Vehicle Propulsion Systems · Switched Reluctance Motor •Rotor seeks position that allows minimal reluctance for the electric field. Source: 56. Switched Reluctance Motor = AC Synchronous

Vehicle Propulsion Systems

Lecture 6

Electric & Hybrid Electric Propulsion Systems Part I

1

Team

• Chris [email protected] K37.2, +41 44 63 2 2466

• Philipp [email protected]+41 78 633 5876

• Andyn [email protected]+41 58 765 4441

• Andreas [email protected] K39, +41 44 63 2 8066

Planning of Lectures and Exercises:Week Lecture, Friday, 8:15-10:00, ML F34 Book

chp.Exercise , Friday, 12:00-13:30, CHN E46

38, 20.09.2019 Introduction, goals, overview propulsion systems and options

1 Introduction

39, 27.09.2019 Fuel consumption prediction I 2 Exercise I, Milestone 1

40, 04.10.2019 Fuel consumption prediction II 2 Exercise I, Presentation

41, 11.10.2019 IC engine propulsion systems I 3 Exercise II, Milestone 1

42, 18.10.2019 IC engine propulsion systems II 3 Exercise II, Milestone 2

43, 25.10.2019 Hybrid electric propulsion systems I 4 Exercise II, Presentation

44, 01.11.2019 Hybrid electric propulsion systems II 4 Exercise III, Milestone 1

45, 08.11.2019 Hybrid electric propulsion systems III 4 Exercise III, Milestone 2

46, 15.11.2019 Non-electric hybrid propulsion systems 5 Exercise III, Presentation

47, 22.11.2019 Supervisory Control Algorithms I 7 Exercise IV, Milestone 1

48, 29.11.2019 Supervisory Control Algorithms II 7 Exercise IV, Milestone 2

49, 06.12.2019 Supervisory Control Algorithms III 7 Exercise IV, Milestone 3

50, 13.12.2019 Case Study Exercise IV, Presentation

51, 20.12.2019 Tutorial Lecture, Q & A

Today

• “Quasi Steady-State” Modeling

• Electric & Hybrid-Electric Propulsion Systems

• Electric Motors

13

“Quasi Steady-State” Modeling

a) Model as quasi steady-state

b) Model as dynamic

c) Model as constant

QSS = controlled variable perfectly follows reference value, no transient dynamic phenomena…

14

Vehicle Example

1. Assume Vehicle = 𝑷

2. Assume a perfect driver 𝑪 = 𝑷−1

Then: 𝑣 = 𝑣𝑟𝑒𝑓 ∀ 𝑡

Drivingmission

Driver Engine Vehiclekinematics

Integration 𝑣𝑎𝑇ሶ𝑚𝑓𝑣𝑟𝑒𝑓

𝑷𝑷−𝟏

15

Vehicle Example

In fact this is the same as reversing causality

Velocity profile → acceleration → torque →…

The dynamics of the vehicle are still relevant and are not neglected!

In the VPS-Book this approach will be referred to as QSS-modeling.

Engine+GB

Vehiclekinematics

Differentiation 𝑣𝑟𝑒𝑓𝑎𝑇ሶ𝑚𝑓

𝛾

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Model Types

• Phenomenological

– Based on physical principle

• Heuristic

– Based on observations

• Tabulated

– Based on measurements

Degree of understandingand capability of extrapolation

White-box models

Black-box models

17

Today

• “Quasi Steady-State” Modeling

• Electric & Hybrid-Electric Propulsion Systems

– Motivation

– Topologies and classification

– Energy management

– Optimization of hybrid powertrains

• Electric Motors

18

Why bother?

• Waste of braking energy

• Part-load problem

• Pollutant and CO2 emissions19

Part-load problem

Best efficiency

Daily driving

Strong acceleration

>200 km/h

20

Hybrid powertrain

Hybrid powertrain = more than one “prime mover”

21

Hybrid powertrain

• Recuperation

• Idling losses

• Operating-point shifting

• Downsizing

𝑝𝑒 =𝑇𝑒𝑁𝜋

𝑉𝑑22

Today

• “Quasi Steady-State” Modeling

• Electric & Hybrid-Electric Propulsion Systems

– Motivation

– Topologies and classification

– Energy management

– Optimization of hybrid powertrains

• Electric Motors

24

Hybrid Powertrain Topologies

1. Parallel

2. Series

3. Combined

25

Classification

𝐷𝑜𝐻 =𝑃el,max

𝑃el,max + 𝑃th,max

(e.g. Prius)

can be charged from electric grid

f

(e.g. Volt)

(e.g. BMW i8)

(e.g. Tesla)

26

Other hybrid configurations

• Electric

– Battery

– Supercapacitor

• Mechanic

– Flywheel

• Hydraulic

• Pneumatic

• Fuel Cell

27

Today

• “Quasi Steady-State” Modeling

• Electric & Hybrid-Electric Propulsion Systems

– Motivation

– Topologies and classification

– Energy management

– Optimization of hybrid powertrains

• Electric Motors

28

Energy flow

• Possible “modes” in a parallel hybrid

𝑢 =𝑇em𝑇req

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Energy flow

• Possible “modes” in a serial hybrid 𝑢 =𝑃batt𝑃req

30

Energy management

• Hybrids need an “energy management”– Control system that decides which mode to use

– regenerative braking, operating point shifting and engine on/off.

