The topologies of white LED lamps´ power drivers

This paper demonstrates power electronic drivers for white LED lamps. Due to some obvious features such as high luminous efficiency, low-loss energy, long life, safety, green, and so on, it´s expected to replace conventional lamps including incandescent, halogen and fluorescent lamps at least in some general illumination application within the near future. It´s always used in automotive fields. Innovative design in driver circuits of white LED lamps with respect of functionality, efficiency, cost, size and reliability enables the successful introduction of new LED based lighting products. First of all, it describes LED´s characteristics briefly which include electrical character, driver requirement, luminous characteristic, thermal performance and package structure. In the second part, a series connection of single LED cells is presented in detail. For efficiency reasons, white LED lamps can not be droved via series resistor, but need PWM models with current control. In the third part, different standard DC-DC converter topologies are discussed which can be adapted to feed a constant current into a LED load. Hence, roughly, it consists of two general types which named non-isolated driver and isolated driver separately. This paper will introduce more detailed classifications. It´s convenient to choose proper driver circuit and suited components through the comparison between the topologies of this paper. In addition, PFC (power factor correction) circuit is also involved in high power factor. Finally, some hot spots in white LED lamps fields are focused on.