Constant v/f medium voltage high-power induction motor drive with synchronized SVPW

Space vector pulse width modulation is the most preferred for three phase voltage source inverter. It has better total harmonic distortion and higher DC bus utilization compared to other pulse-width modulation techniques. The three-level voltage source inverter is preferred over the two-level inverter for high-power drives. In high power drives the switching frequency of the inverter is normally low which causes the output voltage and current of the inverter to be rich in harmonics. In such condition, synchronized space vector pulse width modulation with symmetrical output voltages is employed. Constant v/f induction motor are widely used in medium voltage high-power applications such as pumps, fan drives, compressor drives etc. This thesis presents a closed loop control of constant v/f medium voltage high-power induction motor with synchronized space vector pulse width modulation technique that is capable of achieving synchronization, half wave symmetry, quarter wave symmetry and three phase symmetry. The synchronized space vector pulse width modulation guarantees the elimination of sub-harmonic, even harmonics and triplen harmonics in the output voltage. Hence the proposed drive will ensure improved total harmonic distortion at low switching frequency. The proposed technique is verified through simulation and experiment. The results show suppression of even harmonics, triplen harmonics and subharmonics from the output voltage. Stator resistance voltage drop compensation is used to overcome the problem of oscillation in low speed operation.