Digital Power Supply Base On Current Predictive Control

With the development of technology,power supply has a wide range of applications in all walks of life.The current power supply generally adopts the two-level structure scheme,including the for mer PFC part and the latter DC/DC part.The former PFC part usually adopts the average current con trol,which is very mature at present,whether it is digital control or analog control.However,in rece nt years,with the focus of research on miniaturization,high-frequency,and low on-off loss,this topol ogy seems to be unable to meet the requirements.Therefore,Totem PFC has been widely used in vari ous analog and digital power supplies.The DC/DC part of the latter stage uses the half-bridge LLC,which is also widely used at present because it can work in the ZVS state and has low on-off loss.This paper introduces the research background and development status of Totem PFC,analyzes the small signal model of its operating mode,current loop and voltage loop.Based on this,a simplifi ed current predictive control with integrator is proposed,which has low THD,almost zero tracking e rror,wide load range and high operating frequency.The working principle of the half-bridge LLC co nverter is analyzed,its equivalent model is analyzed by fundamental wave analysis method,and the voltage gain curve is obtained.The small signal model of the half-bridge LLC is systematically deriv ed by using the extended function description method,and its transmission function in different state s is analyzed.The reason why the compensator is difficult to design is explained in this paper.By thi s method,the power level transmission function of the half-bridge LLC is reduced to eliminate a pair of poles on the transmission function,which can effectively improve the dynamic response capabilit y.The simulation software Matlab is used to verify the system parameter design and control princi ple,and the average current control and the Totem PFC simulation model with integrator are built res pectively,and the performance of the two is compared.Simulation models of single-voltage controlle d half-bridge LLC and time-shift controlled half-bridge LLC were built to test their dynamic respons e capabilities.The results show that both Totem PFC and Half-bridge LLC have significantly improv ed the working effect and dynamic response of this scheme.Based on this,the software and hardware of the system are designed.STM32G474 RE is used as the main control chip to design the power level circuit,sampling circuit,fault detection circuit,zero crossing detection circuit and driving circuit of the system.The experimental platform of Totem PFC and Half bridge LLC is built,and some of its main waveforms are tested to verify the correctness of t he design.