Electrochemical cell monitoring and balancing circuit with self-diagnostic feature

• US 10,416,238 B2
• Filed: 03/26/2015
• Issued: 09/17/2019
• Est. Priority Date: 12/06/2010
• Status: Active Grant

• Current Assignee: Exergonix, Inc.
• Original Assignee: Exergonix, Inc.
• Inventors: Nortman, Peter Fredrick, Sufrin-Disler, Daniel A., Weicker, Phillip John, Mcgulpin, Patrick J.
• Primary Examiner(s): Zhou, Zixuan
• Application Number:
  US14/669,286
• Publication Number:
  US 20150198671A1
• Time in Patent Office: 1,636 Days
• Field of Search: 320116-119
• 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 method of monitoring an electrochemical cell, the method comprising:

measuring a voltage reading of the electrochemical cell;

measuring a change in voltage of the electrochemical cell over a time period, wherein the electrochemical cell is operably connected to balancing circuitry configured to charge or discharge the electrochemical cell, and wherein the change in voltage of the electrochemical cell over the time period is measured as the electrochemical cell charges or discharges;

determining, based at least partially on the change in the voltage of the electrochemical cell over the time period, a state of charge of the electrochemical cell;

determining, using the state of charge of the electrochemical cell, whether the voltage reading accurately represents a voltage of the electrochemical cell; and

diagnosing a fault of the balancing circuitry based on the determination whether the voltage reading accurately represents the voltage of the electrochemical cell.

2. The method of claim 1, wherein, when the change in the voltage of the electrochemical cell over the time period is higher than a threshold, the state of charge of the electrochemical cell is determined to correspond to a low state of charge or a high state of charge.

3. The method of claim 2, wherein, when the change in the voltage of the electrochemical cell over the time period is lower than a threshold, the state of charge of the electrochemical cell is determined to correspond to a moderate state of charge between the low state of charge and the high state of charge.

4. The method of claim 2 further comprising identifying which of two or more possible voltage readings for the electrochemical cell is correct based upon the determined state of charge of the electrochemical cell.

5. The method of claim 4, wherein the two or more possible voltage readings are produced as a result of the fault of the balancing circuitry.

6. A system for monitoring an electrochemical cell, the system comprising:

a balancing circuit configured to charge or discharge the electrochemical cell;

a measurement circuit configured to;

determine measure a voltage reading of the electrochemical cell; and

measure a change in voltage of the electrochemical cell over a time period, wherein the change in voltage of the electrochemical cell over the time period is measured as the electrochemical cell charges or discharges; and

a controller configured to;

determine, based at least partially on the change in the voltage of the electrochemical cell over the time period, a state of charge of the electrochemical cell;

determine, using the state of charge of the electrochemical cell, whether the voltage reading accurately represents a voltage of the electrochemical cell; and

diagnose a fault of the balancing circuit based on the determination whether the voltage reading accurately represents the voltage of the electrochemical cell.

7. The system of claim 6, wherein, when the change in the voltage of the electrochemical cell over the time period is higher than a threshold, the state of charge of the electrochemical cell is determined to correspond to a low state of charge or a high state of charge.

8. The system of claim 7, wherein, when the change in the voltage of the electrochemical cell over the time period is lower than a threshold, the state of charge of the electrochemical cell is determined to correspond to a moderate state of charge between the low state of charge and the high state of charge.

9. The system of claim 7, wherein one of two or more possible voltage readings for the electrochemical cell is identified to be correct based upon the determined state of charge of the electrochemical cell.

10. The system of claim 9, wherein the two or more possible voltage readings are produced as a result of the fault of the balancing circuit.

11. A method of monitoring an electrochemical cell, the method comprising:

measuring a first voltage reading of the electrochemical cell;

measuring a change in voltage of the electrochemical cell over a time period as the electrochemical cell charges or discharges;

determining, based at least partially on the change in the voltage of the electrochemical cell over the time period, a state of charge of the electrochemical cell; and

determining, using the state of charge of the electrochemical cell, whether the voltage reading accurately represents a voltage of the electrochemical cell, and

diagnosing a fault of balancing circuitry operably connected to the electrochemical cell based on the determination whether the voltage reading accurately represents the voltage of the electrochemical cell, the fault of the balancing circuitry being one of the balancing circuitry is stuck on and the balancing circuitry is stuck off.

12. The method of claim 11, wherein, when the change in the voltage of the electrochemical cell over the time period is higher than a threshold, the state of charge of the electrochemical cell is determined to correspond to a low state of charge or a high state of charge.

13. The method of claim 12, wherein, when the change in the voltage of the electrochemical cell over the time period is lower than a threshold, the state of charge of the electrochemical cell is determined to correspond to a moderate state of charge between the low state of charge and the high state of charge.