환경 친화적 자동차: 신형 파워트레인

환경 친화적 자동차 : :

신형 파워트레인

E-mail: hogijung@hanyang.ac.kr

http://web.yonsei.ac.kr/hgjung



• Load power is decomposed into steady and dynamic components.

IC engine, fuel cell @ optimum operating region

Electric motor

• The total energy output from the dynamic powertrain will be zero in a whole driving cycle.

• This implies that the energy source of the dynamic powertrain does not lose energy capacity at the end of the driving cycle. It functions only as a power damper .



Series Hybrid Drivetrain



Series Hybrid Drivetrain

Advantages

1) Mechanical decoupling between the IC engine and the driven wheels allows the IC engine operating at its very narrow optimal region.

2) Single torque source (electric motor) to the driven wheels simplifies the speed control (similar as throttle control by accelerator pedal)

3) Nearly ideal torque-speed characteristic of electric motor makes multigear transmission unnecessary

4) Simple structure and drivetrain control and easy packaging (the engine/generator, batteries, and the traction motor are connected by only electrical cables).

Disadvantages

1) Twice the energy form conversions (mechanical from engine to electric through generator and then to mechanical again through traction motor) cause more energy losses

2) Two electric machines are needed (electric generator and traction motor)

3) A big traction motor since it is the only torque source of the driven wheels.



Usually used in heavy vehicles, such as heavy commercial vehicles, military vehicles, buses, and even locomotives. Ex) Ebus, Electric Vehicles International, ISE Research--Thunder-Volt, etc.



Parallel Hybrid Drivetrain



Parallel Hybrid Drivetrain

Advantages

1) Both engine and electric motor directly supply torques to the driven wheels and no energy form conversion occurs, thus energy loss is less .

2) Compactness due to no need of the generator and smaller traction motor.

Disadvantages

1) the mechanical coupling between the engine and the driven wheels, thus the engine operating points cannot be fixed in a narrow speed region.

2) the complex structure and control.



Usually used by small vehicles. Ex) Honda Insight, Honda Civic, Ford Escape, etc.



Series-Parallel Hybrid Drivetrain

2. Ring: wheel

3. Planet: engine

1. Sun: generator/motor

Decoupling the engine speed from the wheel speed.

At a given vehicle speed (

ω

( ω

2

), the generator/motor speed

1

) can be adjusted to adjust the engine speed ( ω

3

).




Generator/Motor

1) Negative speed (opposite direction versus the torque)

 generating mode

Drivetrain

Engine power

2) Positive speed

 motoring mode

Generator

Engine power

Motor

Drivetrain



The engine speed can be adjusted to its optimal region by controlling the generator/motor speed.




Advantages

1) It combines the advantages of series and parallel drivetrains.

Disadvantages

1) It makes the drivetrain somewhat complicated (additional electric machine and a planetary unit).



Ex) Toyota Prius



Ideal Torque-Speed Profile for Traction

The ideal torque (power)-speed profile for traction application is the constant power in all the speed ranges . A well-controlled electric motor drive has the torque-speed profile close to the ideal one as below.



Candidates of Electric Motor Drives for Traction

- Permanent magnet brushless DC (BLDC) motor

- Induction motor (IM)

- Switched reluctance motor (SRM)



Physical Basis: Lorentz force

In physics, the Lorentz force is the force on a point charge due to electromagnetic fields . It is given by the following equation in terms of the electric and magnetic fields:

The magnetic force component of the Lorentz force manifests itself as the force that acts on a current-carrying wire in a magnetic field . In that context, it is also called the Laplace force .

http://en.wikipedia.org/wiki/Laplace_force#Force_on_a_current-carrying_wire



Physical Basis: Fleming’s left hand rule for motors

The bottom line is that Fleming's left hand rule is used for electric motors, while Fleming's right hand rule is used for electric generators.

Fleming's left hand rule



Electric motor

Fleming's right hand rule



Generator http://en.wikipedia.org/wiki/Fleming's_left_hand_rule_for_motors http://www.magnet.fsu.edu/education/tutorials/java/handrules/index.html



Physical Basis: Magnetic Line of Force

Right hand grip rule: Prediction of direction of field ( B ), given that the current I flows in the direction of the thumb. http://en.wikipedia.org/wiki/Right-hand_rule

The interaction of the two magnetic fields (the magnetic field of the current-carrying wire and the magnetic field of the permanent magnet ) produces a resultant field known as catapult field as shown in the figure above.

