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21-JAN-2020EIEN20
Design of Electrical Machines
1. Introduction Course overview Electromechanics
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 2
L1: Introduction•
Terminology
–
Design–
Electric
–
Machine•
Course content
–
Targets and topics–
Learning phases
•
Sources–
Slides, assignments and tutorial
–
Wikipedia
•
Electromechanical energy conversion
and
Electromagnetism –
Lorentz
force
–
Electromagnetic induction•
Conservation of energy
–
The First Law of thermodynamics
–
Energy conversion efficiency
W
W
W
W
W
W
W
Rational
construction
for efficient
energy
conversion
W
W
W
Engineering
apps
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 3
Energy density•
Medium ability to maintain magnetic
field or/and
electric
field•
The permittivity ε
is for
polarization whereas the permeability μ
is for
magnetization•
Flux density
in the air-gap
•
Bg
=1T → ~400000 J/m3
> PM•
Break down field
for air
•
Eb
=3kV/mm → ~40 J/m3
•
Compare energy density [MJ/Lit] and specific energy [MJ/kg]
VmAs
mF
cEED
AmVs
mHBHB
ED
HB
9
020
0
20
70
0
2
1036
1122
10422
Storage material MJ/L MJ/kg Liquid hydrogen 10 142Diesel 35.8 48Lithium metal battery 4.3 1.8Lithium-ion battery 2.6 0.8carbohydrates 43 17
Electromechanical energy conversion in presence of magnetic field
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 4
Accommodate Energy Conversion•
Investigate
electromagnetic
components: inductors, transformers, actuators, machines that operate as motors or generators
•
Use numeric field computation tools to test your ideas
•
Set up your own
model and material libraries for design experience and competence
development
W
W
W
WW
W
W
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 5
Learning spacePower of understanding• energy conversion• material properties• machine construction
Power of imagination• integration• production
Creativity
B
IF
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 6
Prior/Parallel knowledge•
Ohm’s Law
•
1φ
/ 3φ•
Cause of electro-magnetic force (F [N]) and torque (T [Nm])
•
Magnetic flux ([Vs)], flux linkage ([Vs]) vs. electromotive force (E[V]), electric current (I[A]) vs. magnetomotive
force (F[A])
–
Maxwell’s equations •
Power electronic control
–
Variable-frequency
drive
W
WW
W
W
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 7
Expectations•
What would you like to know?
•
What would you like to learn? •
What do you expect from this course?
–
Mentimeter
quiz•
Motivation (U): 7.5 credits + knowledge (as bonus)
•
Requirements (R):–
28+4 hours of lectures
–
>50 hours of project–
>90 hours of self-studies
•
Easiness (I): I=U/R
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 8
Learning progress•
Learning process
–
14x2 lectures (LP3)–
5 weekly home assignments (LP3)
–
Course project (LP4) and related workshops
•
Assessment–
Completed home assignments and approved design report & presentation grants the grade 3. For higher grade a written exam is required.
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 9
Advancements•
Multidisciplinary & -
dimensional–
Construction + production
–
Energy conversion processes + analysis tools
–
Materials + properties•
From component towards application and system
–
Imagine, Explore, Learn, Think & Know
–
Starting from simpler geometries, formulations and applications
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 10
Course goal
•
Objective of this course is to gain experience covering the overall design process: design, construction specification and realization analysis, exploitation and testing of an electromagnetic device
•
Understand
the electromechanical design behind the classical electromagnetic devices
PreparationGoverning Laws andModeling Techniques
PracticeDesign experience:
Identify target & model library
DevelopmentHardware oriented
Analysis & modeling skills
Design Thinking W
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 11
Course plan
•
Preparatory: Lectures (L) in thematic pairs & prsetudy
and preselection
of project topics and teams (W8)
–
Individual Assignments (A) completed and reported within 2 weeks
•
Specialization: project oriented lectures and seminars (S)•
Project: execution, completion and presentation (W22)
W4 W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 W17 W18 W19 W20 W21 W22L13 L14 L15 S6 S8 S10 S12 S14
L1 L3 L5 L7 S1 L9 L11S3 S4 S5 S7 S9 S11 S13 S15
L2 L4 L6 L8 S2 L10 L12
A1 A2 A3 A4 A5
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 12
Thematic pairs•
Overview
–
L1
introduction
to topics–
L2 survey
on machines
•
Modelling
techniques–
L3: equivalent
circuits
–
L4: finite element method
•
Energy conversion–
L5: electromagnetics
–
L6: electromechanics
•
Magnetic+electric circuits–
L7: magnetic
cores
–
L8: electric
windings
•
Heating and cooling–
L9: power
losses
–
L10: thermal
design
•
Design issues
and realizations
–
L11: torque
capability–
L12: power capability
•
Application
orientation–
