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  • 1.
    Colmenares, Juan
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    Switching Performance of Parallel-Connected Power Modules with SiC MOSFETs2014Inngår i: 2014 International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014, IEEE conference proceedings, 2014, s. 3712-3717Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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 parasitic elements may give rise to a non-uniform current sharing during turn-on and turn-off, leading to non-uniformly distributed switching losses. This paper presents the switching performance of parallel-connected power modules populated with several silicon carbide metal-oxide-semiconductor field-effect-transistors chips. It is experimentally shown that turn-on and turn-off switching times of approximately 50 ns and 100 ns, respectively, can be reached, while an acceptably uniform transient current sharing is obtained. Moreover, based on the obtained results, an efficiency of approximately 99.35% for a three-phase converter rated at 312 kVA with a switching frequency of 20 kHz can be estimated.

  • 2.
    Colmenares, Juan
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Dual-function gate driver for a power module with SiC junction field transistors2013Inngår i: 2013 IEEE ECCE Asia Downunder - 5th IEEE Annual International Energy Conversion Congress and Exhibition, IEEE ECCE Asia 2013, IEEE , 2013, s. 245-250Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Driving a high-power module which is populated with several parallel-connected silicon carbide junction field-effect transistor chips must be done appropriately. Parasitic elements may give rise to oscillations during turn-on and turn-off. Fast and oscillation-free switching performance is desired in order to achieve a high efficiency. The key-issue in order to fulfill these two requirements is the design of a sophisticated gate driver. This paper proposes a dual-function gate-drive unit which is able to switch the module with an acceptable speed without letting the current and voltage suffer from significant oscillations. It is experimentally shown that turn-on and turn-off switching times of approximately 140 ns and 165 ns respectively can be reached, while the magnitude of the current oscillations is kept at an acceptable level. Moreover, using the proposed gate driver an efficiency of approximately 99.6% is expected for a three-phase converter rated at 125 kVA and having a switching frequency of 2 kHz.

  • 3.
    Colmenares, Juan
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling. Warsaw University of Technology, Poland .
    Sadik, Diane-Perle
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Dual-Function Gate Driver for a Power Module With SiC Junction Field-Effect Transistors2014Inngår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 29, nr 5, s. 2367-2379Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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 unit, and they must be kept under certain limits when high efficiencies are targeted. This paper deeply investigates several versions of gate-drive units and proposes a dual-function gate-drive unit which is able to switch the module with an acceptable speed without letting the current suffer from significant oscillations. It is experimentally shown that turn-on and turn-off switching times of approximately 130 and 185 ns respectively can be reached, while the magnitude of the current oscillations is kept at an adequate level. Moreover, using the proposed gate driver an efficiency of approximately 99.7% is expected for a three-phase converter rated at 125 kVA and having a switching frequency of 2 kHz.

  • 4.
    Colmenares, Juan
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Tolstoy, Georg
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Sadik, Diane-Perle
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    High-efficiency three-phase inverter with SiC MOSFET power modules for motor-drive applications2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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 measurements in order to evaluate the performance of the gate-drive circuits have been performed using a double-pulse setup. Experimental results showing the electrical performance during steady-state operation of the power converter are also shown. Taking into account measured data, an efficiency of approximately 99.3% at the rated power has been estimated for the inverter.

  • 5.
    Lim, Jang-Kwon
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Bakowski, Mietek
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Analysis and Experimental Verification of the Influence of Fabrication Process Tolerances and Circuit Parasitics on Transient Current Sharing of Parallel-Connected SiC JFETs2014Inngår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 29, nr 5, s. 2180-2191Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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 influence of the parasitic inductances in the measurement circuit. The device structures are reconstructed based on scanning electron microscopy (SEM) analysis, electrical characterization, and device simulations. The doping concentration and profile depth of a p-grid formed by angular implantation are studied as main contributors that influence the variation of the on-state characteristics, and the threshold voltage of the experimental devices. It has been shown elsewhere that similar differences in p-grid also lead to differences in gate-source breakdown voltage. The switching performance of the parallel-connected JFETs is measured using single and double gate drivers in a double-pulse test and compared with simulations. The switched current and voltage waveforms from measurements are reproduced in simulation by introducing the parasitics. From the analysis, it is found that reasonable differences in doping levels and profiles of the p-grid give rise to significant differences in device parameters. However, even with these parameter differences and circuit asymmetries, it is possible to successfully operate parallel-connected VJFETs of this type.

  • 6.
    Lim, Jang-Kwon
    et al.
    Acreo.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Bakowski, Mietek
    Acreo.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Modeling of the impact of parameter spread on the switching performance of parallel-connected SiC VJFETs2013Inngår i: Materials Science Forum, Trans Tech Publications Inc., 2013, s. 1098-1102Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Operation of parallel-connected 4H-SiC VJFETs from SemiSouth was measured and modeled using numerical simulations. The unbalanced current waveforms in parallel-connected VJFETs were related to spread in the critical parameters of the device structure and to the influence of the parasitic inductances in the measurement circuit. The physical device structure was reconstructed based on SEM analysis, electrical characterization, and device simulations. The two hypothetical critical design parameters that were studied with respect to spread were the p-gate doping profile (Case 1) and the emitter doping (Case 2). Variation in both parameters could be related to variation in the emitter breakdown voltage, the on-state characteristics, and the threshold voltage of the experimental devices. The switching performance of the parallel-connected JFETs was measured using a single gate driver in a double pulse test and compared with simulations. In both investigated cases a very good agreement between measurements and simulations was obtained. The modeling of the transient performance relies on good reproduction of transfer characteristics and circuit parasitics.

