Dimosthenis Peftitsis

Dimosthenis Peftitsis
Norwegian University of Science and Technology | NTNU · Department of Electrical Power Engineering

PhD

About

92
Publications
50,619
Reads
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1,605
Citations
Introduction
Dimosthenis Peftitsis currently works at the Department of Electrical Power Engineering, Norwegian University of Science and Technology.
Additional affiliations
May 2016 - present
Norwegian University of Science and Technology
Position
  • Professor (Associate)
October 2014 - March 2016
ETH Zurich
Position
  • PostDoc Position
July 2013 - September 2014
KTH Royal Institute of Technology
Position
  • PostDoc Position

Publications

Publications (92)
Article
The lower conduction power losses and the positive temperature coefficient that favours parallel connections, make Silicon Carbide (SiC) Metal Oxide Semiconductor Field-Effect Transistors (MOSFETs) to be an excellent replacement of existing Silicon Insulated Gate Bipolar Transistors (IGBTs) technology. These characteristics combined with high switc...
Preprint
Full-text available
The lower conduction power losses and the positive temperature coefficient that favours parallel connections, make Silicon Carbide (SiC) metal oxide semiconductor field-effect transistors (MOSFETs) to be an excellent replacement of existing Silicon insulated gate bipolar transistors (IGBTs) technology. These characteristics combined with high switc...
Article
Full-text available
The paper presents an empirical study conducted in the context of an advanced power electronics design course in a technical university. In selected points of the lectures formative assessments were introduced and supported by the use of clickers. The purpose of the article is to examine students’ perceptions of the effectiveness of clickers use. I...
Article
Full-text available
The implementation of a dual electric system that is capable of operating with either constant current and variable voltage, or constant voltage and variable current appliances, is one of the possible options to solve low-intensity stochastic energy utilization problems from renewable energy sources. This research paper analyzes the potential benef...
Article
Solid-state DC breakers is the ultimate technology for protecting medium-voltage DC grids having equipment vulnerable to excessive fault-current stress, due to the very short fault-clearing times. A typical implementation of such breakers is based on insulated gate bipolar transistors (IGBTs). However, as the rated voltage of the grid increases, se...
Article
This paper presents an isolated single-stage AC-DC high-frequency link full-bridge cycloconverter (HFLC) with high conversion ratio. Despite certain advantages, such topologies generally suffer from transformer leakage inductance problems and lack of effective modulation methods, particularly in the AC-DC operation mode. In this study, for the inpu...
Conference Paper
Abstract: This paper presents a detailed analysis of a series LC resonant isolated current source converter (SR-CSC) with the focus on a buck operation mode. Topologies of this type are generally proposed for PV, fuel cell, battery charging or DC microgrid applications. The switching processes on the example of the full-bridge topology are describe...
Conference Paper
For the design of a power converter with energy recovery operation, a trade-off is related to the choice of the output and dc-link voltages, which, in turn, determines the choice of the blocking voltage capability of the semiconductor switches. This work investigates the possibility to optimise the capital and operation costs and the performance (r...
Article
Full-text available
Abstract Normally‐ON silicon carbide junction‐field‐effect transistors have a simple design and exhibit advantageous performance in terms of losses, elevated junction temperatures and high switching frequencies. However, under a loss of power to their gate, normally‐ON junction‐field‐effect transistors are subject to a shoot‐through situation, whic...
Article
Full-text available
Recent trends in building energy systems such as local renewable energy generation have created a distinct demand for energy storage systems to reduce the influence and dependency on the electric power grid. Under the current market conditions, a range of commercially available residential energy storage systems with batteries has been produced. Th...
Conference Paper
This paper proposes an energy management control scheme for controlling the energy flow in a modular and scalable DC/DC converter design with energy recovery, based on a fundamental building block structure. The overall design in terms of control, number and configuration of the building blocks for optimised electrical operation is presented. Serie...
Article
Full-text available
Abstract Lifetime models of high‐power Insulated Gate Bipolar Transistors modules express the number of cycles to end of life as a function of stress parameters. These models are normally developed based on experimental data from accelerated power‐cycling tests performed at predefined temperature stress conditions as, for example, with temperature...
Conference Paper
This paper proposes an automatic and self-powered solid-state DC circuit breaker employing normally-ON silicon carbide junction-field-effect transistors. These devices exhibit low power conduction losses compared to silicon counterparts, which makes them suitable for solid-state DC circuit breakers. The proposed circuit not only eliminates the need...
Conference Paper
This paper presents results from experimental tests intended to assess the validity of linear damage superposition using Miner's rule for IGBT power modules. Such validity is crucial, for example, when applying Miner's rule in combination with power cycling lifetime models for estimating converter design lifetime. The linear combination of damage i...
Conference Paper
This paper presents simulation results on the magnetic design of a high-frequency isolation transformer using solid insulation. The transformer is intended for auxiliary power supplies in medium-voltage converters. Thus, the coupling capacitance must be limited while ensuring the target self-inductance of the transformer windings. Integration of th...
Conference Paper
