Power supply system

A power supply system comprising:

• a load circuit containing a rotary electrical machine coupled to a drive wheel;
• a first electrical storage device;
• a second electrical storage device having higher output weight density and lower energy weight density than the first electrical storage device;
• a power circuit which connects the load circuit, the first electrical storage device and the second electrical storage device;
• a first remaining amount parameter acquisition means for acquiring a first remaining amount parameter which increases according to a remaining amount of the first electrical storage device;
• a second remaining amount parameter acquisition means for acquiring a second remaining amount parameter which increases according to a remaining amount of the second electrical storage device;
• and
• a control device which controls flow of power between the first electrical storage device, the second electrical storage device and the rotary electrical machine, and flow of power from the first electrical storage device to the second electrical storage device, by operating the power circuit,
• wherein the control device, in a case of the second remaining amount parameter being outside a second target remaining amount range between a second lower limit value and a second upper limit value set to a value larger than the second lower limit value, controls charging and discharging of the second electrical storage device so that the second remaining amount parameter changes towards within the second target remaining amount range, and sets the second lower limit value to a larger value as the first remaining amount parameter becomes smaller.