Stator Core Slot Opening Layout for Lower Cogging Torque
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Solution Overview
Problem
Existing electric machine stators with hairpin windings face challenges in reducing cogging torques due to the difficulty in skewing the stator winding, which is essential for minimizing torque ripple.
Innovation Solution
A stator core design that emulates a skewed structure by varying the relative angular positions of slot openings along the axial direction, allowing for a modified rotating field that reduces cogging torques without requiring actual skewing of the stator or rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the stator is skewed to reduce cogging torques, then torque ripple is reduced, but the manufacturing complexity increases and hairpin windings cannot be easily used
Solution Approach 1:
The patent applies local quality by varying the angular position of slot openings specifically at the radial position between the receiving portion and rotor receiving space, while keeping the receiving portions parallel along the axial direction. This localized angular variation emulates the skewing effect to reduce cogging torques without requiring actual skewing of the entire stator structure, thus maintaining manufacturing simplicity and compatibility with hairpin windings.
2Object-affected harmful factors
If the stator is skewed to reduce torque ripple, then torque ripple is reduced, but the ease of manufacture deteriorates
Solution Approach 1:
The invention implements local quality by maintaining parallel receiving portions along the axial direction while introducing angular variation only in the slot openings at a specific radial position. This allows hairpin windings to be easily installed in the parallel receiving portions while the slot opening angular variation provides the torque ripple reduction effect, thus resolving the contradiction between ease of manufacture and torque ripple reduction.
3Object-affected harmful factors
If the relative angular positions of slot openings are varied along the axial direction to emulate skewing, then cogging torques are reduced, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the angular position parameter of slot openings specifically at the radial position between the receiving portion and rotor receiving space. This targeted parameter variation emulates the skewing effect to reduce cogging torques without changing the overall parallel structure of the stator, thus achieving torque optimization with minimal increase in device complexity.
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 effectively minimizes cogging torques and torque ripple, optimizing the magnetic flux distribution and reducing manufacturing complexity by allowing the use of hairpin windings in electric machines.
Implementation Method 1
The invention is based on the concept of emulating the effect of a skewed stator core, in which the relative angular position of the entire slot changes along the axial direction, by changing the relative angular positions of the slot opening along the axial direction. As a result, it is possible to modify a rotating field of a stator formed from the stator core according to the invention
Data Source
AI summary
A stator core for a stator of an electric machine includes a rotor receiving space which traverses the stator core along an axial direction; and several of slots which, in the circumferential direction, are formed successively in the stator core. The slots traverse the stator core axially from a first end side to an opposite second end side of the stator core. The slots have respectively a receiving portion in which a stator winding of the stator is able to be received, and a slot opening which is formed at a radial position between the receiving portion and the rotor receiving space and in terms of the receiving portion has relative angular positions which are mutually offset along the axial direction.