Simulation Beyond Volts and Amps (Part 3)

In Part 1 and Part 2 of this post series I described some of the non-electrical behaviors of an incandescent lamp and fuse, and then explained how these behaviors might be accounted for in a simulation model. Now it’s time to combine these two models, with a handful of others, to analyze the thermal behavior of a basic automotive emergency flasher system. Here is my circuit’s schematic:

   lamp_circuit_graphic4

 

 Though a simplified version of an actual flasher system, this circuit contains the main system elements: four incandescent lamps representing one at each corner of the vehicle; a length of wire connecting each lamp to the fuse box; the flasher system fuse; a length of wire connecting the fuse box to the car’s battery; a switch representing the flasher on/off switch inside the car; and the battery. Note that the switch model allows me to control on/off switching using a simple digital clock. There are certainly other ways to model a flasher system, but this circuit is adequate for our discussion.

To add a bit of realism to the component parameters in my system, I dusted off the maintenance repair manual for a Jeep Cherokee I used to own and browsed the wiring diagram for the emergency flasher circuit. Here is what I found:

  • Light bulbs: Type 2057 with an “on” (i.e. hot) filament resistance of 6.1Ω. Rules of thumb estimate a lamp’s on resistance to be on the order of 10x greater than the cold filament resistance — a parameter required by the lamp model. Using this rule, I set each lamp’s cold resistance to 600mΩ.
  • Wire gauges and lengths: For wire size I used AWG12 between the battery and fuse box, AWG18 between the fuse box and the front flashers, and AWG20 between the fuse box and rear flashers. For wire length, two meters of wire between the battery and fuse box, and three meters between the fuse box and each of the lamps (yes…all wire lengths are simply estimates based on my knowledge of the Jeep’s size – the wiring diagrams do not give wire lengths).
  • Fuse: According to the wiring diagram, my fuse must have a 15 amp minimum blow current. I left the element melting point at the model’s default: 400 °C.
  • Battery: I left the battery model’s parameters at their default values: 12.6 VDC open circuit voltage; 15mΩ effective internal impedance.

After assigning these design parameters, I used SystemVision to analyze my flasher circuit’s performance against the following specification ranges:

  • Flashes per minute (FPM): 70 – 100
  • Duty cycle (DC): 35% – 55%

Along with taking a general look at my circuit’s thermal profile, I wanted to see if I really need a 15 amp fuse for circuit protection. I will show you the results in my next blog post.

 

Post Author

Posted November 17th, 2010, by

Post Tags

, , ,

Post Comments

No Comments

About Mike Jensen's Blog

Views, insights, and commentary on mechatronic system design and analysis. Mike Jensen's Blog

Comments

Add Your Comment

Archives

May 2014
  • SystemVision 5.10.3
  • March 2014
  • IESF 2014: Military & Aerospace
  • Engineering Oops!
  • Big Engineering
  • January 2014
  • SystemVision Model Wizard
  • December 2013
  • SystemVision 5.10.2
  • Modeling: An Engineer’s Dilemma
  • October 2013
  • What is Your Legacy?
  • September 2013
  • Automotive IESF 2013
  • July 2013
  • Simple Design Solutions
  • June 2013
  • SystemVision 5.10
  • May 2013
  • Engineering Muscle Memory
  • EDA vs. Windows 8
  • March 2013
  • VHDL-AMS Stress Modeling – Part 3
  • January 2013
  • VHDL-AMS Stress Modeling – Part 2
  • VHDL-AMS Stress Modeling – Part 1
  • December 2012
  • Practice! Practice!
  • November 2012
  • Sharing Tool Expertise
  • October 2012
  • Preserving Expertise
  • Virtual Prototyping — Really?
  • Innovations in Motion Control Design
  • September 2012
  • Game Changers
  • Do We Overdesign?
  • August 2012
  • Tsunami Remnants
  • July 2012
  • A New Look at Device Modeling
  • SystemVision 5.9
  • June 2012
  • Veyron Physics
  • May 2012
  • Rooster Tail Engineering
  • April 2012
  • Automotive IESF 2012
  • Teaching and Learning CAN Bus
  • March 2012
  • Analog Modeling – Part 6
  • Analog Modeling – Part 5
  • Analog Modeling – Part 4
  • February 2012
  • Analog Modeling – Part 3
  • Analog Modeling – Part 2
  • January 2012
  • Analog Modeling – Part 1
  • Connecting Tools and Processes
  • December 2011
  • Turning-Off and Tuning-In
  • Use vs. Experience
  • Analyzing the Big Picture
  • November 2011
  • Simulating for Reliability
  • October 2011
  • SystemVision 5.8
  • VHDL-AMS Model Portability — Fact or Fiction?
  • September 2011
  • IESF 2011 Moves to Frankfurt
  • Simulation Troubleshooting
  • August 2011
  • Qualities of VHDL-AMS Quantities
  • Military & Aerospace IESF 2011
  • Touring Johnson Space Center
  • July 2011
  • Engineering versus Science
  • June 2011
  • System Reengineering
  • May 2011
  • Integrating Hardware and Software Design
  • Engine Remote Start
  • Integrated System Design
  • Simulation Experiments (Part 3)
  • April 2011
  • Automotive IESF 2011
  • Pushbutton Cars
  • System Simulation with FEA-Base Motor Models
  • March 2011
  • Simulation Experiments (Part 2)
  • Simulation Experiments (Part 1)
  • Japan: Patience and Grace Amid Disaster
  • Top Gear = Driving Fun
  • February 2011
  • Buoyancy
  • Ideas in Motion
  • January 2011
  • The Mechanical Half of Mechatronics
  • Detroit Auto Show
  • Signal-flow vs Conserved System Modeling
  • SystemVision 5.7…Ready, Set, Go!
  • December 2010
  • SystemVision and Windows 7
  • Friction Vacation
  • Simulation Beyond Volts and Amps (Part 4)
  • November 2010
  • Simulation Beyond Volts and Amps (Part 3)
  • Simulation Beyond Volts and Amps (Part 2)
  • Simulation Beyond Volts and Amps (Part 1)
  • October 2010
  • SAE Convergence Recap (and an Unexpected Surprise)
  • VHDL-AMS Black Belt
  • Converging on SAE Convergence
  • System Design vs System Repair
  • September 2010
  • What’s the “AMS” in VHDL-AMS?
  • How Sensitive is Your System?
  • Do You Trust Your Simulator?
  • August 2010
  • What’s in a SPICE Model?
  • Cycling + Gravity = Pain
  • NI Week: Fun for Engineers
  • June 2010
  • Are You a Flexible Thinker?
  • VHDL-AMS and Switch Hysteresis
  • May 2010
  • VHDL-AMS Revisited
  • Segway to U3-X
  • Atomic Glue
  • March 2010
  • IESF Recap
  • February 2010
  • IESF is Coming…
  • System Level HDL-topia
  • January 2010
  • Mastering Design Abstraction
  • The Joy of Disassembly