SELECTION OF PROPULSION SYSTEMS FOR AUTOMOTIVE

1

SELECTION OF PROPULSION SYSTEMS FOR AUTOMOTIVE

APPLICATIONS

Pierre Duysinx

LTAS – Automotive Engineering Academic Year 2010-2011

2

Bibliography

„ R. Bosch. « Automotive Handbook ». 5th edition. 2002. Society of Automotive Engineers (SAE)

„ M. Ehsani Y. Gao, S Gay & A. Emadi. Modern Electric, Hybrid Electric, and Fuel Cell vehicles. Fundamentals, Theory and Design. CRC press. 2005.

„ G. Genta. Motor Vehicle Dynamics – Modeling and Simulation.

World Scientific Publishing. 2003.

„ T. Gillespie. « Fundamentals of vehicle Dynamics », 1992, Society of Automotive Engineers (SAE)

„ W.H. Hucho. « Aerodynamics of Road Vehicles ». 4th edition.

SAE International. 1998

„ J.Y. Wong. « Theory of Ground Vehicles ». John Wiley & sons.

1993 (2nd edition) 2001 (3rd edition).

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Outline

„

Specification of propulsion systems for automobiles

„

Ideal motorization

„

Other characteristics

„

Alternative thermal motorizations

„

Steam engines

„

Stirling engines

„

Gas turbines

„

Piston engines

4

Outline

„ Hybrid motorization

„ Definition

„ Layout

„ Architecture

„ Fuel cells

„ Definition

„ Fuel cell powered hybrid vehicles

„ Comparison

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Specification of propulsion systems

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Ideal characteristics of vehicle power plant

„ Remind first that the operating point of system is governed by the equilibrium between the power (forces) of the plant and the load.

„ The operating point is obtained by the intersection of the power (torque) curves of the plant and of the resistance loads

Resistance curves Plant curves

Equilibrium

Vitesse

7

Ideal characteristics of vehicle power plant

„ Ideal characteristics of power plant for vehicle propulsion: power curve close to constant powerfor any regime and so torque curve proportional to inverse of speed

„ It is the curve that maximizes the power

transmitted to the vehicle for any velocity

power

Speed / rotation speed

Torque

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Ideal characteristics of vehicle power plant

„ For low speed operation, the friction between the wheel and the road is limiting the transmitted force

„ Intrinsic limitation to the maximum

Adhesive

speed Torque

C A

= ω

max

x z

F = µ F

max max

e x z e

C = R F = µ F R

max

e z

C = R µF

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Ideal characteristics of vehicle power plant

„ Sensitivity of drivers

„ At low speed: we are sensitive to the acceleration:

„ Large acceleration capability

„ Large drawbar pull

„ Large traction force

„ Large gradeability capability

„ At high speed we are sensitive to the power of the motor to be able to overcome the resistance forces (mainly aerodynamics)

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Ideal characteristics of vehicle power plant

„ Motorizations close to ideal specification

„ Electric machines (DC motor with separately induction supply)

„ Steam engines (Rankine cycles)

„ Piston engines have less favorable characteristics:

„ Stall rotation speed

„ Non constant torque and power

„ Transmission necessary

„ Why are they dominant? Because there are also other criteria to be considered!

„ Weight to power ratio

„ Reasonable energy consumption

„ Low production cost

„ Easy to start…

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Ideal characteristics of vehicle power plant

„ More over, piston engines take benefit of a long story of innovation and improvements

„ Improvement of fuel consumption

„ Electronic fuel injection,

„ Lean burn techniques

„ Turbocharged engine and direct injections

„ Control of emissions in reducing pollutant emission (CO, NOx, HC, PM, etc.)

„ 3 ways catalytic reduction

„ DeNox and SCR

„ DFP

„ Etc.

