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

In the high-power DC power supply system,compared with the traditional centralized power supply,the distributed power supply can form an N+m redundant power supply system through modular design,which improves the reliability and fault tolerance of the system.In this power supply mode,when the original power supply system expands or replaces some damaged modules,a replacement module(new system)needs to be introduced.Although the new system module is consistent with the original system module in terms of input,output and other index specifications,it is difficult for them to be consistent in terms of the equal flow control method and communication protocol as well,which will result in the normal equal flow coordination between the new system and the original s ystem.Therefore it is a noteworthy issue for how to adjust the output current adaptively between heterogeneous systems,so that the new system and the original system can work together and improve the service life of the power module.In this thesis,a feedback correction based on discrete consensus algorithm is proposed to adjust the coordinated current sharing control strategy of different systems.After the new system is merged into the original DC power supply system,the normal power supply of the entire system is restored to further improve the current sharing accuracy between different systems.Firstly,this thesis analyzes the important structure of the DC power supply system,selects the bidirectional Buck/Boost converter as the main circuit topology of the power module,analyzes the principles of its two working modes and designs the main circuit parameters.Then small-signal modeling of the modular parallel system is performed in both operating modes of the converter to derive the relationship between the DC bus,output current and duty cycle.Then Mathcad software was used to draw the Bode diagram of the parallel system before and after compensation according to the transfer function to verify the rationality of its closed-loop compensation network design.Secondly,in order to solve the compatibility problem between heterosystems of DC power supply,a heterosystem cooperative current sharing control strategy is proposed.Based on the current consensus algorithm in distributed communicatio n,the output current of the original module collected by the Hall sensor is data processed with the converged current value of the consistency algorithm to form the output current value of the system.Through the feedback correction of the equalization accuracy error,the output current value is continuously adjusted to improve the overall equalization performance of the heterogeneous system and ensure the stable operation of the whole system.The proposed control strategy is verified by simulation to ensure the normal operation of the DC power supply system after the integration of the new system and to achieve the output power balance between different systems.Finally,based on the theoretical analysis and simulation verification,the hardware and software design of the power module is carried out to complete the power module prototype mechanism.The proposed control strategy is experimentally verified,and the experimental waveforms are given after the new system is integrated into the original system for cooperative current equalization.The experimental results show that the control strategy can realize the alternative module system to work with the original system and improve the system equalization accuracy.