Curvilinear PM Rotor Layout for Low-Demagnetization Electric Machines
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Solution Overview
Problem
Existing permanent magnet electric machines face challenges in achieving high power density without relying on rare earth metals or iron/ferrous materials, and they suffer from demagnetization issues at elevated temperatures, limiting their efficiency and lifespan.
Innovation Solution
The development of axially-magnetized curvilinear permanent magnets that reduce or eliminate the use of rare earth materials and iron/ferrous components, utilizing low-coercivity magnetic materials like AlNiCo, and employing a novel manufacturing process to create a rotor configuration with a high length-to-cross-sectional area ratio, which aligns the magnetic field vector with the magnetization direction, minimizing demagnetization effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If rare earth magnets (neodymium) are used to achieve high power density, then power density increases, but cost increases and supply chain reliability deteriorates
Solution Approach 1:
The patent changes the material parameters by using ferrite magnets instead of rare earth magnets, and alters the magnetic circuit design parameters to accommodate lower coercivity materials. This substitution resolves the supply chain reliability issue while maintaining power density through optimized magnetic flux paths.
Solution Approach 2:
The patent applies local quality by using back iron specifically in regions where flux concentration is needed, rather than uniformly throughout the entire magnetic circuit. This localized use of ferrous materials optimizes flux direction and concentration only where necessary, reducing overall weight while maintaining performance.
2Reliability
If ferrite magnets are used to reduce cost and eliminate rare earth materials, then cost decreases and supply chain reliability improves, but power density decreases
Solution Approach 1:
The patent changes the magnetic circuit geometry parameters including magnet shape, size, and arrangement to optimize flux paths for ferrite magnets. By adjusting these parameters, the design compensates for the lower intrinsic performance of ferrite materials and achieves competitive power density.
Solution Approach 2:
The patent employs curved or arc-shaped magnet arrangements and magnetic flux paths rather than straight-line configurations. This curvature optimization improves flux utilization and concentrates magnetic fields more effectively, enhancing power density despite using lower-coercivity ferrite materials.
3Power
If iron or ferrous materials are used to direct and concentrate magnetic flux, then magnetic flux concentration improves, but weight increases
Solution Approach 1:
The patent applies back iron locally only in specific regions where flux concentration is required, rather than using it throughout the entire rotor structure. This selective placement minimizes the total amount of ferrous material while maintaining adequate flux concentration for high power density.
Solution Approach 2:
The patent creates a composite magnetic circuit structure combining ferrite magnets with strategic placements of back iron and non-magnetic structural materials. This composite approach optimizes the balance between flux concentration capability and overall weight by using each material only where it provides the most benefit.
4Adaptability or versatility
If permanent magnet electric machines operate at elevated temperatures, then operational flexibility improves, but demagnetization increases reducing reliability
Solution Approach 1:
The patent changes the material selection parameters by choosing ferrite magnets with appropriate temperature characteristics and adjusting the magnetic circuit design parameters to reduce demagnetizing fields. These parameter changes enable stable operation at elevated temperatures by preventing excessive demagnetization.
Solution Approach 2:
The patent designs the magnetic circuit to preemptively counteract demagnetization effects by optimizing flux paths that minimize reverse magnetic fields on the magnets. This preliminary design approach prevents demagnetization before it occurs, enabling reliable high-temperature operation.
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 solution enables electric machines to operate at high temperatures with reduced demagnetization, increased power density, and lower costs, while eliminating the need for expensive rare earth materials and heavy iron components, making them suitable for applications like aircraft propulsion systems.
Implementation Method 1
axially-magnetized curvilinear permanent magnets that reduce or eliminate the use of rare earth materials and iron/ferrous components, utilizing low-coercivity magnetic materials like AlNiCo
Data Source
AI summary
A configuration of a plurality of elongate, axially-magnetized curvilinear permanent magnets having high length to cross-section ratio, produced, for example, by the PM-Wire manufacturing process, that produce an electric machine permanent magnet rotor structure with a very low intrinsic demagnetizing field, allowing for operation at high temperature, at high RPM, or enabling use of permanent magnets comprising low coercivity magnetic materials. Exemplary embodiments of two-pole, four-pole, six-pole and eight-pole rotor permanent magnet configurations for single and dual rotor applications. The novel configuration of axially-magnetized curvilinear permanent magnets reduces demagnetization at high temperature, increases electric machine power density, reduces weight by eliminating the need for back iron, increases motor reliability, reduces manufacturing costs, and enables higher electric motor torque and electric generators. Electric machines, rotors and magnets of the invention may contain no rare earth magnetic materials.