DC Component Measurement in Clipped Current Signals
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Solution Overview
Problem
Conventional methods for determining the DC component value in signals with high AC components that exceed the measurement range of current sensors result in incorrect readings due to saturation or clipping, leading to costly solutions or reduced sensor accuracy.
Innovation Solution
A method involving a current sensor placed around a magnetic core with a gap, detecting signal zero crossings, calculating a time error indicator, and using integration to determine the DC component value, allowing for accurate measurement even when AC components exceed the sensor's range, and enabling the use of less expensive sensors with improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to determine DC component value by calculating mean value of the signal, then the measurement is simple and direct, but the measurement precision deteriorates when AC component magnitude is multiple times higher than DC component magnitude or when saturation/clipping occurs
Solution Approach 1:
The patent extracts and processes zero crossing events separately from the full signal. By identifying only the zero crossing points and their timestamps, the method isolates the critical information needed for DC component calculation, avoiding the need to process the entire high-amplitude AC signal that causes saturation issues
Solution Approach 2:
The patent replaces the conventional mathematical approach of calculating mean value of the full signal with a temporal analysis method based on zero crossing intervals. This substitution transforms the problem from signal amplitude analysis to time interval analysis, which is immune to AC component magnitude and saturation effects
2Adaptability or versatility
If sensor measurement range is increased to accommodate high AC component magnitude, then the sensor can measure both AC and DC components accurately, but the sensor cost increases or sensor accuracy decreases
Solution Approach 1:
The patent introduces zero crossing detection as an intermediary mechanism between the sensor and the DC component calculation. This intermediary extracts temporal information from the signal that is independent of amplitude, allowing accurate DC measurement without requiring the sensor to handle the full AC signal range
Solution Approach 2:
The patent substitutes amplitude-based measurement with time-based measurement. By measuring the time intervals between zero crossings rather than analyzing signal amplitudes, the system achieves DC component measurement that is unaffected by AC component magnitude or sensor saturation
3Reliability
If AC component is reduced in the signal measured by sensor, then saturation/clipping is avoided, but the solution becomes costly or sensor accuracy is reduced
Solution Approach 1:
The patent extracts zero crossing information directly from the raw signal without requiring any preprocessing or reduction of the AC component. This extraction approach maintains signal integrity while obtaining measurement data that is immune to saturation effects
Solution Approach 2:
The patent converts the presence of high-amplitude AC components, which traditionally cause saturation and measurement errors, into a useful signal特征. The zero crossing points of the AC signal contain embedded information about the DC component, transforming the problematic AC signal into a measurement resource
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 accurate DC component measurement without being limited by AC component levels, reducing costs and sensor size while maintaining high accuracy, and allowing for the characterization of maximum AC component magnitude.
Implementation Method 1
a current sensor placed in the gap... in a current-carrying wire, around which there is located a magnetic core provided with a gap, by using a current sensor placed in the gap
Data Source
Figure 1~3
AI summary
The present invention concerns the method of determination DC component value in clipped/saturated signals containing both AC and DC components. The method is applicable for signals obtained from current sensor (4) where only the DC component is fully reproduced and where AC component can be out of sensor's measurement range. The invented method comprises a step of detecting zero crossing event one by one, a step of determination a time error indicator terr, a step of determination of DC component value VDC using the time error indicator terr, a step of modification the DC component value in continuous way. The information about the DC component value is transferred to the user interface for a future analysis and for controlling.