Stator Teeth Geometry for Halbach Array Flux Leakage
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Solution Overview
Problem
In rotary electric machines with a Halbach array, significant magnetic flux leakage occurs due to insufficient magnetic flux reception by the stator, leading to heat generation and reduced electrical power output.
Innovation Solution
The design includes a stator with annular yoke and teeth portions having specific geometric configurations, such as a flange portion wider than the base portion and an expanding portion with a controlled angle of intersection, to effectively receive and reduce magnetic flux leakage, enhancing torque and reducing heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a Halbach array is adopted to arrange permanent magnets, then magnetic flux density increases and efficiency is improved, but magnetic flux leakage occurs and heat is generated
Solution Approach 1:
The teeth portions are designed with non-uniform cross-sectional areas along their length, with the cross-sectional area increasing from the tip toward the base. This local variation in geometry creates regions of different magnetic permeability and flux capacity, allowing the teeth to efficiently capture and guide magnetic flux while reducing leakage at critical locations.
Solution Approach 2:
The invention introduces a dimensional variation in the teeth portions by changing their cross-sectional area along the radial direction. This dimensional change adds a new degree of freedom for controlling magnetic flux distribution, enabling the teeth to both receive flux effectively and minimize leakage simultaneously.
2Force
If permanent magnets are arranged in a Halbach array, then torque is enhanced, but leakage flux increases causing heat generation
Solution Approach 1:
The teeth portions are designed with non-uniform cross-sectional areas along their length, with the cross-sectional area increasing from the tip toward the base. This local variation in geometry creates regions of different magnetic permeability and flux capacity, allowing the teeth to efficiently capture and guide magnetic flux while reducing leakage at critical locations.
Solution Approach 2:
The invention converts the potentially harmful leakage flux into beneficial effect by designing the teeth geometry to guide the flux through a controlled path. The varying cross-sectional area directs the magnetic flux to follow the teeth structure, transforming what would be wasted leakage flux into useful magnetic coupling that enhances torque while reducing heat generation.
3Ease of manufacture
If the stator uses conventional teeth design, then manufacturing is simple, but magnetic flux reception is insufficient
Solution Approach 1:
The teeth portions are designed with non-uniform cross-sectional areas along their length, with the cross-sectional area increasing from the tip toward the base. This local variation in geometry creates regions of different magnetic permeability and flux capacity, allowing the teeth to efficiently capture and guide magnetic flux while reducing leakage at critical locations.
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 configuration increases magnetic flux reception, enhances torque, and minimizes heat generation by reducing interlinked magnetic flux and eddy currents, thereby improving the efficiency and power output of the rotary electric machine.
Implementation Method 1
a first magnet in which a magnetic field thereof is oriented in a radially outward direction of the yoke portion, a second magnet adjacent to the first magnet and in which a magnetic field thereof is oriented in a clockwise direction of the yoke portion, a third magnet adjacent to the first magnet and in which a magnetic field thereof is oriented in a counterclockwise direction of the yoke portion, and a fourth magnet adjacent to the third magnet and in which a magnetic field thereof is oriented in a radially inward direction of the yoke portion
Implementation Method 2
An electromagnetic coil is provided in slots that are formed in the stator, in a manner so as to straddle over respective teeth portions. On the other hand, permanent magnets are retained on the rotor. In a motor, accompanying energization or supply of current to the electromagnetic coil, the electromagnetic coil is brought into a magnetic state, and an alternating magnetic field is formed. Repulsive forces or attractive forces are generated by the alternating magnetic field and the magnetic fields generated by the permanent magnets, whereby the rotor is rotated.
Implementation Method 3
the flange portion disposed in closer proximity to the rotor than the base portion, and configured to be wider than the base portion, and an expanding portion interposed between the base portion and the flange portion, and configured to become wider in an expanding manner from the base portion toward the flange portion
Data Source
AI summary
A rotor of a rotary electric machine includes a first magnet and a fourth magnet whose magnetic fields are oriented in radial directions of a stator, and a second magnet and a third magnet whose magnetic fields are oriented in circumferential directions of the stator. Teeth portions of the stator each include a base portion that protrudes in a radially inward direction of a yoke portion, a flange portion that is wider than the base portion, and an expanding portion interposed between the base portion and the flange portion. An angle of intersection between the base portion and the expanding portion is 108° to 130°. A distance (thickness) from an inner circumferential side end part to an outer circumferential side end part of the flange portion is 0.2 mm to 2.0 mm.