Axial Distance Adjustment for Electric Machine Sensor Accuracy
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Solution Overview
Problem
Existing sensor devices for electric machines, such as those in motor vehicles, suffer from inaccuracies and measurement errors due to inhomogeneous magnetic fields and fluxes, leading to cyclic angle errors that affect torque accuracy, and current correction methods fail to account for changes in the axial distance between the signal sensor and generator, which are influenced by mechanical tolerances and temperature.
Innovation Solution
The sensor device captures the axial distance between the signal generator and sensor, using this information to correct angle estimation and determine torque, by employing a mechanical apparatus that adjusts the signal generator's position based on torque, allowing for precise angle estimation and torque calculation through signal evaluation and characteristic curve analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If signal sensor and signal generator are arranged at a fixed axial distance, then device structure is simple, but measurement precision deteriorates due to inhomogeneous magnetic fields and cyclic angle errors
Solution Approach 1:
The patent makes the axial distance between signal sensor and signal generator dynamically adjustable rather than fixed. The signal generator can be moved axially relative to the signal sensor to optimize the magnetic field homogeneity and minimize harmonic distortions, thereby improving angle estimation accuracy without significantly increasing device complexity
Solution Approach 2:
The patent changes the axial distance parameter between signal sensor and signal generator to optimize measurement precision. By adjusting this distance, the magnetic field distribution is improved and cyclic angle errors are reduced, while the adjustment mechanism keeps the overall device structure relatively simple
2Ease of operation
If axial distance changes are not compensated, then device operation is simple, but measurement precision deteriorates due to temperature and mechanical tolerance influences
Solution Approach 1:
The patent introduces a feedback mechanism where the actual axial distance between signal sensor and signal generator is continuously monitored and used to correct angle estimation. This compensation for temperature and mechanical tolerance influences improves measurement precision while maintaining relatively simple device operation through automated correction algorithms
Solution Approach 2:
The patent performs preliminary characterization of the magnetic field as a function of axial distance and stores correction data. During operation, pre-stored correction factors are applied based on the measured axial distance, improving measurement precision without requiring complex real-time calculations that would complicate device operation
3Measurement precision
If mechanical apparatus adjusts signal generator position, then angle estimation precision improves, but device complexity increases
Solution Approach 1:
The patent integrates the axial adjustment mechanism within the existing sensor device structure. The signal generator is mounted on an adjustable carrier that can move axially relative to the signal sensor, with the adjustment mechanism nested within the housing. This improves angle estimation precision through optimized magnetic field coupling while minimizing increases in device complexity through compact integration
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 approach ensures improved angle estimation with reduced amplitude errors and accounts for changes in axial distance, enabling accurate torque determination without additional sensors, thus stabilizing electric machine operation and reducing computational complexity.
Implementation Method 1
a signal generator that is joined non-rotatably to the rotor shaft and is arranged axially on the end face of the rotor shaft
Implementation Method 2
inductive angle sensors on the basis of decoupled coils or sensor apparatuses that are based on the eddy current effect
Implementation Method 3
an apparatus that is designed to axially displace the signal generator depending on a torque of the electric machine acting on the rotor shaft
Data Source
AI summary
A sensor device for an electric machine includes a rotor shaft mounted rotatably in a housing, with a signal generator that is or can be joined non-rotatably to the rotor shaft and is or can be arranged axially on the end face of the rotor shaft. A signal sensor is fixed to the housing opposite on the end face of the signal generator and at a distance from the signal generator. The signal sensor acquires an axial distance from the signal generator.