Multipolar Magnetic Ring Geometry for Sinusoidal Signal Purity
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Solution Overview
Problem
Existing angular position determination devices for polyphase rotating electric machines face challenges in producing pure sinusoidal signals due to high harmonic levels, which are sensitive to assembly dispersions, mechanical tolerances, material characteristics, and operating temperature, and lack precise information on signal purity.
Innovation Solution
A magnetic device comprising a multipolar magnetic ring with optimized radial thickness and air gap dimensions, along with a magnetic sensor, produces a sinusoidal signal with reduced harmonic levels by controlling the radial thickness between 1 mm and 5 mm, air gap between 1 mm and 4 mm, and a first ratio of thickness to air gap between 0.4 and 2.3, and a second ratio of height to thickness between 1.5 and 8, minimizing sensitivity to mechanical and thermal dispersions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall effect or magnetoresistance sensors are used for angular position determination, then the device can determine angular position, but the signals contain high levels of harmonics requiring additional processing
Solution Approach 1:
The patent changes the geometric parameters of the magnetic target (multipolar magnetic ring) including its radial thickness e, axial height h, and the air gap E between the sensor and target. By optimizing these parameters (e/E ratio between 0.4 and 2.3, h/e ratio between 1.5 and 8), the magnetic field distribution is modified to produce sinusoidal signals with reduced harmonic content directly at the sensor output, eliminating the need for additional signal processing
2Object-generated harmful factors
If a multipolar magnetic ring is used to create a magnetic field for sinusoidal signal generation, then harmonic levels are reduced, but the signal purity is sensitive to assembly dispersions and mechanical tolerances
Solution Approach 1:
The patent optimizes the geometric parameters (radial thickness e between 1mm and 5mm, air gap E between 1mm and 4mm, axial height h) to create a magnetic field distribution that is inherently less sensitive to assembly dispersions and mechanical tolerances. This parameter optimization ensures that the sinusoidal signal purity is maintained across varying operating conditions and temperature ranges
Solution Approach 2:
The optimized geometric design of the multipolar magnetic ring pre-compensates for potential assembly dispersions and mechanical tolerances by creating a magnetic field distribution that is robust to variations. The specific e/E and h/e ratios are designed to cushion against the effects of manufacturing variations and operating condition changes, ensuring stable signal quality
3Object-generated harmful factors
If the radial thickness of the magnetic ring is increased to reduce harmonic distortion, then signal purity improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent establishes specific parameter ranges (radial thickness e: 1-5mm, air gap E: 1-4mm, axial height h: 1.5-8 times e) that balance signal purity with manufacturing feasibility. These optimized parameters reduce harmonic distortion while keeping the device dimensions within practical manufacturing capabilities, avoiding excessive complexity
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 magnetic device effectively reduces harmonic distortion, maintaining signal amplitude and purity across varying conditions, ensuring robust control of rotating electrical machines without additional signal processing.
Implementation Method 1
a multipolar magnetic ring movable in rotation around an axis and creating a variable magnetic field as a function of an angle of rotation
Implementation Method 2
a magnetic sensor placed in this magnetic field and generating this sinusoidal signal
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3
AI summary
The invention relates to a device that includes: a multipolar magnetic ring (2) capable of rotating about an axis (R’R) and generating a variable magnetic field based on a rotation angle; a magnetic sensor (3) located in the magnetic field and generating a sinusoidal signal; an air gap defined by a distance E between the sensor and the ring in a radial plane (XOY). According to the invention, a first ratio e/E between a thickness e of the ring (2) in a radial direction (OX) and the air gap E is 0.4 to 2.3. Preferably, a second ratio h/e between the height h of the ring (2) in an axial direction (OY) and the thickness e is 1.5 to 8. According to other preferred characteristics, the thickness e is 1 mm to 5 mm, and the air gap E is 1 mm to 4 mm.