A Self-Tuning LCC-LCC System Based on Switch-Controlled Capacitors for Constant-Power Wireless Electric Vehicle Charging

This project presents, a self-tuning LCC/LCC wireless power transfer system based on switch-controlled capacitors is proposed to maintain a high power factor on the primary inverter side and fixed output power on the secondary side against self or mutual inductance variation of the magnetic coupler. The PI control on the primary side and the method of gradient descent on the secondary side are proposed based on the proposed normalized mistuned LCC/LCC circuit model. Only two switch-controlled capacitors on each primary and secondary side are used to implement the control scheme without the Wi-Fi communication or parameter identification. A 3 kW experiment setup was built in the lab and two different magnetic shields, namely ferrite and nano crystalline, were tested on the secondary pad. According to the experiment results, the proposed system is proven to be able to maintain a high power factor (>0.9) and the desired dc output power against 52% mutual inductance variation and 12% self-inductance variation of the secondary pad. The proposed system can be applied as a wireless charger for electric vehicles or a high-power wireless charger test bench. The performance of the system can be evaluated by using MATLAB/Simulink 2018a software.

Key words: Electric vehicle, LCC/LCC compensation, switch-controlled capacitor, wireless power transfer.