Performance Analysis of Single-Stage LED Buck Driver Topologies for Low-Voltage DC Distribution Systems

Abstract

The demand for lean protein is the main reason for raising domesticated birds in poultry farms for the purpose of farming meat or eggs for food. In these poultry farms, artificial lighting system is an essential factor for the success of the commercial production of egg layers and broilers. Lighting loads connected to the existing AC system requires DC power. Nearly 25% of the total power consumed in India is by lighting loads. Therefore, low-voltage DC distribution system is the new requirement of electrical network to improve energy conservation. In this paper, an energy efficient single-stage LED driver topology is proposed as a better alternative to fluorescent lights used in poultry farms. The proposed topology is a phase-shifted buck converter with reduced size of passive components. The converter is mathematically modelled and designed for a power of 24 W LED lights. An experimental prototype is developed for the proposed converter and the results are validated in terms of cost, energy savings, and energy efficiency with various other LED driver topologies like conventional buck converter and interleaved buck converter. Further to justify the outcome of the proposed LED driver, a case study is also done for poultry farms.

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Performance Analysis of Single-Stage LED Buck
Driver Topologies for Low-Voltage DC Distribution
Systems
R. Srimathi & S. Hemamalini
To cite this article: R. Srimathi & S. Hemamalini (2019): Performance Analysis of Single-Stage
LED Buck Driver Topologies for Low-Voltage DC Distribution Systems, IETE Journal of Research,
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IETE JOURNAL OF RESEARCH
https://doi.org/10.1080/03772063.2019.1682072
Performance Analysis of Single-Stage LED Buck Driver Topologies for
Low-Voltage DC Distribution Systems
R. Srimathi and S. Hemamalini
School of Electrical Engineering, Vellore Institute of Technology, Chennai, Tamil Nadu 600127, India
ABSTRACT
The demand for lean protein is the main reason for raising domesticated birds in poultry farms for the
purpose of farming meat or eggs for food. In these poultry farms, artificial lighting system is an essen-
tial factor for the success of the commercial production of egg layers and broilers. Lighting loads
connected to the existing AC system requires DC power. Nearly 25% of the total power consumed
in India is by lighting loads. Therefore, low-voltage DC distribution system is the new requirement
of electrical network to improve energy conservation. In this paper, an energy efficient single-stage
LED driver topology is proposed as a better alternative to fluorescent lights used in poultry farms.
The proposed topology is a phase-shifted buck converter with reduced size of passive components.
The converter is mathematically modelled and designed for a power of 24 W LED lights. An exper-
imental prototype is developed for the proposed converter and the results are validated in terms
of cost, energy savings, and energy efficiency with various other LED driver topologies like conven-
tional buck converter and interleaved buck converter. Further to justify the outcome of the proposed
LED driver, a case study is also done for poultry farms.
ARTICLE HISTORY
Received
KEYWORDS
LED driver; Phase-Shifted
Buck Converter (PSBC);
digital controller; dimming
control; energy savings
1. INTRODUCTION
Lighting schedule in poultry farms have immense poten-
tial to impact the welfare and productivity of poultry [1].
Breeding farms have specic requirements on the light
intensity for brooding and for the growing of a ock. The
general requirement is approximately 20 lux and above
for brooding and 5–8 lux for growing [2]. Incandescent
lamps, uorescent lamps, halogen lamps, metal halide,
and high pressure sodium lamps are used for lighting
program [3]. However, in order to have energy ecient
indoor lighting luminaries, LEDs are preferred due to
their long lifetime and luminous ecacy, etc. [4]. There-
fore, it becomes mandatory to design a suitable indoor
lighting system to suit the poultry farm requirements in
the most energy ecient and economic manner. Nearly
0.5% (4000 GWh) of the total energy consumed in India
is utilized by poultry farms [5].
ThedrivertopologiesaredevelopedeitherasAC–DC
or DC–DC based on the availability of power source.
LED driver topologies are classied as single stage [6],
two stage [7], and three stage [8] based on power con-
version. Single-stage topologies are used in commer-
cial and domestic applications where as two and three
stagetopologiesareusedinplaceswherecostisnota
concern. In AC–DC driver topologies, the lifetime of
LED driver is limited because of the presence of elec-
trolytic decoupling capacitor [9] between AC source and
DC lighting load. To enhance the lifetime of drivers,
capacitor-less driver topologies [10–12]havebeenpre-
sented. These topologies require high-performance com-
plex power factor correction control circuits so as to meet
the industry-specic standards such as IEC610000-3-2.
Consequently, the need for electrolytic capacitors is elim-
inated when lights are powered by low-voltage DC [13].
Therefore, DC distribution for lighting system will be
a better alternative due to their high eciency, fewer
conversion stages, enhanced reliability and low system
cost [14].
Conventional non-isolated DC–DC driver topology
require current balancing technique as large number of
LEDsareconnectedinseriesandparalleltoachieve
required luminance value [15]. Series connecting struc-
ture is easy to balance current, whereas it is dicult
for multiple strings [16].Useoflinearregulators[17],
magnetic components [18], and capacitor impedance
methods [19] are some of the current balancing tech-
niques. However, certain applications require dimming
of LEDs by pulse width modulation (PWM) technique
[20–23]. Integrating the driver, controller and LED light
in a single chip can have an impact on decreasing the
© 2019 IETE

