Rotating Electrical Machine Double Air Gap Flux Switching
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Solution Overview
Problem
Rotating electric machines with high power-to-weight ratios face structural and mechanical challenges, particularly in aerospace applications, due to magnetic attraction forces leading to unpredictable failures from gyroscopic moments and the need for heavy mechanical structures.
Innovation Solution
A rotating electric machine with a double air gap configuration, featuring a tubular rotor with alternating ferromagnetic and non-magnetic materials, and stators with Halbach arrays, allowing for flux switching and eliminating external bending moments, thus simplifying the mechanical structure while maintaining electromagnetic advantages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a double rotor configuration is used to achieve high magnetic flux density and optimal magnetic circuit utilization, then electromagnetic efficiency is improved, but mechanical complexity and weight increase
Solution Approach 1:
The invention extracts the flux-guiding function from the rotor and transfers it to the stator. The stator now contains both the coils and the flux-guiding material, while the rotor is simplified to contain only magnets. This separation eliminates the complex mechanical structure of double rotors while maintaining electromagnetic efficiency.
Solution Approach 2:
The invention inverts the conventional arrangement by placing flux-guiding material in the stator instead of the rotor. This reversal allows the stator to perform dual functions (electromagnetic excitation and flux guidance) while the rotor is simplified to a lighter construction with magnets only.
2Loss of energy
If oriented magnets (Halbach arrays) are used on both sides to achieve radially homogeneous magnetic flux density, then electromagnetic performance is improved, but stator weight increases or copper usage must be reduced
Solution Approach 1:
The stator is designed to perform multiple functions: it provides electromagnetic excitation through coils and simultaneously serves as the flux-guiding structure. This multi-functionality eliminates the need for separate flux-guiding rotors and reduces overall machine weight while maintaining electromagnetic efficiency.
3Power
If a bell rotor configuration is used to achieve double air gap, then electromagnetic advantages are obtained, but high bending moments require heavy mechanical structure
Solution Approach 1:
The invention extracts the flux-guiding function from the rotor and transfers it to the stator. The stator now contains both the coils and the flux-guiding material, while the rotor is simplified to contain only magnets. This separation eliminates the complex mechanical structure of double rotors while maintaining electromagnetic efficiency.
Solution Approach 2:
The invention inverts the conventional arrangement by placing flux-guiding material in the stator instead of the rotor. This reversal allows the stator to perform dual functions (electromagnetic excitation and flux guidance) while the rotor is simplified to a lighter construction with magnets only.
4Power
If conventional double rotor design is used to achieve high power density, then electromagnetic efficiency is improved, but rotor dynamics reliability deteriorates under gyroscopic moments
Solution Approach 1:
The invention extracts the flux-guiding function from the rotor and transfers it to the stator. The stator now contains both the coils and the flux-guiding material, while the rotor is simplified to contain only magnets. This separation eliminates the complex mechanical structure of double rotors while maintaining electromagnetic efficiency.
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 a 30-40% power-to-weight advantage and potentially over 100% higher power density, enabling applications like electric flight and improving sectors like wind turbines by eliminating mechanical constraints and enhancing magnet cooling.
Implementation Method 1
Using oriented magnets (e.g., Halbach arrays) on both sides, the magnetic flux density is configured so as to be radially highly homogeneous
Implementation Method 2
The magnets may be formed as Halbach arrays. A Halbach array is a special arrangement of permanent magnets. Such an arrangement makes it possible for the magnetic flux to be virtually canceled out at one side of the arrangement, whereas the magnetic flux is amplified to a maximum extent on the other side
Implementation Method 3
the rotor being formed from a ferromagnetic but non-magnetized material. It is thus made possible to conduct the magnetic flux but also interrupt the magnetic flux again (e.g., flux switching)
Implementation Method 4
coils, in which a voltage is induced or fed in
Implementation Method 5
the coils may be excited in a phase-offset manner by an alternating current such that the rotor is set in rotational motion
Data Source
AI summary
The invention relates to a rotating electrical flux-switching machine, comprising a rotatable tubular rotor (2), an inner first stator (3), and an outer second stator (4) that is concentric and spaced apart relative to the first stator (3), wherein the rotor (2) is arranged concentrically relative to the first and second stator (3, 4) and is arranged between the first and the second stator (3, 4) in such a way that a first air gap (10) is formed between the first stator (3) and the rotor (2), and a second air gap (11) is formed between the second stator (4) and the rotor (2). The invention also relates to an aircraft comprising a rotating electrical machine of this type.