Transcript ME 495 EV - University of Washington

University of
Washington
Electric Pontiac Fiero Project
Presented by Eric Yost
Problem Statement:
General: To convert a gas powered ’88
Pontiac Fiero into an electric vehicle
able to accelerate from 0–60 MPH in
less than 5 seconds.
Specific: Design and integrate the drive
train that best meets the requirements
of the customer
Design Problems:
• Transmission
• No transmission
Design Problems:
Number and type of motors:
Dual 8” motors
Single 9” motor
Permanent Magnetic Motors
Design Problems:
Connecting the motors:
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PD Belt
Pulley and Belt
Two-gears
Three-Gears
Chain
Current Design:
Simulation:
Will be used to:
– Determine manual transmission shift points for
maximum acceleration
– Determine manual transmission shift points for
everyday commuting
– Analyze specific components of the vehicle
Simulation Block Diagram:
Simulation Components:
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Driver
Controller
Motors
Coupling System
Transmission
Car Dynamics
Driver:
Assumes pedal to the metal
Controller:
Simulates the electric system
Controller II:
Equation 1:
• V = I R + Ke ω
– V: Voltage
– I: Target Current ≈ 2000 amps
– R: Motor Resistance ≈ 0.02 Ohms
– Ke: Motor Constant ≈ 0.25
– ω: Motor’s Angular Velocity
This voltage is capped at 196V
Equation 2:
• I = (V – Ke ω) / R
This current is divided and fed to each motor
Controller III:
Back EMF
Motor:
Equation for torque:
Coupling System:
Connects the two motors together
Transmission:
Multiplies the torque and divides the RPM by the
gear ratio
Car Dynamics:
Turns the applied torque into an acceleration and
velocity
Car Dynamics II:
Equations for Car Dynamics:
– Force Equation:
– Power Equation:
Ideal Simulation Results:
Force Equation:
0-60 Time: 2.318s
Ideal Simulation Results:
Power Equation:
0-60 Time: 2.318s
More Realistic Simulation Results:
Force Equation:
0-60 Time: 4.170s
More Realistic Simulation Results:
Power Equation:
0-60 Time: 4.170s
Future Addition:
Tire Slippage
Two ideas of how to model tire slippage:
– Realistic approach: If the torque is too high, the tires slip
– Ideal approach: The torque is capped before the tires can slip
Inaccuracies:
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Motor calculations
No tire slippage
Efficiencies
Drag constants
Modeling the driver
Questions?