On the use of front-end cascode rectifiers based on normally-on SiC JFET and Si MOSFET

Abstract

The new wide band-gap semiconductor devices provide new properties to be explored. Normally-on Silicon Carbide (SiC) JFET power devices have several advantages, in particular low switching losses, high temperature operation and high reverse voltage capability. Looking for improve the overall efficiency in power converters, new structures based on these power devices might be studied. In this paper, a cascode rectifier based on normally-on SiC JFET is presented and analyzed. This new rectification structure can be applied as front-end rectifier stage for AC-DC power converters, increasing the overall efficiency of these topologies. A second cascode rectifier based on Silicon (Si) MOSFET is also studied, as a low cost alternative. Both cascode structures are compared with traditional Si rectifier diodes and front-end rectifiers, using three different test circuits: a full bridge rectifier, a passive Power Factor Corrector (PFC) voltage doubler and an active PFC interleaved boost converter. As a result of this comparison, an efficiency improvement as high as two points is obtained on each tested circuit.