Development Of High Power Conversion System With Three Phase Input

In the high power applications, three phase voltage is usually used as the input. This thesis focuses on the development of a test system power supply with three-wire three-phase voltage input. The system should have the characteristic such as high power density, high reliability, good maintainability and multi-moniting functions.Based on the requirement, the system structure and the adopted techniques are determined. Though the analysis, it is found that the key issues of the system design lie in the implemention of the high reliability DC/DC modules and the design of the system back PCB board.The DC/DC module based on PSFB converter is the most important part in power converter system. The reliability of the adopting packaging techniques and interconnection techniques makes the design of the power circuit to be an important factor for the reliability. The key technique of high efficiency PSFB converter includes two: one is the soft switching technique, and the other is the voltage clamping technique of rectified diodes. A lot of applications testify the effectiveness and the reliability of the soft switching technique. As a result, the voltage clamping technique of the rectified diodes becomes a key point of the research. In the currently clamping scheme with two diodes, the clamping diodes turn off with serious reverse recovery when the converter operates in discontinuous current mode (DCM), which does influence the reliability of the converter. In order to overcome this problem, a novel voltage clamping scheme with current transformer is proposed in the thesis. The clamping diodes can turn off naturally for the full load range results in the improvement of the reliability. The conversion efficiency can be also increased with the proposed voltage clamping scheme. A 1.2kW, 40.67W/inch3 DC/DC module based on the new voltage clamping scheme is designed and built in lab, 1% can be improved compared with the original converter.In addition, the coordination of many function modules, the transmission of mass signals and the requirment of the expansibility and interchangeability make the design of the back PCB board to be another difficult point. The design procedure and the realization method are given in the thesis detailedly. At last, the power converting system is developed successfully.Finally, the clamping scheme is derived further and a new phase-shifted full bridge converter with secondary clamping scheme is proposed, with the output voltage as the clamping voltage source. The working principle is validated by the simulation results. The analysis proves that the proposed clamping scheme is a general voltage clamping scheme.