Electric Rotating Machine Housing Insulation for Eddy Current Suppression
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Solution Overview
Problem
Conventional electric rotating machines experience efficiency losses due to eddy currents generated by leakage flux near the inner surface of the housing, which can reduce torque and cooling performance, especially when the gap between the stator and rotor elements is small, and existing solutions either increase the machine's size or compromise on magnetic shielding, cooling, and mechanical strength.
Innovation Solution
The implementation of electric insulating portions on the inner surface of the housing, which can be formed using electric insulation films or agents, helps to suppress eddy currents even with a reduced gap between the stator and rotor elements, thereby improving torque characteristics and reducing the machine's size without compromising on other essential requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the gap between stator and rotor elements is reduced to improve torque density and compactness, then machine size and weight are reduced, but eddy currents are generated in the housing due to leakage flux
Solution Approach 1:
An electric insulating portion is introduced as an intermediary element between the housing and the magnetic components (stator/rotor). This insulating layer blocks the path of leakage flux through the housing, preventing eddy current generation while allowing the gap to remain small for compact design
Solution Approach 2:
The electric insulating portion is applied locally at specific positions where leakage flux intersects the housing (such as near the inner surface of the housing), rather than requiring a complete redesign of the entire housing structure. This targeted approach prevents eddy currents without adding unnecessary weight or complexity
2Ease of manufacture
If conventional structures are used without electric insulating portions, then manufacturing is simpler, but eddy currents reduce torque and cooling performance
Solution Approach 1:
The electrical parameter of the housing is changed by adding an insulating layer, transforming it from a conductive structure susceptible to eddy currents into an electrically insulated structure. This parameter change prevents torque reduction while maintaining manufacturing simplicity through the use of conventional insulation materials and methods
3Length of stationary object
If the housing is designed for compactness with reduced gaps, then machine dimensions are minimized, but magnetic shielding and cooling requirements are compromised
Solution Approach 1:
The housing structure is segmented into functional zones: the main housing body maintains compact dimensions, while electric insulating portions are added at critical locations where magnetic shielding is needed. This segmentation allows compact overall dimensions while providing localized magnetic shielding where required
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 solution effectively suppresses eddy currents, enhancing the rotation performance and torque characteristics of electric rotating machines while maintaining a compact size and meeting requirements for protection, magnetic shielding, and cooling, making them suitable for high-torque and high-output applications.
Implementation Method 1
an eddy current formed by a leakage flux is generated near the inner surface of the housing
Implementation Method 2
an eddy current formed by a leakage flux is generated near the inner surface of the housing
Implementation Method 3
The housing is provided with an electric insulating portion on a part of or whole of an inner surface including a surface facing at least one of the stator element and the rotor element
Data Source
AI summary
An electric rotating machine according to an embodiment includes a stator element, a rotor element, and a housing. The rotor element is rotatable about a rotation axis. The housing houses the stator element and the rotor element, and is provided with an electric insulating portion on a part of or whole of an inner surface including a surface facing at least one of the stator element and the rotor element.