Lundell Rotor with Sensor Magnet for Position Detection
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Solution Overview
Problem
Brushless motors with Lundell-type rotors face challenges in accurately detecting the rotation position due to magnetic flux leakage and interference from stator teeth, leading to reduced detection accuracy and efficiency.
Innovation Solution
The rotor design includes a Lundell-type structure with alternating claw-shaped magnetic poles and a sensor magnet positioned to minimize magnetic flux leakage, using back surface auxiliary magnets and interpolar magnets to reduce interference, and a sensor magnet with alternating magnetic poles to enhance detection signal switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor magnet is arranged on the rotor core to detect rotation position, then rotation position detection is enabled, but magnetic flux leakage and interference from stator teeth reduce detection accuracy
Solution Approach 1:
A detected portion (sensor magnet) is introduced as an intermediary element between the rotor core and the detection system. This sensor magnet generates a dedicated magnetic flux for detection purposes, separate from the main driving magnetic flux, thereby enabling accurate rotation position detection while isolating the detection function from the harmful magnetic flux leakage and stator tooth interference that affect the main magnetic circuit
Solution Approach 2:
The magnetic circuit is segmented into distinct functional zones: the main magnetic circuit for motor operation (field magnet → rotor core → stator) and the detection magnetic circuit (sensor magnet → detected portion). This segmentation allows the detection function to operate independently with its own magnetic flux path, preventing interference from the main circuit's magnetic flux leakage and stator tooth effects
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 improves the accuracy of rotation position detection and reduces magnetic flux leakage, resulting in enhanced motor efficiency and stability.
Implementation Method 1
The field magnet is arranged between the first and second core bases in the axial direction. The field magnet is magnetized in the axial direction so that the first claw-shaped magnetic pole portions function as first magnetic poles and the second claw-shaped magnetic pole portions function as second magnetic poles.
Implementation Method 2
The detected portion generates magnetic flux for detecting rotation positions of the first rotor core and the second rotor core.
Data Source
AI summary
A rotor includes a first rotor core, a second rotor core, a field magnet, and a detected portion. The first rotor core includes a first core base and a plurality of first claw-shaped magnetic pole portions. The second rotor core includes a second core base and a plurality of second claw-shaped magnetic pole portions. The first and second core bases face to each other, and the first and second claw-shaped magnetic pole portions are alternately arranged in the circumferential direction. The field magnet is located between the first and second core bases in the axial direction. The field magnet has the first claw-shaped magnetic pole portion function as a first magnetic pole and has the second claw-shaped magnetic pole portion function as a second magnetic pole. A detected portion, which generates a magnetic flux, is arranged at an outer axial end surface of the first rotor core.