Injection Of Current Pulses Research Articles

Temperature Co-Estimation of Stator Winding and IGBT Module of Automotive Electric Drive System Based on Sequential Current Pulse Injection

Temperature Co-Estimation of Stator Winding and IGBT Module of Automotive Electric Drive System Based on Sequential Current Pulse Injection

Impact Analysis of High-Altitude Electromagnetic Pulse Coupling Effects on Power Grid Protection Relays

Protection relays are important equipment used for protection, control, and metering functions in the power grid. These relays are used to protect critical and difficult-to-replace equipment, like generators, transformers, and capacitor banks. Once the protection devices are disturbed or damaged, a high risk of power generation interruption occurs. Therefore, it is important and necessary to study the relay’s immunity to electromagnetic pulse (EMP) events. As a preliminary step toward empirical experimentation on actual equipment, this manuscript outlines an economical and efficient methodology for evaluating the impact of an EMP. An impedance measurement strategy was employed to model the equipment, setting the stage for subsequent immunity analyses. These analyses included the pulse current injection (PCI) method, which utilized an injecting probe to introduce the transient, and frequency domain electromagnetic (FEKO) simulation, which integrated electromagnetic coupling effects into the transient simulation. The impedance measurement and simulation results in this paper provide a reliable basis for gauging equipment performance in the face of HEMP threats. The results obtained using the PCI and FEKO simulations demonstrated the performance of different port responses under a high-altitude EMP, indicating the requirement for some protection to ensure the reliable operation of relays.

Response Characteristics of a ZnO Arrester Under Nanosecond Electromagnetic Pulse

Zinc oxide arresters, a major type of overvoltage protection equipment in power systems, can suppress transient lightning overvoltage, operation overvoltage, and other types of power surges. However, the response characteristics and protection effects under nanosecond pulses, such as those in a high-altitude electromagnetic pulse conduction region, remain unclear. Therefore, the surge protection performance of arresters should be properly understood, and high-performance arresters should be developed. In this study, critical parameters, including overshoot peak voltage, residual voltage, response time, and voltammetry characteristics of a representative 10 kV ZnO arrester under nanosecond pulses, were obtained using a double exponential pulse current injection source. The overshoot peak voltage of this arrester under a nanosecond pulse is 2.19 times of lightning impulse residual voltage, and the residual voltage ratio under a nanosecond pulse is 4.31. The average response time is approximately 45 ns, and the response time is independent of the nanosecond pulse amplitude. Furthermore, an electromagnetic transient model of this type of lightning arrester is established based on the CIGRE guidelines, as well as a method to determine the key parameters. The model can simultaneously account for the response characteristics of the small current region and the conduction region of the arrester, which properly agrees with the experimental results.

Assessing the vulnerability of solar inverters to EMPs: Port testing, PCI modeling, and protection strategies

Renewable energy sources are becoming an ever-larger contributor to the power grid. These renewable energy sources depend upon the power electronic devices, specifically inverters, being essential for connecting Photovoltaic (PV) generation to the grid. However, the Electromagnetic Pulses (EMPs) caused by the high-altitude nuclear explosions can generate fast broad-band pulses with nanosecond rise time, potentially causing damage or destruction to electronic components. To assess the vulnerability of PV inverters to high-altitude EMPs, the port testing and Pulsed Current Injection (PCI) modeling schemes are proposed based on the port impedance analysis. Wide-band frequency measurements are achieved by fusing impedance results from three vector network analyzers. Then, a PCI model is used to simulate the induced response to EMP, with two typical immunity levels of EC5 and EC8 tested. The experiment successfully excites the induced voltage and current under EMP, where the voltage and current can reach 1500V/40A and 8000V/150Aunder EC5 andEC8, respectively. The port vulnerability analysis results demonstrate that only some ports can survive under EC5. To defend against the impact of EMP, three protection strategies are discussed.

HEMP Protection of Power Systems in Electromagnetic Shielding Cabinet

High-altitude Electromagnetic Pulse (HEMP) has a significant impact on power systems. This paper simulates the HEMP coupling for three types of power cables in an electromagnetic shielding cabinet. Besides, this paper proposes the HEMP protection circuit design for 220 V AC and 24 V DC power. In a lightning conduction injection test, the circuit reduces the peak voltage by 12.1 and 14.2 times for AC and DC, respectively. In a pulsed current injection (PCI) test, the circuit reduces the transient peak current to less than 8.2 A for both AC and DC.

