Closed-loop sampled-data error model for PWM DC/DC converters with input variations

This paper proposes an extended sampled-data error (small-signal) model of closed-loop Switched Mode Power Supplies (SMPS) operated with Pulse-Width Modulated (PWM) signals. This model includes a formulation of the input-to-state sensitivity matrix as well as support for non-linear ramps in expression of the switching conditions. A practical implementation of this model is derived for a Buck DC/DC converter operating in Discontinuous Conduction Mode (DCM). Transient simulations of both proposed model and piecewise-linear (PWL) system are performed, in order to check validity and performance of sampled-data error-model with respect to input variations. Output impedance also is derived from the proposed model, and compared with PWL model simulations.