Small-signal stability analysis of power converters with optimal pulsewidth modulation strategies

Optimal pulsewidth modulation strategies are commonly used in power electronics applications with closed-loop controllers. However, there is a lack of specific studies in the literature that analyze and study the dynamics of these modulators, which makes it difficult to derive small-signal models for stability analysis and controller design. Moreover, in many studies, the influence of optimal pulsewidth modulation on the small-signal stability analysis is disregarded. This article addresses these issues by proposing a modeling methodology for optimal pulsewidth modulators, applied to a selective harmonic elimination modulator. The proposed methodology is based on the frequency response analysis, which is particularly convenient for controller design. The study shows that the classical zero-order hold model employed for carrier-based pulsewidth modulators is valid for characterizing the dynamics of optimal pulse-width modulation strategies. Simulation results validate this conclusion.