Electronic Transformer Calibration Using Dominant Pole Filtering
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Solution Overview
Problem
Existing methods for calibrating the cut-off frequency of electronic transformers are inadequate for achieving precise measurements across a wide frequency range due to deviations in actual capacitance or resistance from nominal values, leading to errors in calculated cut-off frequencies.
Innovation Solution
A method and apparatus that determine amplitudes and phase angles of sampled signals at different frequencies, calculate an amplitude gain factor and time constant, and configure a dominant pole and amplitude factor for the digital signal processing unit to improve measurement precision by adapting to a wide frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the cut-off frequency is calculated based on the nominal value of the component in the signal acquisition unit, then the calculation is simple, but there is a deviation between the calculated cut-off frequency and the actual cut-off frequency, resulting in a large error of the measured current or voltage
Solution Approach 1:
The patent changes the parameter used for cut-off frequency calculation from the nominal component value to the actual resonant frequency obtained through impedance spectrum analysis. This parameter change eliminates the deviation caused by component tolerance while maintaining a relatively simple calculation process based on the measured resonant frequency.
2Ease of manufacture
If a same clock source signal and a same current or voltage input signal are used for calibration, then the calibration process is established, but the existing method cannot meet the requirement for measurement precision in a wide frequency range
Solution Approach 1:
The patent introduces dynamic frequency sweeping to obtain the impedance spectrum across a wide frequency range, rather than using a fixed frequency calibration method. This dynamic approach allows the system to adapt to different operating frequencies by identifying the actual resonant frequency, thereby improving frequency range adaptability while maintaining an established calibration process.
3Ease of operation
If the digital signal processing unit calculates the measured current or voltage based on the cut-off frequency, then the measurement process is straightforward, but the deviation in cut-off frequency causes large measurement errors
Solution Approach 1:
The patent performs preliminary impedance spectrum analysis to determine the actual resonant frequency before the measurement process. This preliminary action establishes the accurate cut-off frequency in advance, ensuring both measurement process simplicity and high measurement accuracy during actual operation.
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
Ensures accurate measurement of primary currents and voltages by correcting the impact of analog components within an allowable error range, enhancing precision to meet class 0.2 precision requirements without needing clock synchronization, and reducing system complexity and costs.
Implementation Method 1
The induction unit generates an induction signal based on a to-be-measured current or voltage using electromagnetic induction
Data Source
AI summary
An electronic transformer calibration method includes: obtaining amplitudes and phase angles of sampled signals obtained by a tested signal acquisition unit by sampling different frequency signals, where the tested signal acquisition unit is a signal acquisition unit included in an electronic transformer to be calibrated; determining an amplitude gain factor and a time constant of the tested signal acquisition unit; determining a dominant pole and an amplitude factor of the tested signal acquisition unit; and configuring the dominant pole and the amplitude factor for a digital signal processing unit included in the electronic transformer to be calibrated, so that the digital signal processing unit performs digital filtering on an input signal based on the dominant pole and the amplitude factor, to obtain an output signal. The input signal is obtained by performing analog-to-digital conversion on a signal output by the tested signal acquisition unit.