EPE Association: EPE 2014 - DS2d: Hard Soft Switching Techniques

EPE 2014 - DS2d: Hard Soft Switching Techniques
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2014 ECCE Europe - Conference > EPE 2014 - Topic 02: Power Converter Topologies and Design > EPE 2014 - DS2d: Hard Soft Switching Techniques

   [return to parent folder]

   A 80kW Isolated DC-DC Converter for Railway Applications
By Nico BAARS, Henk HUISMAN, Jorge DUARTE, Jaap VERSCHOOR [View]
[Download]

Abstract: This paper presents the design of a three phase dual active bridge (DAB) topology as high-power-density dc-dc converter for railway applications. The three-phase DAB is analyzed concerning the current intervals, the output power and soft-switching region, including the effect of zero-voltage switching (ZVS) capacitors. Furthermore, two methods are discussed, aiming to extend the soft-switching region, since no-load conditions in the entire operating range are required. A prototype design is made, in which optimal component values are calculated, to minimize losses. Finally, a prototype is built with the required specifications, resulting in an efficiency of 95.6\% at 80kW of output power.

   A NOVEL ZCS SINGLE PHASE MATRIX CONVERTER FOR TRACTION APPLICATIONS
By Veera Venkata Subrah BHAJANA, PAVEL DRABEK, JARA MARTIN, BEDNAR BEDRICH [View]
[Download]

Abstract: This paper proposed a new ZCS single phase ac-ac matrix converter for the traction applications. The proposed soft switching matrix converter is enhanced with an auxiliary resonant circuit in order to achieve the zero current switching for main bidirectional switches of the matrix converter. The main advantage of this proposed topology is soft switching of matrix converter to achieve switching loses limitation. This paper describes the operation of the proposed matrix converter, simulation analysis and experimental validation of the prototype for 50V-16.7Hz-100W-400Hz.

   An Analysis into Bridgeless Inverted Buck-Boost PFC with ZVS Capabilities
By Kennith LEONG, Annette MUETZE [View]
[Download]

Abstract: This paper proposes a buck type PFC which is based on a new bridgeless inverted buck-boost circuit.The circuit can achieve ZVS for the full range via triangular current mode (TCM) and unlikeconventional buck PFC, the circuit can operate for the entire cycle. The bridgeless topology has fewernumbers of components in the conduction path than any other bridgeless boost PFC circuits. The idealfull control is discussed and a simplified control is also proposed which has almost the same efficiencywith a simulated peak value of ~97.5\%. This circuit also exhibits an interesting property of higherefficiencies at low load conditions which could be of interest for SMPS for laptops and computers.

   An Analysis of Inverter Switching Loss Minimization Based On Discontinuous PWM for a Salient-pole PMSM
By Andreas ANDERSSON, Torbjörn THIRINGER [View]
[Download]

Abstract: This article presents the result of an inverter switching loss minimization technique based on discontinuous PWM patterns for a salient-pole PMSM with a two-level voltage source inverter for an automotive application. The suggested PWM patterns are evaluated using the resulting electromagnetic torque considering peak-to-peak ripple as well as the DC-current harmonic spectra. The study focuses on high rotational speeds, from 0.6-2.5 times the base speed;base considering both current and voltage limitations. The analysis focuses on electromagnetic torque characteristics evaluated at steady state operation. The results show that the electromagnetic torque ripple is increased by up to 73 \% and 78 \% whereas the inverter switching losses is decreased by up to -17 \% and -41 \% for the EUDC driving cycle using DPWM30 and DPWM60, respectively.

   An experimental analysis of how the dead-time of SiC BJT and SiC MOSFET impacts the losses in a high-frequency resonant converter.
By Georg TOLSTOY, Per RANSTAD, Juan COLMENARES, Dimosthenis PEFTITSIS, Florian GIEZENDANNER, Jacek RABKOWSKI, Hans-Peter NEE [View]
[Download]

Abstract: Active control of the dead-time in a SLR converter is in this paper shown to be of great importance. Theefficiency of the full-bridge will increase if the dead-time control is made in the right way. Differentcontrol algorithms are shown to work well for different power switches. For the SiC MOSFET and theSiC BJT the control algorithms are tested experimentally.

