Series Magnet Circuit Layout for Torque Without Demagnetization
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Solution Overview
Problem
Existing permanent magnets in electrical machines face challenges with demagnetization due to high demagnetizing magnetic fields, which can lead to increased costs and reduced torque production when using high coercivity and remanence magnets.
Innovation Solution
A series combination of a first magnet with high coercivity and a second magnet with lower coercivity is used, where the dimensions of the magnets are selected such that the flux density in the second magnet is increased, shifting its operating point and reducing the risk of demagnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high coercivity and remanence magnets are used to increase torque production, then torque production is improved, but the cost increases and the magnets are more susceptible to demagnetization
Solution Approach 1:
The magnetic circuit is segmented into two distinct magnet types: a first magnet with high coercivity and a second magnet with high remanence. This segmentation allows each magnet to perform its specialized function - the first magnet protects against demagnetization while the second magnet provides high flux density for torque production.
Solution Approach 2:
The patent uses a composite magnetic circuit combining two different magnet materials with complementary properties. The first magnet (high coercivity) and second magnet (high remanence) work together in series to create a composite system that achieves both high torque and demagnetization resistance.
2Reliability
If high coercivity magnets are used to prevent demagnetization, then reliability is improved, but the cost increases
Solution Approach 1:
The magnetic circuit is divided into two magnet types with different functions. Only the first magnet (facing the air gap) uses high coercivity material for demagnetization resistance, while the second magnet uses lower-cost high remanence material, reducing overall cost while maintaining reliability.
Solution Approach 2:
High coercivity material is applied locally only where most needed - in the first magnet that directly faces the air gap and experiences the highest demagnetizing fields. The second magnet, protected by the first magnet, uses less expensive high remanence material.
3Ease of manufacture
If equal cross-sectional areas are used for both magnets, then manufacturing is simplified, but the operating point of the second magnet shifts to a lower flux density reducing torque production
Solution Approach 1:
The patent changes the geometric parameter (cross-sectional area) of the magnets to optimize performance. The first magnet has a smaller cross-sectional area than the second magnet, which increases the flux density in the second magnet and shifts its operating point to a more favorable position on the B-H curve for torque production.
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 reduces the risk of demagnetization of the second magnet while allowing for increased current in the conductors, resulting in higher torque production without the need for expensive high coercivity magnets.
Implementation Method 1
a first magnet with a first remanence value and a first coercivity value, the first magnet having a first cross-sectional area substantially normal to a direction of magnetization of the first magnet; and a second magnet positioned in series with the first magnet, the second magnet with a second remanence value and a second coercivity value that is less than the first coercivity value
Implementation Method 2
the second magnet is positioned in a path of the direction of magnetization of the first magnet
Implementation Method 3
A ratio of the first cross-sectional area to the second cross-sectional area is equal to or greater than a ratio of the second remanence value to the first remanence value
Implementation Method 4
Permanent magnets can be used to provide magnetic fields, which can be interacted with by current carrying conductors. The interaction can produce mechanical forces on the conductor and magnet assemblies, which forces can be harnessed for various applications such as, for example, motors
Data Source
AI summary
This disclosure provides systems, methods, and apparatus, including: a first magnet with a first remanence value and a first coercivity value, the first magnet having a first cross-sectional area substantially normal to a direction of magnetization of the first magnet; and a second magnet positioned in series with the first magnet, the second magnet with a second remanence value and a second coercivity value that is less than the first coercivity value, the second magnet having a second cross-sectional area substantially normal to a direction of magnetization of the second magnet. A ratio of the first cross-sectional area to the second cross-sectional area is equal to or greater than a ratio of the second remanence value to the first remanence value.