| 摘要 |
PURPOSE:To smoothly pick up when no remaining voltage exists by preliminarily exciting for a predetermined time when no remaining voltage exists, and measuring a rotating frequency. CONSTITUTION:The presence or absence of a remaining voltage is detected at recovery time after power is interrupted. When no remaining voltage exists, the frequency data Fs of a PWM generator 32c is set to STOP-F (maximum frequency) at power interruption time, an inverter 21 is started to be preliminarily excited. Thereafter, the inverter 21 is interrupted at gate to stop the inverter 21 for a predetermined time. At this time, a remaining voltage is generated in a motor 24. The frequency of the rotating speed of the motor 24 is measured by the remaining voltage. The measured frequency is calculated by a calculator 32b to supply as the frequency data Fs of the PWM generator 32c. |
