| Abstract |
A nondissipative snubber has been used to reduce the switching power loss in a PWM buck converter. The snubber consists of one inductive element, two capacitive elements
and three diodes. It has been established that a fixed relationship between the snubber component values provides the best snubber performance. Optimized design of the
nondissipative snubber is therefore reduced to the problem of selecting a snubber capacitor value in order to minimize the total circuit power loss. A large snubber capacitor will provide
the lowest switch dynamic power loss. Unfortunately, a large capacitor also leads to increased residual power loss in the snubber components, particularly in the snubber diodes. An optimum snubber capacitor value, therefore, exists which minimizes the combined residual snubber loss and the switch dynamic loss. An analysis of the nondissipative snubber circuit is described leading to a design process
which determines the optimum snubber component values. These values are found to depend upon the transition characteristics of the power switch. Optimum snubber designs
have been produced for ultra-fast, fast and standard IGBT power switches. The total power loss of these IGBT devices including the optimized snubber has been compared in a particular 2.2kW power converter topology. |
