Analysis and Design of Pulse Ratio Modulated Feedback Control Systems

An exact method of analysis is presented for a class of pulse-modulated feedback control systems which can be modeled by a multiple-loop nonlinear feedback system. The nonlinearity has a hysteresis characteristic. By means of the Tsypkin-Hamel criterion, suitably modified, a set of equations is obtained, determining the switching frequency, duty cycle, and steady-state dc error. Based on the graphical form of these equations, a design procedure is set forth. Specific cases have been examined and peculiar phenomena are evidenced; experimental data verify both the chosen model and the suggested procedures. A simplified pulse ratio modulator is also presented.