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Preliminary Design Review

Team Iron Chefs

Ahmad AlawadhiEric WilluweitKegan GrimesKyle ChessmanSean Flodberg

OverviewProject ObjectiveBackgroundApproachSub-system ImplementationMember RolesScheduleContingency Plan

Chessman

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

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

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

Approach Utilize smaller copper coils in place of the large

single coils. Sense cookware’s location on the “zone-free”

range. Supply power to the coils that sense the

cookware.

Chessman

Inputs and Outputs

Alawadhi

System Flow Diagram

Alawadhi

Sub-system Implementation Systems

Indicator LEDs Copper coils Sensors

Alawadhi

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

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

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

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

Testing Potential Sensors Photodiodes Induction sensing Infrared LEDs Pressure sensing /

Mapping

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

Amplifier Circuits Driver Amplifier

A class D Amplifier Completely digital Input from the PWM

supplied from theMCU

Energy efficient

High Gain Amplifier Op-amp with feedback

circuit Could also use a transistor

combination circuit

MCUPWMSignal

Coils

IGBT

IGBT

Grimes

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

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

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

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

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

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

Member RolesTasks Ahmad

Alawadhi

EricWilluweit

Kegan Grimes

KyleChessman

SeanFlodberg

Software Design

MCUFeedback

DebuggingHardware Design

SensorsDrivers/

AmplifiersPower SupplyCopper

coilsDebugging Flodberg

Timeline

Flodberg

QUESTIONS