| 摘要 |
PURPOSE:To necessitate no rotational frequency detector and control an induction motor with economical composition, by estimating slip frequency without using the rotational frequency detector, and by performing arithmetic on rotational frequency. CONSTITUTION:The input of the detected values of the input voltage VDC and the input current IDC of an inverter 3, the phase current ia, ib of IM input, and its line-to-line voltage v1, to a slip frequency arithmetic unit 6 from each sensor is provided, and the input of an IM frequency command value omega to the unit 6 from a rotational frequency control circuit 7 is provided, and a slip frequency estimate omegaS is computed. By the rotational frequency control circuit 7, based on a rotational frequency command value omegam, the IM primary-frequency command value omega and the command value i1 (or v1) of IM primary current (or voltage) are computed. The input of these values to the PWM circuit 8 of a following stage is provided and is pulse-width-modulated, and the input to the inverter 3 through an inverter driving circuit 9 is provided. |
