中文说明：本模型为单项你变模型，将直流电逆变成方波，分别采用四个脉冲发生器控制四个igbt管，经滤波后得到输出结果。
English Description：
This model is a single variable model. The direct current is inversely converted into square wave. Four IGBT tubes are controlled by four pulse generators respectively, and the output results are obtained after filtering.