Dynamic characteristics of the push‐pull dc‐dc converter

Push‐pull dc‐dc converters are used widely as large‐capacity power supplies for electronic equipment. Previously, the authors have shown that when the transformer magnetizing current in this converter is not negligible, there are six modes of operation determined by the relation between the reactor and the transformer magnetizing currents. They have analyzed the steady‐state characteristics for each mode of operation. This paper considers the analysis of the dynamic characteristics for each mode of operation for small perturbations around the steady‐state operating point. Transfer functions for four of the six modes of operation were derived based on a new model with the ripples of the transformer and the reactor magnetizing currents taken into account; they were shown to be of the first‐order delay system. It turns out that in two of these four modes of operation the reactor current is continuous and by using these modes, a highly stable converter with small output voltage ripple for a relatively large load current can be realized.