Transcript Electric Snowmobile Utah State University

Presented by:
Ashley Kelly
Nathan Hansen
Utah State University
Electric Snowmobile Team
http://www.engineering.usu.edu/mae/projects/es
Overview
•Team Structure and Organization
•Objectives
•Comparison to Stock
•Testing and Energy Models
•Modifications
•Results
•Features of Final Product
•Future Work and Conclusion
Our Team
Top row, left to right: Nathan Hansen (team leader), Denton Johnson, Byard Wood (faculty advisor),
Scott Duhadway, Rob Silver, Paul Carpenter
Front row, left to right: Nathaniel Hollingsworth, Ashley Kelly, Jed Jenkins, Merin Swasey,
Steven Hanson, Ira Tibbits (Not pictured: Justin Maughan)
USU Electric Snowmobile Team Organization
Specifications
Chassis
97 Polaris Indy Trail 500
Motor
8” Advanced DC 203-06-4001
Batteries
10x Universal Power UB12550 AGM
1x auxiliary control 12V lead acid
Stock
Range
10 miles at 20 mph
Top Speed
35 mph
Acceleration
500 ft in 11 sec.
Weight
850 lb
Modified Electric
Video Comparison of
Stock vs. Electric Conversion
(1997 Polaris Indy Trail 500)
Dyno Testing the Motor
Field Testing to Find
Energy Requirements
It was desired to know the energy
requirement of the snowmobile
at various velocities. This was
accomplished by “drag testing” and
gathering force vs. velocity data.
Modeling and Testing
Energy models were built based on testing results and theoretical analysis.
These were built using Mathsoft Mathcad, Microsoft Excel, and Intel
FORTRAN 90/95 software. The use of this software made perturbation of
possible solutions simple, and helped uncover the full scale effect of
changing variables.
Acceleration Test
Overall Drive Time (s) to
Time (s) to
Vmax
Ratio (x:1) 30.48m (100ft) 152.4m (500ft) (kph)
4
2.89
10.21
65.0
4.25
2.91
10.44
62.8
4.5
2.93
10.66
60.7
4.75
2.96
10.9
58.9
5
2.98
11.13
57.2
5.25
3.01
11.35
55.6
5.5
3.05
11.58
54.2
5.75
3.08
11.81
52.8
6
3.12
12.03
51.5
Constant Velocity 32 kph (20mph)
Motor
Theoretical
Speed Current Battery Life Theoretical
(Rpm) (Amps)
(min)
Range (km)
3842
117.4
12.5
6.7
4083
114.2
13.0
6.9
4323
111.3
13.4
7.2
4563
108.8
13.8
7.4
4803
106.5
14.2
7.6
5043
104.4
14.6
7.8
5283
102.5
14.9
8.0
5523
100.7
15.3
8.2
5764
99.1
15.6
8.4
Example of how energy models were used: Selection of drive train gear ratio, based
on energy requirements of the snowmobile, discharge characteristics of the battery, and
motor performance. Decisions were made towards meeting competition requirements.
Motor Testing: Series vs. Parallel
The electric motor was rewired so that half of the four field coils could be
run in parallel. This was done to reduce the amount of current that would
be required at cruising speeds. The discharge rate of the batteries is the
largest factor in electric snowmobile range, and any decrease in discharge
rate leads to a logarithmic increase in range.
Current (Amps)
RPM vs Current, avg 24 kph (15 mph), CVT
30 Jan 2006, USU Electric Snowmobile Team
~9-16% difference in current at equivalent rpm
120
100
80
60
40
20
0
0
1000
3000
2000
Motor RPM
Series Current
4000
Parallel Current
5000
Parallel
Series
Testing Progression
Major Milestones in Testing
Date
Purpose of Test
Changes Since Last Test
Range (miles)
11/28/2005
range
first test of the year
2.9
12/17/2005
range
track tension optimized
6.5
1/21/2006
series/parallel testing
motor rebuilt, DAQ system
-
1/25/2006
range
direct drive transmission
9.5
1/26/2006
range
CVT transmission
8.5
3/7/2006
abuse and handling
suspension rebuilt
-
3/10/2006
final pre-competition test
(total miles in testing this school year: 67.4 miles)
-
Modifications
Many of the stock components in the snowmobile had to be
redesigned to accommodate the requirements of electric vehicle
parts. Possible designs were analyzed for performance and integrity.
For example, the electric motor mount was rebuilt:
Original electric motor mount:
Yielded excessively under motor load
Current electric motor mount:
More appropriate to performance of motor
Suspension
Modification was required in the rear suspension to handle additional
loading from the batteries, and also to improve performance. The new
suspension gives twice as much rear travel as the stock design did
when loaded with batteries. Rider Comfort also increased.
User Friendly
•Batteries charge off of 120 V AC household current
•Charge time approximately 3.5 hours
•Easy quick disconnect to isolate high voltage system
•Drive and control just like a normal snowmobile
•Reverse
•Towing hitch
•Comfortable seat
•Stow compartments in seat
•Simple dash gauges to indicate speed, distance, current,
voltage, and motor speed
Towing Capability and Utility
SnoWatt towing a 1995 Jeep Grand Cherokee (4345 lbs)
Replaceable, Durable, and Low Cost
•Aftermarket parts are COTS (Commercial Off The Shelf) technology
•Motor: Advanced DC 203-06-4001
•Controller: Curtis 1221-C
•Throttle: Curtis PB-6 Potbox
•Contactor: Kilovac Czonka
•Batteries: Universal Power UB12550 VRLA AGM
•Drive Train: Gates Polychain GT HTD
•All major parts engineered to provide an additional safety
factor in endurance and performance
•Parts are readily available from a variety of suppliers
•Charging system is “plug and play,” using a standard power outlet
•All other components remain stock
Cost
•TICA Cost of $2208.25 for fully electric conversion
Safety
Anderson style disconnect
for high voltage
Additional guards for mechanical
components
High voltage
contactor
Warning lights to
indicate connected
high voltage
Not Pictured:
•Sealed, vented, and secured battery
box
•In-line fuses in all electrical systems
•All major components are hermetically
sealed
•Handle bar and tether kill switch
•Inertial kill switch (removed
for performance handling)
Performance
•Improvements:
•Zero on-site Emissions
•Substantial Reduction in Noise (no motor or clutch noise)
•Good Acceleration (0-500 feet in 10.9 seconds)
•Excellent Utility Performance
• Compromises:
•Range (9-12 miles)
•Weight (nearly 300 pounds heavier)
•Top Speed (reduced to 35 mph in direct drive system)
Range and weight could be massively improved just by
dropping in a different battery technology.
Future Work
Much of efforts this year have been to establish a foundation that future
teams may build on. Plans for next year’s CSC snowmobile include:
•Weight Reduction!
•Reduction in energy requirements
•Friction in track
•Drive Train losses
•Noise reduction in mechanical components (track, chain)
•Improvements in battery technology
•Improvements in suspension and handling
Conclusion
•Our strength is in simple design and solid engineering choices
•Unique electric approach is a quiet, clean, and practical solution
•Possible Markets:
•Scientists
•National Parks and Recreation Areas
•Utility Users (snowmobile equivalent of heavy duty truck)
•Environmentally conscientious snowmobilers
•Short range commuting
•The involvement of the National Science Foundation (summer 2006)
and Yellowstone National Park lend great credibility and further
the possibility of long term research into this exciting new
technology.