Method and apparatus for battery cell charge balancing

Patent metadata

Field	Value
Publication number	US-11211803-B2
Application number	US-201916589586-A
Country	US
Kind code	B2
Filing date	Oct 1, 2019
Priority date	Oct 1, 2019
Publication date	Dec 28, 2021
Grant date	Dec 28, 2021

Abstract

A system and associated method are described for balancing an electrical parameter associated with stored electric power in a multi-cell battery. A cell charge balancing system determines a first plurality of the electrical parameters associated with respective ones of the plurality of cells, a plurality of first charge parameters associated with the cells, and a first quality index. A second plurality of the electrical parameters are determined, and second charge parameters are determined to determine a second quality index. The first and second quality indices are compared, and a cell charge balancing routine controls the balancing system based upon the first quality index when the first quality index is greater than the second quality index. The cell charge balancing routine controls the cell charge balancing system based upon the second quality index when the first quality index is less than the second quality index.

First claim

What is claimed is:

1. A system comprising:
a battery including a plurality of cells;
a plurality of sensors coupled to the plurality of cells, wherein the plurality of sensors are arranged to determine electrical parameters associated with the plurality of cells;
a cell charge balancing system coupled to the plurality of cells, wherein the cell charge balancing system is arranged to control an amount of energy stored in each of the plurality of cells; and
a battery controller in communication with the plurality of sensors and the cell charge balancing system, the battery controller including an instruction set, the instruction set executable to:
determine, at a first timepoint, a first plurality of the electrical parameters associated with respective ones of the plurality of cells,
determine a plurality of first charge parameters associated with the plurality of cells based upon the respective first plurality of electrical parameters,
determine a first quality index based upon the plurality of first charge parameters,
determine, at a second timepoint subsequent to the first timepoint, a second plurality of the electrical parameters associated with respective ones of the plurality of cells,
determine a plurality of second charge parameters associated with the plurality of cells based upon the respective second plurality of electrical parameters,
determine a second quality index based upon the plurality of second charge parameters,
compare the first and second quality indices,
execute a cell charge balancing routine to control the cell charge balancing system based upon the first quality index when the first quality index is greater than the second quality index, and
execute the cell charge balancing routine to control the cell charge balancing system based upon the second quality index when the first quality index is less than the second quality index; wherein the instruction set executable to determine the first quality index based upon the plurality of first charge parameters comprises the instruction set executable to determine a first open circuit time quality index associated with the first plurality of the electrical parameters during a first rested state, a first low current quality index associated with the first plurality of the electrical parameters during the low current state, and a first charge complete event quality index associated with the first plurality of the electrical parameters at the charge complete event; and select a first maximum of the first open circuit time quality index, the first low current quality index, and the first charge complete event quality index as the first quality index.

2. The system of claim 1 , wherein the instruction set executable to determine, at the first timepoint, the first plurality of the electrical parameters associated with the respective ones of the plurality of cells comprises the instruction set executable to determine the first plurality of the electrical parameters during one of a rested state, a low current state, or at a charge complete condition at the first timepoint.

3. The system of claim 1 , wherein the instruction set executable to determine, at the second timepoint subsequent to the first timepoint, the second plurality of the electric parameters associated with the respective ones of the plurality of cells comprises the instruction set executable to determine the second plurality of the electrical parameters during one of a rested state, a low current state, or at a charge complete condition at the second timepoint.

4. The system of claim 1 , wherein the instruction set executable to determine the second quality index based upon the plurality of second charge parameters comprises the instruction set executable to determine an open circuit time quality index associated with the second plurality of the electrical parameters during a rested state, a low current quality index associated with the second plurality of the electrical parameters during the low current state, and a charge complete event quality index associated with the second plurality of the electrical parameters at the charge complete event; and select a maximum of the open circuit time quality index, the low current quality index, and the charge complete event quality index as the second quality index.

5. The system of claim 1 , wherein the instruction set executable to compare the first and second quality indices further comprises the instruction set executable to subject the first quality index subject to a decay parameter based upon a difference between the first and second timepoints.

6. The system of claim 1 , wherein the instruction set executable to execute the cell charge balancing routine to control the balancing system comprises the instruction set executable to selectively charge individual ones of the cells, discharge individual ones of the cells, and redistribute energy between individual ones of the cells to achieve equivalent charge balance points in all of the cells.

7. The system of claim 6 , wherein the equivalent charge balance points comprise a state of charge.

8. The system of claim 6 , wherein the equivalent charge balance points comprise a voltage level.

9. A method for charge balancing a multi-cell battery, comprising:
determining, at a first timepoint, a first plurality of electrical parameters associated with respective ones of a plurality of cells of the multi-cell battery;
determining a plurality of first charge parameters associated with the plurality of cells based upon the first plurality of electrical parameters;
determining a first quality index based upon the plurality of first charge parameters;
determining, at a second timepoint subsequent to the first timepoint, a respective second plurality of the electrical parameters associated with the respective ones of the plurality of cells of the multi-cell battery;
determining a plurality of second charge parameters associated with the plurality of cells based upon the respective second plurality of electrical parameters;
determining a second quality index based upon the plurality of second charge parameters;
comparing the first and second quality indices;
executing a cell charge balancing routine to control a balancing system based upon the first quality index when the first quality index is greater than the second quality index; and
executing a cell charge balancing routine to control the balancing system based upon the second quality index when the first quality index is less than the second quality index;
determining the first quality index based upon the plurality of first charge parameters comprises determining a first open circuit time quality index associated with the first plurality of the electrical parameters during a first rested state, a first low current quality index associated with the first plurality of the electrical parameters during a first low current state, and a first charge complete event quality index associated with the first plurality of the electrical parameters at a first charge complete event; and selecting a first maximum of the first open circuit time quality index, the first low current quality index, and the first charge complete event quality index as the first quality index; and
determining the second quality index based upon the plurality of second charge parameters comprises determining a second open circuit time quality index associated with the second plurality of the electrical parameters during a second rested state, a second low current quality index associated with the second plurality of the electrical parameters during a second low current state, and a second charge complete event quality index associated with the second plurality of the electrical parameters at a seco

Assignees

• Gm Global Tech Operations Llc

Inventors

• Bunnell Justin
• Seeman Garrett M
• Cho Joseph

Classifications

• H02J7/56

  Active balancing, e.g. using capacitor-based, inductor-based or DC-DC converters · CPC title

• H02J7/54 Primary

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

• H02J7/933

  the cycle being controlled or terminated in response to electric parameters · CPC title

• H02J7/82

  Control of state of charge [SOC] · CPC title

• H02J7/52 Primary

  for charge balancing, e.g. equalisation of charge between batteries · CPC title