This work proposes a new non-isolated DC-DC converter with high voltage gain using a three-state switching cell and voltage multiplier stages based on capacitors. The value of the gain can be modified depending on the requirements of the application by means of the number of multiplier stages and the duty cycle. The proposed converter can be employed in renewable energy systems where commonly low input voltages (12 Vdc to 48 Vdc) are involved or in uninterrupted power supply (UPS) systems in order to avoid the necessity of a step-up transformer. One first advantage of the proposed solution is the reduced voltage stress across the active switches that is lower than half of the output voltage, what allows the use of MOSFETs with lower drain-to-source resistance. Moreover, by employing the three-state switching cell, the size of the inductor is reduced because the operating frequency of the inductor is double of the switching frequency. The current share between the active switches allows further reduction of the conduction losses. A prototype was built for an input voltage range of 30-45 V, 400 V output voltage and 250 W output power. The operation was evaluated and the experimental waveforms and experimental efficiency curves as a function of the output power are presented

The concept is presented of converters integrated in such a way as to obtain, in a single conversion stage, the maximum energy extraction from photovoltaic panels, battery charging and discharging dynamic control, and high voltage step-up to the inverter DC bus, also operating with soft-switching capability. Although this idea can be applied to most of the high voltage gain topologies, this presented report is based on structures derived from the half-bridge boost converter. Thus, a 500 W prototype, with input voltage of 24 V and output voltage of 200 V, has been developed with the purpose of obtaining experimental results and validating the proposed concept. High efficiency is achieved, above 92.5%, confirming the expected operation and functionalities necessary for the proposed application.Introduction: The growing use of alternative energy sources, such as photovoltaic panels, wind energy conversion systems and fuel cells, brings new challenges for the power electronic society and industry. In particular, small and distributed generation systems, isolated or grid-connected types, are the future trends for this technology. It is predictable that in the future most small consumers could act as an energy seller to the utility. Then the optimisation of the efficiency, volume, weight, and cost of power converters will be key features regarding the viability of these technologies.In the last few years, photovoltaic panels have been used only in isolated systems, in order to charge battery banks or in pumping systems, and the traditional power converters have been able to achieve maximum power point operation and battery charge control. Nowadays, many systems use an AC power supply and a low voltage inverter associated with a low frequency transformer to provide a sinusoidal voltage waveform with the appropriated voltage level. However, this solution presents high weight and appreciable losses owing to the high currents processed by the inverter and owing to the low frequency transformer. Thus, an additional stage is necessary to step the low level voltage up from the battery bank (12, 24, or 48 V) to the higher voltage level of the inverter DC link (200 or 400 V). As traditional step-up converters are not feasible for providing such high voltage gain, typical solutions use one high frequency isolated stage to achieve the high step-up voltage gain. Recently, non-isolated DC-DC converters with high voltage gain capability were successfully introduced [1, 2]. However, in systems where photovoltaic panels and battery banks are required, two DC-DC stages are still necessary, as shown in Fig. 1a.

The wind energy system presented in this paper uses a permanent magnet generator connected to a threephase semi-controlled rectifier. Although an acceptable THD and power factor result, the proposed converter is simple, cheaper, and robust. Additionally, a single-phase PWM inverter is also employed in the grid connection. The inverter uses a double hysteresis in the control of the current injected in the grid, what implies reduced switching losses. Analysis and partial experimental results are presented for a 5 kW prototype. At the final version of this paper, a more detailed theoretical analysis, simulation results, as well as experimental results at rated power are supposed to be presented.

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A new type of non-isolated step-up converter with high voltage gain is proposed on this work. It is suitable for applications with a high voltage gain between the input and the output stages. In this converter, the output to input voltage ratio, for a given duty cycle, can be raised by adding voltage multiplier stages of capacitors (mc).The theoretical and experimental results it will be present in this paper considering two configurations (mc=2) and (mc=3).An important feature of this converter is the lower blocking voltage across the controlled s w i t c h e s c o m p a r e d t o s i m i l a r c i r c u i t s , w h i c h a l l o w s t h e utilization of low voltage MOSFETs switches.In order to verify the feasibility of the proposed topology, the principle of operation, theoretical analysis, and experimental waveforms are shown for a 1kW prototype.I.

This paper proposes the use of a voltage doubler rectifier as the output stage of an interleaved boost converter with coupled inductors. The obtained voltage gain is twice that of traditional boost converters due to the doubler stage, as coupled inductors provide additional voltage gain, although voltage stress across the switches is not increased. The resulting topology is adequate for battery sourced systems which require low current ripple and high voltage gain e.g. UPS's and audio amplifiers. Additionally, it can be used to obtain symmetrical power supply. Theoretical analysis and experimental results from a 1kW prototype are shown.

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