Research On The Application Of Small Independent Photovoltaic Power Units

Continuous research on photovoltaic renewable energy technologies is conducive to better development of the photovoltaic power generation industry.This paper compares the domestic and foreign photovoltaic policies,and combines with the actual situation of high altitude areas in our province to design a power generating unit with a rated power of 400 W.The main work of this article is as follows:(1)The circuit adopts a double BUCK circuit topology,and the circuit model of the double BUCK and the traditional BUCK is established under MATLAB/Simulink,and the current is compared by setting the same circuit parameters.The output curve.It is proved that the output ripple of the double BUCK circuit is obviously smaller than the traditional BUCK circuit,so the topology can improve the steady-state response of the output.(2)The common algorithms of photovoltaic cells and MPPT are studied.By changing the operation mechanism of step size,MPPT algorithm with variable-step perturbation observation is proposed.It is verified through simulation that the algorithm is based on optimizing the tracking speed of fixed-step,and reduces The amplitude of oscillation at the maximum power point reduces power loss.(3)Analyze the characteristics of the lithium battery pack,design a three-stage charging method for lithium batteries,and extend the service life of the lithium battery on the basis of ensuring the safety of the entire charging process.In the inverter circuit,the 12 V voltage is boosted to 380 V using a push-pull topology.By calculating the required voltage before and after the inversion,the winding turns of the transformer is determined,and the sandwich winding method used is described.The rear inverter circuit adopts the H-bridge topology and reverses the 380 V voltage to 220V/50 Hz alternating current.(4)consider the design of the modularization,with the MSP430 and PIC16 as the control core,respectively,control the charging and inverter circuit,push-pull topology using SG3525 chip with totem circuit drive,the system peripheral circuit including voltage feedback,current feedback,drive,overvoltage Undervoltage protection.(5)Produce prototypes through hardware and software design,and test the conversion efficiency of the charging module and the output of the inverter module in a laboratory environment.Tests have shown that the power generation unit designed in this paper can achieve a conversion efficiency of up to 95.2%,and the conversion efficiency of the inverter module is up to 87.1%,while in the BUCK circuit photovoltaic controller,the charge conversion rate is up to 91.8%,verifying the high efficiency of the system..