Inductive Sensor Open Circuit Detection via Star Point Voltage Monitoring
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Solution Overview
Problem
Inductive sensors face challenges in detecting open circuits at coils coupled in a star configuration, where the star point is inaccessible due to routing restrictions, safety requirements, and limited pins, which is critical for high-reliability applications like automotive safety.
Innovation Solution
The system employs comparators monitoring voltages at driving pins coupled to the coils, comparing them with reference voltages from voltage sources to detect open circuits, using a star configuration that allows detection without accessing the star point, and includes filters to prevent false positives from electromagnetic compatibility interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If coils are coupled in a star configuration with inaccessible star point, then routing restrictions and pin limitations are satisfied, but open circuit detection becomes difficult
Solution Approach 1:
The patent introduces voltage sources and comparators as intermediary components connected to the driving pins. These intermediaries enable indirect detection of open circuits by monitoring voltage levels at accessible points, eliminating the need to physically access the inaccessible star point while maintaining detection capability
Solution Approach 2:
The patent replaces direct physical access to the star point with an electrical measurement system. Instead of mechanically accessing the star point, voltage sources apply test signals and comparators electronically monitor the resulting voltage levels at driving pins, substituting a mechanical access problem with an electrical measurement solution
2Reliability
If voltage monitoring is implemented at driving pins, then open circuit detection capability is improved, but device complexity increases
Solution Approach 1:
The voltage sources and comparators serve multiple functions: they enable open circuit detection while simultaneously working alongside the coil driving circuitry. The same voltage sources can be used for both excitation and monitoring purposes, and the comparators provide both fault detection and signal conditioning functions, reducing the need for separate dedicated components
3Measurement precision
If filters are added to prevent false positives from electromagnetic interference, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent employs simple RC low-pass filters consisting of resistors and capacitors, which are inexpensive and compact components. These filters effectively suppress high-frequency electromagnetic interference while adding minimal complexity to the overall circuit design
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 reliable open circuit detection concurrently with position sensing, maintaining sensor accuracy and not increasing electromagnetic radiation, and is scalable for high-speed sensors with many coils.
Implementation Method 1
inductive sensors may be used to measure position, distance, and speed, especially of conductive objects
Implementation Method 2
one or more comparators coupled to the driving pins that monitor the voltages of the driving pins to detect open circuits
Data Source
AI summary
A system for open circuit detection for inductive sensors includes coils coupled in a star configuration on a first side of each coil. The system further includes driving pins coupled to the coils on a second side of each coil and voltage sources coupled to the driving pins. The system further includes one or more comparators coupled to the driving pins that monitor the voltages of the driving pins to detect open circuits.