of the page taken as our search engine crawled the Web.
The web site itself may have changed. You can check the current page or check for previous versions at the Internet Archive. Yahoo! is not affiliated with the authors of this page or responsible for its content.
42-V

T
HE
S
IMULATION OF

42-V
OLT
H
YBRID


E
LECTRIC
V
EHICLES


by
Andrew Campbell
Aishwarya Rengan
Jakob Steffey
with the assistance of:
Joshua Ormiston

Abstract: The objective of this project involves the selection and modification
of a hybrid electric vehicle (HEV) simulator in order to find the best possible
combination of engine and motor size in a sport utility vehicle. This combination will
increase fuel efficiency and lower harmful emissions. After investigating HEV
simulators, ADVISOR was chosen, the National Renewable Energy Laboratorys hybrid
electric vehicle simulator. This paper outlines the way ADVISOR models vehicles, what
changes are necessary in order to model a 42-volt battery system, and the simulations
done in order to maximize performance. The results show that in order to meet daily
driving demands, a 140 kW engine, coupled with a 15kW motor is the preferred
combination that will maximize fuel efficiency and reduce emissions.



Work done for McCleer Power Incorporated, under the direction of Dr. Pat McCleer, in partial fulfillment of
the requirements of Michigan State University MTH 844/890/490, advised by Professor Ronald Rosenberg

2
Table of Contents


Nomenclature ...................................................................................................................... 3
1. Introduction ................................................................................................................. 4
2. Hybrid Electric Vehicle Simulators ............................................................................ 5
3. A more detailed description of ADVISOR ................................................................. 6
4. Modifications of ADVISOR ....................................................................................... 9
5. Simulation
Procedure ................................................................................................ 11
6. Results and Discussion.............................................................................................. 12
7. Conclusions ............................................................................................................... 16
8. Limitations of this Study........................................................................................... 17
REFERENCES.................................................................................................................. 18
Appendix A. Sample MATLAB
®
Code (mc file)............................................................. 19
Appendix B. Important ADVISOR Modules.................................................................... 24
Appendix C. Forward and Backward-Facing Simulation Diagrams................................. 30
Appendix D. ADVISOR Output Incorrectly Modified Motor File................................ 32
Appendix E. Raw Data and Calculations .......................................................................... 34




























3

Nomenclature

Name

Definition
Ah


amp hour capacity
Ah
cap


maximum amp hour capacity
Ah
used

amp
hours
used
EC
watt-hour
energy
capacity
eff
motor
efficiency
I current
from
battery
P
bty



required battery power
P
bus_a


available power to the power bus
P
max


maximum energy storing system discharge
P
motor


power required from motor
P
total


total power used by motor
P
wire


power loss from wires
R
bty



internal resistance of single battery
R
intpack


resistance of battery
R
bty_new


new internal resistance of each battery
R
set



internal resistance of the set of batteries
R
tot



total internal resistance
Voc

open circuit battery voltage
Voc
batt


single battery open circuit current
V
bus_a


available voltage to the power bus



angular velocity of motor

torque required from motor c



torque required for charging battery int



torque needed to overcome motor inertia sum



total torque required from engine T

tractive
torque












4
1. Introduction
Electric vehicles have existed in one form or another since the late 19
th
century. In 1898
the German automaker Dr. Ferdinand Porsche built his first car. It ran on electric power.
These cars were always limited by the batterys available energy supply, but in the early
days of automobiles, their range per battery pack charge was competitive with the
distance a gasoline-powered car could travel on one tank of gas. As rapid improvements
in internal combustion engines were made, the electric car lost its market share to the
gasoline automobile. The electric car was never completely forgotten. Electric vehicles
made intermittent reappearances in America, especially as the result of the oil embargo in
the 1970s, and consumer demand for better fuel economy [1].
When emission regulations tightened in the last quarter of the 20
th
century and
engineers made breakthroughs in hybrid and electric vehicle technology, automobile
manufacturers began to look more seriously into vehicles with alternative power sources.
With current battery technology, electric vehicles are still severely limited by their range
per battery pack charge. Since electric motors yield quick acceleration and internal
combustion engines excel at steady speed operation, hybrid electric vehicle (HEV)
technology allows the car to draw upon the benefits from both devices.
HEVs meet both consumer needs as well as car manufacturer needs. They give
the consumer the ability to use the car for long periods of time without recharging. HEVs
also take a giant step forward in meeting low emission standards set by the Partnership
for a New Generation of Vehicles. HEVs also afford a much higher fuel economy than
that of a conventional vehicle.
The two configurations of hybrid electric vehicles are the series and the parallel
configurations. In a series configuration, there is no power transferred mechanically
between the gas engine and the wheels. In this type of configuration, power is converted
from chemical, to mechanical, to electrical, and back to mechanical energy. Essentially,
the gas engine powers the generator, which in turn can both charges the battery pack and
deliver power to the motor, and finally the electric motor powers the wheels. The
advantage of a series configuration is that since the engine never idles, there are fewer
emissions, so it is better for the environment. The disadvantage of this configuration
occurs on the highway since the power from engine is converted from mechanical to
electrical and then back to mechanical energy again. The series configuration is less
efficient than the parallel configuration because of the inefficiency in these energy
conversions.
In the parallel configuration, there is a direct mechanical connection from both the
electric power unit and the gas engine to the wheels. One possible parallel configuration,
the starter/alternator model, has a generator that doubles as an electric motor, coupled to a
gas engine. The batteries power the electric motor and the electric motor powers the
wheels. The gas engine also powers the wheels. In a parallel system, there is also a
possibility of a regenerative braking system every time the car brakes, the batteries are
charged. The advantage of a parallel configuration is that since both the electric motor
and the engine help in powering the wheels, the car generally has more power than a
series configuration. In addition, at highway speeds, this type of a configuration can
afford a higher fuel efficiency because there are fewer energy conversions than in a series
configuration. The disadvantage of a parallel configuration is that it usually releases
more emissions into the environment than a series vehicle [2].
5
The two HEVs currently on the market, the Toyota Prius and the Honda Insight,
operate with 274-volt and 144-volt energy storage systems, respectively. There is
increased speculation that the industry standard will change to 42-volt electrical systems.
The change to 42-volt systems will provide more protection against hazardous electric
shock. A 42-volt electrical system will maintain a level of safety that todays HEVs
cannot. Even conventional vehicles are moving in the direction of a 42-volt electrical
system in order to power the growing number of amenities in luxury vehicles and
possibly to introduce electrically actuated valves, electric water and oil pumps, and even
electrically heated exhaust catalyst systems. BMW now has prototypes of conventional
vehicles opera