  • 7.
    Lim, Jang-Kwon
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik. Acreo Swedish ICT AB, Sweden.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES).
    Sadik, Diane-Perle
    KTH, Skolan för elektro- och systemteknik (EES).
    Bakowski, M.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Evaluation of buried grid JBS diodes2014Inngår i: 15th International Conference on Silicon Carbide and Related Materials, ICSCRM 2013, Trans Tech Publications Inc., 2014, s. 804-807Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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 contact. By introducing the BG technology, the 1.7 kV diodes with an anode area 0.0024 cm2 (1 A) and 0.024 cm2 (10 A) were successfully fabricated, encapsulated in TO220 packages, and electrically evaluated. Two types of buried grid arrangement with different grid spacing dimensions were investigated. The measured IV characteristics were compared with simulation. The best fit was obtained with an active area of approximately 60% and 70% of the anode area in large and small devices, respectively. The measured values of the device capacitances were 1000 pF in large devices and 100 pF in small devices at zero bias. The capacitance values are proportional to the device area. The recovery behavior of big devices was measured in a double pulse tester and simulated. The recovery charge, Qc, was 18 nC and 24 nC in simulation and measurement, respectively. The fabricated BG JBS-type SBDs have a smaller maximum reverse recovery current compared to the commercial devices. No influence of the different grid spacing on the recovery charge was observed.

  • 8.
    Lim, Jang-Kwon
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Tolstoy, Georg
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Bakowski, Mietek
    Acreo, Kista.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Comparison of total losses of 1.2 kV SiC JFET and BJT in DC-DC converter including gate driver2011Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 679/680, s. 649-652Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The 1.2 kV SiC JFET and BJT devices have been investigated and compared with respect to total losses including the gate driver losses in a DC-DC converter configuration. The buried grid, Normally-on JFET devices with threshold voltage of -50 V and -10V are compared to BJT devices with ideal semiconductor and passivating insulator interface and an interface with surface recombination velocity of 4.5·104 cm/s yielding agreement to the reported experimental current gain values. The conduction losses of both types of devices are independent of the switching frequency while the switching losses are proportional to the switching frequency. The driver losses are proportional to the switching frequency in the JFET case but to a large extent independent of the switching frequency in the BJT case. The passivation of the emitter junction modeled here by surface recombination velocity has a significant impact on conduction losses and gate driver losses in the investigated BJT devices.

  • 9.
    Nee, Hans-Peter
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    Warsaw University of Technology.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Multi-chip circuit designs for silicon carbide power electronics2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    As the chip sizes of commercially available silicon carbide power transistors will remain smaller than for silicon counterpartsin the next five to ten years, multi-chip circuit designs will be necessary in order to reach power levels exceeding10 kW. In the present paper, therefore, experiences from parallel connected discrete devices, multi-chip modules,and parallel-connected multi-chip modules are presented. It is concluded that new multi-chip circuit designs are necessaryif the high switching speeds of silicon carbide power transistors should be exploited. In the opinion of the authors,each chip must be contacted by means of individual current paths, and internal bus bars conducting the whole current ofthe module must be avoided.

  • 10.
    Nee, Hans-Peter
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Tolstoy, Georg
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Colmenares, Juan
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Sadik, Diane
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Bakowski, Mietek
    Acreo Swedish ICT AB, Sweden.
    Lim, Jang-Kwon
    Acreo AB, Kista.
    Antonopoulos, Antonios
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Ängquist, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Zdanowski, Mariusz
    Warsaw University of Technology.
    High-Efficiency Power Conversion Using Silicon Carbide Power Electronics2013Inngår i: Proc. of International Conference on silicon carbide and related materials (ICSCRM) 2013, Miyazaki, Japan, Sept. 29–Oct. 4, 2013, Trans Tech Publications Inc., 2013, s. 1083-1088Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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 find new solutions for multi-chip circuit designs that are adapted to the high possible switching speeds of unipolar silicon carbide power transistors.

