Research In High-speed Communication Ring Network And Power Electronic Synchro-control Technique

With power electronic device technology,communication technology and control method progressing increasingly,a significant trend of modern power converting techniques has appeared towards developing the power electronic device which are’characterized by large capacity,modularization,intelligence,high power density,high reliability and maintainability.For large capacity complex power electronic systems,power devices,control variables and feedback variables,connection lines are numerous.The use of traditional centralized control mode will bring complex system structure,difficult configuration and lots of point-to-point connection lines,which make the system difficult to maintain,pose challenges for electromagnetic compatibility design.There are some problems in this area that need to be solved.Distributed large capacity converter system has high requirements on real-time performance,and it has distributed characteristics in control methods,power circuit structure,and space layout.The thesis has presented a distributed ring network topology for large capacity power electronic systems based on high-speed Ethernet.Referring to current common clock synchronization schemes for power electronic systems,a simple and convenient method for ring network is proposed.The clock synchronization algorithm includes full-synchronization process and self-synchronization process.It can compensate the initial deviation of the clock and the line transmission delay,and the crystal drift of different station clocks in real time.High clock synchronization accuracy can be achieved without clock error accumulation problem.For the needs of distributed system clock synchronization and synchronization control,this thesis has developed a communication protocol applicable to this ring topology,analyzed the application of Ethernet communication in power electronic systems.This thesis has described the composition of the data packet in the communication protocol in detail,introduced the software implementation of the synchronous control technology.This thesis has analyzed the working mode of distributed ring network topology based on high-speed Ethernet communication.The design of the nodes in the distributed system is studied.Key issues in the design of master and slave node are analyzed and studied.To verify the basic Ethernet function of the distributed ring network topology and the clock synchronization algorithm,a simple experimental platform has been built.The experimental results show the feasibility of the distributed ring topology and clock synchronization algorithm proposed in this thesis,and it also demonstrate the correctness and feasibility of the related technologies studied in this thesis.