Research into new diode material for frequency inverters

A new material is set 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. Such an approach will reduce inverter energy losses by as much as 15%. The recently launched research project is receiving approximately €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 that are operated at variable speeds. These motors require frequency inverters that convert the normal power line frequency of 50 Hz into a variable frequency that ranges from zero to approximately 200 Hz. The inverters function much like a dimmer for controlling the brightness of a light source.

The MV-SiC research project seeks to substantially increase the efficiency of these inverters. This is to be accomplished by new types of diode modules based on the semiconducting material silicon carbide (SiC). Along with improved efficiency, the researchers also believe that use of the SiC 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 to date.

The MV-SiC project was launched in June 2010 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.