Reduction of Torque Ripple method for Small Inductance Brushless DC Motor

Abstract

In this paper Reduction of Torque Ripples for Small Inductance Brushless DC Motor is presented. In conventional control methods of brushless DC (BLDC) motor drives, back-electromotive force (EMF) is assumed to be in ideal form and the controller injects rectangular phase current commands to produce the desired constant torque. However, real back-EMF waveform might not be exactly trapezoidal because of non-ideality of magnetic material, design considerations and manufacturing limitations. This makes the generated electromagnetic torque contain ripples in its waveform which is not desirable in motor operation performance especially, in sensitive industries. Moreover, commutation states affect the quality of generated torque by producing torque pulsations because of changes of conducting phases.In this paper, an accelerated torque control scheme for small inductance BLDCM with single dc-link current sensor is presented. First, ripple-free electromagnetic torque control is realized in commutation and conduction regions. Second, the disturbance torque is observed and compensated through the improved disturbance torque controller. The performance of the system is evaluated by using MATLAB/SIMULINK software.