Synchronous Motor Rotor With Flexible Teeth For Magnet Stability
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Solution Overview
Problem
In synchronous motors with tangentially magnetized magnets, production-related tolerances can lead to instability and detachment of magnets, causing asymmetry and increased cogging forces due to inadequate gap accommodation between magnets and teeth.
Innovation Solution
The rotor design features teeth connected via flexible joints that can deflect tangentially, allowing magnets to rest against outer stops, and optionally dividing magnets into outer and inner pieces for stable positioning, with inner pieces engaging with the rotor core to maintain symmetry despite dimensional variances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If tangentially magnetized magnets are inserted between teeth of the rotor to concentrate flux, then the magnetic flux from rotor to stator is maximized, but production tolerances cause gaps between magnets and teeth leading to instability and detachment
Solution Approach 1:
The teeth are made flexible through a flexible joint connecting them to the rotor core, allowing the teeth to adapt their position dynamically. This flexibility enables the teeth to accommodate magnets within tolerance ranges while maintaining stable contact, resolving the contradiction between maximizing flux concentration and ensuring magnet stability.
Solution Approach 2:
The flexible joint changes the mechanical parameters of the tooth structure, allowing for controlled deflection and position adjustment. This parameter change enables the system to absorb dimensional variations in magnets while maintaining reliable contact and flux concentration.
2Adaptability or versatility
If gaps between teeth are designed to accommodate magnets at the upper end of tolerance range, then larger magnets can be fitted, but smaller magnets create gaps leading to loss of rotor symmetry and increased cogging forces
Solution Approach 1:
The flexible teeth can deflect to accommodate magnets of varying sizes within the tolerance range. This dynamic adjustment ensures that both smaller and larger magnets are retained stably, maintaining rotor symmetry and preventing increased cogging forces regardless of which end of the tolerance range the magnet dimensions fall into.
3Reliability
If teeth are made rigid to provide stable magnet retention, then magnets are securely held, but production tolerances cause gaps and detachment for magnets at the extremes of size variation
Solution Approach 1:
By making the teeth flexible through the flexible joint, the system transforms from a rigid structure that cannot accommodate tolerance variations to a dynamic structure that adapts to different magnet sizes. This enables reliable magnet retention while accommodating the full range of production tolerances.
Solution Approach 2:
The flexible joint introduces a change in the mechanical parameters of the tooth structure, allowing for position and shape adjustments that accommodate magnet dimensional variations while maintaining secure retention.
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 ensures stable and symmetrical magnet placement, minimizing cogging forces and maintaining precise positioning by accommodating magnets of varying sizes through adaptive deflection and engagement mechanisms.
Implementation Method 1
the teeth are connected to the rotor core via a flexible joint and that the teeth are deflected in the tangential direction
Implementation Method 2
the prevailing reluctance forces drive these magnets as far away as possible from the rotor core towards the ends of the teeth
Data Source
AI summary
A rotor for a synchronous motor includes teeth arranged at regular intervals, project from a rotor core in the radial direction, and taper in a cross-section in the direction of the rotor core. The rotor also includes tangentially magnetized magnets that are arranged in gaps between the teeth and are trapezoidal in cross-section. The teeth are connected via a flexible joint to the rotor core, and the teeth are deflected in the tangential direction such that in every other gap between two teeth, first magnets rest against outer stops at the ends of the teeth facing away from the rotor core.