Output-feedback control of interleaved Buck-Boost DC-DC power converter with continuous input current for fuel cell energy sources

Abstract

It is well known that the classic buck-boost converter topology draws pulsating currents from the power supply. These pulsating currents entail acceleration of the aging rate of the fuel cell. In this paper, we are considering a Buck-Boost DC-DC converter topology featuring continuous input current. The converter interleaved structure ensures substantial increase of power density compensating power losses related to the converter switching nature. The control objective is to enforce the DC-bus voltage to track its desired value despite load uncertainties and to ensure adequate current sharing between different parallel modules of the fuel cell interleaved Buck-Boost converter (FC-IBBC). The point is that the internal voltage of the fuel cell is not accessible for measurement and to minimize the number of sensors, a nonlinear output-feedback controller, constituted of a state-observer and nonlinear control laws, is designed on the basis of a nonlinear model of the FC-IBBC system. We formally prove that the proposed controller meets its objectives, i.e. DC-bus voltage regulation and equal current sharing. The theoretical results are well confirmed both by simulation, using MATLAB®/Simulink®.