Stator Winding Transposition for Equalizing Current Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In electric machines with stators where individual wires are arranged one above the other in grooves, varying radial distances from the rotor lead to different induced voltages and equalizing currents, causing inefficiencies and potential damage.
Innovation Solution
The stator design ensures an equal average radial distance for all individual wires by arranging coil sections in grooves such that they are either parallel or staggered, and incorporating transposition areas where the strand is turned 180°, preventing equalizing currents and ensuring uniform voltage induction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If individual wires are arranged one above the other in the grooves of the stator, then the winding structure is simple and easy to manufacture, but different radial distances from the rotor cause different induced voltages leading to equalizing currents and energy losses
Solution Approach 1:
The strand is divided into multiple individual wires that are arranged in a specific transposed sequence within the grooves. This segmentation allows each wire to experience different radial positions during rotation, equalizing the induced voltages across all wires and eliminating equalizing currents while maintaining the simplicity of the winding structure.
Solution Approach 2:
The individual wires are arranged in a periodic transposed pattern within the grooves, where the sequence of wires changes at regular intervals along the strand length. This periodic arrangement ensures that over one complete rotation of the rotor, each wire experiences equivalent average radial distances, equalizing the induced voltages and preventing energy losses from equalizing currents.
2Ease of manufacture
If individual wires are arranged one above the other in the grooves of the stator, then the winding structure is simple, but the unequal flux densities at different radial positions cause circulating currents that can damage the motor winding
Solution Approach 1:
The strand is segmented into multiple individual wires arranged in a transposed configuration within the grooves. This segmentation ensures that no single wire is permanently positioned at a disadvantageous radial location, distributing the electromagnetic stress evenly across all wires and preventing localized overheating or damage that would compromise winding reliability.
Solution Approach 2:
The periodic transposition of individual wires within the grooves ensures that over one complete rotor rotation, each wire experiences equivalent exposure to varying flux densities. This periodic arrangement prevents circulating currents and protects the motor winding from damage while maintaining manufacturing simplicity.
3Loss of energy
If Roebel bars with rectangular cross-section wires are used to prevent equalizing currents, then energy losses are reduced, but the device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
Instead of changing the wire cross-section shape to rectangular as in Roebel bars, this invention maintains round wire cross-sections and instead changes the arrangement parameters - specifically the transposed sequence and positioning of individual wires within the grooves. This parameter change achieves the same functional result of eliminating equalizing currents while preserving the manufacturing advantages of round wires.
Solution Approach 2:
Rather than modifying the wire shape (as in Roebel bars), this invention inverts the approach by modifying the arrangement and positioning of standard round wires within the grooves. The transposed arrangement of individual wires achieves equal voltage induction without requiring complex rectangular cross-section construction, thereby reducing device complexity while maintaining energy efficiency.
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 arrangement reduces losses and prevents damage from equalizing currents, ensuring reliable operation by maintaining uniform voltage across all wires, thereby enhancing efficiency and longevity.
Implementation Method 1
When the rotor is moved relative to the stator during operation of the electric machine it is the case that, with increasing feed frequency and/or increasing feed current, different voltages are induced into the individual wires
Data Source
AI summary
A stator for an electric machine includes a stator carrier having a plurality of grooves with a respective groove base, and a motor winding having at least one first strand. A predetermined number of first grooves of the plurality of grooves is associated with the first strand. At least one coil section of the first strand is introduced into each of the first grooves. The first strand has a plurality of individual wires connected electrically in parallel, with each wire formed as a round wire. At least some of the individual wires in each of the coil sections are arranged above one another in a radial direction of the stator. The coil sections are each arranged in the first grooves in such a way that an average radial distance of the individual wires to the groove base is equal for all individual wires.