Design and Performance Evaluation of a 200 °C Interleaved Boost Converter

Recent advances in silicon carbide (SiC) power semiconductor technology and resulting availability of SiC Schottky rectifiers and controlled devices (bipolar junction transistors, JFETs, and MOSFETs) make it possible to design and implement power converters capable of operating at 200 °C. The design, prototype development, operation, and testing of a 74 kHz, 2 kW, 100 V/270 V inversely coupled, interleaved, dc-dc boost converter over the 20-200 °C temperature range is presented in this paper. The advantages of coupled-inductor interleaved boost converters include increased efficiency, reduced size, reduced electromagnetic emission, faster transient response, and improved reliability. Optimization of a high temperature X-perm core-based coupled inductor architecture, in terms of ac flux balancing and dc flux cancellation is discussed. DC characterization of SiC power devices used in the design (Schottky rectifier and JFET) over the 20-200 °C temperature range is presented as well. The power stage of the converter, including the power semiconductor devices, coupled inductor, and X7R ceramic input and output filter capacitors, was placed inside a temperature controlled chamber for testing. JFET gate drive circuit, input power source, and output load were external to the environmental chamber. Converter testing and performance evaluation was accomplished over a 20-200 °C ambient temperature range. As expected, JFET conduction loss increased and converter efficiency decreased with increasing temperatures. The drop in converter efficiency was in the range of 2%-4% over the entire load (200 W to 2 kW) and temperature (20-200 °C) ranges evaluated. At 200 °C, output voltage ripple increased by ∼60% due to the rapid decline in X7R capacitance at the high-temperature extreme. The results obtained during this study suggest that the realization of 200 °C power converters is feasible through a judicious selection of power semiconductor devices, magnetic core materials, and capacitor dielectrics. As a result, high temperature, frequency, and power density converters are expected to be a reality in the near future.