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Guidelines for Assignment
ELEC4613 – Electric Drive Systems
Total marks: 35 (worth 10% of the final marks)
The assignment for this course introduces you to simulation tools on a platform
(Matlab/Simulink) for studying the steady-state and dynamic behaviour of an example drive
system. These tools allow you to investigate the performance of a drive more elaborately than
is possible in a lecture or laboratory.
For the assignment, you will simulate an EV model accelerating on the road with a certain
slope angle. The EV model will be driven by a Permanent Magnet Synchronous Machine under
rotor field-oriented control (vector current control).
The machine and load parameters for your simulation are provided. The driving conditions,
voltage supply, converter arrangement and operating conditions for each task are also provided.
The assignment is worth 10% of your final assessment for this course. You will need to write
a technical report based on your simulation results. The report should consist of a description
of your simulation in terms of its goals, brief theory, and simulation data that you have collected
as your results. It must also include any plot of the data, operating characteristics in the form
of graphs, your conclusions/observations of the simulation results.
An example simulation model (on Simulink), a few important equations and some customised
simulation blocks related to the controller design are provided for easy implementation.
Normally, such simulation models help us to determine what controls and operating conditions
are required if some desirable performances (or goals) are to be achieved. You are expected to
critically discuss controller design and tuning process.
Your assignment must be submitted in the Assignment submission created in Moodle by the
submission deadline of 11:55 pm on 8 August (Week 11, Monday) 2022.
No late submission outside of Moodle will be accepted under any circumstances. If you fail to
submit due to medical reasons, you can apply for special consideration as per the UNSW
guidelines.
The Design Problem
An EV (say Tesla Model 3) has a Vehicle Mass of 1611 kg, wheel radii of 0.35 m, a fixed gear
ratio of 9.734:1 and a front area of 2.16 m2. This EV is driven by a PMSM with the following
parameters: pole number 𝑃𝑃 = 8, 𝐿𝐿𝑑𝑑 = 0.42 𝑚𝑚𝑚𝑚, 𝐿𝐿𝑞𝑞 = 0.52 𝑚𝑚𝑚𝑚, 𝑅𝑅𝑝𝑝ℎ = 0.028 𝑜𝑜ℎ𝑚𝑚, and
𝜆𝜆𝑚𝑚 = 0.23 Wb. It has a MOSFET bridge inverter with a carrier frequency of 50 kHz and a
rated current of 700 A. The battery has a nominal DC bus voltage of 600V.
(i)
Consider the EV having: friction coefficient = 0.3, aerodynamic drag coefficient =
0.23, and air density for drag = 1.225 kg/m3. The motor inertia can be included by
increasing the referred vehicle inertia to the motor side by a factor km = 1.08. Develop
a Simulink model of the EV mechanical loads with the motor torque Te and road slop
angle slop_deg as inputs. This EV block should be able to calculate the vehicle speed
(km/h), motor speed (rpm), and mechanical load torque applied to the motor (Nm).
The developed model should function as a stand-alone Simulink block, as shown in
Fig. 1 (the red block “EV Model”). After building the block, test it using the following
data – input slope angle as 0, 20 and 40 deg (one at a time) while keeping the input
motor torque fixed at a value calculated using the torque equation:
Tm
=
3
p λm iq + ( Ld − Lq ) id iq  where id = -183.7A and iq = 675.5A.
2 
Use a scope to note the acceleration time for each slope angle to reach a speed of
40km/hr. Present your test results in a table and confirm that EV acceleration time is
the fastest on a flat road.
(Hint: You should use the equations and knowledge from the Week 2 Workshop.)
(ii)
Develop a simplified EV drivetrain model with a Permanent Magnet Synchronous
Motor supplied from a DC source via a MOSFET full bridge 3-phase inverter. The
motor speed is controlled using the rotor field-oriented control (vector current control).
The EV model block of (i) is the load for the PMSM. An example of the developed
EV + drivetrain model is shown in Fig. 1. Note that the model in Fig. 1 is only an
example to give you a hint on how to connect various blocks. Please do not limit
yourself to the example model. You are more than welcome to build the model using
different blocks or in a different structure if you prefer. The red blocks are models you
must build by yourself using knowledge from this course. Do not use the Simulink
library block for these ones if they exist.
