Circuit for rendering energy storage devices parallelable

• US 8,922,063 B2
• Filed: 04/27/2011
• Issued: 12/30/2014
• Est. Priority Date: 04/27/2011
• Status: Expired due to Fees

• Current Assignee: Engie Storage Services NA LLC (ENGIE SA)
• Original Assignee: Green Charge Networks LLC (ENGIE SA)
• Inventors: Taddeo, Stephen Randolph
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): SHIAO, DAVID A
• Application Number:
  US13/095,270
• Publication Number:
  US 20120274145A1
• Time in Patent Office: 1,343 Days
• Field of Search: None
• US Class Current: 307/82
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H02J 1/12 Parallel operation of dc generators with converters, e.g. with mercury-arc rectifier
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A circuit for rendering an energy storage device parallelable comprised of an energy storage device connected to a power adapter that converts the potential of the energy storage device into a potential that follows a predetermined function of the state of charge of the energy storage device. When multiple assemblies are paralleled, they may be charged and discharged as a whole with individual storage devices maintaining equal states of charge. The energy storage devices can be batteries with different cell counts, configurations, and energy discharge profiles. In some cases, the power adapters are comprised of DC to DC converters and system controllers that are used to translate each battery'"'"'s energy discharge profile into a user-determined energy discharge profile that is a predictable function of the battery'"'"'s state of charge and independent of temperature or other external conditions.

Claims

1. A circuit rendering an energy storage device parallelable, the circuit comprising:

(a) an energy storage device having a state of charge and a source connection with a source potential; and

(b) a power adapter having a first connection electrically connected to the source connection and a second connection having a terminal potential,

wherein while the energy storage device is discharged using the power adapter, the power adapter converts between the source potential and the terminal potential such that the terminal potential follows a static, monotonic voltage function proportional to the state of charge of the energy storage device;

wherein while the energy storage device is charged using the power adapter, the power adapter converts between the terminal potential and the source potential such that the source potential follows a function proportional to the state of charge of the energy storage device.

2. The circuit of claim 1, wherein the power adapter comprises:

(a) a DC to DC converter having a first connection, a second connection, and a third connection, the first connection being electrically connected to the source connection, and the second connection having a terminal potential; and

(b) a system controller having a controller connection electrically connected to the third connection of the DC to DC converter,

wherein the system controller directs the DC to DC converter to convert between the source potential and the terminal potential by following a static, monotonic voltage function proportional to the state of charge of the energy storage device.

3. The circuit of claim 2, wherein the system controller directs the DC to DC converter to convert between the source potential and the terminal potential by supplying a duty factor to the DC to DC converter.

4. The circuit of claim 3, wherein the system controller adjusts the duty factor supplied to the DC to DC converter by:

(a) calculating the state of charge of the energy storage device,

(b) calculating a reference voltage by comparing the state of charge to information regarding a relationship between the state of charge and target energy storage device properties,

(c) using a feedback control loop to determine the adjustment to the duty factor by comparing the reference voltage to a measurement of the present terminal potential, and,

(d) outputting an adjusted duty factor to the DC to DC converter, whereby the DC to DC converter converts between the source potential and the terminal potential according to the adjusted duty factor.

5. The circuit of claim 4, wherein the voltage function is a linear function of the state of charge of the energy storage device connected to the power adapter.

6. The circuit of claim 4, wherein the voltage function is a function to approximate an energy discharge profile of an energy storage device selected from a group consisting of real and theoretical energy storage devices.

7. The circuit of claim 3, wherein the system controller is a pulse width modulation controller.

8. The circuit of claim 1, further comprising a start switch electrically connected to the power adapter, wherein the power adapter will not make the terminal potential available for access unless the start switch is closed.

9. The circuit of claim 1, wherein the energy storage device is selected from a group consisting of batteries, flywheels, capacitive devices, pumped hydro, superconductive magnetic energy storage, and combinations thereof.

10. The circuit of claim 1 further comprising a user interface connection, wherein the second connection of the power adapter is electrically connected to the user interface connection.

