A Simple position sensorless control strategy for four-switch three-phase brushless DC motor drives using single current sensor

Cost minimizing of the electrical machine drives is more attractive for low cost applications. The low cost BLDC driver is achieved by the reduction of switch device, cost down of control, and saving of hall and current sensors. In this paper, a simple position sensorless control strategy for four-switch three-phase BLDC motor drives using single current sensor is proposed. 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. The proposed position sensorless scheme is based on the detection of zero crossing points (ZCPs) of three voltage function that are derived from the difference of line voltages measured at the terminals of the motor. Unlike the conventional methods, proposed control strategy has been used only one simple current controller for three phases. The effectiveness of the proposed system has been validated by simulation results.