Research On Double-input Current Source SEPIC Converter

With the increasing depletion of traditional energy and worse environment pollution, the dominant methodology of distributed generation switches to the use of the new energy which becomes more promising and more attractive. Meanwhile, scholars at home and abroad have initiated extensive research on the terminal DC load oriented distributed power supply. The basic role of power supply is to provide stable electrical power, but it is hard to be implemented in a power supply system with the new energy such as solar energy, wind energy, etc. It is widely accepted that those energies are unstable and easy to be influenced by the environment factors. Since of that, the promising direction is to union two or more different new energy at the same time for power supply. In order to optimize the topology of the converter and to save expense simultaneously, people are more focusing on the multi-input converter in electricity generation. According to the references, the pattern of the output current coming from the photovoltaic cells and fuel cells will result in several issues such as lower efficiency and shortening service life, etc. Therefore, the multi-input current sources converter becomes the dominant researching direction. This thesis investigates the design of multi-input current sources converter for the medium and small power applications.Due to the special input inductors topology, the dual current source input SEPIC converter is good at restraining output current ripple and is suitable in the medium and small power applications. Based on a thorough research on the principle and control strategy of the converter, this thesis firstly applies a passive absorption method which overcomes the leakage inductor in the converter because of the transformer, then analyzes of the unsuitability of RCD clamp circuit, and finally proposes the design method of RCD buffer circuit. This method uses the active clamp technique to absorb and make full use of the leakage inductor's energy from the transformer in realizing the clamp switch works in the zero voltage switching. Moreover, this thesis optimizes the active clamp dual input SEPIC circuit and proposes a better methodology of applying the coupled inductance technology to restrain the input current pattern and synchronous rectification technology to reduce the loss of output side rectifier circuit in order to realize the zero voltage switching of synchronous rectifier tube.Finally, the theoretical analysis results are verified by the simulations in Saber and experiments in a 200 W experimental prototype.