Torque Ripple Reduction in BLDC Motor Using Power Converter by Digital Signal Processing Technique

A Brushless Direct Current Motor (BLDC) has a rotor with permanent magnets and has no mechanical commutator which leads to many advantages over brushed DC motors and induction motors. It has been widely used in high performance applications due to its merits. But Torque ripple is one of the major problems in BLDC drives which exists due to several reasons like cogging, waveform imperfections, and supply current ripple resulting from pwm inverters and from phase current commutation. It is desirable to minimize the torque ripple in a brushless dc (BLDC) drive to remove unacceptable speed ripple, vibration and acoustic noise. Minimizing torque ripple is one of the major objectives for the BLDC drives. A wide variety of techniques have been proposed during the past few years for this problem. This paper presents a new circuit topology and a dc link voltage control strategy to keep incoming and outgoing phase currents changing at the same rate during commutation. A dc–dc single-ended primary inductor converter (SEPIC) and a switch selection circuit are employed in front of the inverter. The desired commutation voltage is to be accomplished by the SEPIC converter. The cause of commutation ripple is analyzed, and the way to obtain the desired dc link voltage is introduced in detail. The proposed method is to be analyzed for torque ripple minimization at both high and low speed on different load with various duty cycles using Digital Signal Processor (TMS320LF2407A).