Signal flow graph model and control of dual input boost converter with voltage multiplier cell

Abstract

The dual input boost converter (DIBC) with dual boost and integrated voltage multiplier cell (VMC) operating in continuous conduction mode (CCM) at duty cycles larger than 0.5 is a necessity to deliver a high voltage gain for energy systems possessing two independent renewable energy resources (RES). However, the modelling of this higher order converter is challenging due to the overlapping switching signals, multi-stage operation and the parasitic elements. Thus this paper aims to develop the small-signal transfer function model by applying the signal flow graph (SFG) approach. In addition, to handle the output voltage regulation of this converter with unknown load values this paper presents the design of adaptive current-mode (ACM) control using an adaptive law to estimate the uncertain load resistance in terms of load conductance to compute the reference inductor currents. Two independent input inductor reference currents are considered to ensure the decoupling among the interacting loops. The dynamic performance of the ACM controller to handle unknown load and an improved version of a traditional control, the feedforward plus feedback controller for known values of load resistance are designed and assessed. A 200W converter model is built, and the controls are implemented using FPGA.