| 摘要 |
PURPOSE:To prevent the lowering of operational efficiency or the generation of beats, by controlling the speed of an AC motor by adjusting a duty cycle of driving pulses, and by making the wave-form distortion of voltage applied to the AC motor at that time small. CONSTITUTION:A switching transistor 6 for drive is connected in series to an AC power source 1 with an AC motor 2 and a reactor 3. A pulse generator 7 consists of a non-stabilizing multivibrator provided with an operational amplifier 8, a condenser 9, resistances 10-14, a variable resistance 15 and diodes 16, 17, and a duty cycle of driving pulses is adjusted by means of the variable resistance 15. Voltage applied to the AC motor 2 is smoothed by means of a smoothing condenser 24, and shows a sine wave form closely resembling voltage wave-form of the AC power source 1. If the duty cycle of the driving pulses changes, a period conducted to the AC motor 2 alters, and speed is controlled. |
