Radially Embedded Permanent Magnet Rotor Design
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Solution Overview
Problem
The increasing cost of rare earth magnets and copper used in electric motors necessitates the development of lower-cost alternative materials that maintain efficiency and power density, while also reducing the length of the motor to avoid material cost and application constraints.
Innovation Solution
The design incorporates a radially embedded permanent magnet rotor with radial apertures and independent pole pieces, using lower-cost magnets and minimizing the use of copper windings by optimizing the flux generation and torque production, and employing non-magnetic materials to reduce flux losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If rare earth permanent magnets are used to generate greater amounts of flux, then the flux generation and torque production are improved, but the material cost drastically increases
Solution Approach 1:
The patent changes the parameters of the magnet arrangement by embedding permanent magnets radially within the rotor core rather than placing them on the surface. This radial embedding configuration optimizes the magnetic circuit path and flux distribution, allowing lower-cost ferrite magnets to achieve flux generation levels comparable to expensive rare earth magnets while reducing material costs significantly.
Solution Approach 2:
The patent employs composite construction by combining ferrite permanent magnets with a magnetically soft rotor core material. This composite approach allows the system to achieve high flux generation through optimized magnetic circuit design rather than relying on expensive rare earth magnet materials alone, thus reducing material costs while maintaining power output.
2Adaptability or versatility
If the motor length is reduced to address application constraints, then the application adaptability is improved, but the efficiency and power density may deteriorate
Solution Approach 1:
The patent transitions from conventional axial magnet placement to radial magnet embedding within the rotor core. This dimensional change in magnet arrangement allows for more efficient use of the rotor volume, generating higher flux density in a compact radial space. This enables the motor to maintain high power density in a shorter length, satisfying application constraints without sacrificing performance.
Solution Approach 2:
The patent optimizes magnetic circuit parameters by embedding magnets radially at specific depths and angles within the rotor core. This parameter optimization increases the magnetic flux density and improves the magnetic coupling between rotor and stator, enabling high power density in a compact motor length that meets application constraints.
3Quantity of substance
If copper windings are minimized to reduce material cost, then the material cost is reduced, but the torque production and efficiency may worsen
Solution Approach 1:
The patent changes the magnetic field generation approach by using permanently magnetized rotor poles instead of electromagnets requiring copper windings. This parameter change eliminates the need for field winding copper, significantly reducing copper material usage while maintaining strong magnetic fields for torque production through the permanent magnets embedded in the rotor core.
Solution Approach 2:
The patent extracts and removes the copper field windings from the rotor structure, replacing them with permanent magnets. This extraction eliminates the copper material requirement for field generation while concentrating the magnetic field production function in the permanent magnets, thereby reducing material cost without compromising torque production capability.
4Manufacturing precision
If adhesive is used to secure magnets in slots, then the magnet positioning is improved, but the reliability deteriorates due to limited adhesive life from temperature and environmental factors
Solution Approach 1:
The patent replaces the chemical bonding system (adhesive) with a mechanical retention system. The permanent magnets are embedded in radially oriented slots within the rotor core and retained by mechanical features such as retaining rings, interference fits, or mechanical clips. This mechanical substitution eliminates adhesive degradation from temperature and environmental exposure while maintaining precise magnet positioning through mechanical constraints.
Solution Approach 2:
The patent introduces mechanical retaining structures as intermediaries between the permanent magnets and the rotor core. These retaining features (such as retaining rings or interference fit structures) serve as mediators that securely hold the magnets in precise positions without relying on temperature-sensitive adhesives, thereby improving reliability in harsh thermal and environmental conditions.
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 approach achieves increased efficiency and power density comparable to systems using rare earth magnets, while reducing material costs and motor length, thus addressing the challenges of rising material costs and application constraints.
Implementation Method 1
Some known rare earth permanent magnets, such as neodymium iron boron magnets, generate greater amounts of flux than typical ferrite permanent magnets
Implementation Method 2
Many known electric machines produce work by generating torque, which is the product of flux, stator current and other constants
Data Source
AI summary
In one embodiment, a permanent magnet rotor for use with a stator is provided. The permanent magnet rotor includes at least one permanent magnet and a substantially cylindrical rotor core including an outer edge, a hub having an inner edge defining a central opening, and a plurality of independent pole pieces spaced from the hub radially about the central opening. The rotor core further includes at least one radial aperture extending radially from the outer edge through the rotor core between adjacent independent pole pieces, the at least one aperture configured to receive the at least one permanent magnet.