This paper proposes a low voltage (400 Vdc) distributed renewable energy fed DC microgrid structure for a residential system, which uses DC voltage for the electronic appliances. The distributed energy sources—solar photovoltaic (PV) and wind energy are considered as input sources. The output power from these sources is stochastic in nature. An efficient energy management and switching circuit is designed to control the power flow from the sources with a high gain DC‐DC converter as the main component. The output power regulation is achieved by means of controlling duty ratios of the switches in the proposed high gain converter through PI controller. The control algorithm effectively converts the unregulated DC power from the solar PV and wind into regulated DC for driving a DC load connected in DC‐microgrid. The energy management and switching circuits account for seamless operation of the DC microgrid under various modes when one or all the sources and loads are connected directly at the DC grid link. The designed energy management and switching circuit also ensures the power balancing in the proposed system. The proposed DC microgrid structure is simulated using MATLAB Simulink. The performance of the proposed high gain converter for the DC grid link voltage regulation is analyzed under source power variation and dynamic changes in load for various operating conditions. The proposed DC microgrid structure is validated using simulation results.

Power factor corrected AC-DC converter topologies have been of research interest for DC power supplies. The main goal of this work is to improve power quality at the supply side and maintain constant DC voltage at the output side by designing a Modified Bridge Less Positive Output Luo (MBLPOL) power factor correction (PFC) converter. Discontinuous conduction mode is also possible for input PFC with a small filter at the source side. In order to regulate the DC load voltage for various loads and supply voltage conditions, a feedback control circuit with a single voltage sensor is proposed for the PFC converter. A prototype of 100 W, 48 V, AC-DC MBLPOL converter is designed and tested. Proper design of controller for the converter guarantees the excellent performance and the same is validated with the help of simulation and hardware results. The proposed MBLPOL converter is tested for DC load voltage regulation for various load power and supply voltage variations. The experimental study shows supply current total harmonic distortion of 1.24% at rated load while maintaining unity power factor.

Summary In DC microgrids, power converters are essential for interconnecting and controlling power flow from the renewable sources such as solar PV, wind, fuel cell, and so on with the DC grid link. A lot of DC‐DC power converters available in the literatures are used to boost the low voltage from the renewable sources to the high voltage and also to track the maximum power from these sources. To boost the output voltage, high gain converters are required. To increase the static gain of the converters, many techniques such as using voltage lift, switched capacitor, coupled inductor, and so on are used. This paper presents a novel high gain DC‐DC converter that does not use the above techniques for voltage boosting. An inductive reactive element is added in series with a switch to boost the voltage gain. This inductor is connected in parallel with the source voltage when the switches are in ON position and in series with the source when the switches are in OFF position. The proposed converter is designed to produce the output voltage of 380 V for the input of 48 V. The converter is designed to handle the power of 1 kW. With the use of the voltage boosting element, a maximum voltage gain of 28 is achieved and the efficiency of converter is about 91.9%. The performance of the proposed converter is simulated and analyzed for various conditions such as variation in input voltage, reference voltage, and load power and also for motor loads. The experimental prototype model is also built and the hardware results are shown in this paper to validate the simulation results.

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Stringent environmental regulations and increasing oil prices showcase the need for renewable energy sources like solar in marine transportation. The application of solar energy in electric propulsion systems is growing tremendously. Power electronics-based inverters help in harvesting direct current (DC) power into alternating current (AC) power. A multilevel inverter (MLI) is a popular power electronic converter producing the desired output voltage from several DC input voltage sources like batteries, supercapacitors, and solar panels. An MLI consists of several switches whose action results in severe harmonic issues. Specific harmonic elimination in MLI is a challenging job and is resolved conventionally by the Newton-Raphson method. However, nowadays, soft computing techniques are used to solve nonlinear equations optimally. In this manuscript, minimization of total harmonic distortion in MLI has been taken as an optimization problem and is solved using teaching-learning‐based optimization (TLBO). The TLBO algorithm is applied to compute the optimum switching angles for MLI to produce the required fundamental output voltage with less harmonic distortion. As it does not require any algorithm-specific parameters, TLBO is an effective method to obtain optimum MLI solutions. A 21-level symmetric MLI is simulated and is used to evaluate the performance of the TLBO algorithm. The simulation results are validated using an experimental model of proposed MLI with a Xilinx Spartan-SA field programmable gate array‐based controller. This research outcome bears testimony to TLBO optimization's efficiency in improving the quality of the power generated in ships using renewable sources.

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This paper presents the improved single phase AC-DC super lift Luo converter for enhancing quality of power by mitigating the issues. The proposed converter is used for output voltage control, power factor improvement and reduced source current harmonics at supply side. The main intention of this work is to design appropriate closed loop controllers for this AC-DC super lift Luo converter to achieve unity power factor in the source end. The designed control system comprises of two control loops, voltage control in outer loop and the current controller is devised in the inner loop. Fuzzy controller is used for current controller whereas PI controller as voltage controller. In the MATLAB/SIMULINK platform, simulation of the proposed AC-DC super lift Luo converter is done. It is clear from the simulation results that PI integrated fuzzy controller for voltage and control is proven to be better than classical PI with hysteresis controllers. The proposed system is able to achieve high input power factor along with supply current harmonic distortions of less than 5%.