Torque ripple reduction of brushless DC motor with harmonic current injection based on integral terminal sliding mode control

Brushless Harmonic current injection to the stator windings is one of the most effective methods for torque ripple reduction of brushless DC motors. Because of multi harmonic contents of the stator currents, the conventional methods based on rotational reference frame cannot be used to calculate the voltage references for voltage source inverter. sliding mode control (SMC), which has high dynamic response to track a time varying command, can be used to force the arbitrary reference current to the stator windings without transfer the motor currents to the rotational reference frame. However, the main disadvantage of SMC is that the system states cannot reach the equilibrium point in infinite time as well as has a major chattering problem. In this paper, a new control method called integral terminal sliding mode control (ITSMC) is used to overcome these drawbacks. In order to show the robustness and performance of the proposed method, this method is compared with a SMC by some simulation and experimental tests. It is concluded that the dynamic response and robustness of the proposed ITSMC method is higher than SMC and ITSMC is an appropriate method to inject the arbitrary reference current to the motor windings.