Power Flow Control in Induction Motor by using a Symmetrical Multilevel Inverter

Abstract

The Assymetrical multilevel inverter topology is used for the optimization of levels with a mimimum no. of voltage sources. It is used where medium voltage and higher power is required. There are three or four H-bridge of single phase inverter (consist of MOSFET or Optocoupler) connected to Induction motor. All H-Bridges are working with different votage sources bases on the G.P ratio (2or3). A multilevel inverter is more advantageous in comparison with a conventional two-level converter that uses high switching frequency pulse width modulation (PWM). The increase in the number of level in multilevel inverter reduces the total harmonic distortion (THD), common mode voltages, the output filters and the switching losses and hence power flow can be controlled by providing smooth A.C sine wave to the induction motor to mainly prevent the reduction of the efficiency of the motor due to harmonics which are present in normal power supply. But in multilevel there are also some limitations if we will go for higher levels i.e. beyond 27 level that we will also see here in detail description by the results of simulation done on MATLAB7.10.