Series Battery Cell Diagnosis Using Comparative Voltage Profiles
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Solution Overview
Problem
Existing technologies face challenges in diagnosing abnormalities in individual batteries within a series-connected battery array, as the same current flows through all batteries during charging or discharging, making it difficult to assess the status of each battery independently.
Innovation Solution
A battery diagnosing apparatus and method that utilize voltage sensors to collect voltage data from each battery in a series-connected array, generate voltage profiles representing the voltage change history of each battery, and compare these profiles to diagnose abnormalities by minimizing error with a criterion voltage profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage profiles are compared to diagnose battery abnormalities, then diagnostic accuracy is improved, but device complexity increases due to need for multiple voltage sensors and profile generation systems
Solution Approach 1:
The controller performs multiple functions: it manages battery charging/discharging operations and simultaneously generates voltage profiles for diagnostic purposes. This multi-functionality allows the existing controller to serve dual purposes without adding dedicated diagnostic hardware, thereby improving measurement precision while limiting the increase in device complexity.
Solution Approach 2:
The system creates voltage profile copies representing ideal battery behavior and compares actual voltage measurements against these profiles. By using profile comparison rather than direct physical measurement of battery health, the system achieves high diagnostic accuracy using only voltage sensor data that already exists in the system.
2Reliability
If individual battery diagnosis is implemented in series-connected battery arrays, then reliability is improved, but difficulty of detecting and measuring increases due to same current flowing through all batteries
Solution Approach 1:
Instead of attempting to measure battery state through the common current path (one dimension), the system transitions to analyzing voltage profiles over time (adding a time dimension). This dimensional shift allows individual battery diagnosis in series connections by observing how each battery's voltage behaves during charging/discharging cycles, overcoming the limitation of uniform current flow.
Solution Approach 2:
The voltage profile acts as an intermediary that translates the effect of uniform current flow into distinguishable individual battery characteristics. By comparing how each battery's voltage responds to the same current over time, the system can identify individual battery abnormalities without directly measuring current distribution or adding complex sensing infrastructure.
3Productivity
If voltage profile comparison method is used, then diagnostic speed is improved, but loss of information increases by not considering additional parameters like battery temperature
Solution Approach 1:
The system continuously monitors voltage during normal charging/discharging operations and accumulates voltage profile data over time. This continuous data collection during regular battery operation allows rapid diagnosis without requiring separate diagnostic procedures or additional measurement parameters, achieving fast diagnosis while utilizing information already available from continuous voltage monitoring.
Data Source
AI summary
A battery diagnosing apparatus, a battery pack, an electric vehicle and a battery diagnosing method are provided. The battery diagnosing apparatus is provided for a battery array including first to mth batteries (m is a natural number of 3 or more) connected in series. The battery diagnosing apparatus includes voltage sensors configured to detect voltage of each of the first to mth batteries, and a controller configured to generate first to mth voltage profiles representing a voltage change history of each of the first to mth batteries during charging or discharging of the battery array. The controller diagnoses the battery array by comparing each of first to (m−1)th comparison voltage profiles with a criterion voltage profile. The criterion voltage profile is one of the first to mth voltage profiles, and the first to (m−1)th comparison voltage profiles are remaining (m−1) voltage profiles other than the criterion voltage profile.