Arc-Shaped Magnet Hole Contour for Torque Ripple Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rotary electric machines face challenges in processing complexity and cost due to the use of hyperbola or boomerang-shaped magnetic paths, leading to difficulty in dimension management and insufficient torque generation, with conventional designs failing to maximize reluctance and magnet torque while increasing torque ripple.
Innovation Solution
The rotary electric machine features a rotor core with magnet holes formed in an arc shape along the trajectory of q-axis magnetic flux lines, allowing for simplified processing, reduced costs, and enhanced torque utilization by aligning the contour lines with magnetic flux paths, thereby maximizing reluctance and magnet torque while minimizing torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If hyperbola or boomerang-shaped magnetic paths are used to maximize reluctance torque, then torque generation is improved, but processing complexity and manufacturing cost increase
Solution Approach 1:
The patent applies curvature by forming the magnet hole contour line as an arc shape that follows the magnetic flux line trajectory, specifically using a circular arc that passes through the center line and both end sides of the magnet hole. This curved geometry maximizes the magnetic path length and reluctance torque while being manufacturable through standard arc-forming processes, avoiding the need for complex hyperbolic or boomerang-shaped contours.
2Power
If hyperbola or boomerang-shaped magnetic paths are used to maximize reluctance torque, then torque generation is improved, but dimension management becomes difficult
Solution Approach 1:
The patent employs a circular arc contour line for the magnet hole that passes through three specific points: the center line and both end sides of the magnet hole. This circular arc geometry provides simple, well-defined dimensional parameters (radius and center position) that are easy to measure and control during manufacturing, unlike complex hyperbolic or boomerang shapes that require sophisticated numerical control and dimensional management.
3Ease of manufacture
If conventional slit shapes with equal width are used, then manufacturing is simplified, but magnetic flux density distribution becomes non-uniform and torque ripple increases
Solution Approach 1:
The patent applies local quality by varying the width of the magnet hole along its contour to match the local magnetic flux density distribution. The contour line is formed as an arc that naturally adjusts the hole width at different positions, ensuring that the magnetic flux density remains uniform across the core portion. This local adaptation of geometry to functional requirements maximizes torque production while minimizing torque ripple, without requiring complex non-uniform width control.
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 design results in a cost-effective rotary electric machine with improved dimension management, increased torque production, and reduced torque ripple, achieving efficient utilization of both reluctance and magnet torque.
Implementation Method 1
a magnetic flux flowing along a d axis corresponding to a direction of a center line of each magnetic pole is defined as a d-axis magnetic flux, and a magnetic flux flowing along a q axis corresponding to a direction of a center line between the magnetic poles is defined as a q-axis magnetic flux
Implementation Method 2
the reluctance torque is torque caused by the difference between inductance Ld in the direction (d axis) of the center line of a rotor magnetic pole and inductance Lq in the direction (q axis) of the center line between magnetic poles
Implementation Method 3
both magnet torque and reluctance torque in order to generate high torque over a wide range of rotation rates
Data Source
AI summary
A contour line on the outer circumferential side of each magnet hole in the first layer is formed to be an arc passing through a total of three intersections, i.e., an intersection of a d axis and a reference magnetic flux line which is a magnetic flux line as a reference positioned inward by a predetermined number of magnetic flux lines from the outer circumferential edge of a rotor core, and intersections of: the reference magnetic flux line; and sides at the circumferential ends of the magnet hole which are positioned inward by a bridge dimension from the outer circumferential edge of the rotor core. Thus, a rotary electric machine that enables maximum utilization of reluctance torque and magnet torque and suppression of torque ripple can be obtained with simple processing and low cost.