Showing papers on "Flyback converter published in 2017"
TL;DR: In this paper, a high-voltage gain dc-dc converter is introduced, which resembles a two-phase interleaved boost converter on its input side while having a Dickson-charge-pump-based voltage multiplier (VM) on its output side.
Abstract: A high-voltage-gain dc–dc converter is introduced in this paper. The proposed converter resembles a two-phase interleaved boost converter on its input side while having a Dickson-charge-pump-based voltage multiplier (VM) on its output side. This converter offers continuous input current, which makes it more appealing for the integration of renewable sources like solar panels to a 400-V dc bus. Also, the proposed converter is capable of drawing power from either a single source or two independent sources. Furthermore, the VM used offers low voltage ratings for capacitors that potentially leads to size reduction. The converter design and component selection have been discussed in detail with supporting simulation results. A hardware prototype of the proposed converter with ${V}_{\rm{in}}= \rm{ 20}$ and ${V}_{\rm{out}}= \rm{ 400}$ V has been developed to validate the analytical results.
155 citations
TL;DR: This paper presents a novel 400 to 12 V isolated bidirectional dc–dc converter based on a phase-shift-controlled-modified dual-active-bridge power stage, which has promising performance for low-voltage high-current applications.
Abstract: This paper presents a novel 400 to 12 V isolated bidirectional dc–dc converter based on a phase-shift-controlled-modified dual-active-bridge power stage. The proposed converter consists of a half-bridge and center tap with active clamp circuit, which has promising performance for low-voltage high-current applications. 650 V gallium-nitride high electron mobility transistors are used on the high voltage side to avoid issues encountered using Si superjunction MOSFETs in phase-shift-controlled-bidirectional power conversions. The operation principle and power transfer characteristic are obtained based on a time-domain analysis of the inductor current. Design methodology and criteria and converter's efficiency analysis are discussed. Both the analysis and experiments verify that the proposed converter is capable of achieving low power loss and high power density in soft-switching and hard-switching modes. Experimental results are presented for a 1-kW, 400 V-to-12 V dc–dc prototype converter operating at 100 kHz switching frequency. A power density of 30 W/in3 and a peak efficiency of 98.3% in a wide input/output voltage range are achieved.
149 citations
TL;DR: An automatic any-cells-to-any-cells battery equalizer, which merges the forward and flyback converters through a common multiwinding transformer, which overcomes the mismatching problem of multiple windings and can reach up to 89.4% over a wide range of conditions.
Abstract: This paper proposes an automatic any-cells-to-any-cells battery equalizer, which merges the forward and flyback converters through a common multiwinding transformer. The windings of the transformer are divided into two groups, which have opposite polarities. The principles of the proposed equalizer are that the equalization in one group is achieved based on forward conversion and the balancing between the two different groups is based on flyback conversion, by which the magnetic energy stored in the transformer can be automatically reset without using additional demagnetizing circuits. Moreover, only one MOSFET and one primary winding are required for each cell, resulting in smaller size and lower cost. One pair of complementary control signals is employed for all MOSFETs, and energy can be automatically and directly delivered from any high-voltage cells to any low-voltage cells without the requirement of cell monitoring circuits, thereby leading to a high balancing efficiency and speed. The proposed topology can achieve the global equalization for a long battery string through connecting the secondary sides of transformers without the need of additional components for the equalization among modules, which also overcomes the mismatching problem of multiple windings. The validity of the proposed equalizer is verified through experiments, and the balancing efficiency can reach up to 89.4% over a wide range of conditions.
147 citations
Abstract: This paper presents a real-time coordinated control of the hybrid ac/dc microgrids involving energy storage and pulsed loads. Grid-isolated hybrid microgrid applications require special considerations due to the intermittent generation, online energy storage control, and pulsed loads. In this study, we introduce a comprehensive frequency and voltage control scheme for a hybrid ac/dc microgrid consisting of a synchronous generator, solar generation emulator, and bidirectional (ac/dc and dc/dc) converters. A bidirectional controlled ac/dc converter with an active and reactive power decoupling technique is used to link the ac bus with the dc bus, while regulating the system voltage and frequency. A dc/dc boost converter with a maximum power point tracking function is implemented to maximize the intermittent energy generation from solar generators. Current-controlled bidirectional dc/dc converters are applied to connect each lithium-ion battery bank to the dc bus. Lithium-ion battery banks act as energy storage devices that serve to increase the system resiliency by absorbing or injecting power. Experimental results are presented for verification of the introduced hybrid ac/dc power flow control scheme.