2 R. SRIMATHI AND S. HEMAMALINI: PERFORMANCE ANALYSIS OF SINGLE-STAGE LED BUCK DRIVER TOPOLOGIES
cost of the driver [24]. Multiphase interleaved buck con-
verter [IBC] [25] topology in power supplies oers sev-
eral advantages such as ripple cancellation, good thermal
distribution, and small lter size. But, it has complex cir-
cuit with several power stages with a diculty to control
current in each phase [26].
The key objective of this paper is to design and develop a
single stage, single channel, LED driver for low-voltage
DC distribution system. The proposed converter con-
sists of a single inductor, two power switches, one diode,
and a capacitor. The two power switches are operated
in phase shift such that the inductor is charged and dis-
charged twice in one switching period (Ts), therefore the
frequency of inductor current (fsL) is twice that of the
switching frequency (fs). This in turn reduces the size
of the inductor and output lter size. Total switching
loss, conduction losses, switching stress of the switches
remainssameasthatofconventionalbuckconverter.
Moreover, by using fast recovery diodes the eciency of
the converter is enhanced.
The main focus of this paper is to reduce cost and size
and increase the reliability of the LED driver. The pro-
posed topology is mathematically modelled, designed,
and developed. A closed loop control strategy is devel-
oped to control the current through the LED. The per-
formance of the proposed topology is compared with
conventional buck converter (CBC) and interleaved buck
converter (IBC) topologies. A hardware prototype of all
thetopologiesisdevelopedforapowerratingof24W.
The hardware implementation, experimental set up, cost
analysis, and real-time eciency results of the proposed
converterisvalidatedbyacasestudyinapoultryfarm.
The case study discusses the retrot procedure, instal-
lation cost, and energy savings in a commercial poultry
farm. In addition, a lighting design for the existing unit
with the LED lights is developed using AUTOCAD and
DIAlux software.
2. ANALYSIS OF PHASE-SHIFTED BUCK
CONVERTER
The proposed converter is analysed, designed, and com-
pared with the existing topologies like CBC [27,28]and
IBC [29,30] in terms of component count and size of
the passive elements in this section. The circuit diagram
for the LED driver topologies are shown in Figure 1(a,b),
whereas the proposed converter is shown in Figure 1(c).
In Figure 1(a),theCBCconverterhasonlyoneswitchand
it is turned “ON” and “OFF” once for a given switching
period Ts.Duringthisperiod,theinductorLischarged
Figure 1: Circuit diagram for LED driver topologies. (a) CBC. (b)
IBC, and (c) PBC.
and discharged once. The IBC converter in Figure 1(b)
has two parallel CBC converters. Each parallel CBC con-
verter is termed as phase “n” and each phase contributes
equallyfortheloadcurrent.TheswitchesinIBCareoper-
ated in phase shift by 360◦/nwith two operating modes.
During Mode I (S1-ONandS2-OFF),theinductorL1
is charged and L2isdischarged,whereasforModeII(S2
-ONandS1-OFF),theinductorL2is charged and L1is
discharged. The inductance in each phase is half that in
CBC, but the eective inductance is same as CBC. How-
ever, the proposed converter consists of only one inductor
with reduced size and it is explained below.
The proposed converter consists of two parallel con-
nected switches operated in phase-shifted scheme. The
switching pattern of the proposed converter is phase
shifted by 360◦/(m),wheremis the number of switches
connected in parallel for each phase (n). The two power
switches are operated in phase shift such that the induc-
tor current has a repetition rate of twice the switching
frequency. The output voltage ripple and input current
ripple of the PSBC is mtimes the switching frequency,
thereby, reducing the size of the passive components L

R. SRIMATHI AND S. HEMAMALINI: PERFORMANCE ANALYSIS OF SINGLE-STAGE LED BUCK DRIVER TOPOLOGIES 3
and Cwhen compared with CBC. The number of induc-
tors is also reduced in the proposed converter than in
IBC. The sequence of gating signals is shown in Figure 2.
PSBC is operated in four modes and the equivalent circuit
forthemodesofoperationisgiveninFigure3.
2.1 Operation of PSBC
2.1.1 Mode 1: [0to Ts4]
In this mode, switch S1-ONandS2-OFF.Duringthis
mode, the inductor is charged by the supply voltage Vin
and the load is supplied by the source. The equivalent cir-
cuitformodeIisshowninFigure3(a). The voltage across
the inductor during this period t1is given by (2)
VL=Vin −Vo
L(1)
2.1.2 Mode 2: [Ts/4to Ts/2]
During this time interval, the switches S1and S2are OFF.
The energy stored in the inductor is discharged through
the diode (D) to the load and is shown in Figure 3(b). The
voltage across the inductor during these modes is.
VL=Vo
L(2)
2.1.3 Mode 3: [Ts/2to 3Ts/4]
During, Mode III the inductor is charged with the switch
positions being S2-ONandS1- OFF as in Figure 3(c).
Figure 2: Gating sequence of PSBC
Figure 3: Modes of operation of PSBC. (a) Mode 1 - S1-ONand
S2-OFF.(b)Mode2-S1-OFFandS2-OFF.(c)Mode3-S1-OFF
and S2-ONand(d)Mode4-S1-OFFandS2-OFF.
2.1.4 Mode 4: [3Ts/4to Ts]
The energy stored in the inductor is discharged during
this period as in Mode II and is shown in Figure 3(d).
Therefore, for one switching period, Ts, the inductor is
charged and discharged twice.
2.2 Design of PSBC
The expression for voltage gain is obtained by equating
volt–sec balance of the inductor for half of the switching
period Tsandisin(3).
Vin −Vo
Lt1=Vo
Lt2=IL(3)
where t1=D1Tsand t2=(Ts/2)−D1Tsare the switch-
inginstantsofmodes1and2,Vin and Voare the input
andoutputvoltagesandListheinductance,D1is the duty
ratio of the switch S1,respectively.Thevoltagegainfor
the proposed converter is as given in (4).
Vo
Vin
=2∗D1(4)

