Power Electronics Lab
By: Alex M. Bermel
ECE 409: Electrical Engineering Senior Project
April 20, 2011
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Table of Contents
Title page
1
Table of Contents
2
Project Scope
4
Problem Statement
4
Health and Safety
5
Customer Needs
6
Economic Analysis
6
Social Analysis
7
Political Analysis
7
Sustainability and Economic Analysis
8
Needs Metric Matrix
9
Requirement Specifications
10
Product Design Specifications
11
Concept Generation
14
Prototype Testing Plan
15
-2-
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Alternative Solutions
16
Project Timeline
17
Prototype Estimated Cost and Budget
18
Results and Conclusion
19
References
29
Appendix
30
-3-
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Project Proposal
Project Scope
The objective of this project is to provide a group of adequate experiments that can be
sustained in a college level laboratory. Using a Power-pole board, descriptive lab reports will
explain to students how to wire and show the results of a Buck Converter, Boost Converter,
Buck-Boost Converter, Flyback Converter, and Forward Converter. The scope of this project
includes becoming familiar enough with the Power-pole board to help monitor a Power
Electronics Lab.
Problem Statement
Electrical Engineering undergraduate students are not receiving enough practical
laboratory experience while attending university. By implementing a Power Electronics
Laboratory course, students will benefit greatly from the experience attained and will show
competency when dealing with or asked about electronic devices and applications of power
electronics. The resources needed to complete this project are miniscule. Any university can
implement this lab course by ordering a Power-pole board and setting up a station, with a
power supply, in one of their laboratory areas.
-4-
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Health and Safety
Attention and adherence to safety considerations is even more important in a power
electronics laboratory than is required in any other undergraduate electrical engineering
laboratories. Power electronic circuits can involve voltages of several hundred volts and
currents of several tens of amperes. By comparison the voltages in many teaching laboratories
rarely exceed 20V and the currents hardly ever exceed a few hundred milliamps.
In order to minimize the potential hazards, we will use dc power supplies that never exceed
voltages above 40-50V and will have maximum current ratings of 5A or less. However in spite of
this precaution, power electronics circuits on which the student will work may involve
substantially larger voltages (up to hundreds of volts) due to the presence of large inductances
in the circuits and the rapid switching on and off of amperes of current in the inductances. For
example a boost converter can have an output voltage that can theoretically go to infinite
values if it is operating without load. Moreover the currents in portions of some converter
circuits may be many times larger than the currents supplied by the dc supplies powering the
converter circuits. A simple buck converter is an example of a power electronics circuit in which
the output current may be much larger than the input dc supply current. Check for all the
connections of the circuit before powering the power-pole board to avoid shorting or any
ground looping that may lead to electrical shocks or damage of equipment.
-5-
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Customer Needs
For this specific project the customers will be the students and universities that decide
to implement a Power Electronics Lab. Besides the safety of the students, the next most
important need for customers is accuracy in the results.
The current customer needs are as follows:

The university needs to have a few Power Pole Boards that the students can work with.

Efficiency of the results would mean the measure of efficiency must be accurate
enough to produce a common result in the lab.

Convenience is quintessential. The customer always comes first, so the board must be
easy to implement.

Expenses must be in a reasonable range for universities to consider implementing a
Power Electronics Lab in their curriculum.
Economic Analysis
Since resources are scarce in order to fulfill the Power Electronics Lab course it is very
economical to implement. The Power-pole board is the main; if only, rarity item that will be the
most costly. The Power-pole board that can be used is manufactured by HiRel Systems and
costs $1250. This price includes three attachments necessary to achieve the desired
experiments needed for the course. Basic engineering tools are needed, such as electrical
probes and multimeter to attach to the circuit and analyze different points on the Power-pole
-6-
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
board. A Digital Oscilloscope with a RS232 interface is needed to view the current or voltage
waveforms across the circuit and can be bought for $400 online. A power supply is needed as
well and would cost $50-$100 depending on which company you decide to use. However, a
power supply, digital oscilloscope, probes, and multimeter are very common in engineering
labs.
Social Analysis
From an anthropologic standpoint, humans are always trying to excel further to produce
the most optimal technologies or ideas. It is our biological characteristics that move us to
becoming better people, hence better engineers. By creating this lab the students’ perspectives
on Power Electronics will change and they will receive a more fundamental understanding of
the way power works in the field of engineering.
