Torque Ripple Reduction of PM Brushless DC Motors Based on Auto-disturbances-rejection Controller

Abstract

Torque ripple reduction of PM brushless DC motors is considered, and a new approach based on auto- disturbances-rejection controller(ADRC) is proposed subsequ- ently. Inheriting the merit of independent of system model and overcoming the shortcomings of classic PID controller, ADRC possesses good performance with relatively simple algorithm. Starting from the characteristics of the PM brushless DC motors and the principles of the design of ADRC, the motor model is transferred into a series-connection object. Then two one-order ADRCs are constructed to carry out closed-loop control. One ADRC, which represents the outer loop, controls the rotor speed and specifies the reference torque for the inner loop; while the other manipulates the torque to minimize torque ripple, which actually improves the waveform of the feeding current. The inner loop of torque sub-system adopts three uniform extended state observers(ESO) to obtain the estimation torque and the real operational value of the torque sub-system. A one-order ADRC with the DC value as the control input, is then configured. The experiment results show that the scheme ensures prominent reduction of torque ripple when the motor is in operation; moreover, the motor produces good dynamic performance, good robustness and adaptability.