一种改进型PWM调制策略逆变器的研究与应用

Study and application of an improved PWM method of converter

针对带独立直流源的级联型多电平逆变器各逆变单元间应力分配不均衡的问题,提出了一种新的调制方法。通过控制各逆变单元开关的导通顺序和导通时间来改善各逆变单元间应力分配不均衡,从而使整个逆变器工作得更稳定。本文所提出的调制策略对于级联型逆变器的控制方法的设计是新的尝试,用9电平的级联型逆变器的拓扑结构作为例子阐述上述控制策略的思想.对于N电平的级联型逆变器,提出了用分组循环思想来解决传统的循环控制策略过于复杂而难于实现的问题,并通过仿真试验来验证所提出的控制策略。

A novel modulation method for cascaded multicell inverter with separated dc sources is presented in this paper to balance the unequal power distribution among different invert cells. Controlling the sequence and working time of the switching status of every invert cell is an easy way to avoid unbalanced power distribution among invert cells, so that the whole system can work more stably in general. This paper provides an idea for the design of switching control method for cascaded inverter in the application field. And 9-level cascaded multicell inverter with separated dc sources is presented for showing this idea. For N-level inverter, an controlling idea of grouping and cycling among every inverting cell is also mentioned. Simulation results are presented in this paper.