Battery comprising circuitry for charge and discharge control, and method of operating a battery

• US 8,710,801 B2
• Filed: 09/23/2011
• Issued: 04/29/2014
• Est. Priority Date: 09/23/2010
• Status: Active Grant

• Current Assignee: STMicroelectronics Application GmbH (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Application GmbH (STMicroelectronics NV)
• Inventors: Schwartz, Reiner
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US13/242,649
• Publication Number:
  US 20120074898A1
• Time in Patent Office: 949 Days
• Field of Search: 320/103, 320/107, 320/112, 320/116, 320/118, 320/119
• US Class Current: 320/119
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0018 using separate charge circuits
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A battery includes a battery module that includes a plurality of submodules electrically connected in series. Each submodule comprises first and second submodule terminals and a cell. At least one submodule in each battery module is a switchable submodule comprising a submodule switching circuit. The submodule switching circuit is switchable between a first state and a second state. The submodule switching circuit electrically connects the cell of the switchable submodule between the first and second submodule terminals when the submodule switching circuit is in the first state. The submodule switching circuit provides an electrical bypass connection between the first and second submodule terminals and the cell of the switchable submodule is electrically disconnected from at least one of the first and second submodule terminals when the switching circuit is in the second state. The battery further comprises a control unit for operating the switching circuit of each module.

Claims

1. A battery, comprising:

a first battery module that includes a first plurality of submodules electrically connected to each other, each submodule including a first submodule terminal, a second submodule terminal, and a cell, wherein;

the submodules include a first switchable submodule that includes a first submodule switching circuit, the first submodule switching circuit being configured to be switched between a first state and a second state;

the first submodule switching circuit is configured to electrically couple the cell of the first switchable submodule between the first and second submodule terminals of the first switchable submodule when the submodule switching circuit is in the first state;

the first submodule switching circuit is configured to provide an electrical bypass connection between the first and second submodule terminals of the first switchable submodule and electrically decouple the cell of the first switchable submodule from at least one of the first and second submodule terminals of the first switchable submodule when the first submodule switching circuit is in the second state; and

the first battery module comprises a battery balancing circuit configured to balance a state of charge of the cells of the first plurality of submodules of the first battery module, the battery balancing circuit including an active charge balancing circuit configured to temporarily store energy from one or more of the cells of the submodules of the first battery module and to pass the stored energy to one or more other ones of the cells of the submodules of the first battery module;

a control unit configured to operate the first submodule switching circuit.

2. A battery according to claim 1, wherein the first submodule switching comprises:

a first field effect transistor having a gate, a source electrically coupled to the second submodule terminal of the switchable submodule and a negative pole of the cell of the switchable submodule, and a drain electrically coupled to the first submodule terminal of the switchable submodule; and

a second field effect transistor having a gate, a source electrically coupled to the first submodule terminal of the switchable submodule, and a drain electrically coupled to a positive pole of the cell of the switchable submodule;

wherein the control unit is configured to operate the first and second field effect transistors by applying a first gate voltage to the gate of the first field effect transistor and a second gate voltage to the gate of the second field effect transistor.

3. A battery according to claim 1, wherein the submodules include a non-switchable submodule, the cell of the non-switchable submodule being electrically coupled between the first and second submodule terminals of the non-switchable submodule.

4. A battery according to claim 1, wherein each of the submodules is a switchable submodule.

5. A battery according to claim 4, wherein the control unit is configured to detect a short circuit between poles of the battery, and switch the first switchable submodule into the second state in response to detecting the short circuit.

