Patent 8242627 was granted and assigned to Toyota on August, 2012 by the United States Patent and Trademark Office.
A path for charging a main battery from an external power source is established by turning on a first relay and a second relay. This charging path is provided independently of an electric path between a motor generator for generating a vehicle driving force and the main battery established by turning on a third relay. Further, an auxiliary load system including an auxiliary battery is not connected to the above-mentioned electric path, but receives operating power through a power line between the second relay and a power converter so as to be operable even with the third relay turned off.