ESBT#8482; in high voltage fly-back converters

摘要

Optimizing the trade-off among the forward voltage drop, the breakdown voltage, and switching speed has characterized the development and the introduction of new power actuators in the field of high-voltage, low- and medium-power applications. Recently introduced in the market the ESBT™, whose name stands for Emitter Switched Bipolar Transistor, represents a new family of power actuators, particularly suitable for high voltage high switching applications. After a brief introduction on the emitter switching theory and its evolution from discrete to integral solution, this paper shows all the aspects related to efficient base driving methods, thus providing useful information to the designers of power converters. Thanks to its higher breakdown voltage capability and lower conduction losses, the ESBTs can be successfully employed in Fly-back converters widely used in 3-phase auxiliary power supplies. A new 1500V/8A ESBT has been tested in a 150W off line fly-back power supply working in mixed mode: particular importance has been given to the slope compensation needed to remove the sub-harmonic oscillations when the duty cycle is higher than 50%. Experimental results have been finally carried out showing the benefits offered by ESBTs in this application. Comparative measurements with high runner power Mosfets have also been reported.