Parallel Battery Pack Activation with Equalization Current Compensation
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Solution Overview
Problem
Unintended charge equalization currents flowing between battery packs in parallel connection, especially in cold temperatures and high state of charge scenarios, limit battery power capabilities and lead to lithium plating and degradation.
Innovation Solution
A computer-controlled approach that activates a first battery pack and determines a compensation current to counteract expected charge equalization currents before activating additional packs, using empirical data and machine learning for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple battery packs are connected in parallel to increase power capabilities, then power capability is improved, but unintended charge equalization currents flow between packs causing lithium plating and degradation
Solution Approach 1:
The system performs preliminary assessment of battery pack states (temperature, state of charge, internal resistance) before allowing parallel connection. Compensation currents are pre-calculated and applied to counteract expected charge equalization currents before they can cause harmful effects, preventing lithium plating and degradation while enabling parallel operation for increased power capability
Solution Approach 2:
The system dynamically adjusts operational parameters including compensation current magnitude, connection timing, and activation sequences based on real-time battery pack conditions. By changing these parameters adaptively, the system enables parallel connection for power enhancement while suppressing harmful charge equalization currents that would otherwise cause degradation
2Device complexity
If a maximum current threshold is set to allow connection of multiple battery packs, then device complexity is reduced, but power capability is limited and battery utilization is reduced
Solution Approach 1:
Instead of using a fixed maximum current threshold, the system dynamically adjusts compensation current parameters based on real-time battery pack conditions including temperature, state of charge, and internal resistance. This adaptive parameter adjustment enables full utilization of multiple battery packs for maximum power capability while maintaining simple control architecture through automated parameter optimization
3Ease of operation
If battery packs are activated sequentially without compensation current, then ease of operation is improved, but charge equalization currents cause power limits to be violated
Solution Approach 1:
Before activating additional battery packs in sequence, the system pre-calculates and applies compensation currents to counteract expected charge equalization currents. This preliminary action maintains simple sequential activation procedures while ensuring power limit compliance by preventing unwanted current flows that would otherwise violate power constraints
Data Source
AI summary
A computer system controls activation of a plurality of battery packs in parallel connection. The computer system has processing circuitry to activate a first battery pack from among the plurality of battery packs; determine a compensation current which is adapted to counteract at least parts of a charge equalization current expected to be generated by a subsequent activation of an additional battery pack from among the plurality of battery packs; apply the compensation current to currently activated battery pack(s); and activate the additional battery pack.