| 摘要 |
<p>This invention provides a brushless DC motor which does not have a position sensor for detecting a rotational point of a rotor. Instead of using a position sensor, zero-crossing points of counter electromotive forces induced in the stator windings of the rotor are detected to obtain a pulse signal train. From the pulse signal train thus obtained and a slant waveform signal generated in response to the pulse signal train, a position signal with a trapezoidal waveform is formed. An electric current signal with a trapezoidal waveform is supplied to the stator windings of the rotor in response to the position signal thus formed for effecting an electric current switching of the stator windings smoothly, resulting in realizing a motor drive less in vibration and noise even when rotating at a high speed. <IMAGE></p> |
