Hybrid electric vehicle

Hybrid

Vehicles

Contents

Part I: what is a hybrid vehicle

Part II: Need for a hybrid

vehicle

Part III: Concept of

hybridization

Part IV: Architectures of

Hybrids

Part I :What is hybrid vehicle

Any vehicle which combines two or

more sources of power to operate is

called hybrid vehicle

Examples :

diesel – electric

gasoline - electric

HEV,EV?

A traditional vehicle has sole

propulsion by ICE or diesel engine

EV - Electric Vehicle, battery (or

ultra capacitor, fly wheels) operated

only. Sole propulsion by electric

motor

An HEV (Hybrid Electric Vehicle) is

a vehicle which involves multiple

sources of propulsions

Part II :Need for the hybrid

vehicle

Rising petrol/diesel prices

Pollution and the resultant global

warming

Noise

Part III: Concept of hybridization?

Multiple sources of power

Making ICE work in most efficient

range

Sizing of motor and ICE lower

compared

to conventional vehicles and EV

Modes of operation

Part IV: Architectures of

Hybrids

According to the method the energy sources are arranged

Parallel HEV: Multiple propulsion sources can be

combined, or drive the vehicle alone with one of the

energy sources

Series HEV: Sole propulsion by electric motor, but

the electric energy comes from another on board

energy source, such as ICE

Power split : it is a parallel and series hybrid

vehicle which additionally uses power spliter

Parallel hybrid

Fuel tank which supplies gasoline

to the engine

Set of batteries that supplies

power to electric motor

Both the engine and electric motor

can turn the transmission system

at the same time and the

transmission system then turns the

wheels

Parallel (cont.) When the Alternative power unit (APU) is

OFF the vehicle runs as an electric vehicle

When the APU is on the controller divides the

power between drive trains(propulsion) and

Batteries ( Energy storage)

Under acceleration more power is allocated to

drive train than batteries . During Idle or low

speed more power is allocated to batteries

The batteries provide Additional power to the

drive train and also to power auxiliary system

such as Air conditioner and heater

EXAMPLES Honda civic hybrid

Honda Insight 2nd generation

Mercedes Benz S400 Blue Hybrid

Advantages

ICE operation can be

optimized, with motor assist

or share the power from the

ICE

Flexible in configurations

and gives room for

optimization of fuel

economy and emissions

Reduced engine size

Possible plug-in hybrid for

further improved fuel

economy and emission

reduction

Disadvantag

e

Complicated control strategy

Complex transmission

SERIES HYBRID Similar to an parallel hybrid with an on board

generator

The vehicle runs in a Battery like a pure

electric vehicle until the battery reach the pre

determined discharge level

At that point the APU turns ON and Starts

Recharging the Battery

The APU is ON until the Battery recharged to

its predetermined level

The APU never directly powers the vehicle

The time duration of APU ON depends on the

size of the battery and APU itself

Since the APU is not directly connected to the

drive train it can run on its operating

condition. Hence fuel economy is more and

pollutant emission is low as compared to IC

EXAMPLES GM Motors – Chevy volt

Trinity – Saturn Vue SUV

Advantages

IC Engine mostly run at

optimal speed and

torque

IC Engine can be

turned OFF in zero

emission zone

Low floor possible

Low fuel consumption

High fuel efficiency

Disadvantag

es

Many energy

conversion so more

energy loss

Additional weight/cost

due to increased

components

POWER SPLIT HYBRID

It is also called as series-parallel hybrid

Here the power transmission some times is shared according to requirement

If the battery utilises complete power then it is called as series architecture

If the power shared among the engine and battery then it is called parallel architecture

Power is shared by a power splitter which is simply called as planetary gear set

EXAMPLES

Toyota – Prius

Ford Escape and Fusion

Advantages Disadvantages

IC Engine can

be turned OFF

IC Engine

speed can be

chosen by

adjusting

generator speed

Power vicious

may leading to

low efficiency

Relatively

complex

Expensive

Key advantages of HEVs Optimize the fuel economy

– Optimize the operating point of ICE

– Stop the ICE if not needed (ultra low speed and stops)

– Recover the kinetic energy at braking

– Reduce the size (hp and volume) of ICE

Reduce emissions

– Minimize the emissions when ICE is optimized in

operation

– Stop the ICE when it’s not needed

– Reduced size of ICE means less emissions

Quiet Operation

– Ultra low noise at low speed because ICE is stopped

– Quiet motor, motor is stopped when vehicle comes to

a stop, with engine already stopped

– Reduced maintenance because ICE operation is

optimized, less hazardous material, fewer tune ups,

longer life cycle of ICE

– Fewer spark-plug changes

– Fewer oil changes

– Fewer fuel filters, antifreeze, radiator flushes or

water

pumps

– Fewer exhaust repairs or muffler changes

Key Concerns of HEVs High initial cost

– Increased components such as battery, electric machines,

motor controller, etc.

Reliability concern

– Increased components, especially power system, electronics,

sensors

Warranty issues

– Issues on major electric components

– Dealership and repair shop not familiar with new components

Safety: high voltage system employed in HEV

Key concerns(cont.) Short Driving Range- Range anxiety

Recharging takes much longer time than refueling gasoline-lack of charging infrastructure

Battery pack takes space and weight of the vehicle which otherwise is available to the people

Grid load

ICE + Electric motor = Propulsion