Multi-phase Current Measurement Transfer Function Compensation
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Solution Overview
Problem
Current measurement technologies face challenges in accurately measuring current in multi-phase electricity supplies due to differences in transfer functions between phases, leading to imbalanced measurements and requiring additional independent equations to correct for these mismatches.
Innovation Solution
A current measurement apparatus and method that determines transfer function ratios between phases using a data processor and applies Kirchhoff's law, allowing for the estimation and compensation of mismatches, thereby improving the accuracy of load current measurement in multi-phase systems without the need for multiple measurement transducers per phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current measurement is performed using conventional transducers in multi-phase systems, then current values can be obtained, but measurement accuracy deteriorates due to transfer function mismatches between phases
Solution Approach 1:
The system uses feedback by measuring the sum of currents in all phases and using this information to adjust individual phase current measurements. The measured sum current is compared with the calculated sum from individual phase measurements, and correction factors are applied to improve accuracy of subsequent measurements.
Solution Approach 2:
The system dynamically adjusts transfer function parameters for each phase based on measured discrepancies. By changing the transfer function parameters adaptively rather than using fixed values, the system compensates for mismatches between phases and improves measurement accuracy over time.
2Measurement precision
If multiple measurement transducers are used per phase to compensate for mismatches, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The system makes a single measurement transducer perform multiple functions by using it to measure both the phase current and contributing to the sum current measurement. This multi-functionality eliminates the need for additional transducers while maintaining measurement accuracy through the feedback mechanism.
Solution Approach 2:
The system merges the measurement functions by combining the individual phase current measurements with the sum current measurement into a unified measurement approach. This integration allows the system to use the same physical transducers for multiple measurement purposes, reducing hardware requirements.
3Device complexity
If transfer function mismatches are not compensated, then device complexity remains low, but measurement reliability deteriorates due to imbalanced measurements
Solution Approach 1:
The measurement system performs self-correction by automatically detecting transfer function mismatches through sum current measurement and adjusting its own transfer function parameters accordingly. This self-service capability improves measurement reliability without requiring external calibration equipment or complex intervention systems.
Data Source
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AI summary
A measurement circuit is arranged to make several measurements, either at different times or in respect of different frequency components of currents measured by current sensors in respective phases of a multiphase supply system. The measurments are then used to correct for discrepencies in the transfer function of the sensors.