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A novel start-up method for an isolated full-bridge boost converter with modified phase-shift technique, for RES and automotive applications is proposed. In order to avoid the high inrush currents, the converter is operated in flyback mode at start-up. For precharging the output capacitor no auxiliary circuits or modified switching strategy is necessary. All the power switches of the isolated boost converter are soft switched (ZVS or ZCS), for the whole duty cycle. One single control circuit is used for control, protection and start-up. The voltage-fed control circuit is modified to be applied to the current-fed full-bridge DC-DC converter.

The purpose of this article is to design electromagnetic model for a three phase induction motor premium efficiency (IE3), rated power of 7.5 kW, 1000 rpm single layer windings, designed and produced as prototype by the company Electroprecizia Electrical Motors located in the county of Brasov, Romania.

This paper presents a new soft-switched ZVT DC-DC boost converter with auxiliary transistor and optimized gate drive circuit. This type of converter suits very well applications like automated battery chargers or PFC-Power Factor Correction converters. A conventional PWM controller is used for the ZVS boost converter control. Because the power semiconductor devices voltage and current stresses are similar to that of the regular hard commutated boost converters, the application range is very large.

In this paper an optimized gate drive circuit suitable for two different topologies of ZVT cells is introduced. The correct switching times of the main and auxiliary switches are obtained by monitoring the drain to source voltage of the main transistor and the appropriate gate drive circuit is designed and implemented. In addition, a new interleaved ZVT DC-DC boost converter with coupled inductors is proposed. To verify experimentally the viability of the circuits mentioned above, a laboratory prototype for a two stage interleaved ZVT boost converter has been designed, executed and tested.

Wind pumped storage systems are becoming more and more attractive in the context of higher quantities of wind power to be absorbed by the grid, power system stability, load balancing and frequency control. The power losses of a pump drive inverter system are evaluated considering two different topologies: 2L VSC and respectively 3L NPC VSC starting from 2.2 kW up to 1.85 MW power levels. The analyze is based on practical application considering the standard LV and MV of the induction machine supply RMS voltages and the latest IGBT 3, IGBT 4 (trench technology) and the press-pack IGBT technology for the semiconductor switches.

The purpose of the paper is analyzing the possibilities of improving the efficiency of a 2 kW wind pump storage system at low wind conditions. Two possible solutions are considered for the converter supplying the induction motor pump system: two-level and respectively three-level NPC inverter. Inverter total power losses are computed based on models proposed in the paper, considering a very low wind speed. Space vector pulse width modulation technique is used in both cases. Trench IGBT modules of 1200 V, respectively 600 V are considered as switches and 600 V SIC diode as clamping diode for the three-level NPC inverter.

Energy storage devices and solutions are required for power quality and balance within wind systems. In the context of rapidly expanding of distributed energy sources, the wind energy converters are in the center of interest. In this case, the direct dependence of the power generation capability for a given wind speed represents a major problem of wind energy conversion with regard to large-scale network integration. This paper proposes an overall solution which consists of a wind plant with a Smart Storage Modular System (SSMS) where the wind source -as stochastic one- is coupled over a dc bus with three storage modules and a smart grid interface. The investigated system consists of fours modules: a) the stochastic module (variable wind turbine with PMSG and ac/dc + bust converters), b) the short term storage module (flywheel with power electronic converter), c) the medium/long term module (Vanadium Redox Flow Battery with power electronic converter) and d) the medium term module (Lead Acid Battery). All of modules are interfaced with the network and insulated loads by a grid interface module (power electronic converter, filter and transformer). To the related SSMS, are accomplished computer simulations. In order to validate them, laboratory tests are also presented.