POWER SUPPLY DEVICE

A miniaturized power supply device capable of flexibly controlling a power flow from various power sources is disclosed. The power supply device includes a multi-winding transformer (20) and a plurality of power converters connected to it. First power converters include rectifier portions (1, 2, 3) and converter portions (11, 12, 13) converting DC power to AC power. AC sides of the rectifier portions are connected in series to each other and connected to an external AC power system (100). DC sides of the rectifier portions are connected to DC sides of the converter portions. During a normal state, the first power converters and a second power converter (22) are controlled to transmit power from the external AC power system to an electric storage device (32), and the first power converter and a third power converter (23) are controlled to transmit power the external AC power system to power receiving equipment (33). During power interruption, the second power converter and the third power converter are controlled to transmit power from the electric storage device to the power receiving equipment.