24V Power Supply Design: Project Report - Semester 1, 2024

Desklib provides past papers and solved assignments for students. This project details the design of a 24V power supply.

+24V Fixed
Power Supply

Contents
Introduction................................................................................................................................3
LO1 Plan a design solution and prepare an engineering design specification in response to a
stakeholder’s design brief and requirements..............................................................................4
a. Produce a design specification from a given design brief................................................4
b. Explain the influence of the stakeholder’s design brief and requirements in the
preparation of the design specification......................................................................................4
c. Produce a design project schedule with a graphical illustration of the planned activities.
....................................................................................................................................................5
d. Evaluate potential planning techniques, presenting a case for the method chosen..........5
e. Demonstrate critical path analysis techniques in design project scheduling/planning and
explain its use.............................................................................................................................6
f. Compare and contrast the completed design specification against the relevant industry
standard specification.................................................................................................................7
LO2 Formulate possible technical solutions to address the student-prepared design
specification specifications........................................................................................................9
a. Explore industry’s standard evaluation and analytical tools in formulating possible
technical solutions......................................................................................................................9
b. Assess the presented technical design and identify any potential limitation it may have.
..................................................................................................................................................13
c. Explain the role of design specifications and standards in producing a finished product.
..................................................................................................................................................15
d. Identify any compliance, safety and risk management issues present in the chosen
solution.....................................................................................................................................15
e. Evaluate the effectiveness of the presented industry standard engineering technical
design report for producing a fully compliant finished product..............................................15
LO4 Present to an audience a design solution based on the design report and evaluate the
solution/presentation................................................................................................................18
a. Present the recommended design solution to the identified audience............................18
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b. Explain possible communication strategies and presentation methods that could be used
to inform the stakeholders of the recommended solution........................................................19
c. Reflect on effectiveness of communication strategy in presenting the solution............19
d. Justify potential improvements to the presented design solution, based on reflection
and/or feedback obtained from the presentation......................................................................19
Conclusion................................................................................................................................21
Appendix..................................................................................................................................22
References................................................................................................................................25
List of Figures
Figure 1: List of Design Tasks...................................................................................................5
Figure 2: Gantt Chart.................................................................................................................6
Figure 3: Project Timeline.........................................................................................................6
Figure 4: PERT Chart.................................................................................................................7
Figure 5: Test Setup1 Schematics..............................................................................................9
Figure 6: Test Setup2 Schematics............................................................................................10
Figure 7: Chart 1: Evaluation of Testing Prototypes...............................................................10
Figure 8: Chart 2: Role of Prototyping in Formulating a Final Design...................................12
Figure 9: Block Diagram of Unregulated Power Supply.........................................................13
Figure 10: Transformer Section Behavior of Final Design......................................................14
Figure 11: Capacitor and Filtering Response (Rectifier’s Output Smoothing)........................14
Figure 12: : Role of Design Specifications in Overall Design Procedure................................15
Figure 13: (a) Current Response (b) Line Regulation (c) Load Regulation..........................17
Figure 14: Voltage Deviations.................................................................................................17
Figure 15: Design Hardware Presentation...............................................................................19
List of Tables
Table 1: Design Specifications...................................................................................................4
Table 2: Influence of Design Specifications..............................................................................4
Table 3: Comparison of Design Specifications with Industrial Standards................................7
Table 4: Design Benefits Presentation.....................................................................................18
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Introduction
Not all electronics equipment operating on a same voltage, thus require power supplies of
their operating voltage level. For this purpose, engineers mostly design supplies according to
the user’s voltage requirement. In our case, client acquired for design of a 24V power supply,
using Zener, transistors, or IC’s, any of these which gives compliance to power supply in
terms of uninterrupted ripple free output and cost-effective solution.
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LO1 Plan a design solution and prepare an engineering design specification
in response to a stakeholder’s design brief and requirements.
a. Produce a design specification from a given design brief.
