Current Measurement Device Using Cascaded Opposing Field Windings
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Solution Overview
Problem
Current current measurement systems face challenges in achieving continuous measurement with high resolution and large measuring range due to slow switching times, limited sub-ranges, and low flexibility, especially when dealing with direct current and external magnetic field interference.
Innovation Solution
A measuring device with a primary winding unit and an opposing field winding unit, where the opposing field windings are connected magnetically in series, allowing for stepless current measurement by compensating the primary magnetic field with a cascading second current, enabling high-resolution measurement across a wide range without shunts and maintaining consistency across all sub-ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If switching between shunts is used to extend measuring range, then measuring range is increased, but switching time causes loss of rapid current changes and peaks
Solution Approach 1:
The measuring device divides the opposing field winding into multiple segments (first opposing field winding, second opposing field winding, etc.), each handling a specific current range. This allows simultaneous operation of multiple segments without switching, eliminating switching time loss while maintaining extended measuring range.
Solution Approach 2:
The patent implements continuous measurement capability by having multiple opposing field windings operate simultaneously without interruption. The cascaded configuration ensures that as one winding reaches its current threshold, another winding immediately takes over, providing continuous coverage without gaps or switching delays.
2Quantity of substance
If multiple opposing field windings are used to extend measuring range, then measuring range is increased, but device complexity increases
Solution Approach 1:
The patent combines multiple opposing field windings in a cascaded configuration where they share common magnetic path and control circuitry. This merging approach allows extended measuring range while minimizing additional complexity through shared resources and integrated design.
Solution Approach 2:
Each opposing field winding serves multiple functions: it provides compensation for its specific current range, contributes to the overall magnetic field cancellation, and can operate in conjunction with other windings. This multi-functionality reduces the need for separate dedicated components for each measurement range.
3Quantity of substance
If automatic switching between sub-ranges is implemented, then measuring range is increased, but resolution becomes non-constant across sub-ranges
Solution Approach 1:
The patent assigns specific current thresholds to each opposing field winding based on its position in the cascade. Each winding is optimized for its specific current range with appropriate turn ratios and threshold settings, ensuring constant resolution across the entire measuring range while maintaining local optimization for each segment.
4Measurement precision
If Hall elements are used in air gaps to measure magnetic flux density, then current measurement is achieved, but external magnetic fields falsify the measurement
Solution Approach 1:
The patent employs opposing field windings that generate compensating magnetic fields to counteract the primary magnetic field before external interference can affect the measurement. This preliminary anti-action neutralizes the magnetic field in the measurement region, making the system immune to external magnetic field interference.
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
The solution enables continuous, high-resolution current measurement over a large range with high linearity and dynamics, eliminating the need for shunts and maintaining consistent resolution, suitable for both direct and alternating currents, and can be implemented cost-effectively by modifying existing current transformer systems.
Implementation Method 1
a primary winding unit (2) which can be fed with a first current (IP) to form a first magnetic field
Implementation Method 2
an opposing field winding unit (3) which can be fed with a second current (IS) to form a second magnetic field that at least partially compensates for the first magnetic field
Implementation Method 3
a magnetic field measuring device (4) with which a total magnetic field formed by the primary winding unit (2) and the opposing field winding unit (3) is detected
Data Source
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AI summary
The present invention relates to a measuring device comprising a primary winding unit that can be supplied with a first current to generate a first magnetic field, a counter-field winding unit that can be supplied with a second current to generate a second magnetic field that at least partially compensates for the first magnetic field, and a magnetic field measuring device for detecting a total magnetic field generated by the primary winding unit and the counter-field winding unit. The invention further relates to a corresponding measuring method.According to the invention, the counter-field winding unit has n individual counter-field windings magnetically connected in series to each other, wherein n is a natural number and ≥ 2, and the measuring device has a power supply and limiter circuit device coupled to the magnetic field measuring device, with which the counter-field windings are successively supplied with the second current up to a current threshold value assigned to the respective counter-field winding unit, wherein each of the counter-field windings implements one of n partial measuring ranges.