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Ideal characteristics of vehicle power plant

„ Other criteria for vehicle power plants

„ Constant power

„ Weight to power ratio

„ Large speed operation range

„ Reasonable energy consumption

„ Control of pollutants emissions

„ Low production cost

„ Easy to start and operate

„ Serial production

„ Low maintenance

„ High reliability

„ Medium life time: 200.000 km about 2000 working hours

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Alternative power plants

„

Other internal combustion engine

„ Steam engines (Rankine cycle)

„ Gas turbines (Brayton cycle)

„ Stirling engine

„ Rotary piston engine (Wankel engine)

„

Other propulsion systems

„ Electric machines

„ Hydraulic and pneumatic motors

„ Hybrid propulsion systems

„ Fuel cells and electrochemical converters

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Alternative power plants

Vehicle propulsion

Combustion engines Electric motors

Internal combustion External combustion DC AC

Reciprocating engines Otto, Diesel,

Wankel, 2T / 4T

Stirling engine Steam engine (Rankine)

Continuous combustion Gas turbine Axial piston engines

Hybrids

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Steam engines

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Steam engines

Cugnot vehicle

Steam locomotive

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Steam engines

W

= W

+ Q

- Q

18

Steam engines

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Steam engines

„

Advantages:

„ Nearly ideal power / torque curves close to constant power

„ Is able to withstand temporary overcharge and high torque at low speed, so that there is no need for transmission

„ Large range of possible fuels

„ Emission of pollutants can be widely minimized because of external combustion

„

Drawbacks

„ Bad weight to power ratio

„ Bad volume to power ratio

„ Set up time is very long

„ Old solutions had a low efficiency (less than 20% in 180ies steam locomotive with exhaust of steam)

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Steam engines

1 – Piston 2 - Piston rod 3 - Crosshead bearing 4 - Connecting rod 5 – Crank 6 - Eccentric valve motion 7 – Flywheel 8 - Sliding valve 9 - Centrifugal governor.

http://en.wikipedia.org/wiki/Steam_engine

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Steam engines

Double piston stroke: uniflow steam engine

22

Steam engines

23

Stirling engine

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Stirling engine

„ Working principle of Stirling engine is based on a closed cycleand a working fluid (helium or hydrogen)that is heated and cooled alternatively

„ The Stirling engine is a external combustion engine

„ It is made of two iso thermal processes and two iso volume process.

„ The heat source calls for expansion a while cold source calls for compression

„ Both sources are separated by a regenerator.

„ The theoretical efficiency of Stirling cycle is equal to Carnot efficiency with the same difference of temperature.

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Stirling engine

Step I: the power piston (1) in lower position. The displacer piston (2) is moving in upper position. The working fluid is pushed in the cold chamber (3)

Step II: The power piston is compressing the cooled gas in isothermal process

Step III: The displacer piston moves downward and pushes the gas to the hot chamber (4) through regenerator and heater

Step IV: The Hot gas is expanding and is delivering some work to power piston. The displacer piston is moved downward

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Stirling engine

1. Power piston (dark grey) has compressed the gas, the displacer piston (light grey) has moved so that most of the gas is adjacent to the hot heat exchanger

2. The heated gas increases in pressure and pushes the power piston to the farthest limit of the power stroke

3. The displacer piston now moves, shunting the gas to the cold end of the cylinder.

4. The cooled gas is now compressed by the flywheel momentum. This takes less energy, since when it is cooled its pressure drops.

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Stirling engine

„ Advantages:

„ Very low specific pollutants emissions (external combustion)

„ Low noise generation

„ Several fuels can be used

„ Practical efficiency is equivalent to best Diesel engines

„ Drawbacks

„ In the state of the art: bad power to weight ratio

„ Mechanically complex

„ Low acceleration capabilities (better suited to stationary applications)

„ Too high manufacturing cost

„ Penalized by the large heat exchanger surface (air / air exchanger)

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Stirling engine

Practical layout of a Stirling engines with opposed pistons (Eshani et al. 2005)

Torque / speed curves of a Stirling engine (Eshani et al. 2005)

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Stirling engine

Performance and fuel consumption of a Stirling engine with 4 cylinder for vehicle traction (Eshani et al. 2005)

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Gas turbine

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Gas Turbine

„ Gas turbines are one the oldest type of internal combustion engines

„ Gas turbines are based on the Brayton cycle, which is an open cycle

„ They include an air compressor, a combustion chamber and a expansion turbine.

„ Turbines is actuated by the working fluid and convert the heat energy of the fluid into mechanical power. The shaft can be connected to a generator or connected to the wheels.

