Battery Voltage Control via Cell Quality Factor Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery systems face challenges in accurately adapting the actual output voltage to a target voltage due to deviations in battery cell capacitance and internal resistance, leading to undesirable outliers in output voltage.
Innovation Solution
A method that generates both switch-on and switch-off probabilities for connecting or bypassing battery cells, with these probabilities determined by functions dependent on the difference between the target and actual output voltage, ensuring that battery cells are either connected or bypassed based on their quality factors, such as state of charge and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery cells are randomly switched on and off to adapt output voltage, then the target output voltage can be achieved on average, but strong deviations of actual output voltage from target voltage occur
Solution Approach 1:
The patent changes the control parameter from simple random switching to quality factor-based switching with separate switch-on and switch-off probabilities. Each battery cell is assigned a quality factor based on its individual characteristics (capacitance, internal resistance, state of charge), and switching decisions are made based on both the quality factor and the current voltage deviation, thereby reducing strong deviations while maintaining target voltage achievement.
Solution Approach 2:
The patent performs preliminary assessment of each battery cell's quality factor before switching decisions are made. By pre-evaluating cell characteristics and assigning quality factors, the system can make informed switching decisions that prevent strong deviations, rather than relying on random switching alone.
2Adaptability or versatility
If battery cells with deviations in capacitance and internal resistance are used, then production flexibility is improved, but states of charge deviate from one another leading to voltage control issues
Solution Approach 1:
The patent applies local quality by assigning individual quality factors to each battery cell based on its specific characteristics (capacitance, internal resistance, state of charge). This allows each cell to be evaluated and controlled according to its own properties rather than treating all cells uniformly, thereby maintaining voltage consistency despite cell variations.
Solution Approach 2:
The patent changes the control approach by introducing quality factor as a new parameter that incorporates individual cell characteristics. This parameter transformation allows the system to accommodate cell variations while maintaining overall voltage control through differentiated switching probabilities based on each cell's quality factor.
3Device complexity
If only switch-on probability is used for controlling battery cell connections, then the control mechanism is simple, but undesirable outliers in output voltage occur
Solution Approach 1:
The patent segments the control mechanism into two independent probability functions: switch-on probability and switch-off probability. This segmentation allows separate optimization of each switching direction, preventing voltage outliers by controlling the asymmetry in switching behavior while maintaining overall system simplicity.
Solution Approach 2:
The patent introduces dynamic control by making both switch-on and switch-off probabilities dependent on the current voltage deviation from target. This dynamic adjustment allows the control mechanism to adapt to real-time conditions, improving voltage stability without significantly increasing system complexity.
Data Source
AI summary
The present invention relates to a method for controlling an output voltage of a battery system comprising a plurality of battery cells, which are electrically interconnected in such a way that battery cells of the battery system can respectively be connected to the battery system and can be electrically bypassed. In order to adapt an actual output voltage of the battery system to a target output voltage, at least one switch-on probability is generated and the battery cells having the at least one generated switch-on probability are connected to the battery system and additionally at least one switch-off probability is generated and the battery cells having the at least one generated switch-off probability are electrically bypassed. The present invention further relates to a battery system designed to carry out the method according to the invention, comprising a plurality of electrically interconnected battery cells a plurality of activation circuits, and a control unit, wherein the battery cells can be respectively connected to the battery system or electrically bypassed by means of the activation circuits.