Abstract: Semiconductor element groups constituting a unit are mounted on a cooler heat receiving part 1 on the same plane and are adapted to radiate heat by self-cooling or cooling by wind. First and fourth semiconductor elements Q1, Q4 are arranged on the lower side of the cooler heat receiving part, second and third semiconductor elements Q2, Q3 are arranged in the middle, a first diode D5 and a second diode D6 are arranged on the upper side, the first and second semiconductor elements Q1, Q2, as well as the third and fourth semiconductor elements Q3, Q4 are each arranged in positions opposite to each other in a horizontal direction with respect to a centerline of a cooler in a vertical direction.

Abstract: A cooler of a power converting device for a railroad vehicle has heat exchanger tubes or heat radiator fins disposed to enhance the cooling performance of semiconductor devices arranged on an upper level of the multiple semiconductor devices arranged in multiple rows. Temperature detecting elements are arranged to detect temperature of the semiconductor devices arranged on a lower level on a windward side and a leeward side with respect to a traveling wind performing heat exchange with the heat radiator fins, and are arranged to detect temperature of the semiconductor devices arranged on the upper level at a center area thereof.

Abstract: A gate driving circuit for a voltage-driven power semiconductor switching device has (a) the voltage-driven power semiconductor switching device, (b) a driving circuit for supplying a drive signal to the gate electrode of the switching device, and (c) an inductance between the emitter control terminal or source control terminal of the switching device and the emitter main terminal or source main terminal of a semiconductor module. A voltage produced across the inductance is detected. The gate-driving voltage or gate drive resistance is made variable based on the detected value.

Abstract: A gate driving circuit for a voltage-driven power semiconductor switching device has (a) the voltage-driven power semiconductor switching device, (b) a driving circuit for supplying a drive signal to the gate electrode of the switching device, and (c) an inductance between the emitter control terminal or source control terminal of the switching device and the emitter main terminal or source main terminal of a semiconductor module. A voltage produced across the inductance is detected. The gate-driving voltage or gate drive resistance is made variable based on the detected value.