142 citations
TL;DR: Analysis of the converter operation and the stability in the step-up and step-down operating modes through the state-space averaging method and through the pulse width modulation switch model method applied on an equivalent circuit model proves that the controller is able to track the reference current waveform with good dynamic performance.
Abstract: This paper focuses on a bidirectional hybrid dc–dc converter suitable as an interface between two dc voltage buses in various applications including microgrids. The switched-capacitor cell, incorporated in the converter topology, gives the advantage of high voltage conversion ratio without using a transformer. This paper analyses the converter operation and the stability in the step-up and step-down operating modes through the state-space averaging method and through the pulse width modulation switch model method applied on an equivalent circuit model. The converter employs a current controller designed in frequency domain based on the Bode plot, using the K factor method. The simulation results obtained by means of an average and a detailed switching model prove, in good correspondence, that the controller is able to track the reference current waveform with good dynamic performance . Experimental results obtained from a 2 kW converter prototype confirm the theoretical considerations and the simulation results.
137 citations
TL;DR: In this article, a multi-input dc-dc converter is proposed and studied for hybrid electric vehicles, which has the capability of providing the demanded power by load in absence of one or two resources.
Abstract: In this paper, a multiinput dc-dc converter is proposed and studied for hybrid electric vehicles. Compared to conventional works, the output gain is enhanced. Fuel cell (FC), photovoltaic panel, and energy storage system are the input sources for the proposed converter. The FC is considered as the main power supply, and roof-top PV is employed to charge the battery, increase the efficiency, and reduce fuel economy. The converter has the capability of providing the demanded power by load in absence of one or two resources. Moreover, the power management strategy is described and applied in a control method. A prototype of the converter is also implemented and tested to verify the analysis.
137 citations
TL;DR: A novel transformerless buck-boost dc-dc converter that has simple structure and the low on-state resistance of the power switch can be selected to decrease conduction loss of the switch and improve efficiency.
Abstract: A novel transformerless buck–boost dc–dc converter is proposed in this paper. The presented converter voltage gain is higher than that of the conventional boost, buck–boost, CUK, SEPIC, and ZETA converters, and high voltage can be obtained with a suitable duty cycle. In this converter, only one power switch is utilized. The voltage stress across the power switch is low. Hence, the low on-state resistance of the power switch can be selected to decrease conduction loss of the switch and improve efficiency. The presented converter has simple structure, therefore, the control of the proposed converter will be easy. The principle of operation and the mathematical analyses of the proposed converter are explained. The validity of the presented converter is verified by the experimental results.
135 citations
TL;DR: The experimental results validate the feasibility of the proposed topology and its suitability for fuel cell vehicles.
Abstract: An input-parallel, output-series dc–dc Boost converter with a wide input voltage range is proposed in this paper. An interleaved structure is adopted in the input side of this converter to reduce input current ripple. Two capacitors are connected in series on the output side to achieve a high voltage gain. The operating principles and steady-state characteristics of the converter are presented and analyzed in this paper. A 400 V/1.6 kW prototype has been created which demonstrates that a wide range of voltage gain can be achieved by this converter and it is shown that the maximum efficiency of the converter is 96.62% and minimum efficiency is 94.14%. The experimental results validate the feasibility of the proposed topology and its suitability for fuel cell vehicles.
131 citations
TL;DR: It is demonstrated that non-isolated dc-dc converters based on the conventional Boost converter can be treated as a unique generalized converter, called Boost Converter with Gain Cell (BCGC).
