Early Discharge Voltage Monitoring for Cell Deterioration Detection

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Solution Overview

Problem

Existing methods for detecting lithium-ion secondary cell deterioration, such as those using the dV/dQ ratio, require multiple feature points and are time-consuming.

Innovation Solution

A control apparatus and method that utilize voltage information from the early stage of discharge to quickly determine the presence or absence of cell deterioration by monitoring voltage changes during discharge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the dV/dQ ratio method is used to detect cell deterioration, then measurement precision is improved, but loss of time increases due to requiring multiple feature points

Engineering Contradiction:

Improvedeterioration detection accuracyVSAvoidstate assessment time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by using voltage information from the early stage of discharge (before the cell reaches full discharge) to determine deterioration. Instead of waiting to collect multiple feature points throughout the entire discharge cycle, the method performs the deterioration assessment using only early-stage voltage data, thus saving time while maintaining detection capability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses partial action by collecting only a portion of the voltage information needed for traditional dV/dQ analysis - specifically, only the early stage discharge voltage data is used rather than requiring multiple feature points from the entire discharge cycle. This partial data set is sufficient for deterioration detection, reducing the time investment while achieving the measurement objective

Inventive Principle:

Principle #16Partial or excessive action

2Reliability

If multiple feature points are collected for dV/dQ analysis, then reliability of deterioration detection is improved, but productivity decreases due to extended detection time

Engineering Contradiction:

Improvedeterioration detection reliabilityVSAvoidstate assessment speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The determination is made in advance during the early stage of discharge rather than waiting until multiple feature points are collected. The control apparatus uses the voltage information available at this earlier time point to perform the deterioration determination, improving productivity without sacrificing reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent extracts only the essential voltage information needed for deterioration detection - specifically the voltage data from the early discharge stage - and uses this extracted information to determine cell state. This extraction approach maintains detection reliability while eliminating the need to collect and process additional feature points, thus improving productivity

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS9575137B2Control apparatus, control method, power supply system, and electric-powered vehicle

Publication Date: 2017.02.21 MURATA MFG CO LTD

AI summary

A control apparatus includes, for example, an input unit to which a plurality of pieces of voltage information related to a voltage of an electric storage unit upon discharge are input, and a determination unit configured to use the voltage information in an early stage of the discharge and determine the presence or absence of a deterioration of the electric storage unit.