Power Tool SynRM Rotor Magnet Layout for Lower Harmonic Distortion
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Solution Overview
Problem
Existing power tools with permanent magnet-assisted synchronous reluctance motors face inefficiencies and harmonic distortions due to suboptimal design of stator and rotor configurations, particularly in the arrangement and composition of magnets and stator windings.
Innovation Solution
The power tool incorporates a stator with multiple stator teeth and a rotor featuring specific magnet housing portions and magnet arrangements, utilizing ferrite and rare earth magnets, along with steel ribs to optimize magnetic flux distribution and reduce harmonic distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional permanent magnet motor designs are used, then the motor can operate, but it produces significant harmonic distortions and efficiency losses due to suboptimal magnetic flux distribution
Solution Approach 1:
The rotor is segmented into multiple poles (at least four) with slots positioned at specific angular intervals, allowing independent optimization of magnetic flux distribution in different regions. This segmentation enables reduction of harmonic distortions by controlling the spatial arrangement of magnets and steel ribs across multiple discrete poles rather than using a single continuous structure
Solution Approach 2:
Steel ribs are strategically positioned within specific rotor slots at localized regions where harmonic distortions occur. The ribs have varying cross-sectional areas and positions depending on the local magnetic flux requirements. This local quality approach allows targeted correction of harmonic distortions in specific areas without uniformly increasing the complexity of the entire motor structure
Solution Approach 3:
The rotor employs a composite structure combining permanent magnets with steel ribs within the same rotor assembly. The steel ribs (with different magnetic permeability) are integrated alongside the permanent magnets in the rotor slots, creating a composite magnetic circuit that optimizes flux distribution and reduces harmonic distortions while maintaining overall structural efficiency
2Power
If more permanent magnets are added to increase motor performance, then power output improves, but manufacturing complexity and cost increase
Solution Approach 1:
The motor design uses at least four rotor poles with discrete slots and magnets arranged at specific angular intervals rather than a continuous magnet structure. This segmentation allows for standardized mass production of individual pole assemblies that can be replicated and assembled, simplifying manufacturing while achieving high power output through the cumulative effect of multiple poles
Solution Approach 2:
The invention optimizes power output by precisely controlling parameters such as the angular position of rotor slots, the cross-sectional area of steel ribs, and the spacing between magnets rather than simply increasing the total amount of magnetic material. These parameter optimizations achieve high power efficiency with moderate magnet quantities, reducing manufacturing complexity compared to designs that rely on excessive magnet usage
3Ease of manufacture
If the rotor and stator configurations are simplified to reduce manufacturing complexity, then production becomes easier, but magnetic flux distribution becomes suboptimal causing efficiency losses
Solution Approach 1:
Rather than uniformly complicating the entire motor structure, steel ribs are added only in specific rotor slots where local magnetic flux optimization is needed. The ribs have varying dimensions and positions tailored to local requirements, achieving overall flux distribution optimization without uniformly increasing manufacturing complexity across the entire motor
Solution Approach 2:
The invention applies the principle of partial action by adding steel ribs only in certain rotor slots rather than in all slots, and only where needed to correct specific harmonic distortion issues. This partial optimization approach achieves sufficient energy efficiency improvement without the excessive manufacturing complexity that would result from uniformly modifying every rotor slot
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 enhances the efficiency and performance of the permanent magnet-assisted synchronous reluctance motor by improving magnetic flux distribution and reducing harmonic distortions, leading to improved power tool operation.
Implementation Method 1
a permanent magnet assisted synchronous rotor motor including a stator including a plurality of stator teeth configured to receive a plurality of stator coils and a rotor
Implementation Method 2
The first magnet is composed of a ferrite metal material and the second magnet is composed of a rare earth metal material
Data Source
AI summary
A power tool includes a permanent magnet assisted synchronous rotor motor. The motor includes a stator and a rotor. The rotor includes a first slot located between an external circumferential surface of the rotor. The first slot includes a first magnet housing portion. The first magnet housing portion located a first radial distance away from a center of rotation of the rotor. The rotor includes a second slot located between the external circumferential surface of the rotor and the first slot. The second slot includes a second magnet housing portion. A second length of the second slot is shorter than a first length of the first slot, and the second magnet housing is located a second radial distance away from the center of rotation of the rotor.