WO2017093168A1

WO2017093168A1 - An inductive coil unit

Info

Publication number: WO2017093168A1
Application number: PCT/EP2016/078960
Authority: WO
Inventors: Hilmi Volkan Demir; Emre UNAL; Erdal GONENDIK; Veli Tayfun KILIC; Namik Yilmaz; Metin OZTURK; Ulas OKTAY
Original assignee: Arcelik Anonim Sirketi; Innovel Danismanlik Ve Imalat Sanayi Ticaret Limited Sirketi
Priority date: 2015-12-01
Filing date: 2016-11-28
Publication date: 2017-06-08

Abstract

The present invention relates to an inductive coil unit (1) that is suitable to be used in induction heating cookers especially in all-surface induction cookers comprising a top plate (2) whereon cooking containers suitable for induction heating are placed, the inductive coil unit (1) comprising a plurality of adjacent coils (S1, S2, S3,...) that are produced from conductive wire or wires coated with non-conducting material, that are driven by one or more than one power source with an electric current of the same frequency and that magnetically interact with each other.

Description

AN INDUCTIVE COIL UNIT

The present invention in particular relates to an inductive coil unit suitable to be used in all-surface induction heating cookers.

In the state of the art, inductive coils used for wireless power transfer especially for induction heating are known. In these embodiments, power is created with the joule effect on the resistance produced as a result of the penetration depth determined by the frequency of the alternative currents of the electromagnetically inducted eddy currents of a coil generating high frequency magnetic field on a conductive metal cooking container (pot, pan etc.) having ferromagnetic features. The desired power adjustment for the suitable cooking container can be realized by changing the frequency of the alternative current. In order to use an induction heating cooker, the container desired to be heated has to be electrically conductive and produced from low density carbon steel, cast iron and magnetic inoxidizable materials with ferromagnetic features.

In the induction heating cookers, a certain number of coils are positioned under a glass surface so as to form the heating surface. In the state of the art there are a large number of embodiments wherein the coils are positioned in various configurations. In these embodiments, one or more than one coil designed to be one within the other at the regions determined by serigraphy on the glass surface heats a single cooking container. One of the problems encountered in the state of the art is to form coil structures that accommodate best with the cooking container that are produced in very different diameters and shapes and from different materials.

Another problem with the state of the art induction heating cookers is the necessity to operate the high power and large diameter coils together with smaller diameter coils in the most efficient manner. Moreover, as the size of the cooking container increases, the power to be transferred to the cooking container also increases. For example, if the power to be transferred per unit cooking container is desired to be increased then the number of coils also has to be decreased. On the contrary, if the position and geometry of the cooking container is desired to be detected on the entire surface, lower amount of power can be provided to small diameter cooking containers since the number of coils has to be decreased this time. One of the most important problems encountered in optimizing these values is the loss generated in the coils especially by high powers and thermal management.

In the state of the art, one of the important problems is that the base of the cooking container cannot be heated homogeneously in especially circular coil structures since a certain region at the base of the cooking container is heated, the middle portion of the coil windings being the center, which is also known as the “corona effect”.

One of the most important problems in all-surface embodiments developed and formed by using more than one coil instead of a single coil, is to optimize the magnetic coupling between the coils. In the state of the art embodiments, coil solutions with generally circular or quadrilateral coils arranged side by side are used. Using circular solutions leads to the corona effect and also causes the magnetic coupling between coils to be low. On the other hand, while the solutions with quadrilateral coils are the most suitable solution with regards to magnetic coupling, these solutions can be weaker in transferring power to small diameter pots.

In the induction heating cookers wherein the all surface is heated, in the case the adjacent coils operate at the same time, the efficiency of the cooker decreases and the cooking container thereon can be heated by consuming more power. Moreover, since more current is needed in order to heat the cooking container as required, electrical elements resistant to more current are used in the power circuit and thus production costs increase. In order to prevent this, induction heating cookers are produced wherein the distance between the coils is longer and/or the geometry of the coils is circular so that the coils affect one another less.

In the state of the art International Patent Application No. WO2014030315, the coils are formed in circular shape so that the effect of coils on one another that operate side by side at the same time is decreased, providing minimum adjacent side length.

In the state of the art European Patent Applications No. EP1527463 and EP2693837, a coil configuration is formed so that current flows in only the reverse direction and a constant 180 degree phase difference is created.

In the state of the art United States Patent No. US6498325, the coils are connected in parallel or series and are driven as a group. Although the coils are explained to be arranged side by side in reverse phase, the phase difference is constant and unchangeable and the side by side coil group always operates together.

The aim of the present invention is the realization of an inductive coil unit suitable to be used in induction heating cookers, especially in all-surface induction cookers.

The inductive coil unit realized in order to attain the aim of the present invention, explicated in the first claim and the respective claims thereof, comprises a plurality of coils that are adjacent to one another, that are driven by electric current in the same frequency and that magnetically interact with each other, and at least one of the coils is driven by an electrically different phase than the other adjacent coil.

In an embodiment of the present invention, at least two adjacent coils are driven by two separate power sources that apply current in 180° different phases or by a single power source.

In another embodiment of the present invention, the inductive coil unit comprises at least four coils that have windings with quadrilateral shape with rounded corners wherein each one is driven by a current in 180° different phase than the adjacent coil.

