Analysis of position and speed control of sensorless BLDC motor using zero crossing back-EMF technique

Motor is the heart of many industrial automation and motion control applications. Brushless DC (BLDC) motor drives are widely used in a many applications, ranging from low to high power applications, because of their high efficiency, low maintenance, require small space, salient operation and high torque to power ratio, etc. The rotor position must be acquired in order 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 methods are existing in literature to sense the rotor position of motor, but this paper explain 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 in MATLAB/Simulink environment. An accurate speed estimation has been achieved by using back EMF zero crossing speed estimation method. Fast response with negligible settling time has been obtained by this method of sensorless speed estimation of BLDC motor.