Analog Voltage Readout with Online Self-Calibration
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Solution Overview
Problem
Existing readout electronics for analogue voltage signals in power transmission and distribution lack the ability to perform self-calibration without interrupting the current path, necessitating manual interaction and offline calibration, which reduces availability and increases manual intervention.
Innovation Solution
An arrangement that superimposes a modulated reference voltage onto the analogue voltage signal, allowing for online self-calibration by using superposition means with modulation and switching mechanisms operating at frequencies significantly higher than the ADC sampling frequency, enabling concurrent signal processing and calibration without information loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual calibration is performed by switching the input signal from the analogue voltage signal to the reference voltage, then the gain error can be corrected, but the measurement process is interrupted and availability is reduced
Solution Approach 1:
The patent combines the reference voltage signal and the analogue voltage signal into a single composite signal that is continuously fed to the ADC. This merging allows both calibration and measurement to occur simultaneously without interrupting the measurement process, resolving the contradiction between gaining accuracy through calibration and maintaining availability during measurement.
Solution Approach 2:
The patent uses periodic modulation of the reference voltage signal at a frequency distinct from the measurement signal. This periodic action allows the system to periodically insert calibration references into the continuous measurement stream, enabling ongoing gain error correction without stopping the measurement process.
2Productivity
If the reference voltage is directly superimposed on the analogue voltage signal, then both signals can be processed concurrently, but signal separation and DC offset removal become difficult
Solution Approach 1:
The reference voltage is modulated periodically at a specific frequency before being superimposed on the analogue voltage signal. This periodic modulation creates distinct frequency components that can be easily separated using frequency-domain processing, solving the signal separation problem while maintaining concurrent processing capability.
Solution Approach 2:
The patent changes the frequency parameter of the reference voltage signal through modulation, transforming it from a DC or low-frequency signal into a high-frequency AC signal. This parameter change creates a clear frequency separation between the reference and measurement signals, simplifying subsequent separation and processing operations.
3Device complexity
If switching frequency is low, then the switching mechanism is simpler, but information loss occurs during signal transformation
Solution Approach 1:
The patent introduces modulation as an intermediary process between the reference voltage and the superposition stage. By modulating the reference voltage at a high frequency before switching/superimposing, the system ensures that the reference signal occupies a distinct frequency band that can be fully captured by the ADC, preventing information loss while maintaining relatively simple switching hardware.
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 uninterrupted measurement and calibration of readout electronics, ensuring high accuracy and stability over time, reducing manual interaction, and maintaining system availability by allowing online self-calibration without disrupting the analogue voltage signal.
Implementation Method 1
modulation means for generating a modulated reference voltage from the analogue reference voltage
Implementation Method 2
superimposing the modulated reference voltage onto the analogue voltage signal and for forwarding the combined analogue signal to the converting means for digitization
Data Source
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AI summary
An arrangement for reading out an analogue voltage signal (Vin) comprises a voltage signal input (I) for applying the analogue voltage signal (Vin) thereto, reference means (ref) for generating an analogue reference voltage (Vref) and converting means (ADC) for converting an analogue input signal (1 ) into a digital output signal (2). In order to enable online self calibration of the arrangement, the arrangement further comprises superposition means (sup) which are adapted to receive the analogue voltage signal (Vin) and the analogue reference voltage (Vref). The superposition means (sup) contain modulation means for generating a modulated reference voltage (Vmod) from the analogue reference voltage (Vref) and are adapted for generating a combined analogue signal (4) by superimposing the modulated reference voltage (Vmod) onto the analogue voltage signal (Vin) and for forwarding the combined analogue signal (4) to the converting means (ADC).