Further reduction of switching loss for the lossless snubber based converters

Minimized gate resistance of the power device driver is presented for the further reduction of switching loss to the passive lossless snubber based converters. In the passive lossless snubber based converters, the di/dt and dv/dt are separately suppressed by the auxiliary inductor and snubber capacitor. So they are almost kept constant with the reduction of gate resistance, which will improve the switching speed and further reduce the switching loss. Thus the gate resistance can be reduced to the minimum that is much smaller than the value given in the datasheet. The operating principles are analyzed in detail and parameters of the passive lossless snubber circuit are calculated in this paper. Then the additional loss of passive lossless snubber circuit is analyzed and the switching loss is calculated. At last, the prototype of Buck converter with the passive lossless snubber is built and both hard-switching and soft-switching are experimented for comparisons. The results show that the switching loss can be further decreased with the reduction of gate resistance in the passive lossless snubber based Buck converters and efficiency can be improved.