. World car 

manufacturers are racing into the competition of BEVs while new gamers pop into the 

market with Highly competitive products, such as Tesla, BYD. To maintain and gain the 

market shares, they rush into the developing of high efficiency, good power density 

structures, and fast charging solutions which suit better for consumers’ decrement 

(Aghabali, Kollmeyer, & Bilgin, 800-V Electric Vehicle Powertrains: Review and Analysis 

of Benefits, Challenges and Future Trends, 2021).  

 



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BEVs are powered by electric motors which are fueled by rechargeable batteries. The 

core structure of a BEV contains several key components: battery pack, electric motor, 

reducer, power electronics and charging system. Like ICE to traditional vehicles, electric 

motors are the heart to BEVs.  

 

2.1 Battery  

At present, lithium batteries are widely used on high performance BEVs, and it’s most 

common types are, ternary lithium battery and lithium iron phosphate battery, both of 

which belong to lithium-ion batteries, the difference lies in the difference in cathode 

materials (Pesaran, 2023). 

• Ternary lithium battery refers to the cathode material of lithium nickel cobalt 

manganese oxide (Li (NiCoMn)O2), which is made of nickel salt, cobalt salt and 

manganese salt, and the proportion of nickel, cobalt and manganese can be 

adjusted according to actual needs. The advantage of ternary lithium battery 

energy is it’s dense, and the battery of the same weight can provide a longer 

cruising range for the vehicle (Yepeng Wang, 2022). 

• Lithium iron phosphate batteries are more stable than ternary materials. Its 

manufacturing cost is lower than ternary lithium batteries, it can be charged 

quickly and has a long cycle life, and its operating temperature range is also wider. 

However, the disadvantage is its energy density is much lower than ternary 

lithium batteries, and its attenuation is worse in low temperature environments 

(Tredeau & Salameh, 2009). Although lithium iron phosphate batteries have 

lower energy than ternary lithium batteries under the same weight, they are 

better in terms of low cost and high safety (Rahul Rao, 2021). 

   

There are also other types of Lithium batteries, such as Lithium cobalt oxide battery (Wu, 

Zhang, & Lu, 2022), which was used on early version of Tesla Model S BEVs. However, 

the manufacturing cost of lithium cobalt oxide batteries is high and there is a certain 

pollution to the environment, which were gradually abandoned. NiMH battery is also a 

green and environmentally friendly battery with the advantages of high energy density 



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and long life. It is mainly used in hybrid vehicles such as the Toyota Prius and the Ford 

Escape. However, nickel-metal hydride batteries are expensive to manufacture and 

relatively slow to charge (Ying, Gao, Hu, Wu, & Noréus, 2006). 

 

Below Figure 6 utilizes the characteristics of different batteries materials on the energy 

density and weight (Tarascon & Armand, 2001).  

 

 

Figure 6. Different types of battery performance (Tarascon & Armand, 2001) 

 

Figure 7 compares the general characteristics and performance of different types of Li-

ion batteries as listed below, which illustrate that LFP and NMC are delivering most 

balanced capabilities on all aspects, while NMC has better energy capacities, LFP has 

better performance and life-span and safety (Tarascon & Armand, 2001), the type of 

battery names listed as below:  

• Lithium Cobalt Oxide (LiCoO2)  

• Lithium Manganese Oxide (LMO) 

• Lithium Iron Phosphate (LFP) 

• Lithium Nickel Manganese Cobalt Oxide (NMC) 

• Lithium Nickel Cobalt Aluminum Oxide (NCA) 



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• Lithium Titanate (LTO) 

 

 

Figure 7.  Comparisons of different Li-ion batteries (Tarascon & Armand, 2001). 

 

There are also other types of batteries under research and fast developing, including 

Solid-state batteries and Graphene batteries. The biggest difference between solid-state 

batteries and the current mainstream traditional lithium-ion batteries is the electrolyte 

(Liu, et al., 2024). Solid-state batteries use solid electrolytes to replace the electrolyte 

and separator of traditional lithium-ion batteries to achieve a higher density battery 

capacity, and some data show that the volume energy density of solid-state batteries can 

be increased by more than 70% compared with liquid lithium batteries, reaching 

500Wh/kg (Bates, et al., 2022). At the same time, solid-state batteries can also greatly 

reduce the risk of thermal runaway and have higher safety attributes (Yu, Chen, Gan, Li, 

& Liquan Chen, 2023). Graphene battery uses two conductive plates coated in a porous 

material and immersed in an electrolyte solution, which has advantages of ultra-high 

energy density, long life, and fast charging (Li, Tang, Wang, Zhou, & Linwei Sai, 2024). At 

present, the specific application of graphene batteries is still in the research and 

development stage, and no specific models have been announced. However, due to the 

huge potential of graphene batteries, it has become a research hotspot in the global 

electric vehicle industry. 



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2.2 Motor, Powertrain and Transmission   

Electric motors offer instant torque delivery, providing smooth and responsive 

acceleration from a standstill. This characteristic is one of the key advantages of electric 

propulsion systems, offering impressive performance metrics compared to traditional 

ICE vehicles. They are generally more compact and lightweight than traditional ICEs, 

allowing for greater flexibility in vehicle design and packaging. This enables automakers 

to optimize interior space and improve overall vehicle dynamics. They are also more 

efficient because of their high transition rate of electrical energy into mechanical power 

(BAI & Sealy, 2023). Electric motors in BEVs can also function as generators during 

deceleration, converting kinetic energy back into electrical energy and storing it in the 

battery. This regenerative braking system helps improve overall efficiency and extends 

the vehicle's range. 

 

There are many divisions of electric motors used on BEVs. Such as AC motors and DC 

motors, permanent motors, and induction motors, etc. There are mainly three types of 

motors are widely used on current BEV’s:  

(1) Permanent magnetic synchronous motors (PMSMs) are most used because of 

their excellent efficiency, power density, and torque characteristics. These 

motors feature permanent magnets embedded in the rotor, providing strong 

magnetic fields and efficient power conversion.  

(2) Induction Motors (IMs) are also a good choice, with the appropriate design and 

control strategies, while they don’t require rare earth materials. IMs offer robust 

performance and reliability, making them also a good solution for certain high-

speed BEV applications.  

(3) Switch reluctance motors (SRMs) utilize the magnetic reluctance principle to 

generate torque and propulsion. Although less common in the automotive 

industry, SRMs can achieve high speeds and offer benefits such as simple 

construction, high reliability, and fault tolerance. 

 



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According to the research (Aiso & Akatsu, 2022), three types of electric motors for 

electric vehicle are evaluated while delivering 85KW power, and shows that PMSM act 

with most high efficiency at both low speed and high speed other than the other two 

types (SRM and IM) as shown in Figure 8.  

 

 

Figure 8. Efficiency comparison for EVs motors. (Aiso & Akatsu, 2022) 

 

A comparison of other characteristics of the three types of electric motors have also 

been studied and reviewed in the paper (Cao, Mahmoudi, Kahourzade, & W. L. Soong, 

2021), and concluded that PMSM has better performance on high speed and torque 

while IM has advantages on wide range, as shown in Table 1. 

 

Table 1. Comparison of three types of electric motors (Cao, Mahmoudi, Kahourzade, & W. L. 

Soong, 2021). 

 PMSM SRM IM 

High speed Good Good  Good  

High torque Good Poor  Medium  

Torque linearity  Good  Poor  Poor  

Power-weight ratio Good  Medium  Medium  

Wide range Poor  Medium  Good  

Low torque ripple Medium  Poor  Good  

 

60%

65%

70%

75%

80%

85%

90%

95%

100%

IM SRM PMSM

Motor efficiency 



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The structures of IM, SRM and PMSM are simply illustrated as in Figure 9. The stator in 

an IM features a laminated iron core with three-phase AC windings that create a rotating 

magnetic field, while its rotor can be either a squirrel-cage type with conductive bars or 

a wound type connected to slip rings, relying on induced current for rotation. In SRM, 

the stator has salient poles with concentrated windings that are sequentially energized 

to create magnetic pull, and the rotor is made of laminated soft magnetic material with 

salient poles but no windings or magnets, moving to align with the stator poles. The 

PMSM has a stator like the IM with a laminated iron core and three-phase AC windings, 

but its rotor contains embedded or surface-mounted permanent magnets, allowing it to 

rotate synchronously with the stator's magnetic field. 

 

 

Figure 9 Difference on Motors structures (Cheng, Sun, Buja, & Song, 2015). 

 

Reflection from the market, the PMSM also are widely used as traction motor on electric 

vehicles as shown in Table 2 for passenger cars (Krings & Monissen, 2020) , (López, Ibarra, 

Matallana, Andreu, & Kortabarria, 2019), because of its high efficiency and high-power 

density. However, due to the rare earth material and high cost, some OEMs such as Tesla 

are also choosing IM for their high performance BEVs. Others are also developing the 

SRM solutions, as it is believed that with low manufacturing cost can deliver higher 

power (Kohei & Kan, 2020).  

