Research On Control Technology Of Modular Long-wave Communication Power Supply For High Voltage Input

Input-series output-parallel(ISOP)combined system composed of multiple power electronic converter modules connected by input series and output parallel is often used in the occasions for high DC input voltage and high-power electric transform,such as urban rail transit,new energy distributed generation and some communication power sources.This kind of system has high requirements for stability and control technology.Taking the modular long wave communication power supply as the research object,this paper studies the its output current frequency accuracy for single module,output current synchronization and input voltage sharing for multi module.Firstly,according to the system design requirements,a set of 10 module input series output parallel long wave communication power supply is designed.Each module is cascaded by DC-DC phase-shifting full bridge circuit and DC-AC inverter power circuit.Then,at the single module level,the defects of the traditional look-up table method are analyzed,and a high-precision digital look-up table method is designed.By looking up the sine table,the algorithm can output the signal of any specified frequency in the range of0～300Hz,which solves the problem that the output current frequency accuracy is lost when the sampling points exceed or cannot be evenly distributed in the array interval.Secondly,at the system level,based on the problem that the output current signal is not synchronized when the output terminals are connected in parallel,the theoretical analysis of the output asynchrony caused by the error of active crystal oscillator is carried out,and then the detailed design process of digital synchronization algorithm is given,and the algorithm is promoted through the general formula and specific algorithm implementation process are given.Thirdly,at the system level,this paper first analyzes the imbalance mechanism of the system,discusses the stability of the system when the input voltage sharing and output current sharing strategies are adopted respectively,and determines the feasibility of the multi module input voltage sharing control strategy.Then,starting from the underlying principle,the voltage sharing control strategy is designed,and the control block diagram and the specific parameter design process are given.Finally,a 90 k W prototype with three modules is built for experimental verification.The proposed high-precision frequency look-up table method for single module,output digital synchronous control algorithm for multi module with parallel output and voltage sharing control strategy for multi module with series input are experimentally verified respectively,and the experimental results fully meet the requirements of the system,which verifies the effectiveness and important engineering application value of control strategy and the algorithm proposed in this paper.