Flux-Switching Motor Stator Segmentation for Mutual Inductance Reduction
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Solution Overview
Problem
Flux-switching magnetic machines lack sufficient fault-tolerance, leading to reduced performance and efficiency due to high mutual inductance between armature windings, which affects their reliability and smooth operation.
Innovation Solution
Increasing the number of fixed field members relative to armature windings and configuring the machine with multiple phases of armature windings to reduce mutual inductance and enhance fault-tolerance, while adjusting the number of turns and spacing of windings to optimize torque output and smooth motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of fixed field members is increased relative to armature windings, then fault-tolerance is enhanced and mutual inductance is reduced, but device complexity increases
Solution Approach 1:
The stator is segmented into more fixed field members (12) than armature windings (8), creating a segmented structure where each fixed field member acts as an independent magnetic pole. This segmentation reduces the coupling between adjacent armature windings by introducing intervening fixed field members that shield their magnetic fields, thereby reducing mutual inductance and enhancing fault-tolerance.
2Volume of moving object
If armature windings are spaced closer together to reduce machine size, then compactness is improved, but mutual inductance between windings increases
Solution Approach 1:
Intervening fixed field members are introduced as intermediary elements between adjacent armature windings. These fixed field members act as magnetic shields that reduce the direct magnetic coupling between neighboring windings. Even when windings are spaced closely for compactness, the intervening fixed field members maintain low mutual inductance by redirecting and shielding the magnetic flux paths.
3Power
If the number of armature windings is increased to improve torque output, then power is improved, but mutual inductance between windings increases
Solution Approach 1:
The stator exhibits local quality variation where different regions have different magnetic characteristics. By having more fixed field members than armature windings, each winding location experiences a unique local magnetic environment created by its adjacent fixed field members. This local differentiation reduces the uniformity of magnetic coupling across all windings, thereby reducing overall mutual inductance while maintaining sufficient torque output through optimized winding distribution.
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 solution significantly reduces mutual inductance between nearest neighbor armature windings, enhancing fault-tolerance, maintaining rated output during faults, and smoothing rotational motion by reducing torque ripple.
Implementation Method 1
The stator teeth each comprise a permanent magnet 22 magnetised such that the magnetisation polarities of the magnets alternate circumferentially around the stator 14
Implementation Method 2
As alternating current is passed through the three sets of armature windings, a variable magnetic field is generated that is superimposed over the fixed magnetic field resulting from the permanent magnets
Implementation Method 3
causing the rotor 12 to rotate within the stator 14 as it attempts to bring the rotor teeth 16 to a position of minimum reluctance with respect to the stator teeth 18
Data Source
AI summary
A flux-switching magnetic machine is provided having a drive element and a driven element. The drive element is configured to generate a composite magnetic field comprising a fixed component and a variable component, the fixed component being generated by spaced fixed field members and the variable component being generated by spaced armature windings. The driven element has a plurality of magnetisable portions configured to be coupled to the composite magnetic field generated by the drive element, such that the driven element moves in response to changes in this field. The number of fixed field members is greater than the number of armature windings.