Composite Permanent Magnet Phase Coupling
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Solution Overview
Problem
Existing permanent magnet motors, particularly those using rare-earth magnets, face challenges in achieving optimal magnetic properties such as high coercivity, magnetic flux density, and energy product, which are crucial for efficient operation in traction motors for hybrid and electric vehicles.
Innovation Solution
A composite permanent magnet is designed with a first phase of magnetically hard material and a second phase of magnetic material, where the ratio of their magnetocrystalline anisotropy values falls within a predefined range, and the grain size of the magnetic material is greater than 20 nanometers, enhancing magnetic properties like coercivity and energy product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare-earth permanent magnets are used to achieve high flux density and high anti-demagnetizing ability, then magnetic performance is improved, but cost and resource availability worsen due to large amounts of rare-earth elements required
Solution Approach 1:
The patent employs a composite permanent magnet structure consisting of a magnetically hard phase (e.g., NdFeB) and a magnetically soft phase (e.g., Fe-Co alloy). This composite approach allows the system to achieve high magnetic performance through synergistic interaction between phases, specifically through exchange coupling at grain boundaries. The magnetically soft phase enhances saturation magnetization while the hard phase provides coercivity, reducing the overall rare-earth content needed while maintaining or improving magnetic properties.
Solution Approach 2:
The patent systematically varies critical parameters including grain size (controlling exchange coupling strength), phase composition ratios, and magnetocrystalline anisotropy values to optimize magnetic performance. By adjusting grain size to specific ranges and controlling the volume fraction of hard and soft phases, the invention achieves optimal balance between coercivity and saturation magnetization, thereby reducing rare-earth element requirements while maintaining high magnetic performance.
2Reliability
If grain size is reduced to enhance exchange coupling and magnetic properties, then magnetic performance is improved, but manufacturing precision worsens due to difficulty in controlling small grain sizes
Solution Approach 1:
The patent identifies and controls critical parameters including grain size, phase composition, and magnetocrystalline anisotropy to optimize magnetic properties while maintaining manufacturability. By establishing specific parameter ranges (e.g., grain size thresholds, anisotropy ratios) rather than requiring precise single-value control, the invention provides manufacturing flexibility while achieving desired magnetic performance.
Solution Approach 2:
The patent creates distinct regions with different properties: the magnetically hard phase provides high coercivity while the magnetically soft phase provides high saturation magnetization. The grain boundary regions between phases are engineered to facilitate exchange coupling. This local differentiation of properties allows each phase to be optimized independently for its specific function, simplifying overall manufacturing control.
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 composite magnet exhibits improved magnetic properties, including higher coercivity and energy product, comparable to or exceeding those of rare-earth magnets, while maintaining resistance to demagnetization, thus enhancing the efficiency of electric motors.
Implementation Method 1
Each of the materials has an anisotropy value selected such that a ratio of the values falls within a predefined range
Implementation Method 2
magnetic phase coupling in a composite permanent magnet
Implementation Method 3
a rotor including a plurality of permanent magnets causing the rotor to travel according to attraction and repulsion forces between the magnets and the field
Data Source
AI summary
A composite permanent magnet comprises a first phase including a magnetically hard material and a second phase including a magnetic material. Each of the materials has an anisotropy value selected such that a ratio of the values falls within a predefined range and a resulting grain size of the magnetic material is greater than a predefined threshold defined by the predefined range.