Single-Stage Power-Factor-Correction Circuit with Flyback
Converter to Drive LEDs for Lighting Applications
ABSTRACT:
White light emitting diode (LED) with high brightness
has attracted a lot of attention from both industry and academia for its high
efficiency, ease to drive, environmental friendliness, and long lifespan. They
become possible applications to replace the incandescent bulbs and fluorescent
lamps in residential, industrial and commercial lighting. The realization of
this new lighting source requires both tight LED voltage regulation and high
power factor as well. This paper proposed a single-stage flyback converter for the
LED lighting applications and input power factor correction. A type-II
compensator has been inserted in the voltage loop providing sufficient
bandwidth and stable phase margin. The flyback converter is controlled with
voltage mode pulse width modulation (PWM) and run in discontinuous conduction
mode (DCM) so that the inductor current follows the rectified input voltage,
resulting in high power factor. A prototype topology of closed-loop, single stage
flyback converter for LED driver circuit designed for an 18W LED lighting
source is constructed and tested to verify the theoretical predictions. The
measured performance of the LED lighting fixture can achieve a high power
factor greater than 0.998 and a low total harmonic distortion less than 5.0%. Experimental
results show the functionality of the overall system and prove it to be an
effective solution for the new lighting applications.
KEYWORDS:
1. Light emitting diode
2. Flyback converter
3. Power factor
4. Total harmonic distortion.
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig. 1. Block diagram of closed-loop driver
circuit for LEDs lighting applications
CIRCUIT DIAGRAM:
Fig.
2. Single-stage power-factor-correction circuit with flyback converter for LEDs
driver circuit
CONCLUSION:
A single-stage power-factor-correction
circuit with flyback converter to drive LEDs for lighting applications has been
presented in this paper. The flyback converter is operated in discontinuous conduction
mode and at constant frequency providing an input power factor high enough to
satisfy present standard requirements. The operation of the proposed feedback
controller for PFC circuit has also been investigated in detail in this paper.
In comparison with the other driver topology for high-power-factor LEDs
lighting applications, the proposed topology presents a significant reduction
of cost. A prototype of the proposed PFC circuit using type-II compensator for
a LED lighting system has been successfully implemented. Experimental results
have shown that fast dynamic response, good output voltage regulation, low harmonic
distortion, and almost unity PF as well as very low THD can be achieved with
the proposed single-stage flyback converter and control scheme. The proposed
topology works as a good solution to implement low-cost, single-stage, high power-
factor driver circuit with flyback converter using type- II compensator to
drive LEDs for lighting applications.
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