Two-layer nonlinear control of DC-DC buck converters with meshed network topology

TL;DR

This paper introduces a novel two-layer nonlinear control approach for DC-DC buck converter networks with meshed topology, ensuring stability and voltage regulation under arbitrary load conditions.

Contribution

It proposes a new Lyapunov-based analysis and a distributed optimal controller for meshed converter networks, enhancing stability and voltage regulation capabilities.

Findings

Stable voltage regulation in meshed networks with arbitrary loads.

Distributed control achieves asymptotic stability.

Lyapunov function effectively analyzes current dynamics.

Abstract

In this paper, we analyse the behaviour of a buck converter network that contains arbitrary, up to mild regularity assumptions, loads. Our analysis of the network begins with the study of the current dynamics; we propose a novel Lyapunov function for the current in closed-loop with a bounded integrator. We leverage on these results to analyse the interaction properties between voltages and bounded currents as well as between node voltages and to propose a two-layer optimal controller that keeps network voltages within a compact neighbourhood of the nominal operational voltage. We analyse the stability of the closed loop system in two ways: one considering the interconnection properties which yields a weaker ISS type property and a second that contemplates the network in closed loop with a distributed optimal controller. For the latter, we propose a novel distributed way of controlling a Laplacian network using neighbouring information which results in asymptotic stability. We demonstrate our results in a meshed topology network containing 6 power converters, each converter feeding an individual constant power load with values chaning arbitrarily within a pre-specified range.