of electrical machines - iea.lth.se · l1 – introduction eien20 design of electrical machines,...

L1 – Introduction

EIEN20 Design of Electrical Machines, IEA, 2018 1

Industrial Electrical Engineering and AutomationLund University, Sweden

Design

Avo ReinapIndustrial Electrical Engineering and

Automation, LTH

of electrical machinesof electrical machines

Avo R Design of Electrical Machines 2

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Machine Design

Power of understanding• energy conversion• material properties• machine construction

Power of imagination• integration• production

Creativity

B

IF


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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

L1 – Introduction



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nElectrical machine design at Lund

• Material and production development

• Machine design and evaluation

• Direct air-cooled windings

• Unconventional actuators


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Need for electrical actuator

• Electrified traction drive• Integrated pump and fan drives• Wind generators• Mechatronics, robotics

• Maintenance

• As long we going to have electricity there is always an electrical machine around

Industrial Electrical Engineering and AutomationLund University, Sweden

L1: Introduction

Course overviewMachine construction overview


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Course (?)

• Design of electrical machines (EIEN20)

– Construction + production– Energy conversion

processes + analysis tools– Materials + properties

• From component towards application and system

L1 – Introduction



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nOther courses (@IEA)

• Power Electronics: Devices, Converters, Control and Applications (EIEN25)

• Hybrid Vehicle Drives (EIEN40)

• Wind Power Systems (EIEN10)

• Electric Power Systems (EIEN15)

• Mechatronics: Industrial Product Design (EIEN01)


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About the course

• Assessment– Approved design report

grants the grade 3. For higher grade a written exam is required.

• Learning process– 14x2 lectures (LP3)– 5 weekly home

assignments (LP3)– Course project (LP4)


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About the course

• 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

Borrowed from Ice Age I

Tools: own pc withResources: http://iea.lth.se/emk/


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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, …

L1 – Introduction



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nCourse goal

• objective of this course is to gain experience covering the overall design process: design, actual construction and testing of an electromagnetic device

• Understand the electromechanical design behind the classical electromagnetic devices


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Course Plan

• Preliminary course plan for lectures and project workshops

• Every second lecture an assignment is given that suppose to be solved and reported within 2 weeks

• Project assignments and groups are formed during LP3 and solved LP4

• Article and presentation is expected from the project


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Home assignments

• Introduction to computational techniques and software – optimization of a transformer

• Magnetic analysis and characteristics of transformer

• Thermal analysis of PMSM• Magnetic analysis and characteristics of PMSM• Machine types, models and characteristics


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Previous projects

L1 – Introduction



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nDesign Task 2018

• Traction machines• Components for ESS application• Topics related to Cooling integration

for electrical machines• Topics related to More Electric Aircraft

• One of the electrical machines that you study/control at power electronics

• Your own interest


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What is electrical machine, where do I find it?

• Machine– used to perform some

useful work or to provide transportation

• Energy converter– Generation– Transformation– Consumption

ELECTROMAGNETISM


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Electrical machine in a nutshell

• Cause-effect, action-reaction– Understanding – observation (physics) expression

(maths) creation (innovation)• Classification – based on “magnet origin” (?)

– Excitation vs armature• Understanding – energy conversion

– Thermodynamic arguments (conservation of energy)

– Field analysis (Maxwell stress tensor)


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Prior/Parallel knowledge

• Ohm’s Law• 1φ / 3φ• Cause of electro-

magnetic force (torque)• Magnetic flux vs.

electromotive force, electric current vs. magnetomotive force –Maxwell’s equations

• Power electronic control

L1 – Introduction



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nDeveloped knowledge

• Construction, calculation and dimensioning of electromechanical devices

• Computer aided design Good

understanding on

electromagnetic

gy conversionAvo R Design of Electrical Machines 22

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What is design for electromagnetics, where to start?

Reliability

Functionality

Manufacturability

Material engineering

Electromagnetic

design

Production

techniques

Thermal design

Cooling

techniques

Manufacturing tolerances

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


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Design process: from simple to more complex

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 pe rformance 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-GoalsVisible 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


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… Analyze, Synthesize, Design …

L1 – Introduction



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nActuator

(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


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Main parts

• Coil or winding – to produce variable magnetic flux

• Permanent magnet – to produce invariablemagnetic flux

• Soft magnetic core – to provide an easy pathfor the flux in order to facilitate flux linkage or magnetic coupling between “sources” and “loads”


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Introduction to magnetism

• Before we control or construct an electricalmachine 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


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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

L1 – Introduction



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nMaxwell’s Stress Tensor

• Magnetic force on a surface according to magnetic pressure

22

021

tnn BBt

0tn

tBBt

t

BBn

tn

Bt tt

α α


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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 force/torque


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Electromagnet vs PM

• Magnetic field aroundcurrent carrying coil

• The principle of operation of any rotating electric motor is derived from Lorenz force.

• Replace PM by EM NI=Hl= ca 5kA

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M

F

M M

A+ A- I

A+ A- I

A+ A- I

A+ A- I

M M

F

F

F

F


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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

• No new topology– The principles of machine design are more than 100 years old

L1 – Introduction



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nTypes of machines

• According to excitation– EM and PM– Reluctance and inductance

• According to supply• According to geometrical arrangement


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Control of machines

• Field oriented control– Maximise torque product– Consider the limits– And keep losses down

The goal for the design is quite the same as for the control


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Size of machines

• Torque is proportional to size and weight• Power is proportional to torque and speed


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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

L1 – Introduction



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nHome exercise

1. Find and download FEMM, start using it!

2. Find and download Notepad++ , start using it!

3. Experiment with femm1. Learn to draw and define

model2. Field around conductor and

skin depth3. Forces between conductors

and proximity effect

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of electrical machines - iea.lth.se · l1 – introduction eien20 design of electrical machines,...

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