   Analysis and Design of Snubber Circuit for Z-source Inverter
By Shuai DONG, Qianfan ZHANG, Chaowei ZHOU, Shukang CHENG [View]
[Download]

Abstract: The Z-Source Inverter (ZSI) is a novel and attractive topology for an power electronic interface. Shoot-through states are utilized to boost the DC bus voltage, which also differentiates the working process of the snubber circuit from that of a Voltage Source Inverter (VSI). It was found that there would be a distortion in the DC link voltage of four traditional snubber circuits, and that this voltage would increase more than it would have without the snubber circuit. Compared with a VSI, larger energy losses would be generated in this situation due to the shoot-through state. This paper presents an improved RCD snubber circuit for ZSI applications, which resolves the problems of voltage distor-tion and large energy losses. These theoretical findings and design guidelines for snubber circuits with a ZSI were then verified by computer simulation and experiment.

   Analysis and Optimization of the Asymmetrical Half-Bridge PWM Converter
By Tobias HIEKE, Thomas DUERBAUM, Jens GOETTLE [View]
[Download]

Abstract: The paper presents a detailed analysis of the asymmetrical half-bridge PWM converter. Due to its advantageswith regard to efficiency, power density and cost the topology gains increasing attention. Recentpublications propose a rough but simple converter model which helps to understand the basic converterfunctioning. A comparison between measured and simulated waveforms, however, reveals its insufficiency.The simple model fails to predict important converter characteristics. The necessary modelrefinement considers the actual capacitance and inductance values instead of replacing these componentsby ideal voltage or current sources. Further, according to previous research, incorporation of parasiticcomponents is inevitable for the development of an optimal design. Thus, the paper identifies the mostimportant parameters and reveals their primary influence on efficiency. Finally, an optimization strategyis proposed.

   Comparison of Switching Losses of Matrix Converters for Commutation Methods
By Sirichai TAMMARUCKWATTANA, Chenxin YUE, Yumi IKEDA, Kazuhiro OHYAMA [View]
[Download]

Abstract: In this paper, the switching losses of matrix converters (MCs) using various commutation methods are calculated with MATLAB/Simulink. The commutation methods of 2-steps current commutation, 4-steps current commutation, 2-steps voltage commutation, 4-steps voltage commutation, and 3-steps voltage current commutation are treated. This paper compares their switching losses and discusses their differences.

   Coupled Interleaved Multicellular Parallel Converters operated under Switching Frequency Modulation
By Juan MON, David GONZALEZ, Cirylle GAUTIER, Denis LABROUSSE, François COSTA [View]
[Download]

Abstract: The Coupled Interleaved Multicellular Parallel (CIMP) topology is the subject of intense research because of its advantages in terms of systems integration, power density increase, low level of EMI emissions and dynamic performance. This paper evaluates the viability of application of switching frequency modulation techniques to CIMP topology.

   Design Issues of the High-Frequency Interleaved DC/DC Boost Converter with Silicon Carbide MOSFETs
By Mariusz ZDANOWSKI, Jacek RABKOWSKI, Roman BARLIK [View]
[Download]

Abstract: This paper discusses design issues of the high-frequency, four-leg interleaved DC/DC boost converter. The main aim of this design is to fit the 6kW/650V converter prototype within volume of 1 dm3 having at the same time efficiency above 98\%. Low switching energies of applied SiC MOSFETs and Schottky diodes offer operation of each leg at high switching frequency up to 130 kHz. Together with a phase-shift by 90° this leads to input/output current frequency multiplication over 0.5MHz. Such a high frequencies result in a significant reduction of the passive components, especially input inductors. The paper contains discussion of the converter operation and special solution the MOSFET gate drivers with CPLD logic. A design study regarding SiC semiconductors, heatsink, inductors is also provided. All issues are illustrated by simulation and experimental results.

   Effects of Leakage Inductances on Magnetically-Coupled Impedance-Source Networks
By Yam SIWAKOTI, Poh Chiang LOH, Frede BLAABJERG, Graham TOWN [View]
[Download]

Abstract: Coupled inductors have lately been used with impedance-source networks for keeping their shoot-through times short, while providing higher voltage boosts. The parameter that is critical to the operation of such impedance network based converter with coupled inductors is the leakage inductances. However, the role of leakage inductances and its effect on the converter performance is often overlooked. This paper analyzes the effects of leakage inductances and demonstrates experimentally how the presence of leakage inductances degrades the performance of the converter.