Abstract: High step-up conversion is an indispensable feature for the power processing of low voltage renewable sources in grid-connected systems. Motivated by this necessity, this paper presents a study on non-isolated dc-dc converters based on the conventional Boost converter that can provide such feature with high efficiency. By the topological variation and gain cell concepts, it is demonstrated that these converters can be treated as a unique generalized converter, called Boost Converter with Gain Cell (BCGC). The operating principle, the key waveforms and the components stresses of the BGCG are analyzed for the continuous-conduction mode, independently of the employed gain cell. A methodology to create the gain cells is developed from the combination of coupled inductors and voltage multiplier techniques. In order to verify the realized analysis, a 150 W prototype concerning to the proposed generalized converter and able to operate with several different gain cells is developed for the comparison between theoretical and experimental static gain results.
129 citations
TL;DR: In this paper, the authors proposed a novel balancing approach for an electric vehicle bipolar dc charging station at the megawatt level, enabled by a grid-tied neutral-point-clamped converter.
Abstract: This paper proposes a novel balancing approach for an electric vehicle bipolar dc charging station at the megawatt level, enabled by a grid-tied neutral-point-clamped converter. The study uses the presence of an energy storage stage with access to both of the dc buses to perform the complementary balance. It proposes a generic balancing structure that can achieve balance regardless the kind of energy storage system (ESS) employed. This is aiming to reduce the hardware requirements of the system and maximize the usage of the ESS, whose main function is to perform the energy management related tasks. To meet this purpose, a three-level dc–dc interface is employed, allowing to compensate the dc currents with a single ESS. Furthermore, in order to prevent the appearance of even-order harmonics in the input current during asymmetrical operation, an alternative switching sequence for the central converter is proposed. Results indicate that, without altering dramatically the charging process of the ESS, it is possible to cover the whole load scenario without the need of a balancing circuit. This allows the use of off-the-shelf products both for the rectifier and the fast chargers. In this paper, simulation and experimental results are presented to validate the proposed balancing strategy.
126 citations
TL;DR: In this article, a three-port dc/dc converter for hybrid photovoltaic (PV)/fuel cell (FC)/battery applications is presented, which comprises a conventional buck-boost and a boost converter.
Abstract: In this paper, a new three-port dc/dc converter is presented for hybrid photovoltaic (PV)/fuel cell (FC)/battery applications. The proposed structure comprises a conventional buck-boost and a boost converter. Four power switches and four diodes are employed in the proposed converter. The voltage gain of the presented converter is more than the conventional boost converter. This advantage and having two unidirectional and a bidirectional inputs make the structure a suitable power electronic interface for hybrid generation applications. In addition, there are no limitations in switching the modulation. Therefore, tracking the maximum power of the PV source, setting the FC power, controlling the battery power, and calibrating the output voltage can be equipped by controlling duty ratios of the switches. The input power sources can provide power to the load and either charge or discharge the battery individually or simultaneously. The steady-state analyses of the presented converter are discussed thoroughly in this paper. Finally, in order to validate the feasibility of the presented converter, experimental results are provided.
TL;DR: In this paper, a multilevel high-frequency-link dc transformer (MDCT) based on dual active phase-shift principle for medium-voltage dc (MVDC) power distribution application is proposed.
Abstract: This paper proposes a multilevel high-frequency-link dc transformer (MDCT) based on dual active phase-shift principle for medium-voltage dc (MVDC) power distribution application. The proposed MDCT employs multilevel and multiplex conversion principle, which brings many advantages and makes the operation of MDCT quite different with the traditional dc transformer (TDCT) and modular multilevel converter. Compared to the TDCT scheme, the proposed MDCT has smaller circulating current and higher power factor; it can operate as a dc breaker to cutoff the connection with the MVDC distribution grid absolutely when a short fault occurs in the distribution grid; the redundant design can be achieved when some submodules failure to improve the reliability. In the paper, the topology, operation principle, modulation method, switching characterization, voltage, and power characterization, and control strategy of MDCT are presented and analyzed comprehensively. At last, a MDCT prototype is built and the experimental results verify the correctness and effectively of the proposed solution.
