SVPWM逆变电源电流采样方法的比较

Comparison of Methods for Current Sampling in SVPWM Inverter

电流闭环控制系统中,因电流反馈值的谐波分量而导致转矩脉动,降低了系统的稳定性和控制精度。本文通过仿真和实验比较了采用SVPWM(Space Vector Pulse Width Modulation)逆变电源供电时,系统的3种电流采样方法。结果表明,在PWM波各开关周期的起点或中点时刻,对电机的电流进行采样,能够获得谐波成分相对较少的基波电流值,有利于实现高精度的电流闭环控制。

In closed loop current control systems,such as VC （Vector control） or DTC （Direct Torque Control） drive system,the performance is influenced by the property of the current sampling.Harmonic components in the feedback current which is sampled by current sensor will generate torque ripples in the torque loop and degrade stability and control precision of the system.In this paper,three methods for current sampling of the closed loop current control systems supplied by SVPWM （Space Vector Pulse-width modulation） inverter are compared：current sampling asynchronous with the on-off cycle of PWM （Pulse Width Modulation） wave;current sampling at the start point of each PWM on-off cycle;current sampling at the midpoint of each PWM on-off cycle.Both the results of simulation and experiment indicate that sampling at the start point or midpoint of each on-off cycle can achieve an ideal fundamental current wave with few harmonic components.This method can help to implement a high-precise closed loop current control.Also it can be used in other different systems supplied by PWM inverter with moderate or small capacity,fixed PWM on-off cycle and high carrier wave ratio,such as alternate asynchronous or synchronous drive systems, APF （Active Power Filter） etc.