IPM Rotor Anisotropic Packets Torque Optimization
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Solution Overview
Problem
Interior permanent magnet electric machines rely heavily on magnetic material, which limits their efficiency and torque production due to high volumes of magnetic material required.
Innovation Solution
The use of a rotor assembly with steel laminations and anisotropic packets in specific slots within the rotor, optimizing the saliency ratio by increasing q-axis inductance while maintaining d-axis inductance, reduces the dependency on permanent magnets and enhances torque production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high volumes of magnetic material are used in interior permanent magnet machines, then torque production is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies local quality by using anisotropic magnetic material packets with specific grain orientation only in the slots where they are most effective for torque production, rather than using isotropic material throughout the entire rotor. This localized application of specialized material properties optimizes torque generation while reducing overall magnetic material volume and complexity.
Solution Approach 2:
The patent employs composite materials by combining isotropic magnetic material with anisotropic magnetic material packets in a hybrid rotor structure. The anisotropic packets are inserted into specific slots of the isotropic rotor, creating a composite magnetic circuit that leverages the advantages of both material types to improve torque density while reducing total magnetic material requirements.
2Power
If more permanent magnets are used, then torque per ampere increases, but weight and volume of the rotor increase
Solution Approach 1:
The patent changes the magnetic material parameters by introducing anisotropic material with specific grain orientation and magnetic properties into selected slots. This parameter change allows the magnetic circuit to achieve higher effective flux density and torque production in critical areas without proportionally increasing the total weight of magnetic material in the rotor.
3Reliability
If high volumes of magnetic material are used, then machine performance is improved, but manufacturing complexity and assembly difficulty increase
Solution Approach 1:
The patent segments the magnetic material into discrete anisotropic packets that are inserted into individual slots of the rotor. This segmentation allows for modular assembly where pre-fabricated packets can be independently positioned and secured in specific slots, simplifying the manufacturing process compared to assembling large monolithic magnetic structures while maintaining high performance.
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 improves rotor saliency, reduces magnet mass, and increases torque per ampere, efficiency, and high-speed performance, allowing for a more compact motor design with similar performance.
Implementation Method 1
plurality of packets assembled from anisotropic material are disposed in a second subset of the slots
Implementation Method 2
optimizing the saliency ratio by increasing q-axis inductance while maintaining d-axis inductance
Implementation Method 3
The stator generally includes a plurality of windings that produces electromagnetic poles of alternating polarity when excited with electrical current
Implementation Method 4
A plurality of permanent magnets are disposed in a first subset of the slots
Data Source
AI summary
An interior permanent magnet electric machine is described, and includes a stator including a plurality of electrical windings and a rotor disposed in a cylindrically-shaped void formed within the stator. The rotor includes a plurality of steel laminations assembled onto a shaft, wherein the shaft defines a longitudinal axis. Each of the steel laminations includes a plurality of poles and each of the poles includes a plurality of slots disposed near an outer periphery. The slots of the steel laminations are longitudinally aligned. A plurality of permanent magnets are disposed in a first subset of the slots, and plurality of packets assembled from anisotropic material are disposed in a second subset of the slots.