A technical report published in IEEE Transactions on Power Electronics, demonstrated that the switching loss of SiC MOSFET can be completely eliminated under some control strategies.
The study was conducted by Prof. Alex Q. Huang’s group at University of Texas at Austin and Prof. Bo Zhang’s group at University of Electronic Science and Technology of China. They analyzed the switching processes by TCAD simulation and found that the traditional method used to measure switching loss underestimates the turn-on loss and overestimates the turn-off loss due to discharge/charge current for MOSFET output capacitance (Coss) could not be directly measured.
The authors showed that zero switching loss (ZSL) is achieved when utilizing zero-voltage switching (ZVS) turn-on to recover the energy stored in output capacitance (Eoss) and using stronger gate driver and reducing parasitic capacitance to achieve zero turn-off loss (ZTL). With ZSL, the power loss caused by switching will no longer be the frequency limitation of system and this result has been verified in their experiment. In other words, the predominant factor that limits the upper boundary of switching frequency is not switching loss anymore, they are instead other frequency dependent losses such as magnetic core/winding loss, driving loss, and the minimum deadtime required to achieve ZVS.
