Redox Flow Battery Pump Control for Voltage Stability
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Solution Overview
Problem
Redox flow batteries face issues with pump loss and unstable operation due to variations in terminal voltage, leading to unnecessary stopping of charging and discharging, even when the state of charge is within a range capable of charging and discharging.
Innovation Solution
A pump control unit that adjusts the flow rate of pumps based on the state of charge and terminal voltage, setting a reference flow rate and increasing it when the terminal voltage approaches the voltage limits to prevent it from exceeding the predetermined range, ensuring stable operation and reducing pump loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pump flow rate is controlled to correspond to the state of charge, then pump loss is reduced, but the terminal voltage may momentarily vary and exceed the voltage range, causing unnecessary stopping of charging and discharging
Solution Approach 1:
The control unit continuously monitors terminal voltage and uses this feedback to dynamically adjust pump flow rate. When terminal voltage approaches the voltage range limits, the control unit modifies the pump flow rate to maintain voltage within acceptable boundaries, preventing unnecessary stopping of charging/discharging operations.
Solution Approach 2:
The system transitions from static pump flow rate control (based solely on state of charge) to dynamic control that adapts to real-time terminal voltage conditions. The pump flow rate is continuously adjusted according to both state of charge and terminal voltage measurements, enabling the system to respond to varying operational conditions and maintain stable operation.
2Productivity
If the pump flow rate is set within a specific range to prevent overcharging and overdischarging, then battery efficiency is improved, but terminal voltage variations may still cause charging and discharging to stop
Solution Approach 1:
The system dynamically changes the pump flow rate parameter based on real-time measurements of both state of charge and terminal voltage. By adjusting the flow rate in response to terminal voltage variations, the system maintains voltage within the acceptable range for the power converter, preventing unnecessary stopping while preserving the efficiency benefits of flow rate optimization.
Solution Approach 2:
The control unit acts as an intermediary that coordinates between the state of charge control mechanism and the terminal voltage stability requirement. It processes both parameters and determines the appropriate pump flow rate setting that satisfies both efficiency and continuous operation requirements.
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 allows for continuous charging and discharging without unnecessary stops, reducing pump loss and maintaining stable operation by controlling the pump flow rate in response to both state of charge and terminal voltage variations.
Implementation Method 1
pumps which circulate the electrolytes through the circulation pipes, and a pump control unit which controls the flow rate of the pumps
Implementation Method 2
charging and discharging are performed through a power converter... in which Fe ions are used as the positive electrode active material and Cr ions are used as the negative electrode active material
Implementation Method 3
a battery cell which includes a positive electrode, a negative electrode, and a membrane disposed between the two electrodes
Data Source
AI summary
A redox flow battery system includes pumps, a pump control unit, an SQC measuring unit, and a terminal-voltage measuring unit. The pump control unit includes a reference-flow-rate acquiring unit which acquires a reference flow rate of the pumps corresponding to the state of charge of electrolytes; a terminal-voltage determination unit which determines whether or not a terminal voltage of a battery cell reaches the lower limit or the ripper limit of a predetermined voltage range; and a pump-flow-rate setting unit which sets the reference flow rate for the pumps in the case where the terminal voltage does not reach the upper or lower limit of the predetermined voltage range, and sets a flow rate obtained by adding a predetermined flow rate to the reference flow rate for the pumps in the ease where the terminal voltage reaches the upper or lower limit of the predetermined voltage range.