Method for balancing ultracapacitor cells

Patent metadata

Field	Value
Publication number	US-9331500-B2
Application number	US-201213450890-A
Country	US
Kind code	B2
Filing date	Apr 19, 2012
Priority date	Apr 19, 2012
Publication date	May 3, 2016
Grant date	May 3, 2016

Abstract

A method ( 200 ) of balancing ultracapacitor cells ( 102 ) is provided. The method may measure individual ultracapacitor cell voltages, select a balancing setpoint voltage, compare an actual voltage variation within each ultracapacitor cell ( 102 ) with a voltage variation threshold, and enable a balancing element ( 104 ) associated with the ultracapacitor cell ( 102 ) if the actual voltage variation exceeds the voltage variation threshold.

First claim

What is claimed is:

1. A method of balancing ultracapacitor cells, comprising the steps of:
measuring individual ultracapacitor cell voltages;
selecting a balancing setpoint voltage;
comparing an actual voltage variation within each ultracapacitor cell with a voltage variation threshold, wherein the voltage variation threshold is a sum of an expected voltage variation and a predefined threshold voltage, the expected voltage variation being calculated based on an expected capacitance variation, the balancing setpoint voltage, and an average cell voltage; and
enabling a balancing element associated with the ultracapacitor cell if the actual voltage variation exceeds the voltage variation threshold.

2. The method of claim 1 , wherein the individual ultracapacitor cell voltages are synchronously measured at near zero current conditions.

3. The method of claim 1 , wherein the balancing setpoint voltage is selected to approximate the maximum rated voltage of the ultracapacitor cell.

4. The method of claim 1 , wherein the actual voltage variation corresponds to a difference between the measured cell voltage of one ultracapacitor cell and a minimum cell voltage.

5. The method of claim 1 , further comprising the step of disabling the balancing element after a predefined duration of time.

6. The method of claim 1 , wherein the balancing element includes at least one resistor.

7. A method of balancing ultracapacitor cells, comprising the steps of:
monitoring individual cell voltages of the ultracapacitor cells;
selecting a balancing setpoint voltage;
calculating an expected voltage variation based on an expected capacitance variation, the balancing setpoint voltage, and an average cell voltage;
comparing an actual voltage variation within each ultracapacitor cell with the expected voltage variation and a predefined threshold voltage; and
enabling a balancing resistor associated with the ultracapacitor cell if the actual voltage variation exceeds the allowed voltage variation.

8. The method of claim 7 , wherein during the step of monitoring, the individual ultracapacitor cell voltages are synchronously measured at near zero current conditions.

9. The method of claim 7 , wherein the balancing setpoint voltage is selected to approximate the maximum rated voltage of the ultracapacitor cell.

10. The method of claim 7 , wherein the actual voltage variation corresponds to a difference between the measured cell voltage of one ultracapacitor cell and a minimum cell voltage.

11. The method of claim 7 , further comprising the step of disabling the balancing resistor after a predefined duration of time.

Assignees

• Knitt Andrew A
• Kwok Wellington Ying-Wei
• Caterpillar Inc

Inventors

• Knitt Andrew A
• Kwok Wellington Ying-Wei

Classifications

• H02J7/54 Primary

  Passive balancing, e.g. using resistors or parallel MOSFETs · CPC title

• H02J7/345

  using capacitors as storage or buffering devices · CPC title

• H02J7/0016 Primary

  Electricity · mapped topic