| In recent years, as the fast development of global data traffic, the power consumption of ICT (Information and Communication Technology) equipment also increases rapidly, so it is very necessary to build a data center with reasonable power supply system. The high voltage DC supply system has captured a lot attention for its simple system structure, low transport current and high efficiency, which has a bright future. The high frequency operation of the DC/DC converter can reduce the volume of the magnetic part in the power supply system effectively, which is very meaningful to improve the power density of the high voltage DC power supply system. So this thesis focuses on the high frequency DC/DC converter for data center application.This thesis reviews the background of high voltage DC power supply system for data center and the basic functions of different modules inner system. The characteristics of the next generation high voltage DC power supply system, the application of resonant circuit in high voltage DC power supply system and the excellent characteristics of the new type wide band silicon carbide semiconductor device are also introduced in this thesis. Then, the model of resonant converter is derived according to the method of First Harmonic Approximation (FHA). The gain curve and the factors that influence it are also studied. And the circuit modal is analyzed when the switching frequency of the resonant converter is slightly lower than the resonant frequency. The soft switch mechanism of the LLC resonant converter and the basic requirements to achieve soft switch are analyzed in detail.Next, the design optimization of DC/DC converter is also introduced in this thesis. The main circuit is designed when considering the application of high voltage DC supply system in data center, which include the selection of the main components and the optimization of magnetic components. And the drive circuit of silicon carbide MOSFET is designed when considering the characteristics of the silicon carbide MOSFET device, the reliability of the drive circuit and the requirement of high frequency. And the loss analysis is carried out in this thesis to evaluate the performance in power transportation.At last, the operation principle of the DC/DC resonant circuit is verified by simulation and experiment. The circuit is tested by the Power electronic simulation software Psim and the result shows that the circuit model analyzed in previous section is basically accurate. Then a high frequency LLC resonant converter with800V to400V,1.7kW output prototype is built to verify the analysis. The soft switch and the isolation of the primary side and the secondary side are realized and the highest efficiency is98.5%under550kHz. |
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