Current-measuring device with compensation coil and magnetic sensors
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Solution Overview
Problem
Conventional current-measuring devices using ferromagnetic or ferrimagnetic flux concentrators suffer from high sensor weight and magnetic hysteresis-induced measuring errors, limiting precision and sensitivity to interference fields.
Innovation Solution
A current-measuring device employing multiple magnetic-field sensors arranged around an electrical conductor, with a compensation coil and a controller to set a compensation current, minimizing the magnetic field detected by sensors and allowing precise current measurement over a wide range with reduced sensitivity to interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a ferromagnetic or ferrimagnetic flux concentrator is used to concentrate magnetic field lines, then the magnetic field detection capability is improved, but the sensor weight increases and magnetic hysteresis errors occur
Solution Approach 1:
The patent removes the ferromagnetic or ferrimagnetic flux concentrator from the measurement system entirely. Instead of using a physical flux concentrator, the invention uses multiple magnetic field sensors arranged around the conductor to detect the magnetic field, thereby eliminating the weight problem while maintaining measurement capability.
Solution Approach 2:
The patent replaces the mechanical/physical flux concentrator structure with an electronic measurement approach using multiple sensors and signal processing. The magnetic field concentration function is achieved through the geometric arrangement of sensors and mathematical evaluation rather than physical concentration.
2Measurement precision
If a ferromagnetic or ferrimagnetic flux concentrator is used to concentrate magnetic field lines, then the magnetic field detection capability is improved, but magnetic hysteresis-induced measuring errors occur
Solution Approach 1:
The patent extracts and removes the ferromagnetic or ferrimagnetic flux concentrator that causes hysteresis errors. By using air or non-magnetic material instead, the system eliminates the hysteresis effect entirely while maintaining magnetic field detection through multiple sensors arranged around the conductor.
Solution Approach 2:
The patent replaces the problematic ferromagnetic material with simple air or non-magnetic material that has no hysteresis properties. This substitution uses a 'simpler' medium that, while not concentrating flux, avoids the measurement errors entirely.
3Weight of stationary object
If multiple magnetic-field sensors are arranged around the electrical conductor without a flux concentrator, then the sensor weight is reduced and hysteresis errors are avoided, but the measurement precision may be compromised
Solution Approach 1:
The patent divides the measurement task among multiple magnetic field sensors arranged around the conductor at different positions. Each sensor measures the magnetic field at its location, and the controller evaluates these multiple measurements to determine the total current, achieving both weight reduction and maintained precision.
Solution Approach 2:
The patent transitions from a single-point measurement approach to a multi-dimensional measurement approach by arranging sensors around the conductor in space. The controller uses the spatial distribution of magnetic field measurements to calculate the current, adding spatial dimensionality to the measurement process.
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 precise and interference-resistant measurement of high electric currents with a lightweight device, avoiding magnetic hysteresis errors and maintaining accuracy across a large measuring range.
Implementation Method 1
a magnetic field induced about an electric conductor by the electric current may be detected and evaluated
Implementation Method 2
a compensation coil (20) arranged around the electrical conductor (2), wherein the plurality of magnetic-field sensors (10-i) are arranged in the interior of the compensation coil (20)
Data Source
AI summary
The present disclosure relates to electrical conductors. The teachings herein may be embodied a current-measuring devices and/or methods for determining an electric current in an electrical conductor. For example, a method for determining a magnitude of an electric current in an electrical conductor may include: measuring output signals from a plurality of magnetic-field sensors arrayed around the electrical conductor; setting a compensation current through a compensation coil surrounding the plurality of magnetic-field sensors based on detected output variables of the magnetic-field sensors; and determining the magnitude of the electric current through the electrical conductor based on the set compensation current through the compensation coil.