The non-uniform field produces the catapult force from the stronger field to the weaker field .

http://www.one-school.net/Malaysia/UniversityandCollege/SPM/revisioncard/physics/electromagnetism/catapultforce.html

Since the magnetic field lines of force are no longer straight lines, but curved to run under the electrical conductor , they are under tension (like stretched elastic bands) , with energy stored up in the magnetic field.

http://en.wikipedia.org/wiki/Fleming's_left_hand_rule_for_motors



Direct Current (DC) Motor

Stator

Rotor

If a current carrying coil is placed in a magnetic field, a pair of forces will be produced on the coil. This is due to the interaction of the magnetic field of the permanent magnet and the magnetic filed of the current carrying coil.

http://www.oneschool.net/Malaysia/UniversityandCollege/SPM/revisioncard/physics/electromagnetism/catapultforce.html



Commutator

Direct Current Electric Motor http://youtu.be/Xi7o8cMPI0E

Electric motor converts electrical energy to kinetic energy . It consist a rectangular coil of wire placed between 2 permanent magnets. The coil are soldered to a copper split ring known as commutator . 2 carbon brushes are held against the commutator.

The function of the commutator is to change the direction of the current in the coil and hence change the direction of the couple (the 2 forces in opposite direction) in every half revolution. This is to make sure that the coil can rotate continuously .

http://www.oneschool.net/Malaysia/UniversityandCollege/SPM/revisioncard/physics/electromagnetism/catapultforce.html



Wound stators

: shunt : series : compound f = field coil

DC motors are commonly constructed with wound rotors and either wound or permanent magnet stators.

The field coils have traditionally existed in four basic formats: separately-excited (sepex), series-wound, shunt-wound, and a combination of the latter two; compound-wound. http://en.wikipedia.org/wiki/Permanent-magnet_electric_motor#Permanent-magnet_motors



http://ccie-accreditation.org/anonymizer-wind-i nrunner-bldc/ http://dev.emcelettronica.com/you-use-bldc-motor-youshould-understand-how-it-works-brushless-dc-motorsroll



http://www.open-sport.org/Buzz/assets_c/2011/05/4-pole-bldc-motor021804-5.html



http://www.bavariadirect.co.za/models/images/CD_Star_diagram.gif



A 3-phase power supply provides a rotating magnetic field in an induction motor.

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

A symmetric rotating magnetic field can be produced with as few as three coils. The three coils will have to be driven by a symmetric 3-phase AC sine current system , thus each phase will be shifted 120 degrees in phase from the others. http://en.wikipedia.org/wiki/Rotating_magnetic_field

Sine wave current in each of the coils produces sine varying magnetic field on the rotation axis. Magnetic fields add as vectors.

Vector sum of the magnetic field vectors of the stator coils produces a single rotating vector of resulting rotating magnetic field.



Physical Basis: Faraday’s Law of Induction

Faraday's law of induction is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators. The law states that:

"The induced electromotive force (EMF) in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit.”

Or alternatively:

“The EMF generated is proportional to the rate of change of the magnetic flux.” http://en.wikipedia.org/wiki/Faraday%27s_law_of_induction



Physical Basis: Lenz’s Law

Lenz's law is a common way of understanding how electromagnetic circuits must always obey Newton's third law and The Law of Conservation of Energy. Lenz's law is named after Heinrich Lenz, and it says:

"An induced current is always in such a direction as to oppose the motion or change causing it“ http://en.wikipedia.org/wiki/Lenz%27s_law http://www.britannica.com/EBchecked/media/135

6/Demonstration-of-Faradays-and-Lenzs-laws



Physical Basis: Lenz’s Law

Eddy Current Tubes http://youtu.be/nrw-i5Ku0mI

MRI MAGIC http://youtu.be/fxC-AEC0ROk



Principle of Operation

The induction motor does not have any permanent magnets on the rotor; instead, a current is induced in the rotor. To achieve this, stator windings are arranged around the rotor so that when energised with a polyphase supply they create a rotating magnetic field pattern which sweeps past the rotor. This changing magnetic field pattern induces current in the rotor conductors. These currents interact with the rotating magnetic field created by the stator and in effect causes a rotational motion on the rotor.

