高压大功率全桥零电压开关PWM变换器研究

High voltage, high power, full-bridge zero voltage switching PWM converter

高压大功率全桥PWM变换器中整流管寄生电容与变压器漏感相互作用 ,会导致严重电压过冲及振荡现象 ,大大增加整流管电压应力及电流应力 ,必须采取抑制措施 .现有各种吸收电路损耗大、抑制效果不理想 ,影响效率 .采用次级有源箝位方式不仅能有效抑制电压过冲和消除振荡现象 ,而且箝位电路损耗小 ,非常适合于电压高、功率大的DC/DC变换器 .变压器原边串联饱和电感 ,利用其特有临界饱和电流特性 ,能有效扩大变换器零电压开关负载范围 ,轻载效率提高 2 % .给出了变换器拓扑结构、次级箝位电路稳态分析、关键参数设计及实测波形 ,该拓扑已成功应用在 5kW、开关频率 10 0kHz的电源模块中 .

The interaction of rectifier capacitance with the leakage inductance of the transformer in a high-voltage, high-power of full-bridge PWM converter results in severe voltage overshoot and ringing across the rectifiers. The drawbacks of several solutions were high losses and low efficiencies. The paper presents a soft-switching full-bridge PWM converter using saturable inductor and secondary active clamp. The nondissipative snubber completely eliminates the voltage overshoot and ringing across the rectifiers. The saturable inductor provides a wide ZVS load range. The principles of operation and design considerations are presented. The experimental verifications from 5 kW prototype converter operating at 100 kHz are presented.