STEADY-STATE ANALYSIS OF PWM DC DC SWITCHING REGULATORS USING ITERATIVE CYCLE TIME-DOMAIN SIMULATION/

A new iterative technique for steady-state analysis of pulsewidth modu lated (PWM) dc/dc switching regulators is presented. The methodology i s based on transforming the closed-loop regulator into an open-loop co nfiguration, The steady-state solution is solved by two iteration leap s. The first loop is to find the steady-state state variables when the converter is at a fixed duty cycle. The circuit waveforms are obtaine d by a stepwise time-domain simulation method, which is based on using stepwise quadratic formulation of the circuit state variables with pr ogressive analysis of the switches' states. The second iteration loop is to determine the steady-state duty cycle of the PWM modulator outpu t, using an explicit ''fictitious'' ramp offset value as the error ind ex. This two-loop iteration approach lessens the occurrence of the non convergence problem that is sometimes found in the single-loop iterati on method. Furthermore, the advantages of this method include the foll owing: 1) substantial improvement in speeding up the convergence to st eady-state solution; 2) simplicity in requiring simple algebraic manip ulations; 3) generality in determining valid topology without prior kn owledge of the regulator operation; and 4) directness in determining t he switching instants. Several examples illustrating the computational efficiency and the accuracy are presented and are verified with the a vailable literature.