• EMS has a huge influence on fuel economy!

Drivingmission

Driver 𝑎𝑟𝑒𝑓𝑣𝑟𝑒𝑓 Energymanagement

𝑇𝑒 , 𝑇𝑚

𝛾, 𝑃𝑏

𝑣

𝑎

31

Today

• “Quasi Steady-State” Modeling

• Electric & Hybrid-Electric Propulsion Systems

– Motivation

– Topologies and classification

– Energy management

– Optimization of hybrid powertrains

• Electric Motors

32

Optimization

• Topology

• Component sizing

• Energy management

• Chicken & Egg:Optimal

topology & components

Optimal Energy

management

Driving Mission

?System designer needs expert knowledge in bothcontrol engineering and optimization!

33

Today

• “Quasi Steady-State” Modeling

• Electric & Hybrid-Electric Propulsion Systems

• Electric Motors

– Types and Working principles

– Modeling

– DC-Converter / Power-Inverter

43

Conductor in Magnetic Field

Conductor produces a cylindrical magnetic field.

Two interacting magnetic fields produce a force.

Source: www.one-school.net44

Left Hand Rule

Source: en.wikipedia.org45

DC Motor

Source: hyperphysics.phy-astr.gsu.edu46

DC Motor with Permanent Magnet

Common construction

47

DC Motor with Permanent Magnet

Brush

Stator & Rotor

AC-DC converter

Reduction gear

Fan

Collector

Source: deviantart.com 48

How to get rid of the brush & collector?

Turn the whole thing inside out:

• Windings on stator

• Magnets on rotor

49

AC Synchronous with PM

By applying phased current, a rotating magnetic field can be generated.

Interacting magnetic fields produce force.

Source: http://www.homofaciens.com/technics-electric-motors-synchronous-motor_ge_navion.htm50

AC Synchronous with PM

Behavior is similar to brushed DC motors,

→ “brushless DC motor”

Torque can be produced at synchronous speed, due to permanent magnet.

Source: http://www.homofaciens.com/technics-electric-motors-synchronous-motor_ge_navion.htm51

AC Synchronous Motor with PM

• Example: CD-Drive

Source: www.electronics-lab.com52

AC Synchronous Motor with PM

• Example: Traction Motors for Tram and Railway

280kW synchronous motor

53

How to get rid of the magnets?

Don’t use magnets:

• Use ferromagnetic material instead

54

Magnetic Reluctance

• A magnetic field follows the way of minimal magnetic reluctance.

• Ferromagnetic materials have low magnetic reluctance.

Source: www.rfcafe.com

55

Switched Reluctance Motor

• Rotor seeks position that allows minimal reluctance for the electric field.

Source: www.ibiblio.org

56

Switched Reluctance Motor

= AC Synchronous Machine without PM

Torque can be produced at synchronous speed, due to reluctance effect.

Source: machinedesign.com57

Drawbacks:

- Torque ripples

- Lower power density

Use Induction!

58

Today

• “Quasi Steady-State” Modeling

• Electric & Hybrid-Electric Propulsion Systems

• Electric Motors

– Types and Working principles

– Modeling

– DC-Converter / Power-Inverter

59

Electromagnetic Induction

= change in magnetic flux causes an electric field

For induction motors:1. Change in flux causes

electric field

2. Electric field causes current

3. Current causes force

Source: https://de.wikipedia.org/wiki/Elektromagnetische_Induktion60

Conductor = Squirrel Cage

1. Difference in speed causes change in magnetic flux,

2. which causes induced voltage (electromotive force, emf),

3. which causes induced current,

4. which, together with magnetic field causes force.

Δ𝑈

𝐼

𝐵𝐹

Source: what-when-how.com

𝜔𝑟

𝜔𝑠

61

AC Asynchronous

This also works when squirrel cage is a “coke can”

→ “Coca-Cola motor”https://www.youtube.com/watch?v=cIf9iPskgJs

Source: www.yaskawa.com62

AC Asynchronous

This type of motor can only produce torque when the speed of the stator magnetic field is different from the one of the rotor

→ “asynchronous motor”

→ “induction motor”

63

AC Asynchronous

Good:

• Squirrel cage does not need physical connection to outside

• No precious metals needed for permanent magnets

Drawback:

• Power density not as high as with permanent magnets

• Control of machine is difficult

64

Classification

√

√

√

√

65