Combined BLDCM and Encoderless PMSM control for electric hub motor drives

This paper presents combined BLDC/PMSM control drive, which is assisted by low-cost Hall effect sensors for rotor position estimation. The major aim is to produce smooth torque and current in order to improve the efficiency of the drive without using any encoder. During the Encoderless PMSM control mode, the rotor position estimation is achieved by means of Taylor series expansion based on the Hall effect signals. The three Hall effect sensors are also used to startup the machine with high peak torque, and to reset the error on the rotor position estimation every 60 electrical degrees as well. The control algorithm has been implemented and tested in order to drive a Brushless hub motor to be used for EV propulsion purpose.