ELECTRIC AND HYBRID ELECTRIC VEHICLE

BRANCH-MECHANICAL ENGG.

SEMESTER-6^TH SEM

NAME-Er.MANAS RANJAN MOHANTA

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OUTLINE

• Electric Car History
• Concept of Electric and Hybrid Electric Vehicles
• Type of Electric Vehicles
• Electric Motor Drives for BEV and HEV
• Sensorless PM Brushless Motor Drive for EV Traction

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Phase I

Whether by changing stations or exchangeable batteries, the first phase of the electric car started from late 1890’s.

The first commercial application was in 1897.

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Lohner-Porsche Car (1900-1901) with electric hub wheel motor

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Electric Car History

Phase II

The second significant phase of electric cars was the result of the energy crisis of the 1970s and 1980s.

In the early 1990s, USA government organizations began to push for more fuel efficient, lower emission vehicles with the ultimate goal of moving to zero emission vehicles, such as electric vehicles.

However, during this phase, very few units were produced.

Phase III

The Future.

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Electric Car History

• Single or multiple energy source: Fossil fuel, Battery, Fuel cell…
• Single or multiple energy converter: Chemical/Mechanical/Electrical;
• Mechanical coupling and transmission.

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Concept of Electric and Hybrid Electric Vehicles

Traction systems of EV / HEV

Battery Powered Electric Vehicle : BEV

Series Hybrid Electric Vehicle : Series HEV

Parallel Hybrid Electric Vehicle : Parallel HEV

Series-Parallel Hybrid Electric Vehicle : Series-Parallel HEV

Plug in Hybrid Electric Vehicle : PHEV

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Type of Electric Vehicles

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The BEV is propelled by an electric motor only ;

One energy source only is taken on-boards i.e. battery.

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Advantage

1. Zero Emission Vehicle ZEV.
2. Single torque source (electric motor) to the driven wheels → simple speed control.
3. Nearly ideal torque-speed characteristic → multigear transmission unnecessary.
4. Simple structure and control of the traction system.
5. Can use renewable sources for charging.

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Disadvantage

Limitation of driving range and speed.

It is mainly a city car.

Battery Powered Electric Vehicle

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Battery Powered Electric Vehicle

Components and Energy Flow of BEV Traction System

1. The electric machine (Motor) delivers mechanical power to load;
2. The electric machine (Generator) obtains mechanical power from load

and charge batteries (Regenerative braking).

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Battery Powered Electric Vehicle

Example of Compact Design

Ford Focus Electric Vehicle

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Series Hybrid Electric Vehicle

Developed by adding a small IC engine/generator to the BEV.

Usually used in heavy vehicles: heavy commercial vehicles, buses and even locomotives.

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Advantage

1. Single torque source (electric motor) to the driven wheels → simple speed control.
2. Nearly ideal torque-speed characteristic → multigear transmission unnecessary.
3. Simple structure and control of the traction system.
4. Mechanical decoupling between the IC engine and the driven wheels  

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Disadvantage

1. Twice the energy form conversions (mechanical/electrical/mechanical).
2. Two electric machines are needed (electric generator and traction motor).
3. Big traction motor since it is the only torque source of the driven wheels.

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Series Hybrid Electric Vehicle

Components of Series HEV Traction System

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Series Hybrid Electric Vehicle

Energy Flow of Series HEV Traction System

1) IC Engine alone delivers power to load;

2) Battery alone delivers power to the load;

3) Both IC Engine and Battery deliver power to load at the same time;

4) Battery obtains power from load (regenerative braking);

5) Battery obtains power from IC Engine ;

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6) Battery obtains power from IC Engine and load at the same time;

7) IC Engine delivers power to battery, and battery delivers power to load;

8) IC Engine delivers power to load and to battery at the same time;

9) IC Engine delivers power to load, and load delivers power to battery.

!!! Necessity of Energy Management System

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Series Hybrid Electric Vehicle

Example of Compact Design

Lotus PROTON Series HEV

Torque density

The torque density is an important criterion of the electric motors.

It reflects the volume and weight of machines at given torque demand.

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Electric Motor Drives for BEV and HEV

Required Features of Electric Motor Drives

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• High Efficiency
• Good Dynamic Performance
• High Power Density
• Low cost

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• Reliability
• Overload currents capability
• Maintenance Free
• Temperature resistance
• Fault-tolerance

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Electric Motor Drives for BEV and HEV

a matter of safety and life it self

a matter of energy and environment conservation

and quality of life

How to develop a reliable and high efficiency torque-speed profile for the traction system ?

• The ideal torque-speed profile is the constant power in all the speed ranges.
• EVs require a constant-torque region at low speed and a constant-power region at high speed.
• Well-controlled electric drives provides easily such profile.

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Ideal Torque-Speed Profile for reliable and efficient traction system

P = T x W

P: Power;

T: Torque;

W: Speed.

