Research And Design Of The Stand-alone Photovoltaic System Based On ARM

Photovoltaic cells, as input source of the stand-alone PV system, need an engineering model thatsatisfies certain accuracy. Its working principle and the equivalent circuit were analyzed in order toapply a simulation tool to verify and improve the algorithm. Lead-acid storage battery was chosen asenergy storage module in a stand-alone PV system after the comparative study of several batteries.Combined with the technology of maximum power point tracking(MPPT), a three-stage chargingmethod was adopted. In first stage, maximum power point tracking was applied to replace theconstant current charging, and with the simulation software to verify the charging process. Simulationtest with that model was carried out under different external environment. Relation curve obtainedbetween voltage, current and power meets the actual situation, which helps to research maximumpower point tracking algorithm.At present, as a part of the photovoltaic system, the technology of maximum power pointtracking related to the design and application has been widely studied. In this article, throughcomparative study of the popular disturbance and observation method and incremental conductancemethod, their respective tracking principle and difference were analyzed. Their shortage was pointedout with the simulation tool for validation. The improved fuzzy control algorithm was proposed onthat basis, with the change of the power and duty ratio change rate as the input, the duty ratio as theoutput. In the design of the fuzzy rule, weighting factor was established which made the changes ofthe controlled variable more gently close to the maximum power point, decreasing the oscillation ofthe stable point. Buck circuit for impedance transformation and the ideal waveform were analyzed indetail and the selection of component parameters was given out.Finally, this paper put forward a complete system design, including the choice of main chargercircuit, device in a DC/DC converter, the design of drive circuit, sample circuit, etc. The controllerbased on ARM framework with low power consumption was chosen to carry out the batterymanagement. The system expands the wireless charging module and wireless communication module.A hardware platform was established on that basis to detect the waveform and verify the function andprinciple of the system.