ON-VEHICLE ELECTRONIC POWER CIRCUIT DEVICE

摘要

PROBLEM TO BE SOLVED: To produce an excellent output current boosting effect with a simple structure without lowering the element safety. SOLUTION: A power module 110 in which a semiconductor switching element chip 112 for electric power is fixed on a heat-radiation/heat-sink metal block 111 is placed at an outside-air current flowing portion of a vehicle so as to be cooled down by the outside-air current through a cooling member 14. The power module 110 is designed to have an increased current limit value when the vehicle speed is large and to have a decreased current limit value when the vehicle speed is small. This simplified structure can achieve an excellent output current boosting effect without lowering the element safety.