Scholarly article on topic 'A single-stage voltage sensorless power factor correction converter for LED lamp driver'

A single-stage voltage sensorless power factor correction converter for LED lamp driver Academic research paper on "Electrical engineering, electronic engineering, information engineering"

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{"LED lamp" / PFC / "Total harmonic distortion (THD)" / "Voltage sensorless" / "Zero-crossing detector"}

Abstract of research paper on Electrical engineering, electronic engineering, information engineering, author of scientific article — Mahmoud S. Abd El-Moniem, Haitham Z. Azazi, Sabry A. Mahmoud

Abstract Light-emitting diode (LED) technology presents an effective and robust solution to decrease the energy demand. In this paper, a power factor correction (PFC) converter is proposed to solve the problems that appear when using LED lamps, such as reducing harmonic currents and reshaping the input current to be a sinusoidal waveform without using line voltage sensor, so the total cost can be reduced and increasing the efficiency. Thus, this technique is considered a simple and easy method which reduces the number of sensors required and achieves the noise isolation between the power circuit and the controller. Also, the proposed method is implemented using a zero-crossing processing, which allows a greater accuracy than other methods. Simulation and experimental results demonstrate the effectiveness and feasibility of the proposed circuit which show that the proposed control method has low inrush input current, high power factor (near unity), and fast dynamic response under transient operation. Also, a sinusoidal current waveform under a non-sinusoidal input voltage condition can be achieved.

Academic research paper on topic "A single-stage voltage sensorless power factor correction converter for LED lamp driver"

A] "

Alexandria Engineering Journal (2013) 52, 643-653

FACULTY OF ENGINEERING ALEXANDRIA UNIVERSITY

Alexandria University Alexandria Engineering Journal

www.elsevier.com/locate/aej www.sciencedirect.com

ORIGINAL ARTICLE

A single-stage voltage sensorless power factor correction converter for LED lamp driver

Mahmoud S. Abd El-Moniem a *, Haitham Z. Azazi b, Sabry A. Mahmoud c

a Petroleum Marine Services Company, Alexandria, Egypt

b Department of Electrical Engineering, Faculty of Engineering, Menoufia University, Egypt c Faculty of Engineering, Menoufia University, Egypt

Received 23 April 2013; revised 16 July 2013; accepted 18 July 2013 Available online 20 August 2013

KEYWORDS

LED lamp; PFC;

Total harmonic distortion (THD);

Voltage sensorless; Zero-crossing detector

Abstract Light-emitting diode (LED) technology presents an effective and robust solution to decrease the energy demand. In this paper, a power factor correction (PFC) converter is proposed to solve the problems that appear when using LED lamps, such as reducing harmonic currents and reshaping the input current to be a sinusoidal waveform without using line voltage sensor, so the total cost can be reduced and increasing the efficiency. Thus, this technique is considered a simple and easy method which reduces the number of sensors required and achieves the noise isolation between the power circuit and the controller. Also, the proposed method is implemented using a zero-crossing processing, which allows a greater accuracy than other methods. Simulation and experimental results demonstrate the effectiveness and feasibility of the proposed circuit which show that the proposed control method has low inrush input current, high power factor (near unity), and fast dynamic response under transient operation. Also, a sinusoidal current waveform under a non-sinusoidal input voltage condition can be achieved.

© 2013 Production and hosting by Elsevier B.V. on behalf of Faculty of Engineering, Alexandria

University.

1. Introduction

* Corresponding author. Tel.: +20 1221142507. E-mail addresses: Smach_2009@yahoo.com (M.S. Abd El-Moniem), Haitham_azazi@yahoo.com (H.Z. Azazi), Sabry_abdellatif@yahoo. com (S.A. Mahmoud).

Peer review under responsibility of Faculty of Engineering, Alexandria

While Edison is credited with the development of the first commercially practical incandescent lamp in order to improve the lifestyle, conventional lighting sources have low efficiency and high energy consumption [1]. One of the key motivations for the recent development in LED lighting is the possibility for increasing efficiency and light output. LEDs are gradually replacing the conventional lighting sources due to their numerous advantages such as [2-4]:

• High efficiency which can emit more light per watt than incandescent lamps.

University.