NEMP Protection of Antennas in Mobile Communication System: Simulation and Circuit Design

Nuclear Electromagnetic Pulse (NEMP) is highly destructive to mobile communication systems. This paper targets the RF front door of shortwave and ultra-shortwave antennas, simulates the NEMP excitation and coupling effect of two types of antennas (half-loop and whip) based on the CST Microwave Studio platform (CST), and proposes a circuit design for NEMP protection. The protection circuit reduces the transient peak current to less than 5 A in a standard pulsed current injection (PCI) test. The simulation model and the circuit design may be references for the NEMP/HEMP protection of mobile communication systems.

Observation and verification of surface electrical explosion driven by radial‐distributed pulsed current in laboratory lightning strike test

AbstractThe laboratory lightning test is essential for assessing the effectiveness of lightning strike protection (LSP). Particularly, direct lightning strike damage can be performed with pulsed current injection into the specimen. This paper focuses on the dynamic process of arc plasma and shock wave behaviour in the vicinity of the ‘strike’ point. A rod‐plate discharge load is built for testing aluminium and coated plate under 40‐kA‐level pulsed current. The visualisation of the luminous discharge plasma and its flow field via high‐speed photography (from different angles) is meticulously designed and implemented, synchronised with electro‐physical diagnostics. The results indicate some new mechanisms for lightning strike damage, apart from the impulse heat loading from the thermal arc. The transient current injection through the arc root concentrates on a thin skin layer (skin‐depth effect), with the radial‐attenuated current density, driving asynchronously electrical explosions on the plate surface. The inhomogeneous Joule heating of the plate leads to outwardly propagating phase transition and shock wave along the conductive surface. In addition, the electro‐thermal instability is observed and regarded as the seed of irregular erosion region. Spectroscopic information reveals two different plasma states of main discharge arc channel and adjacent surface electrical explosion. The correspondence of the physical mechanism of electrical explosion and optical radiation is established. Microscopic images for different regions depict erosion characteristics and summarise influencing factors, further confirming the mechanism above. The research clarifies the role of skin‐depth effect in transaction arc erosion for electrode, complements the electrical explosion theory with unevenly distributed current and helps optimise strategies of LSP.

Low Cost and Sustainable Test Methods to Study Vulnerabilities of Large-Scale Systems against EMP

Intense electromagnetic pulses are electromagnetic waves with sharp rise time, high field strength and short duration. They have attracted more and more attention in recent years because they can cause destructions or malfunctions of some key national core infrastructures, such as power grids, communication and financial networks, etc. Hence, it is important to harden these facilities to ensure that they can survive in the face of electromagnetic pulse attacks. A direct way to investigate the vulnerabilities of these facilities is placing them in the electromagnetic environments generated by EMP simulators. However, the scale of facilities under test are limited by the working volumes of simulators. With the increase in working volumes and field strength, the price and technical difficulty of simulators are increased. Therefore, low cost and sustainable test methods to investigate vulnerabilities of large-scale systems against EMP are proposed in this study. The study takes advantage of continuous wave immersion (CWI) test and pulse current injection (PCI) test methods, which are low cost and sustainable to predict the pulse responses and assess the nonlinear effect of large-scale facilities under EMP attacks. In a CWI test, the magnitude of the transfer function of large-scale systems or facilities can be measured, and the corresponding phase information of the transfer function can be reconstructed by minimum phase algorithm (MPA) if the systems meet the minimum phase condition. After acquiring the entire information of the transfer function, we can predict the responses of a system under threat-level EMP attacks. However, these responses are obtained under the assumption that the system does not have nonlinear effects. Because the CWI is a low-level test, it cannot simulate the threat-level EMP attacks. In the PCI test proposed here, a bulky pulse current is coupled into the system to stimulate enough current intensity, just as the system was attacked by threat-level EMPs. In this situation, the system would be destroyed, or any other nonlinear effect would occur in the system. After that, the problem is to determine the quantities of the injected current, and a few kinds of norms are introduced in this paper to define the quantities. The method proposed here innovatively takes the experimental results of CWI as reference inputs of PCI tests. In this paper, the accuracy of the response prediction is validated by means of simulations and experiments. Results show that as a low-level test method in the frequency domain, the CWI test method can not only analyze couplings of external electromagnetic energy from frequency domain but also predict responses of the facilities under high amplitude electromagnetic pulses. The nonlinear effect of large-scale facilities can be assessed by applying the PCI test method with the results from CWI prediction. Therefore, if infrastructures or facilities are too large to be tested under EMP simulators, an alternative approach is to carry out the CWI and PCI experiments.