4 R. SRIMATHI AND S. HEMAMALINI: PERFORMANCE ANALYSIS OF SINGLE-STAGE LED BUCK DRIVER TOPOLOGIES
Similarly, the generalized expression for voltage gain for
mnumber of switches is given by
Vo
Vin
=m∗D(5)
In (5), the duty ratio of the switches are assumed to be
equal i.e.,D1=D2=D.Likewise,thecurrentgainfor
the PSBC is
Iin
Io
=m∗D(6)
where Iin and Ioaretheinputandoutputcurrentsofthe
converter. The current stress Istr througheachswitchis
given by (7)
Istr =D∗Io
m(7)
From (7), it is evident that the current stress through
the switch is reduced by m times than that of CBC.
The expression for inductance (L)isderivedfrom(8)by
substituting t1and t2in terms of ILand given as in (9).
Ts
2=t1+t2(8)
L=mD ∗Vin ∗(1−m∗D)
IL∗2∗fs
(9)
In (9), fsis the switching frequency. It is also observed
that,thevalueofLisreducedbyhalfthanthatofCBCfor
the same current ripple. This is because the inductor (L)
is charged and discharged twice for a switching period.
The capacitor for the converter is given by (11)
C=1
VoTs
0
/4IL
4dt (10)
C=mD ∗Vin ∗(1−m∗D)
32 ∗f2
s∗L∗Vo
(11)
Equations (9) and (11) are used to calculate converter
parameters for the proposed converter. PSBC is designed
in such a way that it is also suitable for high and ultra-
high-power LEDs in general lighting applications such
as oce and residential down lights, street lighting and
LED ballast, etc. For such applications, the input volt-
age can have a maximum value up to 60 V. Therefore, the
converters are designed for an input voltage of 48 V and
output voltage of 24 V. Moreover, for experimental vali-
dation in a laboratory, the converters are designed for a
medium switching frequency of 25 kHz and for an output
power of 24 W, respectively. The converter parameters are
listed in Table 1for CBC, IBC, and PSBC. It is inferred
from Table 2that, for the same input and output rat-
ing, the size of passive devices are reduced in PSBC. The
Table 1: Converter parameters
Converter L (μH)C(nF)No of parallel switches (m)
CBC 1500 470 1
IBC 750 235 1
PSBC 750 235 2
Table 2: Loss distribution in converters
Losses CBC IBC PSBC
Psws (%) 25 14 30
Pcons (%) 3 2 4
Pcond (%) 20 25 23
Pc(%) 13 26 13
Pcore (%) 39 33 30
η(%) 88 91.3 90.4
chicken broiler poultry farm need two dierent lux from
a LED light. Therefore, it is mandatory to incorporate
dimming technique in the controller sequence. The pro-
posed converter is operated in bright and dim conditions
by changing the duty ratio.
3. MATHEMATICAL MODEL OF PSBC
The stability of PWM control loops can be studied by
deriving the transfer function of the PWM converter.
There are dierent small signal modelling (SSM) meth-
ods namely state space averaging technique [31], signal
ow graph [32], switch PWM technique [33], and energy
factor [34].Amongthem,themostpreferableandsimple
method is state space averaging technique. The math-
ematical model of DC–DC converters is obtained by
considering each switching modes as linear one, though
the converter is a non-linear circuit. The dynamic equa-
tions for each operating mode of the converters taken for
consideration are obtained from the equivalent circuit in
Figure 2.Thereby,fromthedynamicequationsthegener-
alized control transfer functions Gvd and Gid are derived
by SSM and are given in (12) and (13). These equations
are used to design an appropriate controller to obtain the
desired performance objective.
Gvd =Gv
(s)1−s
ωzv (12)
Gid =Gi
(s)1+s
ωzi (13)
where Gvand Giare the open loop voltage and current
gain of the converter and are given in (14) and (15),
respectively.
Gv=Vin
2Ro
(14)
Gi=Vin
n(15)

