Spoke-Type Rotor Air Gaps for Flux Leakage Control
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Solution Overview
Problem
Current Vernier permanent magnet machines (VPPMs) face challenges with low power factor and increased manufacturing complexity due to additional harmonic flux leakage from permanent magnets, which also pose thermal issues and mechanical structural integrity concerns.
Innovation Solution
The design incorporates a rotor with alternating air gaps and permanent magnets mounted as spokes within the second rotor core, reducing flux leakage and manufacturing complexity while improving torque density and power factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If permanent magnets are added to the rotor to increase torque density, then torque production is improved, but power factor deteriorates due to additional harmonic flux leakage
Solution Approach 1:
The patent converts the harmful harmonic flux leakage into beneficial alternating air gaps. By strategically positioning non-magnetic air gaps between permanent magnets on the rotor, the design uses the same magnetic field interactions that cause harm to instead create controlled flux paths that reduce harmful leakage while maintaining torque production. The air gaps create alternating magnetic circuit paths that modulate the flux distribution.
Solution Approach 2:
The patent introduces air gaps as intermediary elements between permanent magnets. These air gaps act as mediators that control and shape the magnetic flux distribution, preventing direct harmful interactions between adjacent magnets while maintaining the overall magnetic circuit functionality. The air gaps serve as flux barriers that guide and organize the magnetic field patterns.
2Power
If a double rotor or dual stator structure is adopted to improve torque and power factor, then torque density and power factor are improved, but manufacturing complexity increases significantly
Solution Approach 1:
The patent segments the rotor structure by introducing discrete air gaps between permanent magnets rather than using a complex dual rotor or dual stator configuration. This segmentation approach divides the magnetic circuit into controlled sections, achieving the desired flux modulation and improved power factor while maintaining a single-rotor simple structure that is easier to manufacture.
Solution Approach 2:
The patent applies local quality changes by positioning air gaps at specific locations between permanent magnets on the rotor. Instead of fundamentally changing the overall machine structure to dual rotor/dual stator, the invention makes localized modifications to the rotor's magnetic circuit properties, creating alternating high and low permeability regions that improve performance without increasing manufacturing complexity.
3Power
If an additional layer of rotor or stator is introduced to improve torque density, then torque and power factor are enhanced, but thermal management becomes more difficult due to enclosed windings
Solution Approach 1:
The patent extracts the thermal management problem by avoiding the dual rotor/dual stator configuration that would enclose windings and trap heat. Instead, the invention achieves improved torque density and power factor through rotor-only modifications with air gaps, maintaining an open thermal path and avoiding the creation of enclosed spaces that would hinder heat dissipation.
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 design enhances torque production and power factor, reduces manufacturing complexity, and addresses thermal issues, making it suitable for low and medium speed applications as both a motor and generator.
Implementation Method 1
The plurality of permanent magnets are mounted as spokes in pole pairs within the second rotor core
Implementation Method 2
A plurality of rotor air gaps are formed in the first rotor core between a rib of the plurality of ribs and a tooth of the plurality of rotor core teeth
Data Source
AI summary
The rotor includes ribs and permanent magnets mounted as spokes in pole pairs. A second wall of each rotor air gap of a plurality of rotor air gaps is parallel to an edge of a permanent magnet of the permanent magnets. A length of the second wall is less than 80% of a length of the edge. A fifth wall of each rotor air gap of the rotor air gaps is formed by a first side of a rib. Each pair of permanent magnets has an associated pair of rotor air gaps of the rotor air gaps. A first rotor air gap of each pair of rotor air gaps of the rotor air gaps is a mirror image of a second rotor air gap of each pair of rotor air gaps. Each pair of rotor air gaps is separated by an associated rib of the plurality of ribs.