A LLC Resonant Full - bridge Converter with Fractional Order PID Controller*

Abstract

This paper takes the controller of the LLC Resonant Full Bridge Converter as the design object. Firstly, using Extension Describing Function (EDF) to establish small-signal model of the converter and calculating the transfer function of the system to design the PID controller. Then the Particle Swarm Optimization (PSO) algorithm is used to tune PID parameters for the optimization control of the LLC Resonant Converter and verified by simulation, result showed that the system with PID controller has insufficient dynamic response ability and large ripple of the output voltage. So secondly, the Fractional Order PID (FOPID) controller is applied to the converter, using the same method to tune FOPID parameters. Finally, the simulation verified that using FOPID controller the converter has less ripple of the output voltage and it could supply with faster dynamic response, and the response speed might close to 2-4 times comparing with PID controller, so it can be applied to the occasions with large load change rate.