Battery Charge Equalization During Inactive EV Modes

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Solution Overview

Problem

Existing accumulator battery management systems for electric vehicles incur discharging of the low-voltage battery during inactive modes, reducing autonomy and efficiency.

Innovation Solution

A system where the management of accumulator battery charge equalization is handled solely by slave controllers during inactive mode, without relying on the master controller powered by the low-voltage battery, thereby preventing discharging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the master controller determines charge equalizing terms during inactive mode, then charge equalization is maintained, but the low-voltage battery autonomy is reduced due to discharging

Engineering Contradiction:

Improvecharge equalizationVSAvoidlow-voltage battery autonomy

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Slave controllers autonomously determine charge equalizing terms for their respective accumulator nodes during inactive mode without requiring master controller intervention. Each slave controller independently monitors its node's accumulator charges and calculates equalization terms, enabling the system to self-manage charge equalization while the master controller remains dormant and conserving low-voltage battery power.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The charge equalization function is segmented from the master controller and distributed to individual slave controllers. Each slave controller is responsible for determining equalization terms for its specific accumulator node, dividing the centralized control function into distributed autonomous units that operate independently during inactive mode.

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If the master controller operates during inactive mode to maintain charge equalization, then accumulation charge balance is preserved, but system efficiency decreases due to continuous power consumption

Engineering Contradiction:

Improveaccumulation charge balanceVSAvoidsystem efficiency

Core Design Contradiction:

Stability of the object's compositionVSProductivity

Solution Approach 1:

Charge equalization determination is performed periodically rather than continuously. Slave controllers activate to determine equalization terms at scheduled intervals during inactive mode, then return to sleep mode. This periodic operation maintains accumulator charge balance while minimizing power consumption by keeping controllers dormant between measurement cycles.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

Slave controllers autonomously perform charge equalization determination without requiring master controller operation. During inactive mode, slave controllers independently monitor their accumulator nodes and calculate equalization terms when activated, eliminating the need for continuous master controller operation and improving overall system efficiency.

Inventive Principle:

Principle #25Self-service

3Use of energy by moving object

If slave controllers autonomously determine equalizing terms during inactive mode, then low-voltage battery autonomy is preserved, but control precision may be reduced

Engineering Contradiction:

Improvelow-voltage battery autonomyVSAvoidcharge equalization accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

Slave controllers continuously monitor accumulator charge states and use feedback from these measurements to adjust equalization terms. The autonomous determination process incorporates real-time charge level data from each accumulator, allowing slave controllers to precisely calculate equalization requirements based on actual measured conditions rather than estimated parameters.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces wireless communication between master and slave controllers with direct electrical connections for charge equalization control. Slave controllers are electrically connected to their respective accumulator nodes, enabling precise measurement and control without the signal loss or interference that could occur through wireless transmission, thereby maintaining high measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS20250042298A1Battery management system and method for equalizing the charges of the accumulator cells of the battery

Publication Date: 2025.02.06 NISSAN MOTOR CO LTD

AI summary

This management system (1) for managing a battery of accumulator cells (2) of an electric vehicle comprises a plurality of secondary controllers (7) coupled respectively to a plurality of accumulator cells (10) of the battery (2) and a primary controller (6) configured to determine the terms for equalizing the charge of the accumulator cells (10) when the management system (1) is in an active mode, the management system (1) comprising an inactive mode in which the terms by which the charges are equalized are determined only by the secondary controllers (7).