„ The combustion chamber of gas turbine can burn a wide variety of fuels: kerosene, gasoline, natural gas…

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Gas Turbine

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Gas Turbine

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Gas Turbine

„ Advantages:

„ High power to weight ratio

„ Ability to use a wide range of fuels

„ Low emissions of pollutants CO et HC

„ Good mechanical balancing because of rotary motion and low vibrations

„ Flat torque curves for double shaft solutions

„ Long periods between two maintenances

„ Disadvantages

„ Low efficiency outside design point

„ Bad fuel efficiency outside nominal design point

„ High cost (high temperature materials, heat exchangers)

„ Bad dynamic responses (rotation acceleration)

„ High rotation speed Îneed for a large reduction gear box (and so a weight penalty)

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Gas Turbine

Gas turbine with exchanger Eshani et al. 2005

Performance and fuel consumption of a gas turbine Konograd KKT. Eshani et al. 2005

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Gas Turbine

„ One repots several tentative applications of gas turbines to automobile

„ As soon as the WWII, Rover has been interested in gas turbines and has realized prototypes between 1950 and 1961.

„ In 1963, the Rover BRM 00 has participated to the La Mans 24 hours with Graham Hill et Richie Gunther and has finished in 8th position.

„ Later on gas turbines have been applied in heavy vehicles such as M1 Abraham armored vehicles.

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Gas Turbine

Turbine Car by Chrysler (1963)

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Piston engines

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History of ICE

„ 1700: Steam engine

„ 1860: Motor of Lenoir (efficiency η~5%)

„ 1862 Beau de Rochas defines the working principles of internal combustion engines

„ 1867: Motor of Otto & Langen: (η~11% and rotation <90 rpm)

„ 1876: Otto invents the 4-stroke engine 4 temps with spark ignition (η~14% and rotation < 160 rpm)

„ 1880: Two-stroke engine by Dugan

„ 1892: Diesel invents the 4-stroke diesel engine with compression ignition

„ 1957: Wankel invents the rotary piston engine

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Piston engines (Gasoline and Diesel)

One distinguishes several variants

„

Fuels:

„ Gasoline, diesel, LPG, Natural Gas, H2, bio-fuels…

„

Thermodynamic cycles:

„ Otto : spark ignition engine

„ Diesel : compression ignition engine

„

Fuel injection

„ direct or indirect

„ Turbocharged or atmospheric

„

Cycles

„ 2 strokes

„ 4 strokes

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Classification

„ The 4-stroke enginea performing the 4 steps in 4 strokes that is two

crankshafts rotation.

„ The 2-stroke engineis carrying out the four steps in two strokes, that is one crankshafts rotation.

„ The rotary engines: the rotating motion is replacing the alternating motion. The rotor rotation is realizing the four steps in one rotation

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Classification

SI engine

2 strokes 4 strokes

Carburetor Injection Carburetor Injection

CI engines

2 strokes 4 strokes

Indirect

injection Direct Injection Indirect

injection Direct Injection

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Classification

„ Atmospheric engine:

„ The air-fuel mixture or air is injected at atmospheric pressure during admission phase

„ The filling ratio is lower than 1

„ The power is limited by this coefficient

„ Supercharged / turbocharged engine

„ The air-fuel mixture / air is admitted with a overpressure

„ Compression increases the mass of admitted air so that one can inject more fuel and produce more power

„ Overpressure is realized by admitting the air through a compressor or a turbocharger

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4 stroke engines: gasoline

„ In 1862, Beau de Rochas developed a operation sequence that is still now the basis of any piston engine operations

„ The 4-stroke engine requires to 2 crankshaft revolutions to accomplish one thermodynamic cycles, which means 2 compression and expansion motions of the piston.

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4 stroke engines: gasoline

„ Stroke 1: Fuel-air mixture introduced into cylinder through intake valve

„ Stroke 2: Fuel-air mixture compressed

„ Stroke 3: Combustion (roughly constant volume) occurs and product gases expand doing work

„ Stroke 4: Product gases pushed out of the cylinder through the exhaust valve

Compression Stroke

Power

Stroke Exhaust

Stroke A

I R

Combustion Products Ignition

Intake Stroke FUEL

Fuel/Air Mixture

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4 stroke engines: gasoline

„ Advantages:

„ The spark ignition engine relies on a well-known principle, mature technology, and a well established technology

„ Good weight to power ratio

„ It is able to work while burning different fuels: gasoline, diesel, methanol, ethanol, natural gas, LPG, hydrogen…

„ It takes benefit of a large amount of technological developments to control the emissions of pollutants

„ Disadvantages:

„ Bad fuel economy and tedious emission control (HC, CO et NOx) when operated at part load and cold temperature conditions

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4 stroke engines: diesel

„ The Four stroke Compression Ignition (CI) Engine is generally denoted as the Diesel engine

„ The cycle is similar to Otto cycle albeit that it requires a high compression ratio and a low dilution (air fuel) ratio.

