Search

Research teams from industry and academia have highlighted the advantages obtained from the introduction of Silicon Carbide (SiC) traction inverter power modules. Similarly, commercial solutions already benefit from SiC traction inverter in terms of performance as well as in terms of economical investment. Notwithstanding, the good features there are some issues due to the fast switching ability of SiC MOSFET. In such a contest, is the fine-tuning of a proper simulation tool is the first for an optimal design of the conversion systems, especially, the snubbers necessary to mitigate turn-off overvoltage and ringing of SiC MOSFET devices. In this perspective, this paper combines Ansys Q3D analysis and Spice simulations to foresee the SiC MOSFET Power Module waveforms. The experimental results have highlighted a good accuracy of the tool at predicting the performance of the module and the boundary operating conditions.

A non-invasive temperature sensing method for high-voltage SiC MOSFET chips based on the measurement of light emission during reverse conduction is proposed. The method is based on a compact sensing circuit that can be easily embedded in the package, allowing online temperature estimation. The effectiveness of the circuit has been confirmed by the analysis of a commercial SiC power module. The proposed temperature sensing strategy is fast, inexpensive, accurate, and non-invasive.

In this paper, on-state dynamic drain source resistance (R DS(ON) ) phenomenon in GaN based power switches is analyzed. Dynamic R DS(ON) may increase the power losses in converters, thus reducing the benefits of using GaN power devices in this field. The operating parameters having an impact on dynamic R DS(ON) are investigated by analyzing the research works available so far from industry and academia. The objective of this work is to highlight the key operating parameters that influence this phenomenon, in order to give useful information to designers. Another objective is the identification of the lack of information on the topic, thus suggesting the analysis useful for an all-embracing understanding of the influence on dynamic R DS(ON) due to the different operating conditions. To these aims, the collected data are harmonized since the variety of test conditions, the different methods adopted to report the results and to obtain them. The comparison has highlighted that the working frequency is the main factor influencing the dynamic R DS(ON) . Moreover, the analysis has drawn attention to the necessity to make extensive experimental analyses on various technologies types and mission profiles. Finally, the main research topic to be properly investigated concerns the deep analysis of the correlations among the parameters which affect the dynamic R DS(ON) .

In lighting system design, the LED light bulb technology is gaining more and more advantages in comparison to other previous solutions. On the other hand, the designers of lighting systems have to face the specific problems created by this technology in terms of deterioration of the power quality on the mains. The knowledge of lamp electrical models is a key point for the optimal design of the lighting systems but such models are not provided by the manufactures. Moreover, the voltage on the mains may vary along the day due to the load fluctuation as well as due to the variation of the power generated by distributed renewable resources. Consequently, suitable electrical models have to be able at emulating the lamp behavior according to the voltage variability. The paper proposes an equivalent electrical circuit of LED light bulb. The components of the model are identified by means of simple electrical measurements. In particular, the circuit enables to emulate the current waveform in the case of network voltage variability. The validation has highlighted that the simulated currents waveforms have a good matching with the experimental data obtained in presence of distorted voltage on the mains (provided that the voltage THD is compliant with IEEE-Std-519). The validation has been performed also at voltage values different from the ones used for the components identification.

Power device modeling plays an important role at the design stage of power conversions systems, especially in the automotive and aircraft sectors. In this context, it is important to obtain in short time an accurate model that account for the mutual interaction of thermal and electrical quantities. The behavioral model is the best approach because it consists of a set of equations that emulates the device behavior at terminals level and can be easily implemented in a SPICE simulation tool, largely adopted both in industrial and academic contexts. The major issue of the behavioral model is to choose the equations parameters such that the simulations results fit the measurement data. In this paper, this problem is tackled by means of a particle swarm optimization algorithm. It is applied to automatically find the optimal parameters for an accurate behavioral model of an automotive grade SiC MOSFET that properly fits the datasheet curves. The comparison between the waveforms obtained by experimental tests and the SPICE simulations in a double test has confirmed the accuracy of the model.

The Si devices have achieved their theoretical limits with the increasing of the switching frequency. The innovative GaN power switches present many advantages in power conversion systems, especially in terms of efficiency and size. The use of GaN transistors will be strongly exploited in the automotive applications due to these features. Indeed, the socalled point of loads require an increasing attention, in particular for the 48V-12V electric system architectures. In this paper the reduction of the energy losses achievable thanks to commercial GaN devices is analyzed by a simple circuit model. The effectiveness of the model is validated by experimental measurements in a synchronous buck converter. The results confirm that a remarkable efficiency improvement with the current GaN technology may be already reached.

