Single-Stage Flyback Power-Factor-Correction Front-End for HB LED Application


This paper presents a single-stage flyback power factor- correction (PFC) front-end for high-brightness light emitting- diode (HB LED) applications. The proposed PFC front-end circuit combines the PFC stage and the dc/dc stage into a single stage. Experimental results obtained on a 78-W (24- V/ 3.25-A) prototype circuit show that at VIN = 110 Vac, the proposed PFC front-end for HB LED applications can achieve an efficiency of 87.5%, a power factor of 0.98, and a total harmonic distortion (THD) of 14% with line-currents harmonics that meet the IEC 61000-3-2 Class C standard.


  1. Driver
  2. high-brightness light emitting diodes (HB LEDs)
  3. power factor correction (PFC)
  4. single-stage
  5. flyback



Fig. 1. Proposed PFC front-end for HB LED application


(a) LB = 83 μH

(b) LB = 166 μH

 Fig. 2. Measured line current and voltage waveforms at VIN = 110 V AC with N1 = N2 = 12 turns, (a) LB = 83 μH;

(a) LB = 83 μH

(b) LB = 166 μH

Fig. 3. Measured current and voltage waveforms, (a) LB = 83 μH; (b) LB = 166 μH. CH1: Current of primary winding N2, CH4: Current of inductor LB; CH3: Drain-to-source voltage of switch Q1. Voltage scale: 200 V/div., current scale: 2 A/div., time scale: 4

Fig. 4. Measured line voltage and current waveforms at VIN = 110 V AC with N1/N2 = 4/26, LB = 166 μH, and LM = 645 μH

Fig. 5. Measured line voltage and current waveforms at VIN = 274 V AC with N1/N2 = 4/26, LB = 415 μH, and LM = 645 μH


 A single-stage flyback power-factor-correction front-end for HB LED application is presented in this paper. With the integration of the PFC stage and dc/dc stage, significant reduction of component count, size, and cost can be achieved. Experimental results obtained on a prototype show that at VIN = 110 V AC, VO = 24 V, and IO = 3.25 A, the proposed PFC front-end for LED driver has achieved an efficiency of around 87.50%, a power factor of 0.98 and a total harmonic distortion (THD) of 14% for the line current with harmonic contents meeting IEC 61000-3-2 Class C standard. Experimental results have also been obtained at high line when the inductance of the input current shaping inductor is increased. Measured output voltage ripple with an actual LED load at VO = 24 V, IO = 3.8 A is less than 20 mV. Therefore, LED strings can be directly driven without a post regulator, improving the efficiency, lowering the cost, and reducing the size.


[1] J. Y. Tsao, “Solid-state lighting: lamps, chips, and materials for tomorrow,” IEEE Circuits and Devices Magazine, vol. 20, no. 3, pp. 28 – 37, May-June 2004.

[2] N. Narendran and Y. Gu, “Life of LED-based white light sources,” Journal of Display Technology, vol. 1, no. 1, pp. 167 – 171, Sept. 2005.

[3] T. Komine and M. Nakagawa, “Fundamental analysis for visible-light communication system using LED lights,” IEEE Transactions on Consumer Electronics, vol. 50, no. 1, pp. 100 – 107, Feb. 2004.

[4] Electromagnetic Compatibility (EMC), Part 3-2: Limits – Limits for harmonic current emissions (equipment input current ≤ 16 A per phase), International Standard IEC 61000-3-2, 2001.

[5] ON Semiconductor, “90 W, universal input, single stage, PFC converter,” AND8124-D.PDF, Dec. 2003.

A Power Quality Improved Bridgeless Converter-Based Computer Power Supply



Poor power quality, slow dynamic response, high device stress, harmonic rich, periodically dense, peaky, distorted input current are the major problems that are frequently encountered in conventional switched mode power supplies (SMPSs) used in computers. To mitigate these problems, it is proposed here to use a nonisolated bridgeless buck-boost single-ended primary inductance converter (SEPIC) in discontinuous conduction mode at the front end of an SMPS. The bridgeless SEPIC at the front end provides stiffly regulated output dc voltage even under frequent input voltage and load variations. The output of the front end converter is connected to a half-bridge dc–dc converter for isolation and also for obtaining different dc voltage levels at the load end that are needed in a personal computer. Controlling a single output voltage is able to regulate all the other dc output voltages as well. The design and simulation of the proposed power supply are carried out for obtaining an improved power quality that is verified through the experimental results.


  1. Bridgeless converter
  2. Computer power supply
  3. Input current
  4. Power factor correction (PFC)
  5. Power quality



Fig. 1. Schematic diagram of the PFC converter based SMPS.



 Fig. 2. (a) Performance of the computer power supply at rated condition. (b) Input current and its harmonic spectrum at full load condition. (c)Waveform across various components of the bridgeless converter.