 

 

 

 



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Table 2. Motor type used on typical BEVs on the current market. 

Vehicle  Motor type  Max. speed (rpm) Power (KW) 

BMW i3 PMSM 11400 127 

Tesla Model 3 PMSM 18100 202 

Jaguar I-Pace PMSM 13000 147 

Chevy bolt IM 8810 150 

Tesla model S IM 16000 193 

 

This paper selects AC permanent magnet synchronous motor which was widely used on 

current BEVs as the tractor motor for the EV simulation.  

 

The Transmission model controls the vehicle’s shifting requirements throughout gear 

change, as Motors normally have higher nominal working speed, so transmission is also 

treated as reducer on BEVs. It shifts torque from the motor model and braking force into 

front and rear traction forces from driver model. BEV transmissions typically only have 

one gear reductions between the motor and the wheels for both forward and reverse 

motion. In comparison with internal combustion engines, which require multiple gear 

ratios to provide the optimal torque at any given speed, BEVs offer better acceleration 

for a lighter weight package. Normally the gear ratio is fixed depending on the motor 

characteristics. The angular velocity of the follower shaft is dividing the ratio with the 

angular velocity of the input. The follower shaft torque is multiple the input shaft torque.  

 

2.3 DC-AC Inverter  

An inverter is a device that converts DC into AC at an adjustable frequency. As the battery 

is supply electricity in DC, while high power electric motors widely used on BEVs are AC 

motors, therefore, a DC-AC inverter is needed.  

The working principle of the inverter is based on the turn-on and turn-off of 

semiconductor switches (such as transistors, MOSFETs, IGBTs, etc.), which are switched 

at a specific frequency and sequence under the precise control of the control circuit, thus 

realizing the conversion of direct current to alternating current. Inverters can be 

categorized in many ways, such as voltage type and current type as shown in Figure 10.  



24 

Voltage-type PWM inverters are mostly used on electric vehicles (Sambhavi & 

Vijayapriya Ramachandran, 2023). 

 

 

Figure 10. Voltage source inverter and current source inverter. 

 

The main functions of the inverters in the BEVs include three parts: convert the direct 

current of the battery into three-phase alternating current to drive the motor, change 

the torque and speed of the motor by changing the voltage and frequency through the 

inverter, and convert the mechanical energy into electrical energy to charge the battery 

during regenerative braking, as shown in Figure 11.  

 

 

Figure 11. Inverter inside BEV (Panasonic Industry, 2023). 

 



25 

The power module is operated as a switchgear in response to the drive signal while IGBT 

is normally used due to its high switching capabilities. It can operate at high currents and 

speeds to meet the high-performance requirements of vehicles. Currently, there is a 

trend to gradually switch from IGBT to SiC in high-voltage architecture models, which are 

mainly used in systems above 650V. This is because Si MOSFETs and IGBTs have lower 

efficiency and performance compared to SiC-based Wide Bandgap devices (Alves, 

Gomes, Lefranc, Pegado, & Jeannin, 2017). SiC offers higher electric field breakdown 

capability, better thermal conductivity, higher temperature operation capability, and 

higher switching frequencies due to the wider electronic bandgap, resulting in lower 

losses than silicon-based semiconductor devices. SiC materials also minimize switching 

losses of approx. 66% (TOSHIBA, 2020), as shown in Figure 12.  

 

 

Figure 12. Power loss comparison of Si IGBT and SiC MOSFET (TOSHIBA, 2020). 

 

2.3.1 Controlling of Inverters  

The main controlling method used on PMSM controlling are the early constant voltage 

frequency ratio control, the current commonly used direct torque control, vector control 



26 

and other in developing intelligent control. FOC (Field Oriented Control) control 

technology as typical Vector controlling method, is a PMSM motor control technology 

widely used in electric vehicles. FOC control technology realizes efficient and high-

performance operation of the motor by accurately controlling the stator current and 

rotor position of the motor. In electric vehicles, FOC control technology can effectively 

improve the range, efficiency and power density of electric vehicles. 

They are mainly used in typical double-ring motor control systems, which generally 

contain so-called "current loops" and "speed loops". Some of the important modules are 

mathematical modules such as the "Clark Transform" and "Park Transform", a module 

for detecting motor current signals, and modules that provide information about the 

rotational speed and angular position of the motor. 

 

When the electric vehicle performs regenerative braking, the working direction of the 

inverter is reversed, and it converts the alternating current generated by the electric 

motor into direct current and feeds it back to the battery. The vehicle slows down when 

the driver presses the brake pedal or releases the accelerator pedal. At this time, the 

electric motor no longer consumes electrical energy to propel the vehicle but drives the 

motor to rotate through the inertia of the wheels, so that it works in power generation 

mode, converting mechanical energy into alternating current. The frequency and voltage 

of this alternating current depends on the speed and load of the motor. The rectifier 

circuit in the inverter converts the alternating current generated by the motor into direct 

current. This process is the opposite of the inverter process when an electric motor is 

driven, and a device such as a diode or IGBT (insulated gate bipolar transistor) is usually 

used to achieve rectification. The rectified direct current is fed back to the battery 

through the control of the inverter. In this process, the inverter needs to precisely control 

the magnitude and direction of the current to prevent damage to the battery. In addition, 

the inverter needs to monitor the status of the battery, such as voltage and temperature, 

to ensure the safety and efficiency of energy regeneration. 

 



27 

A typical inverter structure consists of the following components: switching device (e.g. 

IGBT), Bridge circuit, gate driver circuit, control circuit, filter, voltage measurement 

module, current measurement module, protection circuit and cooling circuit 

(Barzegarkhoo, Farhangi, Lee, Siwakoti, & Frede Blaabjerg, 2024). 

 

2.4 DC-DC Converter 

A DC-DC converter is an electrical device which converts DC sources from one voltage 

level to another. DC/DC converter, as an important part of the electric power system in 

BEV, the main function of it is converting the low voltage power such as 12V, 24V or 48V, 

for power steering systems, air conditioning and other auxiliary equipment. The other 

role is in the composite power supply system in the charging station, which is connected 

in series with supercapacitors to regulate the power output and stabilize the bus voltage 

(Bellur & Kazimierczuk, 2007). 

 

Generally, there are three types of DC-DC converters, non-isolated, isolated, and 

bidirectional ones. The most popular non-isolated DC-DC converter types are shown in 

Figure 13, the first one is Buck DC-DC converter, which mainly converts high voltage to 

low voltage (and will increase the current at the same time). In automotive applications, 

step-down DC-DC converters are used to reduce the high voltage of the main battery 

(e.g., 400 V) to the lower value (12-14 V) required for vehicle assistance systems 

(multimedia, navigation, radio, lightning, sensors, etc.). The second one is Boost DC-DC 

Converter, which can increase the output voltage while decreasing the output current. 

In some hybrid electric vehicle (HEV) applications, step-up DC-DC converters are used to 

boost the voltage from the battery, such as from 202 V to 500 V. The third one is Buck-

Boost DC-DC converter which can increase or decrease voltage based on the needs of 

the circuit. The buck-boost converter’s output voltage is determined by the input voltage, 

duty cycle, and switching interval, illustrating how changes in duty cycle directly impact 

the voltage output (Khan, Nag, Das, & Yoon, 2021).  

 



28 

 

Figure 13. Three types of DC-DC converter (X-engineering, 2015).  

 

The type of converter which is commonly used on electric vehicles are bidirectional DC-

DC converters. The topology of a non-isolated bidirectional DC-DC converter is shown in 

Figure 14 below. When the battery pack supplies power to the motor, the bidirectional 

DC-DC converter becomes the Boost converter, which increases the voltage of the 

battery pack to provide a stable DC voltage to the inverter and reduces the current ripple 

of the motor. When the motor is in regenerative braking state, the non-isolated 

bidirectional DC-DC converter becomes a buck converter, which steps down the DC 

voltage on the inverter side to safely charge the battery pack. In normal operation, only 

one switch operates at a time between the two power devices of a bidirectional half-

bridge converter.  

 

 

Figure 14. Bi-directional DC-DC converter (X-engineering, 2015). 

 



29 

Adding a high-frequency transformer to a non-isolated bidirectional DC-DC converter 

can turn it into an isolated bidirectional DC-DC converter, and the circuit topology on 

both sides of the high-frequency transformer can be full-bridge, half-bridge, push-pull 

and so on. A typical full-bridge non-isolated DC-DC converter circuit topology (Lüthje, 

Zhang, Carmen, & Andersen, 2018) is shown as in Figure 15. When the energy flows from 

the high-voltage side to the low-voltage side, the bidirectional DC-DC converter operates 

in BUCK mode; When energy flows from the low-voltage side to the high-voltage side, 

the bidirectional dc-dc converter operates in BOOST mode. These isolated bidirectional 

DC-DC converters use more power switches, which makes them have the advantages of 

large voltage conversion ratio and galvanic isolation (Singh, Chaudhari, Sekhar, & Kumar, 

2023 ). Therefore, they have advantages over isolated ones for use in electric vehicles, 

especially in charging solutions.  

