Focus is on implementation possibilities of surfacemount device (SMD) to be used in high power applications. SMD capacitors reduce the size and dimensions of a power circuit and increase the flexibility of placement of other components. Ceramic and electrolytic capacitors are compared by means of voltage ripple, volume, labour-intensity and impedance. A 1 kW experimental setup of a quasi-Z-Source inverter (qZSI) based converter was built to compare SMD capacitor performance in the quasi-Z-source (qZS) network.
Study of Simple MPPT Converter Topologies for Grid Integration of Photovoltaic Systems
This paper presents a study of two simple MPPT converter topologies for grid integration of photovoltaic (PV) systems. A general description and a steady state analysis of the discussed converters are presented. Main operating modes of the converters are explained. Calculations of main circuit element parameters are provided.
Experimental setups of the MPPT converters with the power of 800 W were developed and verified by means of main operation waveforms. Also, experimental and theoretical boost properties of the studied topologies are compared.
Finally, the integration possibilities of the presented MPPT converters with a grid side inverter are discussed and verified by simulations.
Dmitri Vinnikov, Oleksandr Husev and Indrek Roasto
Lossless Dynamic Models of the Quasi-Z-Source Converter Family
This paper is devoted to the quasi-Z-source (qZS) converter family. Recently, the qZS-converters have attracted attention because of their specific properties of voltage boost and buck functions with a single switching stage, which could be especially beneficial in renewable energy applications. As main representatives of the qZS-converter family, the traditional quasi-Z-source inverter as well as two novel extended boost quasi-Z-source inverters are discussed. Lossless dynamic models of these topologies are presented and analyzed.
Analysis and Design of 3.3 kV IGBT Based Three-Level DC/DC Converter with High-Frequency Isolation and Current Doubler Rectifier
The paper presents the findings of a R&D project connected to the development of auxiliary power supply (APS) for the high-voltage DC-fed rolling stock applications. The aim was to design a new-generation power converter utilizing high-voltage IGBT modules, which can outpace the predecessors in terms of power density, i.e. to provide more power for smaller volumetric space. The topology proposed is 3.3 kV IGBT-based three-level neutral point clamped (NPC) half-bridge with high-frequency isolation transformer and current doubler rectifier that fulfils all the targets imposed by the designers. Despite an increased component count the proposed converter is very simple in design and operation. The paper provides an overview of the design with several recommendations and guidelines. Moreover, the simulation and experimental results are discussed and the performance evaluation of the proposed converter is presented.
Thermal management is a crucial step in the design of power electronic applications, especially railroad traction and automotive systems. Mass/size parameters, robustness and reliability of the power electronic system greatly depend on the cooling system type and performance. This paper presents an approximate parameter estimation of the thermal management system required as well as different commercially available cooling solutions. Advantages and drawbacks of different designs ranging from simple passive heatsinks to complex evaporative systems are discussed.
Anna Andrijanovitsh, Ingars Steiks, Janis Zakis and Dmitri Vinnikov
Analysis of State-of-the-Art Converter Topologies for Interfacing of Hydrogen Buffer with Renewable Energy Systems
This paper compares state-of-the-art DC/DC converter topologies for electrolyzer and fuel cell applications in renewable energy systems (RES). The main components of the hydrogen-based energy storage system should be connected to the DC-bus of a RES via separate interface converters: the electrolyzer is interfaced by the step-down DC/DC converter, while the fuel cell is connected through the step-up DC/DC converter. Because of the high input and output voltage differences the topologies with a high-frequency voltage matching transformer are analyzed. The inverter and rectifier sides of the discussed DC/DC converters presented in schemes are analyzed in detail.
Janis Zakis, Dmitri Vinnikov, Indrek Roasto and Tanel Jalakas
Practical Design Guidelines of qZSI Based Step-Up DC/DC Converter
This paper presents some design guidelines for a new voltage fed step-up DC/DC isolated converter. The most significant advantage of proposed converter is voltage buck-boost operation on single stage. The most promising application for proposed converter is in the field of distributed power generation e.g. fuel cells or photovoltaic.
The most sensitive issues - such as power losses caused by high currents in the input side of converter and high transient overvoltages across the inverter bridge caused by stray inductances were discussed and solved. The proposals and recommendations to overcome these issues are given in the paper. The Selection and design guidelines of converter elements are proposed and explained.
The prototype of proposed converter was built and experimentally tested. Some results are presented and evaluated.
Andrei Blinov, Tanel Jalakas, Dmitri Vinnikov and Kuno Janson
Switch-Off Behaviour of 6.5 kV IGBT Modules in Two-Level Voltage Source Inverter
This paper presents an analysis of the switch-off process of 6.5 kV/200 A IGBT modules in a two-level half-bridge voltage source inverter. During experiments, it was stated that real switching process is far from ideal switch-off since parasitic inductance and capacitance in the circuit cause voltage spikes and high frequency oscillations during transition processes. Operation states of the inverter are described and analyzed. Experimental and simulation results are compared, the main transients are analyzed and mathematically expressed and possible problems and solutions are discussed.
Silver Ott, Indrek Roasto, Dmitri Vinnikov and Tõnu Lehtla
Analytical and Experimental Investigation of Neutral Point Clamped Quasi-Impedance-Source Inverter
In this paper a new modification of a three-level neutral-point-clamped inverter is presented. The proposed topology combines the advantages of the three-level neutral-point-clamped full-bridge inverter with those of the quasi-impedance-source inverter. The neutral-point-clamped quasi-impedance-source inverter is especially suitable for renewable energy sources.
The steady-state analysis of a neutral-point-clamped quasi-impedance-source inverter in the continuous conduction mode is presented. The presented models as well as deduced equations are verified by an experimental prototype.
Carlos Roncero-Clemente, Enrique Romero-Cadaval, Oleksandr Husev and Dmitri Vinnikov
In this paper several modulation techniques for a three-level neutral-point-clamped quasi impedance source inverter are proposed and discussed. Mathematical descriptions with simulation results are presented for each modulation technique. Their advantages and disadvantages are shown and guidelines for further improvement are provided.