High Performance Current Source Inverter Fed Induction Motor Drive with Minimal Harmonic Distortion

This paper discusses the minimization of the line- and motor-side harmonics in a high power current source drive system. The proposed control achieves speed regulation over the entire speed range with enhanced transient performance and minimal harmonic distortion of the line and motor currents while limiting the switching frequency of current source converters to a maximum of 540 Hz. To minimize the motor current harmonic distortion, space vector modulation (SVM) and selective harmonic elimination (SHE) schemes are optimally implemented according to different drive operating conditions. In order to suppress line- side resonant harmonics, an active damping method using a combination of a virtual harmonic resistor and a three-step modulation signal regulator is employed. The performance of the proposed current source drive is verified by simulation for a 1 MVA system and experiments on a 10 kVA gate-commutated thyristor (GCT) based laboratory drive system.