Lamps can use traditional lighting fixtures. The new ultra-bright white LED lighting source has the advantages of small size, light weight, long life, energy saving and environmental protection, and is especially suitable for solar battery lighting. Ultra-high-brightness LEDs, because of the same brightness, save about 90% of power than incandescent lamps, and have been widely used, and there is a trend to gradually replace conventional lighting lamps. The luminous efficiency of ultra-high-brightness LED reaches or exceeds 100lm/W. The lifespan of LEDs is as long as 100,000 hours, while the lifespan of incandescent lamps generally does not exceed 2000h, and the lifespan of fluorescent lamps is only about 5000h. Compared with the widely used second-generation fluorescent lamps, LEDs contain no mercury and no flicker, making them an environmentally friendly light source.
As an emerging light source, LED lights are rapidly being promoted and applied in urban lighting and beautification, road lighting, courtyard lighting, indoor lighting and other lighting and applications in various fields with their unparalleled advantages. LED also has the advantages of high light quality, basically no radiation, reliability and durability, and extremely low maintenance costs. It is a typical green lighting source. The successful development of ultra-high-brightness LEDs has greatly reduced the cost of solar lamps, making them reach or close to the cost quotation for the initial installation of power frequency AC lighting systems, and have the advantages of environmental protection, easy installation, safe operation, economic and energy saving, etc. Because LEDs have the advantages of high light efficiency and low heat generation, they have been increasingly used in the field of lighting and are showing a trend to replace traditional lighting sources. Because LED lights are powered by low-voltage DC, they can be easily combined with solar batteries. In western China, non-main road solar street lights and solar garden lights have gradually become large-scale. With the vigorous development of solar lamps, “green lighting” is bound to become a trend.
LED is a DC-powered luminaire. Its working principle is: After the voltage is applied to the LED, it will generate stimulated electron transition light radiation. The light wavelengths generated by different semiconductor basic materials are different, and the light of different wavelengths is synthesized into white light. Because the light direction of the ultra-high-brightness LED light-emitting tube is too strong, the comprehensive visual effect is poor, so multiple LEDs are concentrated together, arranged and combined into a certain regular LED light source. The ultra-bright white LED luminous source must not only ensure a certain illumination intensity, but also make it have a higher luminous efficiency. Generally, the luminous flux and luminous efficiency are comprehensively considered to find an optimal working point.
The solar light is made up of multiple LED lights in series. The brightness can be adjusted by PWM, that is, by changing the current flowing through the LED, thereby adjusting the brightness of the LED lamp, the current intensity can be from a few milliamperes to 1A, and finally the LED lamp can reach the expected brightness. The PWM (Pulse Width Modulation) signal can be generated by the microcontroller or other pulse signals. The PWM signal can change the current through the LED lamp from 0 to the rated current, which can make the LED lamp change from dark to normal brightness. The smaller the PWM duty cycle (the high level time is longer), the higher the brightness. Using PWM to control the brightness of LEDs is very convenient and flexible. It is the most commonly used dimming method. The frequency of PWM can be from tens of Hz to several MHz. PWM dimming is achieved by controlling the MOSFET transistor.
