Battery Management System Dynamic OCV Reset for SOC Accuracy
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Solution Overview
Problem
Existing battery management systems struggle to accurately reset the state of charge (SOC) of electric and hybrid vehicle batteries due to a fixed waiting time for open circuit voltage (OCV) stabilization, which can lead to incomplete SOC calculation if charge and discharge occur before the waiting period ends.
Innovation Solution
A battery management system that dynamically resets OCV based on battery temperature, using a data table to set an OCV idle period and compares this period with the actual battery idle time to determine when to reset the SOC, ensuring accurate SOC estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed waiting time is used for OCV stabilization, then the system structure is simple, but the SOC reset accuracy deteriorates when charge/discharge occurs during the waiting period
Solution Approach 1:
The patent applies dynamics by making the waiting time for OCV measurement variable rather than fixed. The control unit dynamically adjusts the waiting time based on real-time detection of charge/discharge current status. When no current flows, the system waits for the temperature-dependent idle period; when current flows, the system extends the waiting time until current cessation, thereby adapting the measurement process to actual battery conditions and improving SOC reset accuracy.
Solution Approach 2:
The patent implements feedback by continuously monitoring the battery's charge/discharge current status during the OCV measurement process. The control unit detects whether current is flowing and uses this feedback information to determine whether to extend the waiting period. This closed-loop feedback mechanism ensures that OCV is only measured when the battery is truly at rest, eliminating the trade-off between fixed simple timing and accurate variable timing.
2Measurement precision
If the waiting time for OCV reset is extended, then the SOC reset accuracy improves, but the time loss increases
Solution Approach 1:
The patent applies parameter changes by making the waiting time parameter variable based on battery temperature and actual current status. Instead of using a universally extended waiting time, the system determines the appropriate idle period according to the detected battery temperature from pre-stored temperature-time correspondence data. This approach minimizes waiting time to the essential minimum required for accurate measurement, reducing time loss while maintaining SOC reset accuracy.
3Productivity
If the OCV measurement is performed immediately without waiting, then the time loss is reduced, but the SOC calculation accuracy deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-storing the correspondence data between battery temperature and required idle periods before actual operation. During SOC reset, the control unit simply queries this pre-prepared data based on the current temperature to determine the appropriate waiting time, rather than performing complex real-time calculations or experiments. This preliminary preparation enables rapid determination of the minimum necessary waiting time, achieving both fast SOC reset speed and high accuracy.
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 allows for more accurate and timely SOC resetting, reducing errors and improving the reliability of SOC estimation in varying battery conditions.
Implementation Method 1
An electric vehicle refers to a vehicle using a battery engine that operates on electrical energy output from a battery
Implementation Method 2
When the battery has not been charged and discharged for a predetermined time, the OCV is reset once the chemical reaction in the battery is stabilized and the voltage does not change
Data Source
AI summary
A battery management system and a method of operating the same includes a plurality of battery cells constituting one pack and connected to a battery having at least one pack, and determines an estimated state of charge (SOC) of the battery. The battery management system determines whether or not a pack current flows, and controls a reset of an SOC depending on the determination result. The battery management system sets an OCV idle period associated with a temperature of the battery, and compares the idle period with a time for which the current of the battery does not flow, and sets the reset OCV depending on the comparison result. The battery management system resets the estimated SOC as the reset SOC associated with the reset OCV.