Research Of Input-Series-Output-Parallel DC/DC Converter Based On Dead-Beat Control

With the gradual integration of new energy power generation,the DC grid has developed rapidly.In the DC grid,the power electronic transformer as a power router is a key device in the DC grid.In particular,the DC/DC DC converter can provide a DC interface for the network side and the user side.Therefore,the DC/DC converter is selected as the research object.In high-power DC/DC converters,input-series-output-parallel topology is generally applicable to converter scenarios of high-voltage input,low-voltage and highcurrent output DC/DC.In order to improve the output quality and control performance of the system,the output voltage of the system and the output inductance current of each power module need to be strictly controlled.Furtherly,to ensure the stability of the system,it is necessary to maintain the transmission power balance of each power sub-module in the system.In this paper,a multi-module input-series-output-parallel DC/DC converter is applied in the high-power DC/DC conversion system,in which the power sub-module adopts a dual-transistor forward DC/DC converter topology.According to the characteristics of input-series-output-parallel DC/DC converter system,this paper adopts three-loop control strategy,which includes output voltage control loop,power sub-module output inductance current control loop and power sub-module input voltage sharing control loop.For the input-series-output-parallel DC/DC conversion system designed in this paper,firstly,the small signal model of DC/DC converter is established based on the small signal model of a single power sub-module,and the input-output transfer function matrix is deduced.Then,the modulation and control strategies adopted by the system are described in detail.In order to improve the output quality of the system and reduce the ripple of the output current,a interleaved phase-shift modulation strategy is adopted in the DC/DC converter system.At the same time,to improve the control effect of the system,the three-loop control adopted in this paper is introduced.Furtherly,to improve the control performance and the response speed of the system,a deadbeat control method based on the average inductance current is proposed in this paper.Finally,the simulation verifies the modulation strategy and control strategy.According to the relevant design standards and requirements,an experimental prototype of three-module input-series-output-parallel DC/DC converter is built.Firstly,the design principle and method of hardware parameters in DC/DC converter are described specifically.Then the design principles of the main circuit,control circuit,auxiliary circuit,heat dissipation,fault treatment and protection of the system are explained.Finally,the experimental waveforms and technical specifications of the prototype DC/DC converter designed in this paper are obtained through relevant experiments.The correctness,validity and practicability of the input-series-outputparallel DC/DC converter and its modulation strategy,control strategy and design scheme are verified.