| 摘要 |
<p>A method of controlling a brushless motor in which an alternating voltage to is rectified D1-D4 to provide a rectified voltage, and a winding of the motor 7 is excited with the rectified voltage. The winding is excited in advance of predetermined rotor positions by an advance period and is excited for a conduction period over each electrical half-cycle of the motor. The length of at least one of the advance period and the conduction period is defined by a waveform that varies periodically with time, and the method includes adjusting the phase of the waveform relative to the alternating voltage in response to a change in one of motor speed and RMS value of the alternating voltage. The length of the conduction period may be defined by a waveform that varies substantially as one of a triangle, trapezoid and half sinusoid over each cycle of the waveform.</p> |