R. SRIMATHI AND S. HEMAMALINI: PERFORMANCE ANALYSIS OF SINGLE-STAGE LED BUCK DRIVER TOPOLOGIES 5
In (14), Rois the load resistance. The zeros of the con-
trol transfer functions Gvd and Gid are given in (16)
and (17), respectively. The roots of the characteristic
equation [(s)]in(13)arethepolesofthecontroltrans-
fer functions.
ωzi =m
RoC(16)
ωzv =mn Ro
L(17)
(s)=s2
ω2
o
+s
Qωo
+1 (18)
In (18), ωois the angular corner frequency, Qis the
quality factor and is given by Q=1/2ζ,whereζis the
damping ratio. The angular frequency and quality factor
are given below,
ωo=mn
LC (19)
Q=mRonC
L(20)
3.1 Design of PID Controller
For a stable linear time invariant system, the zeros and
polesshouldbelocatedinthelefthalfoftheSplane
(LHP). From the transfer functions (10) and (11), it is
observed that the poles and zeros are located in LHP of
the s-plane. Though the poles are located in LHP of the
s-plane, a controller is required for stable operation of
the converter for input and load disturbances. The trans-
fer function (11) is used to design linear current loop
controller as shown in Figure 4.
The load current (Io) is sensed through ACS712 hall eect
current sensor. The sensed current is compared with ref-
erence current (Iref ) and the error signal is fed to the
controller (Gc(s)). The output of the controller is used
Figure 4: Schematic dual loop control for PSBC
to generate PWM signals for the MOSFET switches S1
and S2.ToregulatethecurrentthroughtheLED,thesys-
tem needs a current controller. The controller is designed
basedonthegainandphasemarginsobtainedfromthe
bode bode plot shown in Figure 5(a). The bode plot for
closed loop system is shown in Figure 5(b). It is observed
that the gain margin of the system is innite thus making
the system inherently stable.
To design a discrete transfer function for the con-
troller, digital redesign method is followed in this paper
[35]. The controller is designed in continuous domain
and its equivalent discrete transfer function is obtained
by approximation techniques. The controller is imple-
mented using PIC18F45K20 microcontroller in hard-
ware. The ow chart for programmed LED lighting is
shown in Figure 6.
4. EFFICIENCY ANALYSIS OF CONVERTERS
The eciency of a converter is estimated [36]bycalcu-
latingvariouslosscomponentslikeswitchingloss(Psw),
conduction loss (Pcon), loss in the passive components
(Pc)and core loss (Pcore ). Therefore, the total power loss
(PL) of the converter is given by
PL=Psw +Pcon +Pc+Pcore (21)
The switching (Psw) and conduction (Pcon) losses of
theconverterarecalculatedbyusingmanufacturer’s
datasheet. The equation for switching loss in MOSFET
(Psws) is given in (22) and for ultra fast recovery diode
the switching loss (Pds)is 0.
Psws =Isrmsrds +vdsIsavg +Vo
VccIDVo
(Isavg +I
2to )+Von(Isavg −I
2ton)(22)
where Isrms and Isavg are the rms and average current
through the switch, Vcc is the voltage applied to the MOS-
FET. Von,andVo are the voltage across MOSFET during
turn “ON” and turn “OFF” of MOSFET respectively. ID
is the drain current of the MOSFET and rds and vds are
the drain-source resistance and voltage of the MOSFET
[IRL520NPBF]. The conduction losses of the MOSFET
(Pcons)anddiode(Pcond) are calculated using (23) and
(24),respectively.Thelossinthepassivecomponents(Pc)
is given by (25)
Pcons =DvdsIs(23)
Pcond =(1−D)VfIf(24)
Pc=I2
LRL+I2
cRc(25)

6 R. SRIMATHI AND S. HEMAMALINI: PERFORMANCE ANALYSIS OF SINGLE-STAGE LED BUCK DRIVER TOPOLOGIES
Figure 5: Open and closed loop Current Gain Bode plots for bright condition
where Vfand Ifare the forward voltage and current of the
diode [SB5H100-E3]. In (25), RLand Rcare the parasitic
resistance of the inductor and capacitor and ILand Icare
the current through inductor and capacitor.
The core loss in the inductor (Pcore) are estimated from
thedatasheetofthemanufacturer.Thepoweroutput(Po)
is calculated from
Po=VoIo(26)
where Voand Ioare the average output voltage and cur-
rent of the converter. Accordingly, the eciency (η)ofthe
converter is calculated using (27).
η=Po
Po+PL
(27)
The power loss distribution and eciency (η)(atVin =
48V, Vo=24 V and fs=25 kHz) for bright condition is
comparedforthethreeconvertersandisgiveninTable2.
It is evident from Table 2, that for the same power rat-
ing of 24 W, the switching loss is of IBC is double that
of PSBC. But, PSBC has reduced core loss (Pcore)than
CBC and IBC. Moreover, the conduction loss of PSBC
is marginally higher than IBC and the loss in the passive
components (Pc)halfofIBC.Thereby,theeciencyof
PSBC is contigious to IBC.
5. EXPERIMENTAL RESULTS
The prototype board of the converters and their exper-
imental setup is shown in Figure 7. The converters are
designedfor24Wpowerratingandtestedforaninput
voltage (Vin)of48V,withaswitchingfrequencyof
25 kHz. The values of inductor and capacitors used in
each prototype is given in Table 1.Thenumbersofcom-
ponentsusedineachprototypeandthecostofeach
prototype is listed in Table 3.
The converters are tested for both bright and dim condi-
tions. The waveforms for the proposed topology in bright

