Sampled-data Modeling of PWM Boost Converters in Continuous and Discontinuous Inductor Current Modes

Abstract

When the boost converter operates in continuous and discontinuous inductor current operation modes, owing to the relatively more complicated nature of the boost converter with non-ideal elements, a parsimonious large signal and small signal model for this converter, with and without feedback, is lacking. In this work, a zero order hold (ZOH) equivalent sampled-data (discrete-time) model of the boost converter for computing its small-signal frequency response and closed loop behavior for both large and small signals is developed and experimentally verified. In this model, non-ideal conductive loss effects can also be easily taken into account in continuous and discontinuous inductor current modes. Frequency response computation technique from the model are developed and a Newton-Raphson technique is shown to accelerate the computation of the frequency response. Experimental evaluation of the predicted small-signal frequency response from the model is presented and the computational efficiency of the Newton-Raphson technique is evaluated. Using setpoint perturbations, the ability of the discrete model in capturing nonlinear closed-loop (PI) control performance is demonstrated with experimental confirmation