Direct-current power source apparatus

• US 8,581,557 B2
• Filed: 03/15/2011
• Issued: 11/12/2013
• Est. Priority Date: 03/17/2010
• Status: Expired due to Fees

• Current Assignee: Shin-Kobe Electric Machinery Company Limited (Resonac Holdings Corp.)
• Original Assignee: Shin-Kobe Electric Machinery Company Limited (Resonac Holdings Corp.)
• Inventors: Amano, Masahiko, Iida, Yukio, Hama, Yoshiki, Yamada, Keizo, Kanoh, Mitsuyoshi
• Primary Examiner(s): Fantu, Yalkew
• Application Number:
  US13/048,267
• Publication Number:
  US 20110227540A1
• Time in Patent Office: 973 Days
• Field of Search: 320/135
• US Class Current: 320/135
• CPC Class Codes: B60L 50/15 with additional electric power supply with capacitors charged by engine-driven generators B60L50/40; with batteries charged by engine-driven generators B60L50/61
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: B60L 53/00 Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
• CPC Class Codes: B60L 58/24 for controlling the temperature of batteries
• CPC Class Codes: B60L 7/16 for vehicles comprising converters between the power source and the motor
• CPC Class Codes: F02N 11/0866 comprising several power sources, e.g. battery and capacitor or two batteries
• CPC Class Codes: F02N 2011/0885 Capacitors, e.g. for additional power supply
• CPC Class Codes: H02J 7/0024 Parallel/serial switching of connection of batteries to charge or load circuit
• CPC Class Codes: H02J 7/007192 in response to temperature
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: H02J 9/02 in which an auxiliary distribution system and its associated lamps are brought into service
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles

Abstract

A direct-current power source apparatus in which a lithium-ion capacitor unit is used as an electric storage system and which can fully utilize the lithium-ion capacitor unit and maintain the supply of electricity to a load is provided. An electric storage system includes a lithium-ion capacitor unit and a lead-acid battery connected in parallel with a load, and a voltage detecting section that detects the voltage of the lithium-ion capacitor unit. When the voltage detecting section detects that the voltage of the lithium-ion capacitor unit has reached a unit lower-limit voltage, a control circuit outputs a conduction signal for causing a switching circuit to get into a conductive state. When the switching circuit gets into a conductive state, the secondary battery supplies an electric power to a motor. At this time, the secondary battery charges the lithium-ion capacitor unit.

Claims

1. A direct-current power source apparatus comprising:

an electric storage system capable of being charged and discharging an electricity to a load to supply a direct-current power to the load, wherein

the electric storage system comprises;

a lithium-ion capacitor unit connected in parallel with the load;

a secondary battery connected in parallel with the load;

a voltage detecting section for detecting a voltage of the lithium-ion capacitor unit; and

a changeover circuit that electrically disconnects the secondary battery from the load before the voltage detecting section detects a unit lower-limit voltage of the lithium-ion capacitor unit, and that connects the secondary battery in parallel with the load and the lithium-ion capacitor unit when the voltage detecting section detects the unit lower-limit voltage.

2. The direct-current power source apparatus according to claim 1, wherein:

one of paired input/output portions of the lithium-ion capacitor unit, which are connected to paired input portions of the load, and one of paired input/output portions of the secondary battery are electrically connected to each other; and

the changeover circuit includes a controllable switching circuit that is disposed between the other of the paired of input/output portions of the lithium-ion capacitor unit and the other of the paired of input/output portions of the secondary battery and that gets into a conductive state when the voltage detecting section detects the unit lower-limit voltage.

3. The direct-current power source apparatus according to claim 2, the electric storage system further comprising:

a diode with an anode connected to the other of the paired input/output portions of the lithium-ion capacitor unit and with a cathode connected to the input/output portion as a positive terminal of the secondary battery.

4. The direct-current power source apparatus according to claim 1, wherein

the voltage detecting section is powered by the secondary battery.

5. The direct-current power source apparatus according to claim 1, wherein:

one of paired input/output portions of the lithium-ion capacitor unit, which are connected to a pair input portions of the load, and one of paired input/output portions of the secondary battery are electrically connected to each other; and

a unidirectional conductive device is electrically connected between the other of the pair of input/output portions of the lithium-ion capacitor unit and the other of the pair of input/output portions of the secondary battery, the unidirectional conductive device getting into a conductive state when the voltage of the lithium-ion capacitor unit falls down to or below the unit lower-limit voltage, and the unidirectional conductive device functioning as the voltage detecting section and the changeover circuit.