Political Analysis
The contributions made for this project will be from the university itself. In an ideal
world, the university hosting the Power Electronics Lab should be funding the necessary needs
for the students. The reason they should supply monetary contribution for the project is
because a university’s goals are to teach students new ideas so that they can apply them to
society and benefit the world by making a more sustainable place. There are really no negative
impacts associated with this project since knowledge is a priceless tool that never ceases to
prosper in someone. The individuals that play a role in this project are the students; it is their
-7-
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
responsibility to make the best out of their college experience. Since most college students are
there for themselves, they should be keen to playing their role by obtaining the knowledge
necessary to make this project a success.
Sustainability and Environmental Analysis
The world we live in strives to be more sustainable every day. Power Electronics deals
with maximizing the efficiency of input power versus output power. Efficiency should be a
businesses’ biggest concern because it minimizes expenses since there would be very little
power loss in an efficient system. Not only does it inevitably save any company money, but it
also benefits the environment by reducing carbon emissions and the use of fossil fuels when
they are making use of all the inputting power to get the most output power. The modern day’s
society is becoming more and more fixated with reducing their ecological footprint, which
means that companies are more willing to hire engineers that have the knowledge of power
applications that can help save the planet.
-8-
NEEDS
Accuracy
Availability
Productivity
Convenience
Easy Use
Inexpensive
Safety
Professionalism
X
X
X
X
X
X
X
X
Availability of resources
Are the readings accurate enough
No potentially harmful voltages
Can be afforded by Universities
Problems can be fixed in a reasonable time
X
X
X
Can be carried around campus
Can test under Lab Time requirements
METRICS
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Needs-Metric Matrix
X
X
X
X
X
X
-9-
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Requirement Specifications
In order for this project to be executed correctly the five converter experiments must be
tested and performed with accurate results and procedures so that they can be repeated by
students so that they can learn from it. Many of the tasks that must be performed include:
analyzing, documenting, validating and managing project requirements. The laboratory results
must be documented for future use. The use of the Digital Oscilloscope will be used to analyze
the input and output waveforms and observe the actions of each experiment. Documentation is
the most important requirement specification because it will be the sole evidence needed in
order to fulfill the needs of the student and make the project Power Electronics lab a success.
- 10 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Product Design Specifications
Figure 1: The Power-pole board and its three converter boards.
This project is supposed to give real life applications of circuits. Other than obvious
power efficiency exercises, I will demonstrate how these converters can be applied to the
Power-pole board and positively affect today’s society technologies. In order to create this
project:
 The Buck converter will demonstrate reduction in output voltage using a transistor and
a diode that have a constant DC current running through both. Energy conservation is a
key concept in power electronics. An application of this is in a "maximum power point
tracker" commonly used in photovoltaic systems. Maximum power point tracking
- 11 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
(MPPT) is a technique that solar battery chargers and similar devices use to get the
maximum possible power from the photovoltaic array or array of solar panels.
 The Boost converter does exactly what its name suggests. It will create an output
voltage higher than the source voltage. A normal battery powered system will stack cells
in order to increase output voltage. However, this is sometimes impossible in high
voltage systems due to lack of space. Boost converters are very efficient because they
increase voltage in a system while minimizing occupied space. An application of this is
that the NHW20 model Toyota Prius HEV uses a 500 V motor. Without a boost
converter, the Prius would need nearly 417 cells to power the motor. However, a Prius
actually uses only 168 cells and boosts the battery voltage from 202 V to 500 V using a
boost converter. Another smaller scale example would be in portable lighting systems.
A white LED typically requires 3.3 V to emit light, and a boost converter can step up the
voltage from a single 1.5 V alkaline cell to power the lamp.
 The Buck-Boost converter will create an output voltage that is greater than or less than
the source voltage depending on the state of the switching transistor in the circuit.
When the switch is closed, which is known as being in the ON state, the input voltage
source is directly connected to the inductor, which results in accumulating energy in the
inductor, which directly results to the capacitor supplying energy to the output load.
While in the OFF state, the inductor is connected to the output load and capacitor, so
energy is transferred from L to C and R.
- 12 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
 The Flyback Converter can be used in both AC to DC and DC to AC conversion. Basically,
a flyback converter is a buck-boost converter with the inductor split to form a
transformer. This results in a voltage ratio multiplication and isolation advantages.
