The research on DC-DC power converters has been a matter of interest for years since this type of converter can be used in a wide range of applications. The main research is focused on increasing the converter voltage gain while obtaining a good efficiency and reliability. Among the different DC-DC converters, the flyback topology is well-known and widely used. In this paper, a novel high efficiency modified step-up DC-DC flyback converter is presented. The converter is based on a N-stages flyback converter with parallel connected inputs and series-connected outputs. The use of a single main diode and output capacitor reduces the number of passive elements and allows for a more economical implementation compared with interleaved flyback topologies. High efficiency is obtained by including an active snubber circuit, which returns the energy stored in the leakage inductance of the flyback transformers back to the input power supply. A 4.7 kW laboratory prototype is implemented considering four flyback stages with an input voltage of 96 V and an output voltage of 590 V, obtaining an efficiency of 95%. The converter operates in discontinuous current mode then facilitating the output voltage controller design. Experimental results are presented and discussed.

The development of distributed generation, mainly based on renewable energies, requires the design of control strategies to allow the regulation of electrical variables, such as power, voltage (V), and frequency (f), and the coordination of multiple generation units in microgrids or islanded systems. This paper presents a strategy to control the active and reactive power flow in the Point of Common Connection (PCC) of a renewable generation system operating in islanded mode. Voltage Source Converters (VSCs) are connected between individual generation units and the PCC to control the voltage and frequency. The voltage and frequency reference values are obtained from the P–V and Q–f droop characteristics curves, where P and Q are the active and reactive power supplied to the load, respectively. Proportional–Integral (PI) controllers process the voltage and frequency errors and set the reference currents (in the dq frame) to be imposed by each VSC. Simulation results considering high-power solar and wind generation systems are presented to validate the proposed control strategy.

This paper presents a new control strategy using model-based predictive current control (MB-PCC) for a doubly fed induction machine (DFIM) driven by an indirect matrix converter (IMC). This strategy proposes the control of rotor currents, whose references are calculated from active and reactive stator power set points and the dynamic model of the DFIM. The control strategy works well in the four P-Q operating regions of the DFIM. The grid synchronization process is carried out by setting the P-Q power set points to zero. The results presented include the DFIM synchronization procedure as well as the active and reactive power control at variable shaft speed to validate the feasibility of the proposed strategy.