Bidirectional Resonant Converter With Minimized Switching Loss Over Wide Operating Voltage Range

In this article, we propose a bidirectional resonant converter having minimized switching loss in a wide operating voltage range. This converter serves as a pulsewidth-modulation (PWM) full-bridge resonant-boost converter in the forward operation and a PWM half-bridge resonant-buck converter in the reverse operation. It can then achieve a wide voltage gain range even in the reverse operation. By employing a T-type active voltage doubler, we can attain almost zero voltage switching at the turn-off instants, and so switching loss that occurred at all active switches becomes negligible. Moreover, the circuit experiences very little instantaneous reactive current under wide voltage variations. Therefore, the proposed converter can accomplish a wide range of voltage gains in both power flow directions and high efficiency over a wide range of operating voltages. We present circuit operation and steady-state analysis in detail. We built a 3.3-kW/400-V prototype that copes with 250~415-V inputs and tested it to demonstrate the superior quality of its circuit design.