| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that other abnormalities cannot be detected when determining only whether or not the gate voltage Vge of a switching element S¥# is an intermediate voltage, in order to deal with an abnormality that the gate voltage Vge becomes the intermediate voltage which is lower than the voltage VH of a DC voltage source 22 but higher than a threshold voltage for bringing about the on state.SOLUTION: An operation signal g¥# of a switching element S¥# is input to a drive control unit 34. When the operation signal g¥# becomes an off operation command, a switching element 26 for charging is turned off and a switching element 32 for discharging is turned on. Furthermore, a determination is made whether or not a gate voltage Vge goes below a specified value which is equal to or lower than a threshold voltage. When it does not go below the specified value, a soft interruption switching element 54 or an off holding switching element 60 configuring a discharge path not including the switching element 32 for discharging is turned on, thus turning the switching element S¥# off forcibly. |
