| 摘要 |
PURPOSE:To promptly reach a command frequency by a method wherein, when a load current exceeds a limit value and a pulse-width modulated voltage which corresponds to the frequency and the phase of a residual voltage at the restart of the supply of electric power is not output, the progress of a phase is stopped. CONSTITUTION:An apparatus is constituted in such a way that a signal S2 which permits the progress stop of a phase for a pulse-width modulated voltage from a main control circuit 10 is formed, that an AND circuit 17 for the signal S2 and an overcurrent-judgment signal S1 is installed and that the logical product S3 of the overcurrent-judgment signal S1 by the signal S3 is supplied to an integrator 11. Then, when synchronization is turned on from an inverter-output stop state, a voltage- command value V*, a frequency-command value f* and an initial-phase command value theta0 are outputted from the main control circuit 10, the signal S2 which permits the progress stop of the phase for the pulse-width modulated voltage is turned off simultaneously, and the progress of a phase for the integrator 11 is not stopped by the overcurrent-judgment signal S1. As a result, it is possible to prevent an overcurrent at the turning-on of the synchronization from being moved to a regenerative state, and the residual current for an induction motor can be synchronized smoothly with an inverter output voltage. |
