Motor Angular Position Sensor Using Segmented Magnet Array
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Solution Overview
Problem
Existing sensor systems for determining the angular position of motor rotors, particularly in robotics and automation, face challenges with brittle ferrite rings that are prone to failure under extreme conditions like temperature and radiation, and are limited by specific geometric conditions and non-linear effects.
Innovation Solution
A sensor system utilizing a measuring body with a carrier element and a multiplicity of permanently arranged magnets, allowing for a flexible and precise arrangement of magnets with an odd number of poles, enabling a unipolar or alternating arrangement, and using magnetoresistive sensors in a bridge circuit to detect changes in the magnetic field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ferrite rings are used as magnetic reference points, then the rotor position can be measured, but the brittleness and difficulty of processing reduce reliability under extreme conditions
Solution Approach 1:
The patent replaces the traditional ferrite ring with a measuring body that copies the essential function of generating a magnetic field pattern for position measurement. This measuring body consists of multiple permanent magnets arranged on a support element, creating a comparable magnetic field distribution without the brittleness of ferrite material.
Solution Approach 2:
The invention uses a composite structure combining permanent magnets with a support element (which can be made of non-magnetic, mechanically robust materials). This composite approach maintains the magnetic field generation capability while improving mechanical strength and resistance to extreme conditions like temperature and radiation.
2Ease of manufacture
If an even number of pole pairs is used in ferrite rings, then the magnetic field pattern is standardized, but this geometric constraint limits flexibility in sensor design
Solution Approach 1:
The patent divides the magnetic field generation function into multiple independent permanent magnets instead of using a single integrated ferrite ring. This segmentation allows each magnet to be independently positioned and magnetized, enabling flexible configurations including odd numbers of poles and various magnetization patterns without geometric constraints.
Solution Approach 2:
The invention introduces flexibility in the magnetic field configuration by allowing dynamic selection of the number of permanent magnets and their magnetization directions. The support element enables easy reconfiguration of the magnetic field pattern to suit different measurement requirements, unlike the fixed geometric constraints of ferrite rings.
3Adaptability or versatility
If multiple permanent magnets are arranged in a support element, then flexibility in magnet arrangement is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple permanent magnets and the support element into a single integrated measuring body. This merging reduces the overall device complexity by eliminating the need for separate assembly of individual magnets, while still maintaining the flexibility to arrange magnets in various configurations within the unified structure.
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 solution provides a more accurate and reliable measurement of rotor position, allowing for precise position determination without the limitations of traditional ferrite rings, and can be retrofitted into existing systems for enhanced precision and flexibility.
Implementation Method 1
Sensors based on the magnetoresistive effect (MR effect) have proven effective in the past. An MR sensor changes its resistance depending on the orientation between the current direction and the magnetic field direction.
Data Source
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AI summary
Sensor system, in particular for an electric motor, comprising at least one measuring body and a sensor for detecting the change in the magnetic field caused by the movement of the measuring body. The measuring body has a support element and a plurality of permanent magnets arranged in the support element.