POWER SUPPLY DEVICE FOR VEHICLE

PROBLEM TO BE SOLVED: To achieve a power supply device of a vehicle capable of preventing occurrence of overcurrent in a power source or a circuit even when the difference in potential between an electric double layer capacitor and a secondary battery is large under the restriction of a control cycle. SOLUTION: The power supply device includes: the secondary battery 10 for supplying power to a load 1 mounted in the vehicle; the electric double layer capacitor 20 connected in parallel to the secondary battery 10; a power convertor 30 intervened between the secondary battery 10 and the electric double layer capacitor 20; and a control part 40 for outputting a switching order of discharge and change of the electric double layer capacitor 20 to the power convertor 30. The control part 40 includes: a duty map 52 which sets a duty ratio of discharge and charge of the electric double layer capacitor 20 to be smaller as the difference in potential is larger based on the difference in potential between the secondary battery 10 and the electric double layer capacitor 20; and a switch control part 54 for outputting the switching order based on the duty ratio. COPYRIGHT: (C)2011,JPO&INPIT