STATOR STRUCTURE OF BRUSHLESS DC MOTOR

摘要

PURPOSE: A rotor is provided to reduce the cogging torque with simple structure. CONSTITUTION: A cogging frequency of the cogging torque is generated according to the least common multiple of the number of rotor teeth and poles of the permanent magnet. Then the frequency wave of the cogging torque is formed by overlapping the wave generated by each teeth. The structure installs the teeth(A-L) of the rotor placed with irregular space to compensate the wave of cogging torque. For example, the motor with 36 slots and 48 poles, i.e. the least common multiple is 144, has a cogging period of 2.5 mechanical angle. Then 3 slots generates the wave having a period of 2.5 mechanical angle so 12 teeth sets(A-L) comprising 3 teeth are placed on the circumference of the rotor as shifting each teeth set as much as 2.5/12 mechanical angle.