Research And Design Of Solar Charging System Based On FPGA

After entering the21st century, how to develop the economy sustainable under thedouble restrictions of the limited energy and environmental protection, has became aenormous historical topic human faced with. The deficient of conventional energy and thedestruction of the environment from fossil energy are forcing people to develop and use greennew energy on a large scale. Among the numerous new energy, solar has been developedvigorously by human for its abundant reserves, wide distribution, clean, economy, highavailability, etc[1].Charging technology combined with photovoltaic technology is in a rapidly developingstage, and has made great progress already. But charging efficiency of charger is still notideal, how to improve utilization of solar cells by using MPPT technology reasonable is stilla technical problem in this area.Switching power supply becomes the direction of development of future power supplyfor its small size, light weight, high efficiency, low calorific, stable performance. At thetime of choosing the structure of the charging circuit, noticed that the requirements of therelationship between input voltage and output voltage of BUCK converter and BOOSTconverter, limit their application. In order to make the system meets the requirements ofphotovoltaic charging application, taking system costs account as well, instead of choosingthe BUCK converter and BOOST converter segmented running-parallel circuit structure,select the BUCK-BOOST converter and a new MPPT technology---WVSVH P&O method toachieve the goal of charging energy storage devices efficiently by tracking the maximumpower point of solar cells quickly and accurately[2]~[3].This article introduces an efficient solar charging system based on FPGA. The chargingcircuit composed of BUCK-BOOST switch converter, realizes the function of maximumpower point tracking(MPPT) of solar cells by using high speed controller---FPGA and a newMPPT technology---Weighted Variable-Step Voltage-Hysteresis Perturbation&Observation(WVSVH P&O) method. This paper explains the design by its circuit configuration and control system, and simulates it in the simulink. The simulation results show that, thistopology is able to achieve the purpose of charging efficiently with solar cells; The controlstrategy used here, compared with the conventional MPPT methods, shows its superiority offast and efficient.The experimental result shows that theoretical analysis of the solar charging system iscorrect, the control strategy is feasible and the performance meet the design requirements.