Comparison of large power variable speed drive concepts

Today, practically all smaller power converters are voltage source converters using IGBT (insulated gate bipolar transistor) technology. These voltage source converters are on a course of development with ever expanding voltage and power capability. The powerful and fast IGBT however creates problems in respect to voltage stress, EMI (electromagnetic interference) and reliability. In the higher power range, voltage and current source power converter concepts are still competing. Current source converters were formerly attractive due to tight control of the converter current. Their drawback is their limited performance, especially in terms of dynamics. Careful consideration of line harmonics effects, filtering, EMI and the voltage stress on motor windings allows to edge out advantages for the older current source concepts.