Abstract: According to an embodiment, a power supply system for an electric motor car includes a first terminal, a second terminal, and a conversion unit. The first terminal is electrically connected to one of a power storage device and an overhead wire provided within a formation of electric motor cars. The second terminal is electrically connected to a lead wire together with a plurality of electric motors within the formation, a host power supply device, an external power supply device different from the host power supply device.

Abstract: A resonant inverter of a power supply for electric vehicle includes a first resonant capacitor and a switching element cutting off a current flowing in a resonant circuit and generates first alternating-current power from direct-current power. The transformer is included in a part of the resonant circuit, supplies the first alternating-current power generated by the resonant inverter to a first winding, and supplies second alternating-current power after conversion of the first alternating-current power to a load from a second winding. A control unit confines a difference between a resonant frequency of the resonant circuit and a switching frequency of the switching element to a predetermined range to cause that a current flowing in switching of the switching element to at least the first winding or the second winding is equal to or less than a predetermined value and to cause the resonant inverter to perform soft switching.

Abstract: According to an embodiment, a power supply system for an electric motor car includes a first terminal, a second terminal, and a conversion unit. The first terminal is electrically connected to one of a power storage device and an overhead wire provided within a formation of electric motor cars. The second terminal is electrically connected to a lead wire together with a plurality of electric motors within the formation, a host power supply device, an external power supply device different from the host power supply device.

Abstract: A resonant inverter of a power supply for electric vehicle includes a first resonant capacitor and a switching element cutting off a current flowing in a resonant circuit and generates first alternating-current power from direct-current power. The transformer is included in a part of the resonant circuit, supplies the first alternating-current power generated by the resonant inverter to a first winding, and supplies second alternating-current power after conversion of the first alternating-current power to a load from a second winding. A control unit confines a difference between a resonant frequency of the resonant circuit and a switching frequency of the switching element to a predetermined range to cause that a current flowing in switching of the switching element to at least the first winding or the second winding is equal to or less than a predetermined value and to cause the resonant inverter to perform soft switching.