Performance Analysis of Three Phase Cascaded Multilevel Inverter (CMLI) for Induction Motor Drives


Traditional high-frequency pulse width modulation (PWM) inverters for motor driveshave several problems associated with their high switching frequency which produceshigh voltage change (dv/dt) rates. Multilevel inverters solve these problems because theirdevices switch at the fundamental frequency. The concept of multilevel voltage sourceinverter is explained. In this paper the cascade inverter is a natural fit for induction motordrives because of the high VA ratings possible and it uses several levels of separate equaldc voltage sources which would be available from batteries or fuel cells. The switchingangles of switch devices are determined by optimized harmonic stepped waveform(OHSW) technique to reduce the output harmonics of cascade multilevel inverter (CMLI)for induction motor is proposed, as a result the efficiency of system has improved.Simulation results show the superiority of this inverter over 2-level inverter and werecarried out using ORCAD package.


Three phase CMLI, OHSW, HF, HLF, DF, THD