空间电压矢量调制变频器的低速性能改进研究

空间失量调制(SVPWM)已被广泛地用于变频器的逆变器开关信号生成。为防止逆变器的桥臂发生“直通”,必须设置“死区”时间,这是影响变频器低速性能的一个主要原因。在分析死区效应对SVPWM输出电压影响的基础上,提出死区电压失量的概念,给出死区电压矢量的求取方法。在一个控制周期中,可以预先求出几个死区电压矢量的合成作用矢量,对参考空间电压矢量进行校正,达到消除死区效应的目的。实验结果表明,该方法是有效的。

A Study of Improving Low-speed Performance of the SVPWM Inverter

The voltage space vector PWM (SVPWM) strategy has widely been used to generate the on and off signals of power switches of inverter. The "dead-time" must be set to prevent the two power switches in the same leg of the inverter shorting directly. By analyzing the basic influence of the "dead-time effect" acting on the output voltage of SVPWM inverter, the concept of the dead-time voltage vector is put forward in this paper. The method of evaluating the dead-time voltage vector is deduced. By using it, the reference voltage space vector of the SVPWM strategy can be modified for the aim of eliminating the dead-time effect. This method is simple and doesn't need any additional hardware, which can be realized by modifying the control software. The experimental result has proved that it is effective.