„ Air is admitted in the chamber and then compressed. The temperature rises the ignition point and then the fuel is injected at high pressure. It can inflame spontaneously.

„ There is no need for a spark and so stocheometric air fuel ration is not necessary.

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4 stroke engines: diesel

„ Stroke 1: Air is introduced into cylinder through intake valve

„ Stroke 2: Air is compressed

„ Stroke 3: Combustion (roughly constant pressure) occurs and product gases expand doing work

„ Stroke 4: Product gases pushed out of the cylinder through the exhaust valve

Compression Stroke

Power Stroke

Exhaust Stroke A

I R

Combustion Products

Intake Stroke

Air

Fuel Injector

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4 stroke engines: diesel

„ Advantages:

„ Higher efficiency because of higher compression ratio

„ Largely developed and technological availability

„ Low CO and HC emissions

„ Disadvantages:

„ Larger PM and NOx emissions ratios

„ Heavier and larger than gasoline engines, but still high compared to other technologies

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2-stroke engines

„ Dugald Clerk has invented the 2-stroke engine in 1878 in order to increase the power to weight ratio for a equal volume.

„ The 2-stroke engines is also simpler with regards to valve system

„ The 2-stroke principle is applicable to both spark ignition engine and compression ignition engine. It is however more usual with spark ignition engines.

„ The 2-stroke engine involves two strokes and the cycle is carried out during one single crankshaft revolution.

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2-stroke engines

Intake(“Scavenging”)

Compression Ignition Exhaust Expansion

Fuel-air-oil mixture Fuel-air-oil mixture compressed

Crank shaft Check valve

Exhaust port

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2-stroke engines

„ Stroke 1: Fuel-air mixture is introduced into the cylinder and is then compressed, combustion initiated at the end of the stroke

„ Stroke 2: Combustion products expand doing work and then exhausted

„ * Power delivered to the crankshaft on every revolution

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2-stroke engines

„ Compared to 4-stroke engines, 2-stroke engines have

„ Power to weight ratio is higher than the four stroke engine since there is one power stroke per crank shaft revolution.

„ Simple valve design

„ A lower fabrication cost

„ A lower weight

„ However several drawbacks:

„ Incomplete scavenging or to much scavenging

„ Higher emission rates: emission of HC, PM, CO is quite badly controlled (even though mitigated for CI 2-stroke engine)

„ Burns oil mixed in with the fuel

„ Exhaust gas treatment is less developed than 4-stroke engines

„ Most often used for small engine applications such as lawn mowers, marine outboard engines, motorcycles….

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Piston engines characteristics

„ Good combustion properties (and so the maximum torque) are obtained for a medium (design) rotation speed.

„ For increasing rotation speed, the admission pressure drop and the engine frictions are increasing and the brake mean effective (and the torque) pressure is dropping.

„ Power = torque * speed is still increasing till the torque drops is so high than power is falling as well.

„ A low regimes, the dilution is high and the combustion is deteriorated, while heat transfer to piston and walls is becoming more important. It comes that the mean effective pressure and the torque is also reduced.

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Piston engines characteristics

Gillespie, Fig. 2.1

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Piston engines characteristics: fuel consumption

Wong. Fig. 3.41 et 3.42

Gasoline engine

Diesel engine

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Piston engines characteristics: emission rates

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Wankel Rotary Engines

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Wankel rotary engines

„ In 1951, Felix Wankel began

development of the rotary piston engine at NSU.

„ The rotary engine uses a rotary design to convert pressure into a rotating motion instead of using reciprocating pistons.

„ Its four-stroke cycle takes place in a space between the inside of an oval-like epitrochoid-shaped housing and a rotor that is similar in shape to a Reuleaux triangle.

60

Wankel rotary engines

E: Pinion – L:

Eccentric

61

Wankel rotary engines

„ Combining a suitable layout of the inlet, outlet and ignition devices, the volume variation of the each chamber works out the 4 strokes of the Otto cycle in one revolution of rotor.

