Research On Cooperative Current Sharing Strategy Of Different Systems In Distributed DC Power Supply

In DC power supply system,it is common to use building block converter modules in parallel.And spare modules are usually prepared to ensure the reliability of the power supply system.However,when the original modules fails without spare modules,how to integrate other alternative modules into the system is significantly important to maintain the stable operation of the system.The substitute modules mean a different system for the original system.Furthermore,the internal circuits and parameters of the power modules of the original system are generally unknown,similar to the black box,and difficult communications between the substitute modules and the original module system limits the integration of the new power modules into the existing system.Therefore,it is urgent to realize the adaptive adjustment of the different system and make the substitute modules cooperative operation with the original modules,and then expand the scope of application of the substitute modules.Given this problem,this thesis proposes a progressive optimization coordinated control strategy.After the substitute modules are incorporated into the original system,on the premise of ensuring the DC power supply system to return to normal operation,it further adjusts the current sharing accuracy of the system,optimizes the operation effect,and realizes the cooperative operation of different systems.Firstly,for the architecture of DC power supply system,the converter topology of power module with its main circuit parameters was selected.On the basis of the small signal modeling of the module parallel system,we designed the loop compensation of the converter,to ensure the stable work of the power modules.Then the overall performance of the designed power module was verified through the simulation.Secondly,in order to solve the problem of cooperative operation among different systems,this thesis proposed a progressive optimization coordination control strategy,which was divided into two stages: rough tuning and fine tuning.The rough tuning stage used step approach control,in which the bus voltage returns to normal after the current reference value of the substitute module is tentatively changed by the class dichotomy.This process simulated the thinking process of approaching the optimal solution step by step based on the bus voltage value.The fine adjustment stage used cooperative optimization control.To overcome the difficulty of informational encapsulation,the rough values of the output currents of the original modules were collected with the help of the non-contact Hall current sensor and the wireless transmission technology,and then the current reference values of the replacement modules were adjusted in order to optimize the operation effect of the system.This strategy can not only ensure the normal operation of the DC power supply system,but also realize the balanced output of modules between different systems,as well as control the current sharing accuracy of the sy stem and enhance the stability of the system.Finally,the simulation model of DC power supply system was built in MATLAB environment to verify the control strategy.Based on theoretical analysis and simulation verification,we designed the hardware and software of the power modules,made the prototype of the power modules and built the experimental platform of the module parallel DC power supply system.The results demonstrated that the control strategy could realize the cooperative operation between the substitute module system and the original system,control the current sharing accuracy of the system,solve the limitation of the system to the substitute module,improve the reliability of the system and expand the scope of application of the substitute module.