Preliminary Design Review Team Iron Chefs Ahmad Alawadhi Eric
Willuweit Kegan Grimes Kyle Chessman Sean Flodberg
Slide 3
Overview Project Objective Background Approach Sub-system
Implementation Member Roles Schedule Contingency Plan Chessman
Slide 4
Project Objective The goal of our project is to innovate the
existing induction cooktop design with designated cooking locations
and creating a zone free cooking range. Chessman
Slide 5
Existing Cooktops Cook tops use one large copper coil for each
designated zone. The copper coils create a magnetic field which
induces eddy currents into the cookware above it. These small
currents heat the cookware through resistance of the material.
Chessman
Slide 6
Background Cookware used must be a ferromagnetic material as
the heat produced arises from Eddy Currents and the resistance
caused by the skin layer of the metal. Cookware must be flat-
bottomed to maintain efficiency. Universal Symbol for induction
cooking Chessman
Slide 7
Approach Utilize smaller copper coils in place of the large
single coils. Sense cookwares location on the zone-free range.
Supply power to the coils that sense the cookware. Chessman
Slide 8
Inputs and Outputs Alawadhi
Slide 9
System Flow Diagram Alawadhi
Slide 10
Sub-system Implementation Systems Indicator LEDs Copper coils
Sensors Alawadhi
Slide 11
Indicator LED Sub-system 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 coils the knobs
correspond to. Willuweit
Slide 12
Copper Coils Sub-system Power supplied through the IGBTs PWM
signal generated from the MCU Current transformer to feedback
circuit To optimize power transfer Willuweit
Slide 13
Coil Construction 3 inch flat copper coils Litz copper wire
Small gauge insulated copper wire wound like a rope into a larger
gauge wire for transporting high frequency currents Take advantage
of the skin effect used by transmission lines Willuweit
Slide 14
Sensor Sub-system Sensors change resistance when cookware is
placed above them, causing a change in voltage. High gain amplifier
boosts the small signal to be noticed by the microcontroller.
Willuweit
MCU - Microcontroller Output at least seven PWM signals for our
desired hexagon shaped design. Read analog signals from the
feedback circuit and adjust PWM output accordingly Controls LEDs
MCU Requirements PWM outputs for each coil A/D converters for each
coil feedback Possible Choices: ARM A series ATXmega64
Willuweit
Slide 17
Amplifier Circuits Driver Amplifier A class D Amplifier
Completely digital Input from the PWM supplied from the MCU Energy
efficient High Gain Amplifier Op-amp with feedback circuit Could
also use a transistor combination circuit MCU PWM Signal Coils IGBT
Grimes
Slide 18
The Cookware, the Coil and the Capacitors (LC Tank) The coils
act as an inductor When placed in series with capacitors, the two
form an LC circuit also known as an LC Tank Grimes
Slide 19
Feedback Circuit Step-down transformer to supply 5V back to the
MCU Measures analog voltage signal from LC tank MCU adjusts
frequency of the PWM signal supplied to the IGBTs Frequency will
begin high (60kHz) and decrease down to potentially 19kHz When the
voltage amplitude peaks and is measured by the MCU, the frequency
is maintained and the optimum power transfer has been reached
Grimes
Slide 20
Power Supplied with 120/240 AC voltage from the wall outlet
Rectified to a DC voltage of 5V and 15V for the MCU and analog
components Transform the 15V to 325V DC to be supplied to the IGBTs
PWM signal controls the on/off state of the transistors creating an
effective square wave AC signal. Grimes
Slide 21
Power Transfer The alternating square wave from the IGBTs
creates an alternating magnetic field in the copper coils The field
is directed into the cookware, inducing eddy currents Each
individual coil will create a portion of the overall field
necessary to heat the cookware The number of coils needed varies
with the cookware size Grimes
Slide 22
Power Requirements With a 22 cm diameter iron pot on top of
range, the system will deliver approximately 2500 watts At an input
of 60Hz Frequency supplied to the coils is 25kHz At a 100
peak-to-peak current to the coils This would be divided between
seven coils accordingly Flodberg
Slide 23
Feasibility Materials Availability/ Creation of copper coil
windings What kind of surface? Existing surfaces are Ceran
Combination of glass and ceramic Sensors sensitivity to temperature
Power Ability of small coils to generate energy equivalent to the
large coils Flodberg
Slide 24
Member Roles TasksAhmad Alawadhi Eric Willuweit Kegan Grimes
Kyle Chessman Sean Flodberg Software Design MCU Feedback Debugging
Hardware Design Sensors Drivers/ Amplifiers Power Supply Copper
coils Debugging Flodberg