Abstract: A power storage system supplies electric power to a load, and includes: a secondary battery; a capacitor connected in parallel to the secondary battery; and a controller performing control to prioritize charging and discharging of the capacitor over charging and discharging of the secondary battery.

Abstract: In a power storage system, a bidirectional DC-DC converter is set into mode for charging a secondary battery with electricity when a first state of charge (SOC) of the secondary battery is larger than a minimum value of the first SOC, and a second SOC of the capacitor is smaller than a maximum value of the second SOC, and the converter is set into mode for discharging electricity from the secondary battery when the first SOC is smaller than a maximum value of the first SOC, and the second SOC is larger than a minimum value of the second SOC. Based on an internal resistance of the secondary battery, the second SOC, a voltage of a direct current link in case of no load connected to DC link, and an error in a current on a direct current link side, a conduction ratio (D) of the converter is calculated.

Abstract: A power storage system supplies electric power to a load, and includes: a secondary battery; a capacitor connected in parallel to the secondary battery; and a controller performing control to prioritize charging and discharging of the capacitor over charging and discharging of the secondary battery.

Abstract: In a power storage system, a bidirectional DC-DC converter is set into mode for charging a secondary battery with electricity when a first state of charge (SOC) of the secondary battery is larger than a minimum value of the first SOC, and a second SOC of the capacitor is smaller than a maximum value of the second SOC, and the converter is set into mode for discharging electricity from the secondary battery when the first SOC is smaller than a maximum value of the first SOC, and the second SOC is larger than a minimum value of the second SOC. Based on an internal resistance of the secondary battery, the second SOC, a voltage of a direct current link in case of no load connected to DC link, and an error in a current on a direct current link side, a conduction ratio (D) of the converter is calculated.

Abstract: A battery module charging system includes a power transmitting device, including a primary coil configured to transmit AC power, and a power receiving unit, including a secondary coil configured to receive the AC power transmitted from the primary coil by electromagnetic induction. The power receiving unit is configured to convert the received AC power into DC power. A positioning mechanism is configured to allow the power transmitting device to be detachably attached to the power receiving unit and to position the primary and secondary coils such that the coils are allowed to be electromagnetically coupled to each other when the power transmitting device is attached to the power receiving unit. Further, a selection circuitry is configured to selectively charge a plurality of cells in a battery module with the DC power. The plurality of cells, the cells being secondary batteries, are connected to each other in a series.