Author: Chou, Yuk-wah
Title: Fuzzy control methodologies applied to power converter control
Degree: M.Sc.
Year: 1995
Subject: Switching power supplies -- Automatic control
Fuzzy systems
DC-to-DC converters
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Pages: ix, 107, [28] p. : ill. ; 30 cm
Language: English
Abstract: Switching Mode Power Supplies (SMPSs) are complex plants to be controlled, with nature of non-linearity or time varying behaviour caused by changing switching topology, circuit parameters variations, and external disturbances. This thesis was an investigation of Fuzzy control algorithms for the control of Switching dc-dc converter, and addressed the application of fuzzy reasoning with imprecise, uncertain, and inexact information analysis for SMPSs. In this thesis, the following were achieved: 1) A Fuzzy control design methodology for the control of SMPSs was proposed, with control algorithm handling inexact nature of SMPSs. Rule derivation technique with completeness, interaction, and consistency analysis were addressed. 2) A Fuzzy PID control algorithm was proposed, with linguistic rule describing error, error sum and derivative, for generating controller output. This was a modification of conventional PID controller, and illustrated better closed-loop system performance. 3) By application of linguistic approximation on states, input voltage disturbance of SMPS, a Fuzzy feedforward-feedback algorithm was derived as an alternative control scheme. Better rejection to input voltage disturbance could be achieved, with acceptable system transient behaviour being observed. 4) Quasi-linear modelling technique on switching converter cell was investigated, and with control algorithm emphasized on "varying" operating point in reduced variable space. Adaptive Fuzzy quasi-linear control scheme was suggested, which would eliminate on-line extensive controller parameters calculation, and would modify the controller feedback parameters using fuzzy reasoning on quasi-linear model and quasi-linear state operating point. 5) Regarding to items 2, 3, and 4, a simulation software was also developed for the study of Switching dc-dc converter using larger signal converter cell behaviour analysis. Another Fuzzy Rule Base compiler was used for rule compilation generating quantity controller action values. This software integrated the control algorithms of Conventional PID, Conventional linear state feedback, Fuzzy PID, Fuzzy State feedback, and Fuzzy Quasi-linear adaptive schemes. These proposed Fuzzy algorithms were applied to a Buck-Boost Converter. Simulation results were presented to illustrate various aspects of the controller schemes. Performance was studied and compared with conventional controller.
Rights: All rights reserved
Access: restricted access

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