„ As the rotor makes 3 chambers, one sees a cycle every 1/3 of the rotor revolution

„ The gear ratio between the crankshaft pinion and interior gears of the eccentric provides a 1:3 reduction ratio so that one sees a cycle at each revolution of the crankshaft

62

Wankel rotary engines

63

Wankel rotary engines

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Wankel rotary engines

„ Advantages

„ Perfect balancing of rotating mass that allows high rotation speeds

„ Favorable (linear) torque curve

„ Compact and simple design

„ Lightweight

„ Can be operated with various fuels such as H₂

„ Disadvantages

„ Lower efficiency than piston engines (lower compression ratio)

„ Slightly higher specific emissions (HC, NOx, CO)

„ The combustion chamber does not allow Compression ignition (Diesel) cycles

„ Manufacturing cost is more important

65

Wankel rotary engines

„ Wankel rotary engines were used first in NSU vehicles

„ After the NSU collapse, Mazda has bought the rights for the patents of the rotary engines

„ Future applications of rotary engines is related to its ability to be operated with alternative gaseous fuels such as H₂

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Electric traction

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Electric cars

„ Electric cars were very dominant at the turn of the 20th century but were substituted by ICE engine in the period from 105 to 1915

„ Revival interest for electric cars at every petrol or energy crisis

„ But up to now, electric cars have always been commercial failure

„ At the turn of the 21th century, electric propulsion systems are coming back at the front stage

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Electric propulsion

„ Advantages:

„ Zero direct emission

„ Low noise emissions

„ Regenerative braking

„ High torque at low speed

„ Good driving comfort Æurban application

„ Simple mechanical transmission (generally no gear box, no clutch), speed and torque regulation,

„ Perfect solution if external power supply (catenaries)

„ Disadvantages:

„ Batteries: cost, extra-weight, life time

„ Charging time (~6 hours)

„ Limitation of range (200 km)

Bolloré BlueCar

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Electric propulsion

Electric drivetrain are basically composed of four components:

1. The electrical power source: battery if energy is on board or catenaries system to connect to an external source as electric cables or rail

2. Power electronics to regulate the power, the speed, the torque

3. The electric machine that can operate as a motor or a generator

4. A simple mechanical transmission to communicate the mechanical power to the wheels

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Electric propulsion

„ Electric machines

„ DC shunt, series, or separately excited

„ AC asynchronous 1 or 3-phase, synchronous machine with PM

„ Switched reluctance motors

„ Power electronics

„ Chopper

„ DC / DC chopper

„ Inverter

„ Batteries:

„ Lead acid

„ Nickel-Cadmium

„ Ni – MH metal hydrides

„ Li ions / Li polymers

„ Supercaps, flywheels

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Families of electric motors

72

DC electric motors

Working principal of a DC motor

73

DC electric motors

Types of DC machines and torque curves

74

Power electronics for DC machine

Working principle of a chopper

75

AC asynchronous electric motors

Working principle of AC asynchronous motors

76

3-phase AC asynchronous motors

77

3-phase AC asynchronous motors

Torque-speed AC asynchronous motors

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Power electronics for 3-phase AC machines

Working principle of an inverter

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Traction electric machines

DC MOTORS

„ Serial or separated excitation

„ Price still high (-)

„ Reliability and control (+)

„ Maintenance (brush) (-),

„ Weight (-)

„ Max speed (-)

„ Efficiency ~80% (-)

„ Control by chopper with PWM command

AC MOTORS

„ Asynchronous machines

„ High maximum speed

„ Low maintenance, high reliability

„ Weight

„ Good efficiency (~95%)

„ Synchronous machines

„ Maintenance, efficiency , reliability (+)

„ Expensive (-),max speed lower than AC async(-)

„ Inverter with vector command (f,I,V)

80

Batteries

„ Different kinds

„ Lead acid: known since 1900, industrial maturity

„ Ni-Cd : known from 19030ies, industrial maturity

„ Na Ni Cl (Zebra): since 1980ies. Small series

„ NiMH: Since 190ies. Industrial standard in automotive

„ Li-Ions: Known from mid 1990ies. Moving to mass production.

„ Performance criteria

„ Specific energy (W.h/kg)

„ Specific power (W/kg)

„ Charge – discharge efficiency

„ Life time

„ Specific cost

81

Batteries performances

0,734 0,781

1,159 0,508

0,339 Specific cost [€/kW.h]

500 1200

1200 1200

600 Life cycles [cycles]

85 85

80 65

60 Charge – discharge

efficiency [%]

294 148

118 79

90 Specific power [W/kg]

105 74

62 38

17 Useful specific energy

[W.h/kg]

Li-Ions Zebra

Ni-MH Ni-Cd

Lead-Ac Batteries

82

Batteries challenge

83

Batteries challenge

84 2100

1420 Specific energy at wheel

[W.h/kg]

80 18

12 Average efficiency while

driving [%]

105 11.667

11.833 Specific energy [W.h/kg]

Li-Ions Diesel

Gasoline Fuel / energy systems

Gap 200!

