Faculty Publications
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Item Investigation on cascade multilevel inverter with symmetric, asymmetric, hybrid and multi-cell configurations(Ain Shams University editor@eng.asu.edu.eg, 2017) Yellasiri, Y.; Venkataramanaiah, J.; Panda, A.K.; Dhanamjayulu, C.; Pakala, P.In recent past, numerous multilevel architectures came into existence. In this background, cascaded multilevel inverter (CMLI) is the promising structure. This type of multilevel inverters synthesizes a medium voltage output based on a series connection of power cells which use standard low-voltage component configurations. This characteristic allows one to achieve high-quality output voltage and current waveforms. However, when the number of levels increases switching components and the count of dc sources are also increased. This issue became a key motivation for the present paper. The present paper is devoted to investigate different types of CMLI which use less number of switching components and dc sources and finally proposed a new version of Multi-cell based CMLI. In order to verify the proposed topology, MATLAB – simulations and hardware verifications are carried out and results are presented. © 2016 Ain Shams UniversityItem Development of a New Hybrid Multilevel Inverter Using Modified Carrier SPWM Switching Strategy(Institute of Electrical and Electronics Engineers Inc., 2018) Venkataramanaiah, J.; Yellasiri, Y.; Panda, A.K.This letter presents a single-phase cascaded transformer based multilevel inverter with a modified carrier-based level shift sinusoidal pulse width modulation (LS-SPWM) technique. The developed topology has two bridges with individual low frequency transformers. The bridges can generate quasi-square waveform and pulse width modulated waveform independently and energized the two transformers whose secondary terminals are cascaded to attain 19-level output voltage waveform across the load. The anticipated configuration has the least number of components to reduce the cost and enhance the reliability of the converter for medium power applications with inbuilt isolation. Furthermore, this letter presents the most common LS-SPWM technique with a new carrier to enhance the fundamental magnitude and shifts the dominant harmonics into three times of the traditional strategy for the same modulation indices. The performance of the proposed topology is validated with experimental results. © 1986-2012 IEEE.Item Design and development of a novel 19-level inverter using an effective fundamental switching strategy(Institute of Electrical and Electronics Engineers Inc., 2018) Venkataramanaiah, J.; Yellasiri, Y.; Panda, A.K.This paper presents a single-phase 19-level inverter with fewer switching components, leading to reducing the cost and enhancing reliability for renewable applications. The anticipated multilevel inverter has two bridges that generate quasi-square and seven-level uneven waveforms with equal magnitude steps. Two voltage waveforms are cascaded at secondary side of transformers to create the 19-level output voltage waveform. Furthermore, to find the appropriate switching instants of the proposed configuration, a new fundamental switching method called the fundamental sine quantized switching technique is presented. In fact, it has the capacity to provide the N number of switching instants with less computational efforts, and attain optimized total harmonic distortion in the output voltage. Finally, performance of the proposed topology is validated with simulations and a hardware setup. © 2013 IEEE.Item A Fuzzy Logic Based Switching Methodology for a Cascaded H-Bridge Multi-Level Inverter(Institute of Electrical and Electronics Engineers Inc., 2019) Azeem, H.; Yellasiri, Y.; Jammala, V.; Shiva Naik, B.S.; Panda, A.K.In this letter, an unusual switching technique is implemented using a fuzzy logic approach. The proposed technique simplifies the conventional method by eliminating the traditional logic-gate design. The fuzzy logic pulse generator acts as a lookup table as well as a pulse generator. On the basis of the modulation index as input, controlled membership functions (MFs) and rules of the fuzzy logic controller open various possibilities of producing pulses directly. The proposed technique is evaluated on the cascaded multi-level inverter with symmetric and asymmetric operations using selective harmonic elimination pulsewidth modulation. MFs are designed on the basis of pre-calculated firing conditions for different modulation index values. Hardware verification is carried out to support the proposed switching technique. © 1986-2012 IEEE.Item Experimental verification of a hybrid multilevel inverter with voltage-boosting ability(John Wiley and Sons Ltd vgorayska@wiley.com Southern Gate Chichester, West Sussex PO19 8SQ, 2020) Shiva Naik, B.; Yellasiri, Y.; Venkataramanaiah, J.A new nine-level natural-balanced boost hybrid multilevel inverter (BH-MLI) is proposed in this paper. Each phase of the proposed BH-MLI is designed with only 11 semiconductor switches and two electrolytic capacitors. Here, the capacitor voltages are balanced by utilizing the series-parallel and natural balancing techniques effectively. Furthermore, the proposed circuit eradicates the multiple DC sources by introducing a single DC link for single- and three-phase applications. The proposed topology can be easily extendible to obtain higher level output voltage waveform due to its modular-switched capacitor cells (SCCs). Besides, the higher voltage level generation does not pose high-voltage stress on any of the topology components, as the blocking voltage of all devices within the source voltage magnitude. Further, a quantitative comparison is conducted among the state-of-art switched-capacitor multilevel inverter (SC-MLIs) to highlight the superiority of the proposed configuration. Finally, the performance of the proposed BH-MLI is experimentally validated with phase disposition-pulse width modulation (PD-PWM) and round control method at different modulation indices, load conditions. © 2020 John Wiley & Sons, Ltd.Item Development of cascaded multilevel inverter based active power filter with reduced transformers(China Power Supply Society, 2020) Nageswar Rao, B.N.; Yellasiri, Y.; Panda, A.K.; Shiva Naik, B.S.; Jammala, V.Active power filter is a power electronic converter used for improving