Research On Power Conversion System Of Independent Tidal Energy Generation

With the rapid development of society, the storage of traditional fossil energy sources reduced gradually. While large-scale use of fossil fuels caused great harm on the environment.Therefore, New Energy electricity generation has got high attention, especially wind power generation, photovoltaic generation and tidal generation electricity. China has rich tidal current energy resources, but low utilization, because researches on tidal generation electricity were just started. Therefore, tidal power technology research has more promising.In this thesis, independent tidal generation power conversion system was studied, and structure of tidal generation power conversion system was proposed. This thesis focused on phase-shifted full-bridge converter and three-phase inverter, a detailed analyzing the working process of phase-shifted full-bridge converter. In order to achieve soft switch of the phase-shifted full-bridge converter switches, resonant inductor, resonant capacitor, dead time setting and the way of the ratio of high-frequency transformer calculation were given and the DC filter circuit was designed. Apart from this, the thesis analyzed the working principle of applicating split capacitor type three-phase inverter and designed the AC filter circuit for independent tidal current energy generation power conversion system with unbalanced load.The thesis established small-signal model of phase-shifted full-bridge converter and three-phase inverter by using state-space averaging method, which has no coupling relationship among the three phases. Single-phase dq coordinate transformation and Engineering Design was used for proposing the equalizing control strategy of Internal bus voltage divider capacitor. Finally, controller parameters were verified by simulation software.In this thesis, hardware control circuit based on STM32F407IG was designed and the flow chart of section software design of the system was given. Simulation and experimental results with load change suddenly and imbalance load indicate that the circuit design parameters were reasonable and the control algorithm is effective.