R. SRIMATHI AND S. HEMAMALINI: PERFORMANCE ANALYSIS OF SINGLE-STAGE LED BUCK DRIVER TOPOLOGIES 7
Figure 6: Flowchart for programmed LED lighting
condition are presented from Figure 8(a–f ). The voltage
and current of MOSFET switches, diode and inductor
are shown in Figure 8(a–c). The voltage across diode and
inductor is in Figure 8(d). The input and output voltage
and current with 50% duty ratio (bright condition) are in
Figure 8(e). The variation of output voltage and current
for the change in duty ratio step is given in Figure 8(f).
It is observed that, the output current is regulated for any
variationindutyratio.
The eciency of each driver for dierent duty ratio is
obtained experimentally and is shown in Figure 9.Itis
apparent that, the eciency of PSBC for dierent duty
ratio is not more than 1% as that of IBC. However, the cost
of PSBC is lesser than IBC by 69%. The eciency of CBC
is lesser and the cost is higher than PSBC. Therefore, for
lighting systems like buildings or any other applications,
there will be a considerable reduction in installation cost
and size of passive components with an increase in e-
ciency by using PSBC as LED driver. The output lumens
of LED light is measured for each driver using digital lux
meter (LX-101A). The results are in Table 4by testing the
PSBC with D=0.5 for bright and D=0.35 for dim con-
dition.ItisapparentfromTable4,thattheoutputlumens
of IBC is higher than PSBC for dim condition whereas it
almost similar for bright condition. Moreover, the output
lumens of CBC is low, when compared to other drivers.
Despite the fact that interleaved converters have high e-
ciency, high cost and less ripple, the PSBC converter is
suitable as a driver for low power lighting applications.
This is certainly because,
•PSBC is lesser in cost than IBC and CBC.
•There is no considerable dierence in eciency
between PSBC and IBC.
•ThesizeofthepassivecomponentsinPSBCislesser
than that of IBC.
6. LIGHTING IN POULTRY FARMS
The spectral sensitivity and visible spectrum of chick-
ens are not the same as in humans. Humans respond
to light around 400–750nm, whereas chickens can see
UV-A light of 315–400 nm in addition to 400–750 nm.
In addition to retinal light perception, poultry can sense
light through photoreceptors in the pineal gland and
hypothalamic gland situated in the dorsal surface of the
brain. The stimulation of the photoreceptors is impor-
tant in calming the ock, reducing injury and decreasing
time for production by stimulating ovulation through the
release of reproduction stimulating hormones [37]. In
India,thedierentlamptypesusedforindoorlightingin

8 R. SRIMATHI AND S. HEMAMALINI: PERFORMANCE ANALYSIS OF SINGLE-STAGE LED BUCK DRIVER TOPOLOGIES
Figure 7: Prototype boards of LED driver topologies and exper-
imental setup of PSBC. (a) CBC, (b) PSBC, (c) IBC, and (d) LED
load
poultry and livestock are incandescent lamp, uorescent
(T8, T5, T5HO), compact uorescent lamp, metal halide,
high pressure sodium and LED lights, etc. To have a good
economic demand response for consuming electricity in
poultry farms, energy ecient and cost eective LED
driverslikePSBCistobedesignedforlighting.Thisin
Table 3: Cost of each prototypes
No. of devices Cost of devices (Rs)
Components CBC IBC PSBC CBC IBC PSBC
MOSFET 1 2 2 19 38 38
Diode 1 2 1 32 64 32
Inductor 1 2 1 466 800 400
Capacitor 1 1 1 10 10 10
Microcontroller (Rs) 200 200 200
LED and sink (Rs) 50 50 50
Overheads (Rs) 200 200 200
Total cost (Rs) 977 1362 930
turn adds value to the Gross Domestic Product of poultry
sector which is nearly 4.4% of the Indian economy.
The recommended lighting guide for poultry production
farms as per standard ASAE EP344.3 (Lighting systems
for agricultural facilities) is given in Table 5. To validate,
that the proposed converter has a better payback period,
acasestudyisdoneinacommercialbreederfarmandit
is discussed in 6.1
6.1 Case Study in Bharamathi Poultry Farm
A commercial poultry farm named, Bharamathi located
inSouthernIndiaistakenforcasestudy.Ithasanexisting
unit with the dimensions 230 ×25 ×12”. The housing
of the farm is also one of the important criteria for the
growth and quality of the chicks. Usually east-west fac-
ing will be adopted in open house poultry farm for good
daylight. Unit I is a semi-housing with fenced windows in
the north-west direction so as to get good air circulation.
The total number of chickens that can be placed inside
this unit is 6666 and is calculated using (28).
Number of chickens =Length ∗Width
1.5ft (28)
Similarly the number of lights required for the farm is
calculated using the formula given in (29).
No. of Lights =foot candles
Initial lumens ∗Length ∗Width
Uitlization factor
(29)
The utilization factor of LED light is 0.92 whereas for
uorescent light it is 0.5.
6.2 Retrofit for Unit I in Bharamathi Farm
Retrot is a procedure of replacing the existing lighting
system with a new one. This is done for reducing the
electricity bill in buildings. The total number of uores-
cent lights existing in this poultry farm is 18. The farm
consumes nearly 520 kwh per billing period (two months

R. SRIMATHI AND S. HEMAMALINI: PERFORMANCE ANALYSIS OF SINGLE-STAGE LED BUCK DRIVER TOPOLOGIES 9
Figure 8: Hardware output of PSBC. (a) Voltage and current of MOSFET, (b) voltage and current of diode, (c) voltage and current of
inductor, (d) voltage across diode and inductor, (e) output waveforms, and (f) dynamic response over duty ratio
span) of which nearly 70% is consumed during the light-
ing. Unit I has 18 number of T5 xtures with 40 W uo-
rescent tube lights. They use Zig–Zag method of lighting
for dimming period. i.e.,thelightsareturnedONin
Zig–Zag fashion. The cost of a uorescent tube and the
electronic choke is Rs. 275/-, whereas LED light and LED
driver are Rs. 2700/-, respectively. As it is a retrot proce-
dure the number of LED lights remains same as uores-
cent lights. If the uorescent lamps of 40 W is replaced
by 24 W LED lights, the power consumption is reduced
to half [38]. In addition to the replacement of LED lights,
if the proposed driver is installed in LVDC system, the
installation cost and energy savings are calculated and
given in Table 6.
The power loss by each driver is calculated and is given in
Table 6.Theenergysavedbyeachdriverisestimatedfor
abillingperiodatatariofRs.4/-perunitandisgiven
in Table 6. The installation cost vs payback period for all
the drivers are shown in Figure 10.FromFigure10,the