Fig. 3. (a) Performance of the computer power supply at light load condition. (b) Input current and its harmonic spectrum at light load condition.


A bridgeless nonisolated SEPIC based power supply has been proposed here to mitigate the power quality problems prevalent in any conventional computer power supply. The proposed power supply is able to operate satisfactorily under wide variations in input voltages and loads. The design and simulation of the proposed power supply are initially carried to demonstrate its improved performance. Further, a laboratory prototype is built and experiments are conducted on this prototype. Test results obtained are found to be in line with the simulated performance. They corroborate the fact that the power quality problems at the front end are mitigated and hence, the proposed circuit can be a recommended solution for computers and other similar appliances.


[1] D. O. Koval and C. Carter, “Power quality characteristics of computer loads,” IEEE Trans. Ind. Appl., vol. 33, no. 3, pp. 613–621, May/Jun. 1997.

[2] A. I. Pressman,K.Billings, and T. Morey, Switching Power SupplyDesign, 3rd ed. New York, NY, USA: McGraw Hill, 2009.

[3] B. Singh, B. N. Singh, A. Chandra, K. Al-Haddad, A. Pandey, and D. P. Kothari, “A review of single-phase improved power quality AC-DC converters,” IEEE Trans. Ind. Electron., vol. 50, no. 5, pp. 962–981, Oct. 2003.

[4] K. Mino, H. Matsumoto, Y. Nemoto, S. Fujita, D. Kawasaki, R. Yamada, and N. Tawada, “A front-end converter with high reliability and high efficiency,” in Proc. IEEE Conf. Energy Convers. Congr. Expo., 2010, pp. 3216–3223.

[5] J.-S. Lai, D. Hurst, and T. Key, “Switch-mode supply power factor improvement via harmonic elimination methods,” in Proc. IEEE 6th Annu. Appl. Power Electron. Conf. Expo., 1991, pp. 415–422.

Real time implementation of unity power factor correction converter based on fuzzy logic



In this paper an analysis and real time implementation of unity power factor correction converter (PFC) based on fuzzy logic controller is studied. A single phase AC–DC boost converter is realized to replace the conventional diode bridge rectifier. Fuzzy logic and hysteresis control techniques is implemented to improve the performance of the boost converter. The fuzzy controller is applied to DC voltage loop circuit to get better performance. The current loop is being controlled by using a PI, and hysteresis controllers. The robustness of the controller is verified via MATLAB/Simulink, the results show that the fuzzy controller gives well controller. An experiment test is implemented via a test bench based on dSPACE 1103. The experimental results show that the proposed controller enhanced the performance of the converter under different parameters variations.


  1. Power factor correction (PFC)
  2. PLL
  3. Fuzzy logic controller (FLC)
  4. Hysteresis controller
  5. DSPACE 1103


 Circuit Diagram:


Fig. 1. Single phase PFC boost converter control system

Expected Simulation Results


Fig.2. Diode Bridge input current


 Fig.3. Line Current and its harmonic spectrum using the fuzzy controller for DC bus


Fig.4. DC bus voltage based on fuzzy controller



Fig.5. PFC input current


 In this paper, a single-phase PFC converter DC voltage loop has been analysed. The fuzzy logic controller technique is implemented to improve the performance of the PFC converter, it is robust and efficient. Matlab/Simulink has been used to simulate the proposed techniques with successful result, the dSPACE 1103 have been used to implement the fuzzy controller in real-time. Simulation results have been presented and confirmed by the real time tests; in the same time, high efficiency is obtained. The proposed controller applied to the unity power factor give better results, a reduced harmonic distortion, and robustness control during parameter variations.


[1] M. Malinowski, M. Jasinski, M.P. Kazmierkowski, “Simple direct power control of three-phase PWM rectifier using space-vector modulation (DPCSVM)”, IEEE Transactions on Industrial Electronics (2004) 447–454

[2] Masashi O., Hirofumi M. “An AC/DC Converter with High Power Factor”, IEEE Transaction on Industrial Electronics, 2003, Vol 50, No. 2, pp. 356–361.

[3] Kessal A, Rahmani L, Gaubert JP, Mostefai M. “Analysis and design of an isolated single-phase power factor corrector with a fast regulation”. Electr Power Syst Res 2011; 81:1825–31.

[4] Guo L, Hung JY, Nelms RM. “Comparative evaluation of sliding mode fuzzy controller and PID controller for a boost converter.” Electr Power Syst Res 2011; 81:99–106.

[5] Kessal A, Rahmani L, Gaubert JP, Mostefai M. “Experimental design of a fuzzy controller for improving power factor of boost rectifier”. Int J Electron 2012;99 (12):1611–21.