TL;DR: In this paper, a single-switch non-isolated dc-dc converter with very high voltage gain and reduced semiconductor voltage stress is presented, which utilizes an integrated autotransformer and a coupled inductor on the same core.
Abstract: This paper introduces a new single-switch nonisolated dc–dc converter with very high voltage gain and reduced semiconductor voltage stress. The converter utilizes an integrated autotransformer and a coupled inductor on the same core in order to achieve a very high voltage gain without using extreme duty cycle. Furthermore, a passive lossless clamp circuit recycles the leakage energy of the coupled magnetics and alleviates the voltage spikes across the main switch. This feature along with low stress on the switching device enables the designer to use a low voltage and low R DS-on MOSFET, which reduces cost, as well as conduction and turn on losses of the switch. The principle of operation, theoretical analysis, and comparison supported by some key simulation and experimental results of a 500 W prototype are presented.
TL;DR: In this paper, the authors describe the analysis and design of a series-resonant dc-dc converter, which is particularly interesting for high-power applications, given its tight input-to-output transfer characteristics and its capability to ensure soft-switching transitions of all semiconductor devices.
Abstract: In the solid-state transformer (SST) concept, the key task of voltage adaptation and isolation is performed by a high-power dc–dc converter, which is operated in the medium-frequency range, hence enabling a reduction in size and weight of the converter's reactive components. This dc–dc converter presents the main challenge in the implementation of the SST concept, given its operation at medium frequency together with the direct connection to medium voltage. This combination demands the utilization of dc–dc converter topologies that are able to operate in the soft-switching mode, whereby, given that typically insulated-gate bipolar transistor switches are used as power devices, zero-current switching modulation schemes become highly attractive and often mandatory in order to achieve the targeted efficiency goals. This paper describes in detail the analysis and design of a 166-kW/20-kHz dc–dc converter of the series-resonant type, which results to be particularly interesting for high-power applications, given its tight input-to-output transfer characteristics and its capability to ensure soft-switching transitions of all semiconductor devices. The main focus of this paper is to describe in detail the practical implementation of the aforementioned resonant dc–dc converter, where its main components, i.e., the medium- and low-voltage-side power bridges and the medium-frequency transformer, are described independently. The assembled prototype is presented together with the implemented testing strategy and the final experimental results.
TL;DR: In this paper, a novel ultralarge gain step-up coupled-inductor dc/dc converter with an asymmetric voltage multiplier network is presented for a sustainable energy system.
Abstract: In this paper, a novel ultralarge gain step-up coupled-inductor dc/dc converter with an asymmetric voltage multiplier network is presented for a sustainable energy system. The proposed converter contains one boost converter, one voltage multiplier network, and one passive lossless clamped circuit. In order to achieve an ultralarge voltage gain, one of the two capacitors is charged by the primary side and secondary side of the coupled inductor, then it together with the secondary side of coupled inductor provides its energy for the other capacitor in voltage multiplier network. Besides, the passive lossless clamped circuit not only recycles leakage energy but also effectively reduces the voltage stress on the main switch. By this way, the efficiency of the conversion can be improved. Moreover, the reverse-recovery problem of the diodes in the leakage inductor is alleviated. The operating principles and steady-state analyses are illustrated in detail. Then, the performance of the proposed converter is compared with existing converters. Finally, a prototype circuit at 50-kHz switching frequency with 20-V input voltage, 200-V output voltage, $N = 2$ , and 200-W output power is established in the laboratory to verify the performance of the proposed converter.
TL;DR: In this paper, a quasi-Z-source series resonant dc-dc converter is proposed for photovoltaic module-level power electronics applications, where the shoot-through pulse width modulation and phase shift modulation are combined in a single switching stage to realize the boost and buck operating modes.
