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 power converter of the present invention is connected between a direct current power source and controls power to a load by switching equipment. The converter is equipped with a first conductor for connecting a negative pole of the power converter and the switching equipment, and a second conductor for connecting a housing of the power converter and the negative pole of the power converter to the first conductor through a resistor.

Abstract: A power converter of the present invention is connected between a direct current power source and controls power to a load by switching equipment. The converter is equipped with a first conductor for connecting a negative pole of the power converter and the switching equipment, and a second conductor for connecting a housing of the power converter and the negative pole of the power converter to the first conductor through a resistor.

Abstract: A power converter of the present invention is connected between a direct current power source and controls power to a load by switching equipment. The converter is equipped with a first conductor for connecting a negative pole of the power converter and the switching equipment, and a second conductor for connecting a housing of the power converter and the negative pole of the power converter to the first conductor through a resistor.

Abstract: A power converter of the present invention is connected between a direct current power source and controls power to a load by switching equipment. The converter is equipped with a first conductor for connecting a negative pole of the power converter and the switching equipment, and a second conductor for connecting a housing of the power converter and the negative pole of the power converter to the first conductor through a resistor.