Stator Segments with Lateral Cutouts for Harmonic Reduction
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Solution Overview
Problem
High-speed electric machines with annular stators and rotors face challenges in reducing rotor magnet losses due to high spatial harmonic content in the stator magnetic field, which leads to significant ohmic losses from eddy currents, and existing distributed windings require substantial space for end windings.
Innovation Solution
The electric machine features stator segments with lateral cutouts and toroidally applied windings, where the radial outer side of the winding is partially surrounded by stator segment outer arms, creating a radially directed outer gap that forms an additional magnetic circuit outside the stator, reducing the inductance coupled to the rotor and minimizing harmonic amplitudes of the stator magnetic field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a concentrated winding is used, then a compact design is possible, but high spatial harmonic content causes high ohmic losses in the rotor
Solution Approach 1:
The stator is divided into multiple stator segments in the circumferential direction, with each segment having lateral cutouts. This segmentation allows the stator winding to be arranged in a distributed pattern across segments while maintaining compact structure, thereby reducing spatial harmonics and rotor ohmic losses while preserving space efficiency
2Loss of energy
If a distributed winding is used, then eddy currents are significantly reduced, but a comparatively large amount of space is required for the end windings
Solution Approach 1:
The stator segments are arranged in the circumferential direction with lateral cutouts, creating a third dimensional arrangement for the windings. This allows distributed windings to be implemented with reduced end winding space by utilizing the circumferential dimension for winding distribution rather than extending windings axially
3Loss of energy
If the inductance coupled to the rotor is reduced, then rotor magnet losses are reduced, but the stator magnetic field strength may be weakened
Solution Approach 1:
The return conductors of the stator winding are extracted and arranged to run outside the stator in the circumferential direction, creating an additional inductance that is decoupled from the rotor. This allows the main stator magnetic field to remain strong for power generation while the external inductance provides harmonic filtering without weakening the primary magnetic field
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 keeps the stator magnetic field coupled to the rotor small, minimizing the influence of harmonic amplitudes on the rotor and allowing for efficient operation with reduced ohmic losses and compact design.
Implementation Method 1
the stator has a stator winding applied to a winding support, wherein each stator segment has lateral cutouts in the circumferential direction, a winding support having a toroidally applied stator winding is introduced into lateral cutouts
Implementation Method 2
This makes a compact design possible, but generates a stator magnetic field with a high spatial harmonic content. This in turn causes high ohmic losses in the rotor of the electric machine owing to eddy currents
Data Source
AI summary
An electric machine includes an annular stator and a rotor disposed within the stator. The stator has a plurality of stator segments in the circumferential direction and a stator winding applied to a winding support. Each stator segment has lateral cutouts in the circumferential direction. In each case a winding support having a toroidally applied stator winding is introduced into lateral cutouts, which are adjacent in the circumferential direction, of adjacent stator segments. The radial outer side of the stator winding is partially surrounded by stator segment outer arms of mutually adjacent stator segments in such a way that a radially directed outer gap is formed between the stator segment outer arms of the two mutually adjacent stator segments.