Multiplexer and Switch-Based Electrochemical Cell Monitor and Management System and Method

• US 20080252257A1
• Filed: 04/05/2006
• Published: 10/16/2008
• Est. Priority Date: 04/05/2005
• Status: Abandoned Application

• Current Assignee: EnergyCS LLC
• Original Assignee: Energy Control Systems Engineering Incorporated (CODA Holdings, Inc.)
• Inventors: Hanssen, Greg, Nortman, Peter F., Sufrin-Disler, Daniel A.
• Application Number:
  US11/909,972
• Publication Number:
  US 20080252257A1
• Time in Patent Office: Days
• US Class Current: 320/118
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 3/0069 relating to the isolation, e.g. ground fault or leak current
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A system for monitoring a plurality of battery cells using the switch and multiplexing circuits with the plurality of monitored signal indicating the battery voltage levels for each cell by switching the measured voltage of each cell and using switching of the monitored cell voltage to selectively measure each selected signal (10).

Claims

1. A system for monitoring a plurality of electrochemical cells comprising:

switch means having an input and output;

multiplexer means for monitoring signals indicative of the cell voltage levels of a plurality of cells, and having its output electrically coupled to the input of the switch means;

selection means electrically coupled to the multiplexer means for coupling selected ones of the monitored signals to the switch means at respective times via the multiplex means, and

means for momentarily operating the switch means during a portion of each of the respective times to apply the selected signal to a measuring circuit via the output of the switch means,

whereby the switch means is used to apply a plurality of cells to the measurement circuit as different signals are selected by the multiplexer.

2. The system of claim 1 wherein the multiplexer means and includes a plurality of input pairs, each pair being coupled across a respective cell.

3. The system of claim 1 wherein the coupling arrangement of the cells to the input pairs is such that the selection means is operable to select the monitored signals for individual cells of the plurality.

4. The system of claim 1 wherein the cells are electrically coupled together to form a pack, the coupling arrangement of the input pairs being such that the selection means is operable to select monitored signals from a pair of cells that is indicative of pack voltage.

5. The system of claim 1 including isolation measurement means comprising second multiplexer means having at least one input electrically coupled to “

ground”

, and for producing a second output signal when said “

ground”

input is selected,

said selection means including means for periodically selecting said “

ground”

input of said second multiplexer,

said switch means including means for periodically applying said second output signal to the measuring circuit for isolation measurement.

6. The system of claim 1 further including

controller means for monitoring at least one of each cell'"'"'s temperature and voltage value, and

discharge means coupled across each of the cells and responsive to the controller means to discharge a cell when a monitored value of said cell is not in balance with the remaining cells.

7. The system of claim 6 wherein the discharge means includes a plurality of discharge devices coupled across a respective plurality of cells.

8. The system of claim 6 wherein the discharge means is responsive to the controller means only when the current drawn from the cell is less then a maximum permissible value.

9. The system of claim 6 wherein the discharge means is responsive to the controller means only when the cell discharge rate is less than a maximum permissible value.

10. The system of claim 6 further including memory means for allowing the balancing state of each cell to be stored to maintain operation of cell balancing when other parts of the system are shut down.

11. The system of claim 1 wherein said plurality of electrochemical cells are connected together to form a pack having positive and negative ends, and further including

a voltage divider circuit coupled to one of the positive and negative ends through said switch means for directing a scaled value of the monitored signal to the measurement circuit when the selected signal represents the pack voltage level.

12. The system of claim 1 wherein said plurality of electrochemical cells are connected together to form a pack having positive and negative ends, and further including

a voltage divider circuit coupled to one of the positive and negative ends through said switch means for directing a scaled value of the monitored signal to the measurement circuit when the selected signal represents the pack voltage level.

13. A method for monitoring a plurality of electrochemical cells comprising:

electrically coupling each of plurality of electrochemical cells to a respective multiplexer input;

coupling the output of the multiplexer to a switch that selectively couples and decouples the multiplexer output electrically to a measurement bus,

generating selection signals to the multiplexer to sequentially couple selected cells to the multiplexer output at respective time intervals

momentarily closing the switch during at least a portion of each respective time interval to electrically couple the multiplexer output to a measuring circuit,

whereby the switch applies signals for the cell plurality to the measurement circuit as different cells are selected for output by the multiplexer.

14. The method of claim 13 wherein each cell of the plurality is electrically coupled across a respective pair of multiplexer inputs so that a signal indicative of the voltage of the cell is applied to the switch when that multiplexer input pair is selected.

15. The method of claim 13 wherein the cells are electrically coupled together to form a pack, and including the step of electrically coupling the cells to the multiplexer inputs in an arrangement that permits the selection of signals indicative of pack voltage.

16. The method of claim 14 including the steps of

coupling a multiplexer input to electrical “

ground”

,

selecting said multiplexer input for electrical coupling of the resulting multiplexer output to the measurement circuit, and

selecting one multiplexer input of a cell-coupled pair for electrical coupling to the measurement circuit for isolation measurement with respect to the electrically coupled “

ground”

output from the multiplexer.

17. The method of claim 13 including the additional steps of

monitoring at least one of each cell'"'"'s temperature and voltage value, and

discharging a cell when its monitored value is not in balance with the remaining cells to thereby bring said cell into balance.

18. The method of claim 17 including the step of electrically coupling a plurality of discharge devices coupled across a respective plurality of cells.