Research And Application Of A Novel Bidirectional DC/DC Converter

With the rapid development of new energy power generation technology and other green power, because of its small size, light weight, high conversion efficiency; the bi-directional DC/DC converter which has bidirectional energy transmission function has been widely used in DC uninterruptible power systems, distributed generation system and multi port hybrid power supply system and so on. However, the bi-directional DC/DC converter which could meet high voltage and high power requirements are not many at present. In this paper, aiming at the difficulties in the field of the DC/DC converter, bi directional DC/DC converter which is suitable for high voltage and high power applications has been studied.Based on the deep understanding of the bi-directional DC/DC converter research status at home and abroad and the basic topological structure, A topological structure for variable switching capability of bidirectional DC/DC converter which can be better used in high voltage and high power application is proposed. The topological structure can solve the problems of high frequency large capacity transformer magnetic saturation and low side rectifier diode voltage oscillation. Then, the work principle and soft switching technology for the bidirectional DC/DC converter of with DC blocking capacitor and active clamp circuit dual full bridge are analyzed in the paper. And the lagging leg ZVS turn-off is discussed in detail as well. Finally, a 10 kW bi-directional DC/DC converter system is designed in detail, containing the main components of the calculation and selection, energy storage device design and charge control, the main control circuit. In order to solve the design problem of high frequency isolation transformer, the nanocrystalline magnetic core and "sandwich" winding are employed. By the methods, the heat loss of the high frequency islolation transformer and the weight are effectively reduced.The validity of the theoretical analysis and the rationality of the device selection are proved by the experiment. This converter not only has the advantages of the traditional full bridge bidirectional DC/DC converter, but also can improve the system efficiency and reduce the volume, can be better applied in the high voltage and high power applications.