Introduction to Electromagnetic Compatibility

The Rogowski coil is an old device for current measurement. It has been modified and improved over a century and is still being studied for new applications. The Rogowski coil has various advantages over conventional magnetic current transformers (CTs). Not only can it be used instead of CT, but also it has various utilizations in other fields. This paper provides a brief review on different aspects of the Rogowski coil and its advancement procedure, during last decades. In this paper, the history of the coil is brifely reviewed and its bases and applications are discussed. The Rogowski coil is analyzed from different points of view, including different integration techniques in the output stage, models for the Rogowski coil, experimental methods for parameter measurement in models, and method for determining the damping resistor. Finally, a brief review over different applications of the coil ends this paper.

The Rogowski Coil Principles and Applications: A Review

Silicon-carbide (SiC) transistors with growing readiness for the power converter market have raised an emerging need for high-performance gate driver (GD) units to maximize their remarkable characteristics. In particular, the GD units for the SiC devices that experience extremely fast commutations at the medium-voltage level require powerful driving capability, effective short-circuit (SC) protection, and superb common-mode transient immunity. Thereby, this article presents a systematic enhanced GD (eGD) solution that incorporates three scalable features compatible with almost all the SiC mosfet modules. First, a BJT-based multicell current booster is proposed to attain balanced high driving current, low losses, gate-loop inductance less than 1 nH, and great cross-talk immunity. Second, a nonintrusive Rogowski switch-current sensor with high bandwidth and fair accuracy is developed, capable of detecting SC fault in 86 ns and softly turning off 5 kA SC current in 1  $\mu$ s. Third, two noise-free isolation architectures are proposed to mitigate common-mode noise-admittance by more than 100 dB. Fundamentals, analytical designs, experimental validations, and scalability discussions of the three techniques are elaborated, respectively. Finally, a 6-kV, 84-A, and 102-V/ns continuous pump-back test is demonstrated, for the first time, to verify the eGD's excellent performance.

High-Scalability Enhanced Gate Drivers for SiC MOSFET Modules With Transient Immunity Beyond 100 V/ns

Latest wide-bandgap power devices are switching progressively faster compared with existing silicon devices. Their accurate current measurements for either control or protection have therefore become tougher. One method that can fulfill the requirements is to use a Rogowski coil and its accompanied electronics to form a Rogowski current sensor with high bandwidth, small volume, low cost, and ease of integration. This article therefore aims to review various aspects of the Rogowski current sensor from its history, measuring principles to modern power-electronic applications. The applications have, in turn, motivated a progression from traditional helical to recent miniaturized printed circuit board implementation, in order to improve the overall power density. This progression has similarly been reviewed, together with its various design aspects applied to the winding, integrator, shielding, and parameters of the Rogowski current sensor. Future challenges and directions are then summarized, whose ultimate goal is to maximize accuracy over a wide bandwidth without being affected by radiated and near-field-coupling interferences.

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A Review of Traditional Helical to Recent Miniaturized Printed Circuit Board Rogowski Coils for Power-Electronic Applications

With the boom of communication systems on independent platforms (such as, airplanes and vessels), co-site interference has become prominent. Currently, extensive research has been conducted on the ...

Broadband cancellation method in an adaptive co-site interference cancellation system

Rogowski coil is used as a current transducer in complex electromagnetic environment, whose anti-interference property bears on the accuracy of the current measurement. Based on the ordinal straight-coupled foils of the current PCB Rogowski coil, this paper proposes a newly designed PCB Rogowski coil with symmetrical double-printed imprints and returning turn to gain better precision and performance. The mutual inductance between the coil and the primary conductor is chosen as the sensitivity parameter to contrastively analyze the anti-interference property of three coils, including the ordinary straight-coupled coil, the symmetrically printed coil with or without returning turn. The calculation and measurement of mutual inductance have been made under different disturbed conditions, such as the eccentricity from axis of the primary conductor and the influence of external parallel and perpendicular currents. The results indicate that the newly designed PCB Rogowski coil with symmetric imprints and returning turn is good in compatibility, strong in anti-interference property, and also accurate and steady in mutual inductance. Therefore, it is suitably applied as the sensing head of current measurement in the complex stray electromagnetic fields.

