000			02849nam a22001937a 4500
082			_a621.3 _bK114M
100			_aKachhwaha, Mohit _926060
245			_aModelling of Z and Quasi Z- Source DC-DC Converters for Variable Frequency Operation _cby Mohit Kachhwaha
260			_aIIT Jodhpur _bDepartment of Electrical Engineering _c2017
300			_axi,38p. _bHB
520			_a"The impedance source network, proposed in the year 2002, nsists of a unique combination of two inductors and two capacitors. This network has proven its expediency over the conventional voltage source and current source networks as an efficient mean of power conversion in a wide spectrum of electric power applications. These converters, conventionally, are operated at an optimized fixed frequency. However, an optimized switching frequency may achieve its maximum efficiency only under the given set of operating conditions whilst under different operating conditions there is actually a degradation of conversion efficiency. Therefore, in an attempt to cater to energy conformity demands, to maintain constant efficiency over the entire load range, an alteration is required in the switching frequency based on the current status of the system. In this thesis, the domain of these impedance source networks is explored for variable frequency operations. The work deals with two topologies of impedance source networks, viz., traditional Z source network and quasi Z source network. Complete circuit analysis is carried out for both topologies and system models are obtained for the different modes of operation. Instead of commonly used approach of state-space averaging, an enhanced model of the converters is presented for variable frequency operation. These proposed models are achieved by considering the on-time and the off-time of the switching period as separate control variables for state-space averaging. The obtained ac small signal models are then subjected to simulation and experimentation to clearly demonstrate and confirm the accuracy of the proposal. This enhanced model, for the widely acclaimed impedance source networks, captures the dynamics of the power conversion system under variable frequency operation. The adopted averaging method is a flexible approach, wherein, responses to a constant on-time, constant off-time as well as a varying on-time and off-time can be studied. These accurate models would help to fully exploit the switching period modulation in terms of transient performance and to ensure stability in all operating conditions. i"
650			_aQuasi Z- Source _926061
650			_aDC-DC Converters _926062
650			_aVariable Frequency Operation _926063
650			_aMTech Theses _926064
650			_aDepartment of Electrical Engineering _926065
700			_aFulwani, Deepak _926066
942			_cTH
999			_c14681 _d14681