Research And Design Of LED Road Lamp Driver

Energy conservation is the most significant advantage of LED (Light Emitting Diode) road lamp. In order to maximize the energy efficiency, and to meet the demand of dimming, LED drive power supply is required to shift between full load and fractional load. However, traditional high-power LED drive power supply can only gain efficiency about 85% at a full load, and even lower at a fractional load, which does not correspond with the growing requirement of LED illumination. The pollution of harmonic wave to power grid should be taken into account with large scale applications of LED road lamps, so PFC (Power Factor Correction) circuit is very necessary. The efficiency of PFC circuit declines a lot at a fractional load, which will diminish the total efficiency of power supply. Traditional PFC circuit performs badly in heat dissipation because it uses high-value inductor to boost the voltage, and high temperature will have a negative impact on LED illumination. In this paper, a 6 driven-path LED constant current driven power supply is designed. The input voltage is single phase AC88V-264V and the output current is 6.25A.To solve these problems mentioned above, this paper designs a high-power LED constant current drive power supply by combining interlaced PFC with half-bridge LLC (Logic Link Control) resonance. First, this paper analyzes the half-bridge LLC resonance circuit to establish the fundamental approximation model, and this paper analyzes the voltage gain and impedance of the half-bridge LLC resonance circuit to design the resonance network, transformer and power devices, realize ZVS (Zero Voltage Switch) of wideband frequency switching tube and solve the problem that constant current drive power supply gains low efficiency at a light load. Second, with the combined advantages of DCM and CCM, this interlaced PFC circuit based on NCP1631 reduces RMS of output current and improves the efficiency. Third, the performance of heat dissipation gets better by replacing high-value inductor with two low-power inductors. The effect of environment temperature on LED is diminished. Finally, the constant current buck circuit is designed based on the LM3404, which reduce the LED light decline and increase using life of LED.The experimental results show that the power achieved the desired goal, and its operations were stable. When the load of LED light changed, the power could meet requirements of the high efficiency and high power factor.