Power supply equipment for motor vehicle

Power supply equipment for a motor vehicle, comprising a motor generator (2), an inverter (3) for driving said motor generator, a battery (6) and a capacitor of an electrical double layer (5), wherein the capacitor (5) is directly connected to a DC side of the inverter (3) and the battery (6) is connected in parallel with the capacitor (5) via a first switching unit (11). When an engine (1) is started up, the power stored in the capacitor (5) is used, and the switching units (11 and 12) are turned off to separate the battery (6) from the start-up of the engine.