Research On The Technology Of Three-Phase Stacked Interleaved Buck Hydrogen Production Converter

The "14th Five-Year Plan" points out that the integration of hydrogen energy and renewable energy has become an important driving force leading the global energy transition to green and low-carbon.The green production of hydrogen energy has become a necessary prerequisite for achieving the goal of "carbon peak and carbon neutrality".In the process of hydrogen production by electrolytic water,the new energy voltage needs to be transformed into a voltage level suitable for the operation of the electrolyzer and to meet the requirements of low voltage and high current and low current ripple of the electrolyzer.This article proposes a three-phase stacked interleaved Buck converter and its regulation technology,which can effectively reduce the output ripple and prevent the current shock caused by the ripple from damaging the electrolyzer,which is conducive to the stable hydrogen production of the electrolyzer and the high efficiency operation of the system,mainly as follows:Firstly,using renewable energy hydrogen production systems as application scenarios,analyze and compare four types of electrolytic cells,select alkaline electrolytic cells as simulation load objects,and study their characteristics and technical indicators.And a classification and summary of the widely used DC hydrogen production converters and control methods were made.According to the electrical specifications of the electrolytic cell,a three-phase stacked interleaved Buck converter is proposed,and its control method is improved to better match the load characteristics of the electrolytic cell.Secondly,using the traditional 6-pulse phase-controlled rectifier method for reference,the IGBT high-frequency chopper is modulated with switching period interleaving of 60°.The modulation process,working mode and output ripple of the three-phase stack-staggered 60°Buck converter are analyzed in detail.It is calculated that the inductance current ripple of the converter is much smaller than that of the conventional staggered parallel two-level converter.Thirdly,an improved control strategy is proposed to meet the requirements of continuous current,low ripple,and low ramp rate in the electrolytic cell.The inner loop adopts the average value of in-phase current control,while the outer loop takes the average voltage of two electrolytic cells as the given current in the inner loop.Combined with semi physical real-time simulation,it is preliminarily verified that the output voltage of the converter is stable,with small overshoot,and can achieve good balance of inductance current,significantly reducing current ripple.Fourthly,in order to verify the correctness of theoretical analysis and the feasibility of the proposed control strategy,a hardware circuit and testing experimental platform for a three-phase stacked interleaved 60 ° Buck hydrogen production converter were built.The experimental results further verify that the output ripple of the converter can be effectively reduced,and the voltage sharing effect of the proposed control strategy is good,with high stability and efficiency.Through the dual verification of semi physical real-time simulation and hardware experimental platform,the results show that the designed converter and the proposed improved control strategy can achieve a true bipolar structure,output low voltage and high current without output ripple,and better match the characteristics of the electrolytic cell.