| 摘要 |
PROBLEM TO BE SOLVED: To effectively prevent an erroneous operation of overcurrent protection due to a noise generated in sensing voltage. SOLUTION: A comparator 210 outputs a signal Vcom1 of 'H' level, when a sensing voltage Vs of an auxiliary IGBT 102 is larger than a reference voltage Vref1. A capacitor 107 of a collector voltage monitor charges a current Ica which flows at a turn-off time and an overcurrent state time. As a result, differential circuits 107 and 105 output a monitor voltage Vcs indicating a differential result; and when a main IGBT 101 is turned off at a normal operation time or the main IGBT 101 is turned on at an abnormal operation time. A comparator 211 outputs a signal Vcom2 of 'H' level, when the voltage Vcs is larger than a reference voltage Vref2. An overcurrent-deciding circuit 212 outputs a signal VT which indicates overcurrent state, only when the outputs of both the comparators 210 and 211 are at 'H' level. |
