Design of Controller for Sensorless BLDC Motor using Back-EMF Technique

Motor is that the heart of the many industrial automation and motion management applications. Brushless DC (BLDC) motor drives are widely employed in several applications, starting from small to high power applications, thanks to their high potency, low maintenance, need tiny area, salient operation and high torque to power ratio, etc. The rotor position should be non inheritable so as to drive a BLDC motor. The position of the rotor is known by hall sensors and encoders, but when these types of sensors are used to drive BLDC motor, the circuits become very complex and large. Therefore accuracy and performance of BLDC motor drivers should be enhanced through sensorless technology. Many sensorless strategies are existing in literature to sense the rotor position of motor, but this paper explains and proposed zero crossing back-EMF detection method. This paper work on analysis of sensorless techniques to sense the rotor position and PWM based speed control of inverter-fed sensorless BLDC motor. Modeling and simulation of three phase star connected sensorless BLDC motor is done MATLAB environment. An accurate speed estimation has been achieved by using back EMF zero crossing speed estimation method. Fast response with negligible subsiding time has been obtained by this technique of sensorless speed estimation of BLDC motor.