With IC Engine powered vehicle, a multigear transmission is necessary to impose

a torque-speed profile which is close to the ideal profile.

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Ideal Torque-Speed Profile for reliable and efficient traction system

PM Motors are the best for traction systems

The magnetic field is excited by high-energy PMs, resulting in higher torque density.

The absence of rotor winding and rotor copper losses yields to a very high efficiency.

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Other advantages

• High Reliability
• Excellent Dynamic Performance
• Overload currents capability (2-4 times the rating)
• Maintenance Free (Brushless)
• Relatively Expensive

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Permanent-Magnet Synchronous Motor Drives

Adopted motors

Surface-Mounted PM (SPM) Interior PM (IPM) motors

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Permanent-Magnet Synchronous Motor Drives

Toyota IPM Motor

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Remy SPM Motor

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Limitations

• PM motor has short constant power range due to its limited field weakening capability.
• The rare-earth magnet price instability is seriously questioning the adoption of PM motors.

Solutions

• Synchronous PM drives require dedicated control algorithm for flux-weakening operation

over a wide speed range for traction application.

• Multilayer IPM motors are more suitable for replacing the rare-earth magnets with cheaper

ferrite magnets.

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Permanent-Magnet Synchronous Motor Drives

Flux-weakening control IPM multilayer motor

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Permanent-Magnet Synchronous Motor Drives

Field orientation control (FOC) of an induction motor can decouple its torque control

from field control.

Extended speed range operation with constant power beyond base speed is

accomplished by flux weakening.

The long field weakened range, makes the induction motor very suitable for vehicle application.

Other advantages

• High Reliability
• Excellent Dynamic Performance
• Maintenance Free (Brushless)
• Low price

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Induction Motor Drives

Limitation

The presence of breakdown torque limits its extended constant power operation.

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Induction Motor Drives

Switched reluctance motor (SRM) is a good candidate of future electric propulsion system:

• Simple and rugged construction,
• Simple control and ability of extremely high speed operation.
• SRM can inherently operate with extremely long constant power range.
• Hazard-free operation.

The major disadvantage of SRM drive is the high torque ripple and acoustic noise.

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Switched Reluctance Motor (SRM) Drives

Classical configuration

The PM Electric Motor is inserted inside the wheel.

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Fundamental advantages

• Gearboxes, driveshafts and differentials are no longer necessary.
• Elimination of weight while improving efficiency of power transfer.   
• Reduce packaging space on the vehicle platform.
• Each hub motor can be controlled independently, providing greater performance of

control and vehicle dynamics.�

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Special Motor Design: in-Wheel Hub Motor Technology

Recent design

The Motor Drive is inserted inside the wheel .

More advantages

• Reduce fuel consumption by 30 % vs ICE vehicle.
• Packaging space on the vehicle platform is extremely reduced.

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Protean Hub Motor 2014: 75Kw, 85% regenerative braking

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Special Motor Design: in-Wheel Hub Motor Concept

Role of power electronics for EV and HEV

• Battery Charger.
• Battery cell voltage equalizer.
• Electric Drives.

Commercial power converters are high efficiency converters (95%).

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Power Electronics Converters

Electric Drives Battery Charger

The considered motor

PM Brushless in-wheel Motor.

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Objectives

Design an appropriate control scheme in order that:

1. The motor drive can develop the required high starting torque.
2. The efficiency of the drive is improved.

Proposed Technique

1. Starting up as Brushless DC Motor using Hall-effect sensors.
2. Driving the motor as Brushless AC Motor using Sensorless Field Oriented Control.

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Sensorless PM Brushless Motor Drive for EV Traction

Brushless DC Motor

• Brushless DC Motor is characterized by Trapezoidal EMF.
• The motor phases should be supplied with currents in

the form of rectangular pulses.

• Hall-effect sensors are used with BLDCM in order to

manage the phases commutation sequence.

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PM Brushless Motor Types efficiency issue

Brushless AC Motor

• Brushless AC Motor ideally has sinusoidal EMF.
• The motor should be supplied with sinusoidal currents.
• High resolution encoder is necessary to generate

sinusoidal currents.

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PM Brushless Motor Types and efficiency issue

Brushless DC Motor driven with rectangular current

• More frequency harmonics are present in the current waveform
• Torque ripples are relatively intense

(weighing 13% of the rated torque).

• Additional noise, vibration and power losses.

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Current waveform and efficiency

Brushless AC Motor driven with sinusoidal current

• Quite larger torque is produced for the same RMS current.
• Reduction in power losses occurs.
• Gain of 7.5% in energy consumption.

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Unfortunately, Brushless AC control mode requires

an encoder providing precise angle measurements.

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Current waveform and efficiency

Sensorless

Position and speed estimator instead of an encoder.

Field Oriented Control

Torque and speed control.

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Sensorless Field Oriented Control

Thank You

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