| 摘要 |
PURPOSE:To perform pick-up processing securely and smoothly even with no residual voltage, by a method wherein when there is no residual voltage, auxiliary exciting voltage is applied and rotational frequency is measured. CONSTITUTION:At restarting state after instantaneous stop, an operation processing unit 32 detects existence of residual voltage. If there is no residual voltage, an inverter 21 is raised to auxiliary exciting voltage value by an operation member 32d, and stopped after a definite time. Thereby the residual voltage VH is generated in a motor 24. The rotational frequency of a motor 24 is started to be measured by the voltage VH. The voltage VH is detected by a zero cross comparator 31 and inputted to (f) measuring member 32a and frequency- measured. The measured frequency is operated in an operating member 32b and supplied as the frequency data Fs of a PWM generator 32c. The PWM generator 32c starts the inverter 21 through a base drive circuit 36, and applies exciting voltage to the motor 24. |
