Identification of a Hammerstein model for DC/DC converters operating in CCM

Abstract

This paper deals with a method for identification of a Hammerstein model of DC-DC converters operating in continuous conduction mode (CCM). This model has the duty cycle and the output voltage as input and output, respectively; it consists of a static nonlinearity and a linear and time-invariant model. The aim of the modeling the system by means of a Hammerstein model is due to its capability of describing the converter in a range of steady-state operating points instead of a desired well defined operating point as occurs for the small-signal models which are the more common mathematical description to approach the study of the converters themselves. The nonlinear characteristic of the Hammerstein model is constructed by determining a certain number of its input-output couples using the results of measures carried out at the steady-state for constant inputs. The linear model is identified using results of a transient corresponding to a suitable two-values PRBS sequence whose values are chosen among the above input-output couples of the nonlinearity. The identification of the Hammerstein model is carried out using experiments carried out in PSpice environment.