Analysis and compensation of current measurement error in vector controlled AC motor drives

In this paper, the effects of current measurement error inherent in all categories of AC motor drives are discussed and a compensation method is proposed. Recently, as the higher performance of torque control is required, current measurement error classified as offset error and scaling error becomes considerable. It is demonstrated that the offset error causes the torque of a motor to oscillate at the stator electrical frequency, f_e, and the scaling error, at the frequency, 2 f_e, respectively. These torque ripples deteriorate the performance of speed control because they act as disturbance loads. The simulation and experimental results shows that the proposed compensation method can improve the performance of torque control by eliminating torque ripples effectively