Research And Design Of DC/DC Power Converter In Photovoltaic Power Generation System

With the gradual depletion of fossil resources, the conversion of solar energy into electricity is a common way. But during the conversion process, the low photoelectric conversion efficiency of solar cells has been a key issue in the solar applications. Therefore, the study of how to use solar power to generate energy has become the focus in the field of photovoltaic power generation. Improving the efficiency of the solar cell power output and optimizing the structure of the power conversion circuit are two research directions of the use of solar energy for power generation.This thesis proposes the interleaved technology into DC/DC power converter of photovoltaic power generation system using TMS320C28035 as a control chip and designs a full load of 500W DC/DC power converter which can carry out tracking the maximum power point. By conducting tests on solar array simulator, the results meet the design requirements. In this thesis, the completion of work is in the following areas:(1) Several commonly used MPPT control algorithms are introduced and the disturbance observation and incremental conductance method are focused on. The simulation studies point out the advantages and disadvantages of disturbance observation and incremental conductance method and the incremental conductance method is more valuable in engineering;(2) For the special requirements of power conversion circuit in photovoltaic systems, the thesis proposes to use a interleaved Boost circuit as the power conversion circuit. The thesis studies interleaved Boost circuit mode and the model of interleaved Boost circuit and provides a theoretical basis for the design of system;(3) The thesis studies the simulation of the current ripple of interleaved Boost and uses LLC resonant circuit as the high frequency isolation and uses the small signal model to propose the transfer function of interleaved Boost circuit and designs the compensation for the current loop; According to the control object features, the thesis improves dual closed-loop control strategy and designs the compensation for the voltage loop to improve the system dynamic and steady-state performance;(4) According to the requirements of the circuit parameters, the thesis designs various parts of the hardware circuit. According to the system requirements, the thesis designs various parts of the software program, including the MPPT program, interrupt service routines, background tasks state machine. The thesis debugs software with a combination of hardware circuit. The interleaved Boost converter can track the maximum power of solar panels output and provides a stable DC bus voltage.