一种中点电位平衡控制和共模电压抑制策略

针对变频器通过长电缆对电动机供电过程中同时存在共模电压、过电压和中点电位不平衡的问题,分析了共模电压与过电压的产生机理,以及中点电位不平衡对共模电压的影响;提出了一种中点电位平衡控制和共模电压抑制策略,即在传统三电平逆变器基础上增加第四桥臂,通过控制第四桥臂的电流来控制中点电位平衡,通过优化主电路的SVPWM调制策略抑制共模电压。Matlab仿真实验验证了该策略的有效性。

A strategy of neutral-point potential balance control and common-mode voltage suppression

For problems that there are common-mode voltage,over voltage and neutral-point potential imbalance simultaneously in power supply of inverter to motor through long cable,generation mechanisms of common-mode voltage and over voltage were analyzed as well as effect of neutral-point potential imbalance on common-mode voltage.A strategy of neutral-point potential balance control and commonmode voltage suppression was proposed,namely adding the fourth leg to traditional three-level inverter,controlling current of the fourth leg to realize neutral point potential balance and optimizing SVPWM modulation strategy of main circuit to restrain common-mode voltage.Effectiveness of the strategy is verified by Matlab simulation.