(iii)
To test your controllers, accelerate the EV from 0 km/h to two speeds in steps: 1) X
km/h, X is the last two digits of your zID(if the last two digits are 00, use the first two
digit), and 2) 100 km/h. It can be done easily by using the “Step” block to set the speed
reference. For this task, consider a flat road. Include the simulation results in your
report. Your simulation results should show the acceleration process in the following
plots – (1) Current ia, ib, ic, (2) motor speed and speed reference (rpm), (3) motor
torque (Tm), (4) Vdq, (5) iq and reference iq* , (6)id and reference id*, (7) EV speed
(km/h), and (8) motor load torque(TmL). An example of the expected results is
provided in Fig. 2.
To build the EV drivetrain model, you will need knowledge of RFOC, PI controller, VSI,
synchronous motor drive, abc-to-dq transformation (Clarke and Park transformation) and its
inverse forms, MTPA and FW, etc.
MTPA/FW block and a few other key modules with appropriate settings are provided as an
unfinished Simulink model “ELEC4613_Tesla_Blocks”. You may choose to use the model
structure and blocks provided in this file if you do not want to build them from scratch, and
we recommend you to use the mtpa&Fldwkn block from this file. If you use the provided
blocks, you must use the parameter and variables names exactly as they are used in those
blocks. A list of the key parameters/variables that must be defined or calculated using a Matlab
file (.m) before running the Simulink model is provided in Table 1. Please note that a Simulink
model is a discrete-time digital system (even if you run it in the continuous time mode).
Therefore, you must set two sampling times: Ts and Tcs, as listed in Table 1.
Note that ‘powergui’ block must be used when Simulink’s Specialized Power System library
blocks such as PMSM and Universal Bridge are used in a model. This block allows you to set
the simulation either in continuous or discrete mode.
Table 1. Example parameter/variable names
Stator phase resistance
d-axis inductance
q-axis inductance
Flux linkage
Total inertia (motor side)
Pole number/pair
Max. current peak
Max. phase voltage peak
Max. induced voltage peak
R
Ld
Lq
psi
J
P/p
Iam
Vam
Vom
Vehicle weight
Mev
Controller frequency
Controller sampling time
Simulink frequency
Simulink sampling time
Speed controller gains
Speed controller gains
Iq controller gains
Id controller gains
Base speed up to which
MTPA operates (rad/s)
Gravity
fc
Tcs
fs
Ts (1e-6 s)
Kp_spd
Ki_spd
Kp_q/ Ki_q
Kp_d/ Ki_d
wb
g
Note that Table 1 shows only key parameters. You will need to define other
parameters/variables, and you can name them as per your preference – as long as they do not
conflict with existing names and satisfy the Matlab variable name rules:
https://au.mathworks.com/help/matlab/matlab_prog/variable-names.html
For more information about Simulink and its sampling time, please check:
https://au.mathworks.com/help/simulink/slref/simulink-conceptsmodels.html#mw_62dc0547-ecd9-4fbd-bb67-2cda1631f1fe
Equations and Sample Codes
You should find most of the equations from your lecture notes, workshops, and tutorials.
Additional equations that may not be covered are provided below:
Vam =
Vdc
3
Vom = Vam − Iam ⋅ R
(1)
(2)
wb =
Vom
( psi + Ld â‹… Ida ) 2 + ( Lq â‹… Iqa ) 2
(3)
MTPA current reference calculation:
psi

 Ida =
psi
Iam 2

Lq − Ld ) −
+
4
(
2

2
4 ( Lq − Ld )


=
Iam 2 − Ida 2
 Iqa
(4)
You can use the following codes to calculate the controller constants of a discrete system
using the Pole Placement Method, especially if you use the discrete PI controller blocks
[PI(z)] in your simulation. Pole cancellation method with Bode plot that you learnt in Section
7 can also be used when you use PI controllers with continuous time [PI(s)].
