Battery Internal Resistance Diagnosis Under Low Current Variance
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Solution Overview
Problem
Existing battery abnormality diagnosis techniques face reduced accuracy due to low variance in current values and varying charging rates, which can affect vehicle travel by increasing power consumption and lowering charging rates.
Innovation Solution
A battery abnormality diagnosis device that calculates internal resistance based on variance values and charging rate variations, executing diagnosis only when variance is sufficient and charging rate variation is within specific thresholds, ensuring accurate diagnosis without increasing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the amount of power consumed by auxiliary devices is increased to ensure variance of current values, then the calculation accuracy of internal resistance value is improved, but the charging rate of the battery is lowered
Solution Approach 1:
The patent changes the parameters used for diagnosis from relying solely on current value variance to using a composite index that includes current variance, voltage variance, and charging rate variation. This allows accurate diagnosis without increasing power consumption by auxiliary devices, as the diagnosis is performed based on existing operational data rather than forced variance through additional power consumption.
Solution Approach 2:
The patent replaces the mechanical approach of increasing power consumption to create current variance with a computational approach. Instead of physically manipulating the system to generate variance, the patent uses data processing and composite index calculation to achieve accurate diagnosis, substituting physical intervention with information processing.
2Measurement precision
If the variance of current values is increased by increasing power consumption of auxiliary devices, then the accuracy of abnormality diagnosis is improved, but the travel of the vehicle is affected
Solution Approach 1:
The patent changes the diagnostic parameters from requiring high current variance to using a composite index that can be calculated from normal operational data. The composite index incorporates current variance, voltage variance, and charging rate variation, allowing accurate diagnosis during normal vehicle operation without affecting travel productivity.
Solution Approach 2:
The patent enables the battery system to perform self-diagnosis using its own operational data without requiring external intervention or additional power consumption. The composite index is calculated from data already generated during normal battery operation, allowing the system to diagnose itself without impacting vehicle travel.
3Measurement precision
If the variation amount of charging rate is large during data acquisition, then the calculation accuracy of internal resistance value is lowered, but the diagnosis can still be performed with composite index
Solution Approach 1:
The patent transitions from a single parameter approach (current variance) to a multi-parameter composite index that includes current variance, voltage variance, and charging rate variation. This composite index remains effective even when charging rate varies, as it captures the overall operational characteristics rather than relying on stable charging conditions.
Solution Approach 2:
The patent creates a dynamic diagnostic system that adapts to varying charging conditions. Instead of requiring stable charging rates, the composite index dynamically adjusts to capture battery characteristics under different operational conditions, making the diagnosis versatile and applicable in real-world varying conditions.
Data Source
AI summary
A battery abnormality diagnosis device, comprising: an acquisition unit that acquires multiple current values and multiple voltage values within a predetermined period of a battery; a calculation unit that calculates an internal resistance value of the battery based on a dispersion value of the current values, a variation amount of the charging rate of the battery, and the current values and the voltage values, within the predetermined period; and a diagnosis unit that executes abnormality diagnosis processing based on the internal resistance value, wherein the diagnosis unit executes the abnormality diagnosis processing based on the internal resistance value calculated when the dispersion value is equal to or more than a predetermined value and the variation amount is equal to or less than a first threshold, or when the dispersion value is less than the predetermined value and the variation amount is equal to or less than a second threshold.