Overvoltage protection system for wireless power transfer systems

A battery charging system for a vehicle comprising:

• a wireless power transfer circuit including an inverter and transmitting inductor and resonant capacitor configured to inductively provide power to a resonant receiving circuit;
• the resonant receiving circuit comprising, an inductor, a resonant capacitor and a first switching device, the inductor having a first end and a second end, the first switching device being connected between the first end and the second end of the inductor, the resonant receiving circuit being connected to a rectifier and a filter capacitor, the first switching device having a first state in which the first end and the second end of the inductor are electrically coupled to each other through the first switching device, and a second state in which the inductor and resonant capacitor are capable of resonating;
• a battery coupled to the resonant receiving circuit for receiving power inductively provided to the resonant receiving circuit;
• and
• a control module configured to control the first switching device to switching between the first state and the second state when the resonant receiving circuit is charging load and a preset condition is satisfied and otherwise, the first switching device is maintained in the first state.