Topology and Control Method Development for Impedance Source Converter

Abstract

The improved characteristics of impedance source converters presented in recent literatures such as efficient power conversion, single stage buck-boost capability and reliability compared to voltage/current source inverters have made it a suitable candidate for a variety of distributed generation power applications. The limitations of VSI (voltage source inverter) and CSI (current source inverter) are removed by impedance source inverter (ZSI). It is well established that the null state included in the pulse width modulation scheme of a voltage source inverter is foundation for Z-Source inverter. There are mainly two states in the case of impedance source inverter, shoot-through and non-shoot-through states. In ST (shoot-through) the inductor charges and at NST (non-shoot-through) it discharges. In NST state, the inductor voltage adds up with the source voltage and a boosted output voltage is achieved. In this thesis, analysis of different control techniques, SBC (simple boost control), MBC (maximum boost control), and MCBC (maximum constant boost control) in terms of output voltages, total harmonic distortion, voltage stress, boost factor, and gain is discussed in detail. The core work of this thesis is the generation of ST pulses with three different control methods and their comparison, so that suitable control method can be selected for different applications. Simulation is carried out in MATLAB Simulink and results are presented to verify the mathematical findings. Different graphs have been plotted to highlight the merits/demerits of the proposed control techniques. Experimental results are presented to justify the theoretical and simulation results.