Patent ID: 9534612
Date: 2017-01-03
CPC Classifications: F04D,Y02B

Claim:
1. A control method of a fan, comprising steps of: detecting a rotational speed of a blade and a rotor position of the blade; generating a control signal according to the rotational speed and a predetermined rotational speed; obtaining a Back-EMF waveform according to the control signal, the rotational speed, the rotor position and a waveform, wherein the waveform is derived from an induced electromotive force of a coil of a motor of the fan is measured by an oscilloscope and digitalized to be a prototype for the Back-EMF waveform; adjusting the phase of the Back-EMF waveform; and outputting a switch control signal where the switch control signal is used to control a switch for the blade, wherein the motor generates a first sine-like wave signal, which is a Back-EMF of the motor, and the control method further comprises steps of: