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Uninterruptible power supplies (UPSs) are widely used to deliver reliable and high quality power to critical loads under all grid conditions. This paper proposes a high-frequency isolated online UPS system for low power applications. The proposed UPS consists of a single-stage AC-DC converter, boost DC-DC converter, and an inverter. The single-stage AC-DC converter provides galvanic isolation, input power factor correction, and continuous conduction of both input and output current. The low battery bank voltage is stepped up to high dc-link voltage by employing a high voltage gain boost converter, thus allows the reduction of battery bank to only 24 V parallel connected batteries. Operating batteries in parallel improves the battery performance and resolves the issues related to conventional battery banks that arrange the batteries in series combination. The inverter provides regulated output voltage to the load. A new cascaded slide mode (SM) and proportional-resonant (PR) control for the inverter has been proposed, which regulates the output voltage for both linear and non-linear loads. The controller shows excellent performance during load transients and step changes. Besides, the controller for boost converter and AC-DC converter is presented. Operating principle and experimental results of 1 kVA laboratory setup have been presented for the validation of proposed system. [ABSTRACT FROM AUTHOR]

In this paper, PSO (Particle Swarm Optimization) based technique is proposed to derive optimized switching angles that minimizes the THD (Total Harmonic Distortion) and reduces the effect of selected low order non-triple harmonics from the output of the multilevel inverter. Conventional harmonic elimination techniques have plenty of limitations, and other heuristic techniques also not provide the satisfactory results. In this paper, single phase symmetrical cascaded H-Bridge 11-Level multilevel inverter is considered, and proposed algorithm is utilized to obtain the optimized switching angles that reduced the effect of 5th, 7th, 11th and 13th non-triplen harmonics from the output voltage of the multilevel inverter. A simulation result indicates that this technique outperforms other methods in terms of minimizing THD and provides high-quality output voltage waveform. [ABSTRACT FROM AUTHOR]

Summary: Multilevel inverters have been the vital component for the power electronic systems and have been researched extensively to further enhance their performances in terms of topology and their control. In this paper, a new bidirectional single‐phase multilevel inverter module has been proposed with a reduced number of switches along with lower voltage stresses. The proposed module generates 17 levels at the output with 10 unidirectional switches along with four dc voltage sources with two varieties of dc voltage sources. Moreover, for a higher number of levels, the cascade connection of several modules has been discussed in this paper with three different methods for the selection of dc voltage sources. The proposed module has been compared with several similar topologies, which set the benchmark of the proposed one. The operation and performance of the proposed module have been validated through several simulation and experimental results with different types of load considering a change of modulation index. [ABSTRACT FROM AUTHOR]