Battery Module Balancing via Magnetic Energy Transfer
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Solution Overview
Problem
Battery management systems face challenges in balancing voltages and states of charge across multiple battery cells in a pack, leading to inefficiencies and reduced lifespan due to uneven degradation and charging/discharging imbalances.
Innovation Solution
A method involving a detection and control unit that calculates average cell parameters, identifies donor and receiver modules, and transfers energy between them using a magnetic device with windings and switches to balance voltages and states of charge during charging and discharging processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the battery management system continues to charge the whole battery pack when the lowest charge cell is not yet fully charged, then the charging process can be completed faster, but another battery cell having a higher charge may be over-charged
Solution Approach 1:
The battery pack is segmented into multiple battery modules, each with its own detection and control unit. This allows independent monitoring and control of each module's charging state, enabling the system to identify and balance individual cells without halting the entire charging process, thus maintaining charging speed while preventing overcharge
Solution Approach 2:
The detection and control units continuously monitor cell voltages and provide feedback to the central control unit. This real-time feedback mechanism enables dynamic adjustment of charging currents to individual modules, ensuring that cells with higher charge receive less current while preventing overcharge, thereby resolving the contradiction between charging speed and charge balance
2Productivity
If the battery management system controls the whole battery pack to provide power continuously when the highest charge cell is not fully discharged, then the power supply can be maintained without interruption, but another battery cell having a lower charge may be over-discharged
Solution Approach 1:
The battery pack is divided into independent battery modules with separate detection and control units. This segmentation allows the system to manage discharge operations at the module level, identifying cells with lower charge and adjusting their discharge contribution, thereby maintaining overall power supply continuity while preventing individual cell over-discharge
Solution Approach 2:
During discharge, detection units continuously monitor cell voltages and provide feedback to control units. The control units use this feedback to dynamically adjust discharge currents, reducing current draw from cells with lower charge while maintaining power supply continuity, thus preventing over-discharge while ensuring uninterrupted power delivery
3Reliability
If conventional battery management systems use transformers with multiple secondary windings to balance battery cells, then energy can be transferred between cells, but the balancing efficiency is degraded because even cells with maximum voltage receive corresponding current
Solution Approach 1:
The system implements local quality control by providing different charging/discharging currents to different battery modules based on their specific state of charge. Detection and control units independently manage each module, allowing cells with maximum voltage to receive minimal or zero balancing current while cells with lower voltage receive appropriate current, thereby improving balancing efficiency and reducing energy loss
Solution Approach 2:
The battery management system dynamically adjusts the number of active secondary windings and their connection configurations based on real-time cell voltage measurements. This dynamic adaptation allows the system to optimize energy transfer paths, directing current only where needed to achieve balance, thus improving balancing efficiency while maintaining voltage balance across all cells
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 effectively balances battery cells, preventing over-charging and over-discharging, thereby improving charging efficiency, extending battery life, and ensuring balanced energy distribution within the battery pack.
Implementation Method 1
When the switch 108 is turned on, a discharging current IDISCHG flows from the battery pack 102 to the primary winding 104. Energy can be accumulated in a magnetic core of the transformer temporarily. When the switch 108 is turned off, currents I1, I2, I3, . . . and IM are respectively induced in the secondary winding 106_1-106_M and flow to the battery cells 102_1-102_M. Thus, the energy stored in the magnetic core can be released to the battery cells 102_1-102_M.
Data Source
AI summary
A method for balancing multiple battery cells which are grouped into multiple battery modules includes: obtaining cell parameters of the battery cells, respectively; calculating an average cell parameter for each of the battery modules according to the cell parameters; identifying a donator module and a receiver module from the battery modules based upon the average cell parameter; and transferring energy from the donator module to the receiver module to balance the battery cells.