Semiconductor power module and compound power module

Abstract

A semiconductor power module is configured to prevent concentration of load in a certain semiconductor power switching element. A diagnosis circuit (PC) of a module (10a or 10b) compares a sensing signal (SSE) for example, which is sent out from a sensing circuit (Se) and is proportional to the collector current of an IGBT element, with a reference voltage, and judges presence or absence of abnormality in the collector current. If abnormal, a shutdown signal (S.sub.SD) is sent out to a shutdown circuit (SD), and the IGBT element is cut off, and simultaneously an abnormality detection signal (S.sub.F01 or S.sub.F02) is sent out to the other module (10b or 10a). The diagnosis circuit (PC of the module (10b or 10a) receives the abnormality detection signal (S.sub.F01 or S.sub.F02), and sends out the shutdown signal (S.sub.SD) to the shutdown circuit (SD), thereby shutting down the IGBT element. Since the transmission timing of both shutdown signals (S.sub.SD) coincides, the both IGBT elements are cut off at the same time. Therefore, due to earlier shutdown of one IGBT element, concentration of load in the other delayed IGBT element may be avoided.