Stator Winding Segmentation for Electrical Balance
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Solution Overview
Problem
Existing rotating electric machines face challenges in achieving electrical balance between parallel-connected sub-windings of the stator coil, leading to circulating currents and increased electrical losses.
Innovation Solution
The stator design includes an annular stator core with a three-phase stator coil, where each phase winding is composed of multiple sub-windings connected in parallel, with in-slot portions arranged in K layers across M slots, ensuring even distribution and electrical connection between sub-windings, and the number of magnetic poles is set to a multiple of the number of sub-windings, promoting electrical balance and minimizing circulating currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the number of sub-windings is increased to reduce AC copper loss, then electrical loss is reduced, but it becomes difficult to achieve electrical balance between parallel-connected sub-windings, leading to circulating current and increased electrical loss
Solution Approach 1:
The phase windings are divided into multiple sub-windings (L sub-windings where L is an odd number greater than or equal to 3) that are connected in parallel. Each sub-winding is further segmented into in-slot portions arranged in K layers (where K is an even number) across M slots. This segmentation allows for balanced distribution of current paths while maintaining electrical balance between parallel sub-windings.
Solution Approach 2:
The in-slot portions of each sub-winding are selectively arranged in specific slots with specific layer configurations. The Nth layer in one slot is electrically connected with the (N+1)th layer in another slot, creating localized electrical balance at each connection point. This local quality control ensures that circulating currents are prevented while maintaining overall electrical balance.
2Power
If sub-windings are connected in parallel to reduce AC copper loss, then power loss is reduced, but circulating current may be generated due to electrical imbalance, increasing electrical loss
Solution Approach 1:
The electrical connection between the Nth layer in one slot and the (N+1)th layer in another slot creates equipotential connections between parallel sub-windings. This equipotential arrangement ensures that all parallel-connected sub-windings have equal electrical potential, preventing circulating currents from generating while maintaining the power reduction benefits of parallel connection.
Solution Approach 2:
The patent specifies that K (number of layers) must be an even number, M (slots per pole per phase) must be a natural number greater than or equal to 2, and L (number of sub-windings) must be an odd number greater than or equal to 3. These parameter constraints ensure proper electrical balance and prevent circulating currents while achieving reduced AC copper loss through parallel sub-winding configuration.
3Reliability
If in-slot portions are arranged in multiple layers across slots, then electrical balance is achieved, but device complexity increases
Solution Approach 1:
The winding structure is designed with universal applicability where the same arrangement pattern of in-slot portions in K layers across M slots can be applied to all L sub-windings. This multi-functional design allows the same structural template to achieve electrical balance for all parallel-connected sub-windings simultaneously, reducing overall device complexity while maintaining electrical balance.
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 achieves electrical balance between sub-windings, preventing circulating currents and minimizing electrical losses in the rotating electric machine, while ensuring equal phase resistances and efficient operation.
Implementation Method 1
The stator coil is comprised of three phase windings that are mounted on the stator core so as to be different in electrical phase from each other. Each of the phase windings includes a plurality of in-slot portions each of which is received in one of the slots of the stator core.
Data Source
AI summary
A stator includes a stator core having slots and a stator coil comprised of three star-connected phase windings. In each of the slots, there are arranged in-slot portions of the phase windings in six layers. Each of the phase windings is comprised of five parallel-connected sub-windings. At each of the six layers, the in-slot portions of the sub-windings are arranged in a plurality of slot pairs; the slot pairs are circumferentially spaced from one another and each consist of two consecutive slots that are respectively identified as types A and B of the slots. Moreover, for each of the sub-windings, the in-slot portions of the sub-winding are evenly distributed to the two types A and B so that the number of the in-slot portions of the sub-winding arranged in the slots of the same type at each of the six layers is equal to 2.