基于扩展移相的隔离型AC-DC变换器零矢量PWM调制策略

Zero-vector PWM Modulation Strategy of Isolated AC-DC Converter Based on Extended Phase-shift Method

传统隔离型双向AC-DC变换器多为两级式结构,变换器效率低、控制系统复杂,现有的单级式解决方案通常依赖大量实时计算,难以兼具低电流应力、宽软开关范围和高功率传输能力特性。为此,该文设计基于双有源全桥的新型单级隔离型双向AC-DC谐振变换器,提出一种含有零矢量的复合频率调制策略。从高频开关周期入手,利用数学推导,证明所提方案在实现自动功率因数校正功能的同时,可降低开关器件的开关频率,免除附加吸收电路,实现交直流全桥的软开关,且几乎无功率回流,从而有效提升变换器的功率传输能力,所提单变量调节方法简化控制系统设计。最后,搭建额定功率为450W的仿真和实验平台,证明理论分析的正确性和调制策略的可行性。

Conventional isolated bidirectional AC-DC converters are two-stage structure,which leads to low efficiency,and complicated control.Existing solutions of single-stage converters usually rely on complicated real-time calculations.It is difficult to realize the features of low current stress,wide soft switching range and high power transmission capability.In this paper,a novel single-stage isolated bidirectional AC-DC converter with a resonant tank based on dual active bridge is designed to solve the above problems,and a composite frequency modulation strategy with zero vector is proposed.By using mathematical derivation,it is proved that the proposed modulation reduces the switching frequency of MOSFETs with automatic power factor correction.Meanwhile,additional snubber circuits is not required,and soft switching of AC and DC full bridges are realized.The power transmission capacity is effectively improved as there is almost no power backflow.In addition,the single variable adjustment simplified the control system design.The simulation and experimental platforms with rated power of 450W are built,which proves the effectiveness of the theoretical analysis and the feasibility of the proposed modulation strategy.