New Control System for Four-Switch BLDC Motor Based on Single-Current-Sensor

BLDC motors are, normally, supplied by six-switch 3-phase inverter. 4-switch inverter topology may be used to reduce the cost of the motor drive system; in this case the current control circuit has to insure that the drive system can cope the problem of unbalance voltage of the inverter. The operation of the 4-switch inverter is divided into six operating modes; these modes are categorized into two groups. For further cost reduction, the number of current sensors may be reduced. In this paper, a new control system for 4-switch BLDC motor drive is suggested, the control system includes sliding-mode speed controller and hysteresis direct current controller, the control system designed to be operated depending on one current-sensor. The current controller is developed according to the operating modes of the 4-switch inverter where it consists of three sub-controllers. The proposed system is simulated by using Matlab, the results of the proposed control system is obtained at different operating conditions. Even the performance of the single sensor controller is less quality than the ordinary two-sensor controller, it can be concluded that the proposed controller is prosperous and useful in low cost applications, taking into the consideration the advantage of this controller which is the cost reduction.