Mixed-Chemistry Battery Pack Power Split for Longer Cycle Life
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Solution Overview
Problem
Rechargeable energy storage systems (RESSs) experience degradation, efficiency decreases, and capacity loss due to repetitive charging and discharging, particularly in mixed chemistry battery packs used for vehicle traction motors, which are not effectively managed by existing technologies.
Innovation Solution
A method and system for managing the cycle life of mixed chemistry battery packs by independently controlling the charging and discharging of subpacks with different configurations, using a DC-DC converter to regulate power flow and a controller to optimize power distribution, prioritizing the use of a propulsion subpack over an energy subpack to extend cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the battery pack operates at high power levels to meet driving demands, then the power delivery performance is improved, but the cycle life and capacity degradation worsen due to repetitive severe charging and discharging
Solution Approach 1:
The battery pack is divided into multiple subpacks with different chemistries (e.g., LFP and NMC) that are independently managed. Each subpack can be controlled to operate in different modes, allowing the system to distribute power demands across subpacks based on their individual characteristics and state of charge, thereby reducing stress on any single subpack and extending overall cycle life while maintaining high power delivery capability.
2Ease of manufacture
If the battery pack uses a single chemistry composition, then the manufacturing and control simplicity is improved, but the ability to optimize for both high power and long duration performance worsens
Solution Approach 1:
The mixed chemistry battery pack creates a universal system that can adapt to different operating conditions by selectively utilizing different subpacks. The control system can dynamically allocate power between subpacks based on driving conditions, state of charge levels, and performance requirements, providing both high power bursts and sustained energy delivery from a single integrated pack design.
3Speed
If the battery management system prioritizes meeting immediate power demands, then the responsiveness to driving load is improved, but the long-term capacity retention and efficiency worsen due to excessive stress on battery components
Solution Approach 1:
The battery management system performs preliminary assessments of subpack states (charge levels, temperature, health status) before allocating power demands. By proactively managing state of charge thresholds and predicting subpack availability, the system can prepare optimal power distribution strategies in advance, ensuring immediate responsiveness to driving demands while preventing excessive stress that would lead to capacity loss.
Solution Approach 2:
The system continuously monitors the state of charge, temperature, and performance metrics of each subpack, using this feedback to dynamically adjust power allocation. When subpacks approach critical thresholds or show signs of degradation, the control system automatically redistributes loads to preserve capacity and extend life, while maintaining the ability to respond quickly to driving conditions through real-time adjustments.
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
Enhances the cycle life of mixed chemistry battery packs by minimizing degradation and maintaining performance through optimized power management, thereby prolonging the operational lifespan and efficiency of the battery system.
Implementation Method 1
using a DC-DC converter to regulate power flow
Data Source
AI summary
A method for cycle life management of a mixed chemistry battery pack configured for electrically powering a traction motor of a vehicle. The method may include determining a driving load request made for requesting the mixed chemistry battery pack to provide a requested amount of electrical power to the traction motor for purposes of driving the vehicle and disconnecting the driving load request into a battery request suitable for providing the requested amount of electrical power from the mixed chemistry battery pack while managing a cycle life of the mixed chemistry battery pack independently of the driving load request.