Abstract: A power conversion device includes a conversion circuit constituted of a plurality of arm circuits and a bypass circuit. The bypass circuit includes a full-wave rectification circuit, a positive-side connection arm, and a negative-side connection arm. The full-wave rectification circuit is connected between a plurality of AC connections, a positive-side intermediate node, and a negative-side intermediate node, and configured to convert AC voltages generated at the plurality of AC connections into a DC voltage across the positive-side intermediate node and the negative-side intermediate node and output the DC voltage. The positive-side connection arm blocks a current in a direction from a positive-side DC terminal toward the positive-side intermediate node. The negative-side connection arm is connected between the negative-side intermediate node and a negative-side DC terminal and blocks a current in a direction from the negative-side intermediate node toward a negative-side DC terminal.

Abstract: A cooling fin 9 is joined to a semiconductor element 1. A resin 10 encapsulates the semiconductor element 1. A portion of the cooling fin 9 projects from a lower surface of the resin 10. A cooler 11 has an opening 12. The cooling fin 9 projecting from the resin 10 is inserted in the opening 12 of the cooler 11. The lower surface of the resin 10 and the cooler 11 are joined to each other by a joining material 13 such as an adhesive. Therefore, a reduction in the number of component parts and a reduction in weight can be achieved, and compatibility between the heat conductivity and the strength of joining can be ensured.

Abstract: A power converter includes step-up means for varying a voltage applied by a power supply to a predetermined voltage, commutating means for performing a commutation operation for allowing a current flowing through the step-up means to flow through a second path, smoothing means for smoothing a voltage related to outputs of the step-up means and the commutating means to produce power and supplying the power to a load side, and control means for performing control related to voltage varying, such as stepping up, by the step-up means and controlling the commutation operation of the commutating means on the basis of at least one of a voltage and a current related to the step-up means.