利用矢量合成的三电平变流器SVPWM过调制技术

SVPWM Over-modulation Scheme of NPC Three-level Converter Using Vector Synthesization

三电平变流器工作于过调制区间时,由于中矢量作用时间较长,所以常规的过调制输出矢量顺序会引起较大的中点电压偏移与波动。常用的中点电压平衡控制在过调制区中应用可以抑制中点电压的偏移,但不能减小中点电压的波动。为减小过调制时产生的中点电压波动,提出了一种新的利用矢量合成的过调制输出矢量顺序,该方法可将中矢量的作用时间减小为常规过调制方式的1/3,在实现过调制目标的同时,最大程度地减小了中点电压的波动,改善了系统性能,且双模式与单模式过调制均可采用该法合成大六边形上的输出矢量。仿真结果证明了所提方法的有效性与可行性。

Common neutral-point voltage balance control technique can not decrease fluctuation of the neutral-point voltage but effectively eliminate offset of the neutral-point voltage.In order to decrease fluctuation of the neutral-point voltage,we present a novel output vector order of over-modulation using vectors synthesizing concept.The new method can decrease action time of the middle vector to 1/3 of the conventional over-modulation technology.Therefore,the method can reduce fluctuation of the neutral-point voltage to the full extent,realize the aim of over-modulation,and improve the performance of the system.Both single-mode and dual-mode over-modulation technology can use this method to synthesize output vector on hexagon.The simulation results reveal that the new method is valid and feasible.