10 R. SRIMATHI AND S. HEMAMALINI: PERFORMANCE ANALYSIS OF SINGLE-STAGE LED BUCK DRIVER TOPOLOGIES
Figure 9: Duty ratio versus efficiency
Table 4: Output lumens measured
Output Lumens (lm)
Driver Bright Dim
CBC 1510 710
PSBC 1783 934
IBC 1795 980
Table 5: Recommended lighting guide in poultry chicken
farms
Poultry type Age (weeks)
Minimum light
intensity (Lux)
Photo period (hours of
light per day)
Chicken broilers 0–0.4 20–30 24
0.4–4 5–10 20–12
4–8 5–10 20–24
Broiler breeders 0–3 30–50 18
4–20 10–30 9
20–64 30–50 15
Chicken layers 0–2 10–30 22–16
2–6 10–30 16–8
6–18 5–10 8–10
18–80 5–10 15
Table 6: Estimated installation cost and energy savings per
billing period
Components CBC PSBC IBC
Cost of driver (Rs) 977 930 1362
Total installationcost for 24W
(Rs)
18,486/– 17,640/– 24,516/–
Energy consumed by 40 W
fluorescent lamps,(D)
371.07 kWh
Energy consumed by 24W LED
lights, (E)
185.54 kWh
Power loss/driver in W 1.6 1.28 1.42
Energy loss in 18 drivers in
KWh,(F)
28.8 25.56 23.04
Total energy consumed in
KWh,(E+F)
214.34 211.11 208.58
Net energy saved in KWh, (D-G) 156.73 162.49 159.97
Net amount saved in Rs. 626.9 649.96 639.88
PSBC driver appears to have better payback period than
other drivers. The LED and the driver continue to serve
for nearly ten years even after the payback period. This
will have a return of Rs. 19,473/- for the farm. Therefore,
Figure 10: Installation cost versus payback period
Figure 11: Lighting design. (a) Fluorescent lighting and (b) LED
lighting
for a developing country like India, it is suggested to use
PSBC driver when compared to other drivers.
ThelayoutofunitIwithLEDlightisdoneusingAUTO-
CAD software. Later, the lights are placed in the layout
using DIAlux software in the three dimensional CAD
drawing so as to achieve uniform lux level throughout
thefarm.Thedesignlayoutforlightingwithuores-
cent lights and LED lights for bright condition alone is
illustrated in Figure 11.FromFigure11,itcouldbevisu-
alized that use of LED lights enhances the brightness level
when compared to uorescent lights. Moreover, the use of

