METHOD OF CONTROLLING BRUSHLESS DC MOTOR

摘要

A method of controlling a brushless DC motor is provided to control the motor according to a zero crossing point in which a counter electromotive force of the motor becomes zero. When a brushless DC motor is driven, a linear function in which a linear non-excitation phase voltage(Va) of the brushless DC motor is varied at a constant ratio is obtained. A zero crossing time(t_zcp) in which the non-excitation voltage of the brushless DC motor becomes equal to a half of DC-link voltage of a power of the brushless DC motor is calculated by using the linear function. The zero crossing point is determined by using the calculated zero crossing time, and the motor is controlled according to the zero crossing point.