  • 11.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    On Gate Drivers and Applications of Normally-ON SiC JFETs2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In this thesis, various issues regarding normally-ON silicon carbide (SiC)Junction Field-Effect Transistors (JFETs) are treated. Silicon carbide powersemiconductor devices are able to operate at higher switching frequencies,higher efficiencies, and higher temperatures compared to silicon counterparts.From a system perspective, these three advantages of silicon carbide can determinethe three possible design directions: high efficiency, high switchingfrequency, and high temperature.The structure designs of the commercially-available SiC power transistorsalong with a variety of macroscopic characteristics are presented. Apart fromthe common design and performance problems, each of these devices suffersfrom different issues and challenges which must be dealt with in order to pavethe way for mass production. Moreover, the expected characteristics of thefuture silicon carbide devices are briefly discussed. The presented investigationreveals that, from the system point-of-view, the normally-ON JFET isone of the most challenging silicon carbide devices. There are basically twoJFET designs which were proposed during the last years and they are bothconsidered.The state-of-the-art gate driver for normally-ON SiC JFETs, which wasproposed a few years ago is briefly described. Using this gate driver, theswitching performance of both Junction Field-Effect Transistor designs wasexperimentally investigated.Considering the current development state of the available normally-ONSiC JFETs, the only way to reach higher current rating is to parallel-connecteither single-chip discrete devices or to build multichip modules. Four deviceparameters as well as the stray inductances of the circuit layout might affectthe feasibility of parallel connection. The static and dynamic performance ofvarious combinations of parallel-connected normally-ON JFETs were experimentallyinvestigated using two different gate-driver configurations.A self-powered gate driver for normally-ON SiC JFETs, which is basicallya circuit solution to the “normally-ON problem” is also shown. This gatedriver is both able to turn OFF the shoot-through current during the startupprocess, while it also supplies the steady-state power to the gate-drivecircuit. From experiments, it has been shown that in a half-bridge converterconsisting of normally-ON SiC JFETs, the shoot-through current is turnedOFF within approximately 20 μs.Last but not least, the potential benefits of employing normally-ON SiCJFETs in future power electronics applications is also presented. In particular,it has been shown that using normally-ON JFETs efficiencies equal 99.8% and99.6% might be achieved for a 350 MW modular multilevel converter and a40 kVA three-phase two-level voltage source converter, respectively.Conclusions and suggestions for future work are given in the last chapterof this thesis.

  • 12.
    Peftitsis, Dimosthenis
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Adamidis, Georgios
    Fyntanakis, Athanasios
    Modulation of Three Phase Rectifier in Connection With PMSG for Maximum Energy Extraction2009Inngår i: 2009 13th European Conference on Power Electronics and Applications, EPE '09, IEEE , 2009, s. 1197-1206Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a Maximum Power Point Tracking (MPPT) method which is applied on a Wind Turbine with Permanent Magnet Synchronous Generator (PMSG). A three-phase Switched Mode Rectifier (SMR) is connected with the three phase output of the PMSG. The SMR employs a modulation strategy which is based on the Space Vector Modulation (SVM) technique. Thus, the three phase input voltage is divided in six equal intervals with respect to the zero crossing of the phase voltage and only two switches are switching in each one. A duty ratio D is introduced for each switch and is able to vary by Delta D in order to control the peak current through each phase. By controlling the three phase currents, it is possible to adjust the rotational speed of the PMSG and consequently the extracted power. The "Hill Climbing" algorithm has been used for achieving operation on the Maximum Power Point (MPP). The whole system has been designed and simulated using Matlab/Simulink and simulation results are shown for a variety of Delta D. Finally, a short discussion about the results is given.

  • 13.
    Peftitsis, Dimosthenis
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Baburske, R.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Lutz, J.
    Tolstoy, Georg
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Challenges regarding parallel connection of SiC JFETs2013Inngår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 28, nr 3, s. 1449-1463Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    State-of-the-art silicon carbide switches have current ratings that are not sufficiently high to be used in high-power converters. It is, therefore, necessary to connect several switches in parallel in order to reach sufficient current capabilities. An investigation of parallel-connected normally ON silicon carbide JFETs is presented in this paper. The device parameters that play the most important role for the parallel connection are the pinch-off voltage, the gate-source reverse breakdown voltage, the spread in the on-state resistances, and the variations in static transfer characteristics of the devices. Moreover, it is experimentally shown that a fifth factor affecting the parallel connection of the devices is the parasitic inductances of the circuit layout. The temperature dependence of the gate-source reverse breakdown voltages is analyzed for two different designs of silicon carbide JFETs. If the spread in the pinch-off and gate-source reverse breakdown voltages is sufficiently large, there might be no possibility for a stable off-state operation of a pair of transistors without forcing one of the gate voltages to exceed the breakdown voltage. A solution to this problem using individual gate circuits for the JFETs is given. The switching performance of two pairs of parallel-connected devices with different combinations of parameters is compared employing two different gate-driver configurations. Three different circuit layouts are considered and the effect of the parasitic inductances is experimentally investigated. It is found that using a single gate circuit for the two mismatched JFETs may improve the switching performance and therefore the distribution of the switching losses significantly. Based on the measured switching losses, it is also clear that regardless of the design of the gate drivers, the lowest total switching losses for the devices are obtained when they are symmetrically placed.

