A High Step-Up Dc-Dc Converter using a Three Winding Coupled Inductor for Photovoltaic to Grid Applications

A dual-switch high step-up DC-DC converter topology is proposed in this paper. The proposed topology uses two power switches, a three-winding coupled inductor (TWCI), and voltage multiplier cells to provide a high voltage gain. Furthermore, the voltage stresses on power semiconductor switches are low, resulting in lower switching and conduction losses. Moreover, the common electrical ground is preserved in this topology, making it a suitable candidate for photovoltaic (PV) to grid systems. The operating modes and steady state analysis of the proposed converter are presented, and a comparative study is carried out to demonstrate advantages of the proposed topology over the existing topologies. Finally, the simulation results of the proposed topology are presented using PLECS software along with the experimental results for a 200 W, 30 V to 400 V laboratory setup

A wide input-voltage range quasi-Z source boost DC-DC converter with high voltage-gain for fuel cell vehicles

A quasi-Z-source Boost DC-DC converter which uses a switched-capacitor is proposed for fuel cell vehicles. The topology can obtain a high voltage gain with a wide input-voltage range, and requires only a low voltage stress across each of the components. The performance of the proposed converter is compared with other converters which use Z-source networks. A scaled-down 400V/400W prototype is developed to validate the proposed technology. The respective variation in the output voltage is avoided when the wide variation in the input voltage happens, due to the PI controller in the voltage loop, and a maximum efficiency of 95.13% is measured

A Model of DC-DC Converter with Switched-Capacitor Structure for Electric Vehicle Applications

In this paper, a DC-DC converter with an innovative topology for automotive applications is proposed. The goal of the presented power converter is the electrical storage system management of an electric vehicle (EV). The presented converter is specifically compliant with a 400 V battery, which represents the high-voltage primary source of the system. This topology is also able to act as a bidirectional power converter, so that in this case, the output section is an active stage, which is able to provide power as, for example, in the case of a low-voltage battery or a supercapacitor. The proposed topology can behave either in step-down or in step-up mode, presenting in both cases a high gain between the input and output voltage. Simulation results concerning the proposed converter, demonstrating the early feasibility of the system, were obtained in a PowerSIM environment and are described in this paper

A DC-DC boost converter with a wide input range and high voltage gain for fuel cell vehicles

In fuel cell vehicles, the output voltage of the fuel cell source is typically much lower than the voltage required by the DC bus and also this output voltage drops significantly as the output current increases. In order to match the output voltage of the fuel cell source to the DC bus voltage, a new DC-DC boost converter with a wide input range and high voltage gain is proposed to act as the required power interface, which reduces voltage stress across the power devices and operates with an acceptable conversion efficiency. A prototype rated at 300W/400V has been developed and the maximum efficiency of the proposed converter was measured as 95.01% at 300W. Experimental results are presented to validate the effectiveness of the proposed converter

High efficiency and high gain non-isolated bidirectional dc-dc converter with soft switching capability

The non-isolated dc-dc power converters are considered as a unique option for flexible voltage control and adaptation in the modern energy conversion systems due to their simple and light configurations. To this date, these converters are primarily investigated to generate high efficiency and high gain with a sustained soft switching capability and a smaller footprint. On that account, this work proposes two effective solutions to address the aforementioned issues. First, a high-efficiency soft switching non-isolated bidirectional dc-dc converter with a simple configuration is proposed. The converter executes the zero voltage zero current switching (ZVZCS) over a wide operating region to ensure high efficiency. For verification, a 150 W experimental prototype is built and tested for soft switching performance by varying the input voltage, switching frequency and the loading. It is observed that the efficiency remains consistently high and has a full-load maximum of 98.2% in the boost mode and 97.5% in the buck mode. The analysis of the Electromagnetic Interference (EMI) performance of the converter also shows the improvement in the noise signature. Second, an improved high gain zero voltage switching (ZVS) nonisolated bidirectional dc-dc converter is proposed. The high gain is realized by using an intermediate energy storage cell with reduced size. Besides, the ZVS is implemented by two integrated auxiliary resonant networks. These networks ensure sustained ZVS operation over the entire duty ratio. A 200 W prototype is built to verify the concept. As a result, a full load efficiency of 97.5% (in boost mode) and 95.5% (in buck mode) is recorded at fs= 30 kHz. Also, these efficiencies are recorded as 97% (boost mode) and 94.5% (buck mode) at fs= 100 kHz. Moreover, it is observed that the efficiency (and so the soft switching) is consistent over the entire gain profile. However, there is a slight additional drop of 1.5% (boost mode) and 1% (buck mode) at extreme duty ratios. Both converters also implement soft switching for auxiliary switches and eliminate the reverse recovery loss

High-Voltage-Gain DC-DC Power Electronic Converters -- New Topologies and Classification

This dissertation proposes two new high-voltage-gain dc-dc converters for integration of renewable energy sources in 380/400V dc distribution systems. The first high-voltage-gain converter is based on a modified Dickson charge pump voltage multiplier circuit. The second high-voltage-gain converter is based on a non-inverting diode-capacitor voltage multiplier cell. Both the proposed converters offer continuous input current and low voltage stress on switches which make them appealing for applications like integration of renewable energy sources. The proposed converters are capable for drawing power from a single source or two sources while having continuous input current in both cases. Theoretical analysis of the operation of the proposed converters and the component stresses are discussed with supporting simulation and hardware results. This dissertation also proposes a family of high-voltage-gain dc-dc converters that are based on a generalized structure. The two stage general structure consists of a two-phase interleaved (TPI) boost stage and a voltage multiplier (VM) stage. The TPI boost stage results in a classification of the family of converters into non-isolated and isolated converters. A few possible VM stages are discussed. The voltage gain derivations of the TPI boost stages and VM stages are presented in detail. An example converter is discussed with supporting hardware results to verify the general structure. The proposed family of converters can be powered using single source or two sources while having continuous input current in both cases. These high voltage gain dc-dc converters are modular and scalable; making them ideal for harnessing energy from various renewable sources offering power at different levels --Abstract, page iv

