Inductive Rotation Angle Sensor with Redundant Flat Coils
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Solution Overview
Problem
Existing inductive rotation angle detection methods for electrical machines lack precision and redundancy, particularly in electromobility applications, where accurate rotor position measurement is crucial to prevent damage from 'locked rotor' conditions.
Innovation Solution
A sensor arrangement using multiple flat coils arranged around the axis of rotation, with an evaluation device determining inductance changes to calculate the angle of rotation, providing redundancy for reliable detection even if one coil fails, and allowing flexible calibration for various applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single coil or fewer coils are used for rotation angle detection, then the device complexity is reduced, but the reliability and measurement precision deteriorate due to lack of redundancy
Solution Approach 1:
The detection system is segmented into multiple independent coil groups, where each coil group contains at least two flat coils arranged at different angular positions. This segmentation allows the system to maintain reliable operation even if individual coils fail, as other coils in the same or different groups can compensate, thereby improving detection reliability without requiring a fully redundant complex system.
Solution Approach 2:
Multiple flat coils within each coil group are merged in terms of their functional output, where the evaluation device processes signals from multiple coils to determine a single rotation angle. This merging approach consolidates the detection capability while maintaining redundancy, as the system can evaluate rotation angle based on combined information from multiple coils rather than requiring separate complete detection paths.
2Measurement precision
If more flat coils are arranged around the rotation axis, then the measurement precision and reliability improve through redundancy, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Rather than uniformly distributing all coils around the entire rotation axis, the patent applies local quality by arranging coils in specific angular positions within limited angular ranges. Each coil group covers a specific angular range with coils positioned to optimize detection for that local region, which simplifies manufacturing compared to a fully uniform distribution while maintaining measurement precision through strategic local placement.
Solution Approach 2:
The system uses multiple coils within each coil group to provide redundancy beyond the minimum single-coil requirement, but not to the extent of placing coils at every possible angular position. This partial redundancy approach ensures that even if one or two coils fail, the remaining coils in the group can still provide accurate measurement, achieving sufficient reliability without the manufacturing complexity of a complete redundant system.
3Reliability
If coil groups with multiple flat coils are used, then redundancy is achieved for reliable detection, but the device complexity and space requirements increase
Solution Approach 1:
Multiple flat coils within each coil group are arranged in a nested or compact configuration around the rotation axis, where coils are positioned at different radial distances or angular offsets but within a limited axial and radial space. This nested arrangement allows multiple coils to occupy a compact volume, achieving redundancy without proportionally increasing the overall sensor space requirements.
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
Enables precise and reliable detection of the rotor's angle of rotation, preventing damage to electrical machines by accurately determining the rotor position and allowing for flexible application in different scenarios, including full 360° rotation measurement.
Implementation Method 1
the flat coils are shaped in such a way that a current inductance of each flat coil depends on the current angle of rotation of the flux element
Implementation Method 2
an electrically conductive element arranged such that the time-varying magnetic field generates eddy currents therein
Data Source
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AI summary
The invention relates to a sensor arrangement (105) for detecting a rotational angle (D) of a flux element (125) on a circular path (130) about a rotational axis (155). The sensor arrangement contains the flux element (125) and coil groups (165a-c) having flat coils (160a-i) in the same rotational angle region (Wa-c) on a plane (120) concentric with the rotational axis (155) in parallel with the circular path (130), the inductance (La-i) of the flat coils (160a-i) being dependent on the rotational angle (D) of the flux element (125). The sensor arrangement also has an evaluation device (145) for evaluating the inductance (La-i) and individual rotational angle (Ea-i) of the flux element (125) for each flat coil (160a-i) and the rotational angle (D) from at least two matching individual rotational angles (Ea-i). In an electric machine (100) comprising the sensor arrangement (105), the flux element (125) is coupled to the rotor (185) and the coil groups (165a-c) are coupled to the stator (180), or vice versa. In a method for detecting the rotational angle (D), the inductance (La-i) and the individual rotational angle (Ea-i) is determined for each flat coil (160a-i), and the rotational angle (D) is provided on the basis of at least two matching individual rotational angles (Ea-i).