84

Supercapacitor

„

Supercapacitors:

„ Absord / release energy much faster: 100-1000 times: (Power density~ 10 kW/kg)

„ Lower energy density ( Energy density < 10 kWh/kg)

„ Higher charge / discharge current : 1000 A

„ Longer life time: > 100.000 charge discharge

„ Better recycling performances

„ Supercapacitors are distinguished from other class of devices for storing electrical energy such batteries.

85

Hybrid propulsion systems

86

Hybrid propulsion powertrains

„ The hybrid powertrains combines two kinds of propulsion systems and their related energy storages.

„ Generally the hybrid electric powertrains are the most famous.

They combines typically an ICE engine and an electric motor and a electric energy storage system

„ The goal of hybridization is to combine the advantages of the two basic systems (e.g. zero emission of EV and range of ICE) and to mitigate their drawbacks.

„ There are two major families of layout to assemble the two types of propulsion systems.

87

Hybrid propulsion powertrains

Serial hybrid Parallel hybrid

88

Parallel hybrid vehicles

„ The vehicle is equipped with a double propulsion system (electric + ICE) both connected to the wheels.

„ The vehicle is preserving its usual performances: range, acceleration, cruse speed….

„ The electric machines have a sufficient power to propel the car on a significant distance in pure electric modeor in combination with the ICE.

„ To deliver peak powers when needed, both propulsion systems can be operated simultaneously

„ There are several variant of the parallel layout

„ Hybridization index: T_p= P_el/(P_el+ P_th)

89

Hybrid series vehicle

„ The electric machines is the single propulsion system to be connected to the wheels. The thermal engine is used in an optimized way to power the generator and supply the electric motor and / or the energy storage system.

„ In urban driving, the battery is able to supply the motors alone for short travels in pure electric mode with zero emissions

„ On highway travel and long distance driving cycles, the ICE is powering the generator to recharge the battery or supply the motor.

„ Hybridization index in series: T_s= P_th/P_el(generally between 40 and 80% Æ downsizing of ICE)

„ Extension possible to fuel cell vehiclesto substitute the ICE as prime mover

90

The complex hybrid vehicles

Toyota Prius II

91

Hybrid hydraulic vehicle

New reversible hydraulic motor /pump: Low drag, high efficiency, fluid=water ÎParker P2 or P3 series

Hydraulic accumulators (HP) / Reservoir (LP): high efficiency (95%)

En.: 0,63 Wh/kg Power ~ 90 kW/kg ÎHydac

92

Fuel cells

93

Fuel cell

H₂Æ2H⁺+ 2e^-

Oxygen (air) Electrolyte

Anode Cathode

e-

2H⁺+2e^-+ ½ O₂ ÆH₂O H⁺

Water Hydrogen

94

Fuel cell

„

Fuel Cell principle: direct electrochemical (oxydo- reduction) converter of Hydrogen fuel into electricity

„

Advantages:

„ No emission of pollutants

„ Using other fuels (ex methanol) is possible via reforming process

„ High conversion efficiency (theoretical 90% - practical 55%)

„

Drawbacks

„ Not mature technology

„ Thermal control is difficult to carry out

„ Lower power to weight compared to ICE

95

Fuel cell powered vehicle layout

Control electronics H

2

F.C. ^Chopper

Electric motor

Chain transmission

H2

PAC Power electronics (chopper)

Electric motor

96

Hybrid vehicle powered with a fuel cell

H₂

DC

Fuel DC

Cell

Li-Ion Batter y

Chopper

Electric motor

Transmission (chain) Tension PAC

Tension batterie Tension moteur Tension Moteur

97

Hybrid vehicle powered with a fuel cell

Toyota FCH4

Battery

M/G Fuel cells

Wheels Node

Tank

Chemical

Electrical

Mechanical

98

Comparison of propulsion systems

99

Comparison of propulsion systems

100

Comparison of propulsion systems

„Torque curve is favourable to electric motors and steam engines

„Torque curve of gas turbines is completely is very bad with regards to the application