Design of PCB Rogowski Coil and Analysis of Anti-interference Property

The invention discloses a short-time slowly-varying high-current measuring device based on a (printed circuit board) PCB type Rogowski coil, and the short-time slowly-varying high-current measuring device comprises the PCB type Rogowski coil, a sampling resistor and signal receiving equipment, wherein an inertialess link integrating circuit and a variable interval (VI) switching circuit are additionally and successively arranged between the PCB type Rogowski coil and the sampling resistor; and the PCB type Rogowski coil is a PCB type Rogowski coil which is provided with symmetrically arranged wires on two faces and is provided with return wires The short time slowly-varying high-current measuring device has the advantages that direct currents or low frequency high currents can be detected, the measuring bandwidth of the short time slowly-varying high-current measuring device can reach up to DC swung dash 200kHz, and the deficiencies of a conventional current sensor on the aspect of measurement of the direct currents or the low frequency high currents are eliminated; and since the PCB type Rogowski coil which is provided with the symmetrically arranged wires and is provided with the return wires is adopted by the short time slowly-varying high-current measuring device as a sensing head, complex electromagnetic interferences in a high-current system can be effectively eliminated, and a full-analog signal transmission manner is adopted by the device, so measurement errors can be effectively reduced

Short-time slowly-varying high-current measuring device based on (printed circuit board) PCB type Rogowski coil

The invention discloses a double-face symmetric wired printed circuit board (PCB) type Rogowski coil. The Rogowski coil comprises a PCB board, wherein the PCB board is provided with N internal diameter guide holes and N external diameter guide holes; the N internal diameter guide holes are uniformly distributed along the circumference of radius r; the N external diameter guide holes are uniformlydistributed along the circumference of radius R; the circumference of the radius r is concentric with the circumference of the radius R; wired copper foils penetrate through the N internal diameter guide holes and/or the N external diameter guide holes in turn and are symmetrically arranged on the two faces of the PCB board along the radius direction; a loop line ring is wound on a wired copper foil on one face of the PCB board; and the radius Rh of the loop line ring is greater than the radius R. The double-face symmetric wired PCB type Rogowski coil provided by the invention has the advantages of high parameter consistency, reproducibility and anti-interference capacity, guarantees a stable mutual inductance coefficient, can conveniently improve the accuracy, can be used as a current sensing head for current measurement under a complex electromagnetic environment, and is easy to produce in batches.

Double-face symmetric wired printed circuit board (PCB) type Rogowski coil

Two new numerical methods are developed in this paper, including computing magnetic inductive intensity via the derivative of geometrical mean distance, and calculating the magnetic energy via the integral on the perimeter, to determine the internal inductance of conductors of rectangular cross section. It is shown that their performances are superior to that of the sophisticated one, which works out internal inductance via the vector magnetic potential. And numerical results also indicate the equality between high-frequency resistance and internal inductive reactance in terms of their ratio which approaches to one at high frequencies.

New numerical methods of computing internal inductance of conductors of rectangular cross section

This paper investigates the influence of the different gains of weight branches to the dynamic characteristic and interference cancellation ratio (ICR) of an analog adaptive interference cancellation system (AAICS). We solved the transient-state and steady-state characteristics of weights. And the rule of ICR varying with the different gains was studied. The difference of the gains of weight control branches leads the convergence speeds of the two weights are different. The convergence speed of the system is decided by the slower weight. Enlarging the gains will improve the average convergence speed and ICR. The analyses are in agreement with the computer simulation. For the different gains, the system is a time-variant system. The more the difference of gains is, the severer THD (Total harmonic distortion) will be. And the new interference will appear.

Anqi Hu

Papers

Design of PCB Rogowski Coil and Analysis of Anti-interference Property

Short-time slowly-varying high-current measuring device based on (printed circuit board) PCB type Rogowski coil

Double-face symmetric wired printed circuit board (PCB) type Rogowski coil

New numerical methods of computing internal inductance of conductors of rectangular cross section

Influence of different gains to adaptive interference cancellation system