Inter-module battery balancing using minimum cell voltages to select battery sub-modules to power loads
For each battery sub-module in a plurality of battery sub-modules, a voltage associated with a cell in that battery sub-module is received wherein each battery sub-module in the plurality of battery sub-modules includes a plurality of cells. A battery sub-module is selected based at least in part on the received voltages and a set of one or more loads, which draws power from the selected battery sub-module and is not powered by any other battery sub-module in the plurality of battery sub-modules, is configured so that the set of loads at least temporarily does not draw power from the selected battery sub-module.
1. A method, comprising:
receiving, for each battery sub-module in a plurality of battery sub-modules, a voltage associated with a cell in that battery sub-module, wherein each battery sub-module in the plurality of battery sub-modules includes a plurality of cells;
selecting a battery sub-module from the plurality of battery sub-modules based at least in part on the received voltages by:
comparing a plurality of minimum cell voltages against a voltage threshold in order to identify any battery sub-modules with a minimum cell voltage that does not exceed the voltage threshold;
selecting one or more maximums from the plurality of minimum cell voltages in order to obtain one or more maximums of the minimum cell voltages; and
selecting said any identified battery sub-modules with a minimum cell voltage that does not exceed the voltage threshold and that do not correspond to one of the maximums of the minimum cell voltages; and
configuring a set of one or more loads, which draws power from the selected battery sub-module and is not powered by any other battery sub-module in the plurality of battery sub-modules, so that the set of one or more loads at least temporarily does not draw power from the selected battery sub-module.
2. The method recited in claim 1 , wherein configuring the set of one or more loads includes configuring the set of loads which draws power from the selected battery sub-module to be off.
3. The method recited in claim 1 , wherein selecting the battery sub-module includes:
in response to determining that there are no battery sub-modules with a minimum cell voltage that does not exceed the voltage threshold:
selecting one or more maximums from a plurality of maximum cell voltages in order to obtain one or more maximums of the maximum cell voltages; and
selecting those battery sub-modules that do not correspond to one of the maximums of the maximum cell voltages.
4. The method recited in claim 1 , further including:
determining an imbalance metric associated with a degree of imbalance between battery sub-modules in the plurality of battery sub-modules;
determining whether the imbalance metric exceeds an imbalance threshold;
in response to determining that the imbalance metric exceeds the imbalance threshold:
performing pre-charging balancing; and
charging the plurality of battery sub-modules; and
in response to determining that the imbalance metric does not exceed the imbalance threshold, charging the plurality of battery sub-modules.
5. The method recited in claim 1 , further including:
determining an imbalance metric associated with a degree of imbalance between battery sub-modules in the plurality of battery sub-modules;
determining whether the imbalance metric exceeds an imbalance threshold;
in response to determining that the imbalance metric exceeds the imbalance threshold:
performing pre-charging balancing;
charging the plurality of battery sub-modules; and
performing post-charging balancing; and
in response to determining that the imbalance metric does not exceed the imbalance threshold:
charging the plurality of battery sub-modules; and
performing post-charging balancing.
6. A system, comprising:
a processor; and
a memory coupled with the processor, wherein the memory is configured to provide the processor with instructions which when executed cause the processor to:
receive, for each battery sub-module in a plurality of battery sub-modules, a voltage associated with a cell in that battery sub-module, wherein each battery sub-module in the plurality of battery sub-modules includes a plurality of cells;
select a battery sub-module from the plurality of battery sub-modules based at least in part on the received voltages by:
comparing a plurality of minimum cell voltages against a voltage threshold in order to identify any battery sub-modules with a minimum cell voltage that does not exceed the voltage threshold;
selecting one or more maximums from the plurality of minimum cell voltages in order to obtain one or more maximums of the minimum cell voltages; and
selecting said any identified battery sub-modules with a minimum cell voltage that does not exceed the voltage threshold and that do not correspond to one of the maximums of the minimum cell voltages; and
configure a set of one or more loads, which draws power from the selected battery sub-module and is not powered by any other battery sub-module in the plurality of battery sub-modules, so that the set of one or more loads at least temporarily does not draw power from the selected battery sub-module.
