Fluxgate Current Sensor With Multi-Sensor Interference Cancellation
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Solution Overview
Problem
Existing current sensors face challenges in accurately measuring current while effectively canceling extraneous magnetic field interference and achieving a high dynamic range, particularly due to limitations in sensitivity and saturation points.
Innovation Solution
The use of multiple fluxgate sensors arranged in a specific configuration to cancel higher-order magnetic interference, combined with strategic placement and separation of sensors to extend the dynamic range, and power-saving techniques such as shared excitation and compensation currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single fluxgate sensor is used for current sensing, then the sensor structure is simple, but the measurement precision is limited due to extraneous magnetic field interference and restricted dynamic range
Solution Approach 1:
The patent divides the sensing system into multiple fluxgate sensors (typically three sensors) arranged in a specific geometric configuration. Each sensor measures the magnetic field at a different position, and the individual measurements are processed to calculate the total current. This segmentation allows the system to cancel extraneous magnetic field interference while maintaining measurement precision across an extended dynamic range.
2Measurement precision
If multiple fluxgate sensors are used to cancel magnetic interference, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent combines multiple fluxgate sensors into a unified sensing system where the sensors are positioned in a specific geometric arrangement (e.g., triangular configuration). The magnetic field measurements from all sensors are merged through a calculation algorithm that computes the total current based on the vector sum of individual sensor readings. This merging approach cancels extraneous magnetic field interference while maintaining a relatively compact device structure.
3Measurement precision
If sensors are placed close to the current trace for high sensitivity, then the measurement precision improves, but the dynamic range is limited due to saturation at higher currents
Solution Approach 1:
The patent transitions from a single-point measurement approach to a distributed multi-point measurement system. By positioning multiple sensors at different spatial locations around the current trace and processing their measurements collectively, the system achieves both high sensitivity (through close proximity of individual sensors) and extended dynamic range (through the geometric arrangement and computational processing that prevents saturation effects from limiting the overall measurement range).
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
This approach results in a highly accurate, low-noise current sensor with extended dynamic range and reduced power consumption, capable of effectively canceling interference and maintaining measurement accuracy across a wider range of currents.
Implementation Method 1
An alternating electric current is passed through one coil, driving the core through an alternating cycle of magnetic saturation; i.e., magnetized, unmagnetized, inversely magnetized, unmagnetized, magnetized, and so forth.
Implementation Method 2
This constantly changing field induces an electric current in the second coil, and this output current is measured by a detector.
Implementation Method 3
when the core is exposed to a background field, it will be more easily saturated in alignment with that field and less easily saturated in opposition to it. Hence the alternating magnetic field, and the induced output current, will be out of step with the input current.
Data Source
AI summary
Operating a current sensor by conducting a current serially through a first region and a second region of an electrically conductive member. A first magnetic field produced by the current in the first region is sensed using a first magnetic field based current (MFBC) sensor having a first sensitivity. The sensitivity of a second MFBC is reduced. A second magnetic field produced by the current in the second region is sensed using the second MFBC sensor having a reduced sensitivity, in which the reduced sensitivity is lower than the first sensitivity. A magnitude of the current is calculated based on the first magnetic field and the second magnetic field. A dynamic range of the current sensor is extended by calculating a magnitude of the current using the second magnetic field after the first MFBC is saturated.