ELECTRIC POWER SOURCE SYSTEM FOR ELECTRICALLY DRIVEN VEHICLE AND ITS CONTROL METHOD

摘要

An electric power source system includes a main electric storage device (BA) and a plurality of sub-electric storage devices (BB1, BB2). A converter (12B) is connected with a selected one of the sub-electric storage devices (BB1, BB2) and carries out a bidirectional voltage conversion between the selected sub-electric storage device and an electric power supply line (PL2). In a compulsory switching region where the SOC of the selected sub-electric storage device in operation is lower than the lower limit judgment value, switch processing of the sub-electric storage device takes place compulsorily regardless of a vehicle condition. In a switching permission region where the SOC is higher than that of the compulsory switching region, a switching request takes place on the basis of a vehicle condition at the time judged to be right in a state not to influence the drivability of the vehicle.