the quality of supply by eliminating the effect of harmonics due to non-linear loads. This paper recommends a concept for shunt active power filter (SAPF) using a single power source fed to a cascaded multilevel inverter (CMI) with 3-? transformers. Apart from traditional transformer based topologies, the required number of transformers are substantially reduced, resulting in less space requirement, which leads to low cost and simple control system. The proposed CMI based SAPF has a capacity to compensate for contaminated load with high harmonic and a low power factor. The effective id ? iq theory is used to calculate compensation currents. DC link voltage regulator analyzed through delay time and controller gain. The tasks of the controller in the SAPF can perform all necessary actions for correct operation in SAPF. A wide range of computer simulation results demonstrated and validated the results with the prototype experimental setup. © 2021 All rights reserved.Item A Hybrid Nine-Level Inverter Topology with Boosting Capability and Reduced Component Count(Institute of Electrical and Electronics Engineers Inc., 2021) Shiva Naik, B.S.; Yellasiri, Y.; Venkataramanaiah, J.; Panda, A.K.Nowadays, output voltage boosting gain property along with curtailment in the circuit voltage stress, and component count are considered as the essential topological features for the new multilevel inverter (MLI) circuits. Recognizing the above, a hybrid nine-level inverter topology (HNIT) for DC-AC conversion is proposed in this brief. Each phase of the HNIT is designed with only eight semiconductor switches, one diode, and two electrolytic capacitors. Herein, series-parallel and conventional-series techniques are utilized effectively to balance the capacitor voltages. Further, cost and quantitative comparisons are carried among the state-of-art circuits to highlight the supremacy of proposed circuit. Subsequently, the performance of HNIT is verified experimentally with the fundamental switching PWM technique at different load conditions. © 2004-2012 IEEE.Item A novel nine-level boost inverter with a low component count for electric vehicle applications(John Wiley and Sons Ltd, 2021) Shiva Naik, B.S.; Yellasiri, Y.; Aditya, K.; Nageswar Rao, B.N.In electric vehicles (EVs), considerable battery cells are cascaded in series for motor driving to improve the output voltage. The series combination of battery cells causes challenges like isolation of faulty cells, voltage unbalance, and slow charge equalization. Therefore, state-of-charge (SOC) and voltage equalization circuits are often used in industries to protect the battery cells. A nine-level inverter circuit with a double voltage boost is proposed to reduce the above issues based on the switch-capacitor (SC) principle. Unique features like self-balancing, voltage boosting are attained, which cannot be achieved through traditional inverters. The proposed topology can operate at a wide range of modulation indices ((Formula presented.)) to produce different voltage levels. The absence of a back-end H-bridge in the proposed circuit offers low voltage stress across the semiconductors. The operating principle, capacitor sizing, and modulation approach are presented. Further, experimental tests are conducted at different loading conditions to verify the performance of the proposed circuit. © 2021 John Wiley & Sons Ltd.Item A novel single source multilevel inverter with hybrid switching technique(John Wiley and Sons Ltd, 2022) Nageswar Rao, B.; Yellasiri, Y.; Shiva Naik, B.; Venkataramanaiah, J.; Aditya, K.; Panda, A.A novel multilevel inverter (MLI) configuration with the hybrid switching technique is presented in this paper. The proposed MLI consists of the H-bridge combination with unidirectional switches, half-bridges, and transformers. The suggested MLI with the additional cascaded connection increases to higher voltage levels. The number of employed components in this topology is drastically minimized. Therefore, the complexity, cost, and volume of the proposed topology are also reduced. The operation of the suggested topology is tested through the improved novel switching technique. This modulation method reduces the total harmonic distortion (THD) and produces high root mean square (RMS) voltage. Further, a comprehensive comparison with the recent MLI topologies is performed to validate the merits of the suggested inverter. Simulation and experimental results verify the suggested topology performance using the new modulation technique at different loading conditions and modulation indices. © 2021 John Wiley & Sons, Ltd.Item A capacitor based single source MLI with natural balancing and less component for EV/HEV application(John Wiley and Sons Ltd, 2022) Aditya, K.; Yellasiri, Y.; Shiva Naik, B.; Nageswar Rao, B.; Panda, A.K.Due to their remarkable performance, capacitor-based inverters have recently gained attention. Hence, a new capacitor-based multilevel inverter is presented in this paper for electric and hybrid electric vehicle (EV and HEV) applications. EV systems are quite well for their use of two-level inverters; however, the generated load voltage comprises substantial undesirable harmonic content. It is regarded as one of the most efficient methods since replacing a two-level inverter with a multilevel inverter improves the power quality despite significantly reducing total harmonic distortion. Therefore, the recommended filter dimension will also be minimized. A flurry of reliability concerns has arisen due to the increased number of devices, circuit complexity, and stress on the circuit devices. A nine-level voltage waveform is created with only ten IGBTs, a DC-Source, and two capacitors. In the proposed nine-level inverter, the capacitor voltage is balanced utilizing a simple control approach to regulate the flying capacitor (FC) voltages actively. Here described a simple logic gate-based pulse-width modulation technique that ensures capacitor power balancing. The proposed inverter operation and capability are validated by experimental results derived from a laboratory prototype. Finally, by contrasting the new and standard inverter topologies, the virtues of the suggested architecture by the number of devices and price of the equipment are highlighted, and it is a simpler structure that requires less space and footprint area. © 2022 John Wiley & Sons Ltd.