Designing and Optimizing a Plug-In Hybrid Electric Vehicle

HYBRID ELECTRIC TRANSPORT
SATYAJEET UDAVANT PAGE NO 1
PROJECT REPORT
HYBRID ELECTRIC TRANSPORTATION
ME 50105
DESIGN AND EVALUATION OF PLUG-IN HYBRID
ELECTRIC VEHICLE (PHEV) POWERTRAIN
SATYAJEET UDAVANT
IUPUI, INDIANAPOLIS
SUBMISSION: MAY 1, 2016

Abstract:
Hybrid technology is an emerging and promising field of sustainable future in
especially automobile industry. There are various types of powertrain configuration
possible. These different possibilities give opportunity to work on various aspects of
automobile as per ones need. In recent years hybrid technology has taken a good grip and
many companies are embracing this technology as its supportive to environment with zero
emissions. In the following project I am using a Parallel Pretrans PHEV 2 wheel drive
midsize car. For simulation purposes, a software named Autonomie, is used. The focus of
this project is in two main areas.
1. Increase in efficiency, better performance fuel economy, and battery aspects among
the least. Varying a sect of parameters this can be achieved.
2. To give a comparative study of the various powertrain configuration.
After completing more than 70 simulations, I came to a conclusion and the report explores
the same. Most of the simulations were invalid as the configurations at times were absurd
or the specifications were not within the permissible limits. For most of the valid
simulations a base model was set and then changing a few parameters above mentioned
goals were achieved. A final model was set to compare the achieved results with that of
the base model. In between the other simulations were used to give a comparative study.
Analysis was made using the various plots of State of charge, Fuel consumption, fuel rate,
driver demand of acceleration, power out, power in, energy out, energy in, both for engine
and motor, and other battery performance. Simulations for Urban Dynamometer Driving
Schedule (UDDS) and HWFET rating for highway driving cycle were made.

Objective:
The primary objective of this report is to set a vehicle model/configuration and while
changing the various parameters obtain better fuel economy, better performance. Design
and optimization of component sizes. Design of energy management algorithm for the
powertrain. Use of Autonomie simulation software to build the model. Analyze the
performances of energy management algorithm. Result discussion is performed at the end
of the report. With these objectives in mind, I hope this report will serve as an example for
research and analysis in above mentioned aspect of Hybrid technology. Two different
approaches are made to achieve the desired goal. Varying the parameters simulations are
performed and a comparison is made between the Urban Driving Dynamometer Schedule
(UDDS) and Highway fuel Efficiency Test (HWFET) rating of the hybrid car. Acceleration
performance and gradeability is also considered while performing the simulation.
Literature review:
Hybrid Philosophy:
1. Operate electric motor first (less emissions/less fuel consumed).
2. Add gasoline engine only when needed.
3. Operate gas engine at the best rpm and throttle setting, that is, operate on minimum
fuel consumption line in engine map.[1]
Hybrid cars have many modes of operations and so there are many powertrain
configurations possible. Based on Drivetrain, they can be classified as:
Series- Hybrid electric drivetrain.
Parallel- Hybrid electric drivetrain.
Series-Parallel electric drivetrain.
There are different types of Hybrid cars:
Plug-in hybrid car.
Electric cars
Fuel-cell hybrid cars
Solar powered cars etc

For the purpose of this project Parallel Pretrans PHEV Autotrans 2-wheeldrive midsize
car is considered.
Fig [1] - Parallel Pretrans PHEV
Here, as shown in the figure both the engine and the torque are modified in the
transmission. However the engine and motor are to have the same speed range. A PHEV
is a drivetrain in which engine supplies its mechanical power directly to driven wheels.
Here IC Engine is supported by the Electric motor which is mechanically coupled to the
driveline.[2]
Advantages of Parallel driveline over Series driveline are:
Both engine and motor directly supply torques. Its compact. Traction motor is smaller than
in series.

Batteries:
The lithium batteries are of following types:
• Lithium polymer batteries • Lithium ion batteries
Battery is defined with its specifications and properties:
• specific energy • energy density • specific power • typical voltages
• amp hour efficiency • energy efficiency • commercial availability
• cost, operating temperatures • self-discharge rates • number of life cycles
Autonomie has been designed to be useful as a single tool in all of the different phases of
Model Based Design of the Vehicle Development Process (VDP). Model Based Design is
a math-based visual method for designing complex control systems. It is being used
successfully in many motion control, industrial, robotics, aerospace, and automotive
applications. It provides an efficient methodology that includes four key elements in the
development process which are as follows: modeling a plant (from first principles or
system identification), synthesizing and analyzing a controller for the plant, simulating the
plant and controller together, and programming/deploying the controller. Model Based
Design integrates all these multiple phases. It provides a common framework for
communication throughout the entire design process.[3]
Fig[2]- Sample of user
interface of Autoonmie
Simulation Software.

