Permanent Magnet Motor Geometry to Suppress Demagnetization
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Solution Overview
Problem
The challenge lies in balancing the thickness of permanent magnets in motors to minimize demagnetization while controlling manufacturing costs, as thicker magnets reduce demagnetization but increase material usage and costs, while thinner magnets increase processing costs and demagnetization risk.
Innovation Solution
The motor design incorporates permanent magnets with a thickness of at least 2.1 mm, optimized stator and rotor configurations, and specific coil winding to minimize magnetic flux exposure, ensuring sufficient magnetization and reducing demagnetization while maintaining cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the permanent magnet is increased, then demagnetization resistance is improved, but manufacturing cost increases due to increased material usage
Solution Approach 1:
The patent applies parameter changes by optimizing the permanent magnet thickness to a specific range (2.0mm to 4.0mm) and adjusting the air gap length to achieve the optimal balance between demagnetization resistance and manufacturing cost. This quantitative parameter optimization resolves the contradiction by finding the precise threshold where reliability improves without proportionally increasing material costs.
Solution Approach 2:
The patent implements local quality by positioning the permanent magnet thickness optimization specifically in the radial direction where demagnetization risk is highest, while maintaining other dimensions according to standard design requirements. This targeted approach improves demagnetization resistance only where needed, avoiding unnecessary increases in overall material usage and manufacturing cost.
2Ease of manufacture
If the thickness of the permanent magnet is decreased, then manufacturing cost is reduced, but demagnetization risk increases
Solution Approach 1:
The patent establishes a minimum thickness parameter of 2.0mm for the permanent magnet, below which demagnetization risk becomes unacceptable. This parameter threshold ensures that cost reduction through thinning does not compromise reliability, as the optimized thickness range maintains sufficient magnetic flux density to prevent demagnetization under normal operating conditions.
Solution Approach 2:
The patent converts the potentially harmful effect of reduced magnet thickness into a benefit by simultaneously optimizing the air gap length. This combination allows for thinner magnets (cost reduction) while the adjusted air gap compensates for the reduced magnetic strength, maintaining demagnetization resistance and effectively turning the harmful thinning effect into a cost-saving advantage.
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 approach effectively suppresses demagnetization and reduces manufacturing costs by optimizing magnet thickness and motor geometry, ensuring efficient operation and extended lifespan.
Implementation Method 1
a motor in which a permanent magnet is attached to a rotor and a coil is attached to a stator
Implementation Method 2
demagnetization of the permanent magnet may be caused by a magnetic flux generated in the coil of the stator
Implementation Method 3
demagnetization of the permanent magnet may be caused by a magnetic flux generated in the coil of the stator
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A motor includes a rotor and a stator provided so as to surround the rotor. The rotor has a rotor core having a magnet insertion hole and a permanent magnet disposed in the magnet insertion hole and is rotatable about a rotation axis. The stator has a stator core with a tooth facing the rotor, and a coil wound around the tooth. The permanent magnet has a thickness thicker than or equal to 2.1 mm in a direction in which the permanent magnet faces the stator and is magnetized in a direction of the thickness. A minimum gap AG (mm) between the rotor and the stator, a winding number Nt of the coil around the tooth, an overcurrent threshold Ip (A) for a current flowing through the coil, and a lower limit Hct (kA/m) of a coercive force of the permanent magnet satisfy Hct ≥ 0.4 × (Ip × Nt/AG) + 410.