Electric Motor Stator with Segmented Bonded Magnets
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Solution Overview
Problem
Existing electric motors experience inefficiencies due to eddy currents generated in field magnets by magnetic flux, which reduce motor efficiency and lead to stress concentration and winding collapse.
Innovation Solution
The design includes a stator with bonded magnets and field windings arranged in close contact, with the stator core featuring teeth and slots that alternate in a circumferential direction, reducing magnetic flux through the magnets and allowing for easier field winding attachment and reduced stress on the magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If field magnets are used in the stator with magnetic flux flowing through them, then the motor can generate necessary magnetic field, but eddy currents are generated in the field magnets reducing motor efficiency
Solution Approach 1:
The field magnet is divided into multiple segments along the circumferential direction, with insulating portions between adjacent magnetic poles. This segmentation interrupts the eddy current paths while maintaining the magnetic field generation capability, thereby reducing eddy current losses and improving motor efficiency.
Solution Approach 2:
Different portions of the field magnet have different properties: magnetic poles have high magnetic permeability for field generation, while interspace portions have insulating properties to block eddy currents. This local differentiation allows the field magnet to simultaneously generate magnetic field and reduce eddy current losses.
2Power
If field windings are wound around teeth with field slots, then field excitation can be achieved, but the structure becomes complex and manufacturing becomes difficult
Solution Approach 1:
The field magnet structure integrates both the magnetic pole portions and the interspace portions into a single unified component that is directly mounted on the stator core teeth. This merging eliminates the need for separate field winding assemblies and complex winding processes, simplifying manufacturing while maintaining field excitation capability through the conductive interspace portions.
Solution Approach 2:
The field magnet serves multiple functions: generating magnetic field through magnetic poles, providing field excitation through conductive interspace portions, and structurally coupling to the stator core teeth. This multi-functionality reduces the need for separate components and simplifies the overall structure.
3Ease of manufacture
If bonded magnets are used in field slots, then field magnet assembly is simplified, but stress concentration and winding collapse occur
Solution Approach 1:
The field magnet is segmented into magnetic poles and interspace portions, with the interspace portions providing flexible coupling to the stator core teeth. This segmentation distributes mechanical stress more evenly and prevents winding collapse by allowing controlled deformation in the interspace regions.
Solution Approach 2:
The field magnet uses composite construction with magnetic pole portions made of bonded magnetic material and interspace portions made of conductive material with different mechanical properties. This composite structure provides both electrical conductivity for field excitation and appropriate mechanical flexibility to prevent stress concentration and winding collapse.
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 configuration minimizes eddy currents, prevents winding collapse, and simplifies the mold formation for bonded magnets, enhancing motor efficiency and reducing stress on the magnets.
Implementation Method 1
a magnetic flux flowing through the field magnet
Implementation Method 2
the stator yoke (212) magnetically couples the teeth opposite the rotor
Implementation Method 3
an eddy current is generated in the field magnet due to a magnetic flux flowing through the field magnet
Data Source
AI summary
An electric motor includes a rotor and a stator including a stator core, a plurality of armature windings, a plurality of field windings, and a plurality of bonded magnets. The stator core has a plurality of teeth alternately defining field slots and armature slots along a circumferential direction, and a stator yoke magnetically coupling the plurality of teeth opposite the rotor. Each armature winding is wound around two of the teeth sandwiched between an adjacent pair of the armature slots. Each field winding is wound around two of the teeth sandwiched between an adjacent pair of the field slots. The magnets are individually located in the field slots while opposing the field windings in the radial direction. Each adjacent pair of the magnets along the circumferential direction respectively has an adjacent pair of pole surfaces, with the adjacent pair of pole surfaces having a same polarity.