High Temperature, High Frequency SiC Three Phase Inverter for Aircraft Applications 2010-01-1798

This paper presents the results of a silicon-carbide-based 300V 5 kW fully functional three-phase inverter module operating at high temperatures and device junctions up to 200°C. Each phase power module employs eight SemiSouth 100 mΩ/1200V SiC JFETs (SJEP120R100) in parallel per switch position. The paper will highlight both the electrical and the thermo-mechanical design. Experimental results validating the overall design will also be discussed.

The core of the electrical design was to take advantage of the low input capacitance, high switching frequency (50 kHz) and high temperature capability of the SiC JFET in order to obtain a high power density inverter. Since SemiSouth's SiC JFET is a relatively new device, computer models are not currently available from the manufacturer, which presents a hurdle during the design stage. In order to produce reliable performance predictions, the team has focused on developing a model for the SiC JFETs ultimately used. This paper will cover some of the strategies used to implement a first degree approximation model for the SiC devices. Since enhancement-mode SiC power JFETs (such as the ones used in the prototype) have a gate behavior different from that of traditional MOSFET-type devices, this paper will also present the gate driver strategy and ultimate gate driver hardware prototype developed to properly drive the enhancement mode SiC JFETs.

Packaging topics covered include material selection, high temperature processing issues, power substrate design, and system thermal analysis. Concluding the paper are the high temperature electrical test results of the prototype system.