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Research On Soft Switching BUCK Converter With Conpled Inductor

Posted on:2017-08-08Degree:MasterType:Thesis
Country:ChinaCandidate:X X WeiFull Text:PDF
GTID:2322330503966125Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
Buck converters are widely used, which can provide DC power supply to the voice coil motor, DC motor and electronic equipments, etc. The more efficient and smaller size of buck DC power supply is always a hotspot to research. Therefore, the study of the buck converter, to improve the reliability and efficiency of the power supply, and to reduce its size and weight by optimizing the design, has an important application value and practical significance.Based on the investigation of a large number of soft switching converter topologies, a soft switching buck converter with coupled inductor is proposed by improving and optimizing, and using the method that the filter inductor is replaced by coupled inductor. Detailed theoretical analysis and formula derivation of each mode of the improved buck converter is presented, and then the ideal waveforms of the main components' voltage and current in one cycle are given. Forthermore, the control methods of the switch and freewheeling diode to achieve soft switching are discussed respectively. Besides, the mathematical model of the coupled inductor is analyzed, as well as the core material and core shape are discussed and optimized. The effect of the switching components' voltage and current stress of the improved buck converter and its performance with the coupled inductor's turn ratio changing are analysed in detail. According to the needs, the different turn ratios of the coupled inductors are manufactured. Then the inductance of the coupled inductor is measured directly, and the mutual inductance is measured using an equivalent circuit.To make each switching components of the improved buck converter in the condition of the soft switching, it is necessary to choose an appropriate parameter value for the coupled inductor and resonant capacitor. The select of the coupled inductor and the resonant capacitor are discussed in this paper, and then the parameter value of the improved buck converter, such as input and output voltage, switching cycle and other parameters, are given. The simulation model of the improved buck converter is carried out to study in detail. The simulation waveforms show that the switching components of the improved buck converter all can achieve the soft switching under the different turn ratio of the coupled inductor. In addition, the voltage and current stress of the switching components and coupled inductor are all not large. The switching components' power losses of the improved buck converter are also simulated, and the simulation results show that the power losses of the switching components are inversely proportional to the number of the coupled inductor's turn ratio.A 50 k Hz buck converter prototype with soft switching based on the coupled inductor of 48 V input, 32 V output is built. According to the conditions of the laboratory, an experimental hardware platform is set up. Experimental results are well consistent with that of theory and simulation, and verify the correctness of the theory and design of the improved buck converter, as well as the effectiveness of the control method. The experimental results illustrate that the improved buck converter's efficiency is increased with the increase of the coupled inductor's turn ratio under the discontinuous conduction mode.Finally, the research contents of the paper are summarized, and the existing problems and the future research directions are also pointed out.
Keywords/Search Tags:soft switching, buck converter, coupled inductor, zero voltage switching, zero current switching
PDF Full Text Request
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