Design Specifications
Power supply drives load containing device with a maximum power limit to 250watt
according to the external power supply regulations of the European Commission (EUR,
2009). In an initial meeting with client, design brief suggesting fixed 24V power supply was
presented by our stakeholders. Excellent regulation with uninterrupted long-lasting constant
output was the main requirement to be carried out in design process (Ellis, 2017). Hence, our
team analyzed and process stakeholders requirements prepared a design specification chart
shown below;
Table 1: Design Specifications
Input
Voltage
Output
Voltage
Standard
Efficiency
Rated
Current
Ripple and
Noise
Repulsion
Regula
tion
Dimens
ions
Ambient
Operating
Temperature
220~230
VAC
+24VDC 70~80% 2~3A ≤ 200mV IC’s or
Zener
Diode
1.5x2x
5 in
-5 ~ +80℃ ℃
b. Explain the influence of the stakeholder’s design brief and requirements in the
preparation of the design specification.
Our first preference is what client’s acquiring us to design. So we have prepared design
specifications setting client’s requirements as a standard and adding some industrial design
standards accordingly. Here is the chart showing how much stakeholder’s design brief helped
our team in preparing design specifications (Haidrar, 2017).
Table 2: Influence of Design Specifications
Stakeholder’s
Requirement
Influence
Constant Output
Minimum Noise and
Ripple
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Efficient and Cost
Effective
c. Produce a design project schedule with a graphical illustration of the planned
activities.
The very first step in defining a design schedule is to prepare a list of possible tasks to
perform. Design tasks lead any designer towards end result in a systematic order. That’s what
we have done while scheduling design of a product assigned. Following is the chart showing
a list of tasks that have been performed in design process (Özbek, 2016).
Figure 1: List of Design Tasks
d. Evaluate potential planning techniques, presenting a case for the method
chosen.
In order to monitor our project’s progress, we have prepared a Gantt chart showing what and
when to perform and what should be the status of design after each performed task. We’ve
found Gantt chart really helpful in keeping our team’s progress on track. Following is the
Gantt Chart showing our effort in each design step;
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Figure 2: Gantt Chart
When Gantt chart was prepared, we also thought of conducting a critical path analysis and
make a presentable timeline of our project. Project timeline below shows timing of each task
prior to next task (Sharon, 2017).
Figure 3: Project Timeline
e. Demonstrate critical path analysis techniques in design project
scheduling/planning and explain its use.
While preparing timeline, critical path analysis was done and then we made a PERT chart in
order to let our client understand how all the procedure carried out (Hundley, 2019). Every
task’s dependency upon other is being instanced and thus a graphical illustration of project’s
timeline is being shown below;
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Figure 4: PERT Chart
f. Compare and contrast the completed design specification against the relevant
industry standard specification.
Before starting our initial design, we have compared and analyzed our design specifications
against industrial standard design specifications of some 24V power supplies. We tried to
remain as close to those standards as we can, in designing power supply. Following table
compares design specifications with some industrial suppliers’ specifications and shows
which specification is above industry standards and which one is below. We have assigned 20
for below-standard, 40 defines a standard, and 60 for above-standard (Model, 2017).
Table 3: Comparison of Design Specifications with Industrial Standards
Specifications Current Design
Specifications
PWRPAK 24V
Power Supply
Standardizati
on Analysis
Input Voltage 220 ~ 230VAC,
60Hz
85 ~ 265VAC
47 ~ 63Hz
20
Output Voltage +24VDC 24V 40
Standard Efficiency 70 ~ 80% 82 ~ 84% 20
Rated Current 2 ~ 3A 2.2A 40
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Ripple and Noise Repulsion ≤ 200mV 150mV 60
Regulation IC’s or Zener
Diode QCL driver 20
Dimensions 1.5 x 2 x 5 in 1.46 x 3.23 x 6.3 in 20
Ambient Operating Temp. -5 ~ +80℃ ℃ -10 ~ +71℃ ℃ 60
Over Load and Over Voltage
Protection no yes 20
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LO2 Formulate possible technical solutions to address the student-
prepared design specification specifications.
a. Explore industry’s standard evaluation and analytical tools in formulating
possible technical solutions.
