Motor Control Application of Fixed-Sampling-Interval and Fixed-Depth Moving Average Filters

A moving average (MA) low-pass filter and a counter MA high-pass filter are discussed, and their empirical cutoff frequencies are determined. Compared with the infinite-impulse response filter, the MA-based filters are more suitable in motor control application due to their distinctive frequency response character. However, to benefit from this character, the MA parameters should comply with the motor electrical fundamental period, which will cause discontinuity of the MA on motor electrical frequency variation. This paper proposes a fixed-sampling-interval and fixed-depth MA method to make the MA algorithm fundamentally frequency adaptive. The proposed method combines a running average and an MA, but still has the character of the MA. It is promising in the application of motor control. Based on the proposed method, average speed control, current harmonic reduction control, and real-time electrical parameter calculation are performed on a prototype motor system. Both simulation and experiment validate the effectiveness of the proposed method.