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EPE 2021 - Dialogue session - Power Converters Topologies
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2021 ECCE Europe - Conference > EPE 2021 - Topic 02: Power Converter Topologies and Design > EPE 2021 - Dialogue session - Power Converters Topologies
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	3.3kV-Silicon-Silicon Carbide-Topology-Hybrid-Switch for High Power Resonant ZVS Inverters - Optimisation of the Power Losses   By Michael MEISSNER	[View]   [Download]
Abstract: In order to investigate the capabilities of a hybrid switch setup consisting of two different semiconductormaterials, namely silicon (Si) and silicon carbide (SiC), two different technologies (MOSFET and IGBT) and further a combination of two topologies (NPC and half bridge) within a resonant converter a series of measurements have been conducted. In this context, especially the impact of resonant frequency as well as delay and dead time intervals will be presented by this contribution.
	A Buck-Boost Embedded Multilevel Inverter with Double Voltage Gain   By Theodoros MOUSELINOS	[View]   [Download]
Abstract: This work focuses on a Multilevel Inverter topology with an embedded voltage boosting feature. The inverter under investigation, integrates a DC/DC Buck-Boost converter to double the input voltage and the cascaded extension of the topology is presented. The power processing characteristics of the topology are evaluated to prove that the integrated DC/DC converter processes only a fraction of the total supplied active power. Also, the passive component selection of the topology is thoroughly analyzed under the DCM operation of the embedded DC/DC converter. A 1kVA prototype is implemented to study via experimental probing the performance and the efficiency of the topology.
	A Family of Quasi-Decoupled Three-Port Isolated DC-DC Converters Utilizing Asymmetric Impedances   By Muhammad YAQOOB	[View]   [Download]
Abstract: A quasi-decoupled family of the three-port DC-DC converters for the applications requiring multipleDC power sources is proposed. The proposed topologies employ a two-level quasi-decoupling approach that combines circuit and control levels decoupling to provide enhanced freedom for manipulation of the control parameters to achieve efficient power conversion among ports. The circuit-level quasi-decoupling is achieved by a choice and configuration of the asymmetric impedances, however, control-level quasi-decoupling is realized by appropriately selecting and varying the available control parameters. The proposed topologies and control method results in a simplified power-flow control with increased freedom to vary control parameters for achieving minimum reactive current to reduce conduction loss and soft-switching to reduce switching loss. To validate the proposed quasi-decoupled topologies, a three-port DC-DC converter based on a dual-active-bridge (DAB) converter with asymmetrical impedances and optimized selection of control parameters is built for electric vehicle (EV) on-board-charger (OBC) applications.
	A new topology of resonant inverter including a piezoelectric component   By Vincent MASSAVIE	[View]   [Download]
Abstract: This document introduces a new resonant inverter topology based on the F2 inverter. This new topology uses multiple resonance to pass fundamental and third harmonic at the switch terminals by filtering second harmonic with a piezoelectric component. This helps to reduce the voltage stress on the switch. Adding a piezoelectric resonator allows a better frequency stability and a better performance than a classic LC circuit. The structure and the design of the topology are described. Experimental results demonstrating the feasibility of the topology and a comparison with simulation results are done. The prototype works at 1.4MHz for an input voltage of 20V, an AC output voltage of 20V and an output power of 15W.
	A New Two-Stage Single-Phase Transformerless Inverter Topology with a Novel DC/DC High Gain Boost Converter and a Three-Level Neutral-Point-Clamped Inverter for   By Babak ROOHOLAHI	[View]   [Download]
Abstract: A new two-stage grid-connected inverter is presented in this paper. The proposed single-phase transformerless inverter topology consists of a novel front-end interleaved switched-capacitor boost converter and a half-bridge neutral-point-clamped inverter (HB NPC). The proposed topology is designed to be applied in photovoltaic (PV) conversion systems. The new two-stage compact inverter structure with a high gain interleaved boost converter in the first stage boosts the DC input voltage and provides the maximum power point tracking of the PV panels. In the second stage, a new arrangement of the HB NPC inverter is employed to implement the common ground technique, eliminate the leakage current and provide the DC/AC integration of the system to the grid. In comparison with conventional topologies, the presented inverter has two-stage operation with a compact single-stage design. As a result, the presented topology has several advantages, such as a reduction in the number of power semiconductors, higher efficiency, eliminated leakage current, and higher boosting gain. The design procedure, operating principles, comparison assessment, and simulation results for a 4600 W prototype are presented to verify the effectiveness of the proposed inverter. MATLAB/Simulink and PLECS Blockset are the simulation programs used to validate the performance of the presented topology.
