# US 2014/0197682 A1 · Autonomous charge balancing circuit and method for battery pack

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- Number: US 2014/0197682 A1
- Document ID: US20140197682A1
- Status: Published application
- Kind: A1
- Application number: 13/742,437
- Filed: 2013-01-16
- Published: 2014-07-17
- Earliest claimed: 2013-01-16
- Assignees: Ford Global Technologies, LLC
- Applicants: Ford Global Technologies, LLC
- Inventors: Benjamin A. Tabatowski-Bush; Tuyen Quoc Tran
- Web page: https://patentgrep.com/patent/US20140197682A1

## CPC

- B60L 58/10: for monitoring or controlling batteries
- B60L 58/22: Balancing the charge of battery modules
- H02J 7/54: Passive balancing, e.g. using resistors or parallel MOSFETs
- B60L 50/16: with provision for separate direct mechanical propulsion
- B60R 16/0315: {using multiplexing techniques (multiplexing for transmission of signals G08C15/00; multiplexing for electrical communication in general H04J)}
- H02J 2105/37: exchanging power with electric vehicles [EV] or with hybrid electric vehicles [HEV]
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- B60R: VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Systems and methods for controlling a vehicle having a traction battery with a plurality of cell groups each having a plurality of serially connected battery cells include balancing each cell of each cell group with a corresponding autonomous cell balancing circuit, and coupling a single output associated with each cell group to an associated battery monitoring circuit. An integrated driver and switch circuit adapts the voltage from an associated cell group for powering battery monitoring integrated circuits with a voltage range corresponding to a single cell voltage range to facilitate use of an existing battery monitoring integrated circuit design and subsequent input to a microprocessor-based battery controller. Cell balancing is performed at each cell with a battery monitor circuit associated with each group of cells.

## Claims

### Claim 1

A method for controlling a traction battery for a vehicle having a plurality of cell groups each having a plurality of serially connected battery cells, comprising:
balancing each cell of each cell group with a corresponding autonomous cell balancing circuit; and
coupling a single output associated with each cell group to an associated battery monitoring circuit.

### Claim 2 (depends on 1)

The method as described in claim 1, comprising:
coupling a plurality of cell groups in series to form a stack; and
coupling a single output signal from each stack to a battery controller.

### Claim 3 (depends on 2)

The method as described in claim 2, wherein the battery controller comprises a microprocessor.

### Claim 4 (depends on 1)

The method as described in claim 1 further comprising:
coupling a voltage divider circuit to each cell group, wherein the single output coupled to the associated battery monitoring circuit comprises an output from the voltage divider circuit.

### Claim 5 (depends on 4)

The method as described in claim 4 wherein each cell balancing circuit and an associated voltage divider circuit are formed on a single substrate.

### Claim 6

A control system for a vehicle having a traction battery with a plurality of cell groups, each cell group having a corresponding plurality of cells coupled in series, comprising:
a plurality of cell balancing circuits, each electrically connected across one of the plurality of cells; and
a plurality of battery monitor circuits, each connected to a single output from at least one of the plurality of cell groups.

### Claim 7 (depends on 6)

The system as described in claim 6 wherein each cell balancing circuit comprises an autonomous analog cell balancing circuit.

### Claim 8 (depends on 6)

The system as described in claim 6, further comprising:
an interface circuit having inputs connected across an associated cell group and an output connected to a corresponding one of the plurality of battery monitor circuits, the output supplying a voltage to the corresponding battery monitor circuit in a voltage range corresponding to a voltage range of an individual one of the plurality of cells.

### Claim 9 (depends on 8)

The system as described in claim 8, wherein each of the plurality of cell balancing circuits comprises:
a closed-loop feedback controller configured to control shunt current across an associated cell in response to a difference between measured cell voltage and a reference cell voltage.

### Claim 10 (depends on 9)

The system of claim 9 wherein each of the plurality of cell balancing circuits further comprises a temperature sensor coupled to the closed-loop feedback controller and wherein the closed-loop feedback controller controls the shunt current in response to temperature of the cell.

### Claim 11 (depends on 9)

The system of claim 9 wherein the closed-loop feedback controller is implemented by an integrated circuit having a common substrate with an associated battery monitor circuit.

### Claim 12 (depends on 6)

The system of claim 6 further comprising:
a microprocessor-based battery controller coupled to each of the plurality of battery monitor circuits.

### Claim 13 (depends on 6)

The system of claim 6 wherein each of the plurality of battery monitor circuits includes multiple channels and wherein each of the multiple channels is connected to one of the plurality of cell groups.

### Claim 14 (depends on 6)

The system of claim 6 wherein the plurality of cell groups is connected in series, the system further comprising a microprocessor-based battery controller connected to the plurality of cell groups.

### Claim 15

A system for controlling a vehicle, comprising:
a traction battery having a plurality of cell groups each having an associated plurality of cells connected in series;
a cell balancing circuit connected across each cell, each cell balancing circuit configured to control shunt current across an associated cell in response to a difference between a reference cell voltage and a measured cell voltage;
an interface circuit having inputs connected across an associated one of the plurality of cell groups and providing an output voltage in a range corresponding to a voltage range of a single one of the plurality of cells;
a battery monitor circuit coupled to each interface circuit; and
a battery controller coupled to the battery monitor circuit.

### Claim 16 (depends on 15)

The system of claim 15 wherein the cell balancing circuit comprises a temperature sensor and wherein the shunt current is controlled in response to a signal from the temperature sensor.

### Claim 17 (depends on 15)

The system of claim 15 wherein the cell balancing circuit and the interface circuit are formed on a common integrated circuit substrate.

### Claim 18 (depends on 15)

The system of claim 15 wherein the cell balancing circuit comprises an analog feedback controller that controls shunt current in response to cell temperature.

### Claim 19 (depends on 15)

The system of claim 15 wherein the battery comprises a lithium-ion battery

### Claim 20 (depends on 15)

The system of claim 15 wherein the interface circuit comprises a voltage divider circuit.