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In case of converters used for power conversion, pulse width modulation is used. These converters use switches which operate in switched mode. The load current flows through the switches during its switching operation. Therefore switches are having high stresses and losses which are directly proportional to the frequency of operation. This also results in high value of dv/dt and di/dt due to EMI. In order overcome these disadvantages, LC circuits are used to provide zero current switching (ZCS) and/or zero viltage switching. This circuit overcomes the problems associated with high switching frequency. These soft switched converters have the advantages of better efficiency, compact; less weight, reduced stresses on components and low electromagnetic interference. The series-parallel resonant converters are the preferred topologies for dc-dc power conversion. This type of resonant converters is designed and simulated using resistive load to analyze their performance. Experimental setup has been done for series parallel resonant converter to prove its application to DC motor. Efficiency is calculated. Switching losses is calculated and comparison is made with the conventional system.

This paper presents a sustainable power storage device for household and everyday needs with the use of lithium-ion batteries. The lack of a portable power source with has always been a problem for various needs be it household or aerospace or defence purposes. The existing technology often compromises in the safety of the device and is suitable only for lower power requirement electronics such as smartphones. This expandable power bank aims to be a higher capacity device to be able to power higher-end electronics such as laptops, television. The implementation of various safety features such as over current, over voltage protection makes it more robust and increases the longevity of the device the power bank can be charged either through either a PV source or a wall point. This paper investigates various types of available technologies for its architecture using software systems. The simulation results of the system and the hardware components which are needed to be used are given clearly with the ratings.

A modified selective harmonic mitigation (SHM) technique for multilevel inverters considering the RMS output voltage magnitude is presented. The harmonic contents in the output voltage of these inverters must satisfy the specified grid code requirement standards. In conventional SHM techniques, the firing angles of the multilevel inverters have been derived by taking into account grid code harmonic reduction standards. When the multi-level inverters are driven with these firing pulses generated, it results in reduction of the magnitude of the inverter output voltage. In order to overcome this issue of output voltage reduction, the modified SHM optimization problem includes another constraint on the RMS output voltage limits, which results in different set of firing angles. This facilitates the use of firing angles, which takes into account the grid code standards of harmonic mitigation without compromising the value of the RMS output voltage of the inverters. The proposal has been simulated and validated in MATLAB Simulink and the experimental results are obtained for a single-phase seven level inverter with Silicon made semiconductor switches. By using the proposed method, output voltage THD (upto 40th harmonics were considered) of 5.9 % was obtained, which is well below the harmonic standards specified by EN 50160.