Variable Differential Transformer Fault Detection via Sum Voltage
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Solution Overview
Problem
Existing variable differential transformers face challenges in accurately detecting shorts across secondary coils, particularly in harsh environments like the aerospace industry, where precise position measurements are critical and faulty readings can lead to inaccurate data.
Innovation Solution
A system with a primary coil and at least one secondary coil wound in a series-aiding configuration around a moveable magnetic core, where a controller performs a built-in-test by sampling voltages across the secondary coil's side lines and center-tap to detect faults, utilizing a sum voltage comparison to determine if a fault has occurred, with the secondary coil wound in one continuous direction to enhance short detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If typical short circuit detection interfaces are used, then the device structure remains simple, but detecting shorts across secondary coils becomes difficult and unreliable
Solution Approach 1:
The system uses its own operational characteristics (voltage measurements during normal operation) to detect faults. The controller measures voltages at the secondary coil terminals and center tap, then determines faults by analyzing whether the sum of terminal voltages equals zero. This self-diagnostic approach enables reliable fault detection without adding external detection hardware or complex interfaces.
Solution Approach 2:
The controller continuously monitors the voltage relationship between secondary coil terminals and center tap, comparing the measured sum voltage against the expected zero value. This feedback mechanism allows the system to detect shorts across secondary coils by identifying when the voltage sum deviates from zero, providing reliable fault detection through continuous electrical feedback during operation.
2Measurement precision
If the secondary coil is wound in traditional configurations, then manufacturing is simpler, but short detection across the coils becomes inaccurate
Solution Approach 1:
The patent changes the electrical configuration parameter of the secondary coil from traditional separate windings to a series-aiding configuration where both secondary coils are wound in the same direction. This parameter change ensures that during normal operation, the voltages at the terminals are equal and opposite, making their sum zero. When a short occurs, this relationship breaks down, enabling precise short detection while maintaining straightforward manufacturing 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
This configuration allows for improved fault detection in variable differential transformers, particularly in 5-wire and 6-wire systems, by collapsing voltages during faults to near zero, making it easier for the controller to identify issues, thus ensuring accurate position measurements and preventing faulty data from being recorded.
Implementation Method 1
At least one secondary coil is wound around the moveable magnetic core in one continuous direction and magnetically coupled with the primary coil
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
In accordance with at least one aspect of this disclosure, a system can include a primary coil (112) wound around a moveable magnetic core (108), at least one secondary coil (118, 218a, 218b) wound in one continuous direction and magnetically coupled with the primary coil (112), and a controller (126) operatively connected to determine a position of the moveable magnetic core (108) and configured to detect a fault across the secondary coil (118, 218a, 218b).