R. SRIMATHI AND S. HEMAMALINI: PERFORMANCE ANALYSIS OF SINGLE-STAGE LED BUCK DRIVER TOPOLOGIES 11
PSBC driver in the farm will have a good payback period
and economic demand response in electricity usage.
7. CONCLUSION
Single-stage LED buck drivers is designed and imple-
mented in this paper. The proposed driver is mathemat-
ically modelled and analysed in terms of eciency, cost,
andsizeofthepassivecomponents.Thecontrollerper-
formance is also analysed and compared. Further, a case
studyisdoneforapoultryfarmandtheresultsofthe
proposed driver is validated in terms of installation cost,
payback period, and energy savings. The energy saved
through retrot procedure is estimated and presented. It
is also found that the PSBC driver gives better perfor-
mance than all other drivers in terms of energy savings.
ThenetprotforthefarmwhenreplacedwithLED
lightsandPSBCdriverisalsopresented.Therefore,PSBC
driver is the best alternative for LED lighting systems
in buildings or any applications and is suggested for the
LVDC systems.
ACKNOWLEDGMENTS
The rst author gratefully acknowledges the “VIT,” Chennai
and the management of “Bharamathi farm” for the support
received because of which the work reported in the paper was
possible.
DISCLOSURE STATEMENT
No potential conict of interest was reported by the authors.
ORCID
R. Srimathi http://orcid.org/0000-0002-3956-9080
S. Hemamalini http://orcid.org/0000-0001-8128-6407
REFERENCES
1. I. Rozenboim, B. Robinzon, and A. Rosenstrauch, “Eect
of light source and regimen on growing broilers,” Br.
Poult. Sci., Vol. 40, no. 4, pp. 452–7, 1999.doi:10.1080/
00071669987197
2. N. Prescott and C. Wathes, “Spectral sensitivity of the
domestic fowl (gallus g. domesticus),” Br. Poult. Sci.,Vol.
40, no. 3, pp. 332–9, 1999.doi:10.1080/00071669987412
3. K. Liu, H. Xin, and L. Chai, “Choice between uores-
cent and poultry-specic led lights by pullets and laying
hens,” Trans. ASABE, Vol. 60, no. 6, pp. 2185–2195, 2017.
doi:10.13031/trans.12402
4. P.M.Pattison,M.Hansen,andJ.Y.Tsao,“LEDlightinge-
cacy: status and directions”, Comptes Rendus Physique,Vol.
19, no. 3, pp. 134–145, 2018.doi:10.1016/j.crhy.2017.10.013
5. “Energy Statistics 2017.” Available: http://www.indiaenvir-
onmentportal.org.in/les/le/Energy_Statistics_2017.pdf,
2017.
6. R.Srimathi,S.Sitoke,andS.Hemamalini,“Higheciency
buck led driver using sic,” Energy Procedia, Vol. 117, pp.
224–235, 2017.doi:10.1016/j.egypro.2017.05.126
7. P. Athalye, M. Harris, and G. Negley, “A two-stage led
driver for high-performance high-voltage led xtures,”
in Applied Power Electronics Conference and Exposition
(APEC), pp. 2385–91, IEEE, 2012.
8. E. S. Lee, B. H. Choi, D. T. Nguyen, B. G. Choi,
and C. T. Rim, “Static regulated multistage semiac-
tive led drivers for high-eciency applications,” IEEE
Trans. Pow er E le ctron., Vol. 31, no. 9, pp. 6543–52, 2016.
doi:10.1109/TPEL.2015.2503564
9. H. Khalilian, H. Farzanehfard, E. Adib and M. Esteki,
“Analysis of a new single-stage soft-switching power-
factor-correction LED driver with low DC-Bus voltage,”
IEEE Trans. Indust. Electron., Vol. 65, no. 5, pp. 3858–3865.
doi:10.1109/TIE.2017.2764841
10. W. Chen and S. R. Hui, “Elimination of an electrolytic
capacitor in ac/dc light-emitting diode (led) driver with
highinputpowerfactorandconstantoutputcurrent,”IEEE
Trans. Pow er E le ctron., Vol. 27, no. 3, pp. 1598–1607, 2012.
doi:10.1109/TPEL.2010.2103959
11. H-Y. Park, B-J. Seo, K-S. Park, K-S. Kang, and E-
C. Nho, “Electrolytic capacitor-less high-brightness LED
driving AC/DC converter for LED performance degrada-
tion reduction,” Electron. Lett., Vol. 54, no. 10, pp. 648–649,
2018.doi:10.1049/el.2018.0745
12. C. Shin, et al., “Sine-reference band (SRB)-controlled aver-
agecurrenttechniqueforphase-cutdimmableAC-DC
buck LED lighting driver without electrolytic capacitor,”
IEEE Trans. Power Electron., Vol. 33, no. 8, pp. 6994–7009,
2018.doi:10.1109/TPEL.2017.2758167
13. Y. N. Yi Chen and Q. Kong, “A loss-adaptive self
oscillating buck converter for led driving,” IEEE Trans.
Power Electron., Vol. 27, no. 10, pp. 4321–8, 2012.
doi:10.1109/TPEL.2012.2190755
14. T.Hakala,T.Lähdeaho,andP.Järventausta,“Low-voltage
dc distributionutilization potential in a large distribution
network company,” IEEE Trans. Power Delivery, Vol. 30, no.
4, pp. 1694–701, 2015.doi:10.1109/TPWRD.2015.2398199
15. X.Wu,C.Hu,J.Zhang,andZ.Qian,“Analysisanddesign
considerations of llcc resonant multioutput dc/dc led
driver with charge balancing and exchanging of secondary
series resonant capacitors,” IEEE Trans. Power Electron.,
Vol. 30, no. 2, pp. 780–9, 2015.doi:10.1109/TPEL.2014.
2309605
16. C.-Y. Hsieh and K.-H. Chen, “Boost dc-dc converter
with fast reference tracking (frt) and charge-recycling (cr)

