Two-stage PFM control

Pulse frequency modulated (PFM) control, thus far primarily used in step motors and attitude control systems of space vehicles, is gaining more and more significance as a natural, failsafe link between the "intelligent" and the "dynamic" part of general process computer control systems. However, no analytical design methods of practical relevance have been available so far. This paper describes a method for the analytical design of PFM control systems. This method is based on a new mathematical model of the PFM controller introduced by Frank in 1979 [6]. A "two-stage" configuration for the implementation of the PFM controller is proposed.