Torque Ripple Reduction of BLDC Motor using Modular Multilevel Converter

Brush Less DC (BLDC) motors are popularly used in low and medium power applications such as aerospace, home appliances and robotics. These motors are more compatible with variable speed drive systems. The BLDC motors has many advantages compared to other low and medium power motor like fast dynamic response, high efficiency, high reliability and less maintenance. The ideal BLDC motor has a trapezoidal electromotive force (EMF) and quasi-rectangular current. The trapezoidal EMF can be achieved, but quasi-rectangular current cannot be achieved due to presence of inductance in stator winding. As the stator current is not quasi-rectangular shape torque ripple present in BLDC motors, the torque ripple causes erroneous operation of the motors and need to be limited and reduced. In this paper the modular multilevel converter (MMC) is controlled with phase shift pulse width modulation (PSPWM) technique, the results of the proposed MMC are compared with the conventional cascade H-Bridge (CHB) converter.