	Active Filter Damping for a GaN-Based Three Phase Power Stage with Continuous Output Voltage   By Sabrina ULMER	[View]   [Download]
Abstract: This contribution presents a three-phase power stage for motor control with continuous output voltagesusing wide bandgap semiconductors and an asynchronous delta-sigma based switching signal generation. The focus of the paper is on an active damping approach for the LC output filter based on inductor current feedback.
	Adaptive Zero-Sequence Voltage Injection for Modular Solid-State Transformer to Compensate for Asymmetrical Fault Conditions   By Roland UNRUH	[View]   [Download]
Abstract: Modular solid-state transformers (SSTs) are a promising technology in converting power from a 10kVthree-phase medium voltage to a lower DC-voltage in the range of 100...400V to provide pure DC power to applications such as electrolyzers for hydrogen generation, data centers with a DC power distribution and DC micro grids. Modular SSTs which can be interpreted as modular multilevel converters with an isolated DC-DC output stage per module, are designed with redundant modules to increase reliability. Usually, each of the three arms operates independently, and therefore, only a fixed number of faulty modules can be compensated in each arm, even if all modules are operational in the remaining two arms. With the proposed zero-sequence voltage injection, up to 100\% more faulty modules can be compensated in an arm by employing the same hardware. In addition, module power imbalances are nearly eliminated by utilizing a fundamental frequency zero-sequence voltage. A dominant 3rd harmonic zero-sequence voltage injection in combination with the 5th, 7th and several higher order harmonics with adaptive (small) amplitudes minimize the required arm voltages at steady-state. For nominal operation or symmetrical faults, the proposed technique is equivalent to the well known Min-Max voltage injection, which already reduces the peak arm voltage by 13.4\% compared to a constant star point potential. A statistical analysis proves, that the expected number of tolerable faulty modules of the 1MW SST increases by 12\% without the need for additional hardware.
	Analysis and Implementation of a Novel four-step Commutation Method for Direct Matrix Converters based on FPGA and DSP   By Jun XIE	[View]   [Download]
Abstract: This paper presents a novel current-controlled four-step commutation method for robust and safe operation of direct matrix converters (DMC) by dynamically adjusting the most critical commutation time according to amplitude of the output load current, which is an optimization for the overall necessary commutation time. Meanwhile, this method also helps to ensure the desired switching sequence to be implemented correctly. The principle of proposed strategy is explained in detail and a formula of setting the most critical commutation time is given. Simulation results are used to verify this proposed strategy. A low voltage laboratory platform consisting of a DMC and a brushless motor (BLDC) is implemented and controlled using a hybrid hardware concept based on a field-programmable gate array (FPGA) and a digital signal processor (DSP). Experimental studies on the laboratory prototype confirm the feasibility and effectiveness of the proposed method.
	Aspects of Filter Design and Isolation for Medium Voltage Drives Inverters with 6.5 kV SiC-MOSFETs and high Switching Frequency   By Dirk KRANZER	[View]   [Download]
Abstract: In this paper different aspects of filter design and isolation are discussed for the application of 6.5 kVSiC-MOSFETs to achieve higher power density while coping with the challenge of a high dv/dt toachieve switching frequencies which are up to 20 times higher than with Si-IGBTs.
