Reaping the benefits from innovative modular-multilevel-converter technology for medium voltage drives

Cell-based, multilevel converters provide an attractive solution in the design and application of medium voltage drives. A medium voltage drive using Modular Multilevel Converter (M2C) technology offers the same superior performance as cell-based, multilevel converters while adding the flexibility and configurability of a drive with a common DC link.

The SINAMICS PERFECT HARMONY GH150 utilizes M2C technology for applications in the medium-voltage range of 4-13.8 kV providing flexibility and reliability. The M2C topology connects low voltage power cells in series to produce a medium voltage output. Each phase consists of two arms and their associated arm inductors. The power cell consists of two IGBTs and one capacitor bank in the simplest case.

For medium voltage drives, each power cell has two terminals and is equipped with low voltage (LV) IGBTs and self-healing film capacitors. This topology is flexible as it offers the possibility to select the number of line-side pulses since it is not dependent on the number of cells available in the motor-side inverter. This also allows for the use of a separate standard converter transformer.

Equally crucial for operators is reliability, and as with all mechanical systems, random failures of individual components—even with the most meticulous engineering and 100% testing—are unavoidable. The M2C technology can integrate redundant power cells into the drive, unlike other topologies. This allows drives to be designed so that, upon failure of a power cell in one arm, the remaining power cells are not subjected to higher voltage stress.

To learn more about how the flexibility and reliability of GH150 medium voltage drive can enhance operations, register for our webinar “A New Approach to Large Medium Voltage Drives.”