| Due to the switching of its semiconductor devices, a regulated energy-storage dc-to-dc converter (REDC) cannot be represented as a linear time-invariant system, rendering most analytic tools such as Bode plots, root locus plots, and Nyquist plots inapplicable. The technique of small-signal perturbation is often applied to extract a linear time-invariant model for an REDC. The validity of the small-signal frequency-domain model is quite limited because there are substantial errors generated from some of the steps involved in the derivation.A new simulation algorithm is presented in this dissertation for the accurate and efficient simulation of REDCs. The key features of the new simulation are the state-transition-matrix table-lookup approach to the solution of the differential equations describing an REDC, a modified binary-search algorithm to obtain an initial estimate of the switching instants, and a quadratic extrapolation for the accurate final determination of the switching instant. To fully exploit the valuable data generated from the simulation procedure, performance-index functions are proposed in this dissertation as a quantitative measure of the quality of the performance characteristic of an REDC.On a theoretical basis, the new simulation algorithm is about 50 times faster than existing simulation algorithms, provided the same order of magnitude of error is achieved by the different simulation algorithms. The superior computation speed of the new algorithm over existing simulation algorithms is also verified by measuring actual execution times taken for example problems. In addition, the accuracy of the new algorithm is reflected in the close agreement between simulated waveforms and measured waveforms in two different experimental regulated converters. By using a particular performance-index function as a design guide, improved transient response of an REDC has been obtained, substantiating the utility of performance-index functions.The topological complexity and the switching nature of an REDC inevitably requires that the study of such a system in the time-domain be accomplished through digital simulation. The lengthy computation time required by existing simulation algorithms and the lack of a concerted strategy in utilizing the simulation data are two major drawbacks to a study of an REDC through large-signal time-domain methods. |
