# US 8,569,666 B2 · Method for detecting the pan size in induction cooking hobs and induction cooking hob for carrying out such method

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- Number: US 8,569,666 B2
- Document ID: US8569666B2
- Status: Granted
- Kind: B2
- Application number: 12/687,366
- Filed: 2010-01-14
- Published: 2010-07-22
- Granted: 2013-10-29
- Earliest claimed: 2009-01-16
- Assignees: Whirlpool Corporation
- Applicants: Diego Neftali Gutierrez; Fabrizio Dughiero
- Inventors: Diego Neftali Gutierrez; Fabrizio Dughiero
- Web page: https://patentgrep.com/patent/US8569666B2

## CPC

- H05B 6/065: {using coordinated control of multiple induction coils}
- H05B 6/1254: {using conductive pieces to direct the induced magnetic field}
- H05B 6/1272: {with more than one coil or coil segment per heating zone}
- H05B 2213/05: Heating plates with pan detection means
- Y02B 40/00: Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

A method for detecting the pan size and/or position in induction cooking hobs comprises providing at least a sensing circuit associated to a magnetic field concentrator, particularly a ferrite bar, and assessing an electrical parameter thereof correlated to the variation of the magnetic flux.

## Claims

### Claim 1

A method for allocating power in induction cooking hobs having two or more laterally spaced, non-overlapping induction coils associated with a heating area for heating separate areas on a bottom surface of a cooking vessel, the method comprising:
sensing and assessing electrical parameters of sensing circuits associated with respective ones of the induction coils correlated to variation of magnetic flux; and
allocating power to the two or more induction coils based on the electrical parameters of the sensing circuits to balance heat provided to the bottom surface of the cooking vessel in order to minimize a temperature difference between the separate areas.

### Claim 2 (depends on 1)

The method according to claim 1, wherein a first of the induction coils is associated with a plurality of magnetic field concentrators wherein the sensing circuit associated with the first of the induction coils is associated with at least one of the magnetic field concentrators.

### Claim 3 (depends on 2)

The method according to claim 2, wherein each of the magnetic field concentrators is provided with a sensing circuit.

### Claim 4 (depends on 2)

The method according to any of the claim 2, wherein each magnetic field concentrator is provided with at least two sensing circuits placed at different positions.

### Claim 5 (depends on 2)

The method according to claim 2, wherein the plurality of magnetic field concentrators comprise ferrite bars.

### Claim 6 (depends on 1)

The method according to claim 1, wherein a first of the sensing circuits comprises a wire wrapped around a magnetic field concentrator.

### Claim 7 (depends on 1)

The method according to claim 1, wherein a first of the electrical parameters is at least one of an output induced mean voltage, a voltage peak-to-peak, a voltage signal phase, a voltage root means square, a voltage root mean square on a time interval around its peak value, or a combination thereof.

### Claim 8 (depends on 1)

The method of claim 1, further comprising:
balancing the supply of power to each coil of the two or more coils according to the following equations:
{
P
tot
=
total
⁢
⁢
power
⁢
⁢
to
⁢
⁢
be
⁢
⁢
supplied
⁢
⁢
to
⁢
⁢
the
⁢
⁢
pan
Covering_ratio
k
=
surface
⁢
⁢
of
⁢
⁢
coil
⁢
⁢
k
⁢
⁢
covered
⁢
⁢
by
⁢
⁢
the
⁢
⁢
pan
total
⁢
⁢
coils
⁢
⁢
surface
⁢
⁢
covered
∑
k
=
1
n
⁢
Covering_ratio
k
=
1
P
k
=
P
tot
·
Covering_ratio
k
.

### Claim 9 (depends on 1)

The method of claim 1, further comprising:
calculating a total power applied to the cooking vessel;
determining a covering ratio for each coil based on an area of each coil covered by the cooking vessel; and
allocating power for each coil based on the covering ratio.

### Claim 10

An induction cooking hob comprising:
two or more laterally spaced, non-overlapping induction coils associated with a heating area for heating separate areas on a bottom surface of a cooking vessel; and
a control circuit having sensing circuits for respective ones of the induction coils connected to the control circuit to provide electrical parameters correlated to variation of magnetic flux, the control circuit being configured to allocate power to the two or more induction coils based on the electrical parameters of the sensing circuits to balance heat provided to the bottom surface of the cooking vessel in order to minimize a temperature difference between the separate areas.

### Claim 11 (depends on 10)

The induction cooking hob according to claim 10, further comprising a plurality of magnetic field concentrators wherein the sensing circuits are associated with respective ones of the magnetic field concentrators.

### Claim 12 (depends on 11)

The induction hob according to claim 11, wherein two of the magnetic field concentrators are positioned at an angle of about 120° with reference to a coil center.

### Claim 13 (depends on 11)

The induction hob according to claim 11, wherein each magnetic field concentrator is provided with at least two sensor circuits placed at different positions.

### Claim 14 (depends on 11)

The induction hob of claim 11, wherein the plurality of magnetic field concentrators comprise ferrite bars.

### Claim 15 (depends on 10)

The induction hob according to claim 10, wherein a first of the sensing circuits comprises a wire wrapped around a magnetic field concentrator.

### Claim 16 (depends on 10)

The induction cooking hob according to claim 10, wherein said control circuit is further configured to balance the supply of power for each of the two or more coils according to the following equations:
{
P
tot
=
total
⁢
⁢
power
⁢
⁢
to
⁢
⁢
be
⁢
⁢
supplied
⁢
⁢
to
⁢
⁢
the
⁢
⁢
pan
Covering_ratio
k
=
surface
⁢
⁢
of
⁢
⁢
coil
⁢
⁢
k
⁢
⁢
covered
⁢
⁢
by
⁢
⁢
the
⁢
⁢
pan
total
⁢
⁢
coils
⁢
⁢
surface
⁢
⁢
covered
∑
k
=
1
n
⁢
Covering_ratio
k
=
1
P
k
=
P
tot
·
Covering_ratio
k
.

### Claim 17 (depends on 10)

The induction cooking hob according to claim 10, wherein said control circuit is further configured to:
calculate a total power applied to the cooking vessel;
determine a covering ratio for each coil based on an area of each coil covered by the cooking vessel; and
allocate power for each coil based on the covering ratio.