Laminated Compaction Plate for Low-Loss Electric Machine Rotors
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Solution Overview
Problem
High-power electric machines face inefficiencies due to clamping plates made of steel, which increase mass and generate parasitic harmonics, leading to core losses and warming, while existing solutions like electromagnetic shields also increase mass and are not suitable for high-power applications.
Innovation Solution
A compaction plate system using laminated magnetic sheets fixed with electric insulating means, such as glue and bosses, to maintain the magnetic mass compacted without the need for massive clamping plates, reducing mass and parasitic harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If massive steel clamping plates are used to compact the magnetic mass, then the magnetic sheets are held firmly compacted, but the mass of the rotor increases and parasitic harmonics are generated causing core losses and warming
Solution Approach 1:
The single massive clamping plate is segmented into multiple thin magnetic sheets (e.g., 10-20 sheets of 0.5mm each). These segmented sheets collectively provide the necessary compaction force while significantly reducing the total mass compared to a single solid plate. The segmentation also interrupts parasitic current paths, reducing eddy current losses.
Solution Approach 2:
The clamping structure transitions from homogeneous steel to a composite structure of multiple thin magnetic sheets separated by insulating layers (varnish, oxide, or adhesive). This composite structure maintains mechanical strength for compaction while the insulating layers block parasitic current paths, reducing core losses and heating.
2Loss of energy
If electromagnetic shields made of massive copper or aluminum disks are implemented to minimize parasitic harmonics, then core losses and warming are reduced, but the mass of the rotor or stator increases
Solution Approach 1:
The electromagnetic shields (copper or aluminum disks) are completely removed from the rotor structure. Instead, the patent uses thin magnetic sheets with insulating layers that inherently suppress parasitic harmonics through their laminated structure, eliminating the need for additional shielding components and their associated mass.
Solution Approach 2:
The insulating layers between magnetic sheets, which are necessary to prevent eddy currents, are converted into a beneficial structure that simultaneously suppresses parasitic harmonics. The layered structure with insulating interfaces acts as a natural barrier to high-frequency magnetic flux, turning a potential weakness into a harmonic suppression mechanism.
3Temperature
If resin molded plates are used to fix magnets in holes, then the plates do not warm up under magnetic field, but they are not rigid enough to maintain the magnetic mass compacted
Solution Approach 1:
The functions of magnetic material and structural clamping element are merged into a single component. The thin magnetic sheets serve both as the magnetic circuit material and as the clamping structure, eliminating the need for separate resin molded plates. The sheets are held firmly by the overall assembly structure while contributing to the magnetic flux path.
4Weight of moving object
If gluing laminated magnetic sheets is used to suppress the compaction plate, then the mass is reduced, but the process is time consuming and suitable only for small length magnetic mass
Solution Approach 1:
The mechanical gluing process is replaced by a structure-based retention system. The thin magnetic sheets are held firmly compacted by the overall assembly structure, including the interaction between sheets and the external clamping mechanism, eliminating the need for time-consuming adhesive application while maintaining structural integrity.
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 decreases the mass and volume of the electric machine, improves torque generation, and reduces warming, enhancing efficiency by eliminating the need for electromagnetic shields and maintaining the magnetic mass compacted effectively.
Implementation Method 1
fixing and electric insulating means comprise glue disposed between two adjacent laminated magnetic sheets
Implementation Method 2
Under the effect of magnetic fields, currents are generated inside the clamping plates warming up the electric machine
Implementation Method 3
a first compaction element comprising a compaction plate, the laminated magnetic sheets being fixed together
Data Source
AI summary
A compaction plate for magnetic mass is proposed.The compaction plate comprises a plurality of laminated magnetic sheets, the laminated magnetic sheets being fixed together with fixing and electric insulating means.