IMPLEMENTING ADAPTIVE DIGITAL CONTROL ON AN EXISTING LLC DC-DC RESONANT CONVERTER

In this paper, the implementation and design process of integrating an adaptive digital PID control scheme on an existing 650W LLC DC-DC resonant converter is presented. The objective is to improve the converter's dynamic response while maintaining adequate gain and phase margins over several different operating ranges and to improve the converter's ability to reject the 120Hz disturbance produced from the AC line source. The small signal models of the converter are obtained using MATLAB's System Identification Toolbox, which estimates a mathematical model based on the empirical uncompensated loop-gain frequency response data collected either from PSIM simulation or from the physical converter using a Venable frequency response analyzer. Compensator designs are based on the estimated models and digital control is performed using a TMS320F28035 digital signal microcontroller. Simulation and experimental results are presented which validates the estimated model and the compensator design process. The adaptive compensation control performance is compared to a typical single compensation controller to show the performance advantages.