Control scheme for efficiency improvement of slim type BLDC Motor

Brushless DC (BLDC) Motor is widely used in home appliance, robot, and vehicle industry due to the merits of high power density, low noise, and simple controllability. A demands for the motor, especially slim-type BLDC motor, is expected to increase continuously since the minimizing trend of the actuators is getting attention from various applications. Because a phase inductance of the slim-type BLDC motor is large, it causes a lagging of current compared with back-electromotive force (EMF) in wide range of speed. As a result, there is a problem that reduces the motor efficiency and increases the phase current. Particularly the problem is more serious in high speed range and heavy load condition. This paper proposed control scheme for high efficiency of slim type BLDC motor which can resolve the problems as mentioned above. To synchronize the phase between the current and back-EMF of BLDC motor, it proposed lead angle control method by using current dynamics characteristic. Also, it represented the accurate calculating method of lead angle by using only the maximum value of phase current and information of DC-link voltage. For the verification of the proposed control scheme, various simulations and experiments are employed. As a result, the efficiency improvement of slim type BLDC motor is confirmed.