Production and hosting by Elsevier

1110-0168 © 2013 Production and hosting by Elsevier B.V. on behalf of Faculty of Engineering, Alexandria University. http://dx.doi.Org/10.1016/j.aej.2013.07.002

Nomenclature

R ideal resistance Vref reference voltage

L boost inductor vcontrol the controlled scaling factor of the rectified voltage

D diode Vrms RMS value of the input voltage

S MOSFET (Switch) Vo load voltage

Vs supply voltage Vo(mean) mean load voltage

is supply current Io load current

Vin(t) the rectified voltage Vf forward voltage drop for LED lamp

Vin{t) the estimated input voltage xline angular line frequency

il inductor (rectified) current

iref reference current

• No ultra-violet (UV) or infrared (IR) output.

• Have a relatively long useful life, c. 100,000 h which is more than 10 times that of compact fluorescent lamps (CFLs).

• Can very easily be dimmed either by pulse-width modulation or lowering the forward current.

• LED lamp module is composed of many LEDs, when one LED fails there are many more for back-up.

• They can be dimmed smoothly from full output to off.

• Extremely robustness, those are difficult to damage with external shock, unlike conventional lamps, which are fragile.

• Small in size.

• No external reflector.

Like conventional PN junction diodes, LEDs are current-dependent devices with their forward voltage drop VF, depending on the semiconductor compound (their light color) and on the forward biased LED current. Fig. 1 presents the I-V characteristic curves showing the different colors available [5].

LEDs are operated from a low voltage DC supply. In general lighting applications, the LED lamps have to operate from universal AC input, so an AC-DC converter is needed to drive the LED lamp [6]. The efficient drive not only performs unity power factor (PF), but also regulates LED current [7].

The rectifier with filter capacitor is called a conventional AC-DC utility interface. Although a filter capacitor signifi-

Figure 1 I-V characteristics curves for different colors available.

cantly suppresses the ripples from the output voltage, it introduces distortions in the input current and draws current from the supply discontinuously, in short pulses [8]. This introduces several problems including reduction in available power, and the line current becomes non-sinusoidal which increases the total harmonic distortion (THD) and increases losses. This results in a poor power quality, voltage distortion, and poor PF at input ac mains [9-11].

With the development of PFC converters, a sinusoidal line current can be made in phase with the line voltage, and this PFC circuit achieves the requirements of the international harmonic standards. For all lighting products and input power higher than 25 W, AC-DC LED drivers must comply with line current harmonic limit set by IEC61000-3-2 class C [12]. Single-stage PFC topologies are the most suitable converters for lighting applications, as PFC and regulator circuits can be merged together. They have high efficiency, a near unity PF, simple control loop, and a small size. In reality, the switching frequency is much higher than the line frequency, and the input AC current waveform is dependent on the type of control being used [13]. The inductor is assumed to be operated in continuous conduction mode (CCM) which is implemented using hysteresis current control method. Operation is possible throughout the line-cycle, so the input current does not has harmonic distortions [14,15].

There are various PFC control algorithms using input voltage sensorless approach [16-19]. A simple control method using current law has been described in [16,17] by using only an instantaneous input current and a proportional gain in controlling the dc link voltage constantly. However, these methods did not take in consideration the current compensation, so stable operation in the transition state and protect devices from overcurrent cannot be achieved. Nonlinear-control methods [18,19] provided good solutions to implement the control integrated circuit (IC) design effectively without using input voltage sensor. However, the output voltage regulation will be affected due to lack of input voltage information.

In this paper, boost PFC converter is used to drive LED lamps from universal AC supply due to its advantages such as [20-22]: (a) simple structure; (b) the input inductor can suppress the surging input current; and (c) the power switch is non-floating, so it is easy to design the driver circuit. An algorithm of PFC control is proposed without using line voltage sensor. The input voltage is estimated using the sensed inductor current and output voltage, which make the proposed method more simple and reliable than other methods. Also, a

Figure 2 Boost PFC based on hysteresis current mode control for LED lamp driver.

zero-crossing detector is used to make the proposed method more accurate than other methods when using distorated supply voltage. The input current has a sinusoidal waveform.

2. PFC control for LED lamp

Fig. 2 illustrates the boost PFC converter based on hysteresis current mode control for LED lamp driver. In the outer voltage loop, the error between the sensed output voltage and the voltage reference is the input of the proportional-integral (PI) voltage controller. The output of this PI controller is the scaling factor for the rectified voltage (vcontrol). The product of the scaling factor and the rectified voltage divided by the square of the root mean square (RMS) of input voltage is the reference current, iref as in Eq. (1). The inner current loop implements hysteresis current mode control to force the inductor current to follow the reference current [23].

vcontrol ' Vm{t) , *

V --V2--^

The principle of hysteresis control is controlling the switches to be on or off as necessary to force the inductor current waveform to follow the sinusoidal reference within a given hysteresis band [24].

