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Nowadays, power LEDs are widely used in the lighting sector due to their extensive lifetime, durability and high efficiency compared to the traditional lighting sources. As power LEDs draw high currents, they need special driver circuits. These circuits include AC-DC converters drawing harmonic current from the grid and decreasing the power factor. These converters can be replaced by AC-DC converters with active PFC. Therefore, the power factor is approximated to unity and power quality can be improved by drawing sinusoidal currents with reduced harmonic content. In this study, two flyback type circuits with internal and external PFC, which correct the input power factor and drive the power LEDs after reducing the harmonic content of the current drawn from grid, were designed and implemented. As a result of the experiments involving 20 W power LED, for power LED driver with external PFC, power factor and THD values were found as 0.93 and 31.1%, respectively. For the circuit with internal PFC, these values were 0.97 and 10.4%, respectively. The drivers implemented in this study satisfy the requirements of EN 61000- 3-2 C class harmonic standard. The circuits were simulated by PSpice and it was observed that the simulation and experimental results are coherent with each other.

Design, Implementation and Comparison of Flyback Type Power LED Drivers with External and Internal PFC in Terms of Harmonics and Power Factor