6. A battery according to claim 1, comprising a second battery module that includes a second plurality of submodules electrically connected to each other, each submodule of the second plurality including a first submodule terminal, a second submodule terminal, and a cell, wherein

the submodules of the second plurality include a second switchable submodule that includes a second submodule switching circuit, the second submodule switching circuit being configured to be switched between the first state and the second state;

the second submodule switching circuit is configured to electrically couple the cell of the second switchable submodule between the first and second submodule terminals of the second switchable submodule when the second submodule switching circuit is in the first state;

the second submodule switching circuit is configured to provide an electrical bypass connection between the first and second submodule terminals of the second switchable submodule and electrically decouple the cell of the second switchable submodule from at least one of the first and second submodule terminals of the second switchable submodule when the second submodule switching circuit is in the second state; and

the control unit is configured to switch at least one of the first and second switchable submodules from the first state into the second state if a voltage and/or a state of charge of cells in the battery is greater than a first threshold value during a charge process of the battery or is smaller than a second threshold value during a discharge process of the battery.

7. A battery according to claim 1, wherein:

the first battery module is one of a plurality of battery modules that each includes a corresponding plurality of submodules electrically connected to each other, each submodule of the corresponding plurality including a first submodule terminal, a second submodule terminal, and a cell;

the plurality of battery modules includes first and second subsets of battery modules, the first subset including battery modules that are not part of the second subset;

the submodules of the corresponding plurality include a corresponding switchable submodule that includes a corresponding submodule switching circuit, the corresponding submodule switching circuit being configured to be switched between the first state and the second state;

the corresponding submodule switching circuit is configured to electrically couple the cell of the corresponding switchable submodule between the first and second submodule terminals of the corresponding switchable submodule when the corresponding submodule switching circuit is in the first state;

the corresponding submodule switching circuit is configured to provide an electrical bypass connection between the first and second submodule terminals of the corresponding switchable submodule and electrically decouple the cell of the corresponding switchable submodule from at least one of the first and second submodule terminals of the corresponding switchable submodule when the corresponding submodule switching circuit is in the second state; and

the control unit is configured to switch at least one switchable submodule of the second subset of battery modules from the first state into the second state if a voltage and/or a state of charge of cells of the first subset of battery modules is greater than a first threshold value during a discharge process of the battery or is smaller than a second threshold value during a charge process of the battery.

8. A battery according to claim 1, further comprising a current sense module configured to measure a current through the battery module, wherein the control unit is configured to operate the first submodule switching circuit of the first switchable submodule based on the measured current.

9. A battery according to claim 1, wherein the first submodule switching circuit comprises at least one switching element configured to electrically connect and disconnect the cell of the first switchable submodule from at least one of the first and second submodule terminals, the at least one switching element having a breakthrough voltage of that is smaller than a sum of the voltages of all cells of the battery in a charged state.

10. A method, comprising:

operating a battery that includes a plurality of battery modules, each battery module includes a plurality of submodules electrically coupled to each other, each submodule comprising a first submodule terminal, a second submodule terminal, and at least one cell, the operating including;

selecting a subset of the plurality of submodules of at least one of the battery modules;

electrically decoupling the at least one cell of each submodule in the subset from at least one of the first and the second submodule terminal of the submodule;

providing an electrical bypass connection between the first and second submodule terminals of each submodule in the subset; and

for each battery module, balancing a state of charge of the cells of the plurality of submodules of the battery module using an active charge balancing circuit that temporarily stores energy from one or more of the cells of the submodules of the battery module and passes the stored energy to one or more other ones of the cells of the submodules of the battery module.

11. A method according to claim 10, further comprising:

determining a voltage and/or a state of charge of each of the plurality of battery modules during a discharge process of the battery;

wherein the selecting includes selecting the subset based on the determined voltage and/or state of charge, the subset including one or more battery modules having a voltage and/or state of charge that is lower than a threshold value.

12. A method according to claim 10, further comprising:

determining a voltage and/or a state of charge of each of the plurality of battery modules during a charge process of the battery;

wherein the selecting includes selecting the subset based on the determined voltage and/or state of charge, the subset including one or more battery modules having a voltage and/or state of charge that is higher than a threshold value.

13. A method according to claim 10, further comprising:

detecting a short-circuit connection between a positive and a negative pole of the battery;

wherein the selecting includes selecting the subset to comprise each cell in the battery in response to detecting the short-circuit connection.