Battery Pack Equalization with Periodic Wake-Up in Sleep Mode
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Solution Overview
Problem
Existing battery management systems struggle to maintain consistency among battery cells in large-capacity batteries due to limited operation time and inaccurate equalization, leading to polarization and SOC errors, and are unable to respond to abnormal faults effectively.
Innovation Solution
A method and apparatus for equalizing a battery pack that determines offline equalization conditions, identifies target cells, sets equalization time lengths, and periodically wakes up the battery management system to re-evaluate conditions, incorporating self-tests and initialization strategies to ensure accurate equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive equalization is performed based on voltage difference or SOC difference between battery cells, then consistency between battery cells is improved, but the equalization time length is limited to about 2-4 hours per day, failing to ensure consistency for large capacity batteries
Solution Approach 1:
The patent implements periodic wake-up of the main controller during sleep mode to perform equalization checks and operations. The system wakes up at predetermined intervals to detect battery cell voltages, determine equalization needs, and execute equalization commands, thereby extending the effective equalization time beyond the limited active operation periods.
Solution Approach 2:
The system performs preliminary equalization assessments during wake-up periods before entering sleep mode, pre-calculating equalization requirements and preparing equalization strategies. This allows the equalization process to be initiated or continued during subsequent sleep periods, effectively extending the equalization time length.
2Duration of action of moving object
If offline equalization is performed in sleep mode with predetermined parameters, then equalization time length is extended beyond vehicle operation time, but polarization and SOC errors lead to inaccurate equalization time calculation
Solution Approach 1:
The system continuously monitors battery cell voltages during equalization and uses this feedback to dynamically adjust equalization parameters. The main controller periodically wakes up to detect current voltage states, compares them with target values, and modifies equalization commands accordingly, correcting for polarization and SOC estimation errors through iterative feedback control.
Solution Approach 2:
The patent dynamically changes equalization parameters such as equalization current, time duration, and target voltage based on real-time battery state detection. Instead of using fixed predetermined parameters, the system adjusts parameters according to actual voltage differences, cell conditions, and state of charge estimates, improving the accuracy of equalization time calculation.
3Loss of energy
If the main controller enters sleep mode for offline equalization, then power consumption is reduced, but the battery cell collection unit lacks ability to calculate and determine system state, unable to respond to abnormal faults in time
Solution Approach 1:
The patent introduces an intermediary equalization control unit that can operate independently or semi-independently from the main controller during sleep mode. This intermediary unit handles basic equalization control tasks, fault detection, and system state monitoring, allowing the main controller to remain in low-power sleep mode while maintaining fault detection capability through the intermediary controller.
Solution Approach 2:
The main controller periodically wakes up from sleep mode to perform comprehensive system state calculations, fault assessments, and equalization strategy adjustments. During these periodic wake-up periods, the system fully evaluates battery pack status and responds to any abnormal faults detected, balancing power consumption with reliable fault detection capability.
Data Source
AI summary
A method and apparatus for equalizing a battery pack, a vehicle, and a storage medium are provided. The method includes: determining whether a current battery pack meets a predetermined offline equalization condition; determining, in response to the current battery pack meeting the predetermined offline equalization condition, a target cell to be equalized in the current battery pack, an equalization time length of the target cell, and a periodic wake-up duration; and equalizing the target cell based on the equalization time length of the target cell, controlling a battery management system to enter a sleep mode, obtaining a duration for which the battery management system is in the sleep mode, waking up the battery management system in response to the duration reaching the periodic wake-up duration, and re-determining whether the current battery pack meets the predetermined offline equalization condition.