 

 

Figure 15. A typical full-bridge non-isolated DC-DC converter circuit topology . 

 

 

2.5 Battery Charging   

The charging system includes DC charging port and AC charging port. The DC charging 

port is a fast-charging interface, which uses high-voltage direct current, and can be 

directly delivered to the power battery through the PDU for charging without processing. 

The AC charging port is a slow charging interface, which uses high-voltage alternating 

current, which needs to be converted into high-voltage direct current through the On-



30 

Board Charger (OBC) unit and then charged the power battery through the PDU (EVbox, 

EV charging: the difference between AC and DC, 2023). The connection between the fast 

and slow charging system and the PDU is shown below in Figure 16. 

 

 

Figure 16. AC and DC charging structure in BEV (Blink, 2022). 

 

The time difference between AC charging and DC fast charging is huge. AC Level 1 

charging has a power output of up to 1.4 kW at 12A and 120VAC, while AC Level 2 

charging can deliver up to 19.2 kW at 80A and 240V. Theoretically, even with the 

maximum power level of 19.2 kW AC charging, it would take about five to six hours to 

fully charge a 100-kWh battery pack. In comparison, with 500A and 400VDC DC fast 

charging, the same 100kWh battery would theoretically take about 30 minutes to reach 

full capacity, as shown in Figure 17. Charging times will be further reduced as battery 

technology advances, 800V architecture upgrades, and charging infrastructure improves. 



31 

 

Figure 17. Four levels of BEV Charging.  

 

DC fast charging is the charging method especially used at commercial public charging 

stations. These charging stations convert AC from the grid to DC. When the owner 

charges an electric vehicle, the DC flows directly to the battery. According to the J1772 

standard, the charging current ranges to max. 500A.  A typical charging speed curve is 

illustrated in Figure 18 below, which the charging speed jumps quickly to top speed in 

the start periods and keeps in high-speed level until SoC reaches 80%.   

 

Figure 18. Typical DC fast charging curve (EVEsco, 2023). 

 



32 

As the number of BEV increases, so does the need to create more energy-efficient 

charging infrastructure systems that can be used to charge vehicles faster, as shown on 

below Figure 19, which the max. charging speed can be realized only when charging 

station and BEV architectures both meet the Max. charging power capacity.  

 

 

Figure 19. The configuration capable for 800V vehicle charging (EVEsco, 2023). 

 

With a higher driving range and larger battery capacity than previous BEVs, there is a 

need to develop fast DC charging solutions to meet fast charging requirements. It is 

calculated that a 150 kW or 200 kW charging station takes about 30 minutes to charge 

an electric car to 80% for a range of about 250 km (Electrify News, 2023). According to 

the combined charging system and the most advanced technology, the super-fast DC 

charging station can provide up to 500 kW of power (Kane, 2023). These super-fast 

charging stations are working with high voltages to control the current output. High-

voltage semiconductor switches (insulated-gate bipolar transistors [IGBTs] and silicon 

carbide [SiC]) are driving the bus voltage to high levels (800 V or 1,000 V) in the system.   



33 

2.6 Developing of High Voltage Batteries and Motors  

The sales of electric vehicles are growing globally (IEA, 2024), consumers are expecting 

better performance on both driving and charging, longer range and faster charging are 

among their demands (Furcher, Giraldo, Rupalla, & Smith, 2023), and both boil down to 

the battery. There is numerous research projects focused on solving these challenges, 

but the most promising one is increasing the battery voltage (Engineering, 2023). Higher 

battery voltage means more energy and higher charging power, plus increased efficiency, 

better performance, and weight savings for BEV components such as motors and 

inverters. 

 

The architecture of a BEV is a sophisticated system comprising batteries, motors, sensors, 

electronic controls, auxiliary equipment, wiring, and various other components. The 

battery voltage, whether 400 volts or 800 volts, significantly influences the design and 

operation of all these elements. Typically, a battery voltage range of 300 to 500 volts is 

classified as a 400-volt architecture, while a range of 600 to 900 volts corresponds to an 

800-volt architecture. Transitioning to an 800-volt architecture involves more than 

simply connecting batteries to achieve the higher voltage; it also requires redesigning all 

high-voltage components within the vehicle to accommodate the increased voltage 

(Engineering, 2023). 

 

The main parameter for charging speed is charger output power, which depends on 

voltage and current. Increasing the charging current would lead to more heat and energy 

loss, so increasing the voltage is a better way to increase power and get faster charging. 

With double the voltage and equal current, a BEV charger could deliver almost twice the 

energy to BEVs. Of course, the chargers and BEV’s converters must be redesigned to be 

able to carry significantly higher power. 

 

The 800-volt architecture also reduces energy consumption. If a battery outputs the 

same power as its voltage increases, that means its current must decrease. Since heating 

and power losses are proportional to the square of the current, heat loss goes down as 



34 

voltage goes up. Lower current also has a positive effect on battery aging, thereby 

extending the battery life. 

 

There are three promising approaches regarding the developing of 800V architectures: 

(1) make the entire BEV’s high-voltage system operate on 800 volts, eliminating the 

need for voltage conversion between components. This approach enables faster 

charging and better efficiency. However, it requires more BEV redesign and 

higher costs. 

(2) have only some essential devices (like the battery pack and drive motor) on 800 

volts, with the rest of the system remaining at 400 volts. The need for voltage 

conversion between 800- and 400-volt devices increases the cost and design 

complexity and adds conversion power losses. However, this solution requires 

less BEV redesign and lower costs for the 400 V system, while still enabling faster 

charging. 

(3) a hybrid solution that involves a battery system capable of switching between 

800 volts when charging and 400 volts when discharging. Other high-voltage 

devices remain at 400 volts. This simple and low-cost solution enables faster 

charging, though discharging at 400 volts means that a reduction in energy 

consumption will not be achieved. 

 

In addition, most BEVs have no transmission box but use a fixed gear box due to overall 

weight and cost consideration. Although the electric motor delivers enough power at 

initial speed phase but will limit the power output at vehicle high speed phase. The 

maximum speed achievable by a BEV is influenced by the power and torque output of 

its electric motor. Electric motors deliver instant torque, providing strong acceleration 

from a standstill. However, as vehicle speed increases, the available torque typically 

decreases. Thus, the motor's power rating directly impacts the vehicle's top speed 

potential.  

 



35 

2.6.1 Lighter Weight of Higher Voltage Batteries  

A typical structure of a high-voltage battery breaks down as shown below Figure 20.  

 

 

Figure 20. HV battery structure (www.evehicletechnology.com, 2021). 

 

High-voltage battery pack structure mainly include 7 parts: 

(1) The battery pack box and cover: it protects all the parts inside, especially the 

battery, and protects the battery from being crushed. 

(2) High voltage wiring harness/busbar: It is to connect the battery module. 

(3) Low voltage wiring harness: It is used to collect the cell signal of the battery 

module, monitor the status of the cell, and then transmit the data to the BMS. 

(4) BDU (battery disconnect unit): High voltage power-off system, control the current 

flow direction, give to different loads, energy distribution unit. 

(5) BMS (battery management system): The brain of the battery pack, which consists 

of the CMU (cell monitoring unit) and the BMU (battery management unit).  



36 

(6) Battery module: the most important thing in the entire battery pack, the source 

of all energy for electric vehicles. 

(7) Cooling water plate: part of the thermal management system of the battery pack, 

which is responsible for the cooling of the battery during heat generation.  

 

The rated voltage of the battery pack is closely related to the multiple high-voltage 

components of the vehicle, including compressors, drive motors, electronic control 

modules, PTC, DC-DC, OBC, high-voltage distribution boxes and other components are 

running under this voltage. 

 

As researched in the report (Lamm, 2019), 800V battery will extremely lighter than 400V 

ones, because Higher voltage allows for reduced current, which in turn necessitates 

thinner, lighter wires and conductors. This reduction in current not only lessens the 

weight of the wiring but also enables a more compact and efficient battery design. 

Additionally, high-voltage systems are often more efficient in power conversion, which 

reduces heat and minimizes the need for bulky cooling components. The advanced 

thermal management systems used in high-voltage batteries are optimized for their 

specific requirements, contributing to a lighter overall design. Thus, the combination of 

lower current demands, efficient power conversion, and optimized thermal 

management results in a lighter and more compact battery system. 

 

2.6.2 High Power of High Voltage Motors 

Automotive motors are mainly developed in the following aspects: high power density, 

diversified development of motor cooling methods, low cost, high integration, good 

vibration and noise characteristics and high efficiency. 

 

To achieve higher torque density, the motor winding of new energy vehicles has 

gradually developed from the traditional circular scattered wire winding to the flat 

copper wire winding. High-speed is the trend of electric vehicle motor development, and 



37 

flat wire winding has gradually become the first choice of major electric vehicle 

manufacturers. 