%%%%%%%%%%%%%%%%%%%% Controller gains
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
fc =50e+3;% Sampling frequency of discrete controllers
Tcs=1/fc; %Sampling time of discrete controllers
Rs=R;
fcs= fc/10.0;%bandwidth frequency of current controller
%%%%%%PI constants for Current controllers in the discrete system (z-domain) %%%%%%
% https://au.mathworks.com/help/physmod/sps/ug/tune-an-electric-drive.html#bvn81uz-5
zeta=0.9; %Motor efficiency
wn=2.0*pi*fcs; % current controller bandwidth
sigma=exp(-zeta*pi/sqrt(1-zeta*zeta));
tr=6.0*zeta/wn;
Km=1.0/Rs;
Tmd=Ld/Rs;
Tmq=Lq/Rs;
b1d=Km*Tcs/Tmd;
b1q=Km*Tcs/Tmq;
a1d=(Tcs-Tmd)/Tmd;
a1q=(Tcs-Tmq)/Tmq;
Alpha1=-2.0*(1.0-zeta*wn*Tcs+0.5*(-zeta*wn*Tcs)*(-zeta*wn*Tcs)+1.0/6.0*(-zeta*wn*Tcs)*(zeta*wn*Tcs)*(-zeta*wn*Tcs))*cos(wn*Tcs*sqrt(1.0-zeta*zeta));
Alpha2=1.0-2.0*zeta*wn*Tcs+0.5*(-2.0*zeta*wn*Tcs)*(-2.0*zeta*wn*Tcs)+1.0/6.0*(-2.0*zeta*wn*Tcs)*(2.0*zeta*wn*Tcs)*(-2.0*zeta*wn*Tcs);
q0d=(Alpha1-a1d+1.0)/b1d;
q1d=(Alpha2+a1d)/b1d;
q0q=(Alpha1-a1q+1.0)/b1q;
q1q=(Alpha2+a1q)/b1q;
Kp_d=q0d
Ki_d=(q1d+Kp_d)
Kp_q=q0q
Ki_q=(q1q+Kp_q)
%%%%%%PI Calculation for Speed controller
K= 3*p*psi/(2*J); %% Includes inertial J, Pole pair number p, 3/2(torque/power coefficient of dq equation), PM
flux linkage psi.
f_spd=100; %bandwidth of speed controller in Hz
BW_spd=2*pi*f_spd;
Kp_spd=BW_spd/K;
Ki_spd=B/J; % B: Viscous damping coefficient
Fig. 1 Example Simulink Model of the EV model
Fig. 2 Example Plots of the EV Acceleration
Resources for writing technical reports:
If you have never written a technical report and would like to get some information, the
following link could be a good starting point:
https://www.theiet.org/media/5182/technical-report-writing.pdf
A few other handy ones:
https://www.wikihow.com/Write-a-Technical-Report
https://medium.com/technical-writing-is-easy/how-to-write-technical-report-e935210002c9
https://students.unimelb.edu.au/academic-skills/explore-our-resources/reportwriting/technical-report-writing
https://www.monash.edu/rlo/assignment-samples/engineering/eng-writing-technical-reports
If you want to pursue further, you may refer to these books:
1.
Davies J.W. Communication Skills – A Guide for Engineering and Applied Science Students (2nd ed.,
Prentice Hall, 2001)
2.
van Emden J. Effective communication for Science and Technology (Palgrave 2001)
3.
van Emden J. A Handbook of Writing for Engineers 2nd ed. (Macmillan 1998)
4.
van Emden J. and Easteal J. Technical Writing and Speaking, an Introduction (McGraw-Hill 1996)
5.
Pfeiffer W.S. Pocket Guide to Technical Writing (Prentice Hall 1998)
6.
Eisenberg A. Effective Technical Communication (McGraw-Hill 1992)
The marking of the report will be according to the marking rubric in the next page.
Technical Report Rubric (Assessment of Written Communications)
Item
Issues
Wgt
Writing
Overall
effectiveness
5
Clarity of
writing
Organisation
HD/D
100-85%
The writer’s decisions
about focus, organization,
style/tone, and content
made reading a pleasurable
experience. Writing could
be used as a model of how
to fulfill the assignment.
The purpose and focus of
the writing
are clear to the reader and
the organization and
content achieve the
purpose well. Writing
follows all requirements
for the assignment.
Credit
75-84%
The writer has made
good decisions about
focus, organization,
style/tone, and
content to
communicate clearly
and effectively. The
purpose and
focus of the writing
are clear to the reader
and or organization
and content achieve
the purpose well.
Writing follows all
requirements for
the assignment.
Pass
50-74%
The writer’s
decisions about
focus,
organization,
style/tone, and/or
content
sometimes
interfere with
clear, effective
communication.
The purpose of
the writing is not
fully achieved.
All requirements
of the assignment
may not be
fulfilled.
Fail
0-49%
The writer’s
decisions about
focus,
organization,
style/tone,
and/or content
interfere with
communication.
The purpose of
the writing is not
achieved.
Requirements of
the assignment
have not been
fulfilled.
3
Writing flows smoothly
from one idea to another.
