Flow Battery SOC Detection and Dynamic Voltage Control
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Solution Overview
Problem
Flow batteries face inaccuracies in state of charge (SOC) detection due to electrolyte concentration gradients, inefficient electrolyte flow control, and inadequate heat dissipation, leading to reduced performance and capacity decay.
Innovation Solution
Implementing SOC detection devices at cell stack outlets, calculating SOC based on volume changes in storage tanks, and adjusting electrolyte flow rates and voltages according to operating parameters, while utilizing natural and forced heat dissipation methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SOC detection is performed only at inlet or outlet of cell stack, then detection method is simple, but detection accuracy is low and cannot reflect actual SOC of flow battery
Solution Approach 1:
The electrolyte storage tank is segmented into multiple regions with different SOC levels (high SOC region near inlet, low SOC region near outlet). Multiple detection devices are distributed at different positions (inlet, outlet, and intermediate positions) to measure SOC in different segments, providing a comprehensive view of the overall SOC distribution rather than relying on a single measurement point.
Solution Approach 2:
The patent introduces intermediate detection positions between the inlet and outlet of the cell stack. These intermediate positions act as mediators to capture the SOC gradient information that exists within the electrolyte storage tank, allowing for a more accurate calculation of the average SOC by combining measurements from multiple points.
2Productivity
If circulation pump is controlled only according to output power requirements, then control system is simple, but power consumption is high and efficiency is reduced
Solution Approach 1:
The circulation pump control is changed from a static, fixed-speed operation to a dynamic, variable-speed operation. The pump speed is continuously adjusted based on real-time feedback from multiple SOC detection devices, temperature sensors, and power requirements, allowing the system to optimize electrolyte flow rates and minimize energy consumption while maintaining efficient battery operation.
Solution Approach 2:
The system implements a closed-loop feedback control mechanism where SOC detection devices, temperature sensors, and power management units continuously monitor system parameters and send signals to the circulation pump controller. This feedback loop enables the pump to automatically adjust its operation to match actual battery needs, reducing unnecessary energy consumption while maintaining optimal performance.
3Reliability
If fixed upper limit voltage is set for charging, then charge cutoff control is simple, but capacity decay occurs due to side reactions under high SOC condition
Solution Approach 1:
The charge cutoff voltage is changed from a fixed value to a dynamic, adjustable parameter. The upper limit voltage is continuously adjusted based on real-time SOC measurements from multiple detection devices. When SOC reaches a predetermined threshold, the system dynamically lowers the charge cutoff voltage to prevent overcharging and side reactions, thereby protecting battery capacity without requiring complex additional hardware.
4Reliability
If heat dissipation is not fully considered, then system design is simpler, but long-term thermal shock harms material performance and reduces reliability
Solution Approach 1:
The patent introduces heat dissipation plates as intermediary components between the battery cells and the environment. These plates serve as thermal mediators that facilitate heat transfer from the battery cells to the surrounding air or cooling medium, preventing excessive temperature buildup and thermal shock to battery materials while maintaining a relatively simple overall system design.
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
Accurately determines SOC, optimizes electrolyte flow, reduces power consumption, and prevents capacity decay by dynamically adjusting voltage limits and heat management.
Implementation Method 1
the electrolyte in the positive and negative electrolyte storage tanks flows through liquid delivery pipelines and cell stacks under the impetus of a circulation pump
Implementation Method 2
undergoes an electrochemical reaction in the cell stacks
Implementation Method 3
The flow battery generates a certain amount of heat during the charging and discharging operations
Data Source
AI summary
A flow battery has a control system and a control method to control the operation of the flow battery. The control method includes disposing an SOC detection device respectively at a positive electrolyte outlet and a negative electrolyte outlet of a cell stack; obtaining, by the SOC detection devices, SOCs at the electrolyte outlets of the cell stack under an initial state of the flow battery; at every preset time, acquiring the volume of electrolyte in the positive electrolyte storage tank, the volume of electrolyte in the negative electrolyte storage tank, the volume of the electrolyte flowing into the positive electrolyte storage tank, and the volume of the electrolyte flowing into the negative electrolyte storage tank, and meanwhile, obtaining, by the SOC detection devices, SOCs at the electrolyte outlets of the cell stack; and obtaining SOC of the flow battery.