Critical
Design
Review
Team Iron Chefs
Ahmad Alawadhi
Eric Willuweit
Kegan Grimes
Kyle Chessman
Sean Flodberg
1
Eric
2
CDR Agenda
 The
Design
 Project
Status and Goal
Eric
The Design
3
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
LED Indicator
Sub-system
10
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
LEDs on
Each coil has at
least five LEDs
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
Sensor
Sub-system
16
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
Total Circuit
Simulation
25
Sean
26
Sean
Power Supply
27
Sean
28

Input Power



120VAC at 60Hz
Common mode choke
Bridge Rectifier
Sean
Gate Circuit
29
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
Resonant
Tank
32
Sean
33
 Matching
 LC

Impedance
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

Current regulation
8

Risks
fuses blown
Capacitor sustaining charge
Sean
Microcontroller
36
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



LED power to covered coils
Input:


A variable frequency PWM to
find resonance of cookware
and contents
Read analog signals through
ADC from the feedback circuit
and adjust PWM output
accordingly
Additional:

Check resonant frequency
approximately every 10 seconds
Kyle
Results
39
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 autotransformer
Ahmad
48
Spent Budget
Item
Quantity
Price
1200V, 40A, IGBTs
4
$23.84
NPN Transistor
3
$1.02
PNP Transistor
2
$2.14
Voltage Regulator
2
$4.04
Burton Single Coil Stove
1
$79.95
Photo-sensors
4
~$4.50
Assorted Capacitors and Resistors
NA
Harvested
Half bridge High voltage Driver Chip
3
$6.45
Total
$121.94
Ahmad
49
Preliminary Parts List
Item
Quantity
Cost
Litz Wire – 32AWG, ~900 strand
~200ft
Currently uncertain
TI-C2000
1
$0.00 - Given
High Voltage Capacitors
~20
~$100.00
Ferrite Core Wound Inductors
~10
~$60.00
PCB
2
~$80.00
Fuses
~10
$20.00
Ceran Top
1
~$100.00
Frame
1
Currently uncertain
Total
~$400.00
Ahmad
Updated Schedule
50
Ackhmad
Member Roles
Tasks
Ahmad
Alawadhi
Eric
Willuweit
51
Kegan
Grimes
Kyle
Chessman
Sean
Flodberg
Software
Design
C2000
Primary
Feedback
Debugging
Hardware
Design
Secondary
Sensors
Power
Supply
Gate
Circuit
Resonant
Circuit
Debugging
Ahmad
52
QUESTIONS?
Ahmad