   Efficient Hard-Switching DC/DC Converters for Envelope-Tracking Applications
By Fabien LEROY, Olivier DEBLECKER, Fortunato DUALIBE, Christophe DELEPAUT, Nicolas LE GALLOU [View]
[Download]

Abstract: This paper presents two buck converters switching at 50 MHz and based on Gallium Nitride dice. Thefirst converter features a diode designed for power applications and demonstrates 87.9\% peakefficiency. The diode mounted on the second one is aimed at higher-frequency operation and bringsthis value up above 91\% in the same operating conditions. Loss contributions are evaluated, showingthe influence of the diode alone on the efficiency of such converters.

   Half-cycle Sampled Discrete Model of Series-Parallel Resonant Converter with Optimized Modulation
By JUNBING TAO, Zhiyu CAO, Norbert FRÖHLEKE, Joachim BOECKER [View]
[Download]

Abstract: Because of low switching losses and wide operation range, series-parallel resonant converter with optimized modulation is attractive. There are three major modeling methods for resonant converters, including approximation method, extended describing function method, and sampled-data method. Approximation method and extended describing function method are simple but relatively inaccurate on heavy load conditions. Sampled-data method requires many computation resources which limits the utilization in control algorithm. A low computational cost and relatively accurate model, half-cycle sampled discrete model is proposed in this contribution. The model describes the behavior of converters with slow-varying variable and assumes variables constant in every half cycle. The model is verified by circuit simulation and experiments.

   Influence of Component Tolerances onto Design and Losses of Resonant LLC Converters
By Thomas DUERBAUM, Jonathan BINDER, Christian OEDER, Markus BARWIG [View]
[Download]

Abstract: There exist several publications addressing and presenting an optimal design strategy for resonant LLC converters to end up with minimal ohmic losses. However, none of these papers takes unavoidable component tolerances into account. As a result, the specification cannot be met anymore for critical operation points. This paper proposes a new design strategy for resonant LLC converters, which incorporates these component tolerances. The resulting design provides minimal rms losses and guarantees the fulfillment of the converter specification under all circumstances at the same time.

   Investigation of 1.2 kV SiC MOSFETs for Hard- and Soft-Switching Converters
By Abdullah EIAL AWWAD, Paul BIRGEL, Sibylle DIECKERHOFF [View]
[Download]

Abstract: In this paper, current silicon carbide (SiC) MOSFETs from two different manufacturers are evaluated including static and dynamic characteristics for different gate resistances, different load currents and at various temperatures. These power semiconductors are operated continuously at a high switching frequency of 1MHz comparing a hard- and a soft-switching converter. A calorimetric power loss measurement method is realized in order to achieve a good measurement accuracy, and the results are compared to the electrical measurements.

   New Aspects on Analyzing ZVS Conditions for Converters Using Super-junction Si and Wide Bandgap SiC and GaN Power FETs
By Rais MIFTAKHUTDINOV [View]
[Download]

Abstract: Paper analyzes substantial Coss behavior differences of FETs using super-junction Si, SiC and GaN technologies versus traditional Si process and suggests new practical models for power losses optimization. These models applied to derive normalized ZVS conditions and boundaries for popular PWM ZVS topologies allowing efficiency optimization at wide operating conditions.

   New Design of High Switching Power Amplifier for Driving Piezoelectric Actuators in Aeronautic Applications
By Mouhanned BRAHIM [View]
[Download]

Abstract: Nowadays, piezoelectric actuators (PA) are used in fast power actuations and high power applications as requested in machine tools or helicopters flap applications. Regarding to the low power capability and high loss ratios of linear amplifiers, Switching Power Amplifiers (SA75X) is designed by Cedrat Technologies to drive piezoelectric actuators in such applications. The switching technique (up to 100 kHz) allows high current peaks required by impulse or by high frequency applications on large piezoelectric actuators (or actuators in parallel) and allows energy harvesting. Output voltage, current, and actuator position are monitored via controller board and using sensor feedbacks. Furthermore, the developed system (SA75X+actuators) can operate in open or closed loop system with an output signal frequency up to 1 kHz. The OEM version of the powerful switching amplifier (SA75D:20Amax) has a dimensions of 100x100x100mm, i.e. 1 litter, and a weight of 850g.The power ratio of this amplifier is thus of 1.5kVA/L and 1.75kVA/Kg. The output power capability, signal noise ratios, and control robustness of the SA75X justifies the proposed solution Theoretical, simulation, and experimental tests of the SA75D (20Amax) will be presented to improve the amplifier's performances.

