1. Electric Motors as Automotive Prime Movers
P M V Subbarao
Professor
Mechanical Engineering Department
Eliminate Digestion System in an Artificial Horse to Mimic a Horse…

3. Anatomy of an Artificial Horse for Busy Roads ???

4. Vehicle speed and acceleration/deceleration in an FTP urban drive cycle

5. Energy Loss : Urban Driving : 3000 CC Engine Vehicle
Standby 8%
Aero 3%
Fuel Tank
100%
16%
13%
Engine
Driveline
Rolling 4%
Braking 6%
Driveline
Losses 3%
Engine Loss
76%
POWERTRAIN
VEHICLE-Related

6. Energy Loss : Highway Driving : 300 CC Engine Vehicle
Standby 0%
Aero
10%
Fuel Tank:
100%
23%
19%
Engine
Driveline
Rolling 7%
Braking 2%
Driveline
Losses 4%
Engine Loss
77%
POWERTRAIN
VEHICLE-Related

7. Low Irreversibility Prime Movers
Combustion Engines
Battery Electric
Fuel
Transmission
Engine
Battery
Transmission
Motor/ Generator

8. The Importance of Electric Vehicles:
Electricity can become is cheaper than fuel.
Electricity can come from renewable resources such as solar and wind power.
Electric cars pollute less than gas-powered cars.
Electric cars may require less maintenance than fuel-powered cars.
You don't even need to get your oil changed every 5,000 km!
By using domestically-generated electricity rather than relying on foreign oil, A country can become more independent.

9. Energy Loss : City Driving – Electric Vehicle
Aero
29%
Batteries
100%
90%
76%
Motor
Driveline
Rolling
35%
Braking
11%
Driveline
Losses
14%
Motor Loss
10%
POWERTRAIN
VEHICLE-Related

10. Mine to Wheel Efficiency
Mine-to-Tank
Tank-to-Wheels
31%
23%
Generation
33%
Transmission
94%
Plug-to-Wheels
76%
31%
76%
= 23%
Refining
82%
Transmission
98%
Pump-to-Wheels
16%
13%
80%
80%
16%
= 13%

11. Another Major Suitability Characteristic of Resource to Vehicle

12. Additional Inertial Losses in EVs
Gasoline :1 kg
Batteries
~ 5.4 MJ of Mechanical energy
~1 Li-ion battery (Car battery size)
17.9 kg
2.9 litre

13. Resistance & Power Requirement at Wheels : City Driving

14. Characteristics of A Typical variable-speed electric motor
The range of the constant power operation depends primarily on the particular motor type and its control strategy.

15. Speed Ratio of Typical variable-speed electric motor
At the low-speed region the motor has a constant torque.
The maximum speed at which a motor generates a constant (maximum) torque is known as base speed.
In the high-speed region the motor has a constant (maximum) power.
The highest speed at which the motor generates constant maximum power is known as maximum speed.
This characteristic is usually represented by a speed ratio x, defined as the ratio of its maximum
speed to its base speed.

16. Speed ratio & Speed–torque profile of a 60 kW electric motor

17. Tractive effort and power versus vehicle speed with different Motors

18. Mechanical Performance of A Traction Motor

19. Onroad Performance of A Vehicle
Basic onroad performance variables are:
Maximum Cruising Speed
Gradeability
Pick-up (Acceleration)
The maximum speed of a vehicle can be easily found by the intersection point of the tractive effort curve with the resistance curve (rolling resistance plus aerodynamic drag) in the tractive effort vs. vehicle speed diagram.

20. Tractive Effort Required Vs Vehicle Speed
Instantaneous Tractive Effort demanded by a vehicle:

21. Tractive Effort Available Vs Vehicle Speed
InstantaneousTractive Effort made available by Power unit:

22. Tractive effort vs. vehicle speed with a traction motor of x =2 and No Gear box.