Analysis and performance evaluation of Z Source multilevel inverter for induction motor drives

Abstract

Multilevel inverters play important role in electrical power conversion process An inverter converts power from the DC to AC form Conversion from DC to AC is much demanding since some of the renewable energy sources like solar photo voltaic panels fuel cell and battery are capable of delivering DC power supply only Converting DC into AC is a process carried out by inverters and the inversion process needs certain important metrics to be maintained The achievement of required AC voltage or current output number of phases frequency phase and its quality with respect to pure sinusoidal waveform are important considerations. A large number of distributed DC sources of low voltage levels are integrated in a common inverter to built multilevel inverters Besides there are some important advantages of the multilevel inverters The multilevel inverter has been built to produce higher voltage levels with power electronic components of lower rating This is possible by cascading the power electronic switches or inverter modules of lower voltage rating than the rated output voltage of a multilevel inverter In a conventional three level inverter of the full bridge configuration with four switches the output voltage is limited to the source DC voltage and its THD is high If a number of such bridges are cascaded to get a higher AC output voltage output The wave form of AC voltage obtained can be shaped to be close to a sine wave with reduced THD Inverters are built either as a voltage or current source inverters The voltage source inverter produces an output voltage that is independent of the load impedance a current source inverter can deliver output currents independent of load impedance newline