Hybrid cascaded multilevel inverters are widely concerned for it minimizes the number of switching devices,large number of levels,good harmonic performance,and so on. However,the power circulation,difficult to design by modeling and other problems caused by its structural characteristics have affected its practical application for a long time. The hybrid seven levels inverter can run without power circulation with the hybrid frequency carrier modulation,but it introduces a lot of low voltage cells in voltage expansion. Therefore,a novel hybrid cascaded multilevel inverter with high voltage and high power,and the corresponding PWM modulation method was proposed. The method was based on hybrid frequency carrier modulation,and it could prevent the inverter from the problem of power circulation under hybrid modulation. This modulation method enabled the power of the high voltage cells to achieve a natural power balance,so that the inverter was simple to be modular. Finally,the proposed method is verified by simulation.%混合级联多电平逆变器具有使用开关器件数量少、电平数量多、谐波性能好等优点,从而受到广泛关注,但其结构上的特点引起的功率环流和不易模块化等问题一直影响实用化.采用混合频率载波调制法的混合7电平逆变器,可以消除功率环流,但是其在进行电压等级扩展时引入了较多低压单元.提出了一种新型结构的高压大功率混合级联多电平逆变器和与之相应的PWM调制方法,该方法基于混合频率载波调制法,可以避免混合调制下的功率环流问题,并且使高压单元的功率实现自然均衡,从而使逆变器模块化变得简单.最后通过仿真对所提出的方法进行了验证.
展开▼