7. The system recited in claim 6 , wherein configuring the set of one or more loads includes configuring the set of loads which draws power from the selected battery sub-module to be off.
8. The system recited in claim 6 , wherein selecting the battery sub-module includes:
in response to determining that there are no battery sub-modules with a minimum cell voltage that does not exceed the voltage threshold:
selecting one or more maximums from a plurality of maximum cell voltages in order to obtain one or more maximums of the maximum cell voltages; and
selecting those battery sub-modules that do not correspond to one of the maximums of the maximum cell voltages.
9. The system recited in claim 6 , wherein the memory is further configured to provide the processor with instructions which when executed cause the processor to:
determine an imbalance metric associated with a degree of imbalance between battery sub-modules in the plurality of battery sub-modules;
determine whether the imbalance metric exceeds an imbalance threshold;
in response to determining that the imbalance metric exceeds the imbalance threshold:
performing pre-charging balancing; and
charging the plurality of battery sub-modules; and
in response to determining that the imbalance metric does not exceed the imbalance threshold, charging the plurality of battery sub-modules.
10. The system recited in claim 6 , wherein the memory is further configured to provide the processor with instructions which when executed cause the processor to:
determine an imbalance metric associated with a degree of imbalance between battery sub-modules in the plurality of battery sub-modules;
determine whether the imbalance metric exceeds an imbalance threshold;
in response to determining that the imbalance metric exceeds the imbalance threshold:
performing pre-charging balancing;
charging the plurality of battery sub-modules; and
performing post-charging balancing; and
in response to determining that the imbalance metric does not exceed the imbalance threshold:
charging the plurality of battery sub-modules; and
performing post-charging balancing.
11. The system recited in claim 6 , further comprising: the plurality of battery sub-modules and the set of one or more loads.
12. A computer program product, the computer program product being embodied in a non-transitory computer readable storage medium and comprising computer instructions for:
receiving, for each battery sub-module in a plurality of battery sub-modules, a voltage associated with a cell in that battery sub-module, wherein each battery sub-module in the plurality of battery sub-modules includes a plurality of cells;
selecting a battery sub-module from the plurality of battery sub-modules based at least in part on the received voltages by:
comparing a plurality of minimum cell voltages against a voltage threshold in order to identify any battery sub-modules with a minimum cell voltage that does not exceed the voltage threshold;
selecting one or more maximums from the plurality of minimum cell voltages in order to obtain one or more maximums of the minimum cell voltages; and
selecting said any identified battery sub-modules with a minimum cell voltage that does not exceed the voltage threshold and that do not correspond to one of the maximums of the minimum cell voltages; and
configuring a set of one or more loads, which draws power from the selected battery sub-module and is not powered by any other battery sub-module in the plurality of battery sub-modules, so that the set of one or more loads at least temporarily does not draw power from the selected battery sub-module.
13. The computer program product recited in claim 12 , wherein the computer instructions for configuring the set of one or more loads include computer instructions for configuring the set of loads which draws power from the selected battery sub-module to be off.
14. The computer program product recited in claim 12 , further comprising computer instructions for:
determining an imbalance metric associated with a degree of imbalance between battery sub-modules in the plurality of battery sub-modules;
determining whether the imbalance metric exceeds an imbalance threshold;
in response to determining that the imbalance metric exceeds the imbalance threshold:
performing pre-charging balancing; and
charging the plurality of battery sub-modules; and
in response to determining that the imbalance metric does not exceed the imbalance threshold, charging the plurality of battery sub-modules.
15. The computer program product recited in claim 12 , further comprising computer instructions for:
determining an imbalance metric associated with a degree of imbalance between battery sub-modules in the plurality of battery sub-modules;
determining whether the imbalance metric exceeds an imbalance threshold;
in response to determining that the imbalance metric exceeds the imbalance threshold:
performing pre-charging balancing;
charging the plurality of battery sub-modules; and
performing post-charging balancing; and
in response to determining that the imbalance metric does not exceed the imbalance threshold:
charging the plurality of battery sub-modules; and
performing post-charging balancing.