 

DC motors have been eliminated by the market, switched reluctance motors are still not 

widely used, and permanent magnet synchronous motors and AC asynchronous motors 

are widely recognized by the market. As a drive motor, permanent magnet synchronous 

motor is currently the mainstream choice in the market, and its market share is expected 

to continue to increase in the future. The speed of the switched reluctance motor can 

reach more than 15000r/min, and the reliability, torque performance, and power density 

are also high, but it cannot be widely used at present due to noise, vibration, and other 

problems.  

 

Permanent Magnet Synchronous Motors are generally preferred over Switched 

Reluctance Motors and Induction Motors for developing high-power motors for BEVs 

due to their superior efficiency and performance characteristics. PMSMs utilize 

permanent magnets embedded in the rotor to create a consistent magnetic field that 

interacts with the stator’s electromagnetic field, resulting in high torque density and 

efficient energy conversion. This efficiency translates to better power-to-weight ratios, 

which is crucial for high-power applications in BEVs. Additionally, PMSMs offer excellent 

torque characteristics at low speeds and maintain high performance across a broad 

range of operating conditions, making them ideal for the dynamic demands of electric 

vehicle driving. 

 

In contrast, Switched Reluctance Motors, while robust and cost-effective, suffer from 

high torque ripple and acoustic noise, which can affect the smoothness and comfort of 

the vehicle. SRMs also require complex control systems to manage their operation 

effectively, adding to the system's complexity and cost. Induction Motors, though 

durable and reliable, typically exhibit lower efficiency compared to PMSMs due to 

additional losses in the rotor and the need for more maintenance. They also have lower 

power density and require external components such as slip rings or brushes for rotor 



38 

current management. Thus, PMSMs are generally preferred in high-power BEV 

applications due to their high efficiency, superior torque characteristics, and reduced 

maintenance requirements, providing a more refined and powerful driving experience. 

 

From the perspective of product characteristics, permanent magnet synchronous motor 

and AC asynchronous motor have excellent comprehensive performance, which is the 

favorite choice for new energy vehicles at present as shown in Figure 21. 

 

 

Figure 21. PMSM motor used on Major Electric Vehicles (MarkLines, n.d.). 

  



39 

3 Challenges on High-Voltage System Implementation 

There are some challenges associated with 800V systems, which are mainly related to 

the endurance of key components such as motors, controllers, and batteries. It requires 

a change in every connected component, from the battery pack, BMS, connectors, fuses 

and contactors to drive the inverter power semiconductors, Si IGBTs or SiC MOSFETs 

(Aghabali, et al., 2020) (Conlon, et al., 2022) (Prasad, Namuduri, & Gopalakrishnan, 

2023). 

 

3.1 Protection for Motor Bearing and Electronic Components.  

In terms of motors, changing to high voltage, the requirements for bearing corrosion 

prevention and insulation have increased.  

During the high-frequency power switching process, the motor controller will generate 

induced voltages at both ends of the motor shaft. Under normal circumstances, there is 

a lubricating oil film between the shaft and the bearing, and this oil film has the effect 

of insulation. For lower shaft voltages, the lubricant film still has its insulating properties 

to protect it. When the shaft voltage increases to a certain value and the lubricating oil 

film in the bearing has not yet been stably formed, the shaft voltage will break through 

the oil film and discharge. The shaft current is discharged by the shaft through the 

bearing, and due to the small contact area, high temperature is generated in an instant, 

which causes the bearing to be partially melted (Zhang, Du, Habetler, & Lu, 2009). 

For the 800V system, because its voltage is higher, the voltage change frequency is also 

higher, the shaft current is larger and the frequency is higher, therefore the bearing anti-

corrosion requirements are more important to avoid risk of damage. 

At the same time, due to the increase in voltage/switching frequency, the 

insulation/EMC protection level requirements inside the 800V motor also need to be 

improved, and for electronic devices, continuous and safe operation at such a high 

voltage requires better materials and precision processes. 

 



40 

Some possible solutions include using insulated bearings, which are not easily corroded, 

but the shaft current shaft voltage is still present and may cause damage to other 

components. Another way is to design a conductive discharge circuit, through the design 

of a special ultra-high conductivity and wear-resistant conductive fiber ring, one end is 

connected to the motor housing, and the other end is connected to the motor shaft, 

forming a low-resistance grounding bypass and discharging current to protect the 

bearing from electrical corrosion. These design conditions also have strict requirements, 

such as operating temperature (-50°C~200), maintenance-free, long service life, 

chemical stability, smoke corrosion resistance, etc. 

 

3.2 Maturity of SiC Semiconductors  

800V system has higher requirements for semiconductors, and the current mainstream 

solution is to use SiC materials, which have excellent performance in withstand voltage, 

switching frequency, and loss. They are predicted to replace Si-based power 

semiconductors in future (Sburlan, Vasile, & Tudor, 2021). Taking Si-IGBT as an example, 

the withstand voltage of Si-IGBT is 650V at 450V, if the electrical architecture of the 

vehicle is upgraded to 800V, considering factors such as switching voltage switching 

overload, the corresponding power semiconductor withstand voltage withstand voltage 

level needs to reach 1200V, and the switching/conduction loss of Si-IGBT increases 

sharply at high voltage, facing the problem of rising cost and decreasing energy efficiency. 

However, the detailed performance and environmental resistance of SiC materials need 

to be further verified. Since SiC is still not comparable to IGBT in terms of capacity and 

cost, it will take some time for SiC to become fully industrialized. 

 

3.3 High Requirement to Battery Design and Controlling 

For 800V rated batteries, in practical applications, due to the consideration of allowing 

the battery voltage to increase during regenerative braking or normal charging, 

switching devices with a rated voltage are usually required to be used with more higher 



41 

voltage automotive-grade MOSFETs, which are rarely used in the previous 400V platform 

(Conlon, et al., 2022). 

Because the excessive charging voltage or current may cause the stability of the lithium 

battery electrode material and the electrolyte to be reduced, causing the increase of the 

internal resistance of the lithium-ion battery, the capacity attenuation and even the 

potential safety hazards such as fire and explosion. Under the 800V fast charging 

platform, the charging rate can reach above 4C (Monika, 2023), which puts forward 

higher requirements for the internal resistance and heat dissipation of the battery cell 

(the rapid movement of electric ions will naturally produce a lot of heat), and the module 

level reconsiders the creepage distance, insulation performance, and thermal cooling 

reliability design (Kucevic, Truong, Jossen, & Hesse, 2018). The voltage levels of the 

components also need to be increased to more than 800V, while at the same time having 

to withstand the challenges of high current surges and fast power release. For highly 

integrated battery distribution units (BDUs), the overall consideration of the liquid 

cooling solution and the external high-voltage interface is also difficult. Breakthroughs 

are still needed in battery materials and battery management system (BMS) with high 

control accuracy. 

There are researches to reduce the possibility of lithium precipitation of lithium battery 

anode due to high pressure, including modifications on oxidation, coating, and etch 

(Wang, 2022). Such as use non-carbon-based anode materials (Schneider, 2019). Silicon-

based materials have a higher potential for lithium intercalation and are less risky for 

lithium separation, so they can tolerate a higher charging current than carbon batteries. 

 

3.4 Infrastructure Development and Upgradation  

Another challenge is the infrastructure, for the 800V charging solutions design, the 

charging station also needs to achieve the same charging power, which puts forward the 

need for transformation of the existing charging facilities. Besides, if multiple vehicles 

use 800V high-power charging power at the same time, its impact on the power grid will 

be critical, which corresponding energy storage facilities need to be established to 

reduce the impact. 



42 

4 Simulink of BEV and Battery Charging  

Electric Vehicles are complex systems in which each component has impacts on overall 

performance and EMC influence on each other especially of high voltage and current 

applications. The high-voltage platform technology on electric vehicles can improve the 

efficiency of the vehicle's drive components and increase the driving range of the vehicle, 

which can enhance the advantages of electric vehicles in the competition with fuel 

vehicles. In this chapter, a simulation model of an electric vehicle based on PMSM is built 

in MATLAB/Simulink, which is mainly composed of four subsystems: a lithium battery 

with supercapacitor, a permanent magnet synchronous motor, a control system, and a 

drive cycle with driver. The lithium battery system is used as the energy source while the 

supercapacitor could contribute to the current stabilizing during battery charging and 

discharging. As the drive device, the permanent magnet synchronous motor is discussed 

together with the inverter in the PMSM, and the mathematical model is analyzed more 

intuitively by establishing a mathematical model, and the coordinate transformation is 

introduced to simplify the mathematical model, to understand the relationship and law 

between the parameters of the motor at a deeper level. The electric vehicle acts as a 

load, and the driver gives acceleration and deceleration commands based on the driving 

cycle. The following is a detailed analysis of the working principle and simulation model 

of each device. The structure of the BEV model is created based on some researches 

(Abulifa, Ahmad, Soh, Radzi, & Hassan, 2017), (Lulhe & Date, 2015), (Carter, et al., 2023) . 

