Dodecagonal Space Vector PWM for Two Level Inverter Fed Open End Winding Induction Motor Drive

Abstract: A dodecagonal space vector pulse width modulation method for a two level inverter fed open end winding induction motor is discussed. Space vector PWM (SVPWM) method is one of the best suited controlling techniques as it reveals better utilisation of dc link voltage, high modulation index and posses only less harmonics compared to other methods. For conventional hexagonal SVPWM, output voltage is not purely sinusoidal which results in more harmonic contents. So to overcome this problem, 12 sided SVPWM is used. Since the 12 sided polygonal structure is near to a circular shape, the output so obtained will be near to sinusoidal. This will reduce the harmonics and a better input is given to the induction motor. It can be seen that fifth and seventh order harmonics is completely eliminated from the output voltage. Dodecagonal SVPWM is achieved by connecting two 2 level inverters on both sides of an open end winding induction motor. Here equal power is fed from both ends of the induction motor and the inverters which are of half the rated machine can be used. Thus the cost regarding the inverters can be reduced. Here, dodecagonal space vector PWM for two level inverter fed open end winding induction motor is simulated in MATLAB and the simulation results obtained shows that the Total Harmonic Distortion (THD) is only 4.34% for an output phase voltage of 415 V with a speed of 1425 rpm. Keywords: Space Vector Pulse Width Modulation (SVPWM), Dodecagonal SVPWM, Total Harmonic Distortion (THD), Open End Winding Induction Motor, Sinusoidal Pulse Width Modulation (SPWM).