| 摘要 |
PROBLEM TO BE SOLVED: To provide a pulse width modulation converter device which can prevent failure in a backup power supply circuit without need for using an isolation transformer. SOLUTION: A converter device is provided with, at a converter 1, a control power supply circuit 16 of a switching regulator system, which is operated by both DC output of a power rectifier 2 and the output of a backup power supply circuit 17, and is operated by supplying electric power to a control circuit 12 of the converter 1. An electromagnetic contactor 18 whose opening/closing is controlled by the control circuit 12 is provided, so that only when a pulse width modulated signal is supplied to a drive circuit 15 and a switching element of the power rectifier 2 conducts a switching operation, a normally-closed contact circuit 12a is opened to turn off the electromagnetic contactor 18, and eliminates loop current which would be generated at the backup power circuit 17 by switching the switching element of the power rectifier 2. |
