PERFORMANCE ANALYSIS OF MULTICARRIER SPWM STRATEGIES FOR THREE PHASE Z - SOURCE SEVEN LEVEL CASCADE INVERTER

Multilevel inverter is one of the attractive topology for DC to ac conversion. Multilevel inverter synthesizes desired voltage wave shape from several levels of DC voltages. But main drawback of MLI is its output voltage amplitude is limited to the DC sources voltage summation. To overcome this limitation a five level Z source cascaded H bridg e multilevel inverter has been proposed here. In the proposed topology output voltage amplitude is boosted with the Z network shoot through state control. It employs the Z network between DC source and inverter circuitry to achieve the boost operation. Out put voltage of proposed inverter is controlled using modulation index and shoots through state. The Performance parameters of Z Source Multilevel inverter is analyzed for unipolar modulation and space vector modulation. In this thesis multilevel inverter based Z source is proposed which can solve above mentioned problems. The Z source inverter utilizes Z impedance network between the DC source and the inverter circuit to achieve buck boost operation. It utilizes shoot through state control to boost the inp ut dc voltage of inverter switches when both switches in the same phase leg are on. The Z Source inverters have advantages such as lower costs reliable lower complexity and higher efficiency. Simulation model of Z source cascaded multilevel inverter with u nipolar ISCPWM unipolar CDPWM and SVM Modulation technique has been built in MATLAB/SIMULINK and its performance has been analyzed