Torque Control of Brushless Direct Current Motor Drives Using Single Current Sensor with High Reliability

Due to the simple structure, high torque density, low maintenance, and high efficiency, brushless direct current (BLDC) motors are widely used in automation and industrial applications. A control strategy based on single current sensor is proposed for a four-switch three-phase BLDC motor system to lower cost and improve reliability. The whole working process of the BLDC motor is divided into six modes. Phase c involves four modes, including modes 2, 3, 5, and 6. Only one switch will work in these modes. In modes 1 and 4, two switches will work simultaneously and current flows through phases a and b. Compared to the most recent and highly performed torque control strategy, the proposed offers an improved reliability thanks to the achievement of balanced switching frequencies of the inverter upper and lower switches. Furthermore, the torque ripple is significantly damped during sector-to-sector commutations using a hysteresis current controller. The effectiveness of the proposed system has been validated by simulation results using MATLAB/Simulink software in various operation conditions.