Medium voltage drive system with NPC three-level inverter using IGBTs

This paper presents a medium voltage motor drive consisting of a twelve-pulse diode rectifier and a three-level neutral point clamped inverter using high-voltage IGBTs. Innovative features of the drive include series-connection of high-voltage. The motor control is based on field-oriented vector control and an optimised PWM modulator, so that switching losses and current harmonics are minimised, resulting in no motor derating. Together with modern SIEMENS medium voltage motors the inverter can be operated directly without any additional filter. In the case of old motors or third party motors a sinusoidal output filter is available