Some considerations about discrete-time AFC controllers

Resonant Control or Adaptive Feedforward Cancellation is a linear control technique dealing with periodic signals. It is based on the Internal Model Principle and let asymptotically track/reject periodic references/disturbances. Many papers studying resonators in the continuous-time domain have been published, nevertheless, the increasing use of microcontrollers motivates its discrete-time design; sampled-data control systems are a rich subject of study and discretizing resonators from continuous-time is not enough to take into account all the sampling effects. In this paper, a review of discrete-time AFC controllers is presented and some results of the classical continuous-time design techniques for resonators are translated into discrete-time.