Nested Coil Pair Compensation for High-Frequency Current Sensors
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Solution Overview
Problem
Field-based current sensors experience a decline in accuracy at higher frequencies due to a decrease in coupling factor between the magnetic field produced by conductors and the magnetic field sensing elements.
Innovation Solution
A frequency-compensating current sensor utilizing a larger coil nested with a smaller coil, where induced current in the larger coil drives current in the smaller coil to generate a compensating magnetic field, enhancing the magnetic field sensing elements' sensitivity at higher frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If field-based current sensors are used, then current measurement capability is provided, but measurement accuracy deteriorates at higher frequencies due to decreased coupling factor
Solution Approach 1:
The patent employs a nested coil structure where a first coil is disposed within a second coil. The larger outer coil captures the ambient magnetic field generated by the current-carrying conductor, while the smaller inner coil generates a compensating magnetic field to counteract the frequency-dependent coupling degradation. This nested arrangement enables passive frequency compensation without requiring additional active components or increasing power consumption.
2Measurement precision
If passive frequency compensation is implemented using coil pairs, then measurement accuracy is maintained across wider frequency range, but device structure becomes more complex
Solution Approach 1:
The compensation system is self-powered, utilizing electromagnetic induction from the ambient magnetic field to generate the compensating signal. The first coil induces current that flows through the second coil, creating a compensating magnetic field without requiring external power sources or active electronic components. This self-service mechanism adds structural elements but avoids complex power management and control circuitry.
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 maintains accuracy and reliability of current measurement across a wider frequency range without increasing power consumption, utilizing passive compensation through coil pairs.
Implementation Method 1
As frequency of an ambient magnetic field (e.g., as produced by current flowing in a nearby conductor) increases, induced current in the larger coil increases, due to Faraday's law of induction.
Implementation Method 2
The induced current flowing through the large coil drives current in the smaller coil. The magnetic field generated by the current in the small coil consequently can compensate for reduced coupling factor
Data Source
AI summary
Systems, structures, circuits, and methods provide coil pairs that are used with magnetic-field type current sensors. Coil pairs, with a smaller coil nested within a larger coil, can be employed with or for magnetic field/flux sensors or sensing elements to compensate for the degradation in sensitivity as the frequency of the sensed current increases. A coil pair can be integrated into or on a substrate having a field-based current sensor. In use, frequency-dependent current is induced in a larger coil that is then driven through a smaller coil which concentrates a magnetic field on the sensitive element. The larger coil is configured to provide an increasing current as the frequency of the ambient magnetic field increases and provide the increasing current to the second coil to compensate for a frequency-dependent coupling factor between the magnetic field sensor and the ambient magnetic field.