A Solar Based SEPIC Converter For Street Lighting ... - IEEE Xplore

29 downloads 53863 Views 2MB Size Report
clean sustainable energy source. Photovoltaic solar energy systems require DC-DC converter in order to regulate and control the varying output of the solar ...
2016 International Conference on Computation of Power,

Energy Information and Communication (ICCPEIC)

A Solar Based SEPIC Converter For Street Lighting Application G.Arunkumar, D.Elangovan

Jagadish Kumar Patra,

Cynthia James, Saumya vats

Assistant Professor

TaniaH.M.

UG Student

School Of Electrical

PG Student

School Of Electrical

Engineering

School Of Electrical

Engineering

VIT University

Engineering

VIT University

Veilore, India

VIT University

Vellore, India

[email protected]

Vellore, India

Abstract�There has been an increase in demand for clean and sustainable energy sources, and solar energy is currently

paper will focus on using solar energy for a large electricity requirement such as street lamps.

considered to be one of the most valuable and abundant yet low-maintenance

clean

sustainable

energy

source.

Photovoltaic solar energy systems require DC-DC converter in order to regulate and control the varying output of the solar panel. The single ended Primary inductance Converter topology performs the operation of a buck-boost converter but with no voltage polarity reversal. This paper suggests a converter design that will ensure high performance and cost efficiency while powering up an LED street lamp.

The

converter has been simulated in PSIM and the hardware was done by choosing the design values appropriately.A voltage

While dealing with application of renewable energy sources, the electrical equipment designs require converters. The energy is harnessed from the source, and then it goes through the conversion stage, which is required to deal with the fluctuating and lower output voltage characteristics of renewable energy. While many converter topologies are available today, the SEPIC topology is integrated into the design of solar powered street lamps due to specific advantages. [1-4]

input value of 24volts and output value of 72 volts are assigned in correspondence with the streetlamp ratings. This design

aims

to

have

lower

losses

for

higher

switching

frequencies, and maximize the added advantages of the proposed converter, such as low ripple, high efficiency and low electrical stress on the components.

Keywords-solar; SEPIC; Buck-Boost; LED Lamp.

I.

INTRODUCTION

The world's excessive dependence on fossil fuels and other non-renewable energy sources have lead to their depletion. Hence, today we look up to renewable energy sources, which are reliable and plentiful and will be easy to harness once the right kind of technology and infrastructure is made available. Solar energy, among them, is the most readily available one all around the world. According to trends seen in USA and Japan, in the next few years, it is predicted that millions of households all around the world will be using solar energy. In India, the Indian Renewable Energy Development Agency and the Ministry of Non-Conventional Energy Sources are formulating a program to have solar energy in more than a million households within the next few years. In such a country as this with plentiful sunshine all throughout the year, especially in regions such as Thar, it is possible to harness solar energy for a wide range of applications. This

There are five main DC-DC converter topologies available today. Buck converter can reduce input voltage, Boost can increase voltage, while Buck-Boost, Cuk and SEPIC converters can both reduce and increase voltage. However, the Single-Ended Primary-Inductor Converter (SEPIC) is the only DC/DC converter that can essentially function like a Buck-Boost converter but with the added advantage of producing a non-inverted output. It can be argued that Buck-Boost converters are cheaper as they only require a single inductor and capacitor, but these converters also suffer from high input current ripple. [58]Current ripple can create harmonics, which in many cases will necessitate the use of large capacitors or an LC filter. This makes buck-boost inefficient and costly. Cuk converter can compensate for the shortcomings of Buck-boost converters, and simultaneously can also produce non-inverted output voltage. However, his converter causes large amounts of electrical stress on its components, resulting in device failure or overheating. SEPIC converters are able to solve all these problems. Furthermore, in SEPIC, the coupling capacitor energy from input to output enables the device to handle short circuits in a more controlled manner when compared to

978-1-5090-0901-5/16/$31.00 m016 IEEE 482

G.Arunkumar et at: A Solar Based SEPIC Converter For Street Lighting Application

the traditional converter topologies. The SEPIC design uses minimal active components and 'clamped' switching waveforms that produce reduced noise from high frequency switching operations, hence dealing with issues causes my electromagnetic interferences. II.

