Abstract: A charge/discharge system includes a controller to control an electric power converter placed between a capacitor and a secondary battery connected in parallel. The controller includes: a request power calculation unit configured to calculate request input/output power for the electric motor generator based on current and voltage of the capacitor and input output current of the electric power converter; a capacitor discharging bias factor map configured to specify a ratio of electric power to be supplied from the capacitor to the electric motor generator to the request input power of the electric motor generator; a capacitor charging bias factor map configured to specify a ratio of electric power to be stored in the capacitor from the electric motor generator to the request output power of the electric motor generator; and a subtraction unit configured to calculate charge/discharge power of the secondary battery by subtracting, from the request input/output power, the charge/discharge power of the capacitor.

Abstract: A charge/discharge system is capable of supplying electric power to an electric motor generator and capable of charging with regenerative electric power from the electric motor generator. The charge/discharge system includes: a capacitor connected to the electric motor generator; a secondary battery connected in parallel to the capacitor; an electric power converter placed between the capacitor and the secondary battery to increase/decrease the charge/discharge voltage of the secondary battery; and a controller to control the electric power converter. If the SOC of the secondary battery is equal to or greater than a preset first setting value, the controller controls so that regenerative electric power of the electric motor generator is stored in the capacitor only, and if the SOC of the secondary battery falls below the first setting value, a part or an entire of the regenerative electric power of the electric motor generator is stored in the secondary battery.