The results obtained with simulation might not consider all the influencing aspects, but 

it will give an overview of how the system performs under general conditions.  

 

The overview of the BEV Simulink is built as below Figure 22, including drive cycle, driver, 

controlling unit, inverter, battery, motor, reducer, and vehicle body.  With scopes to plot 

the vehicle speed, battery SoC, torque and battery current and output power.  

 



43 

 

 

Figure 22. Overview of the BEV model main sub-system. 

 

This chapter firstly develops the simulation in MATLAB Simulink of a typical PMSM 

equipped electric vehicle, and battery charging circuit.  Then run the simulation with 

400V and 800V voltages to generate the results.  

 

4.1 Battery  

Lithium-ion batteries are used in this model, a standard model from Simulink has been 

selected, which represents “a generic dynamic model that represents most popular types 

of rechargeable batteries”. Equivalent nominal voltages and rated capacities are set so 

that the battery energy capacities are in same level at the beginning of test. The battery 

energy capacity can be calculated under below equation:  

 

𝐵𝑎𝑡𝑡𝑒𝑟𝑦 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 = 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 × 𝑐𝑢𝑟𝑟𝑒𝑛𝑡 × 𝑡𝑖𝑚𝑒   (2) 

 

With high and low voltages and rated capacity to facilitate a 40KWH battery, comparison 

of the results can be treated in same condition, the SoC of the batteries are set with 80% 

initially, as shown in below Table 3. 



44 

 

Table 3. Battery parameters setting. 

Nominal Voltage  nominal capacity Energy capacity  Initial SoC 

400V 100Ah 40KWH 80% 

800V 50Ah 40KWH 80% 

 

4.2 PMSM Motor, Inverter and control.  

4.2.1 PMSM Motor and Reducer  

PSMSM is selected as the drive motor for this simulation for its high efficiency and 

popularity on the market. The dynamic modeling of a permanent magnet synchronous 

motor is a high-order differential equation, which is extremely complex to compute, 

making the following assumptions to obtain its second-order differential equation. 

(1) The stator winding current is a three-phase symmetrical sine wave. 

(2) Neglecting its high harmonics, core saturation, eddy current and hysteresis losses 

and temperature effects on motor parameters. 

(3) The rotor has no damping windings. 

(4) The induced electromotive force in the phase winding is sinusoidal. 

The PMSM mathematical model after the Clarke transformation and the Park 

transformation is as follows.  The voltage equation is: 

 

𝑈𝑑 = 𝑅𝑠𝑖𝑑 +
𝑑

𝑑𝑡
𝜑𝑑 − 𝜔𝑒𝜑𝑞    (3) 

 

𝑈𝑞 = 𝑅𝑠𝑖𝑞 +
𝑑

𝑑𝑡
𝜑𝑞 − 𝜔𝑒𝜑𝑑    (4) 

 

where 𝑈𝑑 , 𝑈𝑞 , 𝑖𝑑 , 𝑖𝑞, 𝜑𝑑 , 𝜑𝑞 are the d-q axis components of the stator voltage, current, 

and magnetic chain, respectively. 𝑅𝑠  is the stator resistance, 𝜔𝑒  is the rotor angular 

velocity.  

The equations of the magnetic chain are: 

 



45 

𝜑𝑑 = 𝐿𝑑𝑖𝑑 + 𝜑𝑓       (5) 

 

𝜑𝑞 = 𝐿𝑞𝑖𝑞       (6) 

 

Where𝐿𝑑 , 𝐿𝑞  are the inductance of the stator winding d-q axis and 𝜑𝑓  is the rotor 

permanent magnet chain. 

 

The electromagnetic torque equation is:  

 

𝑇𝑒 =
3

2
𝑃[𝜑𝑓𝑖𝑞 + (𝐿𝑑 − 𝐿𝑞)𝑖𝑑𝑖𝑞]    (7) 

 

where 𝑇𝑒 is the electromagnetic torque of the motor and 𝑃 is the pole pair number of 

the motor. In typical conditions, 𝑖𝑑 is set as 0, which then the torque is decided by the 

rotor permanent magnet chain, q axis current and the pole pair numbers.  

 

The mechanical equations of motion are: 

 

𝐽

𝑃

𝑑𝜔𝑒

𝑑𝑡
= 𝑇𝑒 − 𝑇𝐿       (8) 

 

𝑇𝑒 = 𝑇𝐿 + 𝐵𝜔𝑟 + 𝐽𝑃𝜔𝑟     (9) 

 

Where 𝑇𝐿 is the load torque and 𝐽 is the moment of inertia, 𝐵 is the damping coefficient 

and 𝜔𝑟 is the rotor speed.  

 

In this paper, for the convenience of control analysis, the permanent magnet 

synchronous motor model in the Simulink library of MATLAB is selected as shown in 

Figure 23. The model is based on the mathematical model in the (d-q) coordinate system. 

Input the three-phase voltage and load torque from the inverter, and then the stator 

current, d-q axis current, electromagnetic torque, speed and so on can be output from 



46 

the m-port, in this case the mechanical input chooses the rotational port for connection 

to vehicle body rear tires through reducer.  

 

 

Figure 23. Model of Permanent magnet synchronous motor from Simulink. 

 

The power of the motor is determined by the speed and torque according to formula 

below, in which P is power of motor, T is the torque, n is the rotation speed: 

 

𝑃 =
𝑇×𝑛

9040
      (10) 

 

For the same motor, the higher the speed, the lower the torque, and the lower the speed, 

the higher the torque. When the operating voltage of the motor is increased, the output 

speed and torque can be maintained by reducing the speed of the motor and increasing 

the reduction ratio of the reducer to maintain the power of the motor unchanged.  In 

this simulation, the reducer ratio is set with 1.4 in 400V system, and 3 in 800V system to 

keep efficient drag power for the vehicle.  

 

4.2.2 Controlling of PMSM  

The commonly used control methods of permanent magnet synchronous motors are 

mainly direct torque control and vector control. As the main control strategy of Vetor 

control, the FOC control method is widely used in the current control, which realizes the 

control of motor torque (current), speed and position through the control of motor 

current. FOC has double-loop control (current loop and speed loop) and triple-loop 



47 

control (current loop, speed loop and position loop), the inner loop is current loop, the 

outer loop is speed loop and position loop. Double-loop control can realize the precise 

control of motor speed by controlling the size of current, the block diagram of the whole 

dual-loop control is shown in the following Figure 24. For an electric vehicle that 

operates, the speed is controlled by the driver, so there is no speed loop, only a current 

loop. The driver decides to accelerate and decelerate according to the current speed and 

the required speed, and sends the corresponding torque command value to the motor 

control system, and the motor drive system calculates the required Id and iq current 

according to this torque command, and then controls the motor acceleration and 

deceleration (Hailin, Shirong, hongtao, Zhan, & Fuyuan, 2019). In the case of electric 

vehicles, which require high real-time performance, the current is often calculated by 

the command current lookup method. In this case, to simplify the controlling, driver 

acceleration signal been transferred into direct iq_ref to control the motor current for 

speed increase and decrease.  

 

 

Figure 24. FOC Control diagram of PMSM. 

 

The inner loop of the FOC in is divided into several steps including three coordinate 

systems (three-phase stationary coordinate system (A-B-C), two-phase stationary 

coordinate system (α-β), and rotating coordinate system (d-q)), three methods of 

coordinate transformations (Clark transformations, Park transformations, and inverse 



48 

Park transformations), one control algorithm (PID control algorithm) and a method of 

pulse-width modulation (SVPWM).  

 

The process of FOC control is stated as below: 

 

(1) Collect three-phase currents 𝐼𝐴, 𝐼𝐵, 𝐼𝐶; 

(2) Clark transforms the three-phase currents to get the currents Iα, Iβ under the two-

phase stationary coordinate system. 

 

𝐼𝛼 =  𝐼𝑎  −  𝐼𝑏𝑐𝑜𝑠
𝜋

3
−  𝐼𝑐𝑐𝑜𝑠

𝜋

3
    (11) 

 

𝐼𝛽 =  𝐼𝑏𝑐𝑜𝑠
𝜋

6
− 𝐼𝑐 cos

𝜋

6
     (12) 

 

 

 

(3) And then 𝐼𝛼,   𝐼𝛽for Park transformation to get the rotating coordinate system 

under the current, 𝑖𝑑 , 𝑖𝑞; 

 

𝑖𝑑 =  𝐼𝛼 cos(𝜃) +  𝐼𝛽 sin (𝜃)    (13) 

 

𝑖𝑞 =  − 𝐼𝛼 sin(𝜃) + 𝐼𝛽  cos (𝜃)    (14) 

 

(4) Get the rotor speed and angle 𝜃; 

(5) Calculate the error between the actual rotational speed of the rotor, and the set 

target speed. 

