Current probes have long been used for Electromagnetic Compatibility (EMC) pre-compliance and diagnostic purposes. Dipole and transmission line-based models are often used to relate Common-Mode (CM) current levels to potential Radiated Emission (RE) levels. This relationship enables RE estimates to be performed without the use of accepted certification methodologies – reducing project costs and timelines. These models are based on a set of assumptions which cannot fully match real-world scenarios. This article expands the discussion by examining the relationship between the CM current and RE of a representative metallic structure using both measurements and a Finite Element Method (FEM) code. The relationship is shown to be frequency dependent, resulting in both over and under prediction of the RE levels. A practical recommendation is made on how to exploit the equivalence of CM current-based estimations of system RE.

In many contexts, particularly in Electromagnetic Compatibility (EMC), a common-mode Current Probe (CP) is intended to be a non-invasive transducer. We introduce its applications generally, but focus on transient waveform measurements. The complex form of our 10 Hz to 1 GHz CP Transfer Impedance (Zt) is measured using Vector Network Analysers. Measured data are compared to manufacturer calibration data and a choice made on the best form of the complex Zt for transient analysis. We then inject a time waveform into a test system and use the Zt to reconstruct the signal, using the inverse Fast Fourier Transform algorithm. The reconstructed current waveform is compared to a reference observation for validation. For frequencies between DC and 240 MHz, a good correlation can be achieved. We raise relevant discussions on filtering, calibration system resonance and de-embedding.  

Lightning-produced electromagnetic fields can couple into photovoltaic (PV) installations and cause damage. This study examines the far-field radiation patterns of a small and a large PV module between 9 kHz and 30 MHz â\euro“ by both measurement and simulation. Due to reciprocity, these are also the susceptibility patterns. Firstly, the radiation patterns of each PV module are measured using a vector network analyser and a receiving loop antenna at multiple positions. Secondly, the radiation patterns of each PV module are computed using a novel circuit-computational electromagnetic hybrid methodology. This methodology is applied to two literature-based models, as well as four recently-proposed PV module models. Postprocessing is applied to both the measured and simulated results to produce the realized gain in each case - allowing fair comparisons to be made. The measured gain results over the full frequency range are then presented. The small PV module shows low levels of gain, peaking at -32.5 dB at 30 MHz, whilst the large PV module shows much higher levels of gain, peaking at -16.9 dB at 10.5 MHz. Following this, the measured and simulated radiation patterns are compared at the frequencies where maximum gain occurs. The small PV module exhibits directional radiation characteristics, whereas the large PV module shows omnidirectional operation â\euro“ one of many novel findings produced by this study.

This study presents a simulated analysis of the response of a photovoltaic (PV) module to a single indirect lightning stroke. It does so by separately passing positive and negative 20 kA, 8/20 µs lightning current waveforms through a wire in space, located 1 m from the centre of a vertically-orientated PV module, and monitoring the voltages and currents at the PV module output terminals. Typically, literature uses an unvalidated, wire-based equivalent model for this purpose. Recent research has demonstrated the substantial shortcomings of such a wire-based equivalent model when viewed from the following three perspectives: differential mode impedance, internal coupling, and differential mode radiation. What sets this study apart is that it consolidates the novel advances made in multiple recent PV-orientated studies, all of which are centred around the high-frequency modelling of PV modules. These advances include improved three-dimensional structures which are coupled to nonlinear circuits using a hybrid simulation approach. These measurement-validated novel hybrid models have been shown to produce results which are substantially more accurate than the wire-based equivalent models when examined from the three aforementioned perspectives. This study progressively implements these models, demonstrating the absolute necessity of properly incorporating each aspect. Wire-based equivalent models are shown to produce overestimated levels of induced voltage and current. Furthermore, the use of linearised circuits to represent the inherently nonlinear operation of PV cells - a practice prevalent in such research - is demonstrated to be an oversimplified approach. Finally, the importance of considering the behaviour of the often-omitted, and therefore overlooked, bypass diodes is emphasised.Â

Large photovoltaic (PV) modules comprise multiple series-connected internal strings, which are in turn composed of series-connected PV cells. When excited with time-varying signals, the loops formed by these internal strings couple to each other. Until now, this coupling has not been considered in any radio frequency interference studies of PV systems. This article examines this coupling both practically and computationally as follows. Firstly, the loop-to-loop coupling within a large (310 W) PV module is quantified through a careful series of low-frequency vector network analyser measurements – the first novel contribution of the study. Secondly, a recently-proposed circuit-computational electromagnetic hybrid methodology is applied to this coupling problem, investigating it computationally â\euro“ the second novel contribution of the study. The four newly-formulated PV models which utilise this hybrid methodology are assessed, as well as two literature-based models. Thirdly, a comparison of the measured and simulated results is performed â\euro“ the third novel contribution of the study. This crucial validation step is performed by examining the scattering parameter results, both visually and by means of the acclaimed Feature Selective Validation (FSV) method. The literature-based models exhibit poor FSV correlation in all cases, while the improved models show good-to-excellent FSV accuracy - a vast improvement.

A novel circuit-computational electromagnetic (CEM) hybrid simulation methodology, which results in vast improvements in the accuracy of high-frequency photovoltaic (PV) modelling between 1 Hz and 50 MHz, is proposed. At low frequencies, the impedance of a PV module is dominated by the behaviour of the PV cells, while at high frequencies it is dominated by the layout of the inter-cell connections. The proposed methodology considers both the low and high-frequency behaviour of a PV module in a single simulation. Firstly, the impedances of two PV modules are carefully measured using two vector network analyser configurations. Secondly, literature-based models of PV modules are adapted to the proposed methodology. Thirdly, improved models of each PV module are introduced in four ascending levels of complexity. These improved models comprise additional novel aspects, including distributed cell layouts and implicit CEM-calculated self-inductances. Fourthly, a feature-selective method is used to compare the measured results with the literature-based and improved models. This analysis yielded comparable error reductions of up to a factor of 400 – highlighting the value of the improved methodology and models. Penultimately, the required level of computational resources is introduced, and the trade-off between simulation time and accuracy is discussed. Finally, a review discussion is presented.