12 R. SRIMATHI AND S. HEMAMALINI: PERFORMANCE ANALYSIS OF SINGLE-STAGE LED BUCK DRIVER TOPOLOGIES
techniques for high-eciency and low-cost led driver,”
IEEE. J. Solid-State. Circuits., Vol. 44, no. 9, pp. 2568–80,
2009.doi:10.1109/JSSC.2009.2024051
17. Y.HuandM.M.Jovanovic,“Leddriverwithself-adaptive
drive voltage,” IEEE Trans. Power Electron.,Vol.23,no.6,
pp. 3116–25, 2008.doi:10.1109/TPEL.2008.2004558
18. X. Wu, Z. Wang, and J. Zhang, “Design considerations
for dual-output quasi-resonant yback led driver with
current-sharing transformer,” IEEE Trans. Power Electron.,
Vol. 28, no. 10, pp. 4820–30, 2013.doi:10.1109/TPEL.2012.
2234480
19. S. Choi and T. Kim, “Symmetric current-balancing circuit
for led backlight with dimming,” IEEE Trans. Industr. Elec-
tron., Vol. 59, no. 4, pp. 1698–707, 2012.doi:10.1109/TIE.
2011.2138112
20. P.-J. Liu and Y.-C. Hsu, “Boost converter with adap-
tive reference tracking control for dimmable white LED
drivers,” Microelectronics. J., Vol. 46, no. 6, pp. 513–8, 2015.
doi:10.1016/j.mejo.2015.03.022
21. H. Han, F. Zhang, and M. Liu, “PWM dimming method
for capacitor clamped current-sharing circuit in LED back-
light system,” IEEE J. Emerg. Select. Topics Power Electron.,
Vol. 6, no. 3, pp. 1190–1197, 2018.doi:10.1109/JESTPE.
2018.2825640
22. C. Yao, “Power supply transient reduction method for mul-
tiple LED channel systems,” US Patent 9 967 932, May 8,
2018.
23. W. Li, “Backlighting dimming circuit and liquid crys-
tal display,” US Patent App. 15/032,052, March 29,
2018.
24. J. Mazzochette and G. E. Blonder, “Led array package
with internal feedback and control,” US Patent 7 252 408,
August 7, 2007.
25. T. B. G. Vangalapudi and D. Kastha, “Quasi-parallel volt-
age regulator topology for powering laptop processors,”
IEEE Trans. Power Electron., Vol. 32, no. 10, pp. 7805, 2017.
doi:10.1109/TPEL.2016.2639581
26. R. G. Retegui, M. Benedetti, M. Funes, P. Antoszczuk, and
D. Carrica, “Current control for high-dynamic high-power
multiphase buck converters,” IEEE Trans. Power Electron.,
Vol. 27, no. 2, pp. 614–8, 2012.doi:10.1109/TPEL.2011.
2158658
27. P.Horsky,J-P.Eggermont,J.Plojhar,M.Musil,andP.A.
Decloedt, “Apparatus, systems and methods for average
current control in a buck DC/DC LED driver,” US Patent
9 887 614, February 6, 2018.
28. J. Rodríguez, D. G. Lamar, D. G. Aller, P. F. Miaja, and J.
Sebastián, “Ecient visible light communication transmit-
ters based on switching-mode dc-dc converters,” Sensors,
Vol. 18, no. 4, pp. 1127, 2018.doi:10.3390/s18041127
29. J.Garcia,A.J.Calleja,D.G.Corominas,E.L.Vaquero,
and L. Campa, “Interleaved buck converter for fast
pwm dimming of high-brightness leds,” IEEE Trans.
Power Electron., Vol. 26, no. 9, pp. 2627–36, 2011.
doi:10.1109/TPEL.2011.2121922
30. J.-P.Lee,H.Cha,D.Shin,K.-J.Lee,D.-W.Yoo,andJ.-Y.Yoo,
“Analysis and design of coupled inductors for two-phase
interleaved dc-dc converters,” J. Power Electron., Vol. 13,
no. 3, pp. 339–48, 2013.doi:10.6113/JPE.2013.13.3.339
31. R. Middlebrook and S. Cuk, “A general unied approach
to modelling switching-converter power stages,” in Power
Electronics Specialists Conference, 1976 IEEE, pp. 18–34,
IEEE, 1976.
32. K. Smedley and S. Cuk, “Switching ow-graph nonlinear
modeling technique,” IEEE Trans. Power Electron.,Vol.9,
no. 4, pp. 405–13, 1994.doi:10.1109/TPEL.63
33. V. Vorpérian, “Simplied analysis of pwm converters
using model of pwm switch. ii. discontinuous conduction
mode,” IEEE. Trans. Aerosp. Electron. Syst.,Vol.26,no.3,
pp. 497–505, 1990.doi:10.1109/7.106127
34. F. Luo and H. Ye, “Energy factor and mathematical
modelling for power dc/dc converters,” IEE Proc. Elec-
tric Power Appl., Vol. 152, no. 2, pp. 191–8, 2005.
doi:10.1049/ip-epa:20055119
35. J. Roh, “Analogue-to-digital interface technique for digital
controllers in dc-dc converters,” Electron. Lett., Vol. 41, no.
18, pp. 1034–6, 2005.doi:10.1049/el:20051452
36. F. Krismer and J. W. Kolar, “Accurate power loss model
derivation of a high-current dual active bridge converter
foranautomotiveapplication,”IEEE Trans. Industr. Elec-
tron., Vol. 57, no. 3, pp. 881–91, 2010.doi:10.1109/TIE.2009.
2025284
37. L. Tianhu, et al., “Layer illumination management technol-
ogy based on led,” Energy Procedia, Vol. 16, pp. 477–82,
2012.doi:10.1016/j.egypro.2012.01.077
38. T. Hong, et al., “Commercial building energy saver: an
energy retrot analysis toolkit,” Appl. Energy, Vol. 159, pp.
298–309, 2015.doi:10.1016/j.apenergy.2015.09.002

R. SRIMATHI AND S. HEMAMALINI: PERFORMANCE ANALYSIS OF SINGLE-STAGE LED BUCK DRIVER TOPOLOGIES 13
Authors
R. Srimathi received the B.E degree in
Electrical and Electronics Engineering
from the Bharathiar University, Coimbat-
ore, India, and M.Tech degree in Power
Electronics and Drives from SASTRA
University, Thanjavur, India. She is cur-
rentlypursuingPh.DandalsoaSenior
Lecturer with the Department of Electrical
and Electronic Engineering, VIT, Chennai, India. Her research
interests include smart LED lighting systems, Energy savings
in buildings, Power converters for DC microgrids, Mathemat-
ical modelling of converters, Control techniques for converter.
R.Srimathi is a member of the IEEE Power Electronics Society.
Email: srimathi.r@vit.ac.in
S. Hemamalini receivedtheB.E.degree
in electrical and electronics engineering
from the Thiagarajar College of Engineer-
ing, Madurai, India, and both M.Tech. and
Ph.D. degree in power systems from the
National Institute of Technology, Tiruchi-
rappalli, India. She has teaching and
research experience of about 20 years. She
is currently a Professor with the School of Electrical Engi-
neering, VIT, Chennai, India. Her current research interests
include power system optimization, renewable energy, micro-
grids, power electronics applications in power systems, reli-
ability and protection in microgrids, and electric vehicles.
Dr Hemamalini is a member of the Power and Energy Society
and the IEEE Power Electronics Society, and a Lifetime Mem-
ber of the Indian Society for Technical Education.
Corresponding author. Email: hemamalini.s@vit.ac.in