Renewable power systems often experience big changes in generating output due to fluctuations of energy resources. A boost converter is added to step up the dc voltage when the energy resources are at a weak point. When a very high boost gain is demanded, it experiences serious reverse-recovery problemsdue to large duty cycles. This paper proposes a coupled inductor,by employing a coupled inductor in the circuit and proper adjustment of shoot-through state of a three-phase inverter the converter can realize higher boost gain and a stable ac output voltsge. Finally, the simulation using matlab/simulink results are presented in the paper.

KEY WORD: Boost inverter, coupled inductor, shoot-through zero state

The applications of power electronic converters has increased widely in different sectors like industrial, commercial, residential, aerospace due to rapid development in power semiconductor devices. Due to presence of power semiconductor devices the current drawn from line is distorted resulting in a high Total Harmonic Distortion (THD) and low Power Factor (PF). So there is a need to improve Power Factor and reduce line current harmonics. This paper aims to develop a circuit for PFC using a pi and fuzzy controlled two phase interleaved boost converter. The PFC strategy uses the interleaving scheme with pi and fuzzy controllers for reducing input current harmonics. The developed circuit model is simulated by using matlab software. The simulation result will show that there is a significant decrease in THD and improvement in Power Factor

KEY WORD: PFC Boost converter, interleaving scheme, pi and fuzzy system.

This paper proposes simulation modeling and control of hybrid ac/dc micro grid. The micro grid concept introduces the reduction of multiple reverse conversions in an individual AC or DC grid and also facilitates connections to variable renewable AC and DC sources and loads to power systems. The interconnection of DGs to the utility/grid through power electronic converters has risen concerned about safe operation and protection of equipment's. The performance of proposed hybrid AC/DC micro grid system is analyzed in a grid-tied or autonomous mode. Here photovoltaic system, wind turbine generator and battery are used for the development of microgrid. Also control mechanisms are implemented for the converters for smooth power transfer and properly coordinate the AC sub-grid to DC sub-grid. The system is simulated in the MATLAB/ SIMULINK environment

KEY WORD: Energy management, grid control, grid operation, hybrid micro grid, PV system, wind power generation.

The resonant power conversion having many advantages over conventionally adopted pulse width modulation that includes a high efficiency, low electromagnetic interference, small volume, low switching losses, and light weight of components due to a high switching frequency, and low reverse recovery losses in diodes owing to a low di/dt at switching instant. This paper presents the doubly loaded resonant power converter for dc to dc conversion. The proposed circuit consists of half bridge inverter, Double LCL filter and diode bridge rectifier. The output is filtered by a low pass filter. A MATLAB based simulation circuit is designed and verified for the different loads. The proposed novel loaded resonant circuit reaches up to 92% efficiency. The circuit result performs a satisfactory performance of the topology. The loaded resonant power conversion circuit is used in telecom power supplies, solar energy generation systems, UPS, battery charging system, switching circuits and power electronic circuits.

KEY WORD: Zero voltage switching, Zero current switching and resonant converter.

Pulse width modulation is the process of modifying the width of the pulses in a pulse train in direct proportion to a small control. In the PWM technique reference is commonly taken depended on the output waveform. Depending on the frequency there are two types of switching frequencies; constant switching frequency and variable switching frequency. Compared with constant switching frequency pulse width modulation method, variable switching frequency PWM can benefit more because of the extra freedom. Two methods are discussed in this concept. The first method is designed to arrange the current ripple peak value within a certain value and can reduce the equivalent switching frequency and electromagnetic interference (EMI) noise, the second method is designed to keep ripple current RMS value constant and reduce the EMI noise. Simulation results should be validating by showing the variable switching frequency applied with induction motor drive could improve the performance of EMI and efficiency of converter by using Mat lab / Simulink

KEY WORD: current ripple, three phase inverter, pulse width modulation, variable switching frequency, induction motor.

Static synchronous compensators (STATCOMs) provide a power-electronics-based means of embedded control of transmission-line voltage and power flows. The integration of multilevel inverter to a STATCOM can extend traditional STATCOM capabilities to two way power flow control. This paper gives an overview of multilevel dual converter based STATCOMs with a focus on achieving minimum harmonic distortion and reasonable power quality improvement. The dual converter consists of two converters with different voltages to supply/absorb reactive power to/from the grid. The controller used in the STATCOMs can balance individual dc capacitor voltages when H-bridges run with different switching patterns and have parameter variations[1]. Reduced component count, simpler layout for switches, and smaller dc-link capacitor values are the attractive features of the proposed topology over the cascaded multilevel converters[2]. In extension to this the proposed system with STATCOM is designed with nine-level diode clamped multilevel inverter with sinusoidal PWM.

KEY WORD: Diode-clamped inverter, cascaded inverters, voltage source converter(VSC), Pulse width modulation (PWM), cascaded Multi cell inverter, static compensator (STATCOM)