Robust nonlinear synergetic control for m-parallel-connected DC-DC boost converters

Abstract

This paper presents synergetic control design for an m-paralleled boost converter system under active current sharing. The presented design overcomes such problems of the system as multi-connectivity, nonlinearity, and high dimensionality. The set of macro-variables introduced during control design defines a set of invariant manifolds that accommodate different current sharing regimes such as master-slave and democratic current sharing simply by changing coefficients in the macro-variables. Invariant manifold formation contracts the system state space and makes it possible to perform stability analysis for an arbitrary number of paralleled boost converters. The stability analysis and current sharing analysis presented in this paper provide criteria for the choice of control law coefficients. The simulation results for a two-converter system validate the theory and show that the closed-loop system is characterized by stable operation, fast response, good voltage regulation, ability to nullify steady state error not only of output voltage but also of current sharing, capability to control the current drawn from each converter, ability to change current sharing during operation, and, most importantly, capability to withstand variation of the system parameters by 400%.