Electrochemical cell monitoring and balancing circuit with self-diagnostic feature

• US 9,568,555 B2
• Filed: 12/06/2011
• Issued: 02/14/2017
• Est. Priority Date: 12/06/2010
• Status: Expired due to Fees

• Current Assignee: Exergonix, Inc.
• Original Assignee: CODA Asset Holding Corporation
• Inventors: Sufrin-Disler, Daniel A., Mcgulpin, Patrick J., Nortman, Peter Fredrick, Weicker, Phillip John
• Primary Examiner(s): Ngo, Brian
• Application Number:
  US13/312,025
• Publication Number:
  US 20120139553A1
• Time in Patent Office: 1,897 Days
• Field of Search: 320/106, 320/118, 320/132, 320/134, 320/145, 320/165
• US Class Current: 1/1
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• 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: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 50/569 Constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals battery terminal connectors with integrated measuring arrangements G01R31/364
• CPC Class Codes: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0069 Charging or discharging for charge maintenance, battery initiation or rejuvenation
• CPC Class Codes: H02J 9/002 in which a reserve is maintained in an energy source by disconnecting non-critical loads, e.g. maintaining a reserve of charge in a vehicle battery for starting an engine
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/92 Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles

Abstract

A system and method for measuring a voltage of electrochemical cells of a pack. The system includes circuit elements individually associated with respective electrochemical cells of the pack and having electrical characteristics that are different such that individual electrochemical cells can be distinguished from one another. The system also includes a measurement circuit configured to measure the voltage of the electrochemical cells and to identify an electrochemical cell being measured based on an electrical characteristic of a circuit element associated with the electrochemical cell. Various self-diagnostic techniques are described, as well as techniques for measuring sense resistance, reducing sense resistance, and measuring changes in voltage of a cell over time.

Claims

1. A measurement system for a pack of electrochemical cells, the measurement system comprising:

circuit elements individually electrically connected to respective electrochemical cells of the pack, the circuit elements having electrical characteristics that are different such that individual electrochemical cells can be distinguished from one another, wherein the circuit elements comprise a first circuit element and the electrochemical cells comprise a first electrochemical cell, wherein the first circuit element is connected to a terminal of the first electrochemical cell; and

a measurement circuit configured to identify an electrochemical cell being measured, the measurement circuit being configured to perform;

a first measurement of a series combination of the first circuit element and the first electrochemical cell when a first electrical signal is applied to the series combination of the first circuit element and the first electrochemical cell; and

a second measurement of the series combination of the first circuit element and the first electrochemical cell when the first electrical signal is not applied to the series combination of the first circuit element and the first electrochemical cell.

2. The system of claim 1, wherein the circuit elements comprise resistive elements individually electrically connected to respective electrochemical cells, the resistive elements having different resistances.

3. The system of claim 2, wherein the measurement circuit is configured to make the first measurement as a measurement of a voltage across the series combination of the first circuit element and the electrochemical cell when a first current is applied to the series combination of the first circuit element and the electrochemical cell, and to make a second voltage measurement across the series combination of the first circuit element and the electrochemical cell when a second current different from the first current flows through the series combination of the first circuit element and the electrochemical cell.

4. The system of claim 3, wherein the second current is zero.

5. The system of claim 1, further comprising a current generating circuit configured to provide a current to the series combination of the first circuit element and the first electrochemical cell.

6. The system of claim 1, wherein the measurement circuit is configured to check that an electrical characteristic measured for a circuit element associated with an electrochemical cell is within an expected range of values of the electrical characteristic.

7. The system of claim 6, wherein the system is configured to use an identification of an incorrect cell or an out of range measurement to detect a fault in the measurement circuit or a balancing circuit associated with the pack.

8. The system of claim 1, wherein the electrical characteristic comprises resistance.

9. A method of measuring an electrochemical cell of a pack comprising a plurality of electrochemical cells, the method comprising:

applying a first current to a series combination of the electrochemical cell and a circuit element;

obtaining a measurement of the series combination of the electrochemical cell and the circuit element while the first current is applied;

obtaining a second measurement of the series combination of the electrochemical cell and the circuit element while a second current flows through the series combination of the electrochemical cell and the circuit element; and

determining diagnostic information related to the pack, a measurement circuit connected to the pack, and/or a balancing circuit connected to the pack based on the first and second measurements.

10. The method of claim 9, wherein the circuit element comprises a resistive element and the method comprises determining a resistance of the resistive element.

11. The method of claim 10, wherein the first measurement is a first voltage measurement across the series combination and the second measurement is a second voltage measurement across the series combination.

12. The method of claim 11, wherein the second current is zero.

13. The method of claim 9, further comprising checking that an electrical characteristic measured for a circuit element associated with an electrochemical cell is within an expected range of values of the electrical characteristic.

14. The system of claim 9, further comprising detecting a fault in a measurement circuit or a balancing circuit associated with the pack based upon an identification of an incorrect cell or an out of range measurement.

15. A measurement system for a pack of electrochemical cells, the measurement system comprising:

circuit elements individually electrically connected to respective electrochemical cells of the pack, wherein the circuit elements comprise a first circuit element and the electrochemical cells comprise a first electrochemical cell, wherein the first circuit element is connected to the first electrochemical cell; and

a measurement circuit configured to perform;

a first measurement of the voltage across a series combination of the first circuit element and the first electrochemical cell when a first current flows through the series combination of the first circuit element and the first electrochemical cell; and

a second measurement of the voltage across the series combination of the first circuit element and the first electrochemical cell when a second current flows through the series combination of the first circuit element and the first electrochemical cell, the second current being different from the first current.