Energy storage device stack balancing using switched inductor background

1. An energy storage stack balancing circuit for balancing a set of serially connected energy storage devices, the balancing circuit comprising:

an electronic switching system that controls a delivery of energy into and out of an inductor; and

a controller configured to control the electronic switching system so as to cause energy to be transferred from a selected one or more of the serially connected energy storage devices into the inductor, and then out of the inductor concurrently into a plurality of other energy storage devices in the serially connected energy storage devices.

2. The energy storage stack balancing circuit of claim 1 , wherein each of the serially connected energy storage devices includes at least one of a battery or a capacitor.

3. The energy storage stack balancing circuit of claim 1 , wherein the electronic switching system includes four electronic switches.

4. The energy storage stack balancing circuit of claim 3 , wherein:

the inductor has a first and a second connection;

two of the electronic switches are connected to the first connection of the inductor; and

the other two of the electronic switches are connected to the second connection of the inductor.

5. The energy storage stack balancing circuit of claim 1 , wherein the controller is further configured to cause energy to be transferred from one of the energy storage devices into the inductor and then out of the inductor and into a different one, a subset, or all, of the energy storage devices.

6. The energy storage stack balancing circuit of claim 1 , wherein the controller is further configured to cause energy to be transferred from all of the serially connected energy storage devices into the inductor and then out of the inductor and into a respective one, or a subset, of the serially connected energy storage devices.

7. The energy storage stack balancing circuit of claim 1 , wherein the controller causes energy to be transferred:

during a first time period, from a first of the serially connected energy storage devices into the inductor and then out of the inductor and into a first plurality of energy storage devices; and

during a second time period, from a second of the serially connected energy storage devices into the inductor and then out of the inductor and into a second plurality of energy storage devices.

8. The energy storage stack balancing circuit of claim 1 , wherein the controller is further configured to cause energy to be transferred:

during a first time period, from the selected one or more of the serially connected energy storage devices into the inductor and then out of the inductor and into the plurality of energy storage devices and, during a second time period, from one or more of the plurality of energy storage devices into the inductor and then out of the inductor and into the selected one or more of the serially connected energy storage devices.

9. The energy storage stack balancing circuit of claim 1 , wherein the controller is further configured to cause energy to be transferred during a first time period, from all of the serially connected energy storage devices into the inductor and then out of the inductor and into one or a subset of the serially connected energy storage devices and, during a second time period, from the one or the subset of the serially connected energy storage devices into the inductor and then out of the inductor and into all of the serially connected energy storage devices.

10. The energy storage stack balancing circuit of claim 1 , wherein the controller is further configured to cause energy to be transferred:

during a first time period, from the selected one or more devices of the serially connected energy storage devices into the inductor and then out of the inductor and into the plurality of energy storage devices and, during a second time period, from one or more of the plurality of energy storage devices into the inductor and then out of the inductor and into the selected one or more devices;

during a third time period, from a subset of the serially connected energy storage devices into the inductor and then out of the inductor and into the plurality of energy storage devices and, during a fourth time period, from one or more of the plurality of energy storage devices into the inductor and then out of the inductor and into the subset of the serially connected energy storage devices; and

during a fifth time period, from all of the serially connected energy storage devices into the inductor and then out of the inductor and into one or a subset of the serially connected energy storage devices and, during a sixth time period, from the one or the subset of the serially connected energy storage devices into the inductor and then out of the inductor and into all of the serially connected energy storage devices.

11. The energy storage stack balancing circuit of claim 1 , wherein the circuit includes a separate inductor and a separate electronic switching system associated with each of the energy storage devices.

12. The energy storage stack balancing circuit of claim 1 , wherein the electronic switching system includes two electronic switches and two diodes.

13. The energy storage stack balancing circuit of claim 12 , wherein the inductor is connected to the two electronic switches and to the two diodes.

14. The energy storage stack balancing circuit of claim 1 , wherein the circuit excludes a transformer.

15. An energy storage stack balancing system, comprising:

means for selecting an energy storage device from a set of energy storage devices means that are coupled to each other; and

means for transferring energy from the selected energy storage device via an inductor means concurrently to a plurality of other energy storage devices in the set of energy storage devices means.

16. The system of claim 15 further comprising:

means for transferring the energy from the selected energy storage device to the inductor during a first time period; and

means for transferring the energy from the inductor concurrently to the plurality of energy storage devices during a second time period.

17. The system of claim 15 , wherein the set of energy storage devices are serially connected.

18. The system of claim 15 further comprising means for transferring energy from all of the set of energy storage devices into the inductor and then out of the inductor and into a respective one, or a subset, of the set of energy storage devices.

19. The system of claim 15 further comprising means for transferring energy from at least one of the plurality of the other energy storage devices to the selected energy storage device.

20. A machine-implemented method, comprising:

selecting an energy storage device from a set of energy storage devices that are coupled to each other; and

transferring energy from the selected energy storage device via an inductor concurrently to a plurality of other energy storage devices in the set of energy storage devices.

21. The method of claim 20 further comprising:

transferring the energy from the selected energy storage device to the inductor during a first time period; and

transferring the energy from the inductor concurrently to the plurality of energy storage devices during a second time period.

22. The method of claim 20 , wherein the set of energy storage devices are serially connected.

23. The method of claim 20 further comprising transferring energy from all of the set of energy storage devices into the inductor and then out of the inductor and into a respective one, or a subset, of the set of energy storage devices.

24. The method of claim 20 further comprising transferring energy from at least one of the plurality of the other energy storage devices to the selected energy storage device.