AC Induction Motor http://youtu.be/UsT-qWAzTHg



Structure

The most common rotor is a squirrel-cage rotor. It is made up of bars of either solid copper

(most common) or aluminum that span the length of the rotor, and those solid copper or aluminium strips can be shorted or connected by a ring or some times not, i.e. the rotor can be closed or semiclosed type. The rotor bars in squirrel-cage induction motors are not straight, but have some skew to reduce noise and harmonics.

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

Animation of a squirrel-cage AC motor

Squirrel Cage Motors.MPG

http://youtu.be/3MbP4t920Is



Physical Basis: Magnetic Reluctance

Magnetic reluctance , or magnetic resistance , is a concept used in the analysis of magnetic circuits. It is analogous to resistance in an electrical circuit, but rather than dissipating magnetic energy it stores magnetic energy. In likeness to the way an electric field causes an electric current to follow the path of least resistance, a magnetic field causes magnetic flux to follow the path of least magnetic reluctance.

Variation of reluctance is the principle behind the reluctance motor (or the variable reluctance generator) and the Alexanderson alternator. Another way of saying this is that the reluctance forces strive for a maximally aligned magnetic circuit and a minimal air gap distance.

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



Structure

The stator consists of multiple salient (i.e., projecting) electromagnet poles, similar to a wound field brushed DC motor.

The rotor consists of soft magnetic material, such as laminated silicon steel , which has multiple projections acting as salient magnetic poles through magnetic reluctance.

The number of rotor poles is typically less than the number of stator poles , which minimizes torque ripple and prevents the poles from all aligning simultaneously—a position which can not generate torque.

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

Cross-section of switched reluctance machine with 6 stator and 4 rotor poles. Notice the concentrated windings on the stator poles.




When a rotor pole is equidistant from the two adjacent stator poles, the rotor pole is said to be in the "fully unaligned position". This is the position of maximum magnetic reluctance for the rotor pole.

In the "aligned position", two (or more) rotor poles are fully aligned with two (or more) stator poles, (which means the rotor poles completely face the stator poles) and is a position of minimum reluctance .

When a stator pole is energized, the rotor torque is in the direction that will reduce reluctance . Thus the nearest rotor pole is pulled from the unaligned position into alignment with the stator field (a position of less reluctance).




In order to sustain rotation, the stator field must rotate in advance of the rotor poles , thus constantly "pulling" the rotor along.

Some motor variants will run on 3-phase AC power .

Most modern designs are of the switched reluctance type, because electronic commutation gives significant control advantages for motor starting, speed control, and smooth operation

(low torque ripple).

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



Simulation of a Switched Reluctance Motor http://youtu.be/LXJUYumwh-k



Step Motor

Stepper motors have multiple "toothed" electromagnets arranged around a gear-shaped piece of iron .

To make the motor shaft turn, first one electromagnet is given power, which makes the gear's teeth magnetically attracted to the electromagnet's teeth. When the gear's teeth are aligned to the first electromagnet, they are slightly offset from the next electromagnet. When the next electromagnet is powered and the first is turned off, the gear rotates slightly to align with the next one, and from there the process is repeated.

Each of those small rotations is called a "step," with a specific number of steps making a full rotation. In this way, the motor can be turned by a precise angle.

http://keebraparkshs.eq.edu.au/EUREKA2009-tidalpower/BackgroundInformation.htm



t o

R o r

Commutation

No commutation

Stator coils driven by line voltage

Motor has a commutator to switch power to rotor coils

Electro-mechanical commutator

Drive

Switches power to stator coils, rotor position by sensing, either by discrete sensors, or feedback from coils, or open loop

Electronic switches

The rotor is ferromagnetic, not permanently magnetized; it has no winding

The rotor is a permanent magnet; it has no winding

The rotor includes a winding

Synchronous

Reluctance motor

BLAC motor

Induction motor

(Squirrel cage)

DC motor or PM motor

DC motor with wound stator http://en.wikipedia.org/wiki/Electric_motor

Switched Reluctance motor

BLDC motor

Induction motor

(controlled by inverter)



An inverter is an electrical device that converts direct current (DC) to alternating current

(AC); the converted AC can be at any required voltage and frequency with the use of appropriate transformers, switching, and control circuits.

http://en.wikipedia.org/wiki/Inverter_(electrical)

[10]



DC DC Converter [9]



DC DC Converter [9]



DC DC Converter [9]



A Battery Management System (BMS) is any electronic device that manages a rechargeable battery (cell or battery pack), such as by monitoring its state, calculating secondary data, reporting that data, protecting it, controlling its environment, and / or balancing it.

