YEDITEPE UNIVERSITY
ENGINEERING & ARCHITECTURE FACULTY
INDUSTRIAL ELECTRONICS LABORATORY
EE 432 – INDUSTRIAL ELECTRONICS
Deniz
Yildirim
EXPERIMENT 1
SINGLE-PHASE FULL-WAVE RECTIFIER AND LINEAR
REGULATOR
Introduction:
In this experiment groups will perform the construction of a basic AC-DC converter
(rectifier) circuit. This is a simple example of a regulated DC power supply. You will see an
application of one of the basic switching elements (diode) studied in the course. Employing a
basic regulator integrated circuit (IC), the output voltage is kept constant at value of 15
VDC, 1 A regardless of loading conditions and input voltage variations.
Equipments:
726 88
537 34
735 01
735 095
578 37
7815
100n, 20V
1kΩ, 1/4W
LED
Metra Hit 25S
Fluke 66
DW-6060
Table 1. List of Equipments
AC/DC Stabilizer, 220V Transformer
Variable Load Resistor (0-100Ω, 1.8A)
Bridge rectifier
Capacitor, 1000µF
Capacitor, 10µF 35V
15V Linear Regulator
Capacitors
Resistor
Light Emitting Diode
Heatsink for TO-220 package
Breadboard
Multi-Meter (x3)
Infrared Thermometer
AC Power Wattmeter
Note: It may be useful to have copies of datasheets of semiconductor components given in Table 1.
General Information:
Power is distributed to consumers through AC distribution lines. Almost all electronic
equipment like computers, TV, hi-fi equipment and instruments are powered by DC power
sources, either by batteries or DC power supplies obtained from an AC source. Most
electronic equipment requires not only DC voltage but voltage that is also filtered and well
regulated. Regulated AC-to-DC converters have a wide range of use as power supplies in
many industrial and consumer applications.
EE432 Industrial Electronics, Fall 2011
Experiment 1, page 1/7
Last updated October 10, 2011 7:10 AM by D. Yildirim
Digitally signed by Deniz
Yildirim
DN: CN = Deniz Yildirim, C =
TR, O = Istanbul Technical
University, OU = Electrical
Engineering
Reason: I am the author of
this document
Date: 2011.10.10 07:12:13
+03'00'
A power supply converting AC line voltage to DC power is expected to perform the
following functions at high efficiency with a very low cost:
•
•
•
•
•
•
Voltage Transformation: Reduce the incoming AC utility voltage to lower AC
voltage values.
Rectification: Converting the reduced AC line voltage to pulsating DC voltage.
Filter: Smooth the ripple of the rectified voltage.
Regulation: Control of the output voltage to a constant value regardless of variations
in AC line, load and temperature changes.
Isolation: Electrical separation (isolation) of output voltage from the input source.
Protection: Prevent damaging voltage surges from reaching the output; provide safe
shut down during a brown-out or high load.
An ideal power supply would be characterized by supplying a smooth and constant output
voltage regardless of variations in line voltage, load current or ambient temperature at 100%
conversion efficiency.
There are two types of AC-DC converters; Linear Converters and Switch-Mode Converters.
In this experiment, groups will perform a single-phase full-wave rectifier with a linear
regulator. Figure 1 shows a typical schematic for this circuit.
A transformer, a bridge rectifier, low and high frequency filters, a Blue LED, and a linear
regulator are depicted. The transformer reduces the input AC line voltage to the desired
lower voltage level. Diodes D1 to D4 form a bridge rectifier where this circuit topology is
called an uncontrolled rectifier. Diodes D1 and D4 work together to rectify the positive half
cycle of the sinusoidal waveform while diodes D2 and D3 rectify the negative half cycles.
Capacitor Cf filters the 100 Hz ripple component of the rectified voltage. Even though the
voltage has been rectified and regulated, there may be some high frequency spikes on the DC
output. A high frequency ceramic or mica capacitor may be connected in parallel with Cf in
order to filter these high frequency spikes (harmonics). The linear voltage regulator behaves
as a variable resistance between the
regulator
78XX
+
Iout
24
vs
Cf
12
C1
Vdc
6
A
+
C2
Rled
V
V
Vout
Rload
0
Deniz Yildirim
Feb 21, 2011
e1r.eps
726 88
LED
735 01
735 095
Pdc
Pout
Figure 1. Single-Phase Full-Wave Rectifier with Linear Regulator
input and the output as it provides the precise and well regulated output voltage. One of the
limitations to the efficiency of this circuit is due to the fact that the linear device must drop
the difference in voltage between the input and output. While these supplies have many
desirable characteristic, such as simplicity, low output ripple, excellent line and load
EE432 Industrial Electronics, Fall 2011
Experiment 1, page 2/7
Last updated October 10, 2011 7:10 AM by D. Yildirim
regulation, fast response time to load or line changes and EMI, they suffer from low
efficiency. A Blue Light Emitting Diode (LED) at the output of bridge rectifier is used as an
indicator. Resistor Rled is used to limit the current going through the LED which is typically
20mA. You should calculate the value of this resistor considering the output voltage of the
bridge rectifier and forward voltage drop of LED.
