Flywheel Rotor Back Iron with Low Conductivity Composite
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Solution Overview
Problem
Conventional energy storage solutions, such as batteries and capacitors, are inadequate for handling high-power, short-duration power fluctuations due to limited cycle life and inefficiencies, while pumped hydro storage is not compact or transportable, and existing flywheel systems struggle with continuous high-power cycling.
Innovation Solution
A flywheel energy storage system with a rotor back iron made of a composite material having high relative permeability and low electrical conductivity, supported by a composite structure, allowing for continuous operation at over 200 kW with minimal on-rotor losses, and incorporating a built-in motor-generator for efficient energy conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional energy storage solutions (batteries, capacitors) are used, then they can provide energy storage capability, but they have limited cycle life and cannot withstand long-term operation with frequent cycling
Solution Approach 1:
The patent employs composite materials in the flywheel rotor construction, combining different materials to achieve both high strength for withstanding centrifugal forces during frequent cycling and appropriate magnetic properties for efficient energy storage. The composite structure allows the system to endure over 1,000,000 charge-discharge cycles while maintaining performance.
2Power
If existing flywheel systems operate at high power levels, then they can provide necessary power output, but excessive rotor heating occurs due to inefficiencies and losses
Solution Approach 1:
The patent optimizes various parameters including magnetic circuit design, electrical conductivity of materials, and mechanical losses to minimize energy losses that convert to heat. By carefully selecting materials with appropriate electrical conductivity and designing the magnetic circuit to reduce eddy current losses, the system maintains efficient operation at high power levels without excessive rotor heating.
3Quantity of substance
If pumped hydro storage is used for energy storage, then it can provide large-scale storage capability, but it is not compact or transportable
Solution Approach 1:
The patent replaces the large-scale mechanical pumped hydro system with a compact flywheel energy storage system that uses rotational kinetic energy. This substitution enables MW-scale energy storage capability in a much smaller, transportable unit that can be deployed in diverse locations without requiring large geographic footprints or civil infrastructure.
4Quantity of substance
If batteries are sized to store sufficient energy for power management applications, then they can provide adequate energy capacity, but they become costly and require periodic replacement due to degradation
Solution Approach 1:
The patent uses composite materials in the flywheel rotor to achieve both the structural integrity needed for high-speed rotation and the magnetic properties required for efficient energy storage. This composite construction provides superior durability with over 1,000,000 cycle life, eliminating the need for periodic replacement and reducing long-term costs compared to battery systems.
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 achieves high cycle life, rapid response, and compactness, enabling MW-scale charge and discharge capabilities without degradation, making it suitable for diverse applications with minimal energy losses.
Implementation Method 1
The rotor back iron is formed of a material having a first stiffness, relative permeability of at least 10, and an electrical conductivity 10% or less than the electrical conductivity of magnetic steel
Implementation Method 2
an electrical conductivity 10% or less than the electrical conductivity of magnetic steel
Implementation Method 3
configured to rotationally accelerate to convert electrical energy into kinetic energy during a charging mode and to rotationally decelerate to convert kinetic energy into electrical energy during a discharging mode
Implementation Method 4
the composite structure comprises a composite material having a second stiffness, which is greater than the first stiffness of the rotor back iron
Data Source
AI summary
A flywheel energy storage system includes a rotating assembly having a plurality of magnets and a longitudinal axis about which the rotating assembly rotates and static assembly having a stator configured to magnetically interact with the plurality of magnets of the rotating assembly. The rotating assembly includes a rotor back iron supporting the plurality of magnets and disposed further from the longitudinal axis in a radial direction than the plurality of magnets. The back iron being formed of a material having a first stiffness, relative permeability of at least 10, and an electrical conductivity 10% or less than the electrical conductivity of magnetic steel. There is composite structure supporting the rotor back iron and disposed further from the longitudinal axis in a radial direction than the rotor back iron. The composite structure comprises a composite material having a second stiffness, which is greater than the first stiffness.