	Bidirectional MHz-switching Multi-cell Converter for Low-voltage Bufferless Power Electronic Transformer (BLPET)   By Yusuke HAYASHI	[View]   [Download]
Abstract: Multicellular buffer-less power electronic transformer (BLPET) has been newly proposed to develop high power density industrial control transformers. The bidirectional and unregulated isolated dc-dc converters of over 1 MHz switching frequency are utilized for the cell converters, and the cell converters are stacked based on the ISOP (Input Series Output Parallel) -IPOS (Input Parallel Output Series) connection topology to realize higher voltage multi-cell PET operated at over 1 MHz switching frequency. The high frequency multi-cell PET enables to reverse the power flow derived from the reactive load instantaneously without the large energy buffer capacitors. An ac 100 V-ac 100 V, 1.35 kVA multi-cell BLPET has been fabricated, and the successful circuit operation under the inductive load condition with the power factor of 0.7 has been verified experimentally. The proposed approach has also demonstrated the potential to realize the volume reduction of 1/14 and the weight saving of 1/40 compared with the commercially available ac 100 V line frequency transformer.
	Characterization of Enhancement-Mode Asymmetrical GaN Transistor Half Bridge in High frequency Operation   By Wei-Ren LIN	[View]   [Download]
Abstract: In this paper, an enhancement-mode asymmetrical GaN transistor half-bridge fabricated on 200mm GaN-on-SOI substrate is analysed, and the performance at 1 MHz and 2MHz switching frequency is evaluated. Comparisons with symmetrical commercial GaN transistor half-bridge under the same operation are made. The benefits of optimized selections of the high-side and low-side devices are discussed. By choosing an optimized high-side device, a higher slew rate with an acceptable overshoot voltage is achieved.
	Comparison of magnetic coupling topologies for interleaved multilevel inverters   By Rita MATTAR	[View]   [Download]
Abstract: This paper presents a study and comparison in terms of magnetic circuit sizing for two magnetic coupling topologies for interleaved multilevel inverters: the cyclic cascade and the secondary loop. This comparison includes modeling of both topologies and simulation analysis of the sizing of each of them. The interleaved multilevel inverter is then simulated with the sized magnetic components for the system operating point for both topologies. Then, a secondary loop improvement study is developed and simulated to minimize the sizing current for this topology. Finally, an experimental test bench is presented to test and analyze the experimental results for both topologies for a measurement power point of 10 kW.
	Cryo-MMC: a Modular Multilevel Converter with Superconductor Arm Coils   By Rafael COELHO-MEDEIROS	[View]   [Download]
Abstract: In this article, we study the integration of high-temperature superconducting arm coils in a modularmultilevel converter (Cryo-MMC). With this integration, the fault current can be greatlyreduced by the increased resistance of the superconducting arm coils during fault condition. Wesimulate and compare the performance of the cryo-MMC and a conventional MMC under a DCsidepole-to-pole fault. The simulation results show that the Cryo-MMC reduces the DC-sidesurge current by 57\%, the peak arm currents by 65\%, and the peak AC-current by 73.7\% duringthe simulated fault. We also report the construction of the first cryo-MMC prototype that willexperimentally validate the integration of superconducting arm coils into a single-phase 6-levelMMC.
	Dead Time Management in GaN Based Three-Phase Motor Drives   By Fabio MANDRILE	[View]   [Download]
Abstract: This paper deals with the dead time selection in Gallium Nitride (GaN) FET based three-phase brushless DC motor drives. The GaN wide-bandgap (WBG) technology enables the increase of the switching frequency compared with silicon MOSFET. In inverter applications, it is necessary to insert a dead time in the switching signals, to avoid cross conduction in the inverter leg. The dead time selection is a compromise between the switching time and the quality of the inverter output waveforms. GaN FETs can operate with dead times in the range of tens of ns. In this paper the advantages of the GaN technology in the reduction of dead time in terms of output waveforms distortion and speed ripple compared with silicon MOSFET are carried out. Furthermore, an evaluation on the dead time compensation technique compared with the hardware technology reduction is investigated demonstrating the effectiveness and the saving of software and hardware resources obtained by GaN FET devices.
