Abstract-This paper presents new step-up dc/dc converter topologies intended for distributed power generation systems. The topologies contain a voltage-fed quasi-Z-source inverter with continuous input current on the primary side, a single-phase isolation transformer, and a voltage doubler rectifier (VDR). To increase the power density of the converter, a three-phase auxiliary ac link (a three-phase inverter and a three-phase isolation transformer) and a three-phase VDR are proposed to be implemented. This paper describes the operation principles of the proposed topologies and analyzes the theoretical and experimental results.

No abstract

No abstract

Shoot-through control methods for qZSI-based dc/dc converters are presented and studied. The major goal was to increase efficiency. A new modulation technique, pulse width modulation (PWM) with shifted shoot-through, is compared with the conventional PWM shoot-through control method. The new method reduces switching frequency of bottom side transistors and inherently features partial soft switching. Previous studies have shown that the biggest drawback of PWM control with shoot-through is unequal switching frequencies of transistors. One solution to that problem could be signal swapping that has been proposed by the authors of this paper. All control methods are first simulated and then experimentally verified on a test prototype.

No abstract

This paper focuses on the galvanically isolated quasi-Z-source dc-dc converter with a novel zero voltage and zero current switching technique. The unique feature of the impedance network lies in combining the buck-boost operation capability with the short-and open-circuit immunity of transistors; at the same time it can perform zero voltage and zero current switching on the primary side. The boundary conduction mode of the current in the second inductor of the quasi-Z-source network was used along with snubber capacitors in the two out of four transistors and a special control algorithm to achieve full zero-switching operation of the inverter. Simulation and experimental results prove the discussed ideas. Possible modifications of the algorithm and future applications are also described. Index Terms-DC-DC power conversion, soft-switching, quasi-Z-source network I. INTRODUCTIONRenewable energy systems have become very popular. As a result, many new types of interface converters from the source to the grid have emerged. In order to extend voltage regulation capability the intermediate boost dc-dc converters are often used. At the same time, the challenges faced in this field are to decrease the cost, size, weight and to increase reliability. All these parameters depend on the converter efficiency, switching frequency of semiconductors, EMI problems, especially in the system where galvanic isolation is required.In order to achieve the tasks above, main efforts of the power electronics research are concentrated on the wide bandgap semiconductors [1], [2] and novel soft-switching converter topologies [3]-[10] in particular. He has over 60 publications and is the holder of several patents. His research interests are in Power Electronics systems. Design of novel topologies, control systems based on a wide range of algorithms, including modeling, design, and simulation. Applied design of power converters and control systems and application, stability investigation.

No abstract

This paper proposes a novel step-up DC/DC converter with galvanic isolation -the quasi-Z-source inverter (qZSI) based DC/DC converter and discusses three different shootthrough PWM control methods suitable for this topology. The proposed converter is meant for applications where the wide range of voltage gain is demanded, e.g. with renewable energy sources (fuel cells, photovoltaic cells), in telecom, aerospace and some other applications. For the verification of theoretical assumptions the converter prototype was assembled and tested. Experimental waveforms of the converter operated with different shoot-through PWM control methods are compared and discussed. Design considerations for converter and different control signal generators are provided. Keywords-DC/DC converter, quasi-Z-source inverter (qZSI), control method, pulse-width modulation (PWM), isolation transformer, gating signal generatorI.