Using SPICE to model the dynamic behavior of DC-to-DC converters employing magnetic amplifiers

SPICE-based models using the technique of in-circuit averaging are used to study the small and large-signal characteristics of buck-type converters using magnetic amplifiers for regulating an auxiliary output. Detailed models have been provided for two cases: when voltage-mode control is employed as the technique for setting the main switch duty cycle, and when current-mode control is employed with primary-current sense. These models, when implemented for use with SPICE, support a circuit-oriented approach to studying a problem that is cumbersome to analyze using analytical techniques. Simulation results are presented to illustrate a few of the types of analyses that can be performed and also to show the different cross-coupling characteristics between voltage and current-mode control.<>