Robustness Analysis and Controller Design Based on a Generalized Model of Nonisolated Multiphase DC–DC Converter

Abstract

The nonisolated multiphase dc-dc converter (NMDC) has important research value and broad application prospect in fields such as smart grid and new energy vehicles because of its high power density and low output ripple. However, with the increase of the phase number, the parameter inconsistency among each phase will make the NMDC model quite complex. Moreover, parameter uncertainty and quadratic nonlinearity in the small-signal model can degrade control system performance, leading to a big challenge in controller design. In this paper, the generalized robust control model and the method of robust controller designing of NMDC concerning parameter uncertainty and quadratic nonlinearity is developed. Firstly, parameter uncertainty is described by convex polyhedra model. Secondly, the Lyapunov theorem is applied to solve the linear and quadratic nonliearity of the control model. Finally, with the method of Linear Matrix Inequality (LMI) region pole configuration, the analytical solution of the control model is achieved. Based on the proposed model, the independent control of NMDC with reduced sensors, including current sharing, flexible power distribution and robust control of the NMDC are realized. Both simulation and experimental results verify the effectiveness of the controller. Compared with traditional controller, the controller proposed in this paper can be stable in more complicated working conditions, and has a faster adjustment time, suitable for multiple topologies as well.INDEX TERMS nonisolated multiphase dc-dc converter (NMDC), parameter uncertainty, quadratic nonlinearity, convex polyhedron, robust control