Jakub Dawidziuk

The demand for energy in the world is growing, and the requirements for the efficiency of energy-saving technologies used in renewable energy sources, especially prominent in terms of power electronics, are also increasing. In many renewable energy applications, high-efficiency, high-power DC/DC converters are necessary as an interface between various low-voltage sources and higher output voltage loads, e.g. in photovoltaics. The article presents a comprehensive study on reducing power losses in electric energy conversion in modified isolated and non-isolated DC/DC boost converters powered by low-voltage energy sources. The main desirable features, such as high energy efficiency, high conversion ratio, and low stress on the switches and diodes, were compared and further experimentally validated. The experimental evaluation indicates that the highest efficiency of 96.7%, with a conversion ratio of more than 10, was achieved in the interleaved boost-flyback DC/DC converter. Other investigated systems, namely non-isolated push-pull-boost converters, isolated half-bridge boost, and partially parallel boost converters, achieved slightly lower efficiency. Simultaneously, using the suggested topology, the passive component count was reduced. Furthermore, better utilization of switches and a higher conversion ratio are provided, as well as a possibility of working at a lower duty cycle compared to other step-up converter topologies. All in all, the proposed and studied converters exhibit certain advantages over other state-of-theart solutions and thus can be competitively and effectively employed in modern low-voltage DC/DC applications such as photovoltaics.

The purpose of this paper is to propose a model of a novel quasi-resonant boost converter with a tapped inductor. This converter combines the advantages of zero voltage quasi-resonant techniques and different conduction modes with the possibility of obtaining a high voltage conversion ratio by using a tapped inductor, which results in high converter efficiency and soft switching in the whole output power range. The paper contains an analysis of converter operation, a determination of voltage conversion ratio and the maximum voltage across power semiconductor switches as well as a discussion of control methods in discontinuous, critical, and continuous conduction modes. In order to verify the novelty of the proposed converter, a laboratory prototype of 300 W power was built. The highest efficiency η = 94.7% was measured with the output power Po = 260 W and the input voltage Vin = 50 V. The lowest efficiency of 90.7% was obtained for the input voltage Vin = 30 V and the output power Po = 75 W. The model was tested at input voltages (30–50) V, output voltage 380 V and maximum switching frequency 100 kHz.

This paper presents a dual inductor-fed boost converter with an auxiliary transformer and voltage doubler for sustainable energy power converters. The new topology integrates a two-phase boost converter and a dual inductor-fed boost converter. The energy stored and transferred by both inductors can attain a wide input-voltage and load range which uses a constant switching frequency, by controlling the time duration of the simultaneous conduction of the two switches. Among other current-fed type boost converters the presented topology is attractive due to the high voltage conversion ratio, less stress on the components and less switch conduction loss. To verify the feasibility of this topology, the principles of operation, theoretical analysis, and experimental waveforms are presented for a 1 kW prototype.

Review and comparison of high efficiency high power boost DC/DC converters for photovoltaic applications: Recent environmental issues have accelerated the use of more efficient and energy saving technologies in renewable energy systems. High power high efficiency boost DC/DC converters for the use in photovoltaic, fuel cell systems are discussed in this paper from the viewpoint of power losses and efficiency. State of the art converters with switching frequency within the range of 25 kHz with IGBTs to 100 kHz with power MOSFETs and the highest efficiency close to 98%, depending on the load conditions, is considered. A comparison and discussion of the highest efficiency high power DC/DC boost converters is also presented in this paper.