(6) Throw the error into the PI controller, the actuator output 𝑖𝑞_𝑟𝑒𝑓;  

(7) Calculate 𝑖𝑑 , 𝑖𝑞 and the set value of 𝑖𝑑_𝑟𝑒𝑓, 𝑖𝑞_𝑟𝑒𝑓 error. 

(8) Throw the error into the PI controller and the actuator outputs 𝑈𝑑  and 𝑈𝑞   

respectively. 

 



49 

𝑉𝑑 =  𝑉𝛼 cos(𝜃) + 𝑉𝛽 sin (𝜃)    (15) 

 

𝑉𝑞 =  −𝑉𝛼 sin(𝜃) +  𝑉𝛽 cos (𝜃)    (16) 

 

(9) 𝑈𝑑, 𝑈𝑞 undergoes inverse Park transformation to obtain 𝑈𝛼, 𝑈𝛽 ; 

 

𝑉𝛼 =  𝑉𝑑 cos(𝜃) −  𝑉𝑞 sin (𝜃)    (17) 

 

𝑉𝛽 =  𝑉𝑑 sin(𝜃) +  𝑉𝑞 cos (𝜃)    (18) 

 

(10) Finally,  𝑈𝛼, 𝑈𝛽 go through SVPWM to calculate the voltage vector action time 

applied by the selected voltage vector to output the signal for inverter 

switching control.  

 

The detail FOC control model is set as below Figure 25 as typical FOC control diagram:  

 

 

Figure 25. FOC control algorithm in Simulink. 

 



50 

As the drive cycle is applied in this model, so the regenerative braking control logic has 

been considered, which include the switch to control the drive or brake mode of the 

vehicle and use PWM generator simulate pulses for the inverter control during 

regenerative braking.  The detail regenerative braking control logic is set as below 

Figure 26, during braking, iq_ref switch to negative value for motor current direction 

reverse and charging energy back to battery. The pulses are generated through FOC 

control algorithm during acceleration, while pulses are generated through the braking 

signals via PWM generator.  

 

 

Figure 26. regenerative braking control logic in Simulink. 

 

4.2.3 Inverter 

The pulse signal generated after the FOC controlling, then to control the switching state 

of the inverter, this step replaces the switching table in the traditional direct torque. 

Then the inverter outputs three-phase voltage and current for the normal operation of 

the permanent magnet synchronous motor, currently, the three-phase current is 

collected, which is used for the calculation of the torque and the magnetic chain and is 

fed back to the given, to complete the whole permanent magnet synchronous motor 

double closed-loop control system. The inverter uses the standard universal bridge 

module in the Simulink, which converts DC into AC during motor driving mode, and 

converts DC into AC during motor generator mode. Typical IGBT/Diodes mode is selected, 

as mostly used on the market, as Figure 27 shows.  



51 

 

 

Figure 27. Inverter module from Simulink. 

 

4.3 Vehicle body 

To calculate the total power requirements is to determine the forces acting on the 

vehicles, in this study a BEV of standard rear single motor is used as an assumption.  

 

The total force on the vehicle is the sum of all the forces given above and as follows： 

 

𝐹𝑡𝑜𝑡𝑎𝑙 = 𝐹𝑟𝑜𝑙𝑙𝑙𝑖𝑛𝑔 + 𝐹𝑎𝑒𝑟𝑜𝑑𝑦𝑛𝑎𝑚𝑖𝑐 + 𝐹𝑔𝑟𝑎𝑑𝑖𝑒𝑛𝑡 + 𝐹𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 (19) 

 

While: 

𝐹𝑟𝑜𝑙𝑙𝑖𝑛𝑔 = 𝑚 × 𝑔 × 𝑓       (20) 

 

which m is the mass of vehicle, g is the f is the rolling resistance coefficient. 

𝐹𝑎𝑒𝑟𝑜𝑑𝑦𝑛𝑎𝑚𝑖𝑐 =
𝐶𝐷×𝐴×𝑉2

21.15
       (21) 

 

which V is the vehicle velocity, CD is the coefficient of air resistance, A is the front area 

of the vehicle. 

𝐹𝑔𝑟𝑎𝑑𝑖𝑒𝑛𝑡 = 𝑚 × 𝑔 × 𝑠𝑖𝑛𝛼      (22) 

 

which α is the slope angle.  

 



52 

𝐹𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 =  𝑚 × 𝑎       (23) 

 

which 𝑎 is the acceleration speed of the vehicle.  

 

Modules from Simulink of vehicle body, wheels, are selected for configurating the vehicle 

model (Nayak, Bohre, & Kumar, 2022), as shown below Figure 28.  

 

Figure 28. Simulation of vehicle body in Simulink. 

 

The models configurated for this study do not represent any environmental dynamic 

influence. For this reason, the configuration of each element is chosen as standard ones. 

The vehicle data sheet chosen based on a typical BEV with rear driving single motor, 

which datasheet stated as below Table 4. 1800kg is the average weight of the BEV 

Passenger car on the market with a front area of 2.4 m2. The Passenger vehicles have a 



53 

drag coefficient of between 0.3~ 0.6, in this case 0.4 is chosen as an average value. For 

the Motor in this simulation, Gear ratio of 3 is selected for better performance.  

 

Table 4. BEV vehicle body parameter. 

Parameter Value  

Mass of vehicle  1800 kg 

Wheel radius  0.35 m 

Vehicle front area  2.4 m2 

Rolling resistance coefficient 0.015 

Drag coefficient 0.4 

 

 

4.4 Drive Cycle and Driver 

Drive cycles are speed-time graphs used to calculate vehicle exhaust emissions and fuel 

consumptions. It can be used in this study to simulate the performance of vehicles under 

different driving circumstances. EUDC, WLTP, FTP75 and other specific drive cycles have 

been applied for evaluate BEV’s range performance as it contains strict driving situations 

stimulate different road driving, example of NEDC (New Eupean Driving Cycle) plot as in 

Figure 29.  

 

 

Figure 29. Drive cycle of NEDC.  

 



54 

The features of typical drive cycles are listed in below Table 5, which include duration, 

average speed, total distance (Banuri, Qayyum, Qureshi, & Ahmed, 2020): 

 

Table 5. Features of different driving cycles. 

Features  Japanese 
10 

EUDC NEDC WLTP  
class 1 

FTP75 China 
CLTC 

India 
Drive  
cycle  

High speed 
(specific) 

Time (s) 135 400 1180 1022 1874 1800 108 85 

Average speed  
(km/h) 

17.7 62.59 33.35 27.6 17.77 28.96 21.93 60 

Max. speed  
(Km/h) 

40 120 120 64.4 91.25 114 42 120 
 

Max. 
Acceleration 
speed (m/s2) 

0.79 0.83 1.06 0.76 1.48 1.47 0.61 0.83 

Total distance  
(km) 

0.664 6.95 10.93 8.09 17.77 14.48 3.948 1.434 

 

 

The Longitudinal Driver block (Figure 30) inside Simulink implements a longitudinal 

speed-tracking controller. Based on reference and feedback velocities, the block 

generates normalized acceleration and braking commands that can vary from 0 through 

1. It can be used to model the dynamic response of a driver or to generate the commands 

necessary to track a longitudinal drive cycle. The “Predictive control” type is selected for 

driver steering control behavior during path-following and obstacle avoidance 

maneuvers. Drivers preview (look ahead) to follow a predefined path.  

 

 

Figure 30. Driver model from Simulink. 

 



55 

4.5 Simulation of Battery Charging Circuit 

The main way applied to BEV lithium battery fast charging is the combination of CC 

(constant current) and CV (constant voltage) charging modes, as shown in Figure 31. In 

the initial stage, in order to quickly increase the charging rate, a large constant current is 

set for charging, and the voltage of the battery rises slowly in this process, this stage is 

the constant current phase, when the battery voltage or SoC rises to the set value, it will 

switch to constant voltage mode, at this time, the voltage remains constant, the current 

gradually decreases, and the charging power is gradually reduced. Until it reaches a near-

full state, it is then floated up with a small amount of power to protect the battery. 

 

 

Figure 31. CC and CV charging mode for battery. 

 

The controlling flow is shown below in Figure 32, during the charging start, some battery 

protection measurements are done to maintain the battery in good condition, such as 

temperature, voltage, etc. And then compare the voltage with set value to decide the 

charging mode, monitoring the status during the charging period, and finally stop 



56 

charging when battery voltage, SoC or temperature reach set value (Shen, Vo, & Kapoor, 

2012 ).  

 

 

Figure 32. Battery DC fast charging controlling flow. 

 

Detail simulation is generated as in Figure 33. A model of battery charging has been 

simulated to evaluate the charging speed of high voltage and low voltage DC charging 

station.  The model includes modules of DC voltage source, IGBT generate the voltage 

levels for battery charging, PWM pulse generating, and control system controlling the 

voltage and current of charging, based on the reference introduced in paper (Arancibia 

& Strunz, 2012) and (Yuexian, Tianyu, Yayu, & Xiaoru, 2014).  The model built in Simulink 



57 

is shown below Figure 34.  By setting high charging voltage to evaluate the battery 

charging speed compared to lower voltage levels.  

