System and method for controlling motor

A system and a method for controlling a motor are disclosed. In the present invention, the period information and the operation cycle are detected by a sensing module for calculating the variations of the rotating speed of the rotor. The duty cycle of the PWM signal corresponding to each timing segment is determined according to the predetermined power. By using the PWM signal to drive the motor, the waveform of the output current is rather smooth and close to a sinusoidal waveform, and noises of the motor are reduced effectively. 种马达控制系统及其方法，其主要由控制模块通过感测模块侦测出马达转子的位置及周期资讯，进步的估算转子转速的变化量，在达成目标输出功率值的要求下，设定在各时序所需的工作周期与占空比(Duty Cycle)，对应输出脉冲调变讯号来驱动马达，令输出的电流波形显得相当平顺与接近正弦波形，有效的达到降低马达运转噪音的功效。