DESIGN OF CASCADED AND PARALLEL DCDC BUCK CONVERTER FOR LED DRIVER USING MATLAB/SIMULINK

Nowadays, LED has become an emerging technology due to lifetime, luminous efficacy, power rating, and color property. So it becomes an alternative light source to replace conventional light sources in various lighting and display applications. It finds application in television, laptops, advertising displays, computer displays and optical control purposes. The developments in the LEDs have initiated the scope in designing drivers with efficient control. The dc-dc converters which are used to generate bi-level current to improve the luminous efficacy of Light Emitting Diode (LED). Amplitude mode and Pulse Width Modulation (PWM) mode are the two conventional driving techniques used in LED drivers. Amplitude mode driving technique uses constant Direct Current (DC) to drive the LED and provides a higher luminous intensity but lacks in flexibility control. Besides, PWM mode driving technique uses a pulse of dc current having higher level and zero level. It provides more flexible dimming control and color stability, but it has low luminous intensity. The bi-level current driving technique which combines the advantages of the two conventional driving techniques is discussed. A parallel and cascaded buck dc-dc converter is designed to generate the bi-level current for LED. In this paper, Resistive load is used instead of LED. The performances of the converters and tested with the simulation using MATLAB/Simulink.