A medium voltage AC drive with integrated isolation transformer and active front end

A current source inverter (CSI)-based medium voltage AC drive with PWM rectifier (active front end), sensorless vector control and symmetric gate commutated thyristors (SGCTs) is presented. A transformer is integrated to the drive system to provide isolation from the other loads. The design emphasizes ease of use and reliability by adopting a plug and play concept. The drive requires a total of six cable connections, three for the input and three for the output motor connections only. The use of the integral transformer further reduces the start up and installation cost and reduces the size of the overall system. The proposed system meets the harmonics requirements without the need for additional filters or complicated multiwinding transformers. Results for a 1000 hp 6600 V drive are included.