两电平三相四线制的模型（仅作静态仿真演示），脉冲驱动稍微有点不同。三电平三相三线制、三电平三相四线制的都是一样的。-Two-level three-phase four-wire models (for only static simulation demo), pulse drive a little bit different. Three-level three-phase three-wire, three-level three-phase four-wire system is the same.