Transcript KyleS-311Presentation

Wicked Kool WRX Startup
Circuit
Sam Schoofs
Kyle Schlansker
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Goals
To design a circuit for Kyle’s Subaru WRX
– It must turn on an inverter and computer inside the
car when the car is turned on.
– It must turn off both the inverter and computer when
the car is turned off.
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Specific Circuit Goals
The inverter will power the computer.
The computer will be used to play music
(in the future, DVDs, games, etc).
The computer should be turned on 30
seconds after the inverter is turned on to
allow the inverter to fully charge.
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Block Diagram
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Switching
Two switches needed to be designed.
– The first had to turn on the inverter when the car
was started.
– The second had to turn the computer on 30 seconds
after the inverter was turned on.
A Basic Stamp 2 microprocessor will be used
to control the switching of the circuit.
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Switch Options
For the inverter switch:
– Solenoid switch
– BJT switch
– MOSFET switch
For the computer switch:
– Photo FET Optocoupler
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Schedule
Plan of Attack
– Brainstorm different methods of implementing our
circuit goals.
– Select the optimal method.
– Find parts that meet our design criteria.
– Simulate our circuit, with cadence, using the chosen
parts.
– Test a preliminary circuit in the lab.
– Implement working circuit in the future.
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Switch Selection
The solenoid was more complicated and
prone to mechanical failure.
The BJT was not practical because of the
limited source current from the
microprocessor.
The MOSFET could handle the amount of
current and was easily implemented with
the microprocessor.
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Switch Parameters
The inverter would need 40 amps DC
(max) sustained current.
A low drain-source resistance was needed
to minimize the voltage drop from the car
battery to the inverter.
The MOSFET needed to be able to
saturate at a VGS of around 8 V and cutoff
at 0 V.
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MOSFET Selection
Googled for hours
Asked Chuck for
search
recommendations
Searched Newark’s
website until one
could be found to
meet the
requirements.
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Computer Switch
A photo FET
optocoupler was
selected to ensure
that no feedback
could destroy the
microprocessor.
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Circuit Schematics
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High Current Switch
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Simulation Output for MOSFET Gate
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Safe Physical Implementation
Op-Amp
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Unsafe Physical Implementation
Inverter-Battery hookup
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Full “High Power” Test Setup
Car Battery
Our version of
“Chassis Ground”
Scott’s 1337 80mm
heat sink and fan
(thanks 319!)
Digital Readout of
Battery Voltage
(12.2 V)
Test motherboard
(Scott’s “strange”
Tyan trinity)
Motherboard Power
Switch
Op-Amp circuit
Photo FET Optocoupler
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The Next Step
Put both switches on a PCB with BS2
– The PCB is already made.
– The code for the BS2 is already written.
Install the setup in the car
– The inverter and computer will go in the trunk.
– The PCB will be mounted near the drivers
seat.
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