An improved current control method for torque improvement of high-speed BLDC motor

The BLDC (brushless DC) motor is characterized by linear torque to current and speed to voltage. It has low acoustic noise and fast dynamic response. Moreover, it has high power density with high proportion of torque to inertia in spite of small size drive. However, at high-speed operation, torque and speed response characteristic is deteriorated by the motor inductance components in stator windings. It is difficult that the BLDC motor is used to the industrial application requiring a wide range of operating speeds. Phase advance angle control method of different methods used to improve torque and speed response is used widely at high-speed operation. However, conventional phase advance angle control method was considered about forward motoring mode. Therefore, position information error of rotor that reverse motoring mode has phase lag angle of double comparing with forward motoring mode is occurred. Consequently, torque performance is destroyed significantly. In this paper, a control method using adjustment of the phase advance angle is proposed. This proposed method improves the torque and speed response characteristic by minimizing delay of current at high-speed operation. Simulated results prove the effectiveness of the proposed method through comparison with the conventional control method.