Rotor Auxiliary Hole Layout for Lower Torque Ripple
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Solution Overview
Problem
In permanent magnet-assisted synchronous reluctance motors, the mismatch between the number of magnetic flux barriers and stator slots leads to difficulties in reducing torque ripples due to manufacturing limitations and limited radial dimensions of the rotor, resulting in inefficient torque generation.
Innovation Solution
The introduction of auxiliary holes with smaller sectional areas and strategically angled center lines between magnetic flux barriers, which adjust the magnetic flux distribution and reduce the influence of these holes on magnetic flux paths, thereby minimizing torque ripples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If magnets are inserted into magnetic flux barriers to form PMa-SynRM, then motor efficiency and power coefficient are improved, but torque ripple increases due to mismatch between magnetic flux barriers and stator slots
Solution Approach 1:
The magnetic flux barrier is segmented into multiple through-holes with different sizes and shapes. The rotor structure divides the magnetic flux barrier into first through-holes (circular, smaller area) and second through-holes (non-circular, larger area), allowing independent optimization of each segment's function to reduce torque ripple while maintaining efficiency
Solution Approach 2:
Different regions of the magnetic flux barrier are assigned different local properties. The first through-holes have smaller cross-sectional areas optimized for reducing torque ripple, while the second through-holes have larger cross-sectional areas optimized for magnetic flux generation. This local differentiation allows simultaneous achievement of low torque ripple and high efficiency
2Object-generated harmful factors
If the number of magnetic flux barriers is increased to match stator slots for reducing torque ripple, then torque ripple is reduced, but manufacturing difficulty increases due to magnet mounting constraints
Solution Approach 1:
The magnetic flux barrier is divided into multiple through-holes of different sizes. The first through-holes have smaller areas that are easier to manufacture and assemble, while the second through-holes have larger areas that provide sufficient space for magnet mounting. This segmentation allows achieving slot matching for torque ripple reduction without excessive manufacturing complexity
Solution Approach 2:
Instead of uniformly increasing the number and size of all through-holes, the patent applies partial action by creating only certain first through-holes with smaller areas in specific positions, while maintaining second through-holes with larger areas where magnets need to be mounted. This selective approach achieves torque ripple reduction without universally increasing manufacturing difficulty
3Object-generated harmful factors
If the radial dimension of the rotor is increased to accommodate more magnetic flux barriers, then torque ripple reduction is improved, but the overall rotor size and weight increase
Solution Approach 1:
The patent optimizes the axial dimension of the rotor by creating through-holes that extend through the axial direction of the rotor core. This allows the magnetic flux barriers to be effectively utilized along the axial dimension rather than requiring increased radial dimension, thereby reducing torque ripple without significantly increasing rotor weight
Solution Approach 2:
The through-holes are strategically positioned at specific radial distances from the rotor center (first through-holes at 30-70mm, second through-holes at 70-90mm). This localized optimization allows torque ripple reduction in critical regions without requiring uniform increases in radial dimension throughout the entire rotor, thus avoiding unnecessary weight increase
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 effectively reduces torque ripples and improves motor efficiency by optimizing the magnetic flux distribution and reducing the impact of the slotting effect, as demonstrated by performance improvements in torque ripple reduction and efficiency enhancement.
Implementation Method 1
the magnetic flux in the rotor can be adjusted, thereby effectively reducing the torque ripple of the rotor
Implementation Method 2
the magnets inserted into the magnetic flux barriers can generate additional magnetic flux and contribute a magnetic flux torque
Implementation Method 3
a reluctance torque is generated due to the reluctance difference, thereby driving the rotor to rotate
Data Source
AI summary
Embodiments of the present application provide a rotor and a motor. The rotor has a plurality of through-hole groups. Each through-hole group has a plurality of through-holes distributed in a radial direction. The rotor also has auxiliary holes. Each auxiliary hole is located between every two radially adjacent through-holes. A sectional area of each auxiliary hole is less than a sectional area of each through-hole. When a first angle, a second angle and a third angle are defined between three portions of each auxiliary hole and the q-axis respectively, the third angle is greater than or equal to the first angle, and the third angle is less than or equal to the second angle.