A Thesis Submitted In Partial Of Fulfillment Of The Requirements For The Degree Of Master Of Engineering

Energy shortage and environmental pollution is the common problems for everybody in this century, how to achieve energy conservation and environmental protection is the focus of today's world, and the technology of the medium voltage drives (MVDs) is one of the most effective methods to save energy, which gets a universal attention by a large number of research scholars. With the rapid development of the modern power electronics technology, the computer technology and the modern control theory, the MVDs has been developed rapidly and applied widely. But at the same time it has brought many new questions. In this paper, the internal fault of the diode-clamped three-level inverter is studied.In this paper, first of all, the background and the development of the MVDs are introduced, and then the meaning of its application is recommended. Then, the trend of the MVDs is presented simply, and then the research status and the significance of the fault analysis of the MVDs are introduced.Secondly, the topology of the diode-clamped three-level inverter is introduced simply, and then the function of the components of the diode-clamped three-level inverter are introduced, and then the basic principles of three-level MVDs is analyzed, which include the principle of the frequency control and the work principle of three-level inverter.In order to supply the hardware for the fault analysis of the MVDs, in this paper, the method of building the experimental platform is recommended in detail. Firstly, it describes the design and improve of the DC link topology, and then introduces the design of the filter, in particular, introduces the design of the power switching module's driver, and then studies the design of the power control unit used the DSP model TMS320F2812, at last, introduces the method of the pulse signal interlocking for the protection of the MVDs.The fault of the power switch module in the MVDs is studied. Firstly, the method of building the MVDs'model in the MATLAB simulation environment is introduced. In this simulation platform, the internal fault is carried out. The fault analysis is mainly abort the power switching module which cause fault easily. The fault of one power switching modules and two power switching module are discussed respectively, and then based on the difference of output voltage and current, the method of recognizing which power switching modules is fault is studied, and its feasibility is confirmed through the simulation and the experiment. Finally, the protection of the power switching module is studied simply.