Contoured Bode Plot based Robust Decentralised Controller for Three-Input Integrated Dc-Dc Converter

Abstract

Designing controllers for multi-input multi-output (MIMO) integrated Dc-Dc converter is complicated due to shared elements, integrated structure, and relation between the input and output variables of the converter. In this work, a robust PID controller based on a Contoured Robust Controller Bode Plot (CRCBP) is designed for control of the three-input integrated Dc-Dc (TIID) converter. This method combines robust control with classical loop-shaping. In this procedure, the outlines of the robust metric are drawn on the Bode charts of the controller, and the controller is adjusted till its frequency response does not cross the contours of the robust metric to meet the stability and performance goals. The TIID converter is modeled using state-space analysis and a Transfer Function Matrix (TFM) is acquired from the small signal continuous time model. The interactions between the inputs and outputs of the converter are quantified and input-output pairing is identified by Relative Gain Array (RGA). The input-output pairing suggested by RGA decides the controller structure. Further, the weight functions (loop-shaping filters) are designed based on the TFM which represents the desired robustness and performance of the controller. These weight functions are used to define the robust metric for the controller design. Based on this, the CRCBP controller is designed iteratively. A standard TIID converter of power rating 288 W with input voltage levels of 24V, 30V, and 36V is considered to show the effectiveness of the proposed controller under varying operating conditions. The real-time simulation results disclose the proposed controller's superiority over the existing approaches in the literature.