Nested-Rotor Flywheel with HTS Bearings
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Solution Overview
Problem
Traditional flywheel energy storage devices face limitations in achieving high energy density and efficiency due to material growth-matching issues and radial growth disparities at varying frequencies and speeds, which restrict their maximum energy storage and deployment capacity.
Innovation Solution
The implementation of an open-core flywheel architecture with high-temperature superconducting (HTS) bearings and multiple rotors made from high-strength materials, such as carbon nanotube-containing composites, allowing for increased speed and power storage while minimizing angular momentum and size constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional shaft-and-hub architecture is used, then mechanical coupling is achieved, but radial growth mismatch and bending modes occur at high speeds
Solution Approach 1:
The patent removes the traditional shaft-and-hub architecture entirely, extracting the problematic mechanical coupling components that cause radial growth mismatch. The hubless design eliminates the shaft that connects the rim to the center, thereby eliminating the source of bending modes and radial growth incompatibility at high speeds.
Solution Approach 2:
The patent replaces the mechanical shaft-and-hub coupling system with magnetic bearing support. Instead of mechanical connections that suffer from radial growth mismatch, the rotor is supported by magnetic fields that can accommodate the radial expansion of the carbon fiber rim without introducing bending stresses.
2Power
If higher rotor velocities are achieved, then energy storage capacity increases, but material growth-matching problems worsen
Solution Approach 1:
The patent employs carbon fiber composite materials for the rotor rim that provide exceptional tensile strength and controlled radial expansion characteristics. These composite materials enable the rim to withstand the centrifugal forces at high velocities while maintaining dimensional stability and preventing the radial growth mismatch that plagues traditional materials.
Solution Approach 2:
The patent changes the operational parameters by removing mechanical constraints (shaft and hub) that limited radial expansion. This allows the rotor to operate at higher velocities where the rim's radial growth is accommodated by the magnetic bearing clearance rather than being constrained by mechanical couplings, thereby increasing energy storage capacity.
3Speed
If hubless architecture is implemented, then radial growth and bending mode issues are eliminated, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical coupling systems (shaft, hub, keyways, fasteners) with magnetic bearing systems. While magnetic bearings introduce electromagnetic complexity, they eliminate the mechanical complexity of high-speed couplings and eliminate bending modes, resulting in a simpler overall system that can operate at higher velocities without mechanical failure.
4Speed
If high-strength materials are used, then rotor velocity increases, but manufacturing and material matching becomes more difficult
Solution Approach 1:
The patent uses carbon fiber composite materials that can be manufactured in large-diameter rims without the need for complex material matching. The composite structure allows for uniform radial expansion characteristics throughout the rim, eliminating the material matching problems that arise when assembling multiple components with different thermal and mechanical expansion coefficients.
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 configuration significantly enhances flywheel performance by achieving higher speeds, increased power storage and generation, and improved durability, resulting in higher energy and power density with reduced size, thus overcoming the limitations of traditional shaft-and-hub designs.
Implementation Method 1
high-temperature superconducting (HTS) bearings
Implementation Method 2
passively stable magnetic bearing comprising a permanent magnet (PM) lift bearing
Implementation Method 3
carbon fiber, glass fiber, metals, and combinations thereof
Implementation Method 4
One particularly preferred material is a carbon nanotube-containing material
Data Source
Figure 1a~2
Figure 3~4
Figure 5~6
AI summary
Methods and apparatuses are disclosed for incorporating a plurality of independently rotating rotors made from high-strength materials with a high-temperature superconductive (HTS) bearing technology into an open-core flywheel architecture to achieve a desired high energy density in the flywheel energy storage devices and to obtain superior results and performance.