L13: traction
–
L14: power generation–
L15: aviation
•
Retrospect & outlook
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 13
Home assignments•
Introduction to computational techniques and software –
optimization of a
transformer•
Magnetic analysis and characteristics of a transformer
•
Torque capability and thermal analysis of a PMSM
•
Magnetic analysis and characteristics of a PMSM
•
Machine types, models and characteristics
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 14
Course project
•
Project topics from thematic areas–
Analysis an design of electromagnetic components (1)
–
Application oriented components and system perspective (2)–
Material development and production (3)
–
Measurement and diagnostics (4)–
Self specified topic (5)
•
Project developer team 1-3 students–
Projects can be closely related
•
Article and presentation
is expected from the project
DiscoveryConcept and Feasibility
DeliveryImplementation
DevelopmentSpecifications
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 15
Electromechanical device …
(Controlled) electric power
Geometry Materials
Motion Force
•
Electro-mechanical energy converter•
Electromagnetism
intermediates energy conversion
•
Electric side: DC, AC, pulsed •
Mechanic side: linear, rotary motion
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 16
… mostly rotating electrical machine•
Topology selection and construction realization formulated as a design model for machine analysis and development
•
Design process from an idea to technical drawings for production
•
Machine components and parts–
Electromagnetically active and mechanical support such as housing and bearings
–
rotor with magnetization arrangement –
stator with magnetic core and electric windings
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 17
Exploring machine construction
•
Construction, calculation
and dimensioning
of electromechanical devices: mechanic, (di)electric, magnetic, thermal, etc …
•
Computer aided design –
good understanding on electromagnetic energy conversion is required
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 18
Variety of e-machines•
Machine
–
used to perform some useful work or to provide transportation
–
Electric machine is connected to electric power
•
Electric machine as Energy converter
–
Generation–
Transformation
–
Consumption
ELECTROMAGNETISM
G M
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 19
Motivation•
Employed by being creative –
engineering
challenges to think creatively•
Improve your power of understanding
and
power of imagination•
Actual trends –
integrability, manufacturability,
sustainability, …•
Design challenges
–
new technology, new
materials, computational power, …
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 20
Design process•
Component and system thinking–
Performance and controllability
–
Cost and manufacturability–
Loading and reliability
•
Dimensioning and modelling–
Multi-dimensional multi-physics
–
Supply, electronics, application, drive cycle, …
•
Optimizing–
Objective vs
design parameters
–
Visibility vs
sensitivity analysis
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 21
Design orientation•
Goal
formulation
–
Maximise
torque
o/a power product
–
Consider
the limits–
And keep
losses,
weight, cost
down
comparison comparison
verification of the model by simulation
verification of the model by theory
computer simulation theory
computed data theoretical prediction
modelling mathematical model of the device
measurement
experimental data
real device
ReliabilityMaterial engineering
Thermal design
ManufacturabilityProduction techniques
Tolerances
FunctionalityElectromagnetic design
Drive system
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 22
Setting up Design Parameterization― Geometry (W, H, proportions) ― Material properties (coil, core, ) ― Loads (duty, current, flow)
Geometric modeling (2D)― Draw cross-sections, model initialization, analytic/empiric models, realisation visibility
2D FE electromagnetics―
VAJA
j
B1
― Heating power q=J2 ρ
2D FE heat transfer― Temperature distribution
― qkcc
u
Parametric change― Rough sizing ― Operation point sweep ― Sensitivity study
Early estimation of machine performance vs manufacturability― Peak operation, visibility vs vulnerability, subjective analysis of production
Topology generation― Materials ability and formability ― Coils and conceivable ideas ―
2D FE fluid flow
―
Fuuuu
2
pt
― Cooling power q=uc
C-coalsCalculations completed?
V-Goals Visible solution?
Structure modeling (3D)― Draw complete component or a structure in the machine,
3D FE multiphysics― Voltage across terminals
cooling conditions along cooling surfaces
― etc
Theoretical specification of machine performance and production― Detailed construction vs functionality estimation, production methods, cost, tolerances
CAD for prototype― Technical drawings ― Engineering drawings
for production and assembling
R-GoalsRealizable solution?