Design and analysis of a novel multi-input multi-output high voltage DC transformer model

a novel Multi-Input Multi-Output (MIMO) step-up DC transformer for applications in high voltage renewable energy sources is designed and presente

Efficient, High Power Density, Modular Wide Band-gap Based Converters for Medium Voltage Application

Recent advances in semiconductor technology have accelerated developments in medium-voltage direct-current (MVDC) power system transmission and distribution. A DC-DC converter is widely considered to be the most important technology for future DC networks. Wide band-gap (WBG) power devices (i.e. Silicon Carbide (SiC) and Gallium Nitride (GaN) devices) have paved the way for improving the efficiency and power density of power converters by means of higher switching frequencies with lower conduction and switching losses compared to their Silicon (Si) counterparts. However, due to rapid variation of the voltage and current, di/dt and dv/dt, to fully utilize the advantages of the Wide-bandgap semiconductors, more focus is needed to design the printed circuit boards (PCB) in terms of minimizing the parasitic components, which impacts efficiency. The aim of this dissertation is to study the technical challenges associated with the implementation of WBG devices and propose different power converter topologies for MVDC applications. Ship power system with MVDC distribution is attracting widespread interest due to higher reliability and reduced fuel consumption. Also, since the charging time is a barrier for adopting the electric vehicles, increasing the voltage level of the dc bus to achieve the fast charging is considered to be the most important solution to address this concern. Moreover, raising the voltage level reduces the size and cost of cables in the car. Employing MVDC system in the power grid offers secure, flexible and efficient power flow. It is shown that to reach optimal performance in terms of low package inductance and high slew rate of switches, designing a PCB with low common source inductance, power loop inductance, and gate-driver loop are essential. Compared with traditional power converters, the proposed circuits can reduce the voltage stress on switches and diodes, as well as the input current ripple. A lower voltage stress allows the designer to employ the switches and diodes with lower on-resistance RDS(ON) and forward voltage drop, respectively. Consequently, more efficient power conversion system can be achieved. Moreover, the proposed converters offer a high voltage gain that helps the power switches with smaller duty-cycle, which leads to lower current and voltage stress across them. To verify the proposed concept and prove the correctness of the theoretical analysis, the laboratory prototype of the converters using WBG devices were implemented. The proposed converters can provide energy conversion with an efficiency of 97% feeding the nominal load, which is 2% more than the efficiency of the-state-of-the-art converters. Besides the efficiency, shrinking the current ripple leads to 50% size reduction of the input filter inductors

Conversores CC-CC não-isolados com alta taxa de conversão baseados no empilhamento de topologias convencionais

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2020.Esta tese tem como objetivo contribuir no estudo de novas topologias de conversores CC-CC não-isolados abaixadores com alta taxa de conversão. As topologias propostas são geradas a partir do empilhamento de estruturas convencionais e podem ser empregadas em aplicações em que elevados níveis de tensão estão envolvidos. As principais características das topologias propostas são a possibilidade de modularidade da estrutura, balanceamento natural das tensões nos capacitores e reduzidos esforços de tensão nos dispositivos semicondutores, permitindo o uso de interruptores e diodos da baixa tensão. Os conversores propostos também podem ser utilizadas como barramento CC proporcionando um ou mais níveis de tensão de saída, onde diferentes cargas podem ser conectadas em um ou mais capacitores da pilha. Dois tipos de estruturas são estudadas neste trabalho: conversores CC-CC baseados no empilhamento de topologias não-isoladas convencionais e conversores CC-CC baseados no empilhamento de topologias isoladas. Uma análise teórica generalizada com ganho estático, esforços de tensão e corrente nos principais componentes, análise do fluxo de potência e rendimento é apresentada para todas as topologias propostas. Com o objetivo de avaliar o desempenho e validar a análise teórica generalizada, protótipos para os dois tipos de estruturas com 250 W e 4 kW de potência de saída e tensão de entrada de 1200 V foram construídos e testados experimentalmente. Os resultados experimentais obtidos corroboram com a análise teórica e demonstram a viabilidade dos conversores propostos.Abstract: This thesis aims to contribute to the study of new topologies of step-down nonisolated dc-dc converters with high conversion ratio. The proposed topologies are generatedfrom the stacking of conventional structures and they can be employed in applicationswhere high levels of voltage are involved. The main features of the proposed topologies arethe possibility of modularity, natural voltage balance across the capacitors and reducedvoltage stresses on the semiconductor devices, allowing the use of low voltage switchesand diodes. The proposed converters can also be used as dc bus, providing one or severaloutput voltage levels, where different loads can be connected to one or more capacitorsof the stack. Two types of structures are studied in this work: dc-dc converters based onstacking of conventional non-isolated topologies and dc-dc converters based on stackingof conventional isolated topologies. A generalized theoretical analysis with static gain,voltage and current stresses on the main components, power flow analysis and efficiency ispresented for all the proposed topologies. In order to evaluate performance and validatethe theoretical analysis, prototypes for the two types of structures with 250 W and 4kW of output power and 1200 V input voltage were built and tested experimentally. Theexperimental results obtained corroborate the theoretical analysis and they demonstratethe feasibility of the proposed converters