| 摘要 |
PURPOSE:To pick up a frequency irrespective of the type of a motor by detecting the induced voltage of the motor, and sampling the detected voltage during one cycle to decide the frequency to be picked up. CONSTITUTION:A power interruption/power recovery detector 5d detects the power interruption or the power recovery from the presence or absence of a voltage between the output terminals of a converter 1. When a power interruption occurs and the power is recovered within approx. 1sec, the induced voltage of a motor is detected by an output voltage detector 5g, the detected voltage is sampled during one cycle to decide a frequency to be picked up. Thereafter, a microprocessor mu-CPU calculates the frequency to be picked up, and decides the phase to become the same as the phase of the motor to pick up the frequency. |
