Magnetic Field Sensor Diagnostic Unit for Drift-Tolerant Functional Diagnosis
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Solution Overview
Problem
Current methods for functional diagnosis of magnetic field sensors in differential magnetic field measuring systems often require interruption of measurement operations and are sensitive to diagnostic current drift, making them inefficient and costly, especially in applications like electric bicycles where precision and cost-effectiveness are crucial.
Innovation Solution
A method using a magnetic field sensor diagnostic unit that generates diagnostic signals with different values to detect measurement signals from multiple sensors, forming differences to determine sensor properties without exact diagnostic current measurement, allowing for uninterrupted and drift-tolerant functional diagnosis using the same measuring axes and eliminating diagnostic magnetic fields from measurement signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If functional diagnosis of magnetic field sensors is performed using conventional methods, then measurement precision can be maintained, but measurement operation must be interrupted and high-precision driver devices are required
Solution Approach 1:
The patent applies periodic action by using alternating current signals at different frequencies (first frequency and second frequency) to diagnose magnetic field sensors. The diagnostic unit switches between different signal frequencies to elicit different responses from the sensors, enabling diagnosis without interrupting the measurement operation. This periodic signal switching allows the system to perform diagnostic functions while maintaining continuous measurement capability.
Solution Approach 2:
The patent introduces an intermediary approach by using a diagnostic unit that sends test signals through the signal conductor to the magnetic field sensors. This intermediary diagnostic unit can inject test signals without disrupting the main measurement function, allowing functional diagnosis to be performed concurrently with measurement operations through the same signal conductor infrastructure.
2Measurement precision
If high-precision driver devices are used to minimize diagnostic current drift, then measurement precision is maintained, but device complexity and cost increase
Solution Approach 1:
The patent applies parameter changes by varying the frequency of the diagnostic current signals rather than relying on precise amplitude control. The diagnostic unit sends test signals at different frequencies (first frequency for initial diagnosis, second frequency for verification) to the magnetic field sensors. This frequency-based approach eliminates the need for high-precision driver devices to maintain constant current amplitude, as the diagnostic information is extracted from frequency responses rather than amplitude measurements.
Solution Approach 2:
The patent substitutes the conventional approach of using high-precision current measurement systems with a frequency-based diagnostic method. Instead of measuring and controlling diagnostic current amplitude with high precision, the system uses frequency modulation and frequency response analysis to diagnose sensor functionality. This substitution replaces complex precision measurement infrastructure with simpler frequency-based signal processing.
3Adaptability or versatility
If diagnostic current drift occurs due to temperature changes, then functional diagnosis can still be performed, but measurement precision deteriorates
Solution Approach 1:
The patent uses periodic action with frequency-varying test signals to diagnose magnetic field sensors while being tolerant of temperature-induced current drift. By switching between different signal frequencies, the system can identify sensor characteristics based on frequency response patterns rather than absolute current values, making the diagnosis adaptable to temperature variations and maintaining functionality despite drift conditions.
Solution Approach 2:
The patent implements feedback by having the diagnostic unit analyze the response of magnetic field sensors to frequency-varying test signals and adjust subsequent diagnostic operations accordingly. The system monitors sensor responses at different frequencies and uses this feedback information to determine sensor functionality, compensating for temperature drift effects through adaptive diagnostic procedures.
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 continuous functional diagnosis of magnetic field sensors without interrupting measurement operations and is tolerant of diagnostic current drift, reducing the need for high-precision driver devices and allowing for cost-effective implementation, while compensating for magnetic interference and detecting sensor malfunctions.
Implementation Method 1
generating a first diagnostic magnetic field signal by means of a first diagnostic current in a first signal conductor; generating a second diagnostic magnetic field signal by means of a second diagnostic current in a second signal conductor
Implementation Method 2
acquiring a first measurement signal by means of a first measurement by a first magnetic field sensor with a first measuring axis and by means of a second magnetic field sensor with a second measuring axis
Implementation Method 3
calculating a first difference between the second measurement signal and the first measurement signal of the first magnetic field sensor; and calculating a second difference between the second measurement signal and the first measurement signal of the second magnetic field sensor
Data Source
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AI summary
The present invention relates to a method (100) for functional and/or fault diagnosis of magnetic field sensors in a differential magnetic field measurement system, in particular without interrupting the measurement operation and with tolerance to diagnostic current drift, by means of a magnetic field sensor diagnostic unit (10), comprising the steps: - generating (S1) a first signal with a first value in a signal conductor (14), - acquiring (S2) a first measurement signal by means of a first measurement by a first magnetic field sensor (20) with a first measuring axis (22) and by a second magnetic field sensor (26) with a second measuring axis (28), wherein the first measuring axis (22) and the second measuring axis (28) have essentially the same relative position (30), - generating (S3) a second signal with a second value in the signal conductor (14),- Acquiring (S4) a second measurement signal each by means of a second measurement by the first magnetic field sensor (20) and by the second magnetic field sensor (26), - Establishing (S5) a first difference between the second measurement signal and the first measurement signal of the first magnetic field sensor (20) and establishing (S9) a second difference between the second measurement signal and the first measurement signal of the second magnetic field sensor (26), - Determining (S6) at least one property of the first magnetic field sensor (20) and/or the second magnetic field sensor (26) based on the first difference and the second difference.