Reduction of torque ripple in an electrolytic capacitor-less BLDC motor drive by simultaneous speed and torque control method

Abstract

Brushless DC motors have been widely used in both industrial and non-industrial applications. Commercialization of these drives by reducing their price and increasing reliability, are among the main goals of manufacturers and researchers. These goals have been partially achieved by reducing the number of switches, current or voltage sensors, and elimination of position sensors. However, according to statistics the electrolytic capacitors are both costly and inherently have the highest potential of drive failure. In this study a new control method is proposed based on simultaneous control of speed and torque in order to eliminate the high capacity electrolytic capacitors, and use switching thin-film capacitor with low capacity in DC link instead. This reduces the torque ripples resulting from voltage fluctuations in the DC-link. The validity of the proposed method was demonstrated via simulation. A laboratory prototype of the drive was also implemented to verify the theoretical and simulation results.

Keywords

• Brushless DC (BLDC) motor
• Electrolytic capacitor
• Thin film capacitor
• Torque ripple
• Cost reduction
• Capacitor-less drive