A Modified S-S Wireless Charging Circuit With Single-stage Voltage Regulation Capability

Aiming at reducing the size and weight of wireless charging circuit, this paper proposes a new magnetically-coupled wireless charging circuit based on S-S resonance compensation which achieves single-stage voltage regulation, without cascading a DC/DC stage. A new fixed-pulse-width frequency modulation and voltage regulation (FFMVR) control strategy is proposed accordingly. The output voltage regulation can be achieved by inserting zero states in which the current resonating is paused, and zero current switching (ZCS) can be realized naturally. The system is kept resonance by frequency modulation through crossing-zero detection of the inverter bridge’s voltage and primary current. The detailed closed-loop control strategy is given, then the voltage stress of devices, regulation range, parameter optimization as well as efficiency of the system are discussed. Experiments are conducted and the feasibility of the proposed FFMVR strategy are verified.