Energy storage system

• US 7,345,454 B2
• Filed: 06/25/2004
• Issued: 03/18/2008
• Est. Priority Date: 06/27/2003
• Status: Active Grant

• Current Assignee: UCAP Power, Inc.
• Original Assignee: Maxwell Technologies Incorporated (Tesla Inc.)
• Inventors: Thrap, Guy C.
• Primary Examiner(s): Laxton; Gary L.
• Application Number:
  US10/876,441
• Publication Number:
  US 20050052169A1
• Time in Patent Office: 1,362 Days
• Field of Search: 323/220, 323/222, 323/223, 323/225, 323/265, 323/268, 323/271, 323/272, 323/282, 323/285, 323/299, 323/300, 323/350, 320/127, 320/135, 320/166, 320/167
• US Class Current: 320/135
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices

Abstract

An energy storage system is described for use in, for example, electronics systems such as a bank of computers. The disclosed energy storage systems allows the use of an efficient energy source, such as ultracapacitors, while providing a desired voltage level for an extended period of time. One embodiment of the energy storage system provides power to a load. The system includes a power module including at least one ultracapacitor adapted to store and discharge energy. The power module provides an output voltage as the ultracapacitor discharges energy. The system also includes a voltage regulator for boosting the output voltage of the power module. The voltage regulator may include a voltage converter. The voltage converter may be adapted to boost the output voltage when the output voltage falls below a predetermined threshold. The voltage converter may include a plurality of interleaving inductor circuits, each of the circuits including a switch and an inductor. The switches are adapted to be sequentially closed and opened, thereby in sequence storing energy in the inductors and discharging energy to the load.

Claims

1. A system for providing power to a load, comprising:

a module comprising at least one capacitor adapted to store and discharge energy, the module providing an output voltage as the capacitor discharges energy; and

a regulator adapted to regulate the output voltage of the module, the regulator including a discharge control circuit adapted to provide a predetermined predictable voltage profile across the load to allow for remedial action to be taken in response to the predetermined predictable voltage profile, wherein the predetermined predictable voltage profile predictably varies in accordance with a decrease in the output voltage of the module.

2. The system according to claim 1, wherein the discharge control circuit includes a comparator for comparing a voltage across the load to a reference voltage, and a power stage for controlling the regulator based on an output of the comparator.

3. The system according to claim 1, wherein the regulator is adapted to boost the output voltage when the output voltage falls below a predetermined threshold.

4. The system according to claim 1, the predetermined predictable voltage profile comprises a constant slope discharge profile.

5. The energy storage system according to claim 1, wherein the regulator includes at least one inductor circuit.

6. The system according to claim 5, wherein the regulator includes two or more interleaved inductor circuits.

7. The system according to claim 6, wherein each of the interleaving inductor circuits includes a switch and an inductor, and wherein the switches are adapted to be selectively closed and opened, thereby selectively storing energy in the inductors and discharging energy to the load.

8. The system according to claim 7, wherein the switches are controlled by the discharge control circuit.

9. The system according to claim 6, wherein each of the interleaving inductor circuits is adapted to selectively pass current to the load and bypass the load.

10. The energy storage system of claim 1, wherein the capacitor comprises an ultracapacitor.

11. The system of claim 1, wherein the system comprises a back up power system.

12. The system of claim 1, wherein the system comprises an automotive system.

28. The system of claim 1, wherein the voltage profile varies in accordance with the output voltage of the module after the output voltage reaches a threshold voltage.

13. A regulator circuit for regulating an output from an ultracapacitor power source powering a load, comprising:

an inductor circuit having at least one inductor;

switching means for selectively opening and closing the inductor circuit for selectively discharging energy to the load and storing energy in the inductors; and

a discharge regulating circuit adapted to control a predetermined predictable output voltage profile to allow for remedial action to be taken in response to the predetermined predictable output voltage profile, the discharge regulating circuit monitoring a present voltage from the power source and controlling the selective opening and closing of the inductor circuit by the switching means in response to the present voltage to provide the predetermined predictable output voltage profile such that the predetermined predictable output voltage profile predictably varies in accordance with a decrease in the present voltage.

14. A regulator circuit for regulating an output from an ultracapacitor power source powering a load, comprising:

two or more interleaved inductor circuits, each inductor circuit having at least one inductor;

switching means for selectively opening and closing each of the inductor circuits for selectively discharging energy to the load and storing energy in the inductors; and

a discharge regulating circuit adapted to control a predetermined predictable output voltage profile to allow for remedial action to be taken in response to the predetermined predictable output voltage profile, the discharge regulating circuit monitoring a present voltage from the power source and controlling the selective opening and closing of the inductor circuit by the switching means in response to the present voltage to provide the predetermined predictable output voltage profile such that the predetermined predictable output voltage profile includes a function that predictably varies in accordance with a decrease in the present voltage.

15. A method of storing energy in one or more ultracapacitor and discharging the energy to a load, comprising steps of:

monitoring a present voltage of the one or more ultracapacitor; and

providing a predetermined predictable voltage profile across the load to allow for remedial action to be taken in response to the predetermined predictable output voltage profile, wherein the predetermined predictable voltage profile predictably varies in accordance with a decrease in the present voltage.

16. The method of claim 15, comprising a step of:

operatively coupling one or more inductor to the one or more ultracapacitor; and

selectively discharging energy to the load from inductors.

17. The method of claim 15, wherein the time to reach some voltage can be predicted to occur within an accuracy of 10% or better.

18. The method of claim 15, wherein the time to reach some voltage can be predicted to occur within an accuracy of 1% or better.

29. The method of claim 15, wherein the voltage profile varies in accordance with the present voltage of the module after the present voltage reaches a threshold voltage.

19. A system for providing energy to a load, comprising

at least one ultracapacitor, the at least one ultracapacitor comprising a present voltage;

at least one inductor coupled in series with the at least one ultracapacitor; and

a circuit, wherein the circuit, the at least one ultracapacitor, and the at least one inductor are operatively coupled to provide a predetermined predictable voltage profile across the load to allow for remedial action to be taken in response to the predetermined predictable output voltage profile, wherein the predetermined predictable voltage profile varies in accordance with a decrease in the present voltage of the at least one ultracapacitor.

20. The system of claim 19, wherein system further comprises an electric motor load.

21. The system of claim 20, wherein the motor is a hybrid vehicle electric motor.

22. The system of claim 19, wherein at any given time the voltage profile describes a discharge curve of the system with an accuracy of 10% or better.

23. The system of claim 19, wherein at any given time the voltage profile describes a discharge curve of the system with an accuracy of about 1%.

24. The system of claim 20, wherein the inductor is rated to handle a current of at least 50 amps.

25. The system of claim 20, wherein source is capable of providing up to 144,000 joules of energy to the load for more than 30 seconds.

26. The system of claim 20, wherein the circuit, the at least one ultracapacitor, and the at least one inductor together comprise a back up source of energy.

27. The system of claim 20, wherein the at least one ultracapacitor and at least one inductor are connected directly.

30. The system of claim 19, wherein the voltage profile varies in accordance with the present voltage of the module after the present voltage reaches a threshold voltage.