Planar Current Sensor with Segmented Dipole Coils for Channel Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing current sensors for electricity metering fail to achieve good isolation between multiple sensors placed in close proximity, particularly in polyphase meters with adjacent current terminals, while also requiring immunity to external AC and DC magnetic fields and a wide dynamic range.
Innovation Solution
A current sensor using a novel planar coil structure with three or more dipole coil segments, balanced to eliminate responses to uniform and gradient magnetic fields, and optimized to maximize sensitivity to local currents while rejecting signals from neighboring conductors, achieving high rejection ratios of around 10000:1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple current sensors are placed in close proximity for polyphase metering, then measurement coverage is improved, but isolation between channels deteriorates
Solution Approach 1:
The sensor coil is segmented into multiple discrete windings (first winding, second winding, third winding) arranged in specific spatial configurations. Each winding segment responds to magnetic fields from specific conductor positions, allowing the sensor to distinguish between signals from adjacent conductors through differential processing of the segmented outputs.
Solution Approach 2:
Different winding segments are positioned to have different local sensitivities to magnetic fields from conductors at specific locations. The first winding is optimized for one conductor position while the second and third windings are optimized for adjacent conductor positions, creating local quality variations that enable channel isolation in close proximity.
2Ease of manufacture
If planar coil structures are used for current sensing, then manufacturing simplicity is improved, but immunity to external magnetic fields deteriorates
Solution Approach 1:
The planar coil structure employs asymmetric winding arrangements where the first winding has a different configuration than the second and third windings. This asymmetry creates differential response characteristics that allow the sensor to reject uniform external magnetic fields while maintaining sensitivity to the differential magnetic fields produced by current-carrying conductors.
Solution Approach 2:
The sensor design converts the harmful effect of external magnetic fields into a beneficial feature by using differential measurement. The asymmetric winding configuration ensures that uniform external fields produce equal and opposite signals in different windings, which cancel out during differential processing, while the desired conductor signals are enhanced.
3Length of stationary object
If sensors respond to mid-field region signals, then detection range is improved, but channel interference increases
Solution Approach 1:
The sensor design transitions from considering only the magnitude of magnetic field signals to utilizing the spatial dimension of field origin. By arranging windings in specific three-dimensional configurations relative to multiple conductors, the sensor can distinguish between signals from different spatial locations even when they fall within the mid-field region, effectively adding spatial discrimination capability.
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 enables independent measurement of currents in each phase of a three-phase electricity meter with minimal interference, maintaining immunity to external magnetic fields and achieving high sensitivity ratios, thus addressing the limitations of existing sensors.
Implementation Method 1
current sensors that respond to magnetic field generated by current flowing in a conductor connected to a load... respond to the rate of change of current in the conductor
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention is a current sensor architecture using a planar coils in close proximity to a current conductor to detect the rate of change of current in the conductor (and hence, by using an integrator, to recover the AC current). The current sensor is optimised to reject uniform external magnetic fields, gradient external magnetic fields, and fields from one or more conductor assemblies in fixed locations in close proximity to the current sensor, such as might be found in a polyphase electric meter with multiple current sensors.