Redox Flow Battery Voltage Balancing via Closed Loop Switching
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Solution Overview
Problem
When redox flow battery cell parts are connected in parallel, some battery cell parts become overcharged due to non-uniform electrolyte distribution, leading to voltage differences and potential overcharging, even when there is no charge or discharge occurring with the power system.
Innovation Solution
A redox flow battery system with plural branch circuits, a switching unit, a circulation mechanism, a detection unit, and a control unit that monitors open circuit voltages and controls the conduction state of the closed loop to prevent overcharging by ensuring uniform electrolyte distribution among battery cell parts connected in parallel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If battery cell parts are connected in parallel to increase power output, then the power supply capability is improved, but voltage differences between cell parts cause overcharging in some cells
Solution Approach 1:
The system continuously monitors the voltage of each battery cell part through detection units and uses this feedback information to control switching units. When voltage differences between parallel-connected cell parts exceed a threshold, the system automatically opens the closed loop to prevent overcharging, and closes it when voltages are balanced, achieving dynamic regulation of charging uniformity while maintaining high power output capability
Solution Approach 2:
The system enables battery cell parts to self-regulate their charging state through the closed loop mechanism. When one cell part reaches higher voltage, current naturally flows to equalize voltages through the closed loop, and the switching unit automatically disconnects when voltage balance is achieved or overcharging risk is detected, allowing the system to self-manage charging distribution without external intervention
2Productivity
If a closed loop is formed by connecting branch circuits in parallel, then electrolyte circulation is improved, but voltage differences cause current flow leading to overcharging
Solution Approach 1:
The system dynamically adjusts the conduction state of the closed loop based on real-time voltage conditions. The switching unit transitions the closed loop between conducting and non-conducting states according to voltage balance requirements, making the system adaptable to changing operating conditions. This dynamic control allows the closed loop to provide electrolyte circulation benefits while preventing harmful current flow that would cause overcharging
Solution Approach 2:
The control system proactively prevents overcharging by monitoring voltage differences before they cause harmful effects. When voltage imbalance exceeds a predetermined threshold, the switching unit opens the closed loop in advance to block potential overcharging current, preventing the harmful effect rather than correcting it after occurrence
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
The system effectively suppresses overcharging by maintaining the closed loop in a non-conducting state when voltage differences exceed a predetermined value, preventing current flow and ensuring uniform electrolyte distribution, thus preventing battery cell parts from becoming overcharged.
Implementation Method 1
a detection unit configured to detect physical quantities correlating with open circuit voltages of the battery cell parts
Implementation Method 2
The circulation mechanism includes a tank configured to store an electrolyte, and a pump configured to circulate the electrolyte from the tank to the battery cell parts
Implementation Method 3
The RF battery is charged and discharged by using the oxidation-reduction potential difference between ions contained in the positive electrode electrolyte and ions contained in the negative electrode electrolyte
Implementation Method 4
The switching unit is configured to switch conduction states of a closed loop in which the branch circuits are connected together
Data Source
AI summary
A redox flow battery system includes a plurality of branch circuits electrically connecting a plurality of battery cell parts in parallel; a switching unit configured to switch conduction states of a closed loop in which the branch circuits are connected together; a circulation mechanism; a detection unit; a determination unit configured to determine whether or not a voltage difference between the open circuit voltages of the battery cell parts is more than a predetermined value; and a control unit configured to control a switching operation of the switching unit such that, when the determination unit determines the voltage difference to be more than the predetermined value, the closed loop is brought into a non-conducting state and, when the determination unit determines the voltage difference to be equal to or less than the predetermined value, the closed loop is brought into a conducting state.