| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that a surge voltage may increase excessively, if a switching element S¥# is driven continuously when abnormalities occur in the active gate control function.SOLUTION: When a switching element S¥# is turned off, switching elements for discharge Pdd1, Pdd2 are turned on, at first, and then the switching element for discharge Pdd2 is turned off. Consequently, surge voltage is suppressed while reducing the switching loss as much as possible. The potential nd1 at the joint of the switching element for discharge Pdd1 and a resistor Rd1, and the potential nd2 at the joint of the switching element for discharge Pdd2 and a resistor Rd2 are compared with a threshold voltage by means of comparators 44, 46, respectively. An abnormality diagnosis section 32 diagnoses the presence or absence of abnormalities on the basis of the magnitude comparison results. |
