Stator Core Teeth Asymmetry for Heat Dissipation and Cogging Torque
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Solution Overview
Problem
The existing stator designs for electric motors face a trade-off between coil heat dissipation and cogging torque, where improved heat dissipation often results in increased cogging torque, and vice versa.
Innovation Solution
A stator design featuring alternately arranged first and second core teeth with different cross-sectional shapes, where the second core teeth have a reduced width with a step or curved surface at the tip end, allowing the coil to contact both teeth for enhanced heat dissipation while approximating magnetic attraction forces to reduce cogging torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If core teeth with trapezoidal cross-section are alternately arranged with rectangular core teeth to improve heat dissipation, then coil heat dissipation is improved, but cogging torque increases
Solution Approach 1:
The core tooth width is made non-uniform along the axial direction, with the tip end portion having a different width than the base portion. This local variation in geometry allows the coil to contact the core tooth effectively for heat dissipation while controlling the magnetic attraction force to manage cogging torque
Solution Approach 2:
The core tooth cross-section transitions from a symmetric rectangular shape to an asymmetric shape with a step or curved surface at the tip end. This asymmetric design creates a non-uniform width distribution that optimizes both thermal contact and magnetic force characteristics
2Object-generated harmful factors
If the width of core teeth is reduced with a step or curved surface at the tip end to suppress cogging torque, then magnetic attraction force is approximated, but heat dissipation contact area is reduced
Solution Approach 1:
The solution moves from considering only the radial width of core teeth to incorporating the axial dimension by creating a step or curved surface at the tip end. This three-dimensional geometry modification allows the core tooth to maintain adequate width at the base for structural integrity and magnetic force control while providing sufficient contact area at the tip end for 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 improves coil heat dissipation while suppressing cogging torque, achieving a balance between the two by ensuring effective contact between the coil and core teeth and optimizing magnetic attraction forces.
Implementation Method 1
Part of the cooling of the coil 109 is performed by dissipating heat to the stator core 103 through the core teeth 105
Implementation Method 2
magnetic attraction force F2 received by the trapezoidal core tooth 106 from the permanent magnet 121 of the rotor 120
Data Source
AI summary
A stator of an electric motor has a cylinder-shaped stator core. First core teeth and second core teeth are alternately arranged in the circumferential direction on the inner peripheral surface of the stator core. The second core teeth each have a cross-sectional shape perpendicular to the central axis of the stator core different from the cross-sectional shape of the first core tooth. A coil is assembled to the first tooth. The coil is assembled to one of the first core tooth and the second core tooth. The width of the second core tooth is reduced with a step of a curved surface at a boundary between the tip end portion and a portion behind of the tip end portion.