Dimming technology of LED lamps and its development trend

According to the control of LED driving current output terminal, it can be divided into three dimming modes. The control circuit can also be divided into analog control and PWM control. The control circuit is usually realized by microcontroller. First, the main dimming technology of LED lamps is to adjust the LED driving current to realize the dimming of LED lamps, because the brightness of LED chips is proportional to the LED driving current. The second dimming method is commonly referred to as analog dimming or linear dimming. The advantages of this dimming method are that when the driving current increases or decreases linearly, the influence of driving current overshoot on LED chips is relatively reduced, and the anti-interference performance of the control circuit is stronger. The disadvantage is that the change of driving current will have certain influence on the color temperature of LED chip. The third dimming method is pulse brightness modulation (PWM)Way. In this way, the driving current is wavy in a square shape through certain control, and the pulse width is variable. The time of continuous lighting of the LED lamp is changed through the adjustment of the pulse width, and the output power is also changed, so as to achieve the purpose of energy conservation. The frequency is generally controlled at 200Hz ~ 10 KHz, due to the retention of human eye vision, the flicker of the light source during dimming will not be felt. The advantage of this dimming method is that it can improve the heat dissipation of the LED, and the disadvantage is that the overshoot of the driving current has a certain influence on the life of the LED chip. Second, the composition of the dimming system and the future development of perfect intelligent control should have manual control, intelligent control, light control, time control and fault alarm control functions. When the sun goes down and the sky fades, it will light up automatically, and the illuminance of the light will be halved automatically after midnight; After dawn, the light can be automatically extinguished; Under special circumstances, people can control it manually; When the lamp fails, the control system can automatically alarm. The intelligent dimming system is mainly composed of four parts: Server, central controller, single chip controller and signal detection circuit. Server: It is composed of upper computer and upper computer software, and mainly realizes monitoring operation and alarm functions. The server is located in a control center such as street lamp management, and its connection with the central controller can be power carrier, network or wireless.