Fractional Slot Multi Winding Electrical Machine Segmentation
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Solution Overview
Problem
Fractional slot dual three-phase winding set electrical machines face issues with parasitic air gap sub-harmonic frequencies, reduced cooling surface area, and increased susceptibility to demagnetization during fault conditions compared to integer slot distributed winding topologies.
Innovation Solution
The electrical machine is segmented into multiple sections with a dual three-phase winding set configuration, featuring a high number of slots and poles, and a concentrated winding scheme with a star connection point, along with a cooling system that increases the cooling surface area, and a method to phase shift currents between winding sets to reduce harmonics and demagnetization risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If fractional slot concentrated winding topology is used, then electromagnetic performance is improved, but cooling surface area is reduced
Solution Approach 1:
The stator is divided into multiple independent modules (e.g., 3 modules with 4 slots each for a 12-slot machine), allowing the winding structure to be segmented while maintaining concentrated winding benefits. This modular segmentation increases the end-winding surface area exposed to cooling media, thereby improving the cooling surface area without compromising electromagnetic performance
2Power
If fractional slot concentrated winding topology is used, then electromagnetic performance is improved, but susceptibility to demagnetization during fault conditions increases
Solution Approach 1:
The winding set is divided into multiple independent modules where each module has its own winding connections. During fault conditions such as short-circuits, this segmentation limits the fault current propagation to individual modules rather than affecting the entire winding set, thereby reducing the demagnetization risk to permanent magnets while maintaining electromagnetic performance
Solution Approach 2:
The patent employs specific slot and pole number combinations (e.g., 12 slots/10 poles, 12 slots/14 poles) that optimize the electromagnetic performance while controlling the harmonic content and fault current characteristics, thereby reducing demagnetization susceptibility
3Device complexity
If fractional slot topology is used, then winding compactness is improved, but parasitic air gap sub-harmonic frequencies increase
Solution Approach 1:
By segmenting the stator into multiple modules with specific slot distributions, the patent modifies the spatial harmonics generated by the concentrated winding. This segmentation helps to distribute and reduce the amplitude of parasitic air gap sub-harmonic frequencies while maintaining the compactness advantage of concentrated windings
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 effectively reduces parasitic air gap sub-harmonic frequencies, improves cooling efficiency, and decreases the risk of demagnetization, while enhancing generator performance and reducing costs through increased cooling surface area and modular design.
Implementation Method 1
a cooling system which increases the cooling surface area
Implementation Method 2
the electrical machine may be configured as a generator for generating electrical energy
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
It is described a fractional slot multi winding set electrical machine (150), comprising: at least one sections (100) forming a whole circumference in a circumferential direction (103), each section having a stator portion (102) and a rotor portion (104), the stator portion of each section comprising: a number of slots (105) alternating with teeth (107) along the circumferential direction; a first winding set (125); at least one second winding set (127), wherein the first and second winding sets (125, 127) are arranged at least partly in the slots (105), in particular according to a concentrated winding topology, the rotor portion (104) of each section comprising: a number of poles (122) of plural magnets (121) separated by a gap (g) from the teeth (107).