HYBRID ELECTRIC VEHICLE

HYBRID ELECTRIC VEHICLE PRESENTED BY:ARJUN T RAM.EN.U4EEE13110S6 EEE BGUIDED BY: VIVEK A ASSISTANT PROFESSOR EEE

CONTENTSINTRODUCTIONARCHITECTURE OF HEV DRIVETRAINS 1)SERIES HYBRID DRIVETRAIN2)PARALLEL HYBRID DRIVETRAIN3)SERIES-PARALLEL HYBRID DRIVETRAINELECTRIC MOTOR DRIVES1)PERMANENT MAGNET(PM)MOTOR DRIVES2)INDUCTION MOTOR(IM) DRIVE3)SWITCHED RELUCTANCE MOTOR(SRM) DRIVE

ENERGY STORAGE1)CHEMICAL BATTERIES & ULTRACAPACITORS2)HYBRID ENERGY STORAGECONCLUSION

INTRODUCTIONA hybrid electric vehicle (HEV) uses two power sources to power the vehicle. At present, one power source is internal combustion (IC) engine (gasoline or diesel fueled) and the other is chemical batteries plus an electric motor drive.

ARCHITECTURE OF HEV DRIVETRAIN

CONCEPT OF HYBRID DRIVETRAIN9 Types available patterns of combining the power flows to meet load requirments.

Load power

Load power decomposed into Steady state(average)power & Dynamic power

Powertrain

Load Power Delivered

SERIES HYBRID DRIVETRAINBy adding a small IC engine/generator to the battery powered pure electric vehicle (EV) in order to make up the energy shortage of the batteries

AdvantagesMechanical decoupling between IC engine & driven wheels allows the IC engine operating at very narrow optimal regionSingle torque source(electric motor) to the driven wheels simplifies the speed control nearly ideal torque-speed characteristic of electric motor makes multigear transmission unnecessarysimple structure and drivetrain control and easy packaging

DisadvantagesTwice the energy form conversions cause more energy losses

Two electric machines are needed

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

Applications Heavy vehicles

Heavy commercial vehicles

Military vehicles

Buses

Locomotives

PARALLEL HYBRID DRIVETRAIN The engine and electric motor can directly supply their torque to the driven wheels through a mechanical couplingMechanical coupling may simply be a gearbox, pulley-belt unit or sprocket-chain unit, even a single axle

AdvantagesEnergy loss is less due to engine and electric motor directly supply torques to the driven wheels and no energy form conversion occurs

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

DisadvantagesMechanical coupling between the engine and the driven wheels, thus the engine operating points cannot be fixed in a narrow speed region

Complex structure and control

Applications Small vehicles

Eg:Honda Insight, Honda Civic,Ford Escape etc.

SERIES-PARALLEL HYBRID DRIVETRAINseriesparallel drivetrain by using a planetary gear unit to decouple the engine speed from the wheel speed

The engine power is split into 2 parts 1)Transferred to the Drivetrain 2)Generator

Series hybrid generator/motor speed is ve(opposite direction vs the torque)

Parallel hybrid Generator speed is +ve the generator/motor operates in motoring mode,adding power to driven wheels

Engine speed can be optimized by controlling the generator/motor speed

Planetary gear unit need for these functions

PLANETARY GEAR UNIT

AdvantagesCombines the advantages of series & parallel drivetrain

An additional electric machine and planetary unit makes the drivetrain more complicated

Instead of Planetary gear unit a floating-stator electric machine (Transmotor) Disadvantages

ApplicationUsed in Toyota Prius

ELECTRIC MOTOR DRIVES

Permanent Magnet(PM)Instand of rotor winding using Permanent Magnet

The overall weight and volume can be significantly reduced for given output torque, resulting in higher torque density

Due to the absence of rotor winding, rotor cu losses will not come in effect

Their efficiency is inherently higher than that of induction motors

The brushless dc motor and interior permanent magnet motor are two typical motor drives for HEV applications

In PM BLDC field weakened through production of a stator field component, which opposes the rotor magnetic fieldThe speed ratio x is usually lees than 2

Recently, the use of additional field windings to extend the speed range of PM brushless dc motors has been developed

PM hybrid motor = PMs + Field windings

This can achieve a speed ratio around 4

Major drawback of a relatively complex structure. The speed ratio is still not enough to meet the vehicle performance requirement, especially for off-road vehicles.

INDUCTION MOTORField orientation control (FOC) of an induction motor can decouple its torque control from field control

The motor to behave in the same manner as a separately excited dc motor

Extended speed range is accomplished by flux weakening

At the critical speed (Wmc) the breakdown torque is reached.The machine at the maximum current beyond this speed will stall the machine. A properly designed induction motor, e.g., spindle motor, with FOC can achieve a field weakened range of about three to five times its base speed.

SWITCHED RELUCTANCE MOTOR(SRM)Its simple and rugged construction

Simple control

Ability of extremely high speed operation

Hazard-free operation.

SRM can inherently operate with extremely long constant power range.Highly favorable for vehicle traction application. The major disadvantage of SRM drive is the high torque ripple and acoustic noiseExtended speed range by reducing the motor size and weight.High-speed operation is expected to reduce the torque rating and, thus, the current ratingDue to high speed there will be high mechanical loss(Aerodynamics drag & viscosity)Reduce these losses the shape of the rotor should be optimally designed for SRM drive

ENERGY STORAGE

Chemical Batteries & UltracapacitorsChemical Batteries

Almost all the vehicles use chemical batteries as their energy storage

Li-ion battery commonly used and its peak power upto 300 W/kg

Li-ion high power & high energy battery is having peak power upto 4000 and 600 respectively

Low cost batteries

Ultracapacitor

High specific powerHigh efficiencyExcellent temperature adaptabilityLong service lifeBut it has suffered from very limited specific energyUnit power cost is lower than that of batteriesDifficult to use Ultracapacitor alone as energy storage on HEV

Hybrid Energy StorageCombination of Ultracapacitor & Chemical BatteriesEnergy storage with high power and high energy can be obtained

Advantages

Battery current leveled by passively connected ultracapacitor

Small battery pack

High operating efficiency

Easy thermal management

Longer battery life

CONCLUSIONUsing the concept of Hybridization of cars results in better efficiency and also saves a lot of fuel in todays fuel deficit world.

A hybrid gives a solution to all the problems to some extent(Air pollution).

In the short run HEVs seem to be a viable alternative

REFERENCES[1]Mehrdad Ehsani, Fellow IEEE, Yimin Gao, and John M. Miller, Fellow IEEE, Hybrid Electric Vehicles: Architecture and Motor Drives,page 719-728, Vol. 95, No. 4, April 2007 ,proceedings of ieee

[2]Wikipedia