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Critical Design Review

Critical Design Review. Ahmad Alawadhi Eric Willuweit Kegan Grimes Kyle Chessman Sean Flodberg. Team Iron Chefs. Eric. CDR Agenda. The Design Project Status and Goal. Eric. The Design. Eric. PDR Review. Sense (appropriate ferromagnetic) cookware.

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Critical Design Review

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  1. Critical Design Review Ahmad Alawadhi Eric Willuweit Kegan Grimes Kyle Chessman Sean Flodberg Team Iron Chefs Eric

  2. CDR Agenda • The Design • Project Status and Goal Eric

  3. The Design Eric

  4. PDR Review • Sense (appropriate ferromagnetic) cookware. • Turn on a PWM signal and LED indicator to corresponding coils. • Test multiple types of sensors • Photodiodes, induction, infrared, and pressure mapping • One coil sub-system Eric

  5. Concept Overview • Adjusted approach • Hardware and Software Interaction • Sub-systems • Sensor • Power Stage • Gate Stage • Feedback Eric

  6. Adjusted approach • Utilize seven smaller copper coils in place of a large single coil. • Sense cookware’s location on the range via induction sensing. • Supply power to the coils that sensed the cookware. Eric

  7. System Flow Diagram Eric

  8. Preliminary Sub-system Implementation • Systems • Indicator LEDs • Sensors • Copper coils Eric

  9. Current Sub-system Implementation • Systems • Indicator LEDs • Induction sensing • Power Supply • Resonant Circuit • Gate Driver • Microcontroller Eric

  10. LED Indicator Sub-system Kegan

  11. LEDs indicate which coils are being supplied with power. • LEDs on temperature knobs lit with same color LED as the powered coils to display which cookware the knobs correspond to. Kegan

  12. LED Location Each coil has at least five LEDs LEDs on LEDs off Kegan

  13. LED Use Cases LEDs on LEDs off Kegan

  14. LED Use Cases LEDs on LEDs off Kegan

  15. LED Use Cases LEDs on LEDs off Kegan

  16. Sensor Sub-system Kegan

  17. Sensor Sub-system Circuit • Coils are also used as induction sensors. • Placing ferromagnetic cookware above the coil, its measurable impedance changes . • Impedance change, affects measurable power. Kegan

  18. Sensor Sub-system Circuit A bridge rectifier and low pass filter turns the AC signal across the coil into a DC signal. Kegan

  19. Sensor Sub-system • The DC signal is fed into an analog to digital converter to be processed by the microcontroller. • When the voltage across the coil drops below a threshold, the LED turns on and a varying frequency PWM is initiated. Kegan

  20. Testing Potential Sensors • Photodiodes • Induction sensing • Infrared LEDs • Pressure sensing / Mapping Kegan

  21. The “Transitron” • JB Saunders • A three terminal device • Light enters the base region and causes electrons to be injected into the emitter. Kegan

  22. Transitron Evaluation • Voltage change of only ~10mV • Fed into an Op-Amp • Amplified signal fed to ADC on the Arduino Uno (used for demo) • Turned on the LED when transitron is covered Kegan

  23. Transitron Pros and Cons • Pros • Inexpensive • Availability • Easy Implementation • Cons • Requires an amplifier • Unreliable • Cover with ANY object and the coil supplies a magnetic field Kegan

  24. Consensus: No thank you, transit-tron Kegan

  25. Total Circuit Simulation Sean

  26. Sean

  27. Power Supply Sean

  28. Input Power • 120VAC at 60Hz • Common mode choke • Bridge Rectifier Sean

  29. Gate Circuit Sean

  30. Gate Drivers • High power IGBTs Sean

  31. Power IGBTs • ON Voltage – 15V • Supplied from gate driver • Rated For: • 1200V • 40A • Reverse conduction diode • Heat: • Cool using an aluminum heat sink Sean

  32. Resonant Tank Sean

  33. Matching Impedance • LC Tank: • Resonant Frequency • Matches switching frequency with resonant frequency to maximize power output SW Sean

  34. Sean

  35. Testing Hardware • Variable Auto-Transformer • Audible IGBT switching • Cast iron pan warmed up • Observed Risks • Current regulation • 8 fuses blown • Capacitor sustaining charge Sean

  36. Microcontroller Kyle

  37. HW-SW Bridge • TOPREF – Top reference • SWREF – Feedback • Compare the two references PWM Kyle

  38. Texas Instruments C2000 • Output: • Seven PWM signals for the final design • A variable frequency PWM to find resonance of cookware and contents • LED power to covered coils • Input: • Read analog signals through ADC from the feedback circuit and adjust PWM output accordingly • Additional: • Check resonant frequency approximately every 10 seconds Kyle

  39. Results Kyle

  40. Induction Sensor • No cookware: 3.2VDC • With 15in cast iron pan over coil: 1.77VDC • With 6in aluminum pot over coil: 1.69VDC • Set ADC threshold to turn on LED and supply PWM only for cast iron pan Kyle

  41. Coil without cookware Kyle

  42. Coil with 15” Cast Iron Pan Kyle

  43. Prototype Board Common Mode Choke IGBTS Driver Circuit Resonant Tank Bridge Rectifier Ahmad

  44. Analog Feedback Circuit Ahmad

  45. Complete One Coil System Ahmad

  46. Future Milestones • Finish one-coil subsystem • Design seven-coil system • Design software to accommodate seven coils • Integrate subsystems Ahmad

  47. Potential Risks • Magnetic Field • Connecting to mains • Probing High voltages • High current pollution back to the auto-transformer Ahmad

  48. Spent Budget Ahmad

  49. Preliminary Parts List Ahmad

  50. Updated Schedule Ackhmad

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