Feedback control of phase shift modulated half bridge circuits for zero voltage switching assistance

This paper develops concepts for feedback control of phase shift modulated half-bridge (PSM-HB) circuits for zero voltage switching (ZVS) assistance. Using a novel approach to determine the amount of ZVS assistance required, feedback control is applied to the PSM-HB in order to assist ZVS in half- and full-bridge based circuit topologies that are required to operate over a wide range of conditions. Feedback control of the PSM-HB allows minimum currents to be maintained at all operating points, allowing PSM-HB circuitry to be added to existing topologies with minimal additional losses. Practical considerations such as startup sequencing, an angle modulation strategy for fast auxiliary current changes, and auxiliary device selection are presented. Experimental results are presented for a 130 V, 200 W, 100 kHz dual active bridge demonstration system with an FPGA based implementation of the proposed approach. Together with existing literature, this paper aims to improve ease of design and implementation of PSM-HB ZVS circuitry when operating over a wide range of conditions with unknown or nonlinear circuit parameters.