Magnetic Field Current Sensor Frequency Compensation
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Solution Overview
Problem
Conventional current sensors face measurement errors due to frequency-dependent skin and proximity effects, limiting their accuracy over a large frequency range, especially when measuring high currents, and require complex geometries or signal processing for compensation.
Innovation Solution
Incorporating conductive compensation elements adjacent to the current conductor to generate a compensation magnetic field that counteracts frequency-dependent distortions, maintaining a constant magnetic field gradient and simplifying the sensor design and electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional current sensors are used for measuring alternating currents, then the measurement is simple and cost-effective, but measurement errors occur due to frequency-dependent skin and proximity effects limiting accuracy over a large frequency range
Solution Approach 1:
The current sensor is segmented into multiple sensor elements arranged in a specific geometric pattern around the conductor. Each sensor element measures the magnetic field at a different position, and the individual measurements are combined through signal processing to calculate the total current. This segmentation allows the sensor to compensate for frequency-dependent effects by comparing field measurements at multiple locations, thereby maintaining measurement accuracy across a wide frequency range from DC to 150 kHz and beyond.
Solution Approach 2:
The patent introduces additional conductive elements as intermediaries between the current conductor and the sensor elements. These intermediary conductors are positioned at specific distances and orientations to generate compensating magnetic fields that counteract the skin and proximity effects. By using these intermediary elements, the sensor system can maintain a linear relationship between the measured signal and the actual current over a broad frequency range without requiring complex signal processing or calibration.
2Measurement precision
If complex geometries or signal processing are used for compensation, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The sensor employs sensor elements with different local characteristics - specifically, elements positioned at varying distances and angles relative to the current conductor. Each sensor element has a tailored geometric configuration optimized for its specific position, creating local quality variations that collectively enable frequency compensation. This approach achieves accurate measurement across a wide frequency range while maintaining a relatively simple overall device structure, avoiding the need for complex signal processing circuits or adjustable components.
3Reliability
If magnetic field-based sensors are used for galvanically isolated measurement, then safety and electrical isolation are improved, but measurement errors due to frequency-dependent effects worsen
Solution Approach 1:
The patent creates a simplified magnetic field model by using multiple sensor elements that collectively capture the magnetic field distribution around the conductor. Instead of directly measuring the complex frequency-dependent field at a single point, the system creates a copied representation of the field through multiple measurements at different positions. This copied field information is then processed to extract the total current, maintaining galvanic isolation while compensating for frequency-dependent effects and improving measurement accuracy.
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 expands the usable frequency range, reduces measurement errors, and simplifies the sensor design and electronics, enabling accurate measurement of high currents from DC to 50-150 kHz with a simple structure and cost-effective implementation.
Implementation Method 1
an alternating current sensor (100) for frequency-compensated measurement of alternating currents, in particular for compensating skin effect and proximity effect in the alternating current (I), based on a magnetic field, with frequency-dependent distortions of an alternating magnetic field being compensatable by a compensation magnetic field generated by induction in at least one conductive compensation element (80)
Implementation Method 2
a current which produces an alternating magnetic field capable of inducing eddy currents in metallic conductors
Implementation Method 3
magnetic field-sensitive sensor element, the sensor element being arranged spatially adjacent to the current conductor for detecting a magnetic field caused by the alternating current
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5b
AI summary
The present invention relates to a current sensor (10, 20, 30, 40, 50, 60, 70) for magnetic field-based determination of an alternating current I by a conductor (38, 56) based on a sensor element (12, 108) which is sensitive to magnetic fields. The sensor element (12, 108) is arranged spatially adjacent to the conductor (38, 56) for detecting a magnetic field caused by the alternating current I in the conductor (38, 56). According to the invention, at least one conductive compensating element (80, 90) is arranged disconnected from the current flow I by the conductor (38, 56) and spatially adjacent to the sensor element (12, 108) and to the conductor (38, 56) for compensating for frequency-dependent distortions of the magnetic field by means of a compensation magnetic field which can be generated by induction.