Silicon carbide research may give better inverters

A new material is poised to make the frequency inverters used with large electric motors more efficient and powerful. Together with several partners, researchers from Siemens Corporate Technology and experts for large electrical drives at Siemens Industry Drive Technologies are studying how the semiconductor silicon carbide can be used as a diode material in place of pure silicon.

This would reduce inverter energy losses by up to 15%. The recently launched research project is receiving about €1.7 million in funding from the German Ministry of Education and Research.

Large machines such as pipeline pumps and compressors for natural gas liquefaction systems and ship propulsion systems are currently powered almost exclusively by electric motors operated at variable speeds.

The motors require frequency inverters that convert the normal European power line frequency of 50 Hz into a variable frequency that ranges from zero to about 200 Hz. The inverters function much like a dimmer for controlling the brightness of a light source.

The MV-SiC research project hopes to substantially increase the efficiency of these inverters by new types of diode modules based on the semiconducting material silicon carbide (SiC). Along with improved efficiency, the researchers also believe that these diodes will enhance the reliability and safety of the inverters.

Siemens is carrying out pioneering work in the project, as comparable SiC high-voltage diodes operating in the medium-voltage range have not been used anywhere in the world.

The project was launched in June and will run until April 2013. It is part of the 'Power Electronics for Improved Energy Efficiency' initiative, which in turn is a component of the German government’s High-Tech Strategy and the 'Information and Communication Technology 2020' (ICT 2020) program.

One of the goals of the latter is to achieve greater energy efficiency and reduce pollutant emissions through the application of new developments in power electronics systems.

Along with Siemens, ICT participants include the Technical University of Dresden, Infineon, Curamik Electronics, and SiCED Electronics Development.