An overall study of the asymmetrical half-bridge with unbalanced transformer turns under current mode control

Abstract

An overall study of the asymmetrical half-bridge (AHB) with unbalanced transformer turns under current mode control is presented. An analysis is presented for the output filter, switch stress, and dynamics. In addition, key ideas of the AHB transformer design are presented. This is followed by a survey of the existing methods that the AHB uses to achieve zero voltage switching at turn-on, namely the series inductance method and the parallel inductance method. Following these, the auxiliary L-C-C circuit method is proposed for the AHB to further minimize switching loss. Experimental results are included for a 48 V/5 V prototype operating at 6 A load and 400 kHz.