Response of a Surge Arrester With a Series Gap for 6.6-kV Distribution Lines to Steep-Front Transients

Surge arresters with a series gap are commonly installed in distribution lines to effectively protect insulators, transformers, and other equipment from lightning threats in Japan. On the other hand, it has been well known that the high-altitude electromagnetic pulse (HEMP) at an early stage, called E1 HEMP, may extensively cause overvoltage on distribution lines, and the rise time of the E1 HEMP is as short as a few nanoseconds, which is much shorter than that of lightning electromagnetic pulses. To evaluate the effectiveness of surge arresters with a series gap against overvoltage induced by the E1 HEMP, it is necessary to evaluate the effect of a discharge delay due to the series gap on the protection level of surge arresters for steep-front transients. In this work, using a pulse current injection system, we apply a high voltage to a surge arrester with a series gap widely used for 6.6-kV distribution lines in Japan and measure the response of the surge arrester to steep-front transients. From the measured results, we obtain the voltage–time characteristics of the surge arrester with a series gap and residual voltages, which are compared with the results for lightning impulse voltage.

Port Impedance Measurement and Current Injection Response Analysis for PLCs

Programmable logic controllers (PLCs) are used to control devices throughout the power system since they have fast control capabilities and can utilize multiple types of communication interfaces. Therefore, studying and mitigating their vulnerabilities to electromagnetic pulse is important for the reliability of PLC operations. In this article, an effective impedance measurement scheme is proposed and demonstrated for three PLCs to estimate their susceptibility to an electromagnetic pulse. The equivalent nonuniform transmission line model is established to eliminate the impact of the fixture in the de-embedding process. Then, different parameters of the impedance measurement setup are explored. Based on the measured impedance, the equivalent circuit is established to calculate the response of the device when subjected to the electromagnetic pulse. The voltage and current responses of different interfaces are compared utilizing the developed pulsed current injection (CI) method. Finally, the impedance measurement scheme is verified through testing using three measuring instruments. And the CI simulation experiments reveal the characteristics and susceptibilities of different PLCs interfaces, indicating that some protection measures are required for the reliable operation of the PLC.

Dapagliflozin exhibits class I antiarrhythmic effects which suppress action potential formation in human atrial cardiomyocytes

Abstract Background Recently, inhibitors of sodium-glucose transporter 2 (SGLT2i) were shown to have tremendous cardioprotective effects in patients with type 2 diabetes mellitus (T2DM) as well as heart failure (HF) patients, regardless of their glycemic status. Among other beneficial effects on cardiovascular outcome an antiarrhythmic effect of SGLT2i was indicated. In patients with T2DM therapy with SGLT2i was associated with a significantly reduced risk of atrial arrhythmias and sudden cardiac death. As sodium-glucose transporter 2 (SGLT2) is not expressed within the heart underlying molecular modes of action remain unclear. Therefore, investigating possible antiarrhythmic mechanisms is crucial to determine whether SGLT2i might be beneficial for all patients suffering from arrhythmias, regardless of other comorbidities. Purpose To assess antiarrhythmic effects of SGLT2i on a molecular and cellular level. Therefore, direct electrophysiological effects of dapagliflozin – the most advanced SGLT2i in clinical trials – on action potential (AP) formation in atrial cardiomyocytes (CM) was investigated. Methods Effects of dapagliflozin on human NaV1.5, heterologously expressed in Chinese hamster ovary (CHO) cells, was investigated using the patch-clamp method. Further, effects on voltage-gated sodium channels (NaV) were also measured in human atrial CM. Consequences of dapagliflozin treatment on AP formation were studied on isolated human and porcine atrial CM using the patch-clamp technique. APs were elicited in current-clamp mode by injection of brief current pulses. Results Dapagliflozin (100 μM) significantly decreased peak sodium currents in human atrial CM as well as CHO cells, expressing human NaV1.5 channel subunits. Additionally, half-activation potential of voltage-gated sodium channels was significantly increased after administration of dapagliflozin. Furthermore, dapagliflozin (100 μM) suppressed AP formation in CM isolated from human and porcine left and right atrial tissue. In human CM action potential amplitude (APA) was significantly reduced by 34.3%, while APA inhibition by dapagliflozin averaged out at 30.7% for porcine CM. In porcine CM action potential duration at 50% (APD50) and 90% repolarization (APD90) were also significantly reduced. Conclusion Dapagliflozin suppresses AP formation in human and porcine atrial CM by inhibiting voltage-gated sodium currents. Therefore, we suppose that dapagliflozin exhibits class I antiarrhythmic effects. Funding Acknowledgement Type of funding sources: None.