In boost PFC converter based on hysteresis current mode control, the inductor current is continuously compared with the reference current waveform to make the inductor current always within the upper and lower band. The error signal between the inductor and reference currents is fed to a hysteresis comparator. When the actual inductor current ft) goes above the reference current (iref) by the hysteresis band comparator, the current ramp goes down by changing the comparator state to make the boost converter switch to be off. When the actual current goes below the reference current by the hysteresis band comparator, the current ramp goes up by changing the comparator state again to make the boost converter switch to be on [24,25].

During operation of a boost converter in CCM, the inductor current (il) never becomes zero during a commutation cycle.

3. Proposed PFC control technique

This technique proposes a PFC control without using line voltage sensor to achieve a near unity PF for single phase rectifier.

In boost PFC, shown in Fig. 2, the line voltage is sensed then rectified using absolute unit to the rectified voltage, Vin(t),

that is one of the inputs to the multiplier to have the reference current (iref) as in Eq. (1). In the proposed PFC, the rectified voltage can be estimated without using line voltage sensor depending on the sensed inductor current and output voltage as follows:

The boost converter assumes two distinct states [23,26]:

The on-state, in which the switch (S) in Fig. 2, is closed, and then, there is a constant increase in the inductor current.

So the estimated input voltage Vin (t) can be obtained as:

'(t)~Ld±

The off-state, in which the switch (S) in Fig. 2, is made open and the inductor current now flows through the diode D, the capacitor C, and the load (LED string). In this state, the energy that has been accumulated in the inductor transferred to the capacitor and LED String.

So the estimated input voltage Vn (t) can be obtained as:

Vn (t)= V0 + L

After that, the estimated input voltage is fed to a zero-crossing detector, and the output of this detector is fed to sine wave look up table which provide a rectified input voltage with a unity amplitude. The proposed control method without using line voltage sensor is shown in Fig. 3.

The zero-crossing detector is used with the proposed control method in order to achieve a good performance under distorted supply voltage. While the supply voltage has a distortion waveform, the zero-crossing detector does not affected with the shape of supply voltage waveform, so a sine wave voltage waveform with unity amplitude can be achieved even a non-sinusoidal supply voltage waveform is used, so this approach has a simple control compared with other methods.

4. Simulation results

■a c

to tl) ra .2

400 300 200 100 0 -100 -200 -300 -400

0.3 0.305 0.31 0.315 0.32 0.325 0.33 0.335 0.34

Time in Sec.

Figure 4 Input voltage and current for ideal supply voltage.

__________V(V)-- »(Amp.)—

/ /r Xy

0.2 0 -0.2

0.3 0.305 0.31 0.315 0.32 0.325 0.33 0.335 0.34

Time in Sec.

Figure 5 Input current waveform.

The control algorithm of the proposed control method has been developed and simulated using the MATLAB/SIMUL-NK software. The simulation allows investigation of both transient and steady-state operations for the proposed method which can also show the reducing in supply current harmonic distortion. The system parameters are reported in Appendix A.

The steady-state supply voltage (Vs) and the supply current (is) waveforms are shown in Fig. 4. It is clear that the input current is in phase with the input voltage for boost PFC converter without using line voltage sensor.

The steady-state simulation results of input current and its harmonic spectrum for hysteresis current control method are

Figure 3 Proposed control method without using line voltage sensor.

110 100 90 80 70 60 50 40 30 20 10 0

1 1 THD=-3.83% -PE=û.999j2-_____

_ _ L_m_J

8 10 12 14

Harmonic order

d n a e ra

300 200 100 0 -100 -200

WV-)- 1 1

Figure 6 Harmonics spectrum of supply current.

0.3 0.305 0.31 0.315 0.32 0.325 0.33 0.335 0.34

Time in Sec.

Figure 9 Input voltage and current for distorted supply voltage.

---¿-Vine !

AmpJ-- - -Aref*

7/" L \\ -VI

0.3 0.305 0.31 0.315 0.32 0.325 0.33 0.335 0.34

Time in Sec.

Figure 7 Rectified voltage, rectified current and reference current.

