1. Introduction - Lunds tekniska högskola · L1: Introduction • Terminology – Design –...

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

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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