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An algorithm is presented for the efficient and accurate been reported, examples of which are given in [10]-[12].simulation of switched-mode piecewise-linear systems, a subclass of The simulation methods in the various investigations rewhich includes regulated energy-storage dc-to-dc converters. Three key features of the new algorithm that lead to significant improvements in ported toldteohave usedinter ation s that fin computational efficiency and accuracy are 1) a state-transition-matrix numerical solutions to the diferential equations that detable-lookup scheme to solve differential equations describing the sys-scribe the converter system by advancing through the sotem, 2) a modified binary-search strategy to obtain an initial estimate lution in sufficiently small time steps to achieve a modof the instant at which the system topology switches, and 3) a quadratic erate accuracy. There are two major limitations to existing extrapolation for the accurate final determination of the switching in-... -a . s stant. The computational efficiency of a program using the new algorithm is demonstrated by comparing its execution time with that of a The first is the lengthy computation time required to simprogram employing a standard fixed-step-size integration algorithm. ulate a transient induced by a sudden change in input voltThe accuracy of the new algorithm is verified by comparing results age or in load. In many present-day converters, it is not obtained from the simulations with results obtained analytically, and unusual that 500 or more switching cycles are required by comparing data from the simulation of two different regulated con-before a transient subsides and the new steady-state opverters with data measured experimentally. erating point is reached. To achieve a reasonably accurate simulation, an optimistic estimate is that 100 or more in-I. INTRODUCTION tegration steps are necessary during each switching cycle.SINCE the early 1970's, a great deal of attention has These two conditions together make for lengthy compubeen given by various authors to the subject of small-tation times. The second limitation is in the error created signal frequency-domain modeling of regulated energy-in determining the instant at which the power switch of storage dc-to-dc converters [1]--[9]. Even though there are the converter power stage should be switched ON or OFF.subtle differences among the individual approaches of With a finite integration algorithm step size, an uncerthese authors, the basic idea centers on the development tainty exists about the instant at which the switching is to of a perturbational model that is valid in the neighborhood take place. of an operating point which is fixed by the values of the A new algorithm for simulating the transient behavior converter components, the supply voltage, and the load. of converters in a computationally efficient manner is preSince the resulting small-signal model represents a linear sented in this paper. The simulation approach follows the time-invariant system, the famili...

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Four modes of operation are possible for the basic push-pull current-fed converter. Each mode is analyzed, circuit waveforms are explained, and relationships that influence the converter design are developed. Various design options and selec tion guidelines are presented along with experi mental results.