Symmetrical PWM control ZCS half-bridge converter schematic diagram

The symmetrical PWM control ZCS half-bridge converter adds an auxiliary branch composed of an auxiliary switch tube, a resonant capacitor and a resonant inductor in series on the secondary side of the traditional asymmetric half-bridge circuit transformer. The main switch tube not only works in a symmetrical state, but the converter can achieve ZCS of all switches and ZVS of all diodes in the entire load range. Like the symmetrically controlled half-bridge, the auxiliary switch is turned on once every half cycle, using The resonance between the resonant capacitor and the transformer leakage inductance creates conditions for all switching tubes ZCS and all diodes ZVS in the full load range, making it difficult to achieve soft switching under heavy load.