Multi-megawatt drive with intercell transformers

In order to provide excellent harmonic power quality equivalent to that of a synchronous generator, interleaved carriers and intercell transformers (ICTs) were included as part of an active-front end in a two-level, four-thread three-phase PWM drive to try to achieve 1% Total Harmonic Distortion (THD) and 0.3% Single Harmonic Distortion (SHD) for voltage up to 20 kHz on a high impedance grid. This highly compact drive rated up to 4 MW at 690 V with 2.5 kHz switching frequency is currently undergoing testing on a 480 V grid. The results of harmonic testing to date as well as a discussion of the role of the various inductance values associated with the design are included.