Flow Battery Stack Topology for Efficient EV Charging Voltage Matching
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Solution Overview
Problem
Electric vehicle charging systems face inefficiencies due to high buck or boost ratios in DC/DC converters, requiring close proximity of power reservoirs to the vehicle and experiencing self-discharging from spontaneous chemical reactions in lithium-ion batteries.
Innovation Solution
An electric vehicle charging system utilizing an electrolyte flow system with anolyte and catholyte solutions, a core stack circuit, and a DC/DC converter module that controls voltage by adjusting flow rates and selectively connecting/disconnecting flow battery core stacks to optimize charging voltage and reduce conversion losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If DC/DC converters with high buck or boost ratios are used to increase voltage in the power reservoir, then the charging voltage requirement is met, but the charging system efficiency decreases
Solution Approach 1:
The power reservoir is divided into multiple modular flow battery core stacks that can be selectively connected in series or parallel. This segmentation allows the system to achieve the required charging voltage through direct series connection of stacks rather than using high-ratio DC/DC converters, thereby maintaining high charging efficiency while meeting voltage requirements.
Solution Approach 2:
The system dynamically reconfigures the connection topology of flow battery core stacks based on real-time charging voltage and current requirements. By selectively connecting stacks in series or parallel configurations, the system adapts its output voltage and current to match the EV battery pack requirements directly, eliminating the need for inefficient high-ratio voltage conversion.
2Temperature
If power reservoirs are placed close to the EV charging head, then voltage drop in high-voltage DC links is reduced, but the system requires close spatial proximity which limits flexibility
Solution Approach 1:
The power reservoir is segmented into multiple modular flow battery core stacks that can be distributed and reconfigured. This modular architecture allows the system to maintain low voltage drop through direct series connection while providing flexible spatial arrangement, as each module can be independently positioned and connected based on installation constraints.
3Quantity of substance
If lithium-ion batteries are used as power reservoirs, then energy storage is achieved, but self-discharging occurs due to spontaneous internal chemical reactions
Solution Approach 1:
The patent extracts the energy storage function from conventional lithium-ion batteries and implements it using flow batteries with separate electrolyte tanks. This extraction eliminates the self-discharge problem inherent in sealed lithium-ion batteries by using a different electrochemical system where energy is stored in external electrolyte reservoirs rather than within sealed battery cells.
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 approach reduces the need for close proximity of power reservoirs, minimizes self-discharge, and enhances charging efficiency by lowering buck and boost ratios, thereby increasing the system's efficiency and reducing costs.
Implementation Method 1
a core stack circuit coupled to the electrolyte flow system. The core stack circuit may comprise a plurality of flow battery core stacks configured to receive the anolyte solution and the catholyte solution and to generate a flow battery core stack output voltage and current based on the flow rates of the anolyte solution and the catholyte solution
Implementation Method 2
a DC/DC converter module comprising a plurality of DC/DC converters. The DC/DC converter module may be coupled to the core stack circuit and configured to receive the flow battery core stack output voltage and current. The DC/DC converter module may be further configured to buck or boost the flow battery core stack output voltage
Data Source
AI summary
Embodiments disclosed herein include an electric vehicle charging system comprising an electrolyte flow system including an anolyte tank having an anolyte solution and a catholyte tank having a catholyte solution. A core stack circuit may be coupled to the electrolyte flow system that is configured to receive the anolyte and catholyte solutions and generate a core stack output voltage and current based on flowrates of the anolyte and catholyte solutions. The EV charging system may further include a DC/DC converter that is configured to receive the core stack output voltage and buck or boost the core stack output voltage based on the core stack output voltage and a charging voltage of an EV. The flowrates of the anolyte and catholyte solutions may be controlled based on a charging voltage of the EV and the core stack output voltage, which can reduce a buck or boost ratio of the DC/DC converter.