Front-End Parameter Identification for Performance Optimization and Load Voltage Regulation of Detuned Wireless Power Transfer Systems

Abstract

The technology of wireless power transfer (WPT) has been in accelerated adoption for charging battery-powered devices, particularly in electric vehicles. The variable coupling coefficient between the transmitter and receiver coils and variable equivalent load resistance are the factors affecting the system’s operation. In addition, it is not feasible in practice to perfectly match the resonance frequencies of transmitter and receiver circuits due to parameter variation, rated component tolerances, and manufacturing mismatches. The authors investigated a new system identification method based on nonlinear fitting in order to improve the issues related to parameter uncertainty. The operation is enhanced by employing a frequency control methodology to regulate the load voltage. The system is optimized for zero voltage switching (ZVS) and low conduction loss by the frequency control algorithm to keep the operation efficient. This article shows a very cost-effective and simple measurement of the transmitter’s current magnitude and detection of parameter changes to achieve the new optimum operating point under the dynamic operating conditions. The effectiveness of the proposed method has been validated in the laboratory with experimental results from a prototype, confirming the theoretical analysis and design.