Adaptive Filter Tracking for Rogowski Coil Measurement Accuracy
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Solution Overview
Problem
Process and temperature variations affect the position of poles in the transfer function of low pass filters used with transducers like Rogowski coils, leading to inaccuracies in current measurement circuits.
Innovation Solution
A filter apparatus with matched resistor and capacitor components, coupled with an analog-to-digital converter and a reference generator, adjusts the frequency response to compensate for changes in component values, ensuring stability over an operational frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a low pass filter is used to linearize the frequency response of a Rogowski coil, then measurement accuracy is improved, but process and temperature variations cause component value changes that affect pole position and reduce measurement stability
Solution Approach 1:
The patent implements a feedback mechanism where the actual pole position is continuously monitored and used to adjust the filter components. A microcontroller measures the actual cutoff frequency by analyzing the filter's response to test signals, then calculates correction factors to adjust resistor and capacitor values, closing the loop to maintain stable frequency response despite environmental variations
Solution Approach 2:
The patent dynamically changes the electrical parameters of the filter by adjusting resistor and capacitor values based on measured pole position. The microcontroller modifies component values in real-time to compensate for drift, transforming static filter components into dynamically adjustable elements that maintain optimal performance across varying conditions
2Stability of the object's composition
If matched resistor and capacitor components are used in the filter, then component value stability is improved, but additional tracking components and control circuitry increase device complexity
Solution Approach 1:
The microcontroller serves multiple functions: it monitors the filter's frequency response, calculates pole position deviations, determines correction factors, and controls the adjustment of filter components. This multi-functionality consolidates what would otherwise require separate dedicated circuits into a single intelligent controller, managing complexity while maintaining stability
Solution Approach 2:
The filter system performs self-diagnosis and self-correction by automatically monitoring its own pole position and adjusting its component values without external intervention. The microcontroller continuously measures the filter response, detects drift, and commands adjustments to maintain optimal performance, enabling the system to service itself
Data Source
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AI summary
Filters are made from real components, such as resistors and capacitors, and tolerances in their values significantly affect the way in which the filter modifies the signal passing through the filter. This disclosure relates to a way of addressing such problems.