Research On Control Strategy Of Input-Series Output-Series DC-DC Converter

In recent years, parallel technology standard module have many researches and applications. Standard modular series parallel include the following four categories: (1) Input-parallel Output-parallel System; (2) Input-parallel Output-series System; (3) Input-series and Output-parallel System; (4) Input-series Output-series System. The above four kinds of structure of standard modules can be composed of inverter, rectifier, Frequency converter and DC-DC converter, standard modules are connected in series or in parallel not only reduce power device electrical stress, it can improve system redundancy and reliability. With a large number of new energy development and utilization, DC-DC converter in wind power, solar photovoltaic power generation, electric vehicles and other new energy more and more applications. The Input-series Output-series DC-DC converter system is suitable for occasions of higher input voltage and output voltage, especially in the DC power supply, through the ISOS DC-DC converter to improve the voltage so as to achieve the corresponding voltage level.This paper analyzes the isolated DC-DC converter topology structure and control method, selected for the phase shifted full bridge converter stator module, sub module input port and the output port are connected in series to form an ISOS DC-DC converter, analysis and performance characteristics of the operating modes of the converter and the small signal modeling of the system. Through the relationship between the ISOS DC converter input current, input voltage and output current, output voltage, thus it can be seen that the control input voltage sharing and output voltage sharing can guarantee the normal work of the system, from the input voltage or output voltage adjustment for covariates as the breakthrough point, design a ISOS system control strategy, effects of system each module device parameters does not match the input and output voltage analysis and docking down control strategy design to provide theoretical basis.In this paper, a new type of linear droop control strategy, the control method for sampling the output voltage of each module's input voltage and system, each module of the system output voltage was drooping linear regulating characteristic, through each module input voltage and the reference signal and the system output voltage superposition error signal by sampling, operational amplifier, than the equivalent final adjustment of the accounting for the empty than it is to change the input voltage, so as to achieve the effect of adjusting input and output pressure. This control strategy makes each module have independent control circuit and without any link between the system, the system can achieve the independent work and modular design of the system, improve the system redundancy, reliability and scalability. According to the control strategy diagram, the stability of the control strategy is analyzed, and the range of the PI regulator is determined by drawing the root locus diagram to verify the stability and validity of the droop control strategy. In the MATLAB platform to build to ISOS phase-shift full bridge DC/DC converter is the core of the simulation model, and the sagging linear control strategy to simulate, validate the control strategy is correct and effective of; when the device parameters of each module in the system does not match, simulation results show that the control strategy can influence the accuracy of the input and output voltage adjustment, and further verify the stability and feasibility of the droop linear control strategy.