   Novel Family of Quasi-Z-Source DC/DC Converters Derived from Current-Fed Push-Pull Converters
By Andrii CHUB, Oleksandr HUSEV, Dmitri VINNIKOV, Frede BLAABJERG [View]
[Download]

Abstract: This paper is devoted to the step-up quasi-Z-source dc/dc push-pull converter family. The topologiesin the family are derived from the isolated boost converter family by replacing input inductors with thequasi-Z-source network. Two new topologies are proposed, analyzed and compared. Theoreticalpredictions are verified by means of simulations.

   Optimized Pulse Width Modulation for Transformerless Active-NPC Inverters
By NIKOS ACHILLADELIS, FREDE BLAABJERG [View]
[Download]

Abstract: The transformerless DC/AC inverter topologies are employed in Photovoltaic systems in order toimprove the power conversion efficiency, power density and cost. The Active-Neutral Point Clamped(Active-NPC) transformerless inverters have the advantage of achieving better thermal balance amongtheir power semiconductors. In this paper, a new modulation technique is proposed for optimallycontrolling the power switches employed in transformerless Active-NPC inverters. The design resultsdemonstrate that compared to the existing PWM strategies, using the proposed method results in lowertotal power losses and significantly better distribution of the power losses among the semiconductorsof the Active-NPC inverter.

   SiC single switch resonant inverters performance dependence on induction load
By Carlos BERNAL, Javier AVELLANED, Javier LEON, Pilar MOLINA [View]
[Download]

Abstract: In this paper, a comparison between several induction loads operating in a One Switch Zero Voltage Switching (1SW-ZVS) resonant converter is presented. The aim is to determine the optimal load for induction cooking systems from the point of view of maximizing the performance of a given active device (Si IGBT or SiC JFET) in this resonant topology.

   Soft Switching of IGBTs in Lagging Lag of ZVT Phase Shift DC/DC Converter
By Sandra ZELJKOVIC, Tomas REITER, Dieter GERLING [View]
[Download]

Abstract: The additional effort to achieve zero voltage transition (ZVT) in the lagging leg of frequently used ZVT phase shift full bridge converter can be avoided by designing the converter with high speed trench fieldstop IGBTs. Thanks to their reduced turn-off but at the same time low turn-on losses, the lost of ZVT in the lagging leg is not anymore critical to converters efficiency. Moreover, it can be beneficial due to their improved conduction to switching loss ratio. Based on that conclusion, a simple method to maximize their efficiency by minimizing the resonant inductance is proposed.

   Steady-state Analysis of Zero-Voltage Transition Large Step-Down Buck Converter
By Veerachary MUMMADI [View]
[Download]

Abstract: A zero-voltage transition large step-down buck converter is proposed in this paper. It provides larger step-down voltage ratio together with soft transition to one of the switch during turn-ON process. Furthermore, it transfers power to load at reduced current ripple, which is smaller in comparison to the conventional buck converter source current ripple. A pseudo zero-voltage transition cell is introduced to achieve soft-switching feature during turn-ON transition to one of the switches. This cell not only results in ZVT performance to the main switch, but also gives zero-current transition features to all the diodes present in the converter. Various operating modes of the circuit are identified and then steady-state time-domain analysis is established. Necessary and sufficient conditions for ensuring soft-switching are derived. To demonstrate the effectiveness of the proposed zero-voltage transition converter, PSIM simulations are carried out and then verified through experiments. A 48 to 12 V, 50 kHz low power prototype is use for experimentation. Measured and theoretical predicted results are in close agreement with each other.

   THREE-LEVEL BOOST CONVERTERS. MODES, SUB-MODES AND ASYMMETRICAL REGIME OF OPERATION
By Semen SACHKOV, Valery MELESHIN, Sergey KHUKHTIKOV [View]
[Download]

Abstract: A growing need for more efficient generation, distribution and conversion energy intensivelydrives exploration of new power converters topologies. The paper compares key designparameters of multilevel and three-level boost converters based on fly capacitor and clampingdiodes. Main attention has been paid to three-level boost converter with clamping diodestructures along with features under operation in various modes and sub-modes in static anddynamics as well. A theoretical analysis has been confirmed by large number modeling andexperiments.

