Battery Charge Management via Cell Isolation and Balancing
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Solution Overview
Problem
Existing methods for managing the charge of unit cells in connected batteries, particularly in complex configurations, fail to effectively balance voltages across multiple batteries, leading to uneven stress on cells and reduced system lifetime, and lack safety measures during balancing operations.
Innovation Solution
A method that involves measuring and comparing voltages across all unit cells, disconnecting batteries with cells to be balanced to isolate them, and using a passive balancing process to equalize voltages by discharging cells through a resistor, ensuring all cells operate at the same level and reducing stress, thereby extending battery life and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage balancing is performed on unit cells in connected batteries without isolation, then voltage equalization can be achieved, but safety risks increase due to potential interference with other batteries
Solution Approach 1:
The patent extracts and isolates the battery containing the unit cell with the lowest voltage from the connected battery system before performing voltage balancing. This isolation prevents interference with other batteries during the balancing process, thereby improving safety while maintaining manageable complexity through controlled disconnection.
Solution Approach 2:
The patent performs preliminary identification and isolation of the battery to be balanced before the actual voltage balancing operation. By measuring voltages of all unit cells first and disconnecting the relevant battery in advance, the system ensures safe operating conditions are established before the balancing process begins.
2Productivity
If voltage balancing is performed on all unit cells simultaneously, then balancing efficiency improves, but uneven stress on cells during balancing reduces system lifetime
Solution Approach 1:
The patent segments the voltage balancing process by first identifying and isolating the specific battery containing the unit cell with the lowest voltage, then performing balancing only on that isolated battery. This segmentation allows efficient targeted balancing while preventing uneven stress propagation across the entire system, thereby extending system lifetime.
Solution Approach 2:
The patent applies local quality by focusing the voltage balancing operation specifically on the isolated battery containing the lowest voltage unit cell, rather than uniformly balancing all batteries. This localized approach optimizes balancing efficiency for the critical component while minimizing unnecessary stress on other healthy cells.
3Device complexity
If average voltage measurement is used for balancing, then system complexity is reduced, but balancing effectiveness decreases leading to optimized lifetime
Solution Approach 1:
The patent implements a feedback mechanism by measuring the voltages of all unit cells in connected batteries, identifying the lowest voltage, and using this precise information to guide the balancing process. This feedback-based approach ensures high balancing precision by targeting the specific cell that needs balancing, rather than using crude average voltage measurements.
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 method effectively balances voltages across multiple batteries, reducing cell stress, extending battery life, and improving safety by ensuring all cells operate at the same voltage, regardless of the battery system architecture, and is simple to implement with standard electrochemical cells equipped with balancing devices.
Implementation Method 1
The voltage balancing step consists in discharging all the unit cells exhibiting a voltage greater than the minimum voltage, until all the unit cells exhibit a voltage equal to the minimum voltage
Data Source
Figure 1
AI summary
Method for charge management of units cells of a plurality of batteries interconnected with one another, the method comprising the steps consisting of: - measuring a voltage across the terminals of each unit cell of each of the plurality of batteries, - comparing the measurements of each unit cell with one another in order to determine a lowest voltage of all the unit cells of the plurality of batteries, - equalising the voltages of the unit cells for which the voltage is greater than the lowest voltage, taking as a target the lowest voltage so as to reduce a variation between the voltage of each unit cell and the lowest measured voltage, wherein the step consisting of equalising the voltages of the unit cells having a voltage greater than the lowest voltage is preceded by a step consisting of disconnecting from the other batteries at least one battery comprising a unit cell for which the voltage is to be equalised.