  • 14.
    Peftitsis, Dimosthenis
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Baburske, Roman
    Technische Universität Chemnitz.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Lutz, Josef
    Technische Universität Chemnitz.
    Tolstoy, Georg
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Challenges regarding parallel-connection of SiC JFETs2011Inngår i: IEEE 8th International Conference on Power Electronics and ECCE Asia (ICPE & ECCE), 2011: 'Green World with Power Electronics' / [ed] IEEE, 2011, s. 1095-1101Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Considering the present development of the available Silicon Carbide switches, their current ratings are so low that they cannot be used for high-power converters. It is therefore necessary to connect several switches in parallel in order to obtain sufficient current ratings. An investigation of parallel-connected normally-on Silicon Carbide Junction Field Effect Transistors is presented in this paper. The parameters that play the most important role for the parallel connection are the pinch-off and the gate-source breakdown voltages. The temperature dependency of those two voltages is analyzed based on the pnp structure of the device. If the spread in these parameters is sufficiently large there might be no possibility for a stable off-state operation of a pair of transistors without forcing one of the gate voltages to exceed the breakdown voltage, especially at high temperatures. A solution to this problem is given. The switching performance of two pairs of parallel-connected devices is compared with respect to their pinch-off voltages, and it is found that differences of approximately 25% in switching losses could result from a difference in the pinch-off voltage of 0.5 V.

  • 15.
    Peftitsis, Dimosthenis
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Lim, Jang-Kwon
    Acreo AB.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Tolstoy, Georg
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Experimental Comparison of Different Gate-Driver Configurations for Parallel-Connection of Normally-ON SiC JFETs2012Inngår i: 7th International Power Electronics and Motion Control Conference (IPEMC), 2012, IEEE conference proceedings, 2012, s. 16-22Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Due to the low current ratings of the currently available silicon carbide (SiC) switches they cannot be employed in high-power converters. Thus, it is necessary to parallel-connect several switches in order to reach higher current ratings. This paper presents an investigation of parallel-connected normally-on SiC junction field effect transistors. There are four crucial parameters affecting the effectiveness of the parallel-connected switches. However, the pinch-off voltage and the reverse breakdown voltage of the gates seem to be the most important parameters which affect the switching performance of the devices. In particular, the spread in these two parameters might affect the stable off-state operation of the switches. The switching performance and the switching losses of a pair of parallel-connected devices having different reverse breakdown voltages of the gates is investigated by employing three different gate-driver configurations. It is experimentally shown that using a single gate-driver circuit the switching performance of the parallel-connected devices is almost identical, while the total switching losses are lower compared to the other two configurations.

  • 16.
    Peftitsis, Dimosthenis
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Design Considerations for a Self-Powered Gate Driver for Normally-ON SiC Junction Field-Effect Transistors2013Inngår i: 2013 IEEE ECCE Asia Downunder - 5th IEEE Annual International Energy Conversion Congress and Exhibition, IEEE ECCE Asia 2013, IEEE conference proceedings, 2013, s. 251-257Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The very low on-state resistance, the voltagecontrolledgate, and the relative simplicity of fabrication of thenormally-ON silicon carbide junction field effect transistor makethis device the most important player among all state-of-theartsilicon carbide transistors. However, the normally-ON naturecounts as the main factor which keeps this device far frombeing considered as an alternative to the silicon insulated-gatebipolar transistor. A self-powered gate driver without externalpower supply for normally-ON silicon carbide junction field effecttransistors is presented in this paper. The proposed circuit isable to handle the shoot-through current when the devices aresubjected to the dc-link voltage by utilizing the energy associatedwith this current. On the other hand it supplies the necessarynegative gate-source voltage during the steady-state operation. Adetailed description of the operating states of the proposed circuitalong with various design considerations are presented. Fromexperiments which were performed in a half-bridge converter, itis shown that the shoot-through current can be turned off withinapproximately 15 s. Moreover, it is shown that the proposedgate driver can properly switch the devices.

  • 17.
    Peftitsis, Dimosthenis
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Self-powered gate driver for normally on silicon carbide junction field-effect transistors without external power supply2013Inngår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 28, nr 3, s. 1488-1501Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The very low on-state resistance, the voltage-controlled gate, and the relative simplicity of fabrication of the normally ON silicon carbide junction field-effect transistor (JFET) make this device the most important player among all state-of-the-art silicon carbide transistors. However, the normally ON nature counts as the main factor which keeps this device far from being considered as an alternative to the silicon insulated-gate bipolar transistor. A self-powered gate driver without external power supply for normally ON silicon carbide JFETs is presented in this paper. The proposed circuit is able to handle the short-circuit currents when the devices are subjected to the dc-link voltage by utilizing the energy associated with this current. On the other hand, it supplies the necessary negative gate-source voltage during the steady-state operation. A detailed description of the operating states in conjunction with a theoretical analysis of the proposed self-powered gate driver is presented. The first part of the experimental investigation has been performed when the proposed circuit is connected to a device which is directly subjected to the dc-link voltage. The second set of measurements were recorded when the self-powered gate-driver was employed as the driver of normally ON components in a half-bridge converter. From the experimental results, it is shown that the short-circuit current is cleared within approximately 20μs after the dc-link voltage is applied, while the power consumption when all devices are kept in the OFF state equals 0.37W. Moreover, it is experimentally shown that the proposed gate driver can properly switch when it is employed in a half-bridge converter. Finally, limitations regarding the range of the applications where the self-powered gate drive can efficiently operate are also discussed.

