access icon openaccess Fuzzy frequency-selecting sliding mode controller for LLC resonant converter

This is an open access article published by the IET under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/)
Received 26/11/2018, Accepted 04/12/2018, Published 21/01/2019

A fuzzy frequency-selecting sliding mode controller for LLC resonant converter is presented here. Based on the fixed high and low switching frequency of sliding mode controller in the LLC resonant converter, the fuzzy controller is used to generate the corresponding high and low switching frequency according to different power levels. The high or low switching frequency is then selected by the frequency switching signal generated by the sliding mode controller, thus the fuzzy frequency-selecting sliding mode controller is realised. The fuzzy control rules here come from the simulation and artificial summary of the application circuit and load characteristics, and the high and low switching frequencies varied with the load are generated by the fuzzy frequency-selecting sliding mode controller, so as to realise the stable control of the output power of the LLC resonant converter. The fuzzy frequency-selecting sliding mode controller for LLC resonant converter is applied to a 240 W all-digital adaptive dimming power supply prototype, which can effectively reduce the steady-state error of the output power of the LLC resonant converter, and has a consistent low ripple characteristic when the load changes.

Inspec keywords: control system synthesis; switching convertors; resonant power convertors; fuzzy control; variable structure systems

Other keywords: low switching frequency; LLC resonant converter; fuzzy frequency-selecting; fixed high switching frequency; fuzzy control rules; corresponding high switching frequency; sliding mode controller; high switching frequencies; low switching frequencies

Subjects: Control system analysis and synthesis methods; Power convertors and power supplies to apparatus; Control of electric power systems; Fuzzy control; Multivariable control systems

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