| Stand-alone Photovoltaic Power System has become the main way to solve theenergy crisis and improve the environment. However, there are several shortcomings, suchas low conversion efficiency, short lifetime of storage batteries and low system stability.These disadvantages make cost even higher than traditional power generation, and lostmarket competitiveness. The main subject of the research is to improve the efficiency ofthe photovoltaic power generation system and prolong the service life of batteries inphotovoltaic power generation system, which is conducive to the promotion andapplication of photovoltaic power generation. The main content of this paper is as follows.Firstly, the main components characteristics of the independent photovoltaic powergeneration system was analyzed. The simulation mode of photovoltaic cells wasestablished by use Matlab/Simulink. This part mainly expounds the factors that affect theoutput characteristics of photovoltaic cells. The battery charge and dischargecharacteristics of the photovoltaic power generation system, and the main reason affectingits life was analyzed and summarized. Based on the analysis of common control circuit, acontrol scheme is proposed that will help improve the efficiency and increase of batterylife.Secondly, according to the analysis of a variety of charging methods for photovoltaicpower generation system and topology of DC-DC Circuit, the control circuit of two-phaseparallel and phase staggered was designed by use a switching power supply chip LTC3787.The charging voltage can be adjusted by the photovoltaic cell output voltage range, that issatisfy of24V and48V battery charging. Numerical simulation were performed tocompares the voltage stability of charged circuit in single-phase work and paralleloperation charge using LTspice software, and then the conversion efficiency of circuit wascompared that use synchronous rectifier design and fly-wheel diode design.Thirdly, a new equalization scheme is proposed according to the analysis of batterybalance discriminant basis and on the basis of existing equalization circuit. With voltagevalue for balance discriminate basis, an equalization circuit that don’t need detection and can be modular application was designed. This equalization circuit can reach the voltagebalanced of automatically and synchronous when charging. Then the feasibility of thecircuit in the equalization process and energy transfer theory was analyzed.Finally, the experiment showed that the scheme designed in this paper can achieveefficient energy storage of photovoltaic power battery, and it can protect the battery andprolong its life better. |
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