| 摘要 |
PURPOSE:To provide the subject device wherein a circuit for dividing the output voltage of a commutation auxiliary power source is provided, the thus divided voltage is applied to the commutation circuit to cause the device to stand by in a no-load running state, thereby to reduce the commutation loss. CONSTITUTION:An inverter device provided for the backup at an emergency is provided with circuits 31A and 32A for dividing the output voltage of a commutation auxiliary power source 31, and this divided voltage is applied to a commutation capacitor 27 to cause the same to stand by in a no-load running state. During the stand-by time a switch 33B is closed by the output of a switch selecting circuit 34 to lower the commutation auxiliary source voltage. In accordance with this operation the charging voltage of the commutation capacitor 27 becomes lowered correspondingly, and the commutation impulse current is also lowered. That is, during the stand-by time the inverter is driven under its low commutation function. However, since it is driven in a non-load state, the load current is zero but it is sufficient for the commutation. As a result, the commutaion loss can be reduced, and further since the power is carried constantly, the reliability on the device can be improved. |
