Abstract: A vehicle power conversion device includes a two-level converter, a three-level converter and one cooling device. The two-level converter includes a capacitor, first switching devices and second switching devices. The three-level converter includes two capacitors, third switching devices, fourth switching devices and a bidirectional switch. The first and second switching devices are embedded in first power modules, and the third and fourth switching devices are embedded in second power modules. The second power modules have dielectric strength voltages at least equal to a voltage applicable to any one of the two capacitors connected in series included in the three-level converter, and the first power modules have dielectric strength voltages at least equal to a sum of a voltage applicable to any one of the two capacitors connected in series included in the three-level converter and a voltage applicable to the capacitor included in the two-level converter.

Abstract: A vehicle power conversion device includes a two-level converter, a three-level converter and one cooling device. The two-level converter includes a capacitor, first switching devices and second switching devices. The three-level converter includes two capacitors, third switching devices, fourth switching devices and a bidirectional switch. The first and second switching devices are embedded in first power modules, and the third and fourth switching devices are embedded in second power modules. The second power modules have dielectric strength voltages at least equal to a voltage applicable to any one of the two capacitors connected in series included in the three-level converter, and the first power modules have dielectric strength voltages at least equal to a sum of a voltage applicable to any one of the two capacitors connected in series included in the three-level converter and a voltage applicable to the capacitor included in the two-level converter.

Abstract: According to one embodiment, a natural circulation type cooling apparatus includes a heat receiver with a heat receiving surface on which an exothermic body is mounted, and containing therein a coolant, a condenser on a horizontally lateral side of the heat receiver, a radiator on a horizontally lateral side of the heat receiver and on a vertically downward side of the condenser, a vapor conduit configured to feed vapor of the coolant to an inlet of the condenser, a condensed liquid conduit configured to feed a condensed coolant from an outlet of the condenser to an inlet of the heat receiver, a coolant conduit configured to feed the coolant to an inlet of the radiator, and a circulation conduit configured to feed the coolant from an outlet of the radiator to the inlet of the heat receiver.