Of Nizn Core Material High-frequency Dc-dc Converter

With the development of electronic and IT technologies, the power supply system of all kinds of electronic equipments are required to be smaller and more reliable. The key to that goal is the technique of high frequency switching power supply. The basic technique to achieve the target is that raising the frequency of the power supply, mainly of DC-DC converter.There are several key techniques by which we carry out the high frequency of the DC-DC converter. They are high frequency and low loss ferrite technique, design-optimization of the high frequency transformer and circuit technique, and install of DC-DC converter technique.MnZn ferrite is widely used as core material of power supplies or DC-DC converters. But MnZn ferrite has very low resistance (100Ωcm), which results in high current loss of transformer.The work frequency of this kind of transformer is not beyond 2MHz. Recently, a new scientific idea that NiZn takes place of MnZn is born.It is helpful for increasing the work frequency of DC-DC converter.Therefore, the relative researches are becoming the hotspot and bottleneck.The statement above are the background and objective of the paper.1.NiZn ferrite was developed for using in mini high frequency DC-DC converters and inductors. We measured and analysed the parameters of the NiZn ferrite, which we concern about when designing the DC-DC converter.2.The low loss sample of NiZn ferrite were chosen for design-optimization of the high frequency transformer.Based on the relevant theoretical researches,the loss Properties of the magnetic core material and winding were analyzed in this thesis. We took the high frequency flyback converter design as an example and made a calculation model of the total loss of the high frequency flyback transformer. On basis of the caculation model combined with the systemic method of designing DC-DC converter, and the method which is base on the current shape, is presented to achieve the appropriate parameters of the flyback transformer, an optimized approach to design high frequency DC-DC converter is given in this paper. The appropriate parameters were achieved by genetic algorithm.Through this method, a practical high frequency flyback...