Feed-forward Compensation of load and parameter variations of electric drive

The paper presents a method to compensate effects caused by slow varying loads and plant parameters drift as well as by detuned controller using a simple yet robust algorithm in voltage controlled electric drives. In case of known variations an analytical expression of pre-computed feed-forward compensation voltage is derived, while in presence of unknown disturbances the control algorithm uses a simple Luenberger observer fed by data from a low cost encoder to estimate the feed-forward voltage command reflecting the deviation of the model from its nominal value. It is shown that the feed-forward command reflects parameter changes as well as load torque and slow varying actuator and measurement noises. Simulation and experimental results are given to describe the control algorithm performance and limitations.