When the switch is ON state, it creates magnetic flux in the transformer and the diode
(indicated as D in Appendix A figure 4) becomes reversed biased and no current flows
through it so that the output capacitor now supplies energy to the output load. When
the switch is OFF state, the energy in the transformer is transferred to the output of the
converter. Applications for this vary from high voltage generation systems like a CRT in a
TV/monitor, or in lasers to low power switch mode power supplies like cell phones
chargers.
 The Forward converter is a DC to DC converter that uses both boost and buck converter
to provide galvanic isolation, which is the principle of isolating a section of an electrical
system. We see this concept used in transformers. A forward converter performs the
same operations as the flyback converter, but the forward converter is much more
efficient.
- 13 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Concept Generation
The project has one main idea, which was chosen due to its particular advantages. It did,
however, have its malfunctions and complications that had to be managed throughout the
project.

Category A: The Main Idea
Power Electronics plays a crucial role in minimizing energy consumption. Energy
conservation leads to financial savings and benefits the environment at the same time.
A Power Electronics class would be a very vital course in any engineers’ curriculum. It
would teach engineers the importance of reaching maximum power efficiency in a
system. This is something that a new rising generation should be aware of and many
corporations in the energy field will be interested in students that are knowledgeable in
this field. Since employers are always looking for employees with field experience,
there’s no better place in school to get that then in a course Lab corequisite.

Category B: The Options
Since other universities have already implemented this idea in their classes, I
researched different universities and found that the University of Minnesota has had
great success in experimenting with a Power Electronics Lab for their students. They use
a Schott Power Systems Power-pole board which was available during the start of their
program. Yet, due to advancement in technologies a better board to use is
manufactured by HiRel Systems LLC. This is the Power-pole board that will be used in
- 14 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
this project. The University of Minnesota’s lab manual is viewable to the public. It has
little explanations to the theory behind their results.
Prototype Testing Plan
Testing the Power-pole board is a key plan in any project. Testing occurred in the
beginning stages of the project to see what each component on the Power-pole board does and
should do. To test the daughter board connector (J60) plug in the ±12 V signal supply at the
DIN connector and using a DMM Multimeter touch pins 1 and 20 to get a positive 12V display
and 3 and 18 to get a negative 12V display. This should ensure that your signal supply is in fact
±12 V. Each of the six converters have a different purpose so in order to make sure each one is
properly connected a frequency analysis can be done. Frequency analysis of any converter can
be done by injecting a low voltage sinusoidal signal at jumper (J64) also known as the smallsignal AC analysis selection jumper. The use of the Oscilloscope makes sure the output voltages
are correct and each converter is acting as they are supposed to in theory.
- 15 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Alternative Solutions
Below is an alternative board called the µModule LED Driver board. It can perform the
buck, boost, and buck-boost experiments as well as other topologies. It accepts an input
voltage of 3- 30 Volts and supports an output voltage up to 32 Volts.
Figure 2: The alternative µModule LED Driver board.
- 16 -
Week 16 (December 6th – 12th)
Week 15 (Nov. 29th – Dec. 5th)
Week 14(November 22nd -28th )
Week 13 (November 15th -21st)
Week 12 (November 8th- 14th)
Week 11 (November 1st- 7th)
Week 10 (October 25th- 31st)
Week 9 (October 18th- 24th)
Week 8 (October 11th- 17th)
Week 7 (October 4th- 10th)
Week 6 (Sept. 27th- Oct. 3rd)
Week 5 (September 20th-26th)
Week 4 (September 13th-19th)
Week 3 (Spetmber6th -12th)
Week 2 (Aug. 30th –Sept. 5th)
Week 1 (August 23rd -29th)
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Project Timeline
Project Planning
Ordering of Parts
Testing of Parts
Project Designing
Wiring Circuit
Testing Circuit
Writing Report
Presentation
- 17 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Prototype Estimated Cost and Budget
As of now the Cost and Budget for this Project is the Power-pole Board. We are using a
company called HiRel Systems LLC to order our Power-pole Board that charges $1,250. While
testing the Power-pole board a few complications were uncovered. Due to an unknown
variable, the two 250 mA fuses went over their specified current rating and blew. To replace
and make sure this does not happen again I bought five 250 mA and 250 V radial fuses that met
the right requirements for the Power-pole board we are using. This costs about $3.36 plus a
$2.22 shipping and handling fee. Regardless of my efforts, the board blew another fuse and
became apparent that there was a manufacturing error in one of the micro-controllers. HiRel
Systems agreed to take a look at it and fix it, but they said it would cost approximately $300500 range depending on the problem.
