Design of feedback laws for DC-DC converters using- modern control theory

The use of a canonical state model for DC-DC converters keeping track of the physical variables allows naturally to use state feedback compensation (usually called "modern control theory"). The injection of the state variables in the compensator gives a schematic control structure which implicitely includes multiple loops. In the case of classical cells and neglecting the equivalent switching delay of the modulator, complete state feedback may be used ; it is then possible to determine completely the bandwith and damping of the controlled cell, adjusting correspondingly the gains of the state compensator. Generalisation of these techniques for more general cases can be achieved using specific algorithms. For steady state accuracy, it is interesting to add an integral term. It is proved that its destabilizing effect is negligible under certain conditions.