■S 30

-------- .-Io-tli /

0.3 0.305 0.31 0.315 0.32 0.325 0.33 0.335 0.34

Time in Sec.

Figure 8 Load voltage and current.

shown in Figs 5 and 6, respectively. From these results, it is clear that the input current is nearly sinusoidal, and its total harmonic distortion is very low, 3.83%, and the PF is 0.9992.

The rectified voltage (Vin), the rectified current ft), and the reference current (iref) simulation waveforms are shown in

Fig. 7. Simulation shows clearly that the rectified current is always very close to the reference current for proposed method.

The load voltage and current waveforms are shown in Fig. 8, which illustrate the very small ripples in both of them that do not have any effect on LEDs operation.

The steady-state supply voltage (Vs) and current ft) waveforms for the proposed method under distorted input voltage are shown in Fig. 9. It is shown that the input current has a sinusoidal waveform and being in phase with the input voltage without using line voltage sensor.

The simulation results of supply voltage and current due to + 25% step change in the input voltage for the proposed control method, without using line voltage sensor, are shown in Figs. 10 and 11, respectively. It is clear that a sinusoidal input current waveform is maintained under the input voltage changes.

The simulation results of load voltage and current due to + 25% step change in the input voltage for the proposed method are shown in Figs. 12 and 13, respectively. As seen from these figures, the decrease in the input voltage makes an increase in the line current and vice versa because the power is constant. The change in load voltage and current due to the change in the input voltage has a small duration (about 0.05 s), and then, the load voltage and current return to their initial steady-state values. Also, the error in load voltage due

0.8 0.9 1

Time in Sec.

Figure 10 Variation in supply voltage due to +25% step change in the input voltage.

0.8 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8.

0.8 0.9 1

Time in Sec.

Figure 11 Variation in supply current due to +25% step change in the input voltage.

~l-1-1-1-1-1-r

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3

Time in Sec.

Figure 14 Error in load voltage due to + 25% step change in the input voltage.

60 59 58 57

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3

Time in Sec.

Figure 12 Variation in load voltage due to +25% step change in the input voltage.

O ■a

Vref (V) Vo( V)

Io*20 (Amp.

V r

AVAVMAV MVMMAMVI t

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3

Time in Sec.

Figure 15 Variation in load voltage and current due to negative and positive step change in reference voltage.

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3

Time in Sec.

0.5 0.6 0.7

0.8 0.9 1

Time in Sec.

1.1 1.2 1.3

Figure 13 Variation in load current due to + 25% step change in the input voltage.

Figure 16 Error in load voltage due to negative and positive step change in reference voltage.

to +25% step change in input voltage is shown in Fig. 14 which indicates that the proposed PFC control method has a fast response.

The variation in load voltage and current due to negative and positive step change in reference voltage (from 60 V to 56 V) is shown in Fig. 15 without using line voltage sensor. It is observed that the load current follows the load voltage which follows the desired reference voltage, so the dynamic responses of load voltage and load current for negative and positive step change in reference voltage are fast. Also, the error in load voltage due to negative and positive change in reference voltage (from 60 V to 56 V) is shown in Fig. 16 which indicates the fast response for the proposed PFC control method under these variations in reference voltage.

5. Experimental results

With the objective of evaluating the employed topology, a laboratory prototype is setup. The block diagram of the experimental setup and a real view of the complete control system are shown in Figs. 17 and 18, respectively. The main components of the system which labeled as in Fig. 18 are listed in Table 1. The proposed PFC control is done on a digital signal processor board (DS1104) plugged into a computer. The control algorithm is executed by "Matlab/simulink,'' and downloaded to the board through host computer. The output of the board is logic signal, which is fed to IGBT through driver and isolation circuits.

5.1. LED lamp driver without PFC circuit

The experimental results of supply voltage and the supply current waveforms in steady-state in case of using single phase rectifier without PFC circuit to drive the LED lamps are shown in Fig. 19. It is illustrated from this figure that the high

Figure 18 Experimental setup of PFC circuit for LED lamps.

distorted input current has peak value in short duration, and there are voltage dips in the supply voltage due to the high value of input current.

The experimental results of the harmonics spectrum of the supply current and voltage are shown in Figs. 20 and 21, respectively. It is observed that the supply current has a high THD of 87.94% with a low PF of 0.75, and the supply voltage has THD of 6.6% as using single phase rectifier without PFC circuit to drive LED lamps.

