01_electric powertrain structures base

8/12/2019 01_Electric Powertrain Structures Base

1/4

Electric Powertrains

MIT Electric Vehicle Team, April 2008

An electric vehicle (EV) is a vehicle that is powered, at least in part, by electricity EV

con!i"#rations incl#de battery electric vehicles ($EVs) which are powered by %00& electricener"y, vario#s hybrid'electric vehicles (EVs), and pl#"'in hybrid electric vehicles (EVs)This s#mmary presents the di!!erences between these basic EV con!i"#rations

Battery Electric Vehicles

A battery electric vehicle ($EV) is a vehicle that is powered entirely on electric ener"y, typicallya lar"e electric motor and a lar"e battery pac* $ased on the type o! transmission+ the #se o! a

cl#tch, "earbo, di!!erential, and !ied "earin"+ and the n#mber o! battery pac*s and motors there

are many variations on the $EV desi"n owever, a basic $EV system is shown in -i"#re %

Battery Motor/

Generator

Transmission

Battery Motor/

Generator

Transmission

Figure 1:.chematic o! a battery electric vehicle ($EV) powertrain

Mild Hybrid Electric Vehicles

/nli*e a $EV, a hybrid electric vehicle (EV) relies on two ener"y so#rces, #s#ally an internal

comb#stion en"ine and an electric battery and motor"enerator A Mild ybrid is the least

electri!ied type o! EV A Mild ybrid is a conventional internal comb#stion en"ine (I1E)vehicle with an oversied starter motor that can also be #sed as a "enerator, #s#ally called an

inte"rated starter'"enerator (I.3) or a belted alternator starter ($A.), and an oversied battery

that powers and is rechar"ed by the motor A simple Mild ybrid system is shown in -i"#re 2 Ina Mild ybrid, the en"ine m#st always be on while the vehicle is movin" owever, the

motor"enerator can be #sed to enable idle stop in which the en"ine is t#rned o!! while the

vehicle is at idle The motor"enerator can be #sed at hi"h loads to assist the en"ine and increasevehicle per!ormance At low loads, it increases load on the en"ine and rechar"es the electric

battery


2/4

Battery Motor/

Generator Transm

issionEngine

Liquid

Fuel

Figure 2:.chematic o! a Mild ybrid powertrain

Series Hybrid Electric Vehicles

In a .eries ybrid there is a sin"le path to power the wheels o! the vehicle, b#t two ener"y

so#rces As shown in !i"#re 4, the !#el tan* !eeds an en"ine which is co#pled to a "enerator to

char"e the battery which provides electrical ener"y to a motor"enerator to power the wheelsthro#"h a transmission altho#"h a direct co#plin" can also be #sed The motor"enerator is also

#sed to rechar"e the battery d#rin" deceleration and bra*in"

Battery

Motor/

Generator

Transmiss

ion

Generator

Engine

Liquid Fuel

Figure 3:.chematic o! a .eries ybrid powertrain

The .eries ybrid can operate in the !ollowin" seven modes5

En"ine only traction

Electric only traction

ybrid traction

En"ine Traction and $attery 1har"in"

$attery 1har"in" and 6o Traction

7e"enerative $ra*in"

ybrid $attery 1han"in"


3/4

Altho#"h most .eries ybrids #se an I1E, it is also possible to desi"n a .eries ybrid #sin" a

-#el 1ell powered by hydro"en, creatin" a -#el 1ell Electric Vehicle (-1EV)

Parallel Hybrid Electric Vehicles

In a arallel ybrid, there are two parallel paths to power the wheels o! the vehicle5 an en"ine

path and an electrical path, as shown in !i"#re The transmission co#ples the motor"enerator

and the en"ine, allowin" either, or both, to power the wheels 1ontrol o! a arallel ybrid is

m#ch more comple that !or a .eries ybrid beca#se o! the need to e!!iciently co#ple themotor"enerator and en"ine in a way that maintains driveability and per!ormance

Battery Motor/

Generator TransmissionEngine

Liquid

Fuel

Figure 4:.chematic o! a parallel hybrid powertrain

The arallel ybrid can operate in the !ollowin" !ive modes5

En"ine only traction

Electric only tractionybrid traction

7e"enerative $ra*in"

$attery char"in" !rom the en"ine

Series-Parallel Hybrid Electric Vehicles

A .eries'arallel EV has both .eries and arallel ener"y paths As shown in !i"#re 9, a system

o! motors andor "enerators that sometimes incl#des a "earin" or power split device co#plesallows the en"ine to rechar"e the battery Variations on this con!i"#ration can be very comple

or simple, dependin" on the n#mber o! motors"enerators and how they are #sed These

con!i"#rations can be classi!ied as 1omple hybrids (s#ch as the Toyota ri#s and -ord Escapeybrids), .plit'arallel hybrids, or ower'.plit hybrids


4/4

Battery Motors/

Generators Transm

issionEngine

Liquid

Fuel

Figure 5:.chematic o! a series'parallel hybrid powertrain

Plug-in Hybrid Electric Vehicles

A pl#"'in hybrid electric vehicle (EV) is an EV that can be pl#""ed'in or rechar"ed !rom

wall electricity EVs are distin"#ished by m#ch lar"er battery pac*s when compared to other

EVs The sie o! the battery de!ines the vehicle:s All Electric 7an"e (AE7), which is "enerallyin the ran"e o! 40 to 90 miles EVs can be o! any hybrid con!i"#ration Altho#"h no EVs

are available on the mar*et today, a n#mber o! companies have be"#n to sell conversion *its and

services to convert a standard EV into a EV by addin" additional battery capacity andmodi!yin" the vehicle controller and ener"y mana"ement system

01_electric powertrain structures base

Documents