Active voltage management system for energy storage device

• US 7,816,891 B2
• Filed: 11/19/2007
• Issued: 10/19/2010
• Est. Priority Date: 11/17/2006
• Status: Active Grant

• Current Assignee: UCAP Power, Inc.
• Original Assignee: Maxwell Technologies Incorporated (Tesla Inc.)
• Inventors: Johnstone, Jeffrey, Ha, Hung Q., Haman, Vlastislav, Nebrigic, Dragan
• Primary Examiner(s): Assouad; Patrick J
• Assistant Examiner(s): Fantu; Yalkew
• Application Number:
  US11/942,682
• Publication Number:
  US 20080136376A1
• Time in Patent Office: 1,065 Days
• Field of Search: 320/136
• US Class Current: 320/136
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/0034 using reverse polarity correcting or protecting circuits mechanical means of polarity protection H02J7/0045

Abstract

An active voltage management device and a method for actively managing a voltage level of an energy storage device are provided. The active voltage management device comprises: a pair of input terminals adapted to be connected to the energy storage device; a reverse polarity protection circuit coupled to the pair of input terminals; a voltage comparator circuit adapted to compare a second voltage associated with the voltage level of the energy storage device to a reference voltage and to provide an output based upon the comparison of the second voltage to the reference voltage; and a transistor adapted to operate in a linear mode to dissipate energy from the energy storage device at a substantially constant current level, wherein output of the voltage comparator circuit is adapted to activate the transistor when the second voltage is greater than or equal to the reference voltage. The method comprises: receiving an input voltage from the energy storage device; providing reverse polarity protection from the energy storage device; comparing the a second voltage associated with the input voltage from the energy storage device to a reference voltage; and conducting a transistor in a linear mode to dissipate energy from the energy storage device at a substantially constant current level when the second voltage is greater than or equal to the reference voltage.

Claims

1. An active voltage management device for actively managing a voltage level of an energy storage device, the active voltage management device comprising:

a pair of input terminals adapted to be connected to the energy storage device;

a reverse polarity protection circuit coupled to the pair of input terminals;

a voltage comparator circuit adapted to compare a second voltage associated with the voltage level of the energy storage device to a reference voltage and to provide an output based upon the comparison of the second voltage to the reference voltage;

a transistor adapted to operate in a linear mode to dissipate energy from the energy storage device at a substantially constant current level,

wherein output of the voltage comparator circuit is adapted to activate the transistor when the second voltage is greater than or equal to the reference voltage.

2. The active voltage management device according to claim 1 wherein the reverse polarity protection circuit comprises a MOSFET coupled to the pair of input terminals.

3. The active voltage management device according to claim 1 wherein the voltage comparator circuit provides a hysteresis window to prevent oscillation of the active voltage management device.

4. The active voltage management device according to claim 3 wherein the hysteresis window is adjustable via a resistor coupled to the voltage comparator circuit.

5. The active voltage management device according to claim 1 wherein the voltage comparator circuit comprises a voltage divider and the second voltage associated with the voltage level of the energy storage device comprises a fraction of the voltage level of the energy storage device provided by the voltage divider.

6. The active voltage management device according to claim 5 wherein the voltage divider comprises a resistor voltage divider.

7. The active voltage management device according to claim 1 wherein the second voltage associated with the energy storage device comprises the voltage level of the energy storage device.

8. The active voltage management device according to claim 1 further comprising an over-voltage indicator adapted to be activated by the output of the voltage comparator when the second voltage is greater than or equal to the reference value.

9. The active voltage management device according to claim 1 further comprising a light-emitting diode indicator adapted to be activated by the output of the voltage comparator circuit when the second voltage is greater than or equal to the reference voltage.

10. The active voltage management device according to claim 1 further comprising a low voltage indicator adapted to be activated by the output of the voltage comparator when the second voltage is less than or equal to the reference value.

11. The active voltage management device according to claim 1 further comprising a light-emitting diode indicator adapted to be activated by the output of the voltage comparator circuit when the second voltage is less than or equal to the reference voltage.

12. The active voltage management device according to claim 1 further comprising a control signal generating circuit comprising a transistor activated when the second voltage is greater than or equal to the reference voltage.

13. The active voltage management device according to claim 12 wherein the control signal comprises a stop charge control signal.

14. A method of actively managing a voltage level of an energy storage device, the method comprising:

receiving an input voltage from the energy storage device;

providing reverse polarity protection from the energy storage device;

comparing the a second voltage associated with the input voltage from the energy storage device to a reference voltage;

conducting a transistor in a linear mode to dissipate energy from the energy storage device at a substantially constant current level when the second voltage is greater than or equal to the reference voltage.

15. The method according to claim 14 wherein the operation of providing reverse polarity protection comprises coupling a MOSFET to a pair of input terminals.

16. The method according to claim 14 wherein the operation of comparing comprises employing a hysteresis window to prevent oscillation.

17. The method according to claim 16 wherein the hysteresis window is adjustable.

18. The method according to claim 14 wherein the second voltage comprises a fraction of the input voltage to the reference voltage obtained by applying the input voltage to a voltage divide.

19. The method according to claim 18 wherein the voltage divider comprises a resistor voltage divider.

20. The method according to claim 14 wherein the second voltage associated with the energy storage device comprises the voltage level of the energy storage device.

21. The method according to claim 14 further comprising indicating an over-voltage condition when the second voltage is greater than or equal to the reference value.

22. The method according to claim 14 further comprising indicating an over-voltage condition by activating a light-emitting diode when the second voltage is greater than or equal to the reference voltage.

23. The method according to claim 14 further comprising indicating a low voltage condition when the second voltage is less than or equal to the reference value.

24. The method according to claim 14 further comprising indicating a low voltage condition by activating a light-emitting diode when the second voltage is less than or equal to the reference voltage.

25. The method according to claim 14 further comprising generating a control signal via a transistor activated when the second voltage is greater than or equal to the reference voltage.

26. The method according to claim 25 wherein the control signal comprises a stop charge control signal.

27. The method according to claim 26 wherein the control signal is applied to a stop charge control block, the control block comprising a receiving resistor-capacitor (RC) filter, a transistor, and an optical isolator to provide an isolated control signal to a system controller.

28. An active voltage management device for actively managing a voltage level of an energy storage device, the active voltage management device comprising:

a pair of input terminals adapted to be connected to the energy storage device;

a reverse polarity protection circuit coupled to the pair of input terminals;

a voltage comparator means for comparing a second voltage associated with the voltage level of the energy storage device to a reference voltage and to provide an output based upon the comparison of the second voltage to the reference voltage;

a transistor adapted to operate in a linear mode to dissipate energy from the energy storage device at a substantially constant current level, wherein output of the voltage comparator means is adapted to activate the transistor when the second voltage is greater than or equal to the reference voltage.