Battery Equalization Circuit for Assembled Cell Voltage Imbalance
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Solution Overview
Problem
Assembled battery devices in electric vehicles experience voltage imbalance among secondary battery cells due to self-discharge differences, leading to reduced effective capacity when discharged or charged, as cells with varying remaining capacities reach voltage limits prematurely.
Innovation Solution
A power source device with a battery management unit and discharge circuits that perform constant current and voltage charging, and equalization processing to balance cell voltages by discharging cells that reach specific voltages, ensuring all cells reach full charge state effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If constant current charging is performed on assembled battery devices with voltage imbalance among secondary battery cells, then charging speed is improved, but cells with large remaining capacity reach voltage upper limit prematurely, reducing effective capacity
Solution Approach 1:
The discharge circuits perform equalization processing by discharging cells with large remaining capacity before or during the charging process. This preliminary action balances the voltage among cells, ensuring that when constant current charging begins, all cells can be charged to full capacity without premature voltage limit reaches, thus maintaining effective capacity while achieving fast charging
2Quantity of substance
If discharge circuits are added to perform equalization processing, then effective capacity is maintained, but device complexity increases
Solution Approach 1:
The discharge circuits are designed to serve multiple functions: they perform equalization processing by discharging cells with large remaining capacity, and they can also be used during normal operation to maintain voltage balance. This multi-functionality justifies the added complexity by providing ongoing benefits for maintaining effective capacity throughout the battery's operational life
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 solution maintains the effective capacity of assembled battery devices by ensuring all secondary battery cells are fully charged, preventing premature voltage limit reaches and optimizing battery performance.
Implementation Method 1
a discharge circuit for discharging the secondary battery cell when the voltage of the secondary battery cell has reached a prescribed first voltage
Implementation Method 2
perform constant current charging to the assembled battery; when voltages of one or a plurality of the secondary battery cells out of the plurality of the secondary battery cells have reached a prescribed first voltage
Implementation Method 3
perform constant voltage charging to the assembled battery; when voltage of the secondary battery cell during being discharged has reached a prescribed second voltage lower than the first voltage
Data Source
AI summary
A power source device includes an assembled battery having a plurality of secondary battery cells connected in series, and a plurality of discharge circuits connected in parallel with the secondary battery cells, respectively. A charge control circuit performs constant current charging to the assembled battery, and when voltages of one or a plurality of the secondary battery cells out of the plurality of secondary battery cells have reached a prescribed first voltage, drives the discharge circuits connected to the secondary battery cells whose voltage have reached the first voltage to discharge, and performs constant voltage charging to the relevant assemble battery.