Magnetic Rotor Position Sensor With Ferromagnetic Bearing Reference
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Solution Overview
Problem
Rotating electrical machines, particularly synchronous reluctance machines, face challenges in accurately measuring the angular position of the rotor due to mechanical and magnetic disturbances, which affect the precision and reliability of position sensors, especially at high speeds.
Innovation Solution
A magnetic position sensor is integrated into the machine with a ferromagnetic bearing that serves as a new mechanical reference, separating the rotating and fixed parts of the sensor and providing a non-magnetic insert to protect the magnet from magnetic field lines, ensuring precise and robust position measurement independent of mechanical disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic position sensor is used to measure rotor angular position, then measurement precision is improved, but the sensor becomes sensitive to mechanical and magnetic disturbances that reduce reliability
Solution Approach 1:
A ferromagnetic bearing is introduced as an intermediary element between the rotating shaft and the position sensor. This bearing serves as a magnetic shield that guides magnetic field lines, preventing them from directly reaching the position sensor magnet. The bearing acts as a mediator that blocks harmful magnetic disturbances while allowing the sensor to continue measuring rotor position accurately.
Solution Approach 2:
The position sensor is extracted from direct contact with the rotating shaft by introducing a ferromagnetic bearing as a separator. The bearing is mounted on the shaft while the position sensor is mounted separately on the stator, creating physical and magnetic separation. This extraction removes the sensor from the harmful magnetic environment while maintaining measurement capability.
2Stability of the object's composition
If intermediate components are added between the position sensor and the shaft bearing, then mechanical reference stability is improved, but device complexity increases
Solution Approach 1:
The ferromagnetic bearing serves multiple functions simultaneously: it provides mechanical support for the rotating shaft, acts as a magnetic shield to protect the position sensor, and establishes a stable mechanical reference for the sensor assembly. By combining these functions in a single component, the solution improves stability without proportionally increasing complexity.
Solution Approach 2:
The ferromagnetic bearing merges the mechanical support function with the magnetic shielding function into a single integrated component. Rather than adding a separate shield to the existing bearing, the bearing itself is made of ferromagnetic material, combining structure and protection in one element.
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 solution ensures precise and robust measurement of the rotor's angular position, maintaining high sealing integrity and cost-effectiveness, while minimizing the impact of mechanical and magnetic disturbances, thus enhancing the reliability and accuracy of the position sensor.
Implementation Method 1
the bearing supporting the rotating shaft, which is made of a ferromagnetic material, preferably a ferromagnetic steel
Implementation Method 2
a fixed part 12 containing several Hall effect magnetic sensors. The Hall effect magnetic sensors of the fixed part 12 detect the amplitude of the rotating magnetic field created by the magnet rotating with the shaft
Data Source
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AI summary
The invention relates to a rotating electrical machine (100) including a magnetic sensor (101) for obtaining the angular position of the rotor (150). The sensor comprises a rotating part (108) with a magnet (102), which is secured to the end (160b) of the rotating shaft (160) at the rear of the machine and faces a stationary part (103) comprising Hall effect sensors and mounted on a stationary support (106) connected to the casing of the machine. The machine comprises a bearing (104) centred on the axis (X), separating the rotating and stationary parts of the sensor. The bearing, which is secured to the shaft and to the metal support of the stationary part of the sensor, and preferably in contact with the rotating part, forms a new mechanical reference close to the sensor. The invention supplies precise and robust position information, irrespective of mechanical and magnetic disturbances that may occur on the shaft.