Transcript Battery Charge Regulator for a photovoltaic power system using

*Supervised by :
Prof. Marwan Mahmoud
*Prepared By :
Esra’ Khader & Mohaia Eshtawe
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Project Goals :
To construct a regulated DC power
supply 12 V / 3A source . the power
supply converts the (220-230) V AC
into(12 V – 3A) DC output .
 To simulate PV module output (adjustable
current & voltage) in the laboratory .
 Establishment of a possibility Useful for
testing of charge regulator being used in
PV system .

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Introduction

For electronic circuits made up of transistors
and/or ICs, this power source must be a DC
voltage of a specific value.
 A regulated power supply is one that controls
the output voltage or current to a specific
value; the controlled value is held nearly
constant despite variations in either load
current or the voltage supplied by the power
supply's energy source.
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Circuitry:
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We have two parts in our
circuit: (first part)
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Second part:
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Block Diagram
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Transformer
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Transformer:
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The out put of the first
secondary part: (24 v)
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The out put of the second
secondary part: (22 v)
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Transformer
 how we select the transformer ?
Transformer specification
N1 902/Ø 0,4mm
N2 70/Ø 1.2mm
N3 58/Ø 0.224mm
N1 V1
N2
70
  V2 
 V1 
 220  17v
N 2 V2
N1
902
V2 M  24v
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Transformer
N 3 V3
N3
58

 V3  V1 

 220  14v
N1 V1
N1 902
V3 M  20v
 we add protection to the circuit ,we use fuses one at
the input of the circuit before the transformer
400mA , and another one after the rectifier 4A they
will break if current increases for any reasons and
protect our circuit.
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400mA fuse was added before
the transformer:
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4A fuse was added after the
rectifier :
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Rectifier:
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 The rectifier converts the AC sine wave into a
pulsating DC wave.
 We use Full-wave rectification because it
converts both polarities of the input
waveform to DC (direct current), and it is
more efficient.
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Rectifier
Vd 1 
2Vm 2
Vd 2 
2V3




2  24

2  20

 15v
Average
voltage
 12.7v
Average
voltage
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The output of the rectifier is:
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Ripple frequency ( fr):
1
1
fr 

 100 Hz
Tr
10 ms
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Why we want to remove the
ripple ?
 The presence of ripple can reduce the resolution of
electronic test and measurement instruments. On an
oscilloscope it will manifest itself as a visible pattern
on screen.
 Within digital circuits, it reduces the threshold, as
does any form of supply rail noise, at which logic
circuits give incorrect outputs and data is corrupted.
 High amplitude ripple currents reduce the life of
electrolytic capacitors.
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Ripple:
 The varying DC output is suitable for lamps,
heaters and standard motors.
 It is not suitable for electronic circuits unless
they include filter.
 Our filter is very large capacitor(C=1mF) called
smoothing capacitor.
 We estimate the value of the capacitor according
to the following equation:
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du
I
I
I
  u   dt  t
dt C
C
C
 Where :
I constant value
:
C
t: discharge time of the capacitor
u: ripple voltage
 The smooth DC output has a small ripple. It is
suitable for most electronic circuits.
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Ripple calculation in our circuit:
I  t 200mA  8ms
C

u
2v
From table of standard value we use C=1mF
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 Capacitor
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 A filter is used to remove the pulsations and create a
constant output.
 Smoothing is performed by filter (1mF capacitor)
connected across the DC supply to act as a reservoir,
supplying current to the output when the varying DC
voltage from the rectifier is falling. The capacitor
charges quickly near the peak of the varying DC, and
then discharges as it supplies current to the output.
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Regulator:
 The regulator fixes the output voltage to the
desired level then maintains that value despite
any output or input variations.
 Regulated circuit we use simple Zener diode
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Regulator:
 The regulated DC output is very smooth with no ripple.
It is suitable for all electronic circuits.
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The regulated DC output is very smooth with no
ripple. It is suitable for all electronic circuits.
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Inter Mediate Stages
 Operational amplifier:
Used with this special
Connection for distortion
Cancellation
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Transistors:
used for amplifications
And switches purposes.
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 The final output of our circuit is
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 We measure the output
 Voltage: The maximum value we could reach is about
11v (it was changing between 1.5 v – 11 v)
 Current: The maximum value we could reach is about
600 mA (it was changing between micro amperes –
600 mA)
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Conclusion:
 After all work we did on our project we have learned so many things :
 We always see A DC power supplies in laboratories and a DC




charger for example for mobiles, laptops, cameras and so many
things…
It is the first time we learnt about its major stages.
it is the first time that we deal with transformer in these details .
we have studied the rectifiers in Power Electronics course but it is
the first time we see the output at the oslliscope by our work.
we notice what useful we get from using a fuses for protection.
It is the first time we deal with many IC’s we studied in many courses
like(power transistors ,operational amplifier ,zener diodes ,etc…)
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Mistakes we did:
 the first time we switch on the transformer it is
secondary output wires touch each other and make
short circuit but fortunate the fuse break and protect
the transformer.
 we have faced so many welding problems.
 we use a npn transistor instead of pnp and this force us
to reconnect our project.
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Problems we face :
 we couldn’t find some of IC’s so we use it’s
complementary
 lack of equipment and instruments in the workshop
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Future stages
 Micro-controller
If a design pic micro controller added that will work as
indicator for the situation of the DC power supply
(KWh , Output current, output voltage especially by
charging a battery)
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Finally:
QuEsTiOnS
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