 

The charging power parameters are set below Table 6. For 400V Li-ion battery, fully 

charged voltage is 465V, therefore the Max. charging voltage source is set as 466V. For 

800V Li-ion battery, fully charged voltage is 931V, therefore the Max. charging voltage 

source is set as 940V and 1000V. Difference Current values are set for 800V charging 

system between 150A to 350A for evaluating the charging power influences. Battery 

volume varies between 400V and 800V, both of their capacities are set with 40Kwh.  

 

 

Figure 33. Charging controlling algorithm. 

 



58 

 

Figure 34. BEV battery DC charging Simulink. 

 

Table 6. Charging parameters for 400V and 800V battery 

Battery voltage  400V 800V 800V 800V 

Charging power(max.) 139.8KW 141KW 300KW 350KW 

Charging voltage (max.) 466V 940V 1000V 1000V 

Current (max.) 300A 150A 300A 350A 

SoC initial  20% 20% 20% 20% 

SoC end 90% 90% 90% 90% 

Battery volume 100Ah 50Ah 50Ah 50Ah 

Battery capacity 40Kwh 40Kwh 40Kwh 40Kwh 

  



59 

5 Simulation Results and Discussion  

This chapter reveals the simulation results built in chapter 4 as introduced.  The data of 

SoC of battery, vehicle speed, torque of motor and DC current are collected to compare 

the performance of the systems. The initial state of charge of the battery are same from 

80%, the final state of charge after each driving cycles are collected in Table 7.  

 

Table 7. SoC changes after different drive cycles (initial state of charge 80%). 

 
India  JAPAN High 

speed 
cycle 

WLTP EUDC NEDC CLTC-P FTP75 

400V SoC(%) 79.42 79.15 77.48 76.92 76.23 71.72 68.04 57.97 

800V SoC(%) 79.68 79.58 78.49 77.58 77.07 74.69 73.03 69.52 

SoC saving 
(800V VS 400V) 

0.26 0.43 1.01 0.66 0.84 2.97 4.99 11.55 

 

The SoC savings on 800V system compare to 400V system are listed and illustrated in 

Figure 35.  

 

 

Figure 35. SoC comparison of 400V and 800V system after drive cycles. 

 

79.42 79.15
77.48 76.92 76.23

71.72

68.04

57.97

79.68 79.58 78.49 77.58 77.07
74.69

73.03

69.52

55

60

65

70

75

80

India JAPAN High speed
cycle

WLTP EUDC NEDC CLTC FTP75

So
C

(%
)

SOC COMPARISON AFTER DIFFERENT DRIVE CYCLES 

400V 800V



60 

According to the results, the 800V system has more SoC saving than 400V system. The 

most significant difference occurred in the FTP75 drive cycle, where the 800V system 

had 69.52% of the final SoC, compared to 57.97 for the 400V system, which was 11.55% 

more than the latter. In drive cycle FTP75, 800V system gains the more SoC saving of 

11.55%, while on Indian drive cycle, there is very small difference of 0.26%.  

 

Table 8 and Figure 36 show the Max. DC current at different systems under different 

drive cycles. On China CLTC there is the biggest DC current on 400V system of 396.2A, 

with 100.4A on 800V system. Similar on FTP75 drive cycle, with 359A VS to 87.73 A. 

There is also a high DC current on High-speed drive cycle of 348.7 A on 400V system, 

compare to 126.4 A on 800V system.  

 

Table 8. Max. DC current at different drive cycles. 

Max. Current in the drive cycle (achieve the required speed) 
 

India  JAPAN High 
speed 
cycle 

WLTP EUDC NEDC CLTC FTP75 

400V (A) 63.3 129.1 348.7 78.48 156.3 155.9 396.2 359 

800V (A) 17.31 36.81 126.4 19.03 62.69 63.43 100.4 87.73 

 

 



61 

 

Figure 36. Max. DC current on 400V system VS 800V system. 

 

As shown in Figure 37 the distance driven is also linearly related to the saving SoC in 

the 400V and 800V systems, such as the FTP75 drive cycle, which has the longest 

driving range, with the biggest SoC difference. But the shortest mileage is not the 

smallest gap, such as on Indian Dive cycle. 

 

 

Figure 37. SoC saving difference VS Driving distance (Km). 

 

0

50

100

150

200

250

300

350

400

450

India JAPAN High
speed
cycle

WLTP EUDC NEDC CLTC FTP75

M
ax

. D
C

 c
u

rr
en

t 
(A

)
Max. DC current at 400V and 800V system

400V 800V

0

2

4

6

8

10

12

14

0
2
4
6
8

10
12
14
16
18
20

India JAPAN High
speed
cycle

WLTP EUDC NEDC CLTC FTP75

So
C

 s
av

in
g 

d
if

fe
re

n
ce

(%
)

SoC saving difference VS driving distance

Distance (Km) SoC saving



62 

Figure 38 shows the SoC difference vs. the maximum acceleration speed for each driving 

cycle, FTP75 driving cycle with the maximum acceleration speed has the largest SoC 

difference. The Indian drive cycle with minimal acceleration speed has the smallest SoC 

gap between 400V and 800V system.  Since the current is especially lower in an 800V 

system during acceleration phase, the resistive losses in the wiring, motor, and other 

components are significantly reduced, while system energy efficiency increases. This 

efficiency leads to less energy being wasted as heat and therefore less drain on the 

battery, contributing to greater SoC savings. Similarity on regenerative braking mode, 

which 800v systems recover more energy back, because the reduced current (due to 

higher voltage) leads to fewer losses during the energy transfer from the motor to the 

battery, with less wasted as heat. 

 

 

Figure 38. SoC saving difference VS acceleration speed. 

 

Figure 39 shows the relationship between the SoC difference and the maximum speed 

of each driving cycle, and there is no obvious linear relationship between the driving 

cycle with the maximum speed and the SoC remaining. For example, the maximum 

speed of the high-speed drive cycle, and the EUDC drive cycle, their SoC remaining are 

not as large as the lower TOP speed WLTP and FTP75 drive cycles. 

 

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0

2

4

6

8

10

12

14

India JAPAN High
speed
cycle

WLTP EUDC NEDC CLTC FTP75

A
cc

el
er

at
io

n
 s

p
ee

d
(m

/s
2

)

So
C

 s
av

in
g 

d
if

fe
re

n
ce

(%
)

SoC saving difference VS Acceleration speed 

SoC saving Acceleration speed



63 

 

 

Figure 39. SoC saving difference VS Top Speed.  

 

5.1 India Drive Cycle 

This Indian drive cycle has a top speed of 42 km/h, which is like a typical slow driving 

scenario. The waveform of the results is shown in Figure 40, both systems reach the 

speed reference well, while 400V system has high torque and higher current results. 

Although the driving cycle time is relatively short, only 108s, the 800V system has 

acquired more energy saving, the final SoC result is about 0.26% less than the 400V 

system.  

 

 

 

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

0

50

100

150

200

250

300

350

400

400V 800V 800V 800V

C
h

ar
gi

n
g 

d
u

ra
ti

o
n

 (
M

in
.)

C
h

ar
gi

n
g 

p
o

w
e

r 
(K

W
)

Charging duration VS charging power

Charging power(max. KW) Duration (min)



64 

 

 

Figure 40. Waveform of 400V and 800V system in India Drive cycle. 

 

5.2 Japanese 10 Mode Drive Cycle 

The Japanese 10 mode drive cycle was used for emission certification of light duty 

vehicles in Japan. It simulates urban driving conditions. It covers 0.664 km at an average 

speed of 17.7 km/h and lasts 135 s. The maximum speed is 40 km/h.  

 

The waveform of the results is shown in Figure 41, both systems reach the speed 

reference well, while 400V system has high torque and higher current results. After the 

drive cycle, the 400V system ends with SoC 79.15%, while 800V system ends with 79.58%.  

 

 

 



65 

 

Figure 41. Waveform of 400V and 800V system in Japanese 10 mode drive cycle. 

 

5.3 Specific High Speed Drive Cycle (120Km/h) 

In this specific Drive cycle, the vehicle is accelerated to 120 km/h and then maintained 

at this steady high speed for a short time before decelerating to 0, duration of the drive 

cycle is 86 seconds. Results are shown in Figures 42.  

 

 

Figure 42. Waveform of 400V and 800V system in specific high speed drive cycle. 

 



66 

 

5.4 WLTP Class 1 Drive Cycle 

WLTP, which stands for "World Light Vehicle Test Procedure", was jointly developed by 

Japan, United States, and the European Union, and its final version was officially codified 

in 2015. Compared to the old NEDC test, the test conditions for WLTC are significantly 

more complex. The average speed is 27.6 km/h, and the total test time was 1800s. Not 

only does it have a longer range, but the test time is also longer, and the acceleration 

and deceleration process during the test is more random. The results are shown in Figure 

43, the 800V system reserves more energy savings of about 0.66% comparing to the 

400V system. 

