Rotor Position Sensor with Magnetic and Inductive Redundancy
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Solution Overview
Problem
Existing rotor position sensors in electric motor vehicles are susceptible to interference from stray magnetic fields, particularly in electrified vehicles, and face reduced measurement range when redundancy is required, compromising operational reliability.
Innovation Solution
A rotor position sensor combining magnetic and inductive measuring principles on a single encoder element, with diverse redundancy, using a magnetic field sensor and an inductive coil system operating in different frequency ranges, and featuring electrically conductive areas for shielding and improved redundancy, allowing for error detection and interference minimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic field sensor is used to detect rotor position, then the sensor can determine angular position, but the sensor becomes susceptible to interference from stray magnetic fields
Solution Approach 1:
The patent combines a magnetic field sensor and an inductive sensor into a single integrated rotor position sensor. The magnetic field sensor detects the magnetic field from the rotor magnet, while the inductive sensor detects changes in inductance caused by the rotor magnet's position. This merging of two different sensing principles allows the system to cross-validate measurements and reject interfering signals, thereby maintaining measurement precision while reducing susceptibility to stray magnetic fields.
Solution Approach 2:
The patent introduces an evaluation unit that acts as an intermediary between the sensor elements and the control unit. This evaluation unit processes signals from both the magnetic field sensor and inductive sensor, compares them, and determines whether interference is present. By using this intermediary processing layer, the system can filter out stray magnetic field interference while preserving accurate angular position data.
2Reliability
If redundant measurement systems are implemented, then operational reliability improves, but the measuring range is reduced
Solution Approach 1:
The patent merges a magnetic field sensor and an inductive sensor into a single integrated rotor position sensor. The magnetic field sensor detects the magnetic field from the rotor magnet, while the inductive sensor detects changes in inductance caused by the rotor magnet's position. This merging of two different sensing principles allows the system to cross-validate measurements and reject interfering signals, thereby maintaining measurement precision while reducing susceptibility to stray magnetic fields.
Solution Approach 2:
The integrated rotor position sensor performs multiple functions simultaneously: it provides primary angular position measurement, redundant measurement for reliability, interference detection, and error correction. The evaluation unit processes both sensor signals to determine operational mode, enabling the system to maintain full measuring range while achieving redundancy through multi-functional operation rather than separate sensor systems.
3Object-affected harmful factors
If multiple sensor systems operating according to different physical principles are used, then interference resistance improves, but device complexity increases
Solution Approach 1:
The patent combines a magnetic field sensor and an inductive sensor into a single integrated rotor position sensor. The magnetic field sensor detects the magnetic field from the rotor magnet, while the inductive sensor detects changes in inductance caused by the rotor magnet's position. This merging of two different sensing principles allows the system to cross-validate measurements and reject interfering signals, thereby maintaining measurement precision while reducing susceptibility to stray magnetic fields.
Solution Approach 2:
The integrated rotor position sensor performs multiple functions simultaneously: it provides primary angular position measurement, redundant measurement for reliability, interference detection, and error correction. The evaluation unit processes both sensor signals to determine operational mode, enabling the system to maintain full measuring range while achieving redundancy through multi-functional operation rather than separate sensor systems.
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
Enhances the functional and operational reliability of rotor position sensors by minimizing interference and increasing redundancy, enabling accurate angular position determination even in challenging electromagnetic environments, suitable for autonomous vehicles.
Implementation Method 1
A magnetic field from at least one magnet rigidly connected to the rotor shaft is detected by a magnetic field sensor, for example, a Hall, AMR, or GMR sensor
Implementation Method 2
at least one electrically conductive area, bounded in a circumferential direction surrounding the sensor magnet, is provided on the sensor element for inductive interaction with a coil system arranged on the circuit carrier to generate a second sensor signal
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a rotor position sensor (10) for determining the angular position of a rotor shaft of an electric motor, comprising: - a indicating element (11) which can be fastened to an end of the rotor shaft and has at least one centrally arranged indicating magnet (12); and - at least one magnetic field sensor which can be positioned, opposite the indicating magnet (12) in extension of the motor shaft, on a circuit carrier (13) and which is designed to output a first sensor signal according to the angular position of the indicating element (11), wherein at least one electrically conductive region (15), which is delimited in a peripheral direction extending around the indicating magnet (12), is provided on the indicating element (11) for inductively interacting with a coil system (16) arranged on the circuit carrier (13), in order to generate a second sensor signal according to the angular position of the indicating element (11). The invention also relates to a steering system for a motor vehicle, comprising the rotor position sensor (10) according to the invention.