Synopsis of the September 2022 Issue of the IEEE Letters on Electromagnetic Compatibility Practice and Applications

In this letter, experimental characterization and behavioral modeling of an off-the-shelf damped sinusoidal wave generator operating at different frequencies are addressed. Two modeling strategies are developed which lead to an active and a passive circuit representation of the generator, whose involved parameters are optimized by making use of time-domain measurement results obtained with the generator connected to different load impedances. It is shown that either the active or the passive model can assure accurate prediction of the generated waveforms, depending on the specific frequency. The proposed models can be effortlessly implemented in common circuit simulators, and used for systematic design of injection devices for transient conducted susceptibility testing as well as for simulation of the corresponding test setups. As an illustrative example, the proposed models are exploited to predict the actual waveform induced at the input pins of the device under test in a simplified pulse current injection test setup.

Behavioral Modeling of an Off-the-Shelf Damped Sinusoidal Transient Generator

In this letter, experimental characterization and behavioral modeling of an off-the-shelf damped sinusoidal wave generator operating at different frequencies are addressed. Two modeling strategies are developed which lead to an active and a passive circuit representation of the generator, whose involved parameters are optimized by making use of time-domain measurement results obtained with the generator connected to different load impedances. It is shown that either the active or the passive model can assure accurate prediction of the generated waveforms, depending on the specific frequency. The proposed models can be effortlessly implemented in common circuit simulators, and used for systematic design of injection devices for transient conducted susceptibility testing as well as for simulation of the corresponding test setups. As an illustrative example, the proposed models are exploited to predict the actual waveform induced at the input pins of the device under test in a simplified pulse current injection test setup.

Experimental Study on the Coupling Mechanism of Sensors under a Strong Electromagnetic Pulse.

This paper presents a study on the electromagnetic effects of a main fuel control system under the action of a strong electromagnetic pulse. It assesses the electromagnetic sensitivity of a speed sensor and a linear variable differential transformer (LVDT) sensor. This assessment focuses on the control system’s electromagnetic effects and the sensors’ coupling signals. The effects and signals were determined using radiation and pulse current injection tests. Analysis of the signal at the system power port shows that it is the same as those for the two test methods. Based on analysis of the working mechanism and terminal signals of the sensors, the electromagnetic sensitivity of the system is different under the different electromagnetic pulse conditions. The electromagnetic sensitivity characteristics of the sensors were verified, and the electromagnetic effects of the main fuel regulation control system were analyzed. Meanwhile, the degree of sensor coupling mechanism caused by the electromagnetic coupling effects of the main fuel regulation control system under strong electromagnetic pulses were studied. These findings have clear practical implications for electromagnetic pulse protection of aero-engine control systems.

Ultra-compact VCSEL scanner for high power solid-state beam steering.

We demonstrate the lateral monolithic integration of a tunable first-order surface-grating loaded vertical-cavity surface-emitting laser (VCSEL) and slow-light waveguide with fan-beam steering and amplifier function. Shallow Bragg-grating formed on the surface of a VCSEL section enables the selection of a single slow-light mode, which can be coupled into the integrated long waveguide and amplified through pumping the amplifier above threshold. We obtained over 3W amplified slow-light power with single-mode operation and over 4W amplified quasi-single-mode power under pulsed current injection. To the best of our knowledge, this is the highest output power for single-mode VCSELs. Solid-state beam steering of the device is also demonstrated with 9° fan-beam steering range and 200 resolution points.

Spectral Characteristics of Terahertz Quantum Cascade Lasers

Terahertz quantum cascade lasers (THz QCLs) are prospective radiation sources for high-resolution gas spectroscopy. A wide range of operating frequencies (from 1.2 to 5.4 THz), a narrow generation line (up to 10 kHz), the ability to operate on several radiative transitions (two-color lasers, generation of frequency combs) and other unique characteristics of THz QCLs make it possible to create a new generation of gas spectrometers for biomedical and environmental applications. The article discusses the possibilities of controlling the spectral characteristics of THz QCLs by changing the operating temperature and parameters of the injection current pulses: amplitude, duration, and repetition rate. For the first time, the study of energy transfer between longitudinal Fabry — Perot modes in THz QCLs with a change in the duty cycle of injection current pulses has been carried out.

