Battery Voltage Monitoring for Early Thermal Runaway Warning
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Solution Overview
Problem
Existing battery monitoring systems, particularly for high-voltage batteries, face challenges in efficiently detecting thermal runaway due to the limitations of pressure sensors on the main board and temporal offsets in CO2 detection, which complicate data verification and increase the risk of delayed overheating warnings.
Innovation Solution
A method involving regular measurement periods to determine cell and pack voltages using a microprocessor, triggering an overheating warning if voltage drops by defined error values, with adaptable measurement frequencies based on charging, operating, and idle modes, and incorporating temperature and CO2 sensors for immediate thermal event identification without relying on additional detection apparatuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure sensor is arranged on the main board to detect thermal events, then thermal runaway detection capability is improved, but the main board has to be physically enlarged and data verification according to ASIL standard becomes more difficult
Solution Approach 1:
The pressure sensor is extracted from the main board and relocated to the cell pack level, where it directly monitors the specific cell pack for which it is responsible. This eliminates the need to enlarge the main board while maintaining thermal runaway detection capability at the source of potential issues.
Solution Approach 2:
The battery monitoring system is segmented into independent cell pack-level units, each with its own pressure sensor. This distributed architecture allows each cell pack to be monitored independently without requiring a centralized sensor on the main board, simplifying both the main board design and verification processes.
2Reliability
If CO2 emission is detected to monitor thermal runaway, then thermal event monitoring is achieved, but there is a temporal offset between cell heating and CO2 identification
Solution Approach 1:
The pressure sensor detects pressure changes that occur earlier in the thermal runaway process, before CO2 emission becomes detectable. By monitoring pressure as a preliminary indicator, the system identifies thermal events sooner, allowing for earlier warning and intervention before the temporal offset of CO2 detection becomes an issue.
3Speed
If measurement frequency is increased to detect thermal runaway faster, then detection speed is improved, but energy consumption increases
Solution Approach 1:
The measurement frequency is made dynamic rather than static. The system adapts the measurement interval based on the current operational state of the battery pack, performing frequent measurements when risk is higher and less frequent measurements when risk is lower. This optimizes the balance between detection speed and energy consumption.
Solution Approach 2:
The measurement parameters are changed based on operational context. Different measurement frequencies are applied depending on whether the battery is charging, discharging, or in idle state, allowing the system to maintain high detection capability when needed while conserving energy during low-risk periods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables faster and more accurate detection of thermal runaway, reducing the risk of overheating by triggering warnings earlier and adapting measurement frequencies to different battery states, thereby ensuring safer battery operation.
Implementation Method 1
determining a cell voltage of at least one battery cell, determining an associated cell pack voltage of the at least one battery cell and evaluating the cell voltage and the cell pack voltage
Implementation Method 2
detect CO2 being emitted, which, as a result of a cell being excessively heated, escapes from the electrolyte of the cell
Data Source
AI summary
The present invention relates to a method for operating a battery, which includesdetermining the cell voltage of at least one battery cell,determining the associated cell pack voltage of the at least one battery cell, andevaluating the cell voltage and the cell pack voltage by means of an analysis program on a microprocessor in a main control unit, where an overheating warning message is triggered if, within a defined measurement period, the cell voltage decreases by a defined cell error value and the cell pack voltage decreases by a defined pack error value.