On the gain margin improvement using dynamic compensation based on generalized sampled-data hold functions

This paper shows that the use of dynamic compensation based on generalized sampled-data hold functions (GSHF) can arbitrarily improve the gain margin for continuous-time nonminimum phase linear systems. The GSHF compensator is a particular periodic digital controller. The effect of sampling period on the gain margin is analyzed. Furthermore, it is proved that under a mild condition, the gain margin improvement can be achieved without forcing the sampling period small. An important advantage of periodic compensation over LTI compensation is found to be the capability of reducing conflict between gain margin and sensitivity