	Design Evaluation of Medium-Voltage and High-Power Modularized DC/DC Converters with SiC MOSFETs   By Gard LYNG RØDAL	[View]   [Download]
Abstract: This paper investigates the efficiency, performance, and design complexity of medium-voltage and high-power modularized dual active bridge (MDAB) converters employing high-voltage SiC MOSFETs and operating at high switching frequencies. The modelling of switching transients in terms of various timeintervals for SiC MOSFET power modules rated at 3.3 kV and 750 A are presented and compared withexperimental switching data. Based on these evaluations, the minimum deadtime intervals and maximumtheoretical switching frequency of 3.3 kV SiC MOSFETs employed in MDAB converters are estimated.
	EFFICIENCY AND TRANSFER FUNCTION CALCULATION OF THE BUCK-BOOST CONVERTER WITH IDEAL FLOW CONTROL   By Khalid JAVED	[View]   [Download]
Abstract: The voltage regulator is designed based on a transfer function of the system pre-converter with ideal current control. This transfer function is obtained by first obtaining the system equation for the pre-converter with ideal current control. Subsequently, we look for a possible regime solution for a sinusoidal power supply and then arrive at the transfer function via linearization of the system equation around the solution in regime. The calculations are verified by using Matlab/Simulink on the system with considering two buck boost converters connected in parallel. The control scheme used in simulation is feed forward control scheme.
	Efficiency Improvement Analysis of a SiC MOSFET-based PMSM Drive System with Variable Switching Frequency   By Suleman YUNUS	[View]   [Download]
Abstract: The widespread deployment of electric vehicles (EVs) requires high efficiency of traction inverters to drive longer distances in one charge. The widely used silicon insulated-gate bipolar transistor (Si IGBT) for EV motor drives is mature and practical; however, it can result in large inverter losses, especially at high switching frequencies. Whereby, silicon carbide metal-oxide-semiconductor field-effect transistors (SiC MOSFETs) can reduce both conduction and switching losses compared to Si IGBT. Increasing the switching frequency of the traction inverters is proven to be effective in lowering the motor iron losses; however, this will concurrently increase the inverter switching losses. This paper aims to show the effectiveness of operating SiC MOSFETs in a permanent magnet synchronous motor drive using variable switching frequency pulse-width modulation. Optimisation of the switching frequency is therefore demonstrated to maximise the motor drive system efficiency. Results show that the efficiency of the whole system, i.e., motor and motor drive, can be improved through optimally selecting the switching frequency of the motor drive at different driving operating points.
	Efficient Modeling Technique for Analysis of the Half Bridge DC-DC Converter   By Oguz TAHMAZ	[View]   [Download]
Abstract: An efficient approach for the analysis, modeling, and simulation of the Half-Bridge (HB) DC-DC converter circuit operating in continuous conduction mode (CCM) has been proposed. The efficiency of the method comes from modeling basic components in the converter properly. The center-tapped transformer, the most important component of the converter, is newly modeled by dependent sources. Parasitic effects of various components are also included in the analysis. In order to obtain system equations, being the basis of the analysis, the modified nodal method is used. Simulation results are presented as an illustration of the proposed modeling approach.
	EMI Filter for a Three-Phase 800 kHz Nine-Level Flying Capacitor GaN MultilevelInverter   By Raphael HARTWIG	[View]   [Download]
Abstract: This paper presents a Gallium Nitride (GaN) three-phase nine-level flying capacitor multilevel inverterwith a switching frequency of 800 kHz and a peak efficiency above 99 \%. The focus is on the noise spectrum and the EMI filter layout for the differential mode (DM) and the common mode noise (CM). Special attention is given to an analysis of different parasitic components and their effect on the resulting EMI spectrum.
	Energy-Balancing of a Modular Multilevel Converter with Pulsed DC Load Using an Online Trajectory Planning Algorithm   By Qiuye GUI	[View]   [Download]
Abstract: Modular Multilevel Converter (MMC) energy balancing is a nontrivial open-loop control problem since the choice of a technically meaningful output leads to an internal dynamics. A large voltage ripple on the dc side of an MMC may cause permanent arm power imbalances. For example, the large voltage ripple at the smoothing capacitor of a pulsed dc load can affect the supplying MMC. This paper focuses on the energy balancing task of MMCs supplying the smoothing capacitor of a pulsed dc load. The approach introduced in this paper is to define feasible stationary operating regimes with circulating current injection and plan appropriate trajectories solved analytically for all variables. This lends itself to an online implementation and provides a feedforward energy control supporting the standard feedback based energy balancing. Test bench measurements confirm improved energy control performance compared to standard feedback balancing.