  • 18.
    Peftitsis, Dimosthenis
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Self-Powered Gate Driver for Normally-ON SiC JFETs: Design Considerations and System Limitations2014Inngår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 29, nr 10, s. 5129-5135Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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 letter 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 that the parameters of the self-powered gate driver must be chosen taking into account a tradeoff between a fast response and stable operation of the driver. Moreover, the influence of the shoot-through current in the fast activation of the self-powered gate driver is also presented.

  • 19.
    Peftitsis, Dimosthenis
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Tolstoy, Georg
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    Experimental comparison of dc-dc boost converters with SiC JFETs and SiC bipolar transistors2011Inngår i: Proceedings of the 2011-14th European Conference on Power Electronics and Applications (EPE 2011) / [ed] EPE Association, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An experimental performance comparison between SiC JFET and SiC BJT switches which are used as the main switch for a 2 kW dc/dc converter is presented. In order to perform a fair comparison and due to the different chip areas of these two SiC devices, they both operate under the same on-state losses. Moreover, the switching speeds of the gate and base drivers are approximately equal. It is experimentally shown that the SiC BJT is switching slightly faster than the SiC JFET under the same circuit conditions, while the driver loss for the SiC BJT is higher than for the JFET, especially at relatively low switching frequencies. Various experimental results dealing with the switching performance of the SiC devices and the power losses at different switching frequencies are presented. It is found that the BJT converter has a higher efficiency (99.0% measured at 50 kHz) that the JFET converter.

  • 20.
    Peftitsis, Dimosthenis
    et al.
    KTH, Skolan för elektro- och systemteknik (EES).
    Tolstoy, Georg
    KTH, Skolan för elektro- och systemteknik (EES).
    Antonopoulos, Antonios
    KTH, Skolan för elektro- och systemteknik (EES).
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES).
    Lim, Jang-Kwon
    Acreo, Kista.
    Bakowski, Mietek
    Acreo, Kista.
    Ängquist, Lennart
    KTH, Skolan för elektro- och systemteknik (EES).
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES).
    High-power modular multilevel converters with SiC JFETs2010Inngår i: 2010 IEEE Energy Conversion Congress and Exposition (ECCE) / [ed] IEEE, IEEE , 2010, s. 2148-2155Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper studies the possibility of building a Modular Multilevel Converter (M2C) using Silicon Carbide (SiC) switches. The main focus is on a theoretical investigation of the conduction losses of such a converter and a comparison to a corresponding converter with silicon insulated gate bipolar transistors. Both SiC BJTs and JFETs are considered and compared in order to choose the most suitable technology. One of the sub-modules of a down-scaled 10 kVA prototype M2C is replaced with a sub-module with SiC JFETs without anti-parallel diodes. It is shown that diode-less operation is possible with the JFETs conducting in the negative direction, leaving the possibility to use the body diode during the switching transients. Experimental waveforms for the SiC sub-module verify the feasibility during normal steady-state operation. The loss estimation shows that a 300 MW M2C for high-voltage direct current transmission would potentially have an efficiency of approximately 99,8 % if equipped with future 3.3 kV 1.2 kA SiC JFETs.

  • 21.
    Peftitsis, Dimosthenis
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Tolstoy, Georg
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Antonopoulos, Antonios
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Lim, Jang-Kwon
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Bakowski, Mietek
    Acreo AB.
    Ängquist, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    High-Power Modular Multilevel Converters With SiC JFETs2012Inngår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 27, nr 1, s. 28-36Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper studies the possibility of building a modular multilevel converter (M2C) using silicon carbide (SiC) switches. The main focus is on a theoretical investigation of the conduction losses of such a converter and a comparison to a corresponding converter with silicon-insulated gate bipolar transistors. Both SiC BJTs and JFETs are considered and compared in order to choose the most suitable technology. One of the submodules of a down-scaled 3 kVA prototype M2C is replaced with a submodule with SiC JFETs without antiparallel diodes. It is shown that the diode-less operation is possible with the JFETs conducting in the negative direction, leaving the possibility to use the body diode during the switching transients. Experimental waveforms for the SiC submodule verify the feasibility during normal steady-state operation. The loss estimation shows that a 300 MW M2C for high-voltage direct current transmission would potentially have an efficiency of approximately 99.8% if equipped with future 3.3 kV 1.2 kA SiC JFETs.

  • 22.
    Rabkowski, Jacek
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Mariusz, Zdanowski
    Warsaw Institute of Technology.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    A Simple High-Performance Low-Loss Current-Source Driver for SiC Bipolar Transistors2012Inngår i: 7th International Power Electronics and Motion Control Conference (IPEMC), 2012, IEEE conference proceedings, 2012, s. 222-228Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper proposes a novel topology of a simple base drive unit for silicon carbide bipolar junction transistors (BJTs) based on the current-source principle. Energy stored in a small, air-cored inductor is employed to generate a current peak forcing the BJT to turn-on (10–20ns) very rapidly. The driver enables very high switching performance and very low switching losses of the driven BJT. Both the current source and the unit delivering the steady-state current to the base are supplied from the same low-voltage source in order to limit power consumption. Operation principles as well as selected design issues are discussed in the paper and illustrated by experiments. The 1200V/6A SiC BJT driven by the proposed circuit shows a very fast switching speed.

