Conference Papers

Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/28506

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Author: search.filters.author.Yaragatti, R.Y.Subject: search.filters.subject.multilevel inverter

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    A comparison of seven-level inverter topologies for multilevel DC-AC power conversion
    (Institute of Electrical and Electronics Engineers Inc., 2014) Salodkar, P.; Sandeep, N.; Kulkarni, P.S.; Yaragatti, R.Y.
    Multilevel inverter (MLI) performance is high compared to the conventional two level inverters since they offer high power capability, associated with lower output harmonics and lower commutation losses. However the main drawback of MLI is their increased number of power devices, passive components, complex pulse width modulation control and balancing of capacitor voltages. In this paper the most popular topologies like diode-clamped inverter (neutral-point clamped), cascaded multicell with separate dc sources, and transistor clamped H-Bridge inverter are discussed. A simplified multilevel inverter (Switched Transistor MLI) is proposed and its performance is compared with the above said topologies. Component count and the % total harmonic distortion (THD) of the output voltage are considered as the indexes of the comparative performance. The operating principle of each topology, the most relevant modulation method of all the topologies and the detailed analysis of the proposed Switched Transistor MLI is included. The selection of topology and control techniques depends and varies according to power demands of inverter. Simulation study of all the topologies considered is carried out on MATLAB/SIMULINK platform and the performance of the proposed topology is verified experimentally by the tests performed on a scaled laboratory prototype. © 2014 IEEE.
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    Single-phase modular multilevel inverter based grid-connected photovoltaic system
    (Institute of Electrical and Electronics Engineers Inc., 2016) Sandeep, N.; Yaragatti, R.Y.
    This paper presents a control scheme for single-phase grid-connected modular five-level inverter applied to photovoltaic (PV) system. The five-level topology considered consists of two series connected H-bridge cells popularly known as cascaded H-bridge inverter. The reason that it requires an isolated dc sources makes it very attractive and its inherent modularity, easy scalability makes the system more reliable. One of the main challenges associated with multilevel converter is to control the drift in dc-link voltage caused by the power imbalance of the cells. A two loop control scheme is proposed to combat this issue; it consists of an asynchronous frame or proportional resonant (PR) for regulating the grid current and a proportional integral (PI) controller for regulating dc-link voltage. The proposed scheme regulates the dc-link voltage independently, in accordance with the reference value generated by the maximum power point tracking (MPPT) algorithm enabling the extraction of maximum power from each module. The inverter injects current which is in phase with the grid voltage ensures the unitary power factor operation with zero reactive power and less total harmonic distortion. The proposed control scheme can be extended to any number of cells connected in series for increasing the number of level in output voltage. Simulation results are presented to validate the analytical expectations and the control scheme developed. © 2015 IEEE.