EPE 2014 - DS2d: Hard Soft Switching Techniques
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2014 ECCE Europe - Conference > EPE 2014 - Topic 02: Power Converter Topologies and Design > EPE 2014 - DS2d: Hard Soft Switching Techniques
	[return to parent folder]

	A 80kW Isolated DC-DC Converter for Railway Applications By Nico BAARS, Henk HUISMAN, Jorge DUARTE, Jaap VERSCHOOR	[View] [Download]
Abstract: This paper presents the design of a three phase dual active bridge (DAB) topology as high-power-density dc-dc converter for railway applications. The three-phase DAB is analyzed concerning the current intervals, the output power and soft-switching region, including the effect of zero-voltage switching (ZVS) capacitors. Furthermore, two methods are discussed, aiming to extend the soft-switching region, since no-load conditions in the entire operating range are required. A prototype design is made, in which optimal component values are calculated, to minimize losses. Finally, a prototype is built with the required specifications, resulting in an efficiency of 95.6\% at 80kW of output power.

	A NOVEL ZCS SINGLE PHASE MATRIX CONVERTER FOR TRACTION APPLICATIONS By Veera Venkata Subrah BHAJANA, PAVEL DRABEK, JARA MARTIN, BEDNAR BEDRICH	[View] [Download]
Abstract: This paper proposed a new ZCS single phase ac-ac matrix converter for the traction applications. The proposed soft switching matrix converter is enhanced with an auxiliary resonant circuit in order to achieve the zero current switching for main bidirectional switches of the matrix converter. The main advantage of this proposed topology is soft switching of matrix converter to achieve switching loses limitation. This paper describes the operation of the proposed matrix converter, simulation analysis and experimental validation of the prototype for 50V-16.7Hz-100W-400Hz.

	An Analysis into Bridgeless Inverted Buck-Boost PFC with ZVS Capabilities By Kennith LEONG, Annette MUETZE	[View] [Download]
Abstract: This paper proposes a buck type PFC which is based on a new bridgeless inverted buck-boost circuit.The circuit can achieve ZVS for the full range via triangular current mode (TCM) and unlikeconventional buck PFC, the circuit can operate for the entire cycle. The bridgeless topology has fewernumbers of components in the conduction path than any other bridgeless boost PFC circuits. The idealfull control is discussed and a simplified control is also proposed which has almost the same efficiencywith a simulated peak value of ~97.5\%. This circuit also exhibits an interesting property of higherefficiencies at low load conditions which could be of interest for SMPS for laptops and computers.

	An Analysis of Inverter Switching Loss Minimization Based On Discontinuous PWM for a Salient-pole PMSM By Andreas ANDERSSON, Torbjörn THIRINGER	[View] [Download]
Abstract: This article presents the result of an inverter switching loss minimization technique based on discontinuous PWM patterns for a salient-pole PMSM with a two-level voltage source inverter for an automotive application. The suggested PWM patterns are evaluated using the resulting electromagnetic torque considering peak-to-peak ripple as well as the DC-current harmonic spectra. The study focuses on high rotational speeds, from 0.6-2.5 times the base speed;base considering both current and voltage limitations. The analysis focuses on electromagnetic torque characteristics evaluated at steady state operation. The results show that the electromagnetic torque ripple is increased by up to 73 \% and 78 \% whereas the inverter switching losses is decreased by up to -17 \% and -41 \% for the EUDC driving cycle using DPWM30 and DPWM60, respectively.

	An experimental analysis of how the dead-time of SiC BJT and SiC MOSFET impacts the losses in a high-frequency resonant converter. By Georg TOLSTOY, Per RANSTAD, Juan COLMENARES, Dimosthenis PEFTITSIS, Florian GIEZENDANNER, Jacek RABKOWSKI, Hans-Peter NEE	[View] [Download]
Abstract: Active control of the dead-time in a SLR converter is in this paper shown to be of great importance. Theefficiency of the full-bridge will increase if the dead-time control is made in the right way. Differentcontrol algorithms are shown to work well for different power switches. For the SiC MOSFET and theSiC BJT the control algorithms are tested experimentally.

