The invention discloses a permanent
magnet brushless motor sensorless starting method. The permanent
magnet brushless motor sensorless starting method comprises the steps that firstly, a rotor is positioned at a specific position through a rotor prepositioning device, single-step acceleration is carried out according to the given single-step acceleration current and single-step
acceleration time obtained by calculation, single-step acceleration is directly switched to
closed loop acceleration after being carried out, rotor position signals in a three-phase suspended state are detected every fixed period, the power-on phase sequence is determined according to the rotor position signals, whether counter potential signals are stable or not is judged through a
signal comparison method while
closed loop acceleration is carried out, and when stable counter potential signals can be detected within one
phase conversion period, a normal counter
potential method is switched to for operation, wherein the single-step acceleration and the
signal comparison method can ensure that a motor is started at the highest speed, and the
closed loop acceleration process can ensure that the motor supplies power accurately in the acceleration start process and step-out is avoided. By means of the method, an efficient permanent
magnet brushless motor can be started accurately, rapidly and efficiently, the optimization process is simple, universality is high, the success rate of starting can be improved greatly, no sensitivity to load changes exists, and the start program does not need to be changed when loads and the working
station change within a certain range.