With the development of global industry, the massive increase in carbon dioxide emissions during the industrialization process has led to climate deterioration. The successful application of dimming technology in LED lighting will further improve the effect of energy saving and emission reduction.
The application of dimming technology will further reduce energy consumption and save electricity for lighting. At present, public lighting electricity accounts for one-third of the entire lighting field, up to 100 billion degrees. The city usually lights up from 5:30 or 6:00 in the evening. However, after 9:00 in the small city and after 12 o'clock in the middle and large cities in the small city, there are few passersby on the road. From this period of time to 6 o'clock in the morning, the street lights are extinguished, and it is obviously not necessary to maintain a high illumination on the road with low traffic flow. If the dimming technology can be adopted, the output power of the LED street lamp will be reduced to half after the 12:00 midnight with the decrease of the traffic flow, and the power consumption will be as high as 50 billion degrees, and the energy saving effect is very remarkable.
The use of dimming technology to reduce the output power will significantly improve the working environment of LED lamps, extend the life of lamps and improve reliability. The key factor affecting the reliability of LED luminaires is temperature. Whether it is an LED driver or an LED chip, the higher the ambient temperature, the sharper its life and reliability.
The higher the temperature, the more pronounced the light decay of the LED chip. The earlier the LED light source appears, the shorter the lifetime. The key to extending the life of an LED source is to reduce the junction temperature.
With dimming technology, as the output power is reduced, the loss of the drive power supply will also decrease, and the case temperature will also decrease. When the ambient temperature is 25 ° C full load output, the case temperature is 50 ° C, and when the dimming technology is used to control the output only 50% power, the case temperature drops to 40 ° C, the life will also double, the reliability can be increased by 25% - 40%.
The current mainstream dimming method is pulse modulation (PWM). In this way, the driving current is square wave-shaped by a certain control, and the pulse width is variable. The pulse width is adjusted to change the time during which the LED lamp is continuously lit, and the output power is also changed, thereby achieving the purpose of energy saving. The frequency is generally controlled at 200 Hz to 10 kHz. Due to the retention of human eye vision, the flicker of the light source during the dimming process is not felt. The advantage of this dimming method is that it can improve the heat dissipation of the LED. The disadvantage is that the overshoot of the driving current has a certain influence on the life of the LED chip.
The dimming methods are all classified according to the control of the LED drive current output. The control circuit can also be divided into analog control and PWM control, and the control circuit is usually realized by a microcontroller.