Medium voltage drive converter for industrial applications in the power range from 0.5 MW to 5 MW based on a three-level converter equipped with IGCTs

A power converter is described that is intended to open the market for a broader number of applications for electrical variable speed drives. The idea was to develop a converter that could be easily applied to any kind of new or existing medium voltage industrial drive. This included the goal to get a very compact converter, to be flexible concerning the placement of the transformer and to design this converter for a high reliability. An in-depth study of all kinds of concepts resulted in the chosen one, which is a neutral-point clamped inverter with a 12 pulse diode bridge at the grid side. The output is connected to the motor via a LC output filter that is designed to achieve a sinusoidal output voltage. The control concept chosen is direct torque control (DTC), which has proven its outstanding performance in more than 150 000 existing low-voltage drives converters.