| With large-scale new energy connected to the grid in recent years, the problem of the stability by the wind power fluctuation can not be ignored, and due to that equipping with the large-scale energy storage system is a good solution,research on energy storage system becomes a hot spot. Bi-directional DC-DC converter plays an important role in those areas, so it has attracted great attention.According to the design requirements of energy storage system, an indepth study is made on the three-level half-bridge current doubler converter. Firstly, the control method and operation principle of the converter were analyzed, the selection and design of main components were completed on the basis of circuit parameter.Then the converter is simulated by using Matlab, and the experimental prototype was builted by designing the main circuit, sampling circuit, drive circuit and control circuit of converter. Finally, the closed-loop control was realized by programmed the DSP control program. During the experiment, the reasons of voltage resonant were analyzed on the Buck and Boost directions when the swich turned off, and the resonant was eliminated through adding the clamp circuit and RCD circuit.The three-level half/full bridge converter also conducted in-depth study due to it meets design requirements of the energy storage system. First, the operation principle of traditional single-phase-shift(SPS) control was analyzed, the control method of PWM and PWM plus phase-shift were proposed aimed at large circulation power of SPS control. Then the loss models were established control mode of three-level half/full bridge converter for the three control methods, an efficiency optimization control strategy was proposed by optimization calculation for the loss models. The influence of dead time for SPS control was analyzed, and put forward the compensation method for dead time. Finally, an experimental prototype was built to verify theoretical analysis.Improvements have been made for three-level half/full bridge converter, in order to reduce output current ripple. First, the operation principle of PWM control and SPS control for the improved three-level half/full bridge converter has been analyzed, which were validated by experiments.Then the improvement of experimental prototype and the DSP control program were completed,the output current ripple has been reduced as the experimental results suggest. |
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