The experimental results of the load voltage and current waveforms are shown in Fig. 22. It is observed that the load voltage and load current has a nearly DC value with a small ripples.

5.2. LED lamp driver with PFC circuit using proposed control technique

The steady-state experimental results of the supply voltage and supply current for single phase rectifier with PFC circuit

dSPACE DS1104

Figure 17 Block diagram of the experimental setup of PFC for LED lamps.

Table 1

Label Component Label Component

PC Personal computer H Voltage and current transducers

I DSP interface circuit R Load (LED lamps)

B Base drive circuit C Capacitor

P.S. All other power suppliers L Inductor

P Variable AC power supply D Fast recovery diode

T Single phase full wave bridge rectifier S IGBT

■a c

to tl) CT

400 300 200 100 0 -100 -200 -300 -400

2 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08

Time in Sec.

Figure 19 Supply voltage and current waveforms.

Vs[100 V/div] is[1Amp /div]

________ ________

c e 80

m a 70

THD PF=0 =87.9 75 4%___

I ------ ------ ------- ------- ------ ------ ------

1 1 ■ ■ m _

8 10 12 14

Harmonic order

110 100 90 80 70 60 50 40 30 20 10 0

■ ■ _ _ _ _ _ _

2 4 6 8 10 12 14 16 18 20

Harmonic order

d n a e

Figure 21 Harmonics spectrum of supply voltage.

70 60 50 40

Vo [10V /div]

Io[ 0.5Amp./div]

Figure 20 Harmonics spectrum of supply current.

2 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08

Time in Sec.

Figure 22 Load voltage and current waveforms.

without using line voltage sensor to drive LED lamps are shown in Fig. 23. It is shown that the supply current has a nearly sinusoidal waveform, and it is in phase with the input voltage.

The experimental result of the harmonics spectrum of the supply current is shown in Fig. 24. It is indicated that, with using PFC circuit using proposed control technique, the input current has a low harmonic contents (THD) of 7.77% with high PF of 0.996.

The experimental results of the rectified current and reference current under the steady-state for the proposed method are shown in Fig. 25. It is observed that the rectified current is very close to reference current.

The steady-state experimental results of the load voltage and current are shown in Fig. 26. It is clear that the load voltage and current has a DC value with very small ripples and the LED lamps do not affected with these ripples.

The experimental results of the variation in the load voltage and load current due to negative step change in reference voltage (from 60 V to 55 V) and positive step change in reference voltage (from 60 V to 65 V) are shown in Fig. 27. It is shown that the load voltage follows the desired reference voltage, and hence, the load current follows the load voltage.

The experimental results of supply voltage and current due to +25% step change in the input voltage for the proposed

re 200

o -100

Π- -200

Vs [100 V/div] is[0.5A Lmp./d v]

jT № -jr- - ~~Jr

2 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08

Time in Sec.

Figure 23 Supply voltage and current waveforms.

§ 40 30 3 20 ° 10 0

JéJL Will

V , [10V/t iv]

Io[0 .6Amp /div]

2 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08

Time in Sec.

Figure 26 Load voltage and current waveforms.

110 100 90 80 70 60 50 40 30 20 10 0

1 i i • ■

8 10 12 14

Harmonic order

Figure 24 Harmonics spectrum of supply current.

2.01 2.02

2.03 2.04 2.05

Time in Sec.

2.06 2.07 2.08

Figure 25 Rectified current and reference current waveforms.

control method are shown in Figs. 28 and 29, respectively. It is clear that a sinusoidal input current waveform is maintained under the change in supply voltage, which is illustrated in the zoom of the variation in the supply voltage and current (from 0.95 to 1.2 s) under +25% step change in the supply voltage as shown in Fig. 30.

d n a e ra

0 1 2 3 4 5

Time in Sec.

Figure 27 Variation in load voltage and current due to negative and positive step change in reference voltage.

400 300 200

Time in Sec.

Figure 28 Variation in supply voltage due to «25% step change in the input voltage.

The experimental results of load voltage and current due to «25% step change in the input voltage for the proposed

0.8 0.6 0.4 0.2 0

Time in Sec.

Figure 29 Variation in supply current due to +25% step change in the input voltage.

2.5 2 1.5 1

-0.5 -1 -1.5 -2 -2.5

-3 — 0.5

Time in Sec.

Figure 32 Error in load voltage due to + 25% step change in the input voltage.

400 . 300

Vs [100 V/div]

1.05 1.1

Time in Sec.

