五电平逆变器窄脉冲补偿方法的研究

以五电平逆变器为例对多电平逆变器窄脉冲补偿方法进行了研究,分析了窄脉冲的各种情形,基于多电平载波PWM方法,提出了一种综合的处理方法--多电平零序电压注入(Multilevel Zero-sequence Vohage Injection,即MZSVI)补偿方法,即注入同符号零序电压、取三相中零序电压的极值以及两倍最小脉宽零序电压注入方法.仿真结果表明,采用MZSVI补偿方法后提高了输出电压,输出电压总谐波含量THD也大大减小.MZSVI方法可以推广到任意电平的逆变器的控制,可以有效地进行控制更高电压的中压大功率变流器,而且这种方法也适用于其它类型的多电平逆变器的窄脉冲补偿.

Study of the Narrow Pulse Compensation Technique of Five-level Inverters

As an example of five-level inverters, compensation technique of multilevel inverters is investigated in the paper based on multilevel carrier-based PWM technique, the various circumstances of the NPW in the five-level inverter is analyzed in details. A comprehensive method, which is called multilevel zero-sequence voltage injection (MZSVI) compensation technique, is proposed to deal with the special problems due to compensating NPW of five-level inverter. That is injecting zero-sequence voltage of the same sign, choosing the extreme value of the three phase zero-sequence voltages or injecting zero-sequence voltage of twofold minimum pulse width. It is shown by simulation results that output voltage can be increased and the THD of output voltages can also be greatly reduced due to the MZSVI compensation technique. The MZSVI technique can be extended to inverters of arbitrary levels, and thus medium voltage inverters with more higher voltage can be effectively controlled, and further more it can also be applied to compensating narrow pulses in other types of multilevel inverters.