	Experimental Characteristics of Capacitor Voltage Balancing Control in Modular Matrix Converter for Isolated Medium-Voltage AC-DC Converter   By Kohei BUDO	[View]   [Download]
Abstract: This paper presents capacitor voltage balancing control which compensate for capacitor voltage imbalance of a modular matrix converter for an isolated medium-voltage AC-DC converter. The power source and DC-load are not affected by proposed control method for balancing capacitor voltage imbalance. The effectiveness of this control method is verified by experiments using 5-kW laboratory prototype.
	Extended operating region of modular multilevel converters using full-bridgesub-modules   By Ygor PEREIRA MARCA	[View]   [Download]
Abstract: This paper presents an application of modular multilevel converters to remove line-frequency transformers from ultrafast charging stations, reducing cost and volume. The converter analysis with full-bridge sub-modules enables an operating region that converts a medium-voltage grid into a lower voltage DC-bus, ideal for charging batteries rapidly.
	GaN HEMT based 3L-ANPC drive System using a SynRM   By Martin GEPPERT	[View]   [Download]
Abstract: This paper presents a drive system based on a Gallium Nitride (GaN) 3-Level Active Neutral Point Clamped Converter (ANPC) and a Synchronous Reluctance Machine (SynRM). First, the ANPC hardware design using GaN HEMTs and the control system, which is implemented on a Zedboard (FPGA) is presented. Subsequently simulation and experimental results of a speed controlled SynRM drive are compared.
	High-Power Medium-Voltage Wind Turbine Driven by Converter Solution with Modular Multilevel Structure and Decentralized Battery Integration Operating in Both Gr   By Gustavo GONTIJO	[View]   [Download]
Abstract: Upscaling is a trend in the wind-power industry, which means to build wind turbines with increased power ratings and reduced structural costs. With the increased wind-turbine power levels, adopting a medium-voltage structure could be a solution to avoid problems related to high currents such as the intolerably high losses and the necessity of bulky, heavy, and expensive conductors. Moreover, a transformer-less wind turbine could be built due to the medium-voltage levels, which would contribute to the lightness and compactness of the entire solution. The high penetration of renewable-energy sources into the electrical grid leads to the necessity of energy-storage systems to assist in the preservation of the power-system stability. Wind power plants with energy-storage integration can operate in a dispatchable fashion, providing benefits to the operation of the power system such as the frequency-stability support, reduced voltage variations of the weak grid and the improvement of the economic dispatch. Furthermore, the wind-power-plant owner can improve his revenues by having an energy-storage system since it is possible to avoid penalties related to the mismatches between the forecasted power and the generated power, besides the possibility of providing ancillary services to the grid. Moreover, due to the presence of the energy-storage system, the wind power plant can keep active, generating power, if a fault occurs isolating the power plant from the main grid. In this paper, a new converter solution with modular multilevel structure and decentralized battery integration is used to drive a medium-voltage wind turbine. The integration of the batteries into the wind-turbine converter prevents the need of extra converters exclusively dedicated to the batteries. The wind turbine with energy storage can behave as a dispatchable generation when operating in the grid-following mode. In this mode, the wind turbine injects power into the grid according to a desired setpoint. When the wind power plant is isolated from the grid, the wind turbine driven by the new converter solution can operate in a grid-forming mode, absorbing the power generated by other wind turbines without an energy-storage system. In this paper, simulation results are shown illustrating the different operation modes of this new wind-turbine solution.
	Highly Compact 250 kVA Inverter Stack with 3.3 kV SiC MOSFETs   By Jürgen THOMA	[View]   [Download]
Abstract: This paper presents a 250 kVA three-level Active Neutral Point Clamped (ANPC) inverter stack with 3.3 kV SiC MOSFET modules for feeding into a 3 kV medium voltage grid. The high switching frequency of 16 kHz and the use of an active fluid cooling system with a synthetic ester lead to high power density.