The Gallium Nitride (GaN) power switches may offer significant improvement in quasi resonant (QR) Flyback converters, e.g. an enhanced conversion efficiency and reduced volume. This work investigates the performance of Silicon superjunction (SJ) MOSFET and GaN devices exploited in a QR Flyback topology. Firstly, the QR converter design has been performed by considering the characteristics of a SJ MOSFET device as well as the passive elements and the related PWM controller. After that, a level shifter has been adopted to carry out the analysis with a GaN device. The level shifter provides the proper gate voltage supply, thus avoiding damage and device failure due to unadapt driving conditions of the device. The experimental results have shown a performance improvement in comparison to the power SJ MOSFET, with an increase in the efficiency (0.8%) due to the reduction of the switching power losses, despite the converter has not been optimized for the GaN power switch. The converter has not been optimized for the GaN in order to dispel any doubt about the fact that any efficiency improvement is obtained only thanks to the GaN.

International guidelines have defined various aspects relating to electric vehicles that this paper presents briefly. International directives promote the adoption of electric vehicles, but do not plan an adequate revision of the electric distribution and of its present regulation to make efficient the promotion. The vehicle charging systems achieve to absorb electric power from 20 kW up to 200 kW and will have a great penetration in every area of use. Therefore, mainly in residential areas and in areas of public activities such as hotels, restaurants, public entertainment venues, charging systems for a number of dozens / hundreds of vehicles, they will have a significant impact on the power distribution system, pose problems of interference among the load areas, of safety for users and of service continuity to guarantee batteries topup. This paper discusses and suggests some solutions to these problems.

There is an increasing interest in developing unmanned aerial vehicles (UAVs) for small size objects delivering. The efficiency and cost of the on board power converters are important aspects for their rapid spreading. Moreover, lifetime, safety, and reliability of the converter in the powertrain are crucial. In this perspective, voltage overshoots and oscillations due to the parasitic phenomena are important stresses to be cared. In this work, their effects in a half bridge converter have been analyzed since it can represent a leg of a three phase inverter feeding a motor of the UAV. Automotive grade super junction (SJ) MOSFET has been considered because it presents high reliability level with increased lifetime expectancy and it is less subjected to overshoot and oscillation issues. Moreover, SJ MOSFET is a mature technology with better cost. In this paper, an extensive parametric analysis has been carried out by performing several LTspice simulations to highlight the effects of the parasitic phenomena on both the drain source-voltage and efficiency. The results have been firstly validated, then useful design constraints have been identified.

Nowadays, there is a great research effort in the field of electric vehicles. In such a context, SiC power modules play a key role for their effective and widespread diffusion especially due to their ability at improving the performance of the traction inverter. The advantages and issues related to SiC traction modules are analysed in this work giving also guidelines for viable solutions. More specifically, electrical and thermal problems, safety and reliability issues, challenges from device paralleling and module layout as well as power efficiency, have been investigated. The aim of this work is to collect all these aspects that must be carefully considered at the SiC power modules design stage. The main merit of this overview is their analysis performed by means of on field experience, in terms of experimental tests, finite element analysis, and circuit simulations.

In this paper, a stop-band filter realized by a high impedance surface for reducing electromagnetic interference from printed circuit boards is studied. Starting from an existing high impedance surface, Design of Experiments techniques and numerical simulations were employed to analyze the effect of its geometrical parameters on the desired forbidden band-gap of the filter. Finally, an improved high impedance surface is proposed.

The increasing demand of electronic systems in car electrification as well as in IoT (internet of thing) applications requires power supply with large power output, high efficiency, and small size factor. In this framework, the main topologies used for telecom switch-mode-power-supply (SMPS) have been investigated in this paper. Performance and reliability of the SMPS are mainly related to the MOSFET characteristics, and a primary aspect of such high-level applications is to ensure the service continuity. The new products of super junction (SJ) MOSFETs with very fast diode are the best candidate to match the above expectations. This work describes the reasons underlying the performance improvement and presents the experimental results confirming that SJ MOSFETs with very fast diode is the suitable technology to be used for telecom zero voltage switching SMPS.