	Analysis and Design of Snubber Circuit for Z-source Inverter By Shuai DONG, Qianfan ZHANG, Chaowei ZHOU, Shukang CHENG	[View] [Download]
Abstract: The Z-Source Inverter (ZSI) is a novel and attractive topology for an power electronic interface. Shoot-through states are utilized to boost the DC bus voltage, which also differentiates the working process of the snubber circuit from that of a Voltage Source Inverter (VSI). It was found that there would be a distortion in the DC link voltage of four traditional snubber circuits, and that this voltage would increase more than it would have without the snubber circuit. Compared with a VSI, larger energy losses would be generated in this situation due to the shoot-through state. This paper presents an improved RCD snubber circuit for ZSI applications, which resolves the problems of voltage distor-tion and large energy losses. These theoretical findings and design guidelines for snubber circuits with a ZSI were then verified by computer simulation and experiment.

	Analysis and Optimization of the Asymmetrical Half-Bridge PWM Converter By Tobias HIEKE, Thomas DUERBAUM, Jens GOETTLE	[View] [Download]
Abstract: The paper presents a detailed analysis of the asymmetrical half-bridge PWM converter. Due to its advantageswith regard to efficiency, power density and cost the topology gains increasing attention. Recentpublications propose a rough but simple converter model which helps to understand the basic converterfunctioning. A comparison between measured and simulated waveforms, however, reveals its insufficiency.The simple model fails to predict important converter characteristics. The necessary modelrefinement considers the actual capacitance and inductance values instead of replacing these componentsby ideal voltage or current sources. Further, according to previous research, incorporation of parasiticcomponents is inevitable for the development of an optimal design. Thus, the paper identifies the mostimportant parameters and reveals their primary influence on efficiency. Finally, an optimization strategyis proposed.

	Comparison of Switching Losses of Matrix Converters for Commutation Methods By Sirichai TAMMARUCKWATTANA, Chenxin YUE, Yumi IKEDA, Kazuhiro OHYAMA	[View] [Download]
Abstract: In this paper, the switching losses of matrix converters (MCs) using various commutation methods are calculated with MATLAB/Simulink. The commutation methods of 2-steps current commutation, 4-steps current commutation, 2-steps voltage commutation, 4-steps voltage commutation, and 3-steps voltage current commutation are treated. This paper compares their switching losses and discusses their differences.

	Coupled Interleaved Multicellular Parallel Converters operated under Switching Frequency Modulation By Juan MON, David GONZALEZ, Cirylle GAUTIER, Denis LABROUSSE, François COSTA	[View] [Download]
Abstract: The Coupled Interleaved Multicellular Parallel (CIMP) topology is the subject of intense research because of its advantages in terms of systems integration, power density increase, low level of EMI emissions and dynamic performance. This paper evaluates the viability of application of switching frequency modulation techniques to CIMP topology.

	Design Issues of the High-Frequency Interleaved DC/DC Boost Converter with Silicon Carbide MOSFETs By Mariusz ZDANOWSKI, Jacek RABKOWSKI, Roman BARLIK	[View] [Download]
Abstract: This paper discusses design issues of the high-frequency, four-leg interleaved DC/DC boost converter. The main aim of this design is to fit the 6kW/650V converter prototype within volume of 1 dm3 having at the same time efficiency above 98\%. Low switching energies of applied SiC MOSFETs and Schottky diodes offer operation of each leg at high switching frequency up to 130 kHz. Together with a phase-shift by 90° this leads to input/output current frequency multiplication over 0.5MHz. Such a high frequencies result in a significant reduction of the passive components, especially input inductors. The paper contains discussion of the converter operation and special solution the MOSFET gate drivers with CPLD logic. A design study regarding SiC semiconductors, heatsink, inductors is also provided. All issues are illustrated by simulation and experimental results.

	Effects of Leakage Inductances on Magnetically-Coupled Impedance-Source Networks By Yam SIWAKOTI, Poh Chiang LOH, Frede BLAABJERG, Graham TOWN	[View] [Download]
Abstract: Coupled inductors have lately been used with impedance-source networks for keeping their shoot-through times short, while providing higher voltage boosts. The parameter that is critical to the operation of such impedance network based converter with coupled inductors is the leakage inductances. However, the role of leakage inductances and its effect on the converter performance is often overlooked. This paper analyzes the effects of leakage inductances and demonstrates experimentally how the presence of leakage inductances degrades the performance of the converter.

