Position Detection Module Phase Error Compensation
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Solution Overview
Problem
Existing position detection systems for gas turbines, such as those using linear variable differential transformers (LVDTs), often suffer from inaccuracies due to phase differences between feedback and excitation signals, leading to incorrect valve position calculations.
Innovation Solution
A method involving a position detection module with a controller that generates an excitation signal, samples feedback signals, and calculates device position based on multiple samples of both excitation and feedback signals, reducing phase-related inaccuracies by using digital-to-analog converters and analog-to-digital converters to enhance precision and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If LVDT is used to measure valve position by comparing instantaneous voltage values of feedback and excitation signals, then the measurement process is simple, but the position calculation becomes inaccurate due to phase differences between signals
Solution Approach 1:
The patent applies periodic action by using multiple excitation signals with different frequencies to periodically excite the LVDT. By sampling the feedback signal at multiple frequency points and performing spectral analysis, the system can identify the phase relationship more accurately. This periodic excitation approach transforms the single-point measurement into a multi-point analysis, resolving the phase ambiguity that causes measurement inaccuracy while maintaining operational simplicity through automated frequency sweeping.
Solution Approach 2:
The patent changes the frequency parameter of the excitation signal to resolve the phase difference problem. By varying the excitation frequency and observing the corresponding feedback signal characteristics, the system can determine the actual phase relationship between excitation and feedback signals. This parameter change approach allows accurate position calculation even when phase differences exist, thereby improving measurement precision without complicating the overall measurement process.
2Duration of action of stationary object
If phase difference between feedback and excitation signals is present, then the LVDT can operate continuously, but the calculated position becomes inaccurate
Solution Approach 1:
The patent enhances the feedback mechanism by not only using the LVDT feedback signal for position measurement but also by feeding back the phase information obtained through spectral analysis. This dual feedback approach allows the system to continuously operate the LVDT while compensating for phase differences in real-time. The phase correction feedback ensures that position calculation accuracy is maintained throughout continuous operation, resolving the contradiction between operational duration and measurement precision.
Solution Approach 2:
The patent applies preliminary action by performing spectral analysis and phase determination before using the feedback signal for position calculation. By pre-processing the signals to establish the phase relationship at each frequency point, the system eliminates phase-related errors before they affect position accuracy. This preliminary phase characterization enables continuous LVDT operation with consistently accurate position measurements throughout the measurement range.
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 improves the accuracy of valve position measurements by eliminating phase differences and providing more precise displacement calculations, enhancing the control of gas turbines.
Implementation Method 1
The LVDT provides a feedback signal in response to an external input excitation signal, the feedback signal is proportioned to the displacement of the valve
Data Source
AI summary
A method for measuring a position of a device which is connected to a position sensor is provided. The method includes the steps of controlling an excitation unit to generate an excitation signal which excites the position sensor to provide a first feedback signal proportioned to the displacement of the device, controlling a sampling unit to sample the first feedback signal and obtain a plurality of first feedback samples, and calculating the position of the device based at least in part on the first feedback samples.