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EEE349/EEE350 – Sem1 ‐ Assignment
发布时间：2021-12-30
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Power Engineering Electromagnetics ‐ EEE349/EEE350 (2021‐2022)
EEE349/EEE350 – Sem1 ‐ Assignment
Introduction
‐ This assignment depends on Sem 1 material.
‐ The assessment will be based on MATLAB and FEMM4.2 software
‐ The assignment might contain elements that have not been covered in
the lectures.
‐ You should provide all workings and explanations in your solutions. Also,
justify your design selection, if any. These will variously count towards achieving full marks in this assessment.
‐ The MATLAB and FEMM4.2 are not examinable in either TA or GA
examinations.
‐ For individual values of the problem parameters, If you see the letter ‘m’
in the question or figures, this represents the last digit of your registration
number. For example, if your registration number is
So, you will substitute every ‘m’ by the number 7.
If your last digit in your registration number is ‘0’, you will substitute the ‘m’ number by 10.
Submission Details
You can complete your answers as a word‐processed document or as handwritten sheets (The word document is preferred). Please save or scan these respectively into a pdf file. Copy your MATLAB code and any graphs into a word document, then save them into a pdf file. Also, any figures or graphs out from FEMM4.2, copy it to a word document. As this submission is considered a formal report, The first‐page template is added to the same folder. Convert the first page into pdf format.
This assignment has three questions. Question 1 is a MATLAB code, and question 2 is an electrostatic problem, while question 3 is an electromagnetic problem. The assessment is distributed in 6 pages (page 1 includes the introduction, page 2 includes the submission details, while pages 3 to 6 contain the questions). It is recommended to add a summary page for questions 2 and 3.
Upload and submit your work as one pdf file via MOLE (BlackBoard) under the content area ‘Sem1‐Assignment 2021‐2022’; Please do not zip your pdf.
The deadline for submission is 23:59 on Tuesday, February 15th 2022.
Grades and feedback will be released no later than three weeks after the deadline.
The report will be marked out of 100
Question 1 is out of 10 marks
Question 2 is out of 40 marks
Question 3 is out of 45 marks
Report organisation and presentation is out of 5 marks
This assignment (questions 2 and 3) is a MUST‐PASS ELEMENT. The minimum grade to pass is 40 %. i.e. the minimum mark for question 2 is 17 marks, and the minimum mark for question 3 is 19 marks.
Question 1 [10 marks]
It is required to build an M‐code using MATLAB to confirm that if balanced three‐phase currents with amplitude Imax and with an N number of turns, a rotating field with a circular nature is produced. Take the maximum current value 2*m A and the number of turns is 100 turns.
Show that the field nature is ellipse if there is unbalance in either magnitude or shift. Confirm your code using the following cases.
a‐] ia(t) = m sin(
t) A, ib(t) = 2m sin(
t‐120
) A, and ic(t) = 1.5m sin(
t+120
) A b‐] ia(t) = m sin(
t) A, ib(t) = m sin(
t‐90
) A, and ic(t) = 1.5m sin(
t+120
) A
Question 2 [40 marks]
A single core lead sheathed cable with voltage (60+m) kV shown in figure (1) has a conductor radius a = (15 + m/2) mm and two layers of insulating material with relative permittivity 
r1 and 
r2, respectively. Choose the material of layer one as Polypropylene with 
r1=(2+0.1m). Choose the material of layer two as PVC with 
r2 = (4+0.1m). The outer radius is b = (25 + m/2) mm. The conductor is copper (You can add a new property as a copper conductor, select a proper value for the permittivity of the copper conductor. Remember to add a boundary for your problem.
The problem conditions:
‐ Electrostatic problem
‐ Choose planar solution,
‐ Length units in millimetres, and
‐ Depth 1000 mm.
‐ Choose your mesh for not higher than 0.5 mm for improving the accuracy
of the solution.
In your report,
Add vertical and horizontal contours (C1, C2, C3, and C4) to your schematic, then
a‐] Attach your schematic diagram with the required contours and test half of the cable with the Polypropylene insulator. Plot the voltage distribution across contours, comment on your results. Plot the electric field distribution across contours, comment on your results. Note: use a separate graph for each contour.
b‐] repeat part [a] by adding the second half of the cable with the other
insulating material
Note: use a separate graph for each contour
c‐] Plot the electric field tensor
d‐] Find the cable capacitance using FEMM4.2 software, then confirm your answer analytically
Question 3 [45 marks]
A variable inductance can be represented by the magnetic circuit shown in figure (2). X represents the dimension in mm where x = (15 + m /4) mm and k factor equals 2.5. Choose the iron material from the FEMM4.2 library as a Mild‐steel M‐50. The number of turns of the coil is (70+m) turns.
The problem conditions:
‐ Electromagnetic problem
‐ Choose planar solution,
‐ Length units in millimetres, and
‐ Depth 1000 mm.
‐ Choose your mesh for not higher than 0.5 mm for improving the accuracy
of the solution.
In your report,
1‐ Attach a schematic diagram with the required contours. (Remember to add a boundary to your problem)
2‐ Calculate the coil current if the current density is (3.8+0.05m) A/mm2 .
The filing factor is 55 %.
3‐ Calculate the coil inductance, 
if the air gap equals 1 mm and 5 mm (Note: ignore the air material in the plunger. This space is used to fix the plunger in the circuit; hence it is considered as air or non‐magnetic material)
4‐ Plot the flux distribution and flux tensor across the contour for the air gap limits.
5‐ Plot the normal flux density component.
6‐ Measure the flux density in the air gap
7‐ Measure the inductance and compare it with the calculated one in number 2. Hint: integrate the vector A for the left coil (in and out current). You will get the result Henry*Ampere, and this result is per turn. Plot a relation between the inductance and the airgap in steps where g is the x‐axis and the inductance is the y‐axis (g starts from zero up to 5 mm, take 1 mm step)
