Research On Constant-Current Driving Technology Of High Power LED Use For Lighting

In modern society, the energy problem increasingly concerned, efficient use of electricity is an important aspect of energy-saving, and the lighting electricity consumption in the world play an inportant proportion. With the development of semiconductor lighting technology, high power LED has the features of energy efficient, environmentally friendly, high reliability, long life etc, it becomes a new type of light source which consistent with the comcept of green lighting, and gets more and more widely used.LED electrical characteristics are discrete, and the sensitivity of current higher than the voltage in optical properties. Thus, the high-quality LED driver offen used constant current control mode. The constant current dirver of based on switching regulator which has advantages of high efficiency, wide input range, and adjust current simply, it becomes popular. The constant current dirver of based on switching regulator which mainly by power supply and constant current control unit constitute.According to IEC61000-3-2 standard of lighting equipment requirements, the constant current driver contains PFC circuit. In this paper, design two kands of PFC circuit. One type is the Boost APFC, the other one is interleaved PFC which is based on the Boost circuit. Both of them have improved power factor of the system, and reduced input current harmonics.PFC output voltage is a stable 400V DC, this voltage is higher than the input voltage of constant current unit, so we need to buck transformation. There are two main problems in taditional Buck DC/DC converter, one is the contradiction between the input voltage range and efficiency; the other one is the problem of rectifier diode reverse recovery in transformer secondary side. Here proposed a new type of resonant converter, we called half-bridge LLC resonant converter. This type of resonant converter can solve these issues. The converter primary side swiches work in the ZVS conditions, the secondary rectifier diodes work in the ZCS conditions. In the case of wide-range input, the high efficiency we can get in the high-end of input voltage.In this paper, LED array structure used in muti-branch parallel single branch in series form. Constant current control unit is a Boost circuit that based on the peak current control, the aim is to connect more LED in each branch.At last, design two drivers and studyed by the experiment, obtained the two prototype both achieved the system requments.