Air-Fuel Ratio Control in Spark-Ignition Engines - PowerPoint PPT Presentation

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Air-Fuel Ratio Control in Spark-Ignition Engines

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Air and the fuel enter the carburetor, then through the engine and ... Root Locust Diagram. Design of Lead Compensator. Required Formula. Gc(s)= (s z) / (s p) ... – PowerPoint PPT presentation

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Title: Air-Fuel Ratio Control in Spark-Ignition Engines


1
Air-Fuel Ratio Control in Spark-Ignition Engines
  • Presented to
  • Dr. Riadh Habash, Fouad F. Khalil
  • Presented by
  • Ziad El Kayal, Hassan Fakih
  • Umar Qureshi, Marc Topalian

2
How it Works
  • Air and the fuel enter the carburetor, then
    through the engine and finally past a senor
  • Using a sensor to measure the oxygen content of
    the engine's exhaust, the system keeps the
    fuel-air ratio very close to the proportion for
    chemically perfect combustion

3
References
  • Air-Fuel Ratio Control in Spark-Ignition Engines
    Using Estimation Theory Chen-Fang Chang,
    Nicholas P. Fekete, Alois Amstutz, and J. David
    Powell
  • Development of a Transient Air Fuel Controller
    for an Internal Combustion Engine Stewart P.
    Prince
  • Digital Control of an Automobile Engine Air-Fuel
    Ratio System Martin J. Dubois, Robert P. Van
    Til, Nicholas G. Zorka
  • Individual Cylinder Air-Fuel Ratio Control with
    a Single EGO Sensor Jessy W. Grizzle, Kelvin L.
    Dobbins, and Jeffrey A. Cook
  • Design and Development of an ECU and its
    Air-Fuel Ratio Control Scheme Myomgho Sunwoo,
    Hansub Sim and Kangyune Lee

4
Requirements
  • The controller must keep a fuel to air ratio of
    114.7 (0.068)
  • The overshoot at the output must not be greater
    than 16.
  • The settling time must be less than or equal to
    10 seconds.

5
Required Characteristic Equation
  • From the IEEE article, the maximum overshoot
    required is 16 and the maximum settling time was
    10 seconds.
  • Required Characteristic Equation
  • s2 2wn?s 2wn
  • Through calculation we found
  • ? (damping factor) 0.5
  • wn0.8 rad/s
  • Therefore, set s equal to zero and find the
    poles, using the quadratic equation
  • s1-0.4 0.4v3 i
  • s2-0.4 - 0.4v3 i

6
Open Loop Transfer Function
  • We needed to find a transfer function we could
    use to plot a root locus diagram
  • We found the open loop transfer function of our
    block diagram to get the following formula
  • (0.5t2Td 0.5t1Td)s Td
  • T1t2s2 (t1 t2)s 1
  • Using constants from IEEE references we were able
    to plot the following root locus diagram
  • The diagram allowed us to find the roots and
    poles of the transfer function
  • From the diagram we were able to design the lead
    compensator

7
Root Locust Diagram
8
Design of Lead Compensator
  • Required Formula
  • Gc(s) (sz) / (sp)
  • The zero is found from the previous calculations,
    z 0.4
  • Use Root Locus method to find the value of the
    pole.
  • Draw straight lines from s1 to all the poles and
    zeros found on the root locus
  • No need to use s2 because it is just a complex
    conjugate
  • Find the angle at which the pole is located
  • ?1 177 degrees
  • ?2 50 degrees)
  • ?3 5 degrees)
  • ?4 1 degree
  • ? 19 degrees
  • Using ? -?1 -?2 -?3 -?4 -?d-180 degrees
  •   ?d65 degrees
  • Using this we were able to find the pole which we
    used to design our lead compensator
  • Gc(s) (s0.4) / (s0.6)

9
Open Loop Transfer Function Diagram
10
Closed Loop Transfer Function Diagram
11
Simulink Design
12
Simulink Closed Loop Transfer Function Diagram
13
Conclusion
  • Through research, we were able to design a
    controller to regulate the fuel to air ration in
    a spark-ignition engine with an overshoot of 11
    and a settling time of 10 seconds.
  • We were able to accomplish the emission standards
    by adjusting the fuel to air ratio required by
    the IEEE paper.
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