| 摘要 |
PURPOSE:To eliminate a commutation miss by subjecting a condenser of an inverter to initial charging through utilizing a reverse voltage of a synchronous motor to satisfy commutation conditions when changing from commercial operation to inverter operation. CONSTITUTION:When changing operation according to a commercial three-phase AC power 10 to operation according to an inverter 18, a closing preparation command signal 32 is first given to a phase shift circuit 31, and a pulse of a commutation timing pulse command circuit 25 is adjusted to lead from a phase voltage of a synchronous motor 13. After that, an inverter operating breaker 20 is closed. An effect similar to reverse voltage commutation system of a commutatorless motor is then obtainable, and a condenser of the inverter 18 is put in initial charging to satisfy commutation conditions. On the other hand, a DC voltage of the inverter 18 is given to a voltage controlling circuit 30, and a DC voltage of a forward converter 16 is controlled so as not to work excessively. |
