Dynamic Battery Rebalancing for EV Cell Homogeneity

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Solution Overview

Problem

Battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs) face inefficiencies and reduced battery durability due to unequal states of charge among battery cells, which can be exacerbated by incremental rebalancing methods that are time-consuming and inefficient.

Innovation Solution

Implementing a system with controllers that determine whether to rebalance the battery in a single cycle or multiple cycles based on driver input and available time, using techniques such as voltage measurement, self-discharge rate analysis, and vehicle run time thresholds to identify imbalances and optimize rebalancing strategies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If incremental rebalancing is used to maintain battery cell charge equality, then battery durability is improved, but rebalancing efficiency deteriorates and time consumption increases

Engineering Contradiction:

Improvebattery durabilityVSAvoidrebalancing efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system dynamically adjusts the rebalancing strategy between incremental and single-cycle approaches based on real-time conditions such as driver input and available time, allowing the rebalancing process to adapt its pace and intensity to optimize both durability and efficiency

Inventive Principle:

Principle #15Dynamics

2Stability of the object's composition

If incremental rebalancing is used to correct charge imbalances, then cell state equality is improved, but time consumption increases

Engineering Contradiction:

Improvecell state equalityVSAvoidrebalancing time

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

The system dynamically selects between incremental and single-cycle rebalancing modes based on available time and driver preferences, allowing flexible adjustment of the rebalancing timeline while maintaining cell state equality

Inventive Principle:

Principle #15Dynamics

3Productivity

If single cycle rebalancing is used to improve efficiency, then rebalancing time is reduced, but risk of over-charging increases

Engineering Contradiction:

Improverebalancing efficiencyVSAvoidover-charging risk

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system continuously monitors cell voltage and charge state during rebalancing, using feedback signals to adjust charging rates and terminate cycles appropriately, preventing over-charging while maintaining efficiency

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system changes charging parameters such as charge rate and voltage thresholds based on real-time cell state measurements, allowing safe single-cycle rebalancing by dynamically adjusting operational parameters

Inventive Principle:

Principle #35Parameter changes

4Speed

If high-rate charging is used in single cycle rebalancing, then charging speed is improved, but cell over-charging risk increases

Engineering Contradiction:

Improvecharging speedVSAvoidover-charging harm

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8030894B2System and method for rebalancing a vehicle battery

Publication Date: 2011.10.04 FORD GLOBAL TECH LLC

AI summary

A vehicle may include an electric machine, a battery, a driver interface and one or more controllers. The one or more controllers may be configured to determine whether a battery imbalance condition exists, to cause an alert to be generated via the driver interface if a battery imbalance condition exists, to determine whether a response to the alert is received, and to cause the battery to be rebalanced in a single cycle if a response to the alert is received.