Abstract: This paper presents the high-performance quasi-Z-source series resonant dc-dc converter as a candidate topology for the photovoltaic module-level power electronics applications. The converter features a wide input voltage and load regulation range thanks to the multimode operation, i.e., when the shoot-through pulse width modulation and phase-shift modulation are combined in a single switching stage to realize the boost and buck operating modes, respectively. Our experiments confirmed that the proposed converter is capable of ensuring ripple-free 400 V output voltage within the sixfold variation of the input voltage (from 10 to 60 V). The converter prototype assembled achieved a maximum efficiency of 97.4%, which includes the auxiliary power and control system losses.
TL;DR: In this paper, the authors proposed a new boost composite converter approach to address the dominant loss mechanisms associated with indirect power conversion, resulting in fundamental efficiency improvements over wide ranges of operating conditions.
Abstract: In a hybrid or electric vehicle powertrain, a boost dc–dc converter enables reduction of the size of the electric machine and optimization of the battery system. Design of the powertrain boost converter is challenging because the converter must be rated at high peak power, while efficiency at medium-to-light load is critical for the vehicle system performance. By addressing only some of the loss mechanisms, previously proposed efficiency improvement approaches offer limited improvements in size, cost, and efficiency tradeoffs. This paper shows how all dominant loss mechanisms in automotive powertrain applications can be mitigated using a new boost composite converter approach. In the composite dc–dc architecture, the loss mechanisms associated with indirect power conversion are addressed explicitly, resulting in fundamental efficiency improvements over wide ranges of operating conditions. Several composite converter topologies are presented and compared to state-of-the-art boost converter technologies. It is found that the selected boost composite converter results in a decrease in the total loss by a factor of 2–4 for typical drive cycles. Furthermore, the total system capacitor power rating and energy rating are substantially reduced, which implies potentials for significant reductions in system size and cost.
TL;DR: In this paper, a new structure for high step-up dc–dc converters is proposed and it is possible to extend the topology by increasing the number of active–passive inductor cells.
Abstract: In this paper, a new structure for high step-up dc–dc converters is proposed. In the proposed structure, it is possible to extend the topology by increasing the number of active–passive inductor cells. High voltage gain with lower duty cycle, low-current and -voltage stresses on switches, small inductors, and small size of filter are the main advantages of the proposed structure. The proposed converter is analyzed in different operating modes. In order to design the components’ values of the proposed converter, the equations of output voltage ripple are calculated in each operating mode and a design procedure is proposed based on the aforementioned equations. Moreover, the losses and efficiency of the converter are calculated. In order to validate the correctness of calculations and analyses, the experimental results are given.
26 Mar 2017
TL;DR: In this paper, a high efficiency and high power density sigma converter for 48/1V voltage regulator module (VRM) is proposed, which is a quasi-parallel converter that uses a high-efficiency unregulated converter to deliver most power to the load with small power flowing through buck converter responsible for regulating the output voltage.
Abstract: A high efficiency and high power density sigma converter for 48/1V voltage regulator module (VRM) is proposed in this paper. The Sigma converter is a quasi-parallel converter that uses a high efficiency unregulated converter to deliver most power to the load with small power flowing through buck converter responsible for regulating the output voltage. The unregulated isolated converter is LLC converter designed with matrix transformer structure integrating 4 transformers in one core structure with integrating the Synchronous Rectifiers (SRs) with the winding to minimize the termination losses of the transformer so a high efficiency can be achieved. The buck converter is designed with discrete GaN devices and PCB winding inductor to regulate the output voltage. The designed Sigma converter is 48/1V-80A achieving a power density of 420W/in3 and maximum efficiency of 93.4%.
TL;DR: In this paper, a novel isolated dc-dc converter topology for medium-voltage (MV) applications is proposed by combining the advantages of resonant converters and dual active bridge (DAB) converters.