	Highly Dynamic AC Current Control for Modular Multilevel Converters   By Dennis BRAECKLE	[View]   [Download]
Abstract: A highly robust and dynamic control of the MMC grid currents is necessary to ensure grid stability.Based on a state space modelling of the MMC, a real time capable indirect modelbased control is presented.Measurements with a laboratory setup show the reliability even under disturbed grid conditions.
	Hybrid MPPT Control Applied to a Push-Pull based pseudo DC-link PV microinverter   By Manuel DIAZ	[View]   [Download]
Abstract: This document presents a novel control scheme applied to a Push-Pull based pseudo DC-link PV microinverter, which consists of an hybrid MPPT algorithm, a PI control and a predictive control. The viability of the control proposal is checked through computer simulations.
	Isolated and Bidirectional Three-phase AC-DC Converter composed of Three Unfolding Bridges cascaded with a Quad-Active-Bridge Series-Resonant DC-DC converter   By Damian SAL Y ROSAS	[View]   [Download]
Abstract: A novel single-stage isolated and bidirectional three-phase AC-DC converter is proposed. The structure is composed of three unfolding bridges cascaded with a Quad-Active-Bridge Series-Resonant (QABSR) DC-DC converter. Proposed modulation allows minimum high frequency (HF) current and a decoupled control for the grid currents. Simulation results are shown to validate the converter functionality.
	Laboratory Tests results of a 50 kVA Soft Open Point prototype   By Serge GAVIN	[View]   [Download]
Abstract: RE (Romande Energie), a Swiss DSO (Distribution System Operator), is developing REEL (Réseau enEquilibre Local, French acronym for Network in Local Balance), a demonstration site which will allowto test several innovative technologies. In this contest, a 50 kVA SOP (Soft Open Point) converter hasbeen designed and built by the Universities of Applied Sciences of Western Switzerland (HES SO) ofYverdon-les-Bains and Fribourg. This prototype has been installed on the REEL site of Chapelle-sur-Moudon (Vaud, Suisse), in the first quart of 2021. In this paper, the main hardware and software features,the laboratory tests and the preliminary results of the field tests of the SOP system are presented. Experiments demonstrate the good performances of the SOP control and its usefulness in performing a suitable PQ control.
	Low Voltage Stress Three-phase 5-Level E-Type Multilevel-Multicell Converter for Medium-Voltage Applications   By Marco DI BENEDETTO	[View]   [Download]
Abstract: This paper proposes a 3-Phase 5-Level Multicell E-Type Converter (3F5L ME-Type) for medium-voltage applications. The proposed converter has each phase being accomplished by the combination of two I-Type cells connected to the Neutral Point Clamped (NPC) cell. The 3F5L ME-Type topology can improve the voltage stress of the power semiconductors, allowing to increase the DC-bus voltage. Operation modes and characteristics of the proposed converter are presented, and the theoretical investigation has been validated through the realized model in the Hardware-In-the-Loop (HIL) test bench. The performance of the proposed converter has been estimated through the created thermal model in Plexim/PLECS environment of the selected power semiconductors. The results show good performance and the effectiveness of the proposed converter to reduce the power semiconductor voltage stress compared to the previously E-Type Topology.
	Modular Resonant 25 kV - 8 A Power Converter for Particle Accelerator Application: Realisation and Operation   By Louis DE MALLAC	[View]   [Download]
Abstract: This paper presents the realisation of a 25 kV DC 200 kW power converter designed at CERN to supply radio frequency (RF) amplifiers for a particle accelerator application. The architecture is based on an N+1 redundant and modular structure in order to increase the availability of the system. The converter topology is a resonant LCC full-bridge inverter supplying a step-up medium-frequency transformer and a high voltage rectifier. It focuses on the hardware and control implementation, and how the resonant circuit can naturally achieve a smooth transition in case of module failure.These new power converters have been used in operation during two years and the design has proven its reliability. They are able to provide twice the power of the previous converters, and therefore allow the RF cavities to cope with the higher beam intensity required by the CERN LHC Injectors Upgrade project (LIU).
