Analysis Of LED Driver In Automobile Lighting System

Nowadays, the application of Light-Emitting Diode (LED) is widely. LED lamps have lots of advantages comparing with traditional lamps. Along with the increase of LED's power, high light LED lamps have a great potential to replace traditional light source. In the area of automobile light source, LED lamps are also used widely as back light lamps, pilot lamps, reading lamps, color lamps etc. inside cars and high side stop lamps. Although it is a low power grade application, but in the near future, we believe that LED lamps will be used as sidelights, taillights, daytime running lamps so much as headlights with improved product technique of LED. The research of high power LED driver circuit comes avid and challengeable. The most powerful and efficient direct current LED driver circuit is the inductor switch converter recently. At a early time these DC-DC converters were used as voltage regulators normally, but now, LED's special photoelectric characteristic requires a constant current source with high stability as its driver. So we need to modulate and optimize varied DC-DC converters firstly.This paper aims at the surroundings of automobile light system, divided into three parts, designs and analyses drivers with different voltage structures. In the Buck converter system, the simplest and fastest control method constant on-time (COT) control mode is chosen to obtain good steady precision and dynamic performance because that the output current is controlled by inductor current directly. In the Boost converter system, a Tristate switch technique is used to eliminate the right half plane (RHP) zero's disadvantage influence. Cooperating with constant on-time one-cycle control mode, switch exchange control mode and inductor current regulator, this system obtains accurate average output current and fast dynamic performance and a large stability margin. In the Boost-buck converter system, a advanced Zeta converter topology is provided to get high dynamic performance as Buck's with constant on-time control strategy and definite components matching rules. On the side, based on the advanced Zeta converter a Tristate switch circuit is added, which could make the system obtain better stability and reduce the dependence of components' parameters. Farther more, this paper provides series of Boost-buck converter topologies, analyses steady performance and makes a simple introduce. These novel converters can also use the control strategy supplied in the paper. All of the departments are emulated by PSIM and some of them are proved by the experiment circuits.