Permanent Magnet Rotor with Offset Laminated Cores
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Solution Overview
Problem
Existing electric drive motors, particularly permanent-magnet synchronous rotor motors, face challenges in reducing cogging torque, which leads to noise and vibration issues.
Innovation Solution
The design incorporates a permanent magnet rotor with multiple pairs of poles, each with a pocket for a cuboid permanent magnet, and a stator with a specific offset angle between sheet metal packages, allowing the magnets to extend tangentially and reducing magnetic resistance variations during rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If permanent magnets are arranged in pockets of a laminated core, then the motor structure is simplified and manufacturing is easier, but cogging torque increases causing noise and vibration
Solution Approach 1:
The rotor is divided into multiple laminated cores (first laminated core, second laminated core, etc.) arranged axially on the motor shaft. Each laminated core contains pockets with permanent magnets. This segmentation allows the magnetic fields from different laminated cores to be offset from each other, reducing the overall cogging torque while maintaining the simple pocket structure for easy manufacturing.
Solution Approach 2:
The rotor uses a composite structure combining multiple laminated cores with different angular positions. The laminated cores are made of stacked sheet metal layers providing magnetic pathways, while pockets contain permanent magnets. This composite approach enables the superposition of magnetic fields from multiple laminated cores to reduce cogging torque effects.
2Device complexity
If the laminated core has a circular circumferential contour, then the motor structure is simple, but magnetic resistance varies during rotation causing vibrations
Solution Approach 1:
The laminated cores are designed with asymmetric circumferential contours that deviate from perfect circles. Each laminated core has specific arc-shaped sectors with different curvatures in different regions. This asymmetric design causes the magnetic resistance variations from multiple laminated cores to be out of phase, reducing overall vibrations while maintaining relatively simple structural forms.
3Object-generated harmful factors
If multiple laminated cores are added to reduce cogging torque, then noise and vibrations decrease, but the device complexity increases
Solution Approach 1:
The rotor is segmented into multiple laminated cores (at least a first and second laminated core) arranged axially on the motor shaft. Each laminated core is identical in structure but offset by a specific angle relative to the others. This segmentation reduces cogging torque and noise through magnetic field offset while using repeated modular units to limit complexity.
Solution Approach 2:
The laminated cores are pre-designed with specific asymmetric circumferential contours and arc-shaped sectors configured to produce magnetic field offsets. By pre-configuring the angular offsets and geometric shapes during manufacturing, the system achieves vibration reduction without requiring complex real-time control or additional components during operation.
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 significantly reduces locking torques and noise, resulting in a quieter operation by minimizing vibrations and magnetic field interactions.
Implementation Method 1
an electric drive motor (1) comprising a stator (2) with pole shoes (4) and at least one electrically controllable stator winding, and a permanent magnet rotor (3) rotatably mounted in the field of the stator winding
Implementation Method 2
allowing the magnets to extend tangentially and reducing magnetic resistance variations during rotation
Data Source
Figure 1
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AI summary
The invention relates to an electric drive motor (1) comprising a stator (2) with pole shoes (4) and at least one electrically controllable stator winding, and a permanent magnet rotor (3) rotatably mounted in the field of the stator winding while leaving an annular gap (6), the rotor comprising a motor shaft (7) and a first laminated core (8.1) mounted on the motor shaft (7), the first laminated core having a number of pockets (10) corresponding to the number of poles (14.1) of the permanent magnet rotor, each pocket containing a permanent magnet (11), and the first laminated core (8.1) having a circumferential contour in its axial cross-section that deviates from a circular shape, which in each sector of the first laminated core (8.1) assigned to a permanent magnet (11) has an arc shape with a greater curvature than a circular circumferential contour enclosing the first laminated core (8.1) in cross-section, and comprising at least one of the first laminated cores (8.1) A correspondingly designed second laminated core (8.2) which is arranged on the motor shaft (7) of the permanent magnet rotor (3) offset from the first laminated core (8.1) by an offset angle rotated about the axis of rotation (D) of the permanent magnet rotor (3). The invention also relates to a household appliance with such an electric drive motor (1).