一种基于可变虚拟中矢量的三电平SVPWM调制策略

A Three-level Space Vector PWM Strategy Based on Variable Virtual Middle Vector

T型三电平拓扑因具有高效率、低谐波输出等优点而被广泛应用于电能变换器中,其电容中点电压控制的效果将直接影响变流器性能。文章分析了T型三电平主电路中点电压不平衡问题,提出了一种基于变虚拟空间矢量的调制策略,其利用正、负小矢量和中矢量合成的变虚拟中矢量参与空间矢量调制,有效控制了中点电压的偏移。仿真和实验结果验证了该T型三电平拓扑调制策略在地铁系统中应用的可行性与优越性。

T-type three-level topology has been widely applied in power converters for its high efficiency and low output harmonics, and the performance of this converter is determined by the effect of its capacitor neutral point voltage control. This paper analyzed the neutral point voltage balance in T-type three-level circuit and proposed a variable virtual space vector PWM （VVSVPWM） strategy. By modulating the reference space vector using variable virtual middle vector which is constructed by plus or minus small vector and middle vector, the neutral point voltage has been effectively controlled. The feasibility and superiority of the T-type three-level topology applied on metro traction converter system has been verified by model simulation and experiments.