Over 99.7% Efficiency at 100kW DC-DC Power Conversion using a 3.3kV SiC Device and Discussion on Device dv/dt Estimation

Abstract

This paper is a re-evaluation of a completed project (High Efficiency Demonstration Grant Using High Voltage SiC Device) from the perspective of accurate efficiency measurement; additionally, this paper discusses on device dv/dt estimation. A topology called the high-efficiency energy conversion system (HEECS), which is one variety of partial boost circuit topologies, is introduced to achieve efficiency over 99.5%. The topology exhibits a very high efficiency for applications in which the output voltage variation is within a certain ratio of the rated output voltage. This paper summarizes the basic features of the topology and theoretically derives the principle of high-efficiency realization. The high efficiency is measured by the back-to-back (BTB) connection of two converters, and the efficiency and accuracy on this method are theoretically derived and confirmed using the measured data of 3.3kV output voltage at 100kW output. The theoretical estimation of dv/dt for a 3.3kV SiC device to reduce dual-active-bridge (DAB) soft-switching loss is discussed. Furthermore, a trend of DC-DC conversion efficiency is shown, and we show that the partial boost topology is a promising approach for achieving high efficiency dc-dc conversion.