Research And Design Of An Efficient And Intelligent Led Street Lamp Drive Power

LED lamps have the great advantage of efficiency, green, long lifetime. Not only as a national strategy but also as a real need of everyday life, we should do our best to develop LED lamps for our better future.In the traditional switched mode power supply circuit, after the rectified bridge, a large electrolytic capacitor is connected, making the input current a sharp impulse. It contains very high harmonic component and the power factor is very low. It will also interfere the mains as a radiator. The brightness of LEDs mainly depends on the current through it. If the forward voltage of LED changes a little, it may cause a large change on its current. Thus the brightness of LEDs also will change a great deal. If LEDs are connected in multiple channels and any them is open, it may cause the current of this channel change to zero. So the current of the other channels will be larger than its normal value. This will set up a chain of reactions which finally damage all the other LEDs. Now the street lamps mainly turn on and off manually and can't adjust the brightness with different circumstances.As a study project of the Science committee of Shanghai:the demonstration application of LED lights for streets in the area of the World Expo, this paper introduce an effective and intelligent LED street lamps driver of which the power factor can reach 95% and the total efficiency can reach 85%. If the input voltage has a change of positive 10 percent or negative 15 percent, the system can still work very well. The main contribution of this work is:1. Design a new single-stage PFC-flyback switched mode power supply circuit.2. Design a fault detecting circuit and automatically adjust the output current according to it.3. Design a temperature and brightness detecting circuit and adjust the brightness of LEDs according to the brightness of the surrounding environment, the temperature of LED heatsink.4. Add a timekeeping chip, so that the lamps can turn on and off automatically according to real time.