Variable Thickness Magnetic Layers in Stator Coils
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Solution Overview
Problem
In rotary electric machines, the leakage flux between stator teeth generates eddy currents, leading to increased losses, and existing solutions that reduce eddy currents by facilitating leakage flux to magnetic plates result in a decreased conductor space factor due to uniform magnetic plate thickness.
Innovation Solution
A stator design with magnetic layers of varying thickness between coil bodies, thicker closer to the rotor, inhibits leakage flux from flowing through the coil, preventing eddy current generation while maintaining the conductor space factor by arranging magnetic layers according to the leakage flux distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a magnetic plate with constant thickness is inserted between coil wires to reduce eddy current, then eddy current is reduced, but the conductor space factor decreases
Solution Approach 1:
The magnetic plate thickness is made variable rather than constant, with greater thickness at the tooth tip end (where leakage flux is highest) and smaller thickness at the root end (where leakage flux is lowest). This local variation in thickness optimizes eddy current reduction where needed while preserving conductor space where less protection is required.
Solution Approach 2:
The thickness parameter of the magnetic plate is changed from a constant value to a variable value that depends on position along the tooth height. This parameter change allows the magnetic plate to adapt to the non-uniform distribution of leakage flux, reducing eddy current loss effectively while minimizing impact on conductor space factor.
2Loss of energy
If magnetic plate thickness is increased to better block leakage flux, then eddy current reduction improves, but conductor space factor decreases
Solution Approach 1:
Instead of uniformly increasing magnetic plate thickness throughout, the invention applies greater thickness only at the tooth tip end where leakage flux and eddy current are most severe, while maintaining smaller thickness at the root end. This localized approach provides effective eddy current reduction without unnecessarily reducing conductor space.
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
Effectively reduces eddy current losses by directing leakage flux through magnetic layers, maintaining the conductor space factor by varying the magnetic layer thickness based on flux distribution, thereby enhancing efficiency and performance.
Implementation Method 1
leakage flux between the teeth is able to be inhibited from flowing through the coil bodies, by flowing through the magnetic body
Implementation Method 2
an eddy current is able to be inhibited from being generated in the coil bodies
Data Source
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AI summary
A stator (12) of a rotary electric machine includes a stator core (21), coils (22) and magnetic bodies (44). The stator core (21) comprises a plurality of teeth (23) protruding towards the rotor and being spaced apart from each other and a plurality of slots (24) arranged between two adjacent teeth (23). The coils (22) are formed out of coil bodies (42) being stacked in radial direction, thus the direction into which the teeth are extending, and are wound inside of slots (24) around the teeth (23). The magnetic bodies (44) are arranged between adjacent coil bodies (42). The thickness of the magnetic bodies (44) in radial direction increases with increasing length of the tooth (23) or with decreasing distance towards the air gap between rotor (14) and stator (12).