The Design Of200W Portable Off-grid Solar PV Inverter

With the exhausted of traditional energy sources, the worsening of the ecologicalenvironment and human requirements of sustainable development, solar energy as anideal green energy has caused more and more attention, to become the world’s mostpromising new energy technology. In order to solve the electricity needs of remoteareas, off-grid photovoltaic power generation system has been widely used. In thispaper, off-grid inverter is the object of our study, which is the core equipment ofphotovoltaic off-grid power generation system. We design a portable off-grid PVinverter which is based on low-cost digital the processor TMS320F28020anddedicated PWM chip TL494, it can meet the needs of low-power applications.Firstly, in order to maximize the use of solar energy, improve system efficiency,this paper studies the solar panel maximum power point tracking (MPPT) algorithm.In the MATLAB environment, we use of Simulink tools to build a model, Simulationof the adaptive perturbation and observation method, which verifies the correctness oftheir theoretical analysis. At the same time, we have established a system model of theinverter, and carried out a simulation. The simulation results can verify whether theymeet the design requirements.Secondly, the paper introduces the hardware design plan based on digital signalprocessor TMS320F28020,which mainly includes the inverter circuit, control circuitand auxiliary circuit, sampling circuit, drive circuit and protection circuit. The maincircuit of this article uses a relatively simple isolated two conversion topology that is“push-pull circuit+single-phase full-bridge inverter” design plan. The control circuitadopts a dual microcontroller control scheme and uses a three-stage charging strategyto charge the battery.Finally, the software part using C language to give the system with a modularprogram design plan in DSP development environment CCS3.3, that contains the mainprogram module, the interrupt subroutine modules, AD sampling module, batterycharging module with MPPT, PWM flow chart of the subroutine modules.Simultaneously, the paper verify the whole system by experiments, design a200Wprototype. Experimental results show that the system meets the design requirements,and feasibility of control methods and strategies.