 

 

Figure 43. Waveform of 400V and 800V system in WLTP class 1 drive cycle. 

 

5.5 EUDC Drive Cycle 

The EUDC (Extra Urban Driving Cycle) segment was added after the fourth ECE (Economic 

Commission for Europe) cycle to account for more aggressive, high speed driving modes. 

The maximum speed of the EUDC cycle is 120 km/h, and the total duration is 400 s. 

Figure 44 illustrates the test results of 400V system and 800V system. After 400s of 



67 

driving cycles, the SoC of the battery is maintained at 77.07% on 800V system. While the 

SoC ends with 76.23% on 400V system.  

 

 

Figure 44. Waveform of 400V and 800V system in EUDC drive cycle. 

 

5.6 NEDC Drive Cycle 

The NEDC (New European Driving Cycle) is the European standard for endurance test 

conditions, which contains 4 urban cycles and 1 suburban cycle. NEDC working 

conditions are divided into two parts: urban working conditions and suburban working 

conditions. The urban operating conditions consisted of four ECE (Economic Commission 

for Europe) cycle units, with a maximum speed of 50 km/h and an average speed of 19 

km/h during the test, each cycle time of 195 seconds, with a total distance of 4.052 km. 

The suburban test has a total of one EUDC cycle, with an average speed of 62.6km/h, an 

effective driving time of 400s, and a total distance of 6.955km. The NEDC condition is in 

a constant driving condition most of the time, and even in the process of acceleration 

and deceleration, the acceleration is constant, and the "speed-time" curve is very regular, 

which belongs to the category of steady-state conditions. Figure 45 illustrates the test 

results of 400V system and 800V system after the 1180 s driving. 800V system gains 2.97% 

SoC savings than 400V system.  



68 

 

Figure 45. Waveform of 400V and 800V system in NEDC drive cycle. 

 

5.7 China CLTC-P Drive Cycle 

CLTC (China Light - Duty Vehicles Test Cycle) is a light vehicle driving condition standard 

for China's road traffic conditions and driving habits developed by China Automotive 

Research Center which was released in October 2019 and implemented in May 2020. 

The passenger car test condition CLTC-P (China light-duty vehicle test cycle-passenger 

car) includes three speed zones of low-speed, medium-speed and high-speed, with a 

total duration of 1800s, a total mileage of 14.480Km, a maximum speed of 114km/h, and 

an average speed of 28.96km/h. Compared with the WLTP cycle, the average speed of 

CLTC in urban, suburban and high-speed conditions is reduced to varying degrees, and 

the acceleration and deceleration process during the test is softer, but the peak 

deceleration is higher than that of WLTP, and the deceleration time is longer.  Figure 46 

illustrates the test results of 400V system and 800V system. 800V system gains 4.99% 

SoC Saving than 400V system.  

 

 

 



69 

 

Figure 46. Waveform of 400V and 800V system in CLTC-P drive cycle. 

 

5.8 FTP75 Drive Cycle  

FTP75 (Federal Test Procedure) is a standard issued by the United States Energy 

Administration for testing the economy and emissions of passenger cars in urban 

conditions and is used to evaluate the emissions and fuel economy of light vehicles and 

light trucks. The full FTP75 cycle time is 1874s, the theoretical driving distance is 17.77 

km, the average speed is 34.12 km/h, and the top speed is 91.25 km/h. Figure 47 

illustrates the test results of 400V system and 800V system. In this drive cycle, 800V gains 

11.55% SoC savings than 400V system.  

 

 



70 

 

Figure 47. Waveform of 400V and 800V system in FTP75 drive cycle. 

 

5.9 Battery Charging  

In the simulation of charging efficiency, parameter of the charging power is set as in 

Table 9, the SoC changes of the battery were plotted, the system works well when starts 

with CC mode and switches to CV mode when battery voltage reaches pre-set charging 

voltage.  

 

Table 9. Charging data summary of 400V and 800V charging voltage (40Kwh battery). 

 400V 800V 800V 800V 

Charging power(max.) 139.8KW 141KW 300KW 350KW 

Charging voltage (max.) 466V 940V 1000V 1000V 

Current (max.) 300A 150A 300A 350A 

SoC initial  20% 20% 20% 20% 

SoC end 90% 90% 90% 90% 

Battery capacity  40Kwh 40Kwh 40Kwh 40Kwh 

Duration (min.) 15.57 14.83 7.65 7.05 

 

The results are shown in Figure 48 to 52. The 400V charging system charging the battery 

from 20% t0 90% within 15.57 minutes with charging power of 140KW, while the 800V 



71 

charging system charging the 800V System within 7.05 minutes with charging power 

rising to 350KW.   

 

 

Figure 48. Battery charging duration VS charging power. 

 

 

Figure 49. DC charging with 466V,300A for 400V battery. 

 

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

0

50

100

150

200

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300

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400V 800V 800V 800V

C
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Charging duration VS charging power

Charging power(max. KW) Duration (min)



72 

 

Figure 50. DC charging with 940V, 150A for 800V battery. 

 

 

 

Figure 51. DC charging with 1000V, 300A for 800V battery. 

 



73 

 

Figure 52. DC charging with 1000V, 350A for 800V battery. 

 

 
  



74 

 

6 Conclusion and Recommendation 

Electrification is becoming the future trend of the automotive industry, which is not only 

conducive to reducing carbon emissions and impact of global climate change, but more 

importantly, it can improve energy efficiency, save energy, and improve the driving 

experience to attract more consumers to choose electric vehicles, and High voltage 

upgradation is becoming a key technology in this trend.   

 

This paper reviews the characteristics of the main subsystems in electric vehicles, 

including batteries, electric motors, control systems, body and charging systems, and 

reviews different kinds of batteries and motors to select simulation schemes through 

literature review. The challenges to upgrade to 800V system have also been discussed, 

such as technological difficulties of battery, semiconductor, electronic components, and 

pressure on infrastructure.  

 

By focusing on the simulations of BEV system and charging circuit under MATLAB 

Simulink, to understand the BEV and its battery charging philosophy. The performance 

of BEV system and charging system are verified under 400V and 800V levels, including 

the characteristics of energy consumption during different drive cycles, and battery 

charging speed under different charging power. 

 

The results show that the 800V system recorded more SoC savings overall than the 400V 

system over the 8 driving cycles. The largest SoC savings occurred on the FTP75 driving 

cycle, where the 800V system saved up to 11.55% compared to the 400V SoC after a 

17.77km cycle of 1874 seconds, also with significant differences of 14.48% and 10.93% 

on the CLTC and NDEC driving cycles, respectively. Comparing the characteristics of each 

driving cycle, the most relevant is the effect of acceleration speed, the FTP75 driving 

cycle with maximum acceleration speed (1.48m/s2) saves more energy in the 800V 

system, and there is also a certain correlation in the driving distance, while the high 

speed of the cycle is not significantly influencing the results. This is also reflected in the 



75 

DC current in the system, which can be much smaller on 800V system than that in a 400V 

system to achieve the maximum speed in the cycle, without affecting the power output. 

 

For the charging speed, the charging power of 141KW, 300KW and 350KW of 800V 

system is increased by more than 2 times than 139.8KW of 400V system under the typical 

CC-CV charging mode. If to keep maximum charging current the same, the high-voltage 

system can be charged with even more power in less time, which conclude that the 

charging power can be increased by increasing the charging voltage while the cable 

specifications remain the same. 

 

Although the basic goal has been achieved, the controlling models could be further 

optimized to improve realization. And, due to the problem of workload and time, there 

are many details that can be further optimized and improved for the control strategy of 

the system and specific simulations, such as the high-speed motor application, more 

advance PMSM controlling strategy, lookup table method, high-frequency inverter 

application and battery temperature influence. Furthermore, the solution to challenges 

can be more deeply reviewed with the latest development progress. Finally, due to 

professional and tools limitations, many other parameters of electric vehicles are not 

considered in this paper, and there are other topics could be planned for further studies, 

such as the performance and energy loss on new silicon carbide (SiC) switching 

components, comparing the IGBT devices, reducing the impact to the grid by the high 

voltage charging stations with integrating of battery energy storage system, and the 

vehicle electric system isolation technology analysis for endure safety working under the 

high voltages.  

 

 

 

 

  



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7 References 

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Simulation of Battery Electric Vehicle by Using MATLAB-Simulink. 2017 IEEE 15th 

Student Conference on Research and Development (SCOReD), (pp. 383-387). 

Aghabali, I., Bauman, J., Kollmeyer, P., Wang, Y., Bilgin, B., & Emadi, A. (2020). 800V 

Electric Vehicle Powertrains: Review and Analysis of Benefits, Challenges, and 

Future Trends. . IEEE Transactions on Transportation Electrification, (p. 1). 

Aghabali, I., Kollmeyer, P. J., & Bilgin, B. (2021). 800-V Electric Vehicle Powertrains: 

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TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION, VOL. 7,. 

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