| 摘要 |
PURPOSE:To inexpensively obtain a constant speed control circuit of a semiconductor motor having good efficiency by allowing the voltage at one end of an armature coil to conincide with the prescribed voltage by the state of a power source voltage applied to an armature coil to drive a drive circuit. CONSTITUTION:When rotating speed decreases, the output of a tachometer generator 2 drops, the output of an OP amplifier 3 positively rises, the output of an OP amplifier 11 negatively drops, the output of a Hall element 14 increases, and the energizing current of an armature coil 34 increases. Accordingly, the decreases in the rotating speed is suppressed. When the rotating speed increases, the increase in the rotating speed is suppressed in the control reverse to the above operation, thereby maintaining constant speed. When the minimum value of the voltage at one end of the coil 34 becomes lower than the prescribed voltage V2, the output of the OP amplifier 36 increases, is compared by a comparator 40 with the output of a sawtooth wave generator 39, the ON period of a transistor 41 is lengthened, the voltage of a condenser 21 increases, and the voltage at one end of the coil 34 is allowed to be coincident to the prescribed voltage V2. When the minimum value increases as compared with the prescribed voltage V2, it is coincident to the prescribed voltage V2 under the control reverse to the above operation. |