  • 23.
    Rabkowski, Jacek
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Bakowski, Mietek
    Acreo.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Evaluation of the drive circuit for a dual gate trench SiC JFET2013Inngår i: SILICON CARBIDE AND RELATED MATERIALS 2012, 2013, s. 946-949Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper discusses the switching performance of the dual gate trench SiC JFET. In applications such as dc/dc converters, when fast switching is expected the standard totem-pole driver is not sufficient. The reason for this is that both the internal resistance and the parasitic capacitances of this device are significantly higher than for other designs. Instead, the gate driver with a dynamic current source is proposed in this paper to speed-up the switching process. Performed double-pulse measurements show improved dynamic performance of the tested DGTJFET with the new driver.

  • 24.
    Rabkowski, Jacek
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Mariusz, Zdanowski
    Warsaw Institute of Technology.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    A 6kW, 200kHz boost converter with parallel-connected SiC bipolar transistors2013Inngår i: 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference And Exposition (APEC 2013), IEEE Press, 2013, s. 1991-1998Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper describes issues related to design,construction and experimental verification of a 6 kW, 200 kHzboost converter (300 V/600 V) built with four parallel-connectedSiC bipolar transistors. The main focus is on parallel-connectionof the SiC BJTs: crucial device parameters and influence of theparasitics are discussed. A special solution for the base-driveunit, based on the dual-source driver concept, is also presentedin this paper. Experimental verification of the boost converterwith special attention to power loss measurement and thermalperformance of the parallel-connected transistors is also shown.The peak efficiency measured at nominal conditions wasapproximately 98.5% where the base-drive unit causes around 10% of the total losses.

  • 25.
    Rabkowski, Jacek
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Design Steps Toward a 40-kVA SiC JFET Inverter With Natural-Convection Cooling and an Efficiency Exceeding 99.5%2013Inngår i: IEEE transactions on industry applications, ISSN 0093-9994, E-ISSN 1939-9367, Vol. 49, nr 4, s. 1589-1598Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes the concept, design, construction, and experimental investigation of a 40-kVA inverter with silicon carbide junction field-effect transistors (JFETs). The inverter was designed to reach an efficiency exceeding 99.5%. The size of the heat sink is significantly reduced in comparison to silicon insulated-gate bipolar transistor designs, and the high efficiency makes it possible to use free-convection cooling. This could potentially increase reliability compared with solutions with fans. A very low conduction loss has been achieved by parallel connecting ten 85-m Omega normally-ON JFETs in each switch position. A special gate-drive solution was applied, forcing the transistors to switch very fast (approximately 10 kV/mu s), resulting in very low switching losses. As output power is almost equal to input power, special effort was done to precisely determine the amount of semiconductor power losses via comparative thermal measurements. A detailed analysis of the measurements shows that the efficiency of the inverter is close to 99.7% at 40 kVA.

  • 26.
    Rabkowski, Jacek
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Design steps towards a 40-kVA SiC inverter with an efficiency exceeding 99.5%2012Inngår i: Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC, IEEE , 2012, s. 1536-1543Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper describes the concept, the design, the construction, and experimental investigation of a 40 kVA inverter with Silicon Carbide Junction Field Effect Transistors. The inverter was designed to have an efficiency exceeding 99.5%. Due to the low losses free convection cooling could be used. Since no fans are used the reliability can be increased compared to solutions with fans. A very low conduction loss has been achieved by parallel connecting ten 85 mΩ normally-on JFETs in each switch position. A special gate-drive solution was applied forcing the transistors to switch very fast (approx. 20 kV/μs) resulting in very low switching losses. As the output power is almost equal to the input power a special effort was done to precisely determine the amount of semiconductor power losses via comparative thermal measurements. A detailed analysis of the measurements shows that the efficiency of the inverter is approximately 99.7% at 40 kVA.

  • 27.
    Rabkowski, Jacek
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Parallel-Operation of Discrete SiC BJTs in a 6-kW/250-kHz DC/DC Boost Converter2014Inngår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 29, nr 5, s. 2482-2491Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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 successful parallel-operation of the discrete BJTs. All considerations are experimentally illustrated by a 6-kW, 250-kHz boost converter (300 V/600 V). A special solution for the base-drive unit, based on the dual-source driver concept, is also shown in this paper. The performance of this driver and the current sharing of the BJTs are both presented. The power losses and thermal performance of the parallel-connected transistors have been determined experimentally for different powers and switching frequencies. An efficiency of 98.23% (+/- 0.02%) was measured using a calorimetric setup, while the maximum temperature difference among the four devices is 12 degrees C.

  • 28.
    Rabkowski, Jacek
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling. Warsaw University of Technology, Poland .
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Recent Advances in Power Semiconductor Technology2014Inngår i: Power Electronics for Renewable Energy Systems, Transportation and Industrial Applications, Wiley-Blackwell, 2014, s. 69-106Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    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 various SiC power switches along with experimental results of their switching performance are presented in details. Moreover, a section on applications of SiC power devices is also included, where the three design directions (high-efficiency, high switching frequency and high-temperature) that might be followed using SiC technology are shown. Last but not least, a short overview of Gallium Nitride transistors is presented in the last section of this chapter.

