NOVELTY - The power supply system (1) has first and second converters (12-1,12-2) connected in parallel to power line, a first rechargeable battery (10-1) connected to first converter, second rechargeable batteries (10-2,10-3), and a control device (22) for controlling first and second converters and switching device (18). The control device includes a converter control unit which controls the converters in accordance with first electric power allocation ratio during first running mode and controls the converters in accordance with second electric power allocation ratio during second running mode.    USE - Power supply system for hybrid vehicle (claimed) capable of running while switching between first running mode, or charge depleting mode, of running using electric power stored for running without maintaining said electric power and second running mode, or charge sustaining mode, of running while maintaining electric power at prescribed target.    ADVANTAGE - Achieves appropriate electric power allocation in accordance with a running mode. Exhibits maximum capability.    DETAILED DESCRIPTION - The power line supplies and receives electric power between a drive force generation portion (2) for generating drive force for running upon receiving electric power from the power supply system and the power supply system. The switching device, provided between the second power storage devices and second converter, connects any of the second power storage devices to the second converter in accordance with a provided instruction. The control device also includes a switching control unit which generates instruction for sequentially switching for use of second power storage devices such that, when a state quantity indicating a charged state of the second power storage device connected to second converter is lower than a predetermined value, a remaining second power storage device of which state quantity is not lower than predetermined value is connected to second converter, and outputs instruction to switching device, a first electric power allocation ratio calculation unit which calculates the first electric power allocation ratio indicating a ratio of allocation of charge and discharge electric power between first power storage device and second power storage device connected to second converter by switching device, to be used during first running mode, such as charge depleting mode, based on a remaining electric power amount of first power storage device and second power storage devices, and a second electric power allocation ratio calculation unit which calculates the second electric power allocation ratio indicating a ratio of allocation of charge and discharge electric power between first power storage device and second power storage device connected to second converter, to be used during second running mode, such as charge sustaining mode, based on a difference between state quantity in first power storage device and second power storage device connected to second converter by switching device and a target value. An INDEPENDENT CLAIM is also included for a method of controlling a power supply system mounted on a hybrid vehicle.    DESCRIPTION OF DRAWING(S) - The drawing shows the overall block diagram of the hybrid vehicle incorporating a power supply system.    Power supply system (1)    Drive force generation portion (2)    First battery (10-1)    Second rechargeable batteries (10-2,10-3)    First and second converters (12-1,12-2)    Switching device (18)    Control device (22)