Active-Clamp Soft-Switching Push-Pull Full-Bridge Bidirectional DC-DC Converter Over a Wide Load Range

In the energy storage scenarios of low-voltage-high-current, the three-switch push-pull full-bridge bidirectional dc-dc converter (TPFBC) can be used with the characteristics of fewer number of power switches and low cost compared with dual-active-bridge. Nevertheless, it has the disadvantages of high voltage stress and difficulty in realizing full-load zero-voltage switching. To address these problems, an improved active clamp push-pull full-bridge bidirectional dc-dc converter is proposed in this article, which is composed by adding a clamping capacitor to the TPFBC. The proposed topology can realize the voltage clamping function, so the low-voltage and low-cost devices are allowed to be used in this circuit. Besides, a minimum inductor current effective value control strategy is proposed in this article to reduce the inductance loss, and the power switches can achieve soft switching in a wide load range. Then, the forward and backward operation characteristics are symmetrical with a smooth switching of charging and discharging modes under the PWM plus phase shift modulation strategy. In addition, the transformer winding voltage has a higher number of levels, and it is closer to the sine wave enabling it to reduce reactive power and improve operation efficiency. The operation principle, detail characteristic analysis, control strategy, power losses analysis, and parametric design are presented, and a 500-W experimental prototype is built to verify the effectiveness.