Test Setup1
First, we made a very simple design of a 24V power supply using LM7824 regulator to get
24V output. We integrated only three capacitors, two for Regulator’s requirement, and one
for reducing ripple in BR1 bridge rectifier’s output. LM7824 IC is been taken from a family
of LM7xxx regulator IC’s where 8 indicates positive output and 24 indicates output voltage
(Raajkumar, 2017).
Figure 5: Test Setup1 Schematics
Test Setup2
Secondly, a complete yet complex design was prepared and analyzed by our design team.
While designing it, first of all, our team decided to get rid of regulator IC and shift their
design towards adding Darlington pair transistor along with Zener diodes instead. C4 is used
for ripple rejection in final output coming out of Zener diodes. C1 reduces ripple in 24VDC
out of bridge rectifier. D1 ~ D4 make a bridge rectifier using 5407 diodes which were found
to be most suitable regarding Q1 and Zener diodes. Two Zener 12V and 13V mounted in
series make a 25V output whereas 1V is for ripple rejection. In this way, we got a perfect
24V output (Cheela, 2017).
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Figure 6: Test Setup2 Schematics
Test Setup3
In this design, we change the circuit simulator to run previous circuit one more time. Results
were somewhat better, but practically problem was same. So we replace C4 with 220uF/40V
capacitor, and also grounded C1 to provide short circuit path for extra voltages coming out of
bridge rectifier, i.e. 36V. In this way, we got success in getting constant ripple less output.
Industrial Standard Evaluation
It was carried out by taking into account the industrial standards to design a power supply.
Industrial requirements for a power supply helped us in testing and improving test setups
accordingly in order to provide reliable results in view of client’s requirements. Many
requirements of IEC/EN/UIL are confusing and focusing on IC’s and efficiency criteria that
is not suitable for our design as we need to make it cost-effective and easy-to-use for testing
other equipment using this. Anyhow, taking into account relevant and truthful IEC/EN
standards, we’ve evaluated our designs to achieve supervisory acquiescence (refer to
following chart).
T e s t S e t u p 1 T e s t S e t u p 2 T e s t S e t u p 3
4.3
2.5 2
2.4
5 6
2
4 4
1.5 3 5
Evaluating Test Setups
Regulation Linearity Ripple Rejection Protection
Figure 7: Chart 1: Evaluation of Testing Prototypes
Role of Test Setups in Formulating a Final Setup
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Role of Test Setup1
After testing our first prototype on a breadboard and taking readings, output was continuously
varying, and even decreasing from 24v to 17v which was completely inadequate as compared
to design requirements regarding ripple and noise. Moreover, we found out an unbalanced
behaviour of LM7xxx series towards voltages greater than 12v. In order to make a fully
compliant product, we needed many more complexity from grounding to current and voltage
protection and from constant output to ripple free output. Accordingly, it made us move
towards our 2nd test setup.
Role of Test Setup2
We analyzed our second test setup on 30W amplifier and it was running in low noise mode
making it appear to have some error in our design. We again analyzed same supply to run
another 24V motor which was also running slowly. We then decided to replace each
component of circuit with its near equivalent while noting output results after each
replacement. Transformer, capacitors, diodes, Zener, transistor, resistors, all were replaced,
and finally, we got some improvements to be made. These improvements lead us towards our
3rd test setup.
Role of Test Setup3
When this circuit was under consideration, we again tested it to run a 30W amplifier and a
24V motor, amplifier’s noise was now normal and 24V motor was also running ok. So this
was the point where we decided to finalize our design solution and in this way design evolved
towards required solution. Below chart shows the role of all three conceptual designs in
formulating a final solution.
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