In the last years the aerospace industry has put a growing effort to develop on-board electrification. The difficulties, which have emerged to implement the transition to the future aircraft, concern above all the constraints to be respected for aircraft applications (reliability, small size, reduced maintenance time, etc.). The present paper proposes to analyze and discuss the power devices and suitable converter topologies that bring the requirements of the airborne applications, especially devoted to match with the reliability and performance issues.

In recent years the increase of portable devices has led to the need for supply systems from several energy sources. In some case, it is necessary to manage very low input voltage values (below 1V). The conversion of the energy from these very low voltage sources requires special design because topologies capable of raising the voltage in an appropriate mode with high efficiency are necessary. In these kinds of electronic consumer applications, the increase of the autonomy is the one of the main objectives to reach. The aim of this paper is the investigation of a synchronous boost converter with coupled inductors to adapt the voltage level from very low voltage sources. High performance low voltage MOSFETs are applied with an optimized figure of merit. Simulation and experimental results are carried out to validate the effectiveness of the proposed circuit solution.

Super junction (SJ) MOSFET is a well-established device in high-density and high frequency power conversion. Soft-switching techniques are usually adopted at high frequency to reduce the power losses into the power devices. However, new challenging issues appear always when the paradigm changes. In fact, unexpected heating and efficiency reduction due to $\boldsymbol{C}_{\mathbf{oss}}$ related phenomena are key issues to be faced when SJ MOSFETs are adopted in high-frequency soft-switching applications. The phenomenon appears when large voltage transients are applied to the drain-source terminals as in the case of soft-switching applications. This paper provides analysis of the electrical hysteresis, and proposes an equivalent circuit that may model such a behavior in case of SJ MOSFETs. The loss model of $\boldsymbol{C}_{\mathbf{oss}}$ has been validated by comparing the measurements with the simulation runs performed by means of the Simulink package.

Industrial interest is directed towards the development of Light-emitting diode (LED) and compact fluorescent (CF) lamps. Their electrical models are very useful for the design of a lighting system because they enable to design the power systems and to compare the efficiency of different solutions. In this perspective, it is useful to analyze the behavior of the lamps as a consequence of the variation of the supply voltage in order to find a circuit model able in emulating the absorbed current. Therefore, some LED and CF lamps have been tested under variable voltage, and their LT Spice model has been obtained. The experimental evidence suggests that using a constant interpolation for the current data provides results similar to the linear one for CF. For many LED lamps it is necessary the use of linear interpolation for obtaining an error comparable with CF lamps, while constant interpolation usually provides poor estimation of the performance.

High switching frequencies in power converters allow to use small-size passive components that, in turn, means high-density (kW/kg) power conversion. The use of silicon MOSFETs manufactured with super junction technology is an additional feature towards the achievement of very high-density converters. The concurrent factors of increased switching frequency and power density may lead to thermal issues to be faced. Aiming to reduce the overall power losses, soft switching techniques are adopted to reduce dramatically the switching power losses, thus increasing the efficiency. The application of super junction (SJ) MOSFETs in soft-switching based conversion schemes has revealed unexpected power losses due to the dielectric hysteresis phenomenon into the parasitic output capacitance Coss of the MOSFET. In this respect, the experimental evidence has proved that there is a very large performance difference among the devices available into the market. This paper studies the Coss power losses that have been experimentally measured, modeled and simulated by a PSpice package. The proposed model is a nonlinear resistor whose average value is equal to the equivalent series resistance calculated from the experimental hysteresis loop (Q- V characteristic) and the related power losses at a given switching frequency.

Smart agriculture, representing one of the use cases for Industry 4.0, encounters some deployment problems in wide rural areas where neither telecommunications infrastructure, nor a local power grid is available. For this reason, this paper proposes a comprehensive platform constituted by a Flying Ad hoc NETwork (FANET) to provide connectivity, and a 5G network access node equipped with MEC facilities to run software applications at the edge of the network. Power supply for the 5G base station, the drones to be periodically recharged and the servers in the data center equipped with MEC facilities is realized by an electrical hybrid generator. An analytical model of the whole system is also defined to capture all the above issues, and supporting the design of the proposed system.

