Feed-forward control of non-linear inductors providing soft-switching of DC-DC-converters

A novel auxiliary circuit with a current controlled non-linear inductor has been developed to achieve soft-switching for different converter topologies. This paper outlines the operation principle of the auxiliary circuit and gives details about the control of the non-linear inductor. A model has been developed that allows the calculation of the control current dependent on the operating point of the converter. This model has been implemented into a digital controller. A prototype converter has been built and tested to verify theoretical predictions. Measurements have shown that the efficiency of the prototype converter is greatly improved by the auxiliary circuit. Experimental results are in good correlation with theoretical prediction.