  • 29.
    Rabkowski, Jacek
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Silicon Carbide Power Transistors: A New Era in Power Electronics Is Initiated2012Inngår i: IEEE Industrial Electronics Magazine, ISSN 1932-4529, E-ISSN 1941-0115, Vol. 6, nr 2, s. 17-26Artikkel i tidsskrift (Fagfellevurdert)
  • 30.
    Rabkowski, Jacek
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Tolstoy, Georg
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Low-Loss High-Performance Base-Drive Unit for SiC BJTs2012Inngår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 27, nr 5, s. 2633-2643Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Driving a silicon carbide bipolar junction transistor is not a trivial issue, if low drive power consumption and short-switching times are desired. A dual-source base-drive unit with a speed-up capacitor consisting of a low-and a high-voltage source is, therefore, proposed in this paper. As a significant base current is required during the conduction state, the driver power consumption is higher than for other semiconductor switches. In the presented solution, the steady-state base current is provided by a low-voltage source and is optimized for lowpower losses. On the contrary, a second source with a higher voltage and speed-up capacitor is used in order to improve the switching performance of the device. The proposed driver has experimentally been compared to other standard driver solutions by using a double-pulse circuit and a 2-kW dc/dc boost converter. Switching times of 20 ns at turn-ON and 35 ns at turn-OFF were recorded. Finally, the efficiency of the converter was determined experimentally at various switching frequencies. From power loss measurements at 100-kHz switching frequency using the proposed driver in a 2-kW dc/dc boost converter, it was found that the efficiency was approximately 99.0%. In the same operating point, the driver power consumption was only 0.08% of the rated power.

  • 31.
    Ranstad, Per
    et al.
    Alstom Power.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Linner, Jörgen
    Alstom Power.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    An Experimental Evaluation of SiC Switches in Soft-Switching Converters2014Inngår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 29, nr 5, s. 2527-2538Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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 conduction losses but also other loss components of the IGBTs. In the present paper, therefore, several types of SiC transistors are compared to a state-of-the-art 1200-V Si IGBT. First, the conduction losses with sinusoidal current at a fixed amplitude (150 A) are investigated at different frequencies up to 200 kHz. It was found that the SiC transistors showed no signs of dynamic conduction losses in the studied frequency range. Second, the SiC transistors were compared to the Si IGBT in a realistic soft-switching converter test system. Using a calorimetric approach, it was found that all SiC transistors showed loss reductions of more than 50%. In some cases loss reductions of 65% were achieved even if the chip area of the SiC transistor was only 11% of that of the Si IGBT. It was concluded that by increasing the chip area to a third of the Si IGBT, the SiC vertical trench junction field-effect transistor could yield a loss reduction of approximately 90%. The reverse conduction capability of the channel of unipolar devices is also identified to be an important property for loss reductions. A majority of the new SiC devices are challenging from a gate/base driver point-of-view. This aspect must also be taken into consideration when making new designs of soft-switching converters using new SiC transistors.

  • 32.
    Sadik, Diane-Perle
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Colmenares, Juan
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Lim, Jang-Kwon
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Experimental investigations of static and transient current sharing of parallel-connected silicon carbide MOSFETs2013Inngår i: 2013 15th European Conference on Power Electronics and Applications, EPE 2013, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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-speed switching waveforms with small oscillations are presented. To conclude this analysis, a dc/dc boost converter using parallel-connected SiC MOSFETs is designed for stepping up a voltage from 50 V to 560 V. It has been found that at high frequencies, a mismatch in switching losses results in thermal unbalance between the devices.

  • 33.
    Sadik, Diane-Perle
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Colmenares, Juan
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Tolstoy, Georg
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Analysis of short-circuit conditions for silicon carbide power transistors and suggestions for protection2014Inngår i: 2014 16th European Conference on Power Electronics and Applications, EPE-ECCE Europe 2014, IEEE , 2014, s. 6910789-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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 suitable method for short-circuit detection without any comparator is demonstrated. A SiC JFET driver with an integrated short-circuit protection (SCP) is presented where a short-circuit detection is added to a conventional driver design in a simple way. Experimental tests of the SCP driver operating under short-circuit condition and under normal operation are performed successfully.

  • 34.
    Sadik, Diane-Perle
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Colmenares, Juan
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Tolstoy, Georg
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Bakowski, Mietek
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Short-Circuit Protection Circuits for Silicon Carbide Power Transistors2016Inngår i: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, ISSN 0278-0046, Vol. 63, nr 4, s. 1995-2004, artikkel-id ITIEDArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An experimental analysis of the behavior under short-circuit conditions of three different siliconcarbide (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 the die during a short-circuit event, for the SiC MOSFET. It was found that, for reliability reasons, the short-circuit time should be limited to values well below Si IGBT tolerances. Guidelines toward a rugged design for short-circuit protection (SCP) are presented with an emphasis on improving the reliability and availability of the overall system. A SiC device driver with an integrated SCP is presented for each device-type, respectively, where a shortcircuit detection is added to a conventional driver design in a simple way. The SCP driver was experimentally evaluated with a detection time of 180 ns. For all devices, short-circuit times well below 1 µs were achieved.

