Stator Winding Segmentation for Inductance Balance
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Solution Overview
Problem
In rotating electric machines, the imbalance in inductance among different phases due to the disposition of stator windings in the same slot leads to inefficiencies, including varying current values, increased heat generation, and reduced power generating efficiency.
Innovation Solution
The stator winding is divided into multiple segments for each phase, ensuring balanced inductance by evenly distributing the coils within the slots, and connecting them in series or parallel to equalize inductance levels across phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If coils of different phases are disposed in the same slot with each phase in a biased condition, then the stator winding structure is simplified, but inductance imbalance occurs among the three phases
Solution Approach 1:
The patent divides each phase winding into multiple independent coil groups (e.g., U1, U2, U3 for U-phase; V1, V2, V3 for V-phase; W1, W2, W3 for W-phase) that are distributed across different slots. This segmentation allows each coil group to be positioned symmetrically, ensuring balanced inductance while maintaining structural simplicity through the modular arrangement.
2Loss of energy
If fractional-pitch winding is adopted with shorter coil length, then resistance is reduced and efficiency is improved, but inductance imbalance occurs when coils of different phases are disposed separately in inner and outer layers
Solution Approach 1:
The patent applies different radial positions (inner layer and outer layer) to different coil groups within the same phase, creating local variations in magnetic path length. By strategically assigning which coil groups are in inner layers and which are in outer layers, the patent achieves both shortened effective coil length for reduced resistance and balanced inductance through the localized quality distribution.
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 approach results in a rotating electric machine with balanced currents, reduced heat generation, and improved power generating efficiency by equalizing inductance among phases.
Implementation Method 1
a stator winding wound via an insulating sheet in the slots... Transform Mechanical Energy to Electrical Energy
Data Source
AI summary
An object is to provide a rotating electric machine offering a high output and high efficiency by balancing inductance of each phase even if a stator is used in which stator windings of different phases are disposed in a slot of a stator core in a three-phase winding. A stator 5 includes a stator core 6 having a plurality of slots arrayed circumferentially and opening to an inner peripheral surface and a stator winding 7 wound in each of the slots. The stator winding 7 is divided into at least two for each phase (7U-A, 7U-B, 7V-A, 7V-B, 7W-A, 7W-B). After insertion of the stator core 6, the stator winding of each phase is connected in parallel or in series. The stator winding of each phase is disposed in slots such that combined inductance of different phases is equalized.