A modified integral pulse frequency modulator in control systems

Many recent works are concerned with theoretical problems and engineering applications of integral pulse frequency modulation in control systems. It has been shown that a control system in which an integral pulse frequency modulator (IPFM) acts as an error modulator is not, in general, asymptotically stable, and the ultimate motion takes the form of irregular oscillations. By appropriate setting of modulator parameters it is possible to decrease the amplitude of limit oscillations, buthis results in poor system dynamics. Here, a modified IPFM is proposed in which the threshold level is a function of the time interval between succeeding pulses. This modulator retains the noise immunity of a usual IPFM with improved dynamic performance.