采用三相四桥臂抑制逆变器共模干扰的SPWM控制策略

SPWM Control Strategy to Reduce Inverter Common-Mode Interferences Based on Three-Phase Four-Leg Structure

为了减少三相三桥臂逆变器因电路不对称而产生的共模电压和电流,提出了一种基于三相四桥臂结构的正弦波脉宽调制(SPWM)控制策略。该策略是在SPWM载波移相控制技术基础上,采用跳变后移控制方法,确保任何情况下逆变器四个桥臂的输出都能达到平衡,从而抑制共模干扰的产生。与原来的三相四桥臂SPWM载波移相控制策略相比,该策略突破了SPWM调制指数必须小于0.666的限制,避免了直流电压利用率低下的缺陷,适用于在任意调制指数情况下的工作。仿真和实验证明了该方法的有效性。

In order to reduce the common-mode（CM） voltage and CM current caused by the asymmetry of the circuit in the three-phase three-leg inverter, this paper proposes a novel sinusoidal pulse width modulation （SPWM） control strategy based on three-phase four-leg structure. This strategy, in which the SPWM jump-edge is delayed when zero-state appears, is an improved method on the basis of the SPWM carrier phase-shifting control technology. It can ensure the output balance of four legs in inverter under any conditions, and thus restrains the generation of CM interferences. Compared with the original SPWM carrier phase-shifting control strategy in three-phase four-leg inverter, the jump-edge delay method breaks through the limitation of SPWM modulation index which must be less than 0.666, avoids the extremely low utilization ratio of direct current（DC） voltage, and can be used with arbitrary modulation index. The effectiveness of the control strategy is proved by simulation and experiment results.