Receiver Current-Stress Mitigation for a Dynamic Wireless Charging System Employing Constant Resistance Control

The voltage stress of compensation capacitors in the wireless charging system could be up to several kilovolts. Things get worse for the dynamic operating condition because the resonant current gets fluctuating with the rigid variations of the coupling condition. In this article, a constant resistance (CR) control scheme on a boost converter is proposed to mitigate receiver current stress, i.e., the peak currents in the resonant tank and the boost chopper inductor. The receiver-side dynamic wireless charging (DWC) system with a postregulated boost converter is introduced by the static operating waveforms. To investigate how speed affects current stress, a receiver-side current analytical model is established based on the closed-loop input admittance of boost and the dc circuit model of resonant tanks. The modeling results illustrate that the overstress problem is prone to occur at high-speed condition under constant current charging control. CR control, which shapes boost input current and voltage in phase, is adopted to address this problem. Comparative studies for full-range speeds and nonideal coupling conditions, conducted by the DWC simulator, show that uniform low-stress performance is obtained under CR control with the same amount of energy transferred. Maximum stress improvement on the receiver resonant current is 29% for ideal condition and 44% for a nonsinusoidal condition when driving at 80 km/h.