Application of Large Capacity Voltage Source Inverter to cylindrical rotor synchronous motor

The Large Capacity Voltage Source Inverter (LCVSI) application started early 90´s. The inverters are getting old and are beginning to be replaced with more recent drives. In March of 2010, a contract was awarded to replace the existing GTO (Gate Turn-Off thyristor) Inverter drives applied to cylindrical rotor synchronous motors on a two stand reversing cold rolling mill. New IEGT (Injection Enhanced Gate Transistor) drives were applied on the two rolling stands and both tension reels. Previous voltage source inverter was the GTO Inverter. Previous synchronous motor applications had been with salient pole type synchronous motor. The differences between GTO inverter and IEGT inverter are discussed. Cylindrical rotor and salient pole motor, design considerations for application of large scale voltage source inverters to cylindrical rotor motors, and results obtained during testing and commissioning are discussed.