11. The circuit of claim 10, wherein the second connection of the power adapter is electrically connected to the user interface connection in parallel with an additional energy storage device having an additional source potential, wherein the additional energy storage device is connected to the user interface connection via an additional power adapter that converts the additional source potential into an additional terminal potential, wherein the additional terminal potential closely resembles output of the static, monotonic voltage function proportional to the state of charge of the energy storage device connected to the first connection of the power adapter.

12. The circuit of claim 1 further comprising an inverter having a DC connection, wherein the second connection of the power adapter is electrically connected to the DC connection.

13. The circuit of claim 1, wherein the second connection of the power adapter is electrically connected to a user interface connection in parallel with a parallel circuit element having a parallel source potential, wherein the parallel source potential closely resembles output of the static, monotonic voltage function proportional to the state of charge of the energy storage device connected to the first connection of the power adapter.

14. The circuit of claim 13, wherein the parallel circuit element is selected from a group consisting of one or more energy storage devices, one or more energy generation devices, a utility distribution grid, an additional energy storage device connected to an additional power adapter, and combinations thereof.

15. The circuit according to claim 1, wherein the second connection of the power adapter is electrically connected to a load and the energy storage device is discharged to supply power to the load.

16. A method of connecting and converting a plurality of energy storage devices in a parallel topology, the method comprising the steps of:

(a) connecting at least two energy storage devices to at least two DC to DC converters, such that each energy storage device is connected to a different DC to DC converter, and wherein each of the energy storage devices has a state of charge and an energy storage device potential;

(b) connecting at least two system controllers to the DC to DC converters, such that each DC to DC converter is connected to a different system controller without the system controllers intercommunicating; and

(c) while the energy storage devices are discharged using the at least two DC to DC converters, instructing the system controllers to direct the DC to DC converters to produce an output potential that follows a static, monotonic voltage function proportional to the state of charge of the energy storage devices, wherein the energy discharge profiles of each of the DC to DC converters are the same; and

while the energy storage devices are charged using the at least two DC to DC converters, instructing the system controllers to direct the DC to DC converters to produce an output potential that follows a function proportional to the state of charge of the energy storage device.

17. The method of claim 16, wherein the static, monotonic voltage function is a function approximating an energy discharge profile of an energy storage device selected from a group consisting of real and theoretical energy storage devices.

18. A circuit rendering an energy storage device parallelable, the circuit comprising:

(a) an energy storage device having a state of charge and a source connection with a source potential;

(b) a DC to DC converter having a first connection electrically connected to the source connection, the DC to DC converter having second connection having a terminal potential, the DC to DC converter having a third connection;

(c) a system controller connected to the third connection of the DC to DC converter;

wherein while the energy storage device is discharged using the DC to DC converter, the DC to DC converter converts between the source potential and the terminal potential such that the terminal potential follows a static, monotonic voltage function of the state of charge of the energy storage device;

wherein while the energy storage device is charged using the DC to DC converter, the DC to DC converter converts between the terminal potential and the source potential such that the source potential follows a function proportional to the state of charge of the energy storage device;

wherein the system controller directs the DC to DC converter to convert between the source potential and the terminal potential by supplying a duty factor to the DC to DC converter, and the system controller adjusts the duty factor supplied to the DC to DC converter by;

(a) calculating the state of charge of the energy storage device,

(b) calculating a reference voltage by comparing the state of charge to information regarding a relationship between the state of charge and target energy storage device properties,

(c) using a feedback control loop to determine the adjustment to the duty factor by comparing the reference voltage to a measurement of the present terminal potential, and

(d) outputting an adjusted duty factor to the DC to DC converter, whereby the DC to DC converter converts between the source potential and the terminal potential according to the adjusted duty factor.

19. The circuit of claim 18, wherein the voltage function is a linear function of the state of charge of the energy storage device connected to the power adapter.

20. The circuit of claim 18, wherein the voltage function is a function to approximate an energy discharge profile of an energy storage device selected from a group consisting of real and theoretical energy storage devices.