Direct Torque Control of Brushless DC Motor Drives With Improved Reliability

Currently, road vehicles are more equipped with permanent magnet synchronous motors. Particularly interesting are brushless dc (BLDC) motors, which, due to their inherently sensorless operation, are considered as viable candidates in large-scale production industries such as the automotive one. Within this trend, this paper deals with the synthesis and implementation of a novel direct torque control (DTC) strategy dedicated to the control of BLDC motor drives. Compared with the most recent and highly performed DTC strategy, the proposed one offers improved reliability due to the achievement of balanced switching frequencies of the inverter upper and lower insulated-gate bipolar transistors, on one hand, and the reduction in the average value of the motor common mode voltage, on the other hand. Furthermore, the torque ripple is significantly damped during sector-to-sector commutations using a three-level hysteresis torque controller. An experientially based comparative study of the most recent and highly performed DTC strategy from one side and the introduced one from the other side clearly highlights the potentialities exhibited by the latest one.