| 摘要 |
PURPOSE:To miniaturize a motor, to make it thin-shaped and to cut down its cost, by subjecting counter electromotive force produced by a stator coil to waveform processing and by making it a rotating position signal of a rotor. CONSTITUTION:The operation sequence of a DC brushless motor is divided into a starting stage S where the motor starts at fully low speed, and accelerating stage E and a subsequent steady rotating stage G. The control of the starting stage S is performed by waveform-processing the reference pulse to generate low speed rotating field through stator coils 12, 13 and 14 one after another. The frequency of the reference pulse is then slowly and gradually increased. Along with this, the period of waveform supplied to transistors Q1-Q6 becomes shorter, the rotating field of a stator is accelerated and the rotating speed of a rotor is increasing along the slanting portion of the accelerating stage E. Thus, when the revolution gets to the designated speed of rotation N0, it is detected and the mode is changed over. That is, the amplified output waveform obtained by waveform-processing the counter electromotive force of the stator coil along with the rotation of the motor is substituted for the rotating position signal of rotor. The waveform will thereby get in the steady rotating stage from a switching point 15. |
