Design Of Solar Lighting System Controller And Test Of Health State Of Battery

With the intense situation of global energy supply, solar photovoltaic power generation achieves more and more attentions. With the emergence of new energy-saving lamps, solar lighting systems have been widely used in the fields of solar street lamps, garden lights and other fields in our daily life.Solar lighting systems have some advantages such as pollution-free, outdoor maintenance free, long service life, used in off-grid lighting status, long running time with low cost, and so on. As countries increase investment in the field, solar lighting system has been widely used in street lighting and other lighting fields.Lead-acid batteries are widely used as the power of energy and many other important areas of energy storage devices, solar lighting systems are energy reserves devices because of its excellent economic characteristics and stability. Existing solar lighting systems usually replace lead-acid battery with fixed period, lacking methods to test lead-acid battery health, unable to grasp the usage situation of batteries, and this method usually lead to waste and excessive use of battery.The main contents include the following aspects:1) Analyse the related characteristics of solar lighting system, research the principle of photovoltaic solar cells, the influence of light intensity and temperature on characteristics, test and find the main factors affecting the system. Estimate light intensity through detecting the parameters of solar panels; Research principles of chemical reaction of lead-acid battery, charge and discharge characteristics, complete charge mode discrimination and low voltage protection function, prevent excessive charge and over-discharge; Research LED light source and the general DC light source, select appropriate source combined with battery performance and control effects.2) Design charging method focused on charging efficiency in large power systems, using maximum power tracking method to ensure maximum output of solar cell and improve system efficiency; Control with PWM signal in the late period of charging, reduce the accumulation of gases in the battery, reduce the pressure to protect battery; charge with small current in the end of charging period, maintain battery voltage and ensure the maximum capacity without damaging battery.3) Analyse the principle of maximum power point tracking combining with Buck-Boost DC/DC conversion circuit. Obtain the equivalent circuit model. Establish a mathematical model of maximum power tracking. Find the control variables of solar cell output power to change the output power. Design different control strategies for different needs of system.4) Complete system hardware design and test function of system. Design common anode connection of Solar cells and lead-acid batteries, using PIC microcontrollers as main control chip, charge and discharge circuit, voltage and current detection circuit and auxiliary circuit. Design charging algorithms and control strategy, design overall framework of system software, the control algorithms of charging waveform, software functions to remove interference and select settings. verify the effectiveness and stability of circuit and system function.5) Research loss of lead-acid batteries in the process of using. Find out variables and aging factors associated with battery, design a real-time detection method for battery state of health combining with the system circuit, replace lead-acid battery according to testing result.