A Modulation Optimization Strategy for Phase Shift Full Bridge with Low Freewheeling Loss

The phase-shifted full-bridge converter is widely used in fields such as electric vehicles and renewable energy due to its advantages of high efficiency and wide input voltage range. However, conventional modulation methods may lead to large diode freewheeling loss during the freewheeling period. This paper proposes a new modulation method to reduce freewheeling loss. By increasing the duty cycle of the switching tubes in the rectifier circuit, the freewheeling time through body the diodes can be reduced or eliminated. Finally, a prototype with a switching frequency of 50kHz, 450 V-900V input, and 12-16V@2kW output was designed to verify the proposed modulation strategy, achieving an efficiency improvement of 0.2%.