Rogowski Coil Current Transducer Research Articles

A miniaturized Rogowski current transducer with wide bandwidth and fast response

The miniaturization of the 3D Rogowski current transducer down to the micro-scale is essential for device integration and expansion of its application scope, particularly for ‘lab-on-a-chip’ systems. However, fabrication of 3D miniaturized Rogowski coils remains challenging as most relative methods still rely on the 2D micromachining process. In this paper, a miniaturized Rogowski coil current transducer was fabricated using an improved femtosecond laser wet etching technology and a metal microsolidification process, in which a metal alloy with a relatively high melting point was used and a robust but simple packaging structure based on a conical electrode was developed. The results show that the miniaturized Rogowski coil current transducer reveals a response time of less than 1 ns, high sensitivity and good detection capability for high-frequency electrical signals. The miniaturized Rogowski coil can easily be integrated into functional microsystems and will be widely applicable for high-frequency electric signal detection and circuit protection.

Continuous calibration of Rogowski coil current transducer

Rogowski coils (RC) intended for high-accuracy contactless current measurement ask for precise sensor geometry and specific conditions, such as a centered primary conductor. To release these constraints, we propose in this paper a recently patented continuous calibration system which features a reference conductor added coaxially to the primary conductor and a proportional-integral controller integrated in CMOS technology. The chip is mounted on a board with a precise shunt and a AC reference signal generator. The magnitude of this reference signal may exhibit slow variations, only its frequency needs to be accurate, which is a great advantage. The architecture of the chip is described as well as the experimental setup. Experimental results obtained with commercial flexible RC show that the sensor immunity to the conductor position, as well as the dispersion between several RC, is reduced to ?0.1 %, i.e. a 0.1 class measurement. In addition, the system may ensure an absolute calibration of the RC current transducer, avoiding any costly calibration procedure at the end of the sensor manufacturing.

Rogowski coil current transducer compensation method for harmonic active power error

In the harmonic active power measurement, the highest uncertainties are generally introduced by the current and voltage transducers. In a previous paper, the authors showed that the current transformer (CT) can introduce significant errors in such measurement, especially if the phase shift between voltage and current is close to ±90°. In such condition the errors on harmonic power measurement are mainly due to the CT phase displacement. This paper shows that better results can be achieved with more linear transducers, such as the Rogowski coil current transducers (RCCTs), whose metrological performance in distorted condition can be improved, by means of a proper compensation method. The proposed method for RCCTs compensation is based on the frequency response and it allows to reduce the errors on harmonic power measurement, also for phase shift close to ±90°. The study is supported by several experimental tests.

Characterization and Error Compensation of a Rogowski Coil in the Presence of Harmonics

This paper reports the results of an experimental study dealing with a commercial Rogowski coil current transducer (RCCT) in the presence of harmonic distortion. The RCCT was observed under two conditions: 1) sinusoidal excitation with frequencies from 50 to 750 Hz and 2) nonsinusoidal excitation using fundamental frequency and one harmonic, with adjustable amplitude and phase shift. The experimental results show only a weak dependence of the harmonic current ratio error and phase displacement on the amplitude and phase shift of the excitation harmonic. The phase displacement is also independent of the conductor position within the Rogowski coil window. An error compensation method, based on the frequency response, was implemented and tested with a distorted waveform. The compensation method allows one to obtain an improvement of the RCCT accuracy class from 1% and 1 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex></formula> , in the case of a sinusoidal signal at mains frequency, to 0.05% and 0.05 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex></formula> , both for the fundamental and the distorted signal harmonics.

Study of Rogowski Coils for Measuring Pulse Currents of the High-Power Laser Source

Being an indispensable part of the high-power, high-voltage laser source, the PSM (power supply module) must be of high stability and reliability. For achieving such performance, it is necessary to measure the pulse currents of the PSM quickly with high accuracy. A novel instrumentation based on Rogowski coil current transducer (CT) is applied to measure the laser power source. For effectively inhibiting the integrating drift, a new type of integrator is applied in the instrument. The analyses of models, time-domain specifications, and frequency characteristics of the CT are presented. The optimal parameters of the CT, such as damping resistance, parameters of the integrator, and dimension of the coil, are also presented. Both the method to calibrate the degree of linearity of the CT and experimental results for measuring the PSM are presented.