State-trajectory Control of LLC Converter Implemented by Microcontroller

摘要

this paper investigates how to integrate statetrajectorycontrol functions of LLC resonant converter within acommercial low-cost microcontroller, including SimplifiedOptimal Trajectory Control (SOTC) for load transient, burstmode and soft start up. Simplified calculation process isproposed for SOTC to minimize digital delay. Guideline to selecta proper microcontroller is presented to limit calculation delayand ADC delay within 1 switching cycle to ensure good transientperformance. Optimized transient processes are proposed toeliminate large oscillation between burst mode and normaloperation. Soft start-up is implemented with sensing the outputvoltage only. The whole control system structure is proposed tointegrate all these control functions and for the first time allthese control functions are integrated in one low-cost MCU. Theresults are demonstrated on a 130kHz 300W 380V/12V halfbridgeLLC resonant converter with MCU TMS320F2808.