Dynamic SOC Threshold Adjustment for Battery Cell Management
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Solution Overview
Problem
Electric vehicles powered by batteries face challenges such as frequent recharging needs, space requirements for spare batteries and charging equipment, and performance degradation as batteries deplete, while fuel cell systems offer cost savings but require careful management to avoid overcharging and over-discharging, which can lead to system failures.
Innovation Solution
A method for managing the state of charge (SOC) of battery cells in hybrid fuel cell systems by calculating individual cell SOC, defining minimum and maximum thresholds, and adjusting the number of cells used to calculate the overall SOC based on average SOC levels, ensuring that cells with the lowest SOC are not over-discharged and those with the highest SOC are not overcharged, using weighted calculations to determine the overall SOC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a battery is fully charged to maximize energy storage, then the energy capacity is improved, but the risk of overcharging and system failure increases
Solution Approach 1:
The patent dynamically changes the charging parameters (SOC thresholds) based on operating conditions. The maximum SOC threshold is adjusted from a fixed value to a variable parameter that changes with temperature, load conditions, and battery age, allowing the system to maximize energy storage while maintaining safety margins under different operating conditions
Solution Approach 2:
The system continuously monitors individual cell voltages, temperatures, and SOC levels, and uses this feedback to adjust charging currents and voltage thresholds in real-time. The control system modifies charging parameters based on feedback from voltage sensors and temperature sensors to prevent overcharging while maximizing energy utilization
2Loss of energy
If the battery SOC is managed to accept regenerative energy, then the energy recovery is improved, but the risk of voltage rise and system damage increases
Solution Approach 1:
The patent implements dynamic SOC threshold adjustment during regenerative braking events. The maximum SOC threshold is temporarily reduced when regenerative energy capture is anticipated, allowing the system to dynamically adapt to varying energy recovery opportunities while preventing voltage overcharge conditions
Solution Approach 2:
The system takes preliminary action by pre-setting reduced SOC thresholds before regenerative events occur. When regenerative braking is detected or anticipated, the control system proactively lowers the maximum SOC threshold to create a safety buffer, preventing voltage rise before it becomes a harmful condition
3Measurement precision
If individual cell monitoring is implemented to improve SOC accuracy, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent divides the battery system into individual cell segments, each with its own voltage and temperature monitoring. By segmenting the monitoring approach and using a multiplexer to sequentially measure each cell, the system achieves high measurement precision without requiring a separate dedicated sensor for each cell, thus managing complexity
Solution Approach 2:
The control system performs multiple functions using a single integrated unit: it monitors voltage, temperature, calculates SOC, determines charging thresholds, and controls charging currents for all cells. This multi-functional approach reduces overall system complexity compared to having separate dedicated systems for each function
Data Source
AI summary
Embodiments of the disclosure may include a method of managing a state of charge of a battery having a plurality of battery cells. The method may include calculating an individual state of charge for each battery cell, calculating an average state of charge for the battery cells, defining a minimum and a maximum average state of charge threshold, and calculating an overall state of charge for the battery such that when the average state of charge is below the minimum threshold, the overall state of charge is calculated based on the state of charge of a subset of battery cells having the lowest state of charge, and when the average state of charge is above the maximum threshold, the overall state of charge is calculated based on the state of charge of a subset of battery cells having the highest state of charge.