  • 35. Schöner, A.
    et al.
    Bakowski, M.
    Malhan, R. K.
    Takeuchi, Y.
    Sugiyama, N.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Ranstad, P.
    Nee, H. P.
    Fabrication of a SiC double gate vertical channel jfet and it's application in power electronics2012Inngår i: Gallium nitride and silicon carbide power technologies 2, Electrochemical Society, 2012, nr 3, s. 45-52Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The fabrication process of an innovative epitaxial trench JFET with vertical channel and double gate control is reviewed. Due to the excellent doping and thickness control of the epitaxial regrowth techniques, the sub-micron channel can be tailored for normally-on and -off operation. Due to the vertical channel design the epitaxial trench JFETs have narrow cell pitch for high-density power integration and high saturation current capabilities. The excellent performance of these fabricated and packaged JFET devices is demonstrated with on-wafer measurements and power switching tests. High current conduction tests are performed at room temperature and elevated temperatures of 125°C with switching frequencies of 30 kHz and 200 kHz.

  • 36.
    Tolstoy, Georg
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik.
    Lim, Jang-Kwon
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik.
    Bakowski, Mietek
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik.
    Circuit Modeling of Vertical Buried-Grid SiC JFETs2010Inngår i: SILICON CARBIDE AND RELATED MATERIALS 2009, PTS 1 AND 2   / [ed] Bauer AJ; Friedrichs P; Krieger M; Pensl G; Rupp R; Seyller T, 2010, Vol. 645-648, s. 965-968Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The main problem when the conventional PSpice JFET model is used to simulate a vertical short-channel buried-grid JFET is caused by the constant values of Threshold Voltage (VTO) and Transconductance (BETA). This paper presents a new model for the vertical short-channel buried-grid 1200V JEET, where both VTO and BETA vary with respect to the Drain-Source voltage. Simulation data from Medici have been analyzed in order to extract the analytical equations for VTO and BETA. Also other PSpice parameters are extracted from these data. The proposed circuit model has been simulated in Matlab by optimizing the same algorithm that PSpice uses. A variety of results are shown and discussed in this paper.

  • 37.
    Tolstoy, Georg
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik.
    Performance tests of a 4, 1x4, 1mm(2) SiC LCVJFET for a DC/DC boost converter application2011Inngår i: SILICON CARBIDE AND RELATED MATERIALS 2010 / [ed] Monakhov EV; Hornos T; Svensson BG, 2011, Vol. 679-680, s. 722-725Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A 4.1x4.1mm(2), 100m Omega 1,2kV lateral channel vertical junction field effect transistor (LCVJFET) built in silicon carbide (SiC) from SiCED, to use as the active switch component in a high-temperature operation DC/DC-boost converter, has been investigated. The switching loss for room temperature (RT) and on-state resistance (Ron) for RT up to 170 degrees C is investigated. Since the SiC VJFET has a buried body diode it is also ideal to use instead of a switch and diode setup. The voltage drop over the body diode decreases slightly with a higher temperature. A short-circuit test has also been conducted, which shows a high ruggedness.

  • 38.
    Tolstoy, Georg
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Palmer, P. R.
    A discretized proportional base driver for Silicon Carbide Bipolar Junction Transistors2013Inngår i: 2013 IEEE ECCE Asia Downunder - 5th IEEE Annual International Energy Conversion Congress and Exhibition, IEEE ECCE Asia 2013, IEEE , 2013, s. 728-735Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Silicon Carbide Bipolar Junction Transistors 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 which will reduce, for the right application, the steady-state power consumption of the base driver. The operation of the proposed base driver has been verified experimentally, driving a 1200V/40A SiC BJT in a DC-DC boost converter. In order to determine the potential reduction of the power consumption of the base driver, a case with a dc-dc converter in an ideal electric vehicle driving the new European drive cycle has been investigated. It is found that the steady-state power consumption of the base driver can be reduced by approximately 63 %. The total reduction of the driver consumption is 2816 J during the drive cycle, which is slightly more than the total on-state losses for the SiC BJTs used in the converter.

  • 39.
    Tolstoy, Georg
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Peftitsis, Dimosthenis
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Rabkowski, Jacek
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Palmer, Patrick R.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    A Discretized Proportional Base Driver for Silicon Carbide Bipolar Junction Transistors2014Inngår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 29, nr 5, s. 2408-2417Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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 which will reduce, for the right application, the steady-state power consumption of the base driver. The operation of the proposed base driver has been verified experimentally, driving a 1200-V/40-A SiC BJT in a dc-dc boost converter. In order to determine the potential reduction of the power consumption of the base driver, a case with a dc-dc converter in an ideal electric vehicle driving the new European drive cycle has been investigated. It is found that the steady-state power consumption of the base driver can be reduced by approximately 60%. The total reduction of the driver consumption is 3459 J during the drive cycle, which is slightly more than the total on-state losses for the SiC BJTs used in the converter.

1 - 39 of 39
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