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UNH ECE 791 Senior Project I Design Proposal Presentation. Team. Members: Luke Vartuli Stephen Doran Doug MacMillan Advisor: Dr. Gordon Kraft. Problem Statement. Problem: Noise Emissions Cost of operation Solution: Electric snowmobile. Project Overview. - PowerPoint PPT Presentation
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UNH ECE 791
Senior Project I
Design Proposal Presentation
Team
Members:• Luke Vartuli
• Stephen Doran
• Doug MacMillan
Advisor:• Dr. Gordon Kraft
Problem Statement
Problem:• Noise• Emissions• Cost of operation
Solution:• Electric snowmobile
Project Overview
• Starting point => Polaris Snowmobile
• Breakdown of snowmobile
• Electric motor– Motor Theory
• Motor Control
• Pulse Width Modulation
• PWM circuit
• Power MOSFET’s
• Mounting bezels
• Battery type
• Battery mounting
• Timeline
• Budget
• Contributions
Starting Point
Donor Sled: 1996 Polaris Indy XLT
Breakdown of Snowmobile
Components Removed:• Engine• Exhaust• Fuel tank• Oil tank• Starting battery• Cooling system
Electric Motor
Specifications:• Mfg: General Electric• Model: 2CM6501Nameplate Ratings:• Voltage: 120VDC
• Armature Current: 167 A• Field Current: 10 APlace of Origin:• WWII Era B-29 Aircraft
Armature
• Main component of the DCMG
• Uses multiple Armature windings for conduction
• Undergoes Dynamo effect
Shunt DCMG
• Armature and Inter-poles are in parallel to the Main poles.
• As load changes only a fraction of the field will change.
• Safer, but has bad torque characteristics
Shunt Diagram
Armature
+
-
NS
Interpoles
LOAD
Windings
1 2 3 4 5 6 7 8 9 10 11 12 13 14
SIMPLEX WAVE WINDING
1516
Since the coils span every 3 commutator segments. This is
considered a simplex wave winding with a triplex commutator pitch.
The Commutator pitch is as follows….
Yc = (C ± m)/(P/2)WhereYc = Pitch of commutator
C = number of commutator segments
m = the plex of winding, or in context. The span of the coil from one segment to another. For instance since above winding is a triplex. m= 3
P= number of poles
The coil pitch for this unit is as follows….
Ys = S/P WhereYs = Coil pitchS = number of armature slotsP = number of poles
It is important that no matter the number you get you must round down to the next integer. If its 12.6 then Ys = 12. If its 10 then Ys = 10.
Single Element coil
Simplex Lap
Commutator
• “Assembly line for current transfer”
• As the commutator spins, current conducts from the brush (-) to the commutator bars the Load back to the Brush’s(+).
Inter-poles
• Maintains a neutral field flux over the commutator as the load changes.
• By having a neutral field flux over the commutator, this limits “sparking” on the commutator which then leads to pitting and damage. This will disrupt proper commutation.
Inter-poles at work!
Y-Axis
S NN
Full Load Magnetic field
No Load Magnetic field
S N
Full Load Magnetic field
No Load Magnetic field
Y-Axis
Time
Neutral- No Load and Full Load
No Load Neutral Full Load Neutral
No Inter-poles
With Inter-poles
Motor Control
How the motor will be controlled:• Vary armature current, fixed field• Pulse Width Modulation (PWM)• Power MOSFET’s
Pulse Width Modulation (PWM)
• Use PWM to control armature, fixed field• PWM controls power MOSFET’s• As duty-cycle increases, switches on longer,
motor spins faster
PWM circuit
Power MOSFET’s
Pros:• High current• Fast switching• Low resistance
Cons:• No protection from fly
back voltage• Get hot
Mounting Bezels
Key Components:• Bed plate• Motor• Motor bezel• Bearing Bezel• Clutch assembly• Orig. Motor Mounts
Battery Type
Flooded Lead Acid, Why?• Availability• Low cost• Ease of configuration• Ease of mounting• Ease of connection
Source: www.carbasics.co.uk/inside_car_battery.gif
Battery Mounting
Configuration: Series
Nom. Voltage: 120VDC
Mounting: Battery rack with top straps
Timeline
Budget
• Snowmobile: Donated
• Electric Motor: Donated
• Wire and misc. supplies: Donated
• Mounting Bezel: $200
• Batteries: $1000
• Pulse Width Modulator: $150
Contributions
Donations:• Snowmobile donated by Vincent Pelliccia• DC Motor donated by Kevin White• Wire and misc. electrical materials donated by Vartuli Electric, LLC
Support and Guidance:• Prof. Kraft• Prof. Hludik• Prof. Clark• Prof. Smith• Adam Perkins• Matt Borowski
Thank you for your time
DC MOTOR THEORY
• Same concept as AC Motor/Generators
• Utilizes carbon brushes for DC characteristics
Flemings right Hand rule
S
N
Conductor Movement
Field Flux
Current
+
_
Armature Physics
S
N
As the conductor changes direction, the current and voltage will also change
polarity
Armature Flux from Current
Simple Voltage production using a conductor and two magnets of
opposite polarity
Load
Commutation Diagram50 A50 A050 A50 A50 A
50 A 50 A
Rotation
+ Brush
100 Amps
Current from negative polarity
brush
Current from negative polarity
brush
Coi
l Cur
rent
Distance0
+50
-50
Armature Coils undergoing Ideal Commutation
Rotation
- Brush
Current going to positive polarity
brush
Current Going to positive polarity
brush
50 A50 A050 A50 A50 A
N S
Magnetic Field between two
magnets
SN +
Armature induced EMAG
Rotation
N SRotation
New Magnetic field due to combination
++
+
++
+
90
Neutral
F
Vector F repersents
MMF due to Main poles
Fa F0
F
New Neutral
Fa
Vector Fa represents
MMF due to armature
induced current
Due to the field MMF vector F and the armature MMF vector Fa combine at right angles to form the resultant field MMF vector
F0
Armature current
Compound DCMG
• Utilizes both series and shunt characteristics
• More common DCMG
Compund Diagram
ArmatureN S
InterpolesShunt Connection
Series Connection
LOAD
Series DCMG
• Poles, Inter-poles, and Armature all in series.
• Change in load is directly proportional to change in speed.
• Reduction in load can cause a “run-away” motor which will then lead to mechanical failure.
• High torque applications.
Series DCMG diagram
ArmatureNS
Interpoles
LOAD