- 18 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Results and Conclusions
Buck Converter: Output Voltage
Table 1: The theoretical and actual output voltages (Vo) for the Buck Converter
(Vin=24 V
Duty Cycle D [%]
f= 100 kHz
L= 106.6 µF
Theoretical Output Voltage Vo [V]
RL= 10 Ω)
Actual Output Voltage Vo [V]
Vo= Vin*D
0
0
0.333 mV
10
2.4
2.39
20
4.8
4.5
30
7.2
7.11
40
9.6
9.4
50
12
12.1
60
14.4
14.5
70
16.8
16.77
80
19.2
19.2
90
21.6
19.7
100
24
20.1
- 19 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Vo [V]
Theoretical vs. Actual
27
24
21
18
15
12
9
6
3
0
Theoretical
Actual
0
10
20
30
40
50
60
70
80
90 100
Duty Cycle [%]
Figure 3: The theoretical and actual output voltages of the Buck Converter.
Observation: The Buck converter accurately follows the equation VO = D*Vin, and so behaves as
a DC step down transformer with turns ratio 1:D.
The Buck Converter in fact acts like a DC step down transformer. The study of a nonisolated Buck Converter is observed and proven to have a turns ratio of 1:D. The output voltage
follows the equation VO = D*Vin very accurately until the duty cycle (D) reaches 90% where it
then begins to show some inefficiency. We measure efficiency of the Buck Converter by as η =
(VO*IO)/ (Vin*Iin) at two different frequencies. We find the currents through using the current
sensors or applying an amp meter across the input and load.
- 20 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Boost Converter: Output Voltage
Table 2: The theoretical and actual output voltages (Vo) for the Boost Converter
(Vin=10 V
Duty Cycle D [%]
f= 100 kHz
L= 106.6 µF
Theoretical Output Voltage Vo [V]
RL= 20 Ω)
Actual Output Voltage Vo [V]
1
Vo=[1−𝐷 ∗ 𝑉𝑖𝑛]
10
11.1
11.2
20
12.5
12.7
30
14.2
14.5
40
16.667
16.0
50
20
19.6
60
25
21.0
- 21 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Theoretical vs Actual
30
Output Voltage [V]
25
20
15
Theoretical Values
10
Actual Values
5
0
0
10
20
30
40
50
60
Duty Cycle [%]
Figure 4: The theoretical and actual output voltages of the Boost Converter
Observation: Because the current rating of the function generator the maximum duty cycle
should be 60% or else you risk blowing a fuse in your circuit. As you increase the duty cycle the
voltage increases. The actual voltage at 60% is not accurate with the theoretical value because
of the current ratings and voltage ratings of the equipment.
The Boost converter can be seen to follow the principles of a power converter by having
a larger output voltage than input voltage. It can be observed that when the switch is in the ON
position the current flows freely through the inductor and energy is stored into it. However,
during the OFF state, the stored energy collapses and is released from the inductor and the
polarity changes so that it adds more voltage to the input. The results show that the Boost
1
converter does follow the equation Vo = [1−𝐷 ∗ 𝑉𝑖𝑛].
- 22 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Buck-Boost Converter: Output Voltage
Table 3: The theoretical and actual output voltages (Vo) for the Buck-Boost Converter
(Vin=10 V
Duty Cycle D [%]
f= 100 kHz
L= 106.6 µF
Theoretical Output Voltage Vo [V]
RL= 20 Ω)
Actual Output Voltage Vo [V]
𝐷
Vo=𝑉𝑖𝑛(1−𝐷)
10
20
30
40
50
60
70
1.11
0.853
2.5
2.07
4.29
3.97
6.68
6.11
10.15
9.34
15.18
13.94
23.31
19.89
- 23 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Vo [Volts]
Chart Title
27
24
21
18
15
12
9
6
3
0
Actual Output Voltage
Theoretical Output
Voltage
0
10
20
30
40
50
60
70
80
Duty Cyle [%]
Figure 5: The theoretical and actual output voltages of the Buck-Boost Converter
Observation: The measured values are lower due to the resistive voltage drops occurring in the
inductor, current sensors, switch, and diode which therefore make the measured values lower
than the theoretical values.
