Faculty Publications
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Item Modified Hysteresis Current Control for Single Phase Solar Grid-tie Z-Source Inverter(Institute of Electrical and Electronics Engineers Inc., 2018) Damodaran, R.; Balasubramanian, B.; Mudlapur, A.; Ramana, V.V.; Mishra, S.This paper proposes a simple novel technique to determine the shoot-through states in a hysteresis controlled solar grid connected single phase Z-source inverter (ZSI). The ZSI along with the proposed controller exhibits high efficiency due to the single stage conversion. Fast and robust dynamic response can be obtained by using hysteresis control. Hence the proposed control for ZSI is ideal for grid integration of photovoltaic sources. The error current is used to determine shoot-through states based on calculation of current limits as a function of the boost ratio and modulation index. The maximum boost ratio, that can be obtained by the proposed control without causing low frequency ripples in Z-source network, is expressed as a function of modulation index. To verify the analysis, simulations are performed for input and grid voltage variations using MATLAB-Simulink platform. © 2018 IEEE.Item Global Peak Tracking of Photovoltaic Array under Mismatching Conditions Using Current Control(Institute of Electrical and Electronics Engineers Inc., 2019) Ramana, V.V.; Mudlapur, M.; Damodaran, R.; Balasubramanian, B.; Mishra, S.Characteristics of photovoltaic arrays exhibit multiple peaks under mismatching conditions. In order to harness maximum energy, it is imperative to track the global maximum power point. A novel global peak tracking algorithm is proposed using current control in this paper. The proposed method operates in the backward phase and forward phase to track the global peak. The objective of the proposed algorithm is to track the global maximum accurately with minimum tracking time. The enhanced performance of the proposed algorithm is verified using simulations by comparing it with an existing method. Experimental validation is done using a solar array simulator, boost converter, resistive load, and dSPACE controller. Experimental results are in close agreement with simulation. The proposed algorithm is intended to track the global peak of a PV string that contains a group of modules. © 1986-2012 IEEE.Item An Iterative Analytical Solution for Calculating Maximum Power Point in Photovoltaic Systems under Partial Shading Conditions(Institute of Electrical and Electronics Engineers Inc., 2019) Mudlapur, M.; Ramana, V.V.; Damodaran, R.; Balasubramanian, B.Detection of maximum power point (MPP) is one of the most sought-after topics in the field of photovoltaic systems. There are many approaches to detecting MPP, amongst these are analytical methods. Analytical methods use mathematical functions to solve the given problem and therefore are one of the dominant strategies. However, their applications to detect MPP have been limited to study only uniform shading conditions. The use of analytical methods to detect MPP for more challenging cases like partial shading conditions is yet to be investigated. In this brief, an analytical solution to identify MPP under partial shading conditions is proposed. Equations describing photovoltaic panels and MPP conditions are derived by applying fundamental circuit laws. The derived equations are non-linear and can be solved using numerical techniques available in most of the simulation packages. The proposed model can theoretically detect the MPP amongst 'N' peaks. The results from the simulation are verified by conducting experimentation with standard algorithms available in the literature. The results from simulation and experimentation are found to agree with each other. © 2004-2012 IEEE.Item Small Signal Model for PV Fed Boost Converter in Continuous and Discontinuous Conduction Modes(Institute of Electrical and Electronics Engineers Inc., 2019) Mudlapur, M.; Ramana, V.V.; Damodaran, R.; Balasubramanian, B.Small signal models are of high importance in power electronic systems which exhibit highly non-linear properties. They provide access to stability and help in tuning controllers. Small signal models for many power electronic converters are seen in the literature. However, specific applications like photovoltaic systems demand the addition of a capacitor at the terminals of photovoltaic (PV) panel. Since this capacitor is connected between the PV panel terminals and the input of power converter, it is termed as input capacitor. The effect of the addition of input capacitor on system stability has not been addressed yet. In this brief, we derive the small signal models for PV fed boost converter operating in both continuous conduction mode (CCM) and discontinuous conduction modes (DCM) of operation. The load is assumed as purely resistive; however, the analysis holds good for any practical loads. It is observed that in both CCM and DCM the stability of the maximum power point tracking (MPPT) system is independent of the input capacitance. It is also shown that the MPPT system is open loop stable for all operating conditions. The studied models are further validated with the experimental setup. © 2004-2012 IEEE.