DSP based sensorless control of permanent magnet brushless DC motor

A closed loop speed control scheme for a Permanent Magnet Brushless DC (PMBLDC) motor is implemented using single current sensor without position and speed sensors. The rotor position information is derived from the back.,emf of the motor and this in turn is used for determining the rotor speed. The Various aspects of DSP based closed loop speed control (such as derivation of position, current sensing, speed controller and PWM generation) of the PMBLDC drive system are discussed. The DC link Current is sensed for feedback, which reduces the requirement of current sensor and hence limits the overall cost of the drive system.