http://www.engineering.usu.edu/mae/projects/es

Presented by:Presented by:

Ashley KellyAshley Kelly Nathan HansenNathan Hansen

Utah State University Utah State University Electric Snowmobile TeamElectric Snowmobile Team

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

Stock Modified Electric

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

Range 10 miles at 20 mph

Top Speed 35 mph

Acceleration 500 ft in 11 sec.

Weight 850 lb

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 TestingEnergy 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.

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, andmotor performance. Decisions were made towards meeting competition requirements.

Overall Drive Ratio (x:1)

Time (s) to 30.48m (100ft)

Time (s) to 152.4m (500ft)

Vmax (kph)

Motor Speed (Rpm)

Current (Amps)

Theoretical Battery Life

(min)Theoretical Range (km)

4 2.89 10.21 65.0 3842 117.4 12.5 6.74.25 2.91 10.44 62.8 4083 114.2 13.0 6.9

4.5 2.93 10.66 60.7 4323 111.3 13.4 7.24.75 2.96 10.9 58.9 4563 108.8 13.8 7.4

5 2.98 11.13 57.2 4803 106.5 14.2 7.65.25 3.01 11.35 55.6 5043 104.4 14.6 7.8

5.5 3.05 11.58 54.2 5283 102.5 14.9 8.05.75 3.08 11.81 52.8 5523 100.7 15.3 8.2

6 3.12 12.03 51.5 5764 99.1 15.6 8.4

Acceleration Test Constant Velocity 32 kph (20mph)

Motor Testing: Series vs. ParallelThe 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.

Parallel Series

Testing Progression

Major Milestones in TestingDate 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)

ModificationsMany 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

SuspensionModification was required in the rear suspension to handle additional loading from the batteries, and also to improve performance. The newsuspension 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 UtilitySnoWatt 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

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)

Anderson style disconnectfor high voltage

Warning lights to indicate connectedhigh voltage

High voltage contactor

Additional guards for mechanicalcomponents

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 bydropping in a different battery technology.

Future Work

•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

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:

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.