基于UC3875的移相全桥ZVZCS变换器的设计与仿真

由于基本的移相全桥ZVS变换器存在滞后桥臂实现零电压开通困难、副边占空比丢失、原边环流较大等缺点,而全桥ZCS变换器实现ZCS时需要有较宽的负载调节范围,且对电路的参数要求严格,如果保护措施不当容易产生过压损坏开关管。鉴于上述弊端,本文研究了一种滞后桥臂串联二极管的移相全桥ZVZCS变换器,该变换器采用UC3875为控制芯片,采用平均电流模式的电压电流双闭环控制策略,不仅大幅度降低电路内部的循环能量、减小副边占空比丢失、软开关范围不受电压和负载的影响,而且该系统具有动态响应速度快、系统性能稳定的优点。本文设计了1kW移相全桥ZVZCS DC-DC变换器,通过Saber软件对其进行了仿真分析,仿真结果表明理论分析的正确性。

Design and Simulate of Phase-shift Full-Bridge ZVZCS Converter Based on UC3875

The lagging leg is difficult to realize zero voltage open, the duty cycle lost of the vice edge, the large circulation of the origina! edge and so on. All of above are the weakness of basic Phase-Shift ZVS Full-Bridge Converter. And that, ZCS Full-Bridge Converter realize zero current open need wider adjusting range load, and the requirements of circuit parameters are strict. It is easy to produce over- voltage to damage switch tube if take improper protection measures. In view of above disadvantages, there is a topology and operating principle of Phase-Shift ZVZCS Full-Bridge Converter with two diodes in series with the lagging leg is introduced in this paper. It use UC3875 as control chip, adopt the control strategy of dual closed-loop with a current-loop and a voltage-loop based on the average current mode. In this way, not only can greatly reduce cycle energy of circuit internal, can reduce the duty cycle lost of the vice edge, and its soft switch range from the voltage and load influence, but also the system has a fast dynamic response and stable performance. It design a Phase-Shift Full-Bridge ZVZCS DC-DC Converter which power is lkW, give the simulation analysis to it by the Saber Simulation Software, and the simulation results present the theory analysis is correct.