Current Sensor Calibration Using Automated Phase and Gain Correction
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Solution Overview
Problem
Calibrating Rogowski coil sensor systems is time-consuming, hazardous, and prone to inaccuracies due to manual phase and gain calibration processes, which are not scalable and expose technicians to high voltage and current.
Innovation Solution
A method and system for automated 'one-touch' calibration using a microcontroller and analog-to-digital converters to calculate and adjust preload parameters and scaling factors, reducing phase shifts and amplitude variations, and eliminating manual characterization steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual phase and gain calibration is performed, then calibration accuracy can be achieved, but calibration time increases and safety risks increase due to exposure to high voltage and current
Solution Approach 1:
The system performs self-calibration by automatically comparing sensor measurements against known test source values and computing correction factors without requiring manual intervention. The microcontroller executes calibration algorithms that adjust phase and gain parameters based on measured deviations, enabling the system to calibrate itself safely and efficiently.
Solution Approach 2:
The patent replaces manual mechanical calibration procedures with automated electronic calibration. Instead of physically adjusting components and manually measuring phase/gain, the system uses digital signal processing and microcontroller-based algorithms to automatically compute and apply calibration corrections, eliminating the need for technician exposure to hazardous conditions.
2Reliability
If manual characterization steps are performed, then sensor system accuracy can be verified, but the process becomes hazardous and not scalable
Solution Approach 1:
The sensor system automatically verifies its own accuracy by comparing measurements against known test source values. The microcontroller executes algorithms that compute expected values based on test source characteristics and compare them with actual sensor readings, automatically identifying and correcting deviations without requiring external manual verification.
Solution Approach 2:
The calibration system is designed to be universally applicable across multiple sensor types and configurations. The same automated calibration algorithm can calibrate different Rogowski coil sensors and other current sensors by adjusting parameters such as test source frequency and amplitude, enabling scalable deployment without requiring separate manual calibration procedures for each sensor type.
3Productivity
If automated calibration is implemented, then calibration time is reduced and safety is improved, but system complexity increases due to additional electronic components and algorithms
Solution Approach 1:
The microcontroller serves as an intermediary that coordinates between the test source, ADCs, and calibration algorithms. It manages the calibration sequence by triggering test source operation, acquiring ADC measurements, executing calibration computations, and applying correction factors, thereby orchestrating the automated calibration process without requiring complex external control systems.
Solution Approach 2:
The patent combines multiple functions into integrated components: the microcontroller integrates calibration control, data acquisition, and computation functions; the ADCs are shared between normal operation and calibration modes; the test source serves both measurement and calibration purposes. This merging reduces overall system complexity compared to having separate dedicated systems for each function.
Data Source
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AI summary
A system and method for phase and gain calibration of a current sensor system (11). The system comprises a microcontroller (22) configured to execute software in an energy measurement component (23) and a calibration computer (12) having a calibration application (24). The energy measurement component (23) receives first and second digital signals representing current and voltage signals, respectively, received from a test source (10), and calculates active power and a power factor, and provides those values to the calibration computer (12). The power factor is converted to a converted phase angle. Based on the information received from the energy measurement component (23), the calibration application (24) calculates parameters used to update components within the microcontroller (22) to maximize the accuracy of the current sensor system (11).