Design-in for SiC: HV pulse generators use silicon carbide MOSFETs

March 04, 2015 // By Graham Prophet
Rohm Semiconductor’s SCT2080KE SiC MOSFET are providing key functions in ultra-high voltage pulse generators (SiC-Pulser Series) launched by Fukushima SiC Applied Engineering Inc. in November, 2014.

This class of pulse generators is used in a variety of applications, including high voltage accelerators, plasma generators, and laser processing machines. Conventional systems use silicon devices or vacuum tubes as switching elements. However this often entails a large number of system components which often results in very high construction and installation costs.

By making use of the silicon carbide transistors’ combination of high breakdown voltage with low on-resistance and high-speed switching performance, the designers in this instance were able to build pulse generators that are considerably smaller and provide a level of performance that cannot be achieved with conventional systems.

According to Fukushima SiC Applied Engineering Inc. President Kokubo, “In developing a revolutionary breakthrough pulse generator we evaluated a number of different switching elements. As a result, we determined that Rohm’s SiC MOSFET was able to meet our criteria for reliability and performance. This marks the world’s first practical application of SiC in a pulse generator.” He also explained how different this system was from conventional ones. “For example, when trying to achieve a normal conducting linac (linear accelerator) with a beam output on the order of tens of kW, conventional vacuum tube acceleration technology will result in a linac that is 1600m long. However by adopting SiC-based acceleration technology we can reduce the length of the linac to less than 6m, thereby decreasing construction and installation costs significantly.”

Rohm is ramping up production of SiC products specifically for the power sector. The SCT2080KE SiC MOSFET reduces switching losses by more than 70% when compared to Si IGBTs used in general inverters. Support for higher switching frequencies allows the use of smaller peripheral components, contributing to end-product miniaturisation. SiC devices are already employed in converters and inverters in industrial equipment and power conditioners in solar power systems, and Rohm is exploring new markets for SiC devices.

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