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Subject: search.filters.subject.Cascaded H-bridge

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    A novel technique for control of Cascaded multilevel inverter for photovoltaic power supplies
    (IEEE Computer Society, 2005) Naik, R.L.; Udaya Kumar, R.Y.
    Multilevel voltage source inverters offer several advantages compared to their conventional counterparts. By synthesizing the AC output terminal voltage from several levels of voltages, staircase wave forms can produced, which approach the sinusoidal wave form with low harmonic distortion, thus reducing filter requirements. The need of several sources on the DC side of the converter makes multilevel technology attractive for photovoltaic applications. The basic modulation techniques enable harmonic elimination by predetermination of the switching angles. This is determined according to a previously calculated and stored pulse width modulated waveform. It has the advantage of operating at fundamental frequency switching. However, this technique is seriously limited as the number of levels increases because of the increased complexity and the reduced accuracy of the non-linear solutions. This paper proposes a novel Multilevel PWM technique (phase-shifted sinusoidal PWM) to over come all these limitations while maintaining switching at fundamental frequency, found better THD. Simulation results are presented in the paper.
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    A new method for selecting optimum levels in asymmetric Cascaded H-Bridge-Multilevel Inveter with variable DC sources
    (John Wiley and Sons Ltd, 2025) Venkataramanaiah, J.; Yadav, G.; Balaji, J.; Yellasiri, Y.
    In general, cascaded H-bridge multilevel inverters (CHB-MLI) are typically operated with either symmetrical or asymmetrical input DC sources, set at predefined specific ratios such as binary (1:2) or trinary (1:3) in the case of asymmetry, to achieve the desired output voltage waveform. However, if any DC source fails to provide the predefined voltage magnitude, or CHB-MLIs with unspecified DC source ratios are utilized, the output voltage waveform may exhibit unequal magnitudes between consecutive levels, thereby causing a significant increase in total harmonic distortion (THD). Conventionally, to mitigate this effect, the corresponding H-bridge is bypassed through zero voltage switching, which leads to an additional burden on the remaining H-bridges to serve the same load. To reduce the burden on the remaining cells and improve the THD profile of the inverter, this article proposes a novel method for CHB-MLI with varying DC magnitudes. It aims to enhance the quality of the output voltage waveform by strategically selecting optimum voltage levels rather than utilizing all available levels when CHB-MLI has unspecified or variable DC sources. This approach can achieve a more balanced distribution of voltage magnitudes across successive levels by eliminating redundant states. Moreover, the proposed technique can reduce switch losses and enhance the converter's efficiency. The proposed method is validated through MATLAB/Simulink software simulations, followed by experimental verification. © 2024 John Wiley & Sons Ltd.