一种新型正激式三电平逆变器

本文提出以正激变换器为基础的正激式三电平逆变器。该变换器电路结构由依次连接的输入高压直电源、三电平变换器、高频变压器、输出周波变换器、输出滤波器以及输出交流负载构成，具有高频电气隔离、电路拓扑简洁、两级功率变换（DC／HFAC／LFAC）、双向功率流、输出滤波器前端获得三电平低频电压波、负载适应能力强、适用于大功率变换场合等特点，能够将一种不稳定的高压直流电变换成稳定的正弦交流电压。和传统的正激式两电平逆变器进行比较，可以得出该逆变器能减小输出滤波电感、并能降低变换器主功率开关管电压应力的结论。同时，分析了该逆变器的工作原理，设计了控制策略，并通过仿真论证了该逆变器电压应力小、输出电压质量高等特点。

A Novel Forward-mode Three-level Inverter

A circuit topology of the Forward-mode three-level inverter is proposed. The kind of circuit topologies are constituted of input high DC voltage, three-level converter, high frequency transformer, output cycloconverter, output filter and so on. The converter has the advantages such as simple topology, two-stage power conversions（DC/HFAC/LFAC）, bidirectional power flow, high frequency electrical isolation, three-level voltage across the output filter and so on. The circuit structure is used for transferring the unstable DC voltage into a regulated constant frequency sinusoidal voltage. Compared with the traditional forward-mode two-level inverter, it could obtain the conclusion that the inverter can reduce the output inductor, and lower the voltage stress of the power switch. The operation principle and control strategies of the inverter were investigated. By modeling and simulation, the performances of the inverter were verified, such as low switch voltage stress, high quality of output waveform and so on.