Procedure of Experiment:
Before coming to the laboratory students are advised to make a small research about singlephase full-wave rectifiers with linear regulators as a preliminary work. Students can find the
necessary information from either text books or from data sheets of linear regulator.
Please note that the power supply that you are testing will have a constant DC output voltage
at 15V and 1A rated current values from a utility input voltage of 220V, 50Hz AC voltage.
Note: When capturing oscilloscope screen and include in your report, you have to specify
the time base (… ms/div) and scale of voltages (…V/div).
1. Voltage Transformation and Rectification
Circuit Set-up:
Assemble the circuit shown in Figure 2. Adjust the load resistor such that rated current
flows through load resistor.
A
Iout
24
vs
12
+
+Vsec
6
Vdc
-
V
-
Rload
0
Deniz Yildirim
Oct 12, 2010
e1rbr.eps
726 88
735 01
Figure 2. Voltage Transformation and Rectifier
•
Using a multimeter measure the input voltage Vs, the transformer voltage Vsec and
output voltage Vdc. Write down the measured values to the Table 3 given below.
•
With the help of an oscilloscope obtain the time waveforms (two complete cycles of
input voltage frequency) of Vsec and Vdc using the save screen feature of oscilloscope.
Determien peak-to-peak values and fill in Table 3.
2. Filtering the 100 Hz AC Ripple Component
Circuit Set-up:
Assemble the circuit shown in Figure 3. Adjust the load resistor such that rated current
flows through load resistor.
EE432 Industrial Electronics, Fall 2011
Experiment 1, page 3/7
Last updated October 10, 2011 7:10 AM by D. Yildirim
•
By adding a filter capacitor Cf you shall reduce the voltage ripple as much as
possible.
A
vs
+Vsec
12
6
Cf
Vdc
V
-
Rload
-
0
Deniz Yildirim
Feb 21, 2011
e1rbrc.eps
726 88
Iout
+
24
735 01
735 095
Figure 3. Filtering the 100 Hz Component
•
Try three different capacitor values (10µF, 500µF and 1000µF) and observe their
effects on the voltage ripple. Comment on your observations in your report. Include
oscilloscope images supply voltage and output voltage.
•
Draw the voltage Vdc with the help of an oscilloscope on the scope sheet for two
different capacitor values. Measure the output voltage ripple and write values in
Table 4..
•
Measure and write down the voltage Vdc and Vdc,ripple with a multimeter and write
values in Table 4.
Please note that output voltage is DC with small AC ripple riding on it. Select proper type on
the multimeter for ripple measurement (select VDC for DC, and select VAC for ripple).
3. Visual Indicator
Circuit Set-up:
Assemble the circuit shown in Figure 4. Adjust the load resistor such that rated current
flows through load resistor.
•
Calculate the value of resistor Rled to limit the current passing through the led to 20
mA. Write down the value in Table 4. Show calculations in your report.
A
Iout
24
vs
12
Vsec
Cf
+
6
+
Rled
Vdc
V
-
Rload
0
Deniz Yildirim
Feb 21, 2011
e1rbrcled.eps
726 88
LED
735 01
735 095
Figure 4. Visual Indicator
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Experiment 1, page 4/7
Last updated October 10, 2011 7:10 AM by D. Yildirim
4. Placement of the Linear Regulator and Its Effects
Circuit Set-up:
Set the circuit shown in Figure 5.
DW6060
source
load
AC Wattmeter
Pac
regulator
78XX
+
Iout
24
vs
Cf
12
C1
Vdc
6
A
+
C2
Rled
V
V
Vout
Rload
0
Deniz Yildirim
Feb 21, 2011
e1rp.eps
LED
-
726 88
735 01
735 095
Pac
Pdc
Pout
Figure 5. Single-Phase Full-Wave Rectifier with Linear Regulator and Resistive Load
• Connect the linear regulator IC and the variable resistor to the circuit.
• Adjust the load resistor such that rated current flows through load resistor. It may be
necessary to place a heatsink on the regulator as it will get very hot.