6. The direct-current power source apparatus according to claim 5, wherein

the unidirectional conductive device comprises one or more constant-voltage diodes.

7. The direct-current power source apparatus according to claim 1, wherein

the lithium-ion capacitor unit includes a plurality of lithium-ion capacitors connected in series with each other and a plurality of voltage equalizing circuits respectively connected in parallel with the plurality of lithium-ion capacitors.

8. The direct-current power source apparatus according to claim 1, further comprising:

a regeneration circuit that charges the lithium-ion capacitor unit and/or the secondary battery of the electric storage system using a regenerated current generated by the load when the load is in a regenerating state.

9. The direct-current power source apparatus according to claim 1, wherein

when the secondary battery is connected in parallel with the load and the lithium-ion capacitor unit, the changeover circuit initially takes a first circuit configuration in which the secondary battery is connected in parallel with the load and the lithium-ion capacitor unit via a first discharging circuit including current limiting means, and thereafter takes a second circuit configuration in which the secondary battery is connected in parallel with the load and the lithium-ion capacitor unit via a second discharging circuit not including the current limiting means when it is detected that the voltage of the lithium-ion capacitor unit has risen to a first set voltage that is higher than the unit lower-limit voltage or that the voltage of the lithium-ion capacitor unit has decreased to a second set voltage that is lower than the unit lower-limit voltage.

10. The direct-current power source apparatus according to claim 9, wherein

the second discharging circuit comprises a short circuit that short-circuits the current limiting means in the first discharging circuit.

11. The direct-current power source apparatus according to claim 9, further comprising:

a charging circuit that is brought into an operating state to charge the secondary battery when a charging voltage is applied to the lithium-ion capacitor unit by an external charger.

12. The direct-current power source apparatus according to claim 11, wherein

the charging circuit includes a switching circuit so that the secondary battery is charged when the switching circuit gets into a conductive state.

13. The direct-current power source apparatus according to claim 11, wherein

the charging circuit includes a DC/DC converter that decreases the charging voltage to a voltage suitable for charging the secondary battery.

14. The direct-current power source apparatus according to claim 13, further comprising:

temperature detecting means for detecting an ambient temperature, wherein

the DC/DC converter decreases the voltage suitable for charging the secondary battery when the temperature detected by the temperature detecting means becomes higher than a predetermined reference upper-limit temperature, and increases the voltage suitable for charging the secondary battery when the temperature detected by the temperature detecting means becomes lower than a predetermined reference lower-limit temperature.

15. The direct-current power source apparatus according to claim 9, further comprising:

a charging circuit that includes one or more diodes and that, when a charging voltage is applied to the lithium-ion capacitor unit by an external charger, decreases the charging voltage to a voltage suitable for charging the secondary battery to apply the resulting voltage to the secondary battery.

16. The direct-current power source apparatus according to claim 15, wherein

the charging circuit includes a switching circuit so that the secondary battery is charged when the switching circuit gets into a conductive state.

17. The direct-current power source apparatus according to claim 9, wherein

the first set voltage is determined by subtracting an allowable difference voltage from a voltage between the paired input/output portions of the secondary battery, the allowable difference voltage allowing a current discharged from the secondary battery to be prohibited from becoming an overcurrent.

18. The direct-current power source apparatus according to claim 17, wherein

the allowable difference voltage is determined as the product of the sum of an internal resistance of the lithium-ion capacitor unit and an internal resistance of the secondary battery and a maximum discharging current of the secondary battery.

19. A transfer apparatus comprising the direct-current power source apparatus according to claim 1 as a power source.

20. A method of charging the lithium-ion capacitor unit and the secondary battery in the direct-current power source apparatus according to claim 1 using a common direct-current charging power source, the method comprising the steps of:

charging the lithium-ion capacitor unit with the secondary battery electrically disconnected from the direct-current charging power source; and

charging the secondary battery with the lithium-ion capacitor unit electrically disconnected from the direct-current charging power source after the lithium-ion capacitor unit is completely charged.