Asymmetric Trapezoidal Stator Tooth Heads for Lower Flux Leakage
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Solution Overview
Problem
Existing stators for electrical machines face inefficiencies in reducing current heat losses and magnetic flux leakage, while also compromising acoustic performance and torque stability due to conventional tooth head designs.
Innovation Solution
The stator features trapezoidal tooth heads arranged asymmetrically, with two projections forming a step, reducing effective tooth width and leakage flux, and made from magnetically conductive material for enhanced performance and acoustic behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional tooth head designs are used, then manufacturing is simpler, but current heat losses and magnetic flux leakage increase
Solution Approach 1:
The tooth head is designed with an asymmetric trapezoidal cross-section where the two legs have different lengths. This asymmetric geometry creates different air gap lengths on either side of the tooth tip, which reduces the magnetic stray flux and current heat losses in the electrical conductor resting against the tooth tip, while maintaining manufacturability through standard stamping processes
Solution Approach 2:
The tooth head geometry is optimized locally at the tooth tip region with a trapezoidal cross-section featuring different leg lengths. This local geometric modification specifically targets the reduction of current heat losses and magnetic flux leakage at the tooth tip area, while the rest of the stator structure remains conventional for ease of manufacture
2Loss of energy
If conventional tooth head designs are used, then structure is simpler, but magnetic stray flux losses increase
Solution Approach 1:
The asymmetric trapezoidal tooth head design with unequal leg lengths creates favorable magnetic flux distribution by reducing the effective air gap on one side, thereby minimizing magnetic stray flux losses between tooth tips while maintaining structural simplicity through integral construction
Solution Approach 2:
The tooth head geometry parameters are specifically optimized with a trapezoidal cross-section where the leg length ratio and base dimensions are tailored to reduce magnetic stray flux. This parameter optimization achieves lower magnetic losses without requiring complex multi-component structures
3Ease of operation
If symmetric tooth tips are used, then acoustic performance is acceptable, but torque ripple is higher
Solution Approach 1:
The asymmetric tooth head design with different leg lengths creates unequal air gaps that modify the magnetic field distribution in the air gap region. This asymmetric magnetic field distribution reduces torque ripple by smoothing out the torque pulsations, while the acoustic performance is optimized through the specific geometric proportions of the trapezoidal shape
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 minimizes current heat losses, magnetic leakage, and torque ripple, while improving acoustic properties and reducing manufacturing costs, achieving higher performance and lower noise levels in electrical machines.
Implementation Method 1
losses due to magnetic stray flux between the tooth tips are reduced
Implementation Method 2
current heat losses in the electrical conductor of a stator winding that rests against the tooth tip
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a stator (1) of an electric machine (10), which stator has a stator yoke (2) that extends annularly around a stator axis (400) and has stator teeth (3) that each extend along a tooth axis and protrude from the stator yoke (2) in the radial direction relative to the stator axis (400), wherein a first end (5) of each stator tooth (3) is arranged on the stator yoke (2) and a tooth head (4) is formed on a second end (6) opposite the first end (5), each tooth head having two tooth-head projections (X, Y), each of which projects transversely to the tooth axis with respect to the remaining stator tooth (3) so as to form a tooth-head step, characterised in that each tooth head (4) of the stator teeth is trapezoidal and is formed asymmetrically with respect to the particular tooth axis.