Patent ID: 8292009

Claim:
A power supply device for supplying and receiving electric power to and from a load device via an electric power line, comprising: a plurality of power storage units that can be charged and discharge; a plurality of voltage conversion units provided correspondingly to said plurality of power storage units, each including a DC chopper circuit capable of performing bidirectional voltage conversion between a corresponding one of said power storage units and said electric power line; a control unit for controlling one of said plurality of voltage conversion units such that a voltage of said electric power line attains to a target voltage, and controlling remaining voltage conversion unit(s) such that an amount of current passage in said remaining voltage conversion unit(s) attains to a target value; and a command generation unit for generating said target voltage, and generating the target value for said amount of current passage based on request power required by said load device, wherein said command generation unit sets the target value for the amount of current passage in said remaining voltage conversion unit(s) to a prescribed nonzero value only when said request power is equal to or lower than a reference value.