The writer has
taken pains to assist the
reader in following the
logic of the ideas
expressed. Sequencing of
ideas within paragraphs
and transitions between
paragraphs make the
writer’s points easy to
follow.
Sentences are
structured and word
are chosen to
communicate
ideas clearly.
Sequencing of
ideas within
paragraphs and
transitions between
paragraphs make the
writer’s points easy
to
follow.
Sentence structure
and/or word
choice sometimes
interfere with
clarity. Needs to
improve
sequencing of
ideas within
paragraphs and
transitions
between
paragraphs to
make the writing
easy to follow.
Sentence
structure, word
choice, lack of
transitions and/or
sequencing of
ideas make
reading and
understanding
difficult.
Demonstration
of knowledge
2
Demonstration of full
knowledge of the subject
with explanations and
elaboration.
Writer is at ease with
content and able to
elaborate and explain
to some degree.
Writer is
uncomfortable
with
content. Only
basic concepts are
demonstrated and
interpreted.
No grasp of
required
subject matter.
No understanding
of
major issues. No
interpretation of
results
Flow of
information
2
Information is presented in
a logical, interesting way,
which is easy to follow.
Information is
presented in a logical
manner, which is
easily followed.
Work is hard to
follow as there
is very little
continuity.
Division of
information
2
All information is
located in the
appropriate section.
Some information
is in the wrong
section.
Many items are in
the wrong section
Sequence of
information is
difficult to follow.
No apparent
structure or
continuity.
Lack of
appropriate
sections or many
items
are in the wrong
section.
Report
Format and
aesthetics
1
Report format is consistent
throughout including
heading
styles, fonts, margins,
white space, etc.
A consistent format is
observed in all figures
and graphs.
Captions effectively
communicate
content
Report format is
generally consistent.
Many departures
from required
report format.
Work fails to
follow required
report format.
Figures and
Graphs
Format and
captions
1
Minor departures
from required
format or
inconsistencies
between figures and
graphs. Captions
effectively
communicate content
Work fails to
follow required
format. Captions
are ineffective in
communicating
content.
2
All figures are effectively
interpreted and
discussed in the
report.
Most figures are
properly interpreted
and important
features noted.
Citations
1
Citations consistent with
format.
Minor inconsistencies
referring to figures.
Many departures
from required
format or
inconsistencies
between figures
and graphs.
Captions are
ineffective in
communicating
content.
Many figures are
not
interpreted.
Important features
are not
communicated or
understood.
Many
inconsistencies
referring to
figures.
Effectiveness
Format and
captions
1
format is observed in all
tables. Captions effectively
communicate content.
Minor departures
from required
format or
inconsistencies
between tables.
Captions effectively
communicate content
Effectiveness
2
All tables are effectively
interpreted and discussed
in the
report.
Most tables are
properly interpreted,
and important
features noted.
Citations
1
Citations consistent with
format.
Minor inconsistencies
referring to tables.
Equations
Format and
citation
3
format is observed in all
equations. Citations
consistent with format.
Mechanics
Spelling
Grammar
2
3
Negligible errors
Negligible errors
Minor
departures from
required format or
inconsistencies
between equations.
Minor problems with
citation of equations.
Some symbols not
properly defined.
Minor errors
Minor errors
Tables
Many departures
from required
format or
inconsistencies
between tables.
Captions are
ineffective in
communicating
content.
Many tables are
not
interpreted.
Important features
are not
communicated or
understood.
Many
inconsistencies
referring to tables.
Figures are not
used
effectively. Little
understanding of
important features
or issues.
Citations fail to
follow required
format
or no citation
provided.
Work fails to
follow required
format.
Captions are
ineffective in
communicating
content.
Tables are not
used
effectively. Little
understanding of
important features
or issues.
Citations fail to
follow required
format
or no citation
provided.
Many departures
from required
format. Many
problems with
citation of
equations. Many
symbols not
properly defined.
Work fails to
follow required
format. Failed to
write correct
equations. Words
used instead of
symbols.
Several errors.
Several errors.
Numerous errors.
Numerous errors.
Readability
Noise-Free
3
Report was free of “noise
issues.”
Some instances of
“noise’’.
Many instances of
“noise.”
References
References
1
Reference section
complete, comprehensive
and follows
required format.
Minor inadequacies
in references
or inconsistencies in
format.
Inadequate list of
references or
failure to follow
required format.
Report plagued
with
distractions and
‘noise.”
No referencing
system used.

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