A new 7.2kV medium voltage 3-Level-NPC inverter using 6.5kV-IGBTs

The SINAMICS GM150 IGBT, a new 3-level-neutral-point-clamped (3L-NPC) Voltage-Source- Converter (VSC) with series-connected 6.5 kV-IGBTs for industrial Medium Voltage Drives is presented. It covers the output voltage range from 6 kV up to 7.2 kV without the need for a step-up output transformer. The SINAMICS GM150 IGBT is based on the proven basic design of its predecessor SIMOVERT MV while the output voltage and current ratings have been extended. The maximum available output power of the water cooled version with a parallel connection of two inverters is 8.7 MVA at an output voltage of 7.2 kV. For the power section state of the art IGBT modules with AlSiC base plates are used. The dynamic voltage sharing for the IGBTs is done by the gate drive units without any additional passive snubber circuits. For the NPC-diodes small passive snubber circuits are used to ensure the dynamic voltage balancing. The mechanical design, the semiconductor ratings and the available converter performance of the SINAMICS GM150 (IGBT) is described. An additional focus is put on the semiconductor switching characteristics in series-connection as well as on the design and the performance of the sinusoidal output filter which is required in retrofit applications with conventional line motors.