Average natural trajectories (ANTs) for boost converters: Centric-based control

The control of boost converters using traditional linear techniques features fixed switching frequency and a simple implementation. Due to its characteristic non-minimum phase behaviour, the dynamic response can be improved only to a limited extent. On the other hand, excellent dynamic performance can be achieved with boundary controllers in which the demands placed on processors and sensors are greatly increased. This work introduces a novel control technique for boost converters that combines pulse width modulation with geometrical analysis. The natural evolution of the converter averaged state variables is modeled in a geometrical domain, and employed to develop a non-linear control scheme. The proposed technique is suitable for implementation in low cost DSPs, using low bandwidth sensing stages, and it features fixed switching frequency, fast dynamic response, and low computational burden. These characteristics make the controller a very appealing alternative for high-volume applications. The issues related to the RHPZ in the small signal model of the converter are eliminated due to the geometric-based nature of the proposed control technique, and therefore fast dynamic response can be achieved. Furthermore, since the model developed predicts large-signal behaviour accurately, reliable and predictable behaviour can be obtained at any operating point. In this way, magnetic saturation and system failures can be avoided even during extremely large transients. The contributions made to the theoretical and applied field are valid for any combination of reactive components due to the normalized approach adopted. The theoretical concepts are supported by detailed mathematical procedures and the controller's implementation validated by experimental results.