	Efficient Hard-Switching DC/DC Converters for Envelope-Tracking Applications By Fabien LEROY, Olivier DEBLECKER, Fortunato DUALIBE, Christophe DELEPAUT, Nicolas LE GALLOU	[View] [Download]
Abstract: This paper presents two buck converters switching at 50 MHz and based on Gallium Nitride dice. Thefirst converter features a diode designed for power applications and demonstrates 87.9\% peakefficiency. The diode mounted on the second one is aimed at higher-frequency operation and bringsthis value up above 91\% in the same operating conditions. Loss contributions are evaluated, showingthe influence of the diode alone on the efficiency of such converters.

	Half-cycle Sampled Discrete Model of Series-Parallel Resonant Converter with Optimized Modulation By JUNBING TAO, Zhiyu CAO, Norbert FRÖHLEKE, Joachim BOECKER	[View] [Download]
Abstract: Because of low switching losses and wide operation range, series-parallel resonant converter with optimized modulation is attractive. There are three major modeling methods for resonant converters, including approximation method, extended describing function method, and sampled-data method. Approximation method and extended describing function method are simple but relatively inaccurate on heavy load conditions. Sampled-data method requires many computation resources which limits the utilization in control algorithm. A low computational cost and relatively accurate model, half-cycle sampled discrete model is proposed in this contribution. The model describes the behavior of converters with slow-varying variable and assumes variables constant in every half cycle. The model is verified by circuit simulation and experiments.

	Influence of Component Tolerances onto Design and Losses of Resonant LLC Converters By Thomas DUERBAUM, Jonathan BINDER, Christian OEDER, Markus BARWIG	[View] [Download]
Abstract: There exist several publications addressing and presenting an optimal design strategy for resonant LLC converters to end up with minimal ohmic losses. However, none of these papers takes unavoidable component tolerances into account. As a result, the specification cannot be met anymore for critical operation points. This paper proposes a new design strategy for resonant LLC converters, which incorporates these component tolerances. The resulting design provides minimal rms losses and guarantees the fulfillment of the converter specification under all circumstances at the same time.

	Investigation of 1.2 kV SiC MOSFETs for Hard- and Soft-Switching Converters By Abdullah EIAL AWWAD, Paul BIRGEL, Sibylle DIECKERHOFF	[View] [Download]
Abstract: In this paper, current silicon carbide (SiC) MOSFETs from two different manufacturers are evaluated including static and dynamic characteristics for different gate resistances, different load currents and at various temperatures. These power semiconductors are operated continuously at a high switching frequency of 1MHz comparing a hard- and a soft-switching converter. A calorimetric power loss measurement method is realized in order to achieve a good measurement accuracy, and the results are compared to the electrical measurements.

	New Aspects on Analyzing ZVS Conditions for Converters Using Super-junction Si and Wide Bandgap SiC and GaN Power FETs By Rais MIFTAKHUTDINOV	[View] [Download]
Abstract: Paper analyzes substantial Coss behavior differences of FETs using super-junction Si, SiC and GaN technologies versus traditional Si process and suggests new practical models for power losses optimization. These models applied to derive normalized ZVS conditions and boundaries for popular PWM ZVS topologies allowing efficiency optimization at wide operating conditions.

	New Design of High Switching Power Amplifier for Driving Piezoelectric Actuators in Aeronautic Applications By Mouhanned BRAHIM	[View] [Download]
Abstract: Nowadays, piezoelectric actuators (PA) are used in fast power actuations and high power applications as requested in machine tools or helicopters flap applications. Regarding to the low power capability and high loss ratios of linear amplifiers, Switching Power Amplifiers (SA75X) is designed by Cedrat Technologies to drive piezoelectric actuators in such applications. The switching technique (up to 100 kHz) allows high current peaks required by impulse or by high frequency applications on large piezoelectric actuators (or actuators in parallel) and allows energy harvesting. Output voltage, current, and actuator position are monitored via controller board and using sensor feedbacks. Furthermore, the developed system (SA75X+actuators) can operate in open or closed loop system with an output signal frequency up to 1 kHz. The OEM version of the powerful switching amplifier (SA75D:20Amax) has a dimensions of 100x100x100mm, i.e. 1 litter, and a weight of 850g.The power ratio of this amplifier is thus of 1.5kVA/L and 1.75kVA/Kg. The output power capability, signal noise ratios, and control robustness of the SA75X justifies the proposed solution Theoretical, simulation, and experimental tests of the SA75D (20Amax) will be presented to improve the amplifier's performances.

