R DS(on) vs. inductance: comparison of SiC MOSFETs in 7pin D2Pak and 4pin TO‐247 and their benefits for high‐power MHz inverters

Abstract

In this work, the authors present their investigations of the benefits of combining the latest silicon carbide MOSFETs with novel packages for electronic ballasts of inductively coupled plasmas. Such plasmas require MHz inverters with output powers above 2 kW. Additionally, for a breakthrough of the technology efficiencies >90% have to be realised. It has been shown that a combination is achievable with SiC FETs. Nevertheless, even though the transistors have undergone significant development in recent years, one limiting factor has mostly remained untouched. The common TO-247 package does not fit to the requirements of a fast switching application. Within the latest launch of the new generations of SiC MOSFETs, some are available in novel packages with kelvin source connection, like 4pin TO-247 and 7pin D2Pak. The authors compare three versions of the latest generation in a resonant full-bridge inverter and in application-oriented test. Thereby, the 7pin D2Pak and one of the 4pin TO-247 transistors were 65 mΩ devices and the second 4pin TO-247 FET was a 45 mΩ device. For the investigations, the authors made simulations, built three MHz inverters, and conducted measurements. Consequently, efficiencies of 93.9% could be achieved at a switching frequency of 2.5 MHz and an output power of P out =2.6 kW.