Rogowski Current Sensor 3D Stacked PCB Interference Rejection
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Solution Overview
Problem
Current PCB Rogowski coils suffer from reduced resistance to interference due to sub-optimal compensation wire arrangements and two-dimensional designs, compromising their performance in smart meter applications.
Innovation Solution
The design employs two boards, with the current sensing coil on one board and the compensation wire on another, allowing them to overlap, and features radial elements on both sides of the coil board connected via vias, enhancing interference rejection and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a compensation wire is provided outside of the coil or in sub-optimal arrangements, then the device complexity is reduced, but the interference rejection capability deteriorates
Solution Approach 1:
The patent transitions from a two-dimensional PCB layout to a three-dimensional stacked configuration. The compensation wire is placed on a separate board that overlaps with the coil board, creating vertical layering. This dimensional change allows the compensation wire to be positioned optimally for interference rejection without complicating the PCB routing, as the wires operate in different spatial planes.
Solution Approach 2:
The compensation wire board is nested within the area defined by the coil, with the compensation wire forming a loop that encircles the conductor and overlaps with the coil structure. This nesting arrangement maximizes the compensation effect while maintaining a compact overall device footprint.
2Measurement precision
If the coil is designed in a single plane on PCB, then the manufacturing is simplified, but the sensitivity and interference rejection are reduced
Solution Approach 1:
The patent creates a three-dimensional coil structure by stacking the coil board with radial elements on one side and the compensation wire board with overlapping elements on another side. This vertical layering increases the effective sensing area and improves sensitivity to currents in the conductor while maintaining manufacturability through standard multi-layer PCB techniques.
3Measurement precision
If radial elements are connected only on one side of the PCB, then the manufacturing is easier, but the sensitivity to currents is reduced
Solution Approach 1:
The patent utilizes the vertical dimension by placing radial elements on both the top and bottom sides of the coil board, connected through vias. This creates a three-dimensional radial pattern that enhances the magnetic field sensing capability while using standard through-hole via technology for manufacturing.
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 configuration significantly improves interference rejection and sensitivity of the current sensor, making it more effective in detecting currents while reducing external interference.
Implementation Method 1
Magnetic transducers work by detecting changes in the magnetic fields generated by the current carrying conductor
Implementation Method 2
The loop, or compensation wire, is for cancelling the effect external fields generated by conductors passing close to the axis of the toroid
Data Source
Figure 1~2
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AI summary
The present disclosure provides an improved Rogowski-type current sensor. In order to allow the sensing coil and the compensation wire to overlap, the sensor is produced using two boards. The current sensing coil is provided on one board, and the compensation wire is provided on another board. The coil and the wire are arranged such that they at least partially overlap, and ideally the compensation wire is formed entirely within the area defined by the coil, albeit in a different plane. This arrangement makes the current sensor far better at rejecting interference than prior art PCB arrangements. In addition, the coil may be formed on a two-sided board. The board has upper radial elements formed on an upper surface, and lower radial elements formed on lower surface. The radial elements are connected using vias formed in the board. The upper radial elements are arranged in a first plane, and the lower radial elements are formed in a second parallel plane. The upper radial elements are arranged so that they are aligned with the lower radial elements, such that a pair of radial elements form a radial plane that is perpendicular to the board surface. This symmetry ensures excellent sensitivity to currents in a conductor.