	Novel Family of Quasi-Z-Source DC/DC Converters Derived from Current-Fed Push-Pull Converters By Andrii CHUB, Oleksandr HUSEV, Dmitri VINNIKOV, Frede BLAABJERG	[View] [Download]
Abstract: This paper is devoted to the step-up quasi-Z-source dc/dc push-pull converter family. The topologiesin the family are derived from the isolated boost converter family by replacing input inductors with thequasi-Z-source network. Two new topologies are proposed, analyzed and compared. Theoreticalpredictions are verified by means of simulations.

	Optimized Pulse Width Modulation for Transformerless Active-NPC Inverters By NIKOS ACHILLADELIS, FREDE BLAABJERG	[View] [Download]
Abstract: The transformerless DC/AC inverter topologies are employed in Photovoltaic systems in order toimprove the power conversion efficiency, power density and cost. The Active-Neutral Point Clamped(Active-NPC) transformerless inverters have the advantage of achieving better thermal balance amongtheir power semiconductors. In this paper, a new modulation technique is proposed for optimallycontrolling the power switches employed in transformerless Active-NPC inverters. The design resultsdemonstrate that compared to the existing PWM strategies, using the proposed method results in lowertotal power losses and significantly better distribution of the power losses among the semiconductorsof the Active-NPC inverter.

	SiC single switch resonant inverters performance dependence on induction load By Carlos BERNAL, Javier AVELLANED, Javier LEON, Pilar MOLINA	[View] [Download]
Abstract: In this paper, a comparison between several induction loads operating in a One Switch Zero Voltage Switching (1SW-ZVS) resonant converter is presented. The aim is to determine the optimal load for induction cooking systems from the point of view of maximizing the performance of a given active device (Si IGBT or SiC JFET) in this resonant topology.

	Soft Switching of IGBTs in Lagging Lag of ZVT Phase Shift DC/DC Converter By Sandra ZELJKOVIC, Tomas REITER, Dieter GERLING	[View] [Download]
Abstract: The additional effort to achieve zero voltage transition (ZVT) in the lagging leg of frequently used ZVT phase shift full bridge converter can be avoided by designing the converter with high speed trench fieldstop IGBTs. Thanks to their reduced turn-off but at the same time low turn-on losses, the lost of ZVT in the lagging leg is not anymore critical to converters efficiency. Moreover, it can be beneficial due to their improved conduction to switching loss ratio. Based on that conclusion, a simple method to maximize their efficiency by minimizing the resonant inductance is proposed.

	Steady-state Analysis of Zero-Voltage Transition Large Step-Down Buck Converter By Veerachary MUMMADI	[View] [Download]
Abstract: A zero-voltage transition large step-down buck converter is proposed in this paper. It provides larger step-down voltage ratio together with soft transition to one of the switch during turn-ON process. Furthermore, it transfers power to load at reduced current ripple, which is smaller in comparison to the conventional buck converter source current ripple. A pseudo zero-voltage transition cell is introduced to achieve soft-switching feature during turn-ON transition to one of the switches. This cell not only results in ZVT performance to the main switch, but also gives zero-current transition features to all the diodes present in the converter. Various operating modes of the circuit are identified and then steady-state time-domain analysis is established. Necessary and sufficient conditions for ensuring soft-switching are derived. To demonstrate the effectiveness of the proposed zero-voltage transition converter, PSIM simulations are carried out and then verified through experiments. A 48 to 12 V, 50 kHz low power prototype is use for experimentation. Measured and theoretical predicted results are in close agreement with each other.

	THREE-LEVEL BOOST CONVERTERS. MODES, SUB-MODES AND ASYMMETRICAL REGIME OF OPERATION By Semen SACHKOV, Valery MELESHIN, Sergey KHUKHTIKOV	[View] [Download]
Abstract: A growing need for more efficient generation, distribution and conversion energy intensivelydrives exploration of new power converters topologies. The paper compares key designparameters of multilevel and three-level boost converters based on fly capacitor and clampingdiodes. Main attention has been paid to three-level boost converter with clamping diodestructures along with features under operation in various modes and sub-modes in static anddynamics as well. A theoretical analysis has been confirmed by large number modeling andexperiments.