Abstract: In this paper, a novel isolated dc-dc converter topology for medium-voltage (MV) applications is proposed by combining the advantages of resonant converters and dual active bridge (DAB) converters. In normal load scenario, this converter operates in an open loop resonant mode with a fixed switching frequency equals to the resonant frequency of the series resonant tank. Thus, zero voltage turn on at primary side and zero current turn off at secondary side are secured from zero to full load. When overload happens, the resonant capacitors will be clamped to the output voltage by the additional paralleled diodes. The proposed converter automatically switches to resonant and DAB mixed operation mode; therefore, the resonant current is naturedly limited. With zero to full load range soft switching and fast overload protection, the proposed topology is especially suitable for MV medium frequency applications utilizing high-voltage SiC MOSFETs. The converter operation modes are analyzed using time-domain waveforms and graphical state trajectory to derive the quantitative relationship between duty cycle, output voltage, and the overload current. Based on these relationships, a predictive duty cycle control is proposed to further limit the overload current of the resonant tank by sensing the output voltage. Combing the proposed topology and the predictive control, cycle-by-cycle overload and short-circuit protections are achieved. To fully utilize the capability of the 15-kV SiC MOSFET, magnetizing inductance, dead time, MV transformer, and resonant components are optimized with the operating range of 6-12 kV and 20-100 kHz. An experimental prototype running at 6 kV and 40 kHz is successfully tested with peak efficiency exceeding 98%. Test waveforms at no load and 10-kW full load validate the zero to full load range soft switching capability. Short circuit protection test demonstrates a 25-us overload protection speed.
TL;DR: The proposed converter is designed as a series resonant converter with nominal-input voltage and operates under two additional modes: a boost converter with low- input voltage and a buck converter with high-input Voltage.
Abstract: A microconverter serves as a front-end dc–dc stage of a microinverter to convert the power from a photovoltaic module to a dc bus. These front-end microconverters require isolation, high-boost ratio, wide-input voltage regulation, and high efficiency. This paper introduces an isolated resonant converter with hybrid modes of operation to achieve wide-input regulation while still maintaining high efficiency. The proposed converter is designed as a series resonant converter with nominal-input voltage and operates under two additional modes: a boost converter with low-input voltage and a buck converter with high-input voltage. Unlike conventional resonant converters, this converter operates at discontinues conduction mode with a fixed frequency, simplifying the design and control. In addition, this converter can achieve zero-voltage switching (ZVS) and/or zero-current switching (ZCS) of the primary-side MOSFETs, ZVS and/or ZCS of the secondary-side MOSFETs, and ZCS of output diodes under all operating conditions. Experimental results using a 300-W prototype achieve a peak efficiency of 98.1% and a California Energy Commission efficiency of 97.6% including all auxiliary and control power at nominal-input voltage.
TL;DR: In this article, a dc-dc modular multilevel converter (dc-dc MMC) with a medium-frequency ac-link transformer is proposed for the modern electric ship medium voltage dc power system to provide galvanic isolation, flexible voltage regulation, and fault ride through ability.
Abstract: The dc-dc modular multilevel converter (dc-dc MMC) with a medium-frequency ac-link transformer is a promising candidate for the modern electric ship medium voltage dc power system to provide galvanic isolation, flexible voltage regulation, and fault ride through ability. However, the steady states and dynamics of such an isolated dc-dc MMC are rather complicated because it contains many state variables. Moreover, the on-ship requirements further complicate the system design. This paper thus proposes the modeling and control of such a dc-dc MMC. Based on the fact that such a dc-dc MMC is controlled by the phase-shifted operation, the fundamental period averaging (FPA) method is applied to obtain the steady-state and small-signal models, and based on the on-ship requirements, the modulation index control as well as the simple but efficient competitive dual closed loops (a voltage loop for normal condition and a current loop for overload condition) are designed. It is proved that the FPA method can preserve the necessary model information about the dc-dc MMC, and the proposed controllers can be well designed based on the steady-state and small-signal FPA models by compromising the on-ship requirements. The analysis and design results are verified by the simulations and experiments.
TL;DR: In this article, a high step-up pulse width modulation dc-dc converter integrating coupled-induction and switched-capacitor (SC) techniques is presented, which consists of a synchronous rectification Boost unit and multiple coupled-Induction-SC units.