(2) Cl

DC

BLOCK DIAGRAM

RL

C2

Fig.3. ON State. When switch S is turned onas shown in Fig 3, VCI is approximately equal to Yin, and VL2 is approximately equal to -Vin• Current III increases while IL2 decreases proportionally. Inductor Ll is charged using the input source, while L2 is charged using energy from C1. Cl

Fig.I. System Block Diagram. The overall setup is shown in Fig.l wherein, the input is supplied by the Solar simulator which feeds the SEPIC converter .The converter supplied the lighting loads at nv by appropriate power conversion (Boost operation).The switching pulse for the converter is generated by dSPACE 1104 which can be interfaced to MATLAB R2013. III.

C2

1l21'

DC

L2 •

RL

C2

Fig.4. OFF State. When S is turned offas shown in Fig 4, that branch of the circuit is open-circuited. Then, the current through C1becomes the same as that through L1. The current through L2 continues to flow in the reverse direction. This negative current through L2 then adds up with ILland increases the current delivered to the load. Therefore, Ll is charged by C1 during this off state and power is delivered to the load from both L2 and Ll.

CIRCUIT DIAGRAM AND MODES OF OPERATION

D

DC

D

RL

During the Discontinuous mode of conduction the current through the inductor Ll is able to fall to zero. Fig.2. SEPIC Topology. Circuit diagram of the proposed converter is shown in Fig 2.There are two modes of conduction, being the continuous mode and the discontinuous mode.

IV.

MATHEMATICAL DESIGN

Duty Cycle of the converter is given by,

During the continuous-conduction mode, the current through the inductor Ll never falls to zero. During the steady-state operation, the average voltage that falls cross capacitor C1 equals the input voltage (Vin), as the C1 blocks DC current. Now, inductor L2 is the only source of DC load current. Hence, inductor L2 is independent of input voltage as the average current through L2 is the same as the average load current. Hence, we formulate the equation; (1)

D=

VOlli �n + VOlli

(3)

Inductor Selection is done by, V Iripple -Ialit x�x40% -

IOllt

=

P

Valli

--

�n

(4)

(5)

L1 = L2 = L = �n XD Since V CI equals Vin, VL1=-VL2, and since the voltages are Iripple X Fs of the same magnitude, the ripple currents from the two inductors are also of the same magnitude. The average current is now assumed to be 978-1-5090-0901-5/16/$31.00 m016 IEEE

(6)

483

2016 International Conference on Computation of Power, VOlit ILI(Peok) - Iout x -- x VIn

IL2(Peok)

=

(1

+

40% -2

)

(7)

(1 � ) �

lout X

+

4 %

Energy Information and Communication (ICCPEIC)

The steady state waveforms of Input voltage , input current, output voltage and output current are shown in Fig.S (software output) and Fig.6 (Hardware output) .

(8) 1

200VI

2

5 0AI

3 500VI

4

2 0Al

8 256$

Coupling Capacitor Selection is done by, 1C (rm ) - 1alit x , s

Vm"

(9)

�n

"-

Ialit xD

Z

(10) C XF s s Output Capacitor Selection is done by, ,

=

=

1alit x



J

242

(11)

V,,", VIn

V.

ItN

4.14A

VO' 70V

Iou / x D :..:::. Cout> --....:'---Vnpple X 0.5 x F s

1Cou,(rm ) s

Stop

2V

t

Peak-to-Peak Ripple Voltage on Cs is given by,

L"!.vc

2000:1 V'N=

(12)

RESULTS

Vinput

\...

'!.

1.80A

10

Fig.7. Hardware result of Transient state output. Fig.7 shows the transient behavior of the converter. When input of 22V is given to the converter, the response is faster and the converter reaches steady state within few milliseconds which can be observed from the figure.

��: t:l:::::::;:::::::�:::::::l:::::::;::::::L:::::�:::::: ::::::: ::::1

\hwitch

I input

�-- ----------------n --- ------0 -- -- -- ---0-- -----[J -------------------- ----------- --- ----------- -------- ----------------- ---- ------------------- -------

00