Torque Ripple Reduction of BLDC Motor with a Low-Cost Fast-Response Direct DC-Link Current Control

In this article, a new low-cost direct DC-link current control (DDLCC) is proposed for the brushless direct current motors. The newly proposed DDLCC method has a fast dynamic torque response analogous to the direct torque control (DTC) method. Additionally, torque ripple reduction between two consequent commutations, the standstill and low-speed operation, the low-cost drive, and the reliability enhancement are provided by the proposed DDLCC method compared with the DTC method. Transferring the motor variables to the stationary or synchronous reference frame, which leads to having a high computational burden, is not required in this method. A simple derivative-based (SDB) method is proposed as well to provide the torque ripple without its dc offset value. The commutation interval is easily detected by a two-level hysteresis controller, and the commutation torque ripple is suppressed by applying the appropriate voltage vectors. Both the DDLCC and SDB methods are analyzed and then compared with some of the available DTC methods. Finally, the validity and performance of all analyzed methods are appraised by simulation and experimental results.