| 摘要 |
PROBLEM TO BE SOLVED: To lessen a switching loss even when the voltage of a DC power supply fluctuates. SOLUTION: Transistors 13, 14 control a gate of a MOS-input type semiconductor switching element 2a. MOSFETs 29, 30 are serially connected to the transistors 13, 14 respectively through gate resistors 19, 20 and the voltage of a DC power supply of an inverter device is detected by a voltage detecting circuit 24. The MOSFETs 29, 30 are turned off when the detected voltage is higher than a specified level and they are turned on when the detected voltage is lower than the specified level. When the voltage of the DC power supply is high, the gate of the semiconductor switching element 2a is charged by charging resistances of resistors 44, 19, 21 and discharged by discharging resistances of resistors 21, 20, 45, and therefore charging and discharging speeds are slow. On the other hand, when the voltage of the DC power supply is low, the gate is charged by the charging resistances of the resistors 19, 21 and discharged by the discharging resistances of the resistors 21, 20, and therefore charging and discharging are done rapidly and there is only a small switching loss. |
