| 摘要 |
PURPOSE:To prevent an inverter failure in commutating even if a motor speed is accelerated by eliminating the increase in the commutation time of the inverter to the time or longer given by the lower limit slip frequency. CONSTITUTION:When the value of a slip frequency command omegas is not possible to cause the commutation failure of an inverter, it is selected as a slip frequency command as it is by a high order priority circuit 16, while when the slip frequency command omegas is small value to cause the commutation failure of an inverter, i.e., if omegas<omegaso, the circuit 16 selects the lower limit slip frequency omegaso, outputs it as a slip frequency command omega, and the commutation time of the inverter is limited to the commutation time decided by the lower limit slip frequency omegaso, thereby effectively obtaining a commutation time. |
