Wire-Wound Flywheel Rotor for High Energy Density Storage
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Solution Overview
Problem
Current flywheel energy storage systems face limitations in energy storage capacity due to the low tensile strength of forged steel rotors and the complexity and cost of composite rotors, which require thicker structures and higher operational speeds to store energy effectively.
Innovation Solution
A wire-wound rotor design using preloaded steel wire wound onto a flywheel core, where the outermost wire layer exerts a compressive radial force throughout the operational speed range, enhancing the structural integrity and energy storage capacity while allowing for a more efficient manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If forged steel rotors are used, then manufacturing is simpler and cost is lower, but tensile strength is limited and energy storage capacity is reduced
Solution Approach 1:
The patent applies composite materials by combining steel wire (providing tensile strength) with a matrix material such as epoxy resin or polyester resin (providing structural integrity and ease of manufacture). This composite structure allows the rotor to achieve high tensile strength necessary for energy storage while maintaining manufacturing simplicity through conventional composite fabrication processes.
2Strength
If composite rotors are used, then tensile strength increases and energy storage capacity improves, but fabrication complexity increases and manufacturing cost rises
Solution Approach 1:
The patent applies local quality by varying the fiber orientation and density in different regions of the rotor. The composite structure uses specific winding patterns where fibers are concentrated in high-stress areas, allowing the rotor to achieve necessary tensile strength only where needed, thereby reducing overall material usage and simplifying fabrication processes.
Solution Approach 2:
The patent applies segmentation by dividing the rotor into discrete wire-wound layers or segments that can be manufactured and assembled separately. This modular approach reduces fabrication complexity by allowing each segment to be produced using standardized processes, then combined to form the complete rotor structure.
3Quantity of substance
If composite rotors are made thicker to store energy, then energy storage capacity increases, but fabrication time and cost increase significantly
Solution Approach 1:
The patent applies parameter changes by optimizing the rotor's geometric parameters, specifically the wire diameter, winding tension, and layer configuration. By carefully selecting these parameters, the rotor achieves maximum energy storage capacity in a thinner profile, reducing the number of layers required and thereby decreasing fabrication time and associated costs.
4Device complexity
If composite rotors are made thinner to reduce fabrication complexity, then manufacturing becomes easier, but more mass must be added axially or higher speeds are required
Solution Approach 1:
The patent applies dynamics by designing the rotor to operate at optimized rotational speeds that take advantage of centrifugal forces. The wire-wound composite structure is engineered to withstand and utilize these dynamic loads, allowing a thinner rotor design to achieve the necessary structural integrity through dynamic stress distribution rather than relying solely on increased static material thickness.
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 wire-wound rotor design increases energy storage density and reduces manufacturing complexity, enabling higher energy storage per unit mass and volume, and extends the operational speed range without compromising structural integrity.
Implementation Method 1
The wire is preloaded such that the outermost layer of wire exerts a net radial force that is compressive throughout the operational speed range of the flywheel
Implementation Method 2
in order to store appreciable energy, flywheel rotors are typically much thicker than other cylindrical composite structures, such as pressure vessels
Data Source
AI summary
A flywheel is described having a rotor constructed of wire wound onto a central form. The wire is prestressed, thus mitigating stresses that occur during operation. In another aspect, the flywheel incorporates a low-loss motor using electrically non-conducting permanent magnets.