Boost converter control using Smith Predictor technique to minimize the effect of Right Half Plane zero

Abstract

Stringent output voltage regulation with faster transient response is demanded for dc-dc converters. A boost converter is important in LED lighting, photovoltaic systems, hybrid electric vehicles etc. But the presence of a Right Half Plane (RHP) zero in the small-signal model of a boost converter for its continuous current mode operation restricts its speed of response. With standard fixed frequency control, the effect of a RHP zero cannot be eliminated completely. In this paper, the principle of Smith Predictor control is used to minimize the effect of RHP zero and maximize the achievable control loop bandwidth with sufficient phase margin. The Smith Predictor structure is realized with a Sallen-Key band pass filter and simulated with a voltage mode (VM) boost converter and a type III compensator in closed loop. The analytical results are verified with large-signal CADENCE switched simulations. The limitations of Smith Predictor control are also discussed in this context.