Figure 30 Zoom of the variation in supply voltage and current due to + 25% step change in the input voltage.

«iMfrnnw^ 'WW

Amp./div]

Time in Sec.

Figure 31 Variation in the load voltage and current due to + 25% step change in the input voltage.

method are shown in Fig. 31. The change in load voltage and current due to the change in the input voltage has a small duration then the load voltage and current return to their initial steady-state values. Also, the error in load voltage due to + 25% step change in input voltage is shown in Fig. 32 which indicates that the proposed PFC control method has a fast response.

6. Conclusions

In this paper, a new control technique without using line voltage sensor to drive the LEDs current and produces high PF has been presented. This technique is characterized by its simplicity and its reliability to estimate the rectifier voltage compared with other PFC control algorithms. Also, a low cost digital controller can be used. The rectifier voltage is estimated based on sensed inductor current and output voltage. Simulation results showed that the boost PFC converter without using line voltage sensor has a nearly sinusoidal input current with low THD and high PF. Also a nearly sinusoidal input current can be achieved under supply voltage distortion. Also from these results, a better and accurate performance can be achieved due to use a zero-crossing detector. Better dynamic performance for positive and negative change in the input and reference voltages can be achieved. Performance of the proposed control technique was verified experimentally. The experimental results have approved that, the simulation results which have been illustrated by using AC-DC converter with PFC without using line voltage sensor to drive the LED lamps have a nearly sinusoidal input current waveform with low THD and high PF. Besides, a fast dynamic performance for step change in the input and reference voltages can be achieved. So, these experimental results have assured that the proposed control technique is good. There are slight differences between the simulation and experimental results because in simulation results the supply voltage has an ideal sine waveform but, in experimental results supply voltage is not ideal sine waveform. Also, the simulation results are done with sampling time 1e~5 s. But, the experimental results are done with dSPACE (DS1104) using sampling frequency 10 kHz (sampling time is 1e~4 s).

Appendix A

The simulation and the experimental results for the proposed method are taken with the following specifications:

References

[1] James A. Worthey, How White Light Works, LRO Lighting Research Symposium, Light and Color, 2006.

[2] H.J. Chiu, Y.K. Lo, A high-efficiency dimmable LED driver for low power lighting applications, IEEE Transactions on Industrial Electronics 57 (2) (2010) 735-743.

[3] Huang-Jen Chiu et al, LED backlight driving system for large-scale LCD panels, IEEE Transactions on Industrial Electronics 54 (5) (2007) 2751-2769.

[4] A.R. Brown, D.D.C. Bradley, J.H. Burroughes, R.H. Friend, N.C. Greenham, P.L. Burn, A.B. Holmes, A.M. Kraft, Light-emitting diodes based on conjugated polymers, in: IEE Colloquium on Conducting Polymers and Their Applications, 1992, pp. 2/1-2/4.

[5] S.Y. Lee, J.W. Kwon, H.S. Kim, M.S. Choi, K.S. Byun, New design and application of high efficiency LED driving system for RGB-LED backlight in LCD display, in: 37th IEEE power electronics specialists conference, PESC '06, Jeju, Korea, 18-22 June 2006, pp.1-5.

[6] Jorge Garcia, Marco A. Dalla-Costa, et al, Dimming of high-brightness LEDs by means of luminous flux thermal estimation, IEEE Transactions on Power Electronics 24 (2) (2009) 11071114.

[7] G. Sauerlander, D. Hente, H. Radermacher, E. Waffenschmidt, J. Jacobs, Driver electronics for LEDs, in: Industry Applications Conference, 2006. 41st IAS Annual Meeting. Conference Record of the 2006 IEEE, vol. 5, Tampa, Florida, USA, October 2006, pp. 2621-2626.

[8] F. Beltrame, L. Roggia, L. Schuch and J. R. Pinheiro, A comparison of high power single-phase power factor correction pre-regulators, in: IEEE International Conference on Industrial Technology (ICIT), Vina del Mar, Chile, 2010, pp. 625-630.

[9] F. Chen, D. Maksimovic, Digital control for improved efficiency and reduced harmonic distortion over wide load range in boost PFC rectifiers, IEEE Transactions on Power Electronics 25 (10) (2010) 2683-2692.

[10] Ali M. Eltamaly, A novel harmonic reduction technique for controlled converter by third harmonic current injection, Electric Power Systems Research 91 (2012) 104-112.

