Controller and control method for an asymmetric half-bridge power supply

Abstract

A controller and a control method for an asymmetric half-bridge power supply are disclosed. The asymmetric half-bridge power supply includes a first arm switch and a second arm switch forming a half-bridge, and a resonant circuit connected to the half-bridge. The method includes providing a duration parameter reflecting a second turn-on time of the second arm switch in a earlier switching cycle; providing a control signal to turn on the first arm switch for a first turn-on time in a later switching cycle; detecting whether the first arm switch has performed ZVS in response to a signal edge of the control signal to adjust the duration parameter accordingly; determining the second turn-on time of the second arm switch in the later switching cycle based on the duration parameter; and turning on the second arm switch for the second turn-on time after the first turn-on time in the later switching cycle.