Determination and Implementation of SiC MOSFETs Zero Turn-off Loss Transition Considering No Miller Plateau

Realizing zero turn-
off
loss (ZTL) of SiC
mosfet
s in zero voltage switching (ZVS) power converters will further break the limitation of the switching frequency and push for higher power density. However, quantitative models analyzing ZTL phenomenon were not revealed in state-of-arts and the assumptions of switching transients under ZTL were not correct. Current ZTL implementations either have limited application range or sacrificed transition speed. To overcome these limitations, this article proposes an improved determination criterion considering no Miller plateau for an accurate prediction of ZTL and its boundary based on the Miller's theorem. A more accurate multicurve parameter extraction approach is presented combining the C-V curve with the gate charge and transfer characteristic curves for parameters extraction under dynamic switching transients, further improving the ZTL determination accuracy. For ZTL implementation, a novel approach of coadjustment of gate and channel current based on the gate charge compensation is first proposed, with advantages of wide adaptive range and high d
v
/d
t
. Experiments show the quantitative determination of the ZTL boundary has prediction error of less than 9.5%. It is also verified that the proposed ZTL implementation can reduce the turn-
off
loss up to 81% with only 20% increasement in the drain-source voltage rising time at ZTL boundary transition. The proposed implementation is also capable to adjust d
v
/d
t
based on demand with adjustment error less than 7.2%.