Switching Performance Comparison of the SiC JFET and SiC JFET/Si MOSFET Cascode Configuration

Abstract

Silicon Carbide (SiC) devices are becoming increasingly available on the market due to the mature stage of development fact of their manufacturing process. Their numerous advantages compared to silicon (Si) devices, such as, for example, higher blocking capability, lower conduction voltage drop and faster transitions make them more suitable for high-power and high-frequency converters. The aim of this paper is to study the switching behavior of the two most-widely studied configurations of SiC devices in the literature: the normally-on SiC JFET and the cascode using a normally-on SiC JFET and a low-voltage Si MOSFET. A detailed comparison of the turn-on and turn-off losses of both configurations is provided and the results are verified against experimental efficiency results obtained in a boost converter operating in both Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). Furthermore, special attention will be paid to the switching behavior of the cascode configuration, analyzing the effect of its low-voltage Si MOSFET and comparing different devices. The study carried out will confirm that the overall switching losses of the JFET are lower, making it more suitable for operating in CCM in terms of the overall converter efficiency. However, the lower turn-off losses of the cascode show this device to be more suitable for DCM when ZVS is achieved at the turn-on of the main switch. Finally, all the theoretical results have been verified in an experimental 600W boost converter.

Static and switching characteristics of 3.3 kV double channel-doped SiC vertical junction field effect transistor in cascode configuration

“…There have been several reports on high-voltage normally-off or normally-on JFETs. [23][24][25][26][27][28] The on-resistance in these reports could not be sufficiently reduced, while a high blocking voltage was achieved.…”

Modelling of Dynamic Properties of Silicon Carbide Junction Field-Effect Transistors (JFETs)

“…On the other hand, the structure of a real JFET contains p-n junctions of different electrical properties [21], so a separate set of M, PB and FC parameters has to be used. In the proposed model, independent descriptions of each junction were introduced to increase the modelling accuracy, according to equations:…”

“…Recently, a successful attempt at modeling the static characteristics and parameters of SiC-JFETs using the S-H model have been reported [19,20]. On the other hand, selected aspects of modelling dynamic characteristics of JFETs were presented in [8][9][10][21][22][23][24].…”

A universal automatic and self‐powered gate driver power supply for normally‐ON SiC JFETs

“…Silicon Carbide SiC power switching devices exhibit lower power losses, enable utilisation of high switching frequencies and can operate at higher temperatures (> 200 • C) compared to state-of-the-art silicon (Si) counterparts [1][2][3][4][5][6][7][8][9][10][11][12][13]. Today, SiC power metal-oxide-semiconductor field-effect transistors (MOSFETs) [14][15][16] and the SiC junction-field-effect transistors (JFETs) [17][18][19][20][21] are available with voltage ratings in the range of 650-1700 V. SiC JFETs can be designed as either normally-OFF or normally-ON switches.…”