Research on Electromagnetic Susceptibility of Electronic Modules in Component-Level HEMP PCI Test

The study of electromagnetic sensitivity of electronic modules is crucial for the selection of a component-level pulse current injection (PCI) waveform, which will determine whether a component-level PCI test is equivalent to a system-level pulse illumination test of the system to which the electronic module belongs. For electromagnetic sensitivity analysis, the equivalence between the injection waveform and a typical high-altitude electromagnetic pulse (HEMP) conducted disturbance waveform in a component-level PCI test is studied. Based on an RF low noise amplifier (LNA) test board, component-level PCI tests were performed using 20 ns/500 ns double exponential wave and square-wave pulse with multiple pulse-widths. The damage threshold was analyzed and determined by using vector norm and its internal damage was observed and validated by optical microscopic analysis. The conclusions are demonstrated as follows: first, during square-wave PCI tests of RF LNA, the electromagnetic sensitive parameter action is divided into three regions by pulse-width range, called ∞-norm, 2-norm and competitive failure-dominating regions; second, the electromagnetic damage effect of the RF LNA is mainly caused by the burning of its two cascaded transistors, forming a pulse energy transmission channel with short-circuit impedance from the input port to the ground; third, the 100 ns-width square waveform can be determined as the equivalent injection waveform of a HEMP conducted waveform, and the pulse peak value of injected current is determined as the electromagnetic sensitive parameter for square-wave PCI tests of the RF LNA. The conclusions verified the feasibility of establishing the equivalence between different pulse waveforms according to the electromagnetic sensitivity analysis based on the vector norm theory and effect mechanism analysis.

Performance Evaluation of Inductive and Capacitive Couplers for Pulsed Current Injection

Pulsed current injection (PCI), as an important conducted susceptibility testing method, has been introduced in several standards. However, the selection of couplers for PCI tests has not been clearly specified, which leads to the fact that the injected electrical quantities by different couplers might be rather different and it is inadequate to inject the proper disturbance at the testing ports. So, it is of significance to evaluate their performance quantitatively and determine the usage scenarios for couplers. This article focuses on the quantitative performance evaluation of inductive and capacitive couplers including inductive ferrite-core clamps and capacitive coupling clamps. A distributed-parameter multiconductor transmission line (MTL) model has been proposed for couplers clamped on <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> wires. The validation test confirms the accuracy of the model in the bandwidth of PCI tests. The performances of an inductive coupler and a capacitive coupler are analyzed and compared based on MTL models. The selection criterion of the couplers is concluded as that a proper coupler should lead to higher time-waveform norms, which indicate possible nonlinear effects of the tested objects, such as the overcurrent, the turn-to-turn breakdown, and the component burnout.

Broadband and tunable optical frequency comb based on 1550 nm verticalcavity surface-emitting laser under pulsed current modulation and optical injection

Optical frequency combs (OFCs) each consist of a set of equally spaced discrete frequency components, and they have been widely applied to many fields such as metrology, optical arbitrary waveform generation, spectroscopy, optical communication, and THz generation. In this work, we propose a scheme for generating broadband and tunable OFCs based on a 1550 nm vertical-cavity surface-emitting laser (VCSEL) under pulsed current modulation and optical injection. Firstly, a pulsed electrical signal is utilized to drive a 1550 nm-VCSEL into the gain-switching state with a broad noisy spectrum. Next, a continuous optical wave is further introduced for generating broadband and tunable OFC. Under injection light with power of 18.82 µW and wavelength of 1551.8570 nm, and pulsed electrical signal with a frequency of 0.5 GHz and pulse width of 200 ps, an OFC with a bandwidth of 82.5 GHz and CNR of 35 dB is experimentally acquired, and the single sideband phase noise at the 0.5 GHz reaches –123.3 dBc/Hz at 10 kHz. Moreover, the influences of injection light wavelength, frequency and width of pulse electrical signal on the performance of generated OFC are investigated. The experimental results show that OFCs with different comb spacings can be obtained by varying the frequency of pulsed electrical signal. For the frequency of pulsed current signal varying in a range of 0.25 GHz–3 GHz, the bandwidth of generated OFCs can exceed 60 GHz through selecting optimized injection optical wavelength and width of pulse electrical signal.

All-solid-state pulsed current injection source based on the light initiated multi-gate semiconductor switches.

To study the damage and protection mechanism of the transient electromagnetic pulse to the cables of the electronic equipment under test, an all-solid-state pulsed current injection source with light initiated multi-gate semiconductor switches is developed. The output peak current range of the prepared all-solid-state pulsed current injection source was 0.1-1kA, the risetime was 18ns, and the pulse width was 520ns. In addition, the waveforms of the output peak current were consistent.