Rotor Position Sensor Device Using Linear Matrix Signal Processing
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Solution Overview
Problem
Existing sensor devices for determining the position of a rotor in electrical machines face challenges in achieving high accuracy due to interference fields and field distortions, especially when operated close to magnetic saturation, which affects the precision of position measurement.
Innovation Solution
A sensor device utilizing multiple magnetic sensors to acquire and digitize sensor signals, forming measurement vectors that are processed using specific linear functions and matrices to eliminate unwanted signal components, allowing for precise determination of rotor and stator positions despite interference and field distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic sensors are arranged in the area of the magnetic field generated by the stator to detect rotor position, then position detection is enabled, but the stator represents a strong source of interference fields that reduces measurement accuracy
Solution Approach 1:
The patent extracts and eliminates the harmful stator interference field components from the sensor signals through signal processing. By using multiple sensors and applying linear functions with specifically designed matrices, the system separates the useful rotor position information from the harmful stator interference, effectively removing the interference before position calculation.
Solution Approach 2:
The patent converts the harmful stator interference fields into useful information by designing the signal processing to identify and eliminate specific interference patterns. The interference fields, while harmful in themselves, provide characteristic signal patterns that can be recognized and removed through the matrix operations, turning a disadvantage into a solvable problem.
2Power
If electric motors are operated close to or in the saturation of the magnetic material to increase performance, then power output is improved, but field distortions generate sensor signals with harmonics that reduce accuracy or make position determination impossible
Solution Approach 1:
The patent converts the harmful harmonic distortions caused by magnetic saturation into manageable signal components. By using multiple sensors and applying specifically designed linear functions with matrices that account for harmonic content, the system can distinguish between fundamental position-related signals and harmonic distortions, effectively using the saturation conditions to generate distinguishable signal patterns.
Solution Approach 2:
The patent segments the sensor signals into different frequency components and spatial patterns using multiple sensors and linear transformation matrices. This segmentation allows the system to separate the fundamental rotor position information from harmonic distortions caused by magnetic saturation, processing each component appropriately to maintain accuracy at high power levels.
3Measurement precision
If inductive or optical sensor systems are used for position detection to ensure precise measurement, then measurement accuracy is improved, but the sensor systems take up a lot of space and are expensive
Solution Approach 1:
The patent uses inexpensive magnetic sensors instead of expensive inductive or optical sensor systems. While magnetic sensors individually have lower precision, the system compensates through clever signal processing using multiple sensors and mathematical transformations, achieving high accuracy with low-cost components that are simpler and more compact than alternative technologies.
Solution Approach 2:
The patent makes the magnetic sensor system multi-functional by using the same sensors for both position detection and for characterizing the magnetic field environment. The sensors simultaneously perform position measurement and provide data for interference field analysis, reducing the need for additional specialized components and simplifying the overall system.
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 enables accurate determination of rotor and stator positions with high integration density, achieving robust and precise motor control, even under conditions of magnetic saturation and interference, thereby enhancing the performance of electric motors.
Implementation Method 1
The magnetic system includes a permanent magnet mounted on the rotor axis, which acts as a rotary encoder, and at least two sensors that detect the magnetic field generated by the rotary encoder.
Implementation Method 2
In many motor types, the stator coils are operated with three-phase current, which also reduces their magnetic field rotates around the motor axis.
Implementation Method 3
In order to increase performance, electric motors are often operated close to or in the saturation of the magnetic material of the stator and/or rotor.
Data Source
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AI summary
The invention relates to a sensor device (10) for determining the position φ1 of the rotor (1) of an electric machine, for example, an electric motor (8) or an electric generator. The sensor device (10) comprises a number r of sensors (S1, S2, S3) that detect the magnetic field generated by the rotor (1) and/or a rotating permanent magnet (4), and an electronic circuit configured to acquire and digitize the sensor signals a1 to ar and to form a signal vector a = (a1,..., ar), to form a measurement vector q according to a predetermined linear function g such that q→=ga→, to calculate a vector p→=Mrot1⋅q⇀, where p is a 2-vector with components p1 and p2 and Mrot1 is a 2 x n matrix, and to determine the position φ1 such that φ1 =atan2(p2, p1). The invention further relates to a control device (9) for an electric motor (8) with such a sensor device (10).