This paper presents the design and operating principles of a novel current-source gate driver for Silicon Carbide metal oxide semiconductor field-effect transistors with adaptive functionalities that aims to improve controllability of and compared to conventional totem-pole voltage source gate drivers. The proposed gate driver is capable of providi...
Conference Paper
The advantages of using silicon carbide (SiC) devices can only be utilized if they are properly packaged. Existing packaging technology is based on silicon (Si) packaging technology. However, SiC semiconductor devices are much more sensitive to the stray inductance present in the module layout due to their considerably faster dynamics. This can lea...
Conference Paper
Due to the superior material characteristics of Silicon Carbide (SiC), the use of SiC MOSFETs enables higher system power density or efficiency depending on the design perspective. To identify the improvement potential in the operation of a device, precise characterization is crucial. This paper presents a flexible and easily reconfigurable test se...
Conference Paper
Two failure mechanisms can generally be identified by means of accelerated power cycling tests on IGBT power modules: bond-wire lift-off and die-solder delamination. Aging associated to bond-wire lift-off is detected by monitoring the increase of collector-emitter voltage while aging linked to die-solder delamination is detected by observing the in...
Conference Paper
Isolated dual active bridge (DAB) converter is one of the widely researched DC-DC converters nowadays. This paper presents a detailed analysis of the reflow power in the DAB converter due to the circulating inductor current with single phase shift (SPS) modulation. In addition, a novel computational process of the leakage inductance of the transfor...
Article
Full-text available
This paper presents a design and performance evaluation of three different overvoltage suppression circuits employed in a solid-state circuit breaker for medium- to high-power and low- to medium-voltage DC grids. The evaluated criteria are the requirements for passive components, as well as the breaker performance in terms of peak switch overvoltag...
Article
Full-text available
This letter presents a passive snubber circuit for high-frequency link cycloconverters, which typically suffer from voltage oscillations across matrix-stage semiconductor devices. The proposed passive snubber allows for effective damping of the oscillations and reduction of the peak voltage stress. It is based on an auxiliary transformer and a diod...
Article
This paper presents a high gain pure sine-wave inverter based on the full-bridge DC-AC high-frequency (HF) link cycloconverter topology for telecom or general-purpose applications. The improved quasi-resonant modulation method allows reduction of ringing and turn-off losses of the dc-side switches. This is achieved with minimal energy circulation a...
Article
This paper investigates the insulation design for printed, planar, coreless, and high-frequency transformers with high isolation-voltage. By using finite element analysis on 2D axial-symmetry, the transformer circuit parameters and electric field distribution are modelled and estimated. Several transformers are designed for an operating frequency o...
Article
This paper presents improvements to a SPICE model for a commercially available SiC MOSFET to avoid convergence errors while still providing reliable simulation results. Functionality in the internal part of the model that shapes the transconductance of the device according to its junction temperature and gate-source voltage dependency has been impr...
Article
Statistical lifetime models for high-power IGBTs are developed based on results from power-cycling experiments, and relate lifetime expectancy to the well-defined conditions of a laboratory experiment. In most cases, predefined cyclic-stress conditions are repeatedly applied, until the power device under test reaches its end of life. However, in re...
Article
This article presents the design and optimization of a suitable topology for an isolated dc–dc auxiliary power supply with high isolation voltage and low coupling capacitance. The converter consists of a GaN HEMT inverter operating at 6.78 MHz, an LCC resonance tank, and a class-E low d v /d t rectifier. Furthermore, the galvanic isolation is i...
Conference Paper
This paper presents improvements to a SPICE model for a commercially available SiC MOSFET to avoid convergence errors while still providing reliable simulation results. Functionality in the internal part of the model that shapes the transconductance of the device according to its junction temperature and gate-source voltage dependency has been impr...
Conference Paper
Full-text available
This paper investigates the impact of several design parameters on the electro-thermal performance of a solid-state circuit breaker (CB) for medium voltage DC (MVDC) grids. The parameters studied are the cooling system design along with the ambient temperature under steady-state. The impact of the current limiting inductor and the threshold current...
Conference Paper
Electric energy distribution using medium voltage DC (MVDC) enables an advantageous performance compared to the state-of-the-art MVAC counterparts. Among others, a crucial challenge currently is related to the need for developing high-performance protection schemes against DC short-circuits and, thus, to prevent severe conditions of electric and th...
Conference Paper
Full-text available
This paper presents the fundamental system components of medium-voltage direct current (MVDC) grids, including an overview of power electronic converters and protection schemes against DC fault currents. In addition to this, the lack of standardization and the development of efficient and reliable circuit breakers (CBs), which are today considered...
Conference Paper
Full-text available
This paper investigates the power cycling methodology for reliability testing of SiC metal-oxide-semiconductor field-effect transistors (MOSFETs). Dedicated test benches were designed and built to study this issue. The results indicate that power cycling of SiC MOSFETs is affected by threshold voltage instability. A proposal for reducing the influe...
Article
Full-text available