Abstract: In this paper, a novel high step-up pulse width modulation dc–dc converter integrating coupled-inductor and switched-capacitor (SC) techniques is presented. The proposed converter consists of a synchronous rectification Boost unit and multiple coupled-inductor-SC units. Its structure can therefore be easily extended for ultrahigh voltage gain. The diodes employed in the proposed converter can operate under soft-switching condition by utilizing leakage inductance of the coupled inductor. Low-voltage-rated transistors can be used to improve the efficiency as the voltage stress on the main switches of the proposed converter is reduced. The feasibility of the proposed converter is experimentally demonstrated by a 200 W prototype converter.
TL;DR: In this paper, a boost three-level dc-dc converter with a diode rectification quasi-Z source (BTL-DRqZ) is presented to solve the problem of mismatched voltage levels between the dynamic lower voltage of the fuel cell stack and the required constant higher voltage (400 V) of the dc-link bus of the inverter for fuel cell vehicles.
Abstract: To solve the problem of the mismatched voltage levels between the dynamic lower voltage of the fuel cell stack and the required constant higher voltage (400 V) of the dc-link bus of the inverter for fuel cell vehicles, a boost three-level dc–dc converter with a diode rectification quasi-Z source (BTL-DRqZ) is presented in this paper, based on the conventional flying-capacitor boost three-level dc–dc converter. The operating principle of a wide range voltage-gain for this topology is discussed according to the effective switching states of the converter and the multiloop energy communication characteristic of the DRqZ source. The relationship between the quasi-Z source net capacitor voltages, the modulation index, and the output voltage is deduced and then the static and dynamic self-balance principle of the flying-capacitor voltage is presented. Furthermore, a boost three-level dc–dc converter with a synchronous rectification quasi-Z source (BTL-SRqZ) is additionally proposed to improve the conversion efficiency. Finally, a scale-down 1.2 kW BTL-SRqZ prototype has been created, and the maximum efficiency is improved up to 95.66% by using synchronous rectification. The experimental results validate the feasibility of the proposed topology and the correctness of its operating principles. It is suitable for the fuel cell vehicles.
TL;DR: The illustrated results show that DT-ATAB can be used as a promising multiport converter to interface the multiple sources and load to achieve wide-ranging outputs with the minimal losses.
Abstract: In this paper, a dual-transformer-based asymmetrical triple-port active bridge converter (DT-ATAB) is proposed to interface two different dc-sources and a load. DT-ATAB consists of three active power electronic converters and two high-frequency transformers. All switches of these converters can be turned on with zero-voltage switching to reduce the switching losses. The bidirectional power flow operation is possible between the ports. The DT-ATAB also reduces the circulating powers between the ports for well-matched transformer turns ratios as compared to those in the other existing triple-port active bridge converters (TAB). Furthermore, the magnetic short-circuit conditions arising in the three-winding transformer of the TAB are mitigated in DT-ATAB. The principle of operation, steady-state analysis, various modes of operation (three-port and two-port modes), and a closed loop controller of DT-ATAB are presented. The theoretical analysis of this paper is verified using both simulation and experimental studies. The illustrated results show that DT-ATAB can be used as a promising multiport converter to interface the multiple sources and load to achieve wide-ranging outputs with the minimal losses.
TL;DR: In this paper, two commercially available silicon carbide (SiC) MOSFETs were evaluated using a load inductance of 1.42, 5.1, 10.5, and 15.8 mH.
Abstract: Commercialization of 1200-V silicon carbide (SiC) MOSFET has enabled power electronic design with improved efficiency as well as increased power density. High-voltage spikes induced in applications such as solenoid control, solid-state transformer, boost converter, and flyback converter can drive the MOSFET into avalanche mode operation due to high di / dt coupled with parasitic inductance. Avalanche mode operation is characterized by high-power dissipation within the device due to the high voltage and current crossover. This study focuses on the evaluation of two commercially available SiC MOSFETs from different manufacturers, each rated for 1200 V with an ON-state resistance of 80 mΩ, during unclamped inductive switching (UIS) mode operation. To determine device reliability, a decoupled UIS testbed was developed to evaluate the avalanche energy robustness at 22 $ \,^{\circ}$ C and 125 $ \,^{\circ}$ C during two specific conditions: high current and low energy, and low current and high energy. The SiC MOSFETs were evaluated using a load inductance of 1.42, 5.1, 10.5, and 15.8 mH to understand the effect of current and avalanche energy on device failure. To correlate the experimental results with the failure mechanism, estimated junction temperature and static device characteristics are presented; additionally, MOSFETs were decapsulated to examine the failure sites on the semiconductor die.
