逆变器驱动电机的共模电压和轴电压的抑制

Suppression of common-mode and shaft voltages in inverter-driven induction motor

为了抑制逆变器驱动电机的共模电压和轴电压,改进了特定谐波消除脉宽调制(SHEPWM)方式。利用共模谐波性能因子,求出SHEPWM的开关角度。在40～45Hz采用消除三次谐波的改进SHEPWM方式,消除低次谐波分量;在45～50Hz采用不消除三次谐波的常规SHEPWM方式。这两种方式在45Hz处实现了平滑切换。该SHEPWM方法结合无源共模滤波器方案,在一个三电平中点箝位式逆变器上得到实现,在电机端获得较低的共模电压和轴电压。

A selective harmonics elimination pulse width modulation （SHEPWM） scheme was used to suppress common mode and shaft voltages in a three-level neutral-point-clamped inverter-driven induction motor system. A figure of merit for the harmonics was used to find the correct switching angles for the scheme. An improved SHEPWM which eliminates tripling order harmonics was used at 40-45 Hz, while the conventional SHEPWM was used at 45 - 50 Hz. The switching between the two modes at 45 Hz is very smooth. Together with a well-designed passive common mode filter, the harmonics eliminates scheme significantly reduces both the common mode voltage and the shaft voltage within the frequency range of interest.