A NOVEL 180-DEGREE SENSORLESS SYSTEM OF PERMANENT MAGNET BRUSHLESS DC MOTOR
For the conventional 120-degree sensorless drive of a permanent magnet brushless dc (PMBLDC) motor, the winding without phase current in each conduction interval can be considered to be a sensor for back-EMF detection. However, in the case of 180-degree commutation, back-EMF detection is impossible due to all three phases conduct current in each interval and no back-EMF signals are available on stator terminals. This paper proposes a novel 180-degree sensorless system for a PMBLDC motor. The position and speed information are estimated based on the back-EMF signals, which are estimated from the simple sensing of the stator terminal voltage and phase current signals. Furthermore, the proposed 180-degree sensorless system is able to generate up to 33% more torque than the conventional 120-degree system for the same given power supply voltage. The validity of the proposed system is verified through both simulation and implementation.
sensorless drive 180-degree commutation pmbldc motor