TL;DR: This study develops a newly designed, patented, bidirectional dc/dc converter (BDC) that interfaces a main energystorage, an auxiliary energy storage, and dc-bus of different voltage levels, for application in hybrid electric vehicle systems.
Abstract: This study develops a newly designed, patented, bidirectional dc/dc converter (BDC) that interfaces a main energy storage (ES1), an auxiliary energy storage (ES2), and dc-bus of different voltage levels, for application in hybrid electric vehicle systems. The proposed converter can operate in a step-up mode (i.e., low-voltage dual-source-powering mode) and a step-down (i.e., high-voltage dc-link energy-regenerating mode), both with bidirectional power flow control. In addition, the model can independently control power flow between any two low-voltage sources (i.e., low-voltage dual-source buck/boost mode). Herein, the circuit configuration, operation, steady state analysis, and closed-loop control of the proposed BDC are discussed according to its three modes of power transfer. Moreover, the simulation and experimental results for a 1-kW prototype system are provided to validate the proposed converter.
TL;DR: In this article, a quadratic boost converter is combined with a voltage multiplier cell and an output filter to offer a high-voltage gain converter with nonpulsating input and output currents.
Abstract: The need of dc–dc switching converters for power supplies with high-voltage gains has increased in the recent years due to new applications in areas as renewable energy systems, transportation, industrial, medical, and others. A quadratic boost converter is a useful topology to obtain a step-up output voltage; however, a major drawback is the presence of a higher voltage stress over the active and passive switches. In this paper, a quadratic boost converter is combined with a voltage multiplier cell and an output filter to offer a high-voltage gain converter with nonpulsating input and output currents. The expressions for the capacitor voltages and inductor currents are given, as well as the corresponding ripples that allow the proper design of the converter. The bilinear switched, nonlinear averaged and linear averaged models are derived such that the dynamical behavior of the converter is analyzed and used to design a control strategy. A step-by-step procedure is given to tune up a current-mode controller. Experimental results are shown from a prototype, which delivers an output voltage of 220 V and an output power of 300 W. Step load changes between 20% and full load are applied to exhibit the robustness of switching regulator.
TL;DR: The design and implementation of high-efficiency magnetics necessary to realize an isolated full bridge dc–dc converter are presented and the experimental demonstration of ultrahigh efficiency in a 2-kW isolated GaN converter is presented.
Abstract: This paper demonstrates the utilization of gallium nitride (GaN) devices to achieve an ultrahigh efficiency in an isolated dc–dc converter. This paper presents the design and implementation of high-efficiency magnetics necessary to realize such an ultrahigh efficiency converter. Synchronous rectification is also implemented to further improve the efficiency. Compared to an equivalent silicon MOSFET, GaN devices have low output charge, very low gate drive losses, and zero reverse recovery losses, this makes GaN devices more suitable for power converters to achieve high efficiency. A complete analytical loss modeling for an isolated full bridge dc–dc converter is discussed in this paper. Furthermore, the experimental demonstration of ultrahigh efficiency in a 2.4-kW isolated GaN converter is presented. Ultrahigh conversion efficiency allows the realization of a very compact dc–dc converter with a very small or no heat sink. The prototype converter has a power density of 7 kW/L and the measured efficiency is above 98.5% over a wide range of output power. The maximum measured efficiency of the converter is 98.8% at 50% of full load.
TL;DR: A bidirectional flyback converter based isolated-port differential power processing (DPP) architecture at the submodule level can distinctly mitigate the energy loss in a PV system, increase output power harvest, and achieve high efficiency under partial shading condition.