• To measure the overall efficiency of the regulator, do the following steps:
a) By setting the variable resistor to 10 different values, measure: Iout, Vout, Vdc, Pac and
case temperature and fill in the values in Table 6 where Pac is the real power input
from the utility. Case temperature measurements should be performed using
infrared thermometer, please direct laser guided sighting system (red dot) onto the
plastic case of the regulator as illustrated in Figure 6.
NOTE: Please be careful not to short the circuit the output by adjusting
the variable resistor resistance to 0 Ω.
b) Calculate the regulator, rectifier bridge and rectifier efficiencies from the measured
values:
Pout
P
P
ηbridge = dc
ηrec = out
Pdc
Pac
Pac
where Pout, Pdc, and Pac are the DC output, bridge output, and input powers,
ηreg =
respectively.
• Plot all of the above measurements as a function of Iout (plots are required for
report).
Measure the no–load and rated load output voltages and fill in the values in Table 5.
Calculate Voltage Regulation of your rectifier
EE432 Industrial Electronics, Fall 2011
Experiment 1, page 5/7
Last updated October 10, 2011 7:10 AM by D. Yildirim
c) Obtain the time waveforms of Vdc and Vout at full output power (i.e., 1A) and copy the
screen to a file using save screen feature of the oscilloscope.
temperature
probe
5
781
metal case
35 oC
measure temperature on the
surface of regulator case
Deniz Yildirim
Feb 14, 2010
e1regtemp.eps
Figure 6. Measurement of case temperature for the linear regulator
Conclusion:
This experiment gives operational characteristics of a basic AC-DC converter by construct a
simple rectifier. Four diodes are used to rectify the incoming AC line voltage. Instead of
diodes, controllable solid-state switching devices such as thyristors can also be employed
where the use of thyristors will give the opportunity to control the output voltage without the
use of a linear regulator. This type of circuit containing controllable switches is called as a
controlled rectifier and is mainly used for speed control of DC motors. The experimental
analysis for such a circuit is the same as the one you have performed in this experiment.
However, the triggering circuit is a bit tricky and a proper design of a feedback control circuit
is necessary.
You must write a full report about what you have observed and what procedures you have
done to obtain these results. Compare your results with data sheets and other resources (text
book or references given below) or simulation analysis.
References:
[1] Introduction to Power Supplies, National Semiconductors Application Note 556,
September 2002.
[2] B. K. Bose, Modern Power Electronics and AC Drives, Prentice Hall 2002
[3] T. E. Kissell, Industrial Electronics: Applications for Programmable Controllers,
Instrumentation and Process Control and Electrical Machines and Motor Controls,
Prentice Hall, 3rd. ed., 2002.
[4] M. Brown, Power Supply Cookbook, Newnes 2nd. ed., 2001.
[5] D. W. Hart, Introduction to Power Electronics, Prentice Hall, 1997.
[6] J. W. Motto, Introduction to Solid State Power Electronics, Powerex |Inc., 1977.
[7] A. Kilian, Modern Control Technology: Components and Systems, 2nd ed., Delmar
Thomson Learning, 2007.
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Experiment 1, page 6/7
Last updated October 10, 2011 7:10 AM by D. Yildirim
EXPERIMENT RESULT SHEET
This form must be filled in using a PEN. Use of PENCIL IS NOT ALLOWED
EXPERIMENT 1: SINGLE-PHASE FULL-WAVE RECTIFIER AND LINEAR
REGULATOR
STUDENT NO
STUDENT NAME
SIGNATURE
DATE
1
2
3
4
INSTRUCTOR APPROVAL
Table 3
Multimeter Measurements
Vs (V)
Vsec (V)
Oscilloscope Measurements
Vdc (V)
Vsec (Vp-p)
Vdc (Vp-p)
Table 4
Oscilloscope Measurements
(ripple voltage peak–to–peak)
Vdc,ripple (V)
Vdc,ripple (V)
Vdc,ripple (V)
10 µF
500 µF
1000 µF
Rled (Ω)
Multimeter Measurements
(ripple voltage RMS value)
Vdc,ripple (V)
Vdc,ripple (V)
Vdc,ripple (V)
10 µF
500 µF
1000 µF
Table 5
No–Load Output Voltage
Vout,noload (V)
Rated Load Output Voltage
Vout,ratedload (V)
Table 6: Data for the rectifier from no load (0A) to full load (1000mA)
Pac (W)
Vdc (V)
Vout (V)
Iout (mA) Tcase (oC)
EE432 Industrial Electronics, Fall 2011
Experiment 1, page 7/7
Last updated October 10, 2011 7:10 AM by D. Yildirim