Zero voltage switching operation of a push-pull resonant converter with slow feedback loop and online communication

This paper proposes a novel zero voltage switching control method for a push-pull primary resonant converter by regulating its primary resonant shorting period. Also, the same inductive power transfer channel is used to establish a low bandwidth communication channel between the primary and secondary circuits based on frequency disturbance and temporary shorting of the power pickup. Practical results show that the system is able to track zero-voltage switching frequency automatically under variations of load, magnetic coupling, and other circuit parameters; and at the same time it can transmit and detect simple low bandwidth ON or OFF signals between the primary and secondary circuits.