Assembly modeling (2D and 3D)― Complete evaluation of the design vs detailed study on manufacturing issues
from simple towards more complex
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 23
… Analyze, Synthesize, Design …
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 24
Electrical machine in a nutshell•
Cause-effect, action-reaction
–
Understanding –
observation (physics) expression (maths) creation (innovation)
•
Classification –
based on “magnet origin”
(?)–
Pairs of magnets
–
Excitation vs
armature•
Understanding –
energy conversion
–
Thermodynamic arguments (conservation of energy)
–
Field analysis (Maxwell stress tensor)
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 25
Main parts•
Coil or winding
–
to produce variable
magnetic
flux•
Permanent magnet
–
to produce invariable
magnetic flux•
Soft magnetic core
–
to provide an easy path
for the flux in order to facilitate flux linkage or magnetic coupling between “sources”
and
“loads”
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 26
Introduction to magnetism•
Before we
control
or
construct
an electrical machine
we
play with
permanent magnets
•
The energy conversion between the electric and mechanic energy takes place in presence of the magnetic field
•
The traditional five senses of a human being exclude ability
to achieve
a direct response from magnetic field
that
intermediates the electromechanical energy conversion in an electrical machines
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 27
M M
F
F
Magnetic interaction vs attraction
M
M
F
M
M F
M M
M M
F
F
•
N40 NdFeB
magnets•
5x20x20 mm
•
Attraction
or repulsion ca 40 N
•
Shear
ca 27 N including
ca 7 N attraction/repulsion
•
Attraction
ca 8 N•
Shear
4 N attraction
3 N
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 28
Electromagnet vs PM•
Magnetic
field
around
current
carrying
coil
•
The principle of operation of any rotating electric motor is derived from Lorenz force.
•
Replace
PM by EM NI=Hl= ca 5kA
A-A+
I
A+
I
A+
I
M
F
M M
A+ A- I
A+ A- I
A+ A- I
A+ A- I
M M
F
F
F
F
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 29
Maxwell’s Stress Tensor•
magnetic
pressure
–
Magnetic
force on a ”surface”
–
t or σ
normal (n) and tangential (t) components
[N/m2]–
Calculated
from
gap flux density
B [T]
22
021
tnn BBt
0tn
tBBt
t
BBn
tn
Bt tt
α α
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 30
Force components•
Attraction between ferrous material and exciting magnetic fields due to permanent magnet(s) or coil(s) resulting in reluctance force/torque
•
Interaction between electromagnet(s) or/and permanent magnet(s) cause magnetic alignment
force/torque
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 31
Electromagnetic & magnetic forces•
Distance forces –
air-gap
•
Conductor
in magnetic field
–
Force due to current
– Flemming’s
left-hand rule
–
Induced voltage
due to motion –
Flemming’s
right-hand rule
•
Parts: field and armature
•
Arrangement of magnets–
Action & Reaction: share, attraction, repulsion
BI
F
B
Ev•
Types of forces and torques
–
Excitation, electrodynamical–
Reluctance
•
Energy=capacity for doing work=Forced
Motion W=Fx
two magnets
magnet and iron
W
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 32
How machines work•
Electrical machines exploit magnetic interaction
–
Two “magnets”
one in stator the other with the rotor–
displacement of these two magnets will create a torque
–
The magnets can be created directly or induced–
The bigger the torque the bigger the machine
–
Converts mechanical energy to electrical: generator, or vice versa –
motoring operation
•
No new topology–
The principles of machine design are more than 100 years old
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 33
Operation quadrants•
Q1: u>0, i>0, T>0, ω>0
•
Q2: bidirectional
voltage and speed, i>0, T>0
•
Q2: bidirectional
current and torque, u>0, ω>0
•
Q4: bidirectional
voltage, current, speed and torque
M
voltagespeed
currenttorque
G
GM
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 34
Rotating coil in magnetic field•
If the coil rotates in a magnetic field, the flux linking the coil will be an alternating
quantity
•
Connection via sliprings –
alternating voltage
•
Connection via commutator
–
“rectified”
voltage
B
eθ
B
e
θ
W
W
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 35
DC machine
221
222
00
BdAede
BlrBBlrBlue
av
•
Current carrying conductor in magnetic field
•
Magnetic field created by field coil or permanent magnets
•
As the armature rotates the 2 coil sides move in the magnetic field
S N B
iBilrdT
BBilrBlirFrT
av
221
222
0
BI
F
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 36
Types of machines•
Recall the names of electrical machines that you have heard or are familiar with!
•
According to excitation–
EM and PM
–
Reluctance and inductance•
According to supply
•
According to geometrical arrangement
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 37
Size of machines•
Torque
is proportional to size
and weight
•
Power is proportional to torque
and speed
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 38
Machine=Generator&Motor•
Can you figure
out
when
the ”animation” machine
operates as
a generator and when
as a motor?
ui
T
wP m
=Tw = iu=P e
Lund University / LTH / IEA / AR / EIEN20 / 2020-01-21 39
Home exercise1.
Find and download FEMM, start using it!
2.
Find and download Notepad++
, start using it!
3.
Experiment with femm1.
Learn to draw and define model
2.
Field around conductor and skin depth
3.
Forces between conductors and proximity effect
A-A+
I
A+
I