Offset Current Sensor Layout for Stray Field Immunity
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Solution Overview
Problem
Current sensors struggle to provide consistent and accurate current measurements in environments with stray magnetic fields and for electrical currents with a wide frequency range from direct current to alternating currents with frequencies up to several kHz or even MHz.
Innovation Solution
A current sensor structure is designed with a conductor and a current sensor offset from the center in an orthogonal direction, integrated circuits on a printed circuit board, and optionally a ferromagnetic shield to reduce the impact of stray magnetic fields and improve measurement accuracy across varying frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the current sensor is placed at the center of the conductor, then the measurement of magnetic field strength is simplified, but the sensor becomes more susceptible to stray magnetic fields and external interference
Solution Approach 1:
The patent applies asymmetry by deliberately positioning the current sensor at an offset location rather than the center of the conductor. This asymmetric placement creates a specific geometric relationship between the sensor and the conductor that enables the sensor to measure the magnetic field generated by the current while being less susceptible to external magnetic field interference. The offset distance is carefully chosen to optimize the sensor's response characteristics.
2Object-affected harmful factors
If the current sensor is offset from the center, then immunity to external magnetic fields is improved, but the complexity of the sensor structure increases
Solution Approach 1:
The patent utilizes parameter changes by adjusting the offset distance between the sensor and the conductor center, as well as modifying the sensor's sensitivity characteristics. By optimizing these parameters, the sensor achieves enhanced immunity to external magnetic fields while maintaining a relatively simple structure. The specific offset distance and sensor sensitivity are tuned to balance performance requirements with structural simplicity.
3Measurement precision
If the sensor is designed for accurate DC current measurement, then measurement precision is improved, but the ability to measure AC currents across a wide frequency range deteriorates
Solution Approach 1:
The patent implements universality by designing a current sensor with offset positioning and adjusted sensitivity characteristics that enable it to perform accurately across multiple current types and frequency ranges. The sensor's geometric configuration and electrical characteristics are optimized to provide consistent performance from DC through AC measurements, making it a multi-functional device capable of handling diverse measurement requirements without requiring separate specialized sensors.
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 structure enhances stability and consistency in magnetic field measurements for alternating currents, improves immunity to external magnetic fields, and maintains accuracy across a wide frequency range.
Implementation Method 1
One method for detecting and measuring an electrical current in an electrically conductive wire uses a Hall sensor based on the Hall effect. The Hall effect is the production of a voltage difference (the Hall voltage) across an electrically conductive material (such as a wire), transverse to an electric current in the material and to an applied magnetic field perpendicular to the current.
Implementation Method 2
A current sensor structure is designed with a conductor and a current sensor offset from the center in an orthogonal direction, integrated circuits on a printed circuit board, and optionally a ferromagnetic shield to reduce the impact of stray magnetic fields
Data Source
Figure 1A~1C
Figure 1D~1F
Figure 2A~2D
AI summary
The present invention relates to a current-sensor structure (99) comprising a conductor (20) for conducting electrical current in a current direction (24). The conductor has one or more conductor surfaces (22) and an edge. At least one current sensor (30) is disposed on, over, adjacent to or in contact with the conductor and is offset from a centre of the conductor in an offset direction (28) orthogonal to the current direction. The current sensor (30) is aligned with the edge of the conductor or the conductor has a width W and the current sensor is within a distance of W/2.5, W/3, W/4, W/5 or W/6 of the conductor edge. The current-sensor structure can comprise a substrate on which the conductor is disposed.