The breakdown voltages of the currently available 1.2 and 1.7-kV classes Silicon Carbide (SiC) transistors are not sufficient to operate under medium blocking voltages. On the other hand, the fabrication yields of the available high-voltage SiC transistors are still low, resulting in low current capabilities. Series-connection of several individual...
Article
Full-text available
Silicon carbide (SiC) power transistors have started gaining significant importance in various application areas of power electronics. During the last decade, SiC power transistors were counted not only as a potential, but also more importantly as an alternative to silicon counterparts in applications where high efficiency, high switching frequenci...
Article
Full-text available
This paper presents the design process of a 312-kVA three-phase silicon carbide inverter using ten parallel-connected metal-oxide-semiconductor field-effect-transistor power modules in each phase leg. The design processes of the gate-drive circuits with short-circuit protection and power circuit layout are also presented. Measurements in order to e...
Article
Full-text available
An experimental analysis of the behavior under short-circuit conditions of three different silicon-carbide (SiC) 1200-V power devices is presented. It is found that all devices take up a substantial voltage, which is favorable for detection of short circuits. A transient thermal device simulation was performed to determine the temperature stress on...
Article
Full-text available
A circuit solution to the normally–ON property of the normally–ON silicon carbide junction field–effect transistor, namely the self–powered gate driver, has been recently proposed. This paper sheds some light on the design process of the self–powered gate driver concept as well as limitations from the system perspective. It is experimentally shown...
Conference Paper
Full-text available
This paper presents the design process of a 312 kVA three-phase silicon carbide inverter using ten parallel-connected metal-oxide-semiconductor field-effect-transistor power modules in each phase-leg. The design processes of the gate-drive circuits with short-circuit protection and the power circuit layout are also presented. Electrical measurement...
Conference Paper
Active control of the dead-time in a SLR converter is in this paper shown to be of great importance. The efficiency of the full-bridge will increase if the dead-time control is made in the right way. Different control algorithms are shown to work well for different power switches. For the SiC MOSFET and the SiC BJT the control algorithms are tested...
Chapter
This chapter presents recent advances in power semiconductors technology with special attention on wide bandgap (WBG) transistors. A short introduction to the state-of-the-art Silicon power devices is given, and the characteristics of the various SiC power switches are also described. Design considerations of gate and base-drive circuits for variou...
Article
Full-text available
Soft-switching converters equipped with insulated gate bipolar transistors (IGBTs) in silicon (Si) have to be dimensioned with respect to additional losses due to the dynamic conduction losses originating from the conductivity modulation lag. Replacing the IGBTs with emerging silicon carbide (SiC) transistors could reduce not only the dynamic condu...
Article
Full-text available
Operation of parallel-connected 4H-SiC vertical junction field effect transistors (VJFETs) from SemiSouth is modeled using numerical simulations and experimentally verified. The unbalanced current waveforms of parallel-connected VJFETs are investigated with respect to the spread in the critical parameters of the device structure and to the influenc...
Article
Full-text available
Silicon carbide (SiC) bipolar junction transistors (BJTs) require a continuous base current in the on-state. This base current is usually made constant and is corresponding to the maximum collector current and maximum junction temperature that is foreseen in a certain application. In this paper, a discretized proportional base driver is proposed wh...
Article
Full-text available
Silicon Carbide high-power modules populated with several parallel-connected junction field-effect transistors must be driven properly. Parasitic elements could act as drawbacks in order to achieve fast and oscillation-free switching performance, which are the main goals. These two requirements are related closely to the design of the gate-drive un...
Article
Full-text available
This paper describes issues related to parallel connection of SiC bipolar junction transistors (BJTs) in discrete packages. The devices are applied in a high-frequency dc/dc boost converter where the switching losses significantly exceed the conduction losses. The design and construction of the converter is discussed with special emphasis on succes...
Conference Paper
Full-text available
Parallel connection of silicon carbide power modules is a possible solution in order to reach higher current ratings. Nevertheless, it must be done appropriately to ensure a feasible operation of the parallel-connected power modules. High switching speeds are desired in order to achieve high efficiencies in medium and high-power applications but pa...
Article
Full-text available
The message of this paper is that the silicon carbide power transistors of today are good enough to design converters with efficiencies and switching speeds beyond comparison with corresponding technology in silicon. This is the time to act. Only in the highest power range the devices are missing. Another important step towards high powers is to fi...
Article
The 4H-SiC Schottky barrier diodes for high temperature operation over 200 °C have been developed using buried grids formed by implantation. Compared to a conventional JBS-type SBD with surface grid (SG), JBS-type SBD with buried grid (BG) has significantly reduced leakage current at reverse bias due to a better field shielding of the Schottky cont...
Conference Paper
Full-text available
An Experimental performance analysis of a parallel connection of two 1200/80 MΩ silicon carbide SiC MOSFETs is presented. Static parallel connection was found to be unproblematic. The switching performance of several pairs of parallel-connected MOSFETs is shown employing a common simple totem-pole driver. Good transient current sharing and high-spe...