基于空间电压矢量120°解耦的开绕组异步电机双三电平逆变器零序电压消除

由于开绕组异步电机双三电平逆变器系统存在很大的零序电压,导致整个系统在单一直流电压源供电模式时,容易形成零序环流损坏半导体开关器件和开绕组电机绝缘,只能动态地消除系统零序电压的平均值,不能抑制其瞬时值,即在一个开关周期内只能通过改变小矢量的作用时间,使其每个逆变器的零序电压平均值为零。提出一种新的消除开绕组异步电机双三电平逆变器系统零序电压的方法。该方法无需对每个开关周期内系统的零序电压进行动态抑制,直接利用统一快速算法以及空间电压矢量解耦的原理和方法将给定参考电压矢量分解为两个大小相等、方向互为120°的等效参考电压矢量,并由两个逆变器分别单独产生,以此实现对双三电平逆变器系统零序电压的瞬时值的消除。仿真和实验验证了该方法的正确性和有效性。

Elimination of Zero-Sequence Voltage in Dual Three-level Inverter Fed Open-End Winding Induction Motor Based on 120° Decoupled Space-Vector PWM Strategy

Because of the drawbacks of the dual three-level inverter-fed open-end winding induction-motor drive,the whole system has the presence of high zero-sequence voltage.This configuration will produce the zero-sequence current with a single DC power supply that can stress the semiconductor switching devices and the motor.It can only achieve a dynamic eliminating average value instead of suppressing the instantaneous value of the zero-sequence voltage in dual inverters.In other words,it can only suppress the zero-sequence voltage by changing the effective time of short vectors and force the zero-sequence voltage in the individual inverters to a value of zero in each switching cycles in the average sense.In this paper,a novel zero-sequence voltage elimination method for the dual three-level inverter-fed open-end winding induction-motor drive has been proposed.It directly makes the reference voltage vector into two equal and mutually 120° equivalent reference vector by using the unified pulse width modulation and space-vector decoupling PWM strategy which produced by two inverters individually.It can achieve the elimination of instantaneous value of zero-sequence voltage in dual three-level inverter.Simulation and experimental results verified the correctness and validity of the proposed method.