Frequency response analysis for power conversion products without small-signal linearization

Presented herein is an accurate approach for combining large signal modeling and frequency-domain analysis of a closed-loop DC-DC converter power system without small-signal linearization. The approach provides a high-fidelity solution for the converter's frequency response due to the inclusion of all non-linearity and parasitic effects and is applicable to both pulse-by-pulse switching and average large-signal models of DC-DC converters. In control-oriented simulators, fast Fourier transformation (FFT) is applied to the converter responses, being uniformly sampled for one period of each injected small signal. In circuit-oriented simulators, fundamental frequency components are extracted out of the converter time-domain responses that are usually simulated in a variable time-step mode. This simple, direct, and accurate analysis approach is critically needed for performance evaluation of the converter system frequency response and design validation of the converter closed-loop systems for which the linearizable large-signal models are not available. The "virtual network analyzer" approach provides an increase in the fidelity of non-linear and parasitic effects within the controller and converter's power stages for which the 'as is' non-linear pulse-by-pulse switching model is directly simulated. The frequency response analysis approach was validated with a converter power system operating in solar-array voltage regulation mode.