Novel Control Algorithm for V/f Control of PWAM Based Induction Motor Drive

In this paper, three-phase induction motor supplied by multilevel quasi impedance source inverter (qZSI) is controlled with V/f technique. Application of pulse width amplitude modulation (PWAM) technique for controlling the multilevel qZSI is implemented. In PWAM, modulation index which is defined as the ratio of peak of modulating signal to the peak of carrier signal always remains unity. Due to this, the voltage available at the output of the inverter is not controlled in correspondence to V/f control during starting of induction motor. In this paper, a novel control algorithm is proposed which helps in achieving starting of induction motor without starting current transients. Performance of Vlf-controlled induction motor drive obtained with different modulation techniques are compared by simulating the three - phase induction motor drive using Simulink. Comparison of switching losses with these methods is also presented. Experimental prototype of closed loop controlled three - phase seven - level qZSI is developed and tested with RL load.