单极性移相控制高频脉冲交流环节逆变器研究

RESEARCH ON UNI-POLARITY PHASE SHIFTING CONTROLLED INVERTERS WITH HIGH FREQUENCY PULSE AC LINK

高频脉冲交流环节逆变器电路结构由高频逆变器、高频变压器、周波变换器构成。在不增加电路拓扑复杂性的前提下,如何解决高频脉冲交流环节逆变器固有的电压过冲现象和实现周波变换器的软换流,是这类逆变器的研究重点。单极性移相控制高频脉冲交流环节逆变器能够将输入直流电压先调制成双极性三态的电压波,然后再解调成单极性SPWM波,经输出滤波后得到正弦电压。周波变换器功率开关是在前极输出的双极性三态的电压波为零期 间进行开关转换,从而实现了ZVS换流。该文深入分析研究了高频脉冲交流环节逆变器稳态原理特性与单极性移相控制策略。采用状态空间平均法建立了逆变器平均模型,获得了输出电压、滤波电感电流、共同导通时间、单极性SPWM波占空比等关键电路参数的设计准则和逆变器的外特性曲线。设计并研制了1kVA 270VDC/115V400HzAC原理样机,试验结果证实了理论分析的正确性。这类逆变器具有电路拓扑简洁、两级功率变换(DC/HFAC/LFAC)、双向功率流、周波变换器实现了ZVS换流、单极性SPWM波、输出电压波形质量高、负载能力强等优点,包括全桥全波式、全桥桥式两种电路,前者适用于低压输出逆变场合,后者适用于高压输出逆变场合。

The steady principle of the inverter with a high frequency pulse AC link and the uni-polarity phase shifting control strategy are investigated. The inverter's average model is presented by using the state-space averaging approach. The design criterion of key circuit parameters, such as output voltage, filtering inductance, common conduction time,uni-polarity SPWM waveform's duty cycle etc are obtained. The prototype of an IkVA 270VDC/115V400HzAC inverter is designed and developed.The theoretical analysis is verified by the test results .This kind of inverter has the advantages, such as simple topology, two-stage power conversion (DC/HFAC/ LFAC),bi-directional power flow, soft commutation of cycloconverter ,uni-polarity SPWM waveform,low THD of the output voltage, strong load ability etc. It has two kinds of circiut topologies: a full bridge-full wave cirquit topology is suit able to thecose of low output voltages and a full bridge-full bridge circuit topology is suit able to th case of high output voltages.