Monitor

A BMS may monitor the state of the battery as represented by various items, such as:

• Voltage: total voltage, voltage of periodic taps, or voltages of individual cells

• Temperature: average temperature, air intake temperature, air output temperature, or temperatures of individual cells

• State Of Charge (SOC) or Depth Of Discharge (DOD): to indicate the charge level of the battery

• State Of Health (SOH), a variously-defined measurement of the overall condition of the battery

• Air flow: for air cooled batteries

• Current: current in or out of the battery http://en.wikipedia.org/wiki/Battery_Management_System



Computation

Additionally, a BMS may calculate values based on the above items, such as:

• Maximum charge current as a Charge Current Limit (CCL)

• Maximum discharge current as a Discharge Current Limit (DCL)

• Total energy delivered since manufacture

• Total operating time since manufacture

Communication

A BMS may report all the above data to an external device, using communication links.

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



Protection

A BMS may protect its battery by preventing it from operating outside its safe operating area, such as:

• Over-current

• Over-voltage (during charging)

• Under-voltage (during discharging), especially important for Lead Acid and Li-Ion cells

• Over-temperature

• Under-temperature

• Over-pressure (NiMH batteries))

The BMS may prevent operation outside the battery's safe operating area by:

• Including an internal switch (such as a relay or solid state device) which is opened if the battery is operated outside its safe operating area[3]

• Requesting the devices to which the battery is connected to reduce or even terminate using the battery.

• Actively controlling the environment, such as through heaters, fans or even air conditioning http://en.wikipedia.org/wiki/Battery_Management_System



1.

한국자동차공학회 미래기획위원회

, 2030

2010

년

12

월

1

일

.

년 자동차 기술 전망

,

사단법인 한국자동차공학회

,

2.

유춘 , 임성일 , 김종율 , 김영일 ,

하이브리드 카

, 도서출판 골든벨 , 2010 년 4 월 15 일 .

3.

박한웅

,

전기자동차

,

도서출판 아진

, 2008

년

9

월

10

일

.

4.

GB 기획센터 , What’s

전기자동차 속이 보인다

, 도서출판 골든벨 , 2011 년 1 월 10 일 .

5.

C. C. Chan, “The State of the Art of Electric, Hybrid, and Fuel Cell Vehicles,” Proceedings of The

IEEE , Vol. 95, No. 4, April 2007, pp. 704-718.

6.

Karim Nice, Julia Layton, “How Hybrid Cars Work,” http://auto.howstuffworks.com/hybrid-car6.htm

7.

Mehrdad Ehsani, Yimin Gao, John M. Miller, “Hybrid Electric Vehicles: Architecture and Motor

Drives,” Proceedings of The IEEE , Vol. 95, No. 4, April 2007, pp. 719-728.

8.

Z. Q. Zhu, David Howe, “Electrical Machines and Drives for Electric, Hybrid, and Fuel Cell

Vehicles,” Proceedings of The IEEE , Vol. 95, No. 4, April 2007, pp. 746-765.

9. Jin-Sheng Lai, Douglas J. Nelson, “Energy Management Power Converters in Hybrid

Electric and Fuel Cell Vehicles,” Proceedings of The IEEE , Vol. 95, No. 4, April 2007, pp.

766-777.

10. Z. John Shen, Ichiro Omura, “Power Semiconductor Devices for Hybrid, Electric, and Fuel

Cell Vehicles,” Proceedings of The IEEE , Vol. 95, No. 4, April 2007, pp. 778-789.



환경 친화적 자동차: 신형 파워트레인

환경 친화적 자동차 : :

신형 파워트레인

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환경 친화적 자동차 : :

신형 파워트레인

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