	New Series of Single-Phase Symmetric/Asymmetric Multilevel Inverter Topologies with Reduced Number of Power Switches   By Babak ROOHOLAHI	[View]   [Download]
Abstract: This paper proposes new series of two-stage single-phase multilevel inverter (MLI) topologies that are expandable to generate the desired number of voltage-levels. The isolated DC voltage sources charge the capacitors in the inputs of the presented topologies. The proposed MLIs consist of two parts, a voltage-level generator and an H-bridge inverter. The model predictive control is applied to control the switches. Reduction in the number of utilized power semiconductor devices to provide a high-quality multilevel output voltage and low rate of total harmonic distortion (THD) are the main features of the presented topologies. The PSCAD simulation results verified the performance of the proposed inverter. The comparison results show the reduction of the THD and the number of power switches.
	Novel Transformer-Based Six-Level Inverter with Low Component Count   By Ahmed SALEM	[View]   [Download]
Abstract: This paper proposes a single-source three-phase transformer-based inverter topology with a reduced component count. The key advantages of the proposed topology include simple structure, boosting feature, low component count, removing flying capacitors and being a diode-free circuit. Those merits reduce the inverter volume and complexity while enhancing efficiency and reliability. Despite presenting both six-level and N-level configurations of the proposed topology in this paper, only the six-level configuration is studied in detail and selected as a case study. Its structure, operating principle, and key results are provided. Further, a comparative study is provided to highlight its salient merits against its counterparts.
	Optimizing transformer parasitics in an inductor-less resonant converter   By Philippe MOREY	[View]   [Download]
Abstract: In this paper, the optimization of a 10 kW serial MPPT DC/DC converter designed to inject solar power into a low-voltage DC-microgrid is presented. The prototype was designed as two cascaded stages; an interleaved multi-branch boost topology followed by an inductor-less resonant topology. Traditionally, resonant converters use an external inductor, separating the resonant tank from the transformer. This has practical reasons but also has the drawback of an additional component and added weight. For this reason, the design exploits the leakage inductance of the transformer. However, the first prototype was overheating even in no-load conditions.This paper presents the optimization study conducted to eliminate this overheating. The analysis and simulations performed allowed to identify and pinpoint the source of the issue, namely highlighting the role of the parasitic capacitances in the high di/dt current step in the transformer. Simulations where first done to rough out the problem and get a better understanding of the different interactions between various parasitic elements. A literature review was conducted, and a theoretical analysis method was then applied. This allowed to estimate the order of magnitude of the transformer's parasitic capacitances and helped fine tune the simulation model. Based on the performed analysis, recommendations and specifications were prepared for a new transformer. An new optimized transformer was then built and tested. The results were better than expected. The parasitics were reduced by 90\%, showing that the issue had correctly been identified and addressed.
	Proactive SoC Balancing Strategy for Battery Modular Multilevel Management (BM3) Converter Systems and Reconfigurable Batteries   By Ali MASHAYEKH	[View]   [Download]
Abstract: The battery modular multilevel management converter topology and different types of reconfigurable battery topologies have been proven to be a viable option for various electric power applications. This paper presents a unique SoC balancing approach for the integrated battery strands/packs of BM3 converter systems or reconfigurable batteries. The suggested approach alternately utilizes different redundant switching state combinations to balance and to keep the battery strands' SoCs balanced. Furthermore, the suggested algorithm attempts to utilize all converter modules, because the parallel connection of adjacent modules reduces the phase-strand's battery impedance. Furthermore, the presented approach tries to reduce the number of switching events when changing the switching state combination. Thereby, the ohmic battery losses and switching losses are kept as low as possible. Since no power is dissipated in designated bleeder resistors and no designated active balancing circuitry is required, the suggested approach can be categorized as a proactive balancing approach. Simulations are used to verify the algorithm's validity.