[11] Vishnu Murahari Rao, Amit Kumar Jain, Kishore K. Reddy, Aman Behal, Experimental comparison of digital

implementations of single-phase PFC controllers, IEEE Transactions on Industrial Electronics 55 (1) (2008) 67-78.

[12] Compliance Testing to the IEC 1000-3-2 (EN 61000-3-2) and IEC 1000-3-3 (EN 61000- -3) Standards, Application Note 1273, Hewlett Packard Co., December 1995.

[13] Klaus Raggl, Thomas Nussbaumer, Gregor Doerig, Juergen Biela, Johann W. Kolar, Comprehensive design and optimization of a high-power-density single-phase boost PFC, IEEE Transactions on Industrial Electronics 56 (7) (2009) 25742587.

[14] Konstantinos Georgakas, Athanasios Safacas, Switching frequency determination of a bidirectional AC-DC converter to improve both power factor and efficiency, Electric Power Systems Research 81 (7) (2011) 1572-1582.

[15] Grace Chu, Chi K. Tse, Siu Chung Wong, Siew-Chong Tan, A unified approach for the derivation of robust control for boost PFC converters, IEEE Transactions on Power Electronics. 24 (2009) 2531-2544.

[16] Y. Notohara, T. Suzuki, T. Endo, Y. Um, K. Tamura, Controlling power factor correction converter single-phase AC power source without input voltage sensor, in: International Power Electronics Conference (IPEC 2010), Sapporo, Japan, June 2010, pp. 431-436, 21-24.

[17] Barry Mather, Bhask Ramachandran, A digital PFC controller without input voltage sensor, in: Twenty-Second Annual IEEE Applied Power Electronics Conference, APEC 2007, Anaheim, California, February 25 2007, pp. 198-204.

[18] D. Maksimovic, Yungtaek Jang, R. W Erickson, Nonlinear-carrier control for high-power-factor boost rectifier, IEEE Transactions on Power Electronics 11 (4) (1996) 578-584.

[19] Mathew Min Chen, v.A. Jian Sun, Nonlinear current control of single-phase PFC converters, IEEE Transactions on Power Electronics 22 (6) (2007) 2187-2194.

[20] Jung-Min Kwon, Woo-Young Choi, Bong-Hwan Kwon, Cost-effective boost converter with reverse-recovery reduction and power factor correction, IEEE Transactions on Industrial Electronics 55 (1) (2008) 471-473.

[21] Abdelhalim Kessal, Rahmani Lazhar, Jean-Paul Gaubert, Mostefai Mohammed, Analysis and design of an isolated single-phase power factor corrector with a fast regulation, Electric Power Systems Research 81 (9) (2011) 1825-1831.

[22] Antonio Lázaro, Andrés Barrado, Marina Sanz, Vicente Salas, Emilio Olías, New power factor correction AC-DC converter with reduced storage capacitor voltage, IEEE Transactions on Industrial Electronics 54 (1) (2007) 384-397.

[23] H.Z. Azazi, E.E. EL-Kholy, S.A. Mahmoud and S.S. Shokralla, Digital control of boost PFC AC-DC converters with predictive control, in: 14th International Middle East Power system Conference (MEPC0N'10), Egypt, December 2010, pp 721-727.

[24] Ahmet Karaarslan, Ires Iskender, Analysis and comparison of current control methods on bridgeless converter to improve power quality, International Journal of Electrical Power and Energy Systems 51 (2013) 1-13.

[25] H.Z. Azazi, E.E. EL-Kholy, S.A. Mahmoud, S.S. Shokralla, Review of passive and active circuits for power factor correction in single phase, low power AC-DC converters, in: 14th International Middle East Power system Conference (MEPC0N'10), Egypt, December 2010, pp. 217-224.

[26] Umamaheswari, V. Venkatachalam, Single phase converters for power factor correction with tight output voltage regulation, International Journal of Emerging Technology and Advanced Engineering 3 (2) (2013) 516-521.

Parameter Symbol Value

Supply nominal voltage Vs 220 Vrms

Line frequency F 50 Hz

Step down voltage transformer Tr 220:24 Vrms

Inductor L 3mH

DC link capacitor C 3000 iF

LEDs power Po 60 W

Load voltage Vo 60 Vdc

Load current Io 1 Adc

Load contains three parallel branches, each branch has 19 LEDs and the current in each LED is 350 mA.