| 摘要 |
PROBLEM TO BE SOLVED: To discriminate an abnormality of crack initiation by thermal fatigue as overheat caused by an overcurrent to enable detection and to simplify a circuit structure, in parallel with an on-off action of a semiconductor device in operation during normal operation of a power conversion apparatus. SOLUTION: A detector includes a group of one-shot circuits 31, 34, sample hold circuits 32, 35, and a differential detector 36 for detecting a temperature of an IGBT4 at an on-time or an off-time to determine temperature differences in response to a control signal a, a group of a differential detector 37, a comparator 38, and a one-shot circuit 40 for detecting the on-time t of the IGBT 4 is a set value or less, a group of a comparator 59 and a one-shot circuit 41 for detecting a current of the IGBT 4 is a set value or less, a comparator 57 for detecting that the temperature difference exceeds the set value, and an AND circuit 42 for detecting thermal fatigue of a solder layer by logical product of outputs of the one-shot circuits 40, 41 and the comparator 57. COPYRIGHT: (C)2007,JPO&INPIT
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