Frequency response analysis for DC-DC converters without small-signal linearization

Presented herein is a frequency-domain analysis approach using Matlab simulink models via fast Fourier transform (FFT) of DC-DC converter closed-loop systems without small-signal linearization. Two modeling techniques are used: 1) average large-signal model; 2) pulse-by-pulse switching. It is shown that the frequency response result obtained with the Matlab Simulink and PSPICE model using average large-signal technique is comparable. Moreover, contrary to using PSPICE, obtaining frequency response using FFT via the Matlab Simulink model with the pulse-by-pulse switching method is easy and straightforward. The reason is that Matlab can accommodate script files for repetitive simulation data processing, whereas PSPICE cannot. Frequency domain analysis on the dc-dc converter model using the pulse-by-pulse switching technique leads to a more accurate result since all nonlinear elements in the circuit are included. The proposed "software analyzer approach" is demonstrated and validated with a converter power system operating in the solar-array voltage regulation mode.