Approach for torque ripple reduction for brushless DC motor based on three‐level neutral‐point‐clamped inverter with DC–DC converter

Abstract

This study proposes a novel topology for reducing commutation torque ripple in a brushless DC motor (BLDCM) drive system using a three-level neutral-point-clamped (NPC) inverter combined with single-ended primary-inductor converter (SEPIC) converters. In the BLDCM, current ripples arise because of the influence of stator winding inductance, which generates torque ripples. The torque ripple that is generated in the commutation period prevents the use of BLDCM in high-precision servo drive systems. In this study, two-stage converters are proposed to reduce the torque ripple. The first stage consists of two SEPIC converters to obtain the desired commutation voltage according to motor speed. A dc-link voltage selection circuit is combined with the SEPIC converters to apply the optimised voltage during the commutation interval. To reduce the torque ripple further, a three-level NPC inverter is used to apply a half dc-link voltage across the motor winding and this effectively reduces the torque ripple. Experimental results show that the proposed topology is able to reduce commutation torque ripple significantly under both low-speed and high-speed operation.

Analysis and Suppressing Speed Fluctuations in Brushless DC Motors

“…According to the Fig.7c, the (12) When the two expressions written for the torque in Eq (12) are considered together, the magnitude of the relative fluctuation in the commutation intervals can be expressed as in Eq (13). 4 a.) If U dc > 4E m , then t f > t r , and torque will continue to increase during commutation.…”

A New Approach of Minimizing Commutation Torque Ripple for BLDCM

“…The main studies on reducing the commutation torque ripple include overlap commutation, two-phase and three-phase conduction modes combination, adding power supply circuits in front of the three phase inverter, modifying power topology, decoupling control, and the sinusoidal current supply [2][3][4][5][6][7][8][9][10][11]. Overlapping commutation and duty pulse width modulation (PWM) optimization are adopted to reduce the torque ripple in [2].…”

“…A novel inverter topology, which can supply higher dc-link voltage for the freewheeling phase and reduce commutation time, is presented [7]. In [8], the three-level inverter is combined with the single-ended primary-inductor converter (SEPIC) to reduce the current and torque ripples. The electromagnetic torque can be controlled by the q axis component of the current vector [9].…”

Research on Control Method of Brushless DC Motor Based on Continuous Three-Phase Current

“…Regarding torque pulsation of brushless DC motor, non commutation current hysteresis control adopted in literature [2] is able to achieve square wave control at low speed of motor but its effect at high speed of motor is to be improved. It is advisable to add boost and buck circuit to front-stage of inverter to decrease commutation torque pulsation of motor [3] [4]. The control method presented in literature [5] is to add voltage source to neutral point to decrease commutation torque pulsation.…”