A New DC-DC Converter for Server Power Supply with Fast Dynamic Response

Abstract

The DC-DC converter for server power supply requires wide range of the input voltage and load variation, and it ought to have long hold-up time when power failure, therefore, this paper takes LLC Resonant Full-bridge Circuit as the base topology to design DC-DC converter. Firstly, using First Harmonic Approximation (FHA) to calculate the resonant parameters of the converter, and using Extension Describing Function (EDF) to establish small-signal model. Secondly, applying the Fractional Order PID (FOPID) controller and using the Particle Swarm Optimization (PSO) algorithm to tune FOPID parameters for the optimization control to solve the problem that the dynamic response ability and the ripple of the output voltage of the LLC resonant full bridge converter cannot be sufficient for the server power supply, meanwhile, the integer order PID controller is designed in the same method for comparison. 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 speed might close to 2-4 times comparing with PID controller, it indiciates that the system is more stable and it could satisfy the most requirements of the server power supply.