Stator Phase Shift Windings for Electric Machine Skin Effect Reduction
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Solution Overview
Problem
There is a growing demand for electric machines with reduced size and increased efficiency, particularly in vehicle applications, where existing designs struggle to meet the requirements of cost-efficient manufacturing and stringent performance demands.
Innovation Solution
The design incorporates a stator with a phase shift winding pattern that includes multiple phases with parallel windings, where each winding fills central and outer slots in a specific ratio, and phase shift end loops adjust the pitch to optimize slot filling and reduce the skin effect, allowing for a compact and efficient electric machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional winding patterns are used, then manufacturing is simpler, but skin effect increases and efficiency decreases
Solution Approach 1:
The winding pattern is segmented into multiple parallel windings (first and second parallel windings) with different slot filling configurations. Each winding fills a specific number of slots (e.g., first winding fills 7 slots, second winding fills 9 slots), creating distinct segments that collectively reduce skin effect while maintaining manufacturability through modular assembly
Solution Approach 2:
Different regions of the stator core receive different winding configurations. Central slots and outer slots are filled with different numbers of windings (e.g., central slots receive 2 windings, outer slots receive 1 winding), creating local quality variations that optimize current distribution and reduce skin effect in specific high-current-density regions
2Reliability
If slot fill ratio is increased to improve efficiency, then electrical balance improves, but manufacturing complexity increases
Solution Approach 1:
The winding assembly is divided into multiple independent parallel windings that can be manufactured and positioned separately. Each winding is inserted into predetermined slots with specific fill ratios (e.g., 2:1 in central slots, 1:1 in outer slots), allowing for standardized manufacturing processes while achieving overall electrical balance through the segmented configuration
Solution Approach 2:
Windings are pre-configured with specific slot fill patterns before final assembly. The number of turns and slot positions are predetermined (e.g., first winding with 7 slots, second winding with 9 slots), allowing for preliminary quality control and ease of assembly during final installation into the stator core
3Volume of moving object
If machine size is reduced to meet vehicle application requirements, then compactness improves, but cooling capability deteriorates
Solution Approach 1:
The winding configuration utilizes both central slots and outer slots in a three-dimensional arrangement around the stator core. This spatial distribution across multiple dimensions (radial, circumferential, and axial positions) allows for compact machine design while maintaining adequate thermal pathways through the distributed winding structure that facilitates heat dissipation in multiple directions
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 results in a cost-efficient, compact, and efficient electric machine with improved electrical balance and reduced skin effect, addressing the challenges of size and efficiency while maintaining manufacturability.
Implementation Method 1
each wire includes a phase shift end loop having a pitch that differs from the standard pitch by one slot; each of the parallel windings having the phase shift end loop at the same pole locations whereby the phase shift end loops shift the parallel windings from one of the outer slots to the other outer slot
Data Source
AI summary
A multi-phase electric machine having plurality of windings are mounted on the stator core that define a plurality of phases wherein, for each phase, the windings include at least two parallel windings, each winding comprising a pair of continuous wires. For each pole, the parallel windings fill one or more central slots and two outer slots. Each winding fills each central slot twice the number of times that the winding fills each outer slot to thereby define a slot fill ratio of 2:1 between central slots and outer slots and wherein each wire of the wire pair forming a winding fills the slots in a ratio that differs from the slot fill ratio. Each of the parallel windings includes a phase shift end loop that shift the windings from one outer slot to the other outer slot.