	Proposal of Model predictive control for Single phase PFC to achieve low current distortion and high response DC voltage control   By Nagisa OSHIRO	[View]   [Download]
Abstract: AC-DC converters to which DC voltage from a single-phase AC source are used in various applications. Onthe other hand, the harmonic current generated by these converters with PI controller is regarded as a problem.We would like to propose to use the model predictive control instead of PI controllers for PFC in order tosuppress harmonic current.
	Reactive Power Availability of a Three Level Three Phase 20 kW PFC   By Akshay MAHAJAN	[View]   [Download]
Abstract: Three phase rectifiers are gaining importance with the increase in charging infrastructure demand for EVs. This paper proves the reactive power availability of a three phase three level unidirectional rectifier consisting only two active switches per phase, with a power factor up to +- 0.9. Each phase leg of the converter is connected to the grid with a L-C-L filter and the filter star point of the capacitors is connected to the middle point of the DC link. The neutral of the grid being not connected to the start point of the filter capacitors enables start point modulation. In this paper, a current controller is proposed for the star point modulation with two main objectives; achieving a desired power factor and minimizing the DC link voltage. Detailed mathematical derivations and simulation results proving the reactive power availability of the converter are presented.
	Safe operation of a totem-pole PFC converter using depletion-mode GaN HEMTs   By Romain MONTHEARD	[View]   [Download]
Abstract: This paper presents the design and realization of a totem-pole PFC converter featuring depletion-mode GaN-on-Si power transistors, with a focus on an original approach to safely tackle the challenges related to the normally-ON characteristic. The realized converter takes full advantage of these power devices while ensuring safe operation.
	Sensitivity Analysis of a Non-Symmetrical Resonant Converter with Frequency and Phase-Shift Closed Loop Control for Battery Charging   By Alex MIRTCHEV	[View]   [Download]
Abstract: In this paper, a sensitivity analysis of a non-symmetrical resonant converter for battery charging is presented. _he effects of the resonant tank parameters on the output power and the control variables is examined through sensitivity analysis. Pulse frequency modulation (PFM) and phase-shift modulation (PSM) techniques are implemented to control the converter output. A sensitivity analysis is conducted for the whole frequency spectrum and different operation conditions. The sensitivity coefficients of the output power and the control variables are calculated with respect to crucial parameters of the resonant tank. An experimental prototype is implemented to verify the sensitivity analysis and the control method.
	SM Insertion Time Based Capacitance Monitoring in Modular Multilevel Converters   By Jifeng ZHAO	[View]   [Download]
Abstract: This paper proposed a sorting-based condition monitoring strategy for capacitors of submodule (SM) in modular multilevel converters (MMCs). It reveals the relationship between the capacitor's capacitance and SM insertion time. Based on the relationship, the capacitances of SM capacitors in the arm are indirectly sorted, and only the capacitor with smallest capacitance in the arm are monitored. The proposed strategy not only realizes capacitance monitoring in MMCs for sorting-based method, but also proposes a simplified monitoring algorithm for MMCs with large number of capacitors. The simulation and experimental results confirm the effectiveness of the proposed monitoring strategy for MMCs.
	Turn-off overvoltage characterization and mitigation in wide bandgap power transistors   By Junyun DENG	[View]   [Download]
Abstract: Turn-off ringing is a challenge caused by parasitic elements in power loop, resulting in switchinglosses, voltage breakdown and EMI issues. A worse case occurs while employing wide bandgappower transistors due to their fast turn-off. The conventional way to mitigate turn-off ringing isto reduce the commutation loop inductance or slow down transistors' switching speed. However,slow turn-off speed is undesirable due to low switching loss. In this work, it is demonstrated thatfast turn-off of wide bandgap(WBG) transistors can facilitate minimizing voltage overshoot withwell-tuned parasitic loop inductance. Based on the characterization of the turn-off transition,an analytical model is derived that shows voltage overshoot can be reduced without sacrificinglow turn-off loss and simple PCB layout while allowing high loop inductances. The proposedtechnology can fully exploit the potential of wide bandgap transistors in extremely fast switchingconditions.