Bezier-Shaped Permanent Magnet for Torque Pulsation Reduction
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Solution Overview
Problem
Existing electrical machines with permanent magnets suffer from torque pulsations, such as cogging and ripple torque, which cause vibrations and acoustic noise, and are costly due to the need for numerous magnets, and existing optimization techniques like magnet shaping and chamfering do not adequately reduce these issues.
Innovation Solution
A permanent magnet with a surface defined by a Bezier function connecting three points, optimizing magnetic flux density distribution and reducing magnet volume, cogging torque, and ripple torque through iterative parameter adjustment, applicable to various magnetic geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional magnet shaping or chamfering is used, then manufacturing is simpler, but cogging torque and ripple torque are not reduced to a satisfactory level
Solution Approach 1:
The patent applies curvature to the magnet surface by using a Bezier function to define the transition area between the flat top surface and the base plane. This curved geometry, specifically the Bezier-shaped transition area, effectively reduces cogging torque and ripple torque while maintaining manufacturing feasibility, resolving the contradiction between manufacturing simplicity and torque reduction performance.
2Quantity of substance
If the number of permanent magnets is minimized to reduce costs, then manufacturing cost decreases, but torque pulsations and vibrations increase
Solution Approach 1:
The patent changes the geometric parameters of the magnet by introducing a Bezier function with specific control points to define the surface shape. This parameter change in the magnet geometry optimizes the magnetic flux density distribution, allowing for reduced number of magnets while maintaining acceptable torque pulsation levels, thus resolving the contradiction between quantity reduction and performance maintenance.
3Quantity of substance
If magnet volume is reduced to lower cost, then material cost decreases, but magnetic flux density and efficiency may be compromised
Solution Approach 1:
The patent applies local quality by creating a non-uniform magnet geometry where the Bezier-shaped transition area concentrates magnetic flux in specific regions. This local optimization of magnetic flux density distribution ensures that even with reduced overall magnet volume, the critical areas maintain sufficient flux density to preserve electrical machine output power and 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
The Bezier-shaped magnet surface achieves a balance between reduced magnet volume, improved efficiency, and minimized torque pulsations, resulting in enhanced electrical machine performance and output power with fewer design constraints.
Implementation Method 1
The permanent magnet contains a surface, which is aligned to the coil and to the air gap in a way, that magnetic forces of the permanent magnet interact via the surface and the air gap with the coil by a magnetic flux density distribution.
Implementation Method 2
The permanent magnet and the coil are arranged in a way that electrical power is generated in the coil when the permanent magnet or the coil is moved in their relative position to each other.
Data Source
AI summary
An electrical machine including a permanent magnet and a coil is provided. The coil is arranged to interact with the permanent magnet via an air gap, which located between the two. Electrical power is generated in the coil when the permanent magnet or the coil is moved in their relative position to each other. The permanent magnet includes a surface, which is aligned to the coil and to the air gap so that that magnetic forces of the permanent magnet interact via the surface and the air gap with the coil by a magnetic flux density distribution. The permanent magnet also includes a base plane and a transition area. A first side of the surface is connected with the adjacent base plane via the transition area. The cross-section of the transition between the surface and the adjacent base plane is determined by a Bezier function.