| 摘要 |
PROBLEM TO BE SOLVED: To reduce resonance of a filter choke coil and a filter capacitor when a heating switch is ON to control a peak value of a DC voltage to be applied to an inverse converting means by impressing the predetermined voltage to the filter capacitor of a forward converter means. SOLUTION: First, a power switch NFB1 is turned ON to charge a filter capacitor C of a forward converter means to the predetermined voltage via a resistor Ro with an output of a 3-phase full-wave rectifier 11 of a DC voltage control means 10. Here, the contact of a switch SW2 turns ON with a DC voltage detecting circuit 12. Next, a heating switch SW1 is turned ON and an electromagnetic contactor 2 is also turned ON with the RY drive power supply 3 to impress a DC voltage to the filter capacitor via a filter choke coil L with an output of the 3-phase full-wave rectifier 4. Thereby, resonance of the filter capacitor C and the filter choke coil L is reduced to control the peak value of DC voltage impressed to an inverse converter means in order to reduce the size of an inverter 5 of the inverse converter means. |
