Dual-Layer Coreless Stator Coils for Lower AC Loss
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Solution Overview
Problem
Existing rotating electric machines with coreless coils in the stator suffer from significant AC losses in the coils due to interlinkage with the magnetic flux from the rotor, which hinders torque and voltage generation.
Innovation Solution
The stator structure comprises an inner and outer coil layer with coreless coils arranged circumferentially, where the inner coils are made of a material with higher electrical resistance, such as aluminum, and the outer coils are made of a lower resistance material like copper, with specific coil pitches and turns to optimize magnetic flux interlinkage and reduce AC losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If coreless coils are used in the stator, then weight is reduced, but AC loss increases due to magnetic flux interlinkage
Solution Approach 1:
The stator coil is divided into multiple independent winding sections (first, second, third, and fourth winding sections) arranged in different layers. Each section can be optimized independently for material selection and configuration, allowing reduction of AC loss through strategic segmentation while maintaining the coreless structure's weight advantage
Solution Approach 2:
Different winding sections use different conductor materials (e.g., aluminum for outer layers, copper for inner layers) based on their specific electromagnetic environment. This local differentiation optimizes the balance between weight and AC loss reduction in each specific region of the stator
2Ease of manufacture
If single-material coils are used, then manufacturing is simplified, but AC loss cannot be optimized
Solution Approach 1:
The patent applies different materials to different parts of the coil structure - for example, aluminum conductors in outer winding sections and copper conductors in inner winding sections. This allows each section to be optimized for its specific electromagnetic conditions while maintaining manageable manufacturing complexity through systematic material assignment
Solution Approach 2:
The coil structure combines multiple conductor materials (aluminum and copper) within a single coil assembly. This composite approach leverages the high conductivity of copper for inner sections and the lightweight properties of aluminum for outer sections, achieving both weight reduction and AC loss optimization
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 AC and DC losses in the stator coils, enhancing torque and voltage generation in electric motors and generators by optimizing the magnetic flux interlinkage and material resistance.
Implementation Method 1
a rotating magnetic field is generated by applying a voltage to a coil of the stator
Implementation Method 2
an electromotive force is induced on the rotor by the rotating magnetic field
Implementation Method 3
a voltage (electromotive force) is induced on a coil of the stator by a rotating magnetic field generated by rotation of the rotor
Implementation Method 4
a magnetic flux caused by the rotor interlinks with the coil of the stator
Data Source
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AI summary
In an embodiment, a stator structure in a rotating electric machine includes an inner coil layer and an outer coil layer. In the inner coil layer, a plurality of coreless inner coils are arranged side by side in a circumferential direction. In the outer coil layer, a plurality of coreless outer coils are arranged side by side in the circumferential direction on an outer peripheral side of the inner coil layer in a state not contacting the inner coils. Each coil winding of the inner coils is formed of a material different from that of each coil winding of the outer coils.