Design and Application of All-in-One Solar Street Light with MPPT Charge Controller

Application Points of All-in-One Solar Street Light Illumination

In the process of designing the charging and discharging functions of integrated street lamps, the following two aspects should be paid great attention to. On the one hand, the hardware design scheme, the main circuit of the system can be divided into two parts, one of which is the charging circuit, the role is to use the solar panel to charge the battery; the other part is the discharge circuit, the role is to use the battery's electrical energy to supply power to the constant-current source LED. When charging, it can be controlled by MPPT algorithm for maximum power tracking to maximize the absorption of power from the solar panel. When charging the battery through the DC/DC circuit, the charging circuit is unidirectional and single circuit, which only allows the solar panel to charge the battery, thus preventing the effect of backlash. When the battery voltage is higher than the photovoltaic panel voltage, it is controlled to prevent reverse charging from occurring. The input voltage of the linear power supply chip should be the higher side of the solar panel or battery voltage. On the other hand, it is to determine the software design program, for photovoltaic conversion, the core control method is the MPPT algorithm, in the light, temperature constantly changing conditions, the controller can make the photovoltaic array operate under the maximum power point, which is conducive to promote the solar energy conversion of electrical energy efficiency. The design process can use the disturbance observation method, where the disturbance variable is artificially added to the PV system to observe the effect it has, and then the output power before and after the disturbance is compared. If the output power is lower than before the disturbance, it indicates that the operating point has deviated and the controller will calibrate it.

When carrying out the design of integrated solar street lights, on occasions where sensors can be used, they can be combined with sensors to save energy effectively, thus reducing the specifications of solar panels and batteries and realizing better economy. At the same time, it is also necessary to absorb more solar energy by adjusting the light angle, so that the solar panel can achieve the highest efficiency of photovoltaic conversion, in line with the requirements of road lighting for roads with different orientations.

Reasonable selection of battery models to extend battery life

Battery selection and life have an important impact on the quality of all-in-one solar street lights, should be based on the road lighting needs to choose the right battery model, extend battery life.

When designing solar street lights, the charging design and adaptive discharge design should be optimized. The charging design uses PWM pulse width modulation to control and regulate accordingly to the size of the battery voltage. When the battery is in an undervoltage state, constant current charging can be used, and when the voltage exceeds 12V, direct charging is used. When designing adaptive discharge, it is necessary to judge the battery power at night and then calculate the brightness adjustment parameters. The battery power has three critical points, respectively 80%, 60% and 30%, the brightness of different critical points is different, which requires effective dimming to reduce power.