This paper presents a modulation technique based on a time partition obtained by first kind Chebyshev polynomials zeros suitable for single phase cascaded H-bridge five-level inverters. After a detailed mathematical description of the method, some simulation results and some comparisons among the proposed method, level-shifted and phase-shifted pulse-width modulation techniques are presented and discussed. It can be observed that proposed technique outperforms the above mentioned methods in terms of total harmonic distortion factor.

Nowadays, the light-emitting diode (LED) bulb is one of the preferred choice in lighting system design. Electrical models of the LED lamps have to consider their nonlinear behavior involving current distortion on the mains. With this purpose, an equivalent electrical circuit emulating the current drawn by a LED Bulbs is carried out. In this work, different lamps have been tested under variable supply voltage. The comparison between the simulations performed by means of PSpice and the experimental measurements has highlighted that linear interpolation for the amplitude of each harmonic current, as function of the voltage on the main, provides a good estimation of the total current waveform.

Drone market is in the infancy stage although it is rapidly growing in the last years. In the next future, drones will be largely adopted in traditional economy sectors as well as for supporting emerging technologies. The main application problem is the limited flying range and, consequently, the need of performing many battery recharges during the time interval a drone performs its task. The large diffusion of recharging stations is a key factor in view of persistent operation without humans' intervention. This scenario leads promising business opportunities such as the development of a network of recharge stations on the roof of buildings. In this perspective, resonant wireless power transfer is the best enabling technology for the drone recharge station. One technical issue to be dealt with is the variability of the coupling factor due to the various misalignments that can occur between a drone and the supplying pad where it lands. This work proposes a current tuning mechanism that compensates for this variability in a single-inverter multi-pad charging station. The simulations performed through the Simscape Power Systems module in Simulink has confirmed the effectiveness of the used approach.

Today the technologies regarding the solid-state devices are in huge development. Well-established Silicon power devices in the field of the power conversion belong to several families having a large range of rated value of currents and voltages. The new entries are innovative devices exploiting the good properties of wide band gap materials, like the Silicon Carbide and the Gallium Arsenide. Industrial and academic research interests focus on the development of well-established and new devices, looking to obtain good performances and enhanced energy savings. This paper explores and discusses the application of the power devices in aviation, highlighting the crucial aspects and the challenges to deal with for a full implementation of the more electric aircraft paradigm.

As a common practice into the use of silicon semiconductor devices, the capability of a discrete power switch may by augmented by using the parallel connection of several single MOSFETs. This paper deals with the main results of an experimental investigation about the issues linked to devices and circuit mismatches, regarding the parallel operations of Silicon Carbide (SiC) MOSFETs. Implementations into the state-of-the-art of paralleled SiC, which are used in switching converter, use discrete devices widely packaged as TO-220 or TO-247. In this case both the external and internal parasitic parameters have to be well bounded not to penalize the overall performance. Based on the experimental validation of paralleled discrete devices, this investigation firstly focuses on the main electrical parameters affecting the performance of the paralleled switches. Then, the influence of the circuit mismatch on paralleled SiC MOSFETs is investigated by selectively setting the value of the parameter under investigation (i.e. the external gate resistance, the drain stray inductances, the common source stray inductances). The impact of the “Kelvin source” connection, that is tailored to minimize the negative feedback of the source stray inductances into the voltage gate command, is also evaluated in terms of effects on the current unbalance mitigation, and about the power losses during the switching.

For a decade to now, lighting with LED lamp technology has rapidly established itself in the market, both for domestic use and for industrial use, becoming in fact a viable alternative to fluorescent lamp technology. Industrial research interests focus on this LED lamp technology, which is steadily in development, presenting continuous improvements and considerable advantages compared to the fluorescent lamps. It should be noted that both technologies introduce a high harmonic content in the power supply network, and therefore represent a non-linear load for the mains. The present work aims to analyze and study the electrical and photometric characteristics of the two technologies. For this purpose eight lamp types, four CFL and four LED lamps are tested, through laboratory measurements and detailed analyses. The photometric and electrical quantities of the lamps are then detected, and subsequently the variations undergone by these quantities with the aging of the lamps are verified and discussed. The measurements of the photometric quantities are performed according to the EN 13032–1: 2004 standard, and the tests on the electrical quantities aim to evaluate the harmonic content, and check if it meets the IEC 61000–3-2 standard.