The Buck Boost Converter performs in respect to the output voltage, ripple current. The
efficiency is reasonably close to the expected performance. In practice the measured values are
lower due to the resistive voltage drops occurring in the inductor, current sensors, switch and
diode due to which the measured values are lower than theoretical values. By considering these
voltage drops a better match between theory and measurement can be seen. The results
𝐷
follow the expected values by the theoretical formula Vo=𝑉𝑖𝑛(1−𝐷) .
- 24 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Flyback Converter: Output Voltage
Table 4: The theoretical and actual output voltages (Vo) for the Flyback Converter
(Vin=15 V
Duty Cycle D [%]
f= 100 kHz
L= 106.6 µF
Theoretical Output Voltage Vo [V]
𝑁2
RL= 10 Ω)
Actual Output Voltage Vo [V]
𝐷
Vo=𝑉𝑖𝑛 ∗ (𝑁1) ∗ (1−𝐷)
0
10
20
30
40
50
0
0.002
0.833
0.56
1.875
1.33
3.2
2.67
5.0
3.97
7.5
5.66
- 25 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Outputput Voltage vs Duty Cycle
8
OUtput Voltage Vo[Volts]
7
6
5
4
Theoretical
3
Actual
2
1
0
0
10
20
30
40
50
Duty Cycle D[%]
Figure 6: The theoretical and actual output voltages of the Flyback Converter
Observation: The above theoretical formula assumes that the MOSFET and Diode are ideal and
have 0 V drop. However, in the actual results, the drop in each switch can be approximately 0.6
V which is significant considering that output voltage is only 5 V. This accounts for error
between the calculated and measured values of Vo.
The Flyback converter results show that the observed performance of the Flyback
converter is moderately close to the expected performance. The input current and output
current are correlated to the turns ratio. It has been determined that the ripple in the input
current depends on the input voltage, duty cycle, and the frequency applied to the circuit. The
exponential increase in the output voltage is expected as the duty cycle increases. The output
𝑁2
𝐷
voltage results follow the expected formula of Vo=𝑉𝑖𝑛 ∗ (𝑁1) ∗ (1−𝐷).
- 26 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Forward Converter: Output Voltage
Table 5: The theoretical and actual output voltages (Vo) for the Forward Converter
(Vin=20 V
Duty Cycle D [%]
f= 100 kHz
L= 106.6 µF
Theoretical Output Voltage Vo [V]
RL= 10 Ω)
Actual Output Voltage Vo [V]
Vo=𝑉𝑖𝑛 ∗ 𝐷
10
2
1.50
4
3.4
6
5.21
8
7.05
20
30
40
- 27 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Ouput Voltage vs Duty Cycle
9
Output Voltage Vo [Volts]
8
7
6
5
4
Theoretical
3
Actual
2
1
0
0
10
20
30
40
50
Duty Cycle D [%]
Figure 7: The theoretical and actual output voltages of the Forward Converter
Observation: It is observed that the output voltage predictably follows the theoretical formula.
There is a miniscule difference due to the voltage drop across the MOSFET switch, diode, and
other components.
The Forward Converter’s output voltage, as shown above, increases linearly as the duty
cycle increases. There is approximately a 0.5 V voltage drop due to the diode and switch in the
circuit. The measurement of current at input indicates that during the OFF period the input
current is negative due to the reverse current flow from the tertiary winding. The output
voltage did follow the equation 𝑉𝑖𝑛 ∗ 𝐷 respectfully.
- 28 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
References
Power Electronics by Ned Mohan
Power Electronics by Daniel W. Hart
Internet
University of Minnesota Power Electronics Lab
John H. Ventura
- 29 -
Alex Bermel
ECE 409
John Ventura
April 20th, 2012
Electrical Engineering Senior Project
Appendix A
Figure 1: Buck Convertor
Figure 1: Buck Convertor
Figure 3: Buck Boost Convertor
Figure 2: Boost Convertor
Figure 4: Flyback Convertor
Figure 5: Forward Convertor
- 30 -