Simulation:
A total of around 70 simulations were made to learn and understand the various
aspects of the software autonomie. Most of the time with absurd results and the invalid
configurations the simulation was a disaster but failures taught the right way to use the
system. With the following parameter as base model, model was simulated for UDDS cycle
and HWFET cycle.
Parameters:
Vehicle model- Autotrans PHEV Pretrans 2-WheelDrive midsize vehicle.
Honda Accord (chassis and final drive)
Fig[3] model setup –base model
Base model includes: Motor of size, 34 kw. Engine size considered is 76 kw. Wheel used is R17
with aspect ratio 235/35. Drag Coefficient is 0.3 and frontal area is 2.275m2
.

Simulation result:
Simulation results describe the results in four columns UDDS, HWFET, acceleration and
gradeability. Important figures marked are described here.
Fuel Economy: 106 UDDS- 107 HWFET
Final SOC: 80.81 UDDS – 75.89 HWFET
Here you can see that the Final SOC of UDDS is more than HWEFT. A logical explanation
to this is regenerative braking. Because in urban driving a car has to stop and start
frequently. Due to this frequent brakes need to apply which generates energy and is stored
in battery. UDDS cycle is different than HWFET because of urban traffic and signal stops.

Following three graphs describes the following in respective manner:
1. Engine plant fuel consumption. Green line steeps early than blue as it represents the
HWFET cycle were engine is more utilized highway. As motors are more used in
urban cycle the blue line in graph raises gradually.
2. This describes the fuel rate. With the same explanation as above.
3. Torque output is described in graph 3.

Following graph describes power output of the motor. Blue line describes the urban cycle
as the alternative high peaks in blue line represents the frequent use of motor.
State of charge of the battery pack is depicted in the following graph.

The energy balance and the energy losses for the fuel efficient engine are as shown below:
Energy flow of the car is represented by the red and blue arrows , size of the arrow is with
respect to the amount of energy transferred. Energy generated from regenerative is storedin
battery.

Final model simulation details;
Changes in first model:
Final model includes:
 Motor of size, 40 kw.
 Engine size considered is 82 kw.
 Wheel used is R18 with aspect ratio 235/35.
 Drag Coefficient is 0.27 and frontal area is 2.0 m2
.

Simulation results:
1. Engine power output
2. Engine torque output
3. Fuel Consumption

1. Battery Energy output
2. Battery power out
3. Battery State of Charge
Green line steeps early than blue as it represents the HWFET cycle were engine is more
utilized highway. As motors are more used in urban cycle the blue line in graph raises
gradually

For simulation 2:
UDDS cycle The energy balance and the energy losses for the fuel efficient engine are as
shown below:
Energy flow of the car is represented by the red and blue arrows , size of the arrow is with
respect to the amount of energy transferred. Energy generated from regenerative is stored
in battery

Comparing the two models:
Fig[4] comparative table for the model parameter

BASE MODEL: Vehicle Propulsion Architecture.

This figure gives the comparison between the Acceleration and Gradebility between the
two models under consideration.
Acceleration performance is improved from 10.4 to 11.7
Fuel Economy of the first model is 10.23 and that of the final model is 13.39

MODEL #1
MODEL #2

Following is the comparison between the UDDS and HWFET cycle of Initial and Final
model.

Conclusion:
Hence we can conclude that using certain performance parameters in and applying
the necessary changes, we can simulate a car with better performance. These performances
are then analyzed in various different parameters like state of charge of battery,
acceleration, fuel economy etc.
We can also analyze the basic functions of UDDS and HWFET cycles and their role in
vehicle performance. More technological advances and our ability to read into the
performance data insures better cars in future.
Design and simulation of the vehicle is performed successfully.
Energy flow of the car is studied and analyzed.
Energy optimization is achieved in second model.

References:
[1] http://nptel.ac.in/courses/108103009/28 -web content for HEVs and EVs
[2] M. Ehsani, Modern Electric, Hybrid Electric and Fuel Cell Vehicles:
Fundamentals, Theory and Design , CRC Press, 2005
[3] http://en.openei.org/wiki/Autonomie_Automotive_Simulation_Tool
Figures:
[1] pretransmission parallel hybrid power train
[2] Sample of user interface of Autonomie http://energy.gov/eere/articles/models-
move-vehicle-design-forward
[3] model setup of the base model in Autonomie software.
[4] comparative table for the changes that were made in the base parameter.
THE END

Designing and Optimizing a Plug-In Hybrid Electric Vehicle

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