International OPEN ACCESS Journal Of Modern Engineering Research (IJMER) | IJMER | ISSN: 2249–6645 | www.ijmer.com | Vol. 4 | Iss. 3 | Mar. 2014 | 38 | Simulation of a Two Stage High Power Factor Driver for White Power Led Ambily Krishnadas 1 , Rabiya Rasheed 2 1 (Student, Department of Electrical and Electronics Engineering, FISAT, MG university, Kerala, India) 2 (Assistant Professor, Department of Electrical and Electronics Engineering, FISAT, MG university, Kerala, India) I. INTRODUCTION Energy prices have skyrocketed in recent years owing to depleting renewable resources. In addition to seeking other energy sources, countries worldwide are also initiating energy-saving and carbon reduction programs. Due to the small size and high efficiency, semiconductor lighting has attracted researchers and manufacturers to develop new products using this technology. Nowadays the energy-inefficient incandescent lamps and mercury-based tubular and compact fluorescent lamps are replacing LED lamps. Although HB white LEDs are not the most efficient lighting systems in terms of lumens per watt for streetlight applications (indeed, they achieve a lower efficiency than low-pressure sodium vapor lamps), they are quite interesting compared to traditional solutions due to their longer operating life and their more pleasant light spectrum (sodium lights emit only in yellow color, thus providing a very poor Color Rendering Index, CRI). High Brightness-LEDs do not need neither warm up nor restart period, which do imply the use of specific circuitry. Due to the high efficiency of the LEDs with maximum illumination, the utilization is 85%-90% of the input power into light energy, whereas the fluorescent lamps will produce only 77%. On the other hand global warming and increasing power demand etc. may be fulfilled by LEDs by implementing enhanced control technique (light dimming and preheating of filaments if possible). The recombination of electrons and holes can cause either photons (light) or phonons (heat). So the junction temperature of the LEDs increasing leads to the degradation of the luminous flux of LEDs [11]. The high efficacy of power LEDs is only maintained under strict operating conditions, which include low direct current and low junction temperature (Fig 1). All these mean that the development of power supplies that achieve correct driving of the LED-based lamp is an important topic of research [16]–[20]. White power LEDs are becoming an attractive light source, owing to their high reliability, long life, high color rendering index, and small size [1]. In addition, there are commercially available units that can reach light efficacies as high as 100 lm/W. All these features make white LEDs a good candidate to override fluorescent and other discharge lamps. The main drawback of these LEDs is they need constant voltage as input and they need current limiter before the input of the LED. Therefore, some kind of current-limiting device must be used, similarly to the ballast used to limit the current through a discharge lamp. On the other hand, the high efficacy of power LEDs is only maintained under strict operating conditions, which include low direct current and low junction temperature. A review of literature shows that a variety of LED power supplies and driver solutions, which can accurately control the current of the LED while achieving a near-unity input power factor, have been proposed ABSTRACT : In this paper, an integrated double buck–boost (IDBB) converter is proposed as a high- power-factor offline power supply for power-LED lamps. The IDBB converter features just one controlled switch and two inductors and is able to supply a solid-state lamp from the mains, providing high power factor and good efficiency. In this paper, the IDBB converter is analyzed, and a design methodology is proposed. It is demonstrated that, with a careful design of the converter, the filter capacitances can be made small enough so that film capacitors may be used. In this way, the converter mean time between failures can be made as high as that of the solid-state lamp. A design example for a 70-W converter supplied from a 230 V/50 Hz mains for street lighting applications is shown. MATLAB is applied to execute the whole circuit simulations. Finally, simulation results demonstrate that the power factor of the closed-loop IDBB converter is 0.993 and the output voltage of the designed controller can be stably maintained at 200V. Keywords : Continuous Conduction Mode (CCM), Discontinuous Conduction Mode (DCM), Duty cycle (D), Integrated double Buck–boost (IDBB), white power LED