In another embodiment of the present invention, the coils are arranged on the top plate plane of the induction heating cooker, in alignment on two axes that are vertical to one another, so as to cover the entire top plate surface and the adjacent coils are driven with 180° phase difference.

In another embodiment of the present invention, each coil array on the top plate of the induction heating cooker is driven by a separate power source.

In another embodiment of the present invention, the coils are arranged on the top plate plane of the induction heating cooker, with their centers to be three cornered – trigonal, and the coils are driven respectively by 0°, 180° and 120° electrical phase difference and preferably by separate power sources.

In another embodiment of the present invention, the inductive coil unit comprises the coils that surround a center coil driven by a current with 120° phase difference and that are driven by currents with respectively 0° - 180° - 0° - 180° - 0° - 180° phase differences.

In another embodiment of the present invention, the inductive coil unit comprises adjacent coils, at least one of which has a different number of windings and/or winding shape.

The inductive coil unit realized in order to attain the aim of the present invention is illustrated in the attached figures, where:

Figure 1 – is the schematic view of the inductive coil unit situated on the top plate of an induction heating cooker.

Figure 2 – is the schematic view of the inductive coil unit composed of two coils that are driven at different phases by separate power sources.

Figure 3 – is the schematic view of the inductive coil unit composed of two coils that are driven at different phases by the same power source.

Figure 4 – is the schematic view of the inductive coil unit composed of four coils having quadrilateral windings with rounded corners.

Figure 5 – is the schematic view of the coil arrays fed by separate power sources in (X) direction on the plane of the top plate of an induction heating cooker.

Figure 6 – is the schematic view of the coil arrays fed by separate power sources in (Y) direction on the plane of the top plate of an induction heating cooker.

Figure 7 – is the schematic view of the inductive coil unit composed of three coils arranged in trigonal form and the diagram showing the currents applied to the coils in different phases.

Figure 8 – is the schematic view of the inductive coil unit composed of the coils in hexagonal form surrounding a center coil.

Figure 9 – is the schematic view of the inductive coil unit composed of three coils having different number of windings and the diagram showing the currents applied to the coils in different phases.

Figure 10 – is the schematic view of the inductive coil unit composed of three coils having different winding shapes.

The elements illustrated in the figures are numbered as follows or given letter references and the references are explained below:

Inductive coil unit
Top plate

S1, S2, S3, … : Coils forming the inductive coil unit

K: Power source

D1, D2, D3, … : Coil arrays arranged from right to left or from the front to back on the top plate of the induction heating cooker

H: Distance between the opposite corners of two coils in quadrilateral form with rounded sides arranged in diagonal position.

X, Y: Horizontal axes that determine the plane of the induction heating cooker top plate.

The inductive coil unit (1) is suitable to be used in induction heating cookers especially in all-surface induction cookers comprising a top plate (2) whereon cooking containers suitable for induction heating are placed, and comprises a plurality of adjacent coils (S1, S2, S3, …) that are produced from conductive wire or wires coated with non-conducting material, that are driven by one or more than one power source with an electric current of the same frequency and that magnetically interact with each other.

The inductive coil unit (1) of the present invention comprises the coils (S1, S2, S3, …), one of which is driven by a current that is electrically in different phase than the adjacent coil (S1, S2, S3, …) (Figure 1)

In the inductive coil unit (1) of the present invention, the coils (S1, S2, S3, …) are driven by alternative current in the same frequency; however, at least one of the two adjacent coils (S1, S2, S3, …) is driven in electrically different phase. When one coil (for example S1) in the inductive coil unit (1) is taken as reference, and if the said reference coil (S1) is driven by a current having zero “0” degree electrical phase angle, the adjacent coil (S2 or S3) is driven by a current having a phase angle that is electrically different than “0” degree, such as 120° or 180°. Thus, two or more adjacent coils (S1, S2, S3, …) with magnetic communication therebetween are enabled to interact with each other such that the magnetic interaction therebetween is increased. Consequently, more power is obtained from the adjacent coils (S1, S2, S3, …) that are driven in different phases than the adjacent coils (S1, S2, S3, …) that are driven in the same phase, and the energy efficiency to be transferred to the cooking container on the induction heating cooker is increased.

In an embodiment of the present invention, the inductive coil unit (1) comprises at least two coils (S1, S2) that are disposed side by side and driven with 180° electrical phase difference. In this embodiment, for example while two coils (S1, S2) each having one unit power provide “2 units” of power in state of the art if the coils (S1, S2) are driven in the same phase, two coils (S1, S2) with the same size and number of windings provide “2.5 units” of power if the coils (S1, S2) are driven by a phase difference of 180°, thus increasing energy efficiency. For example, since, due to 180 ° electrical phase difference, current in opposite directions is applied to the adjacent sides of two identical coils (S1, S2) that are disposed side by side on an induction heating cooker and that are driven in opposite directions (electrical phase difference of 180°), the magnetic interaction between the coils (S1, S2) is increased and more power is transferred with the same unit of current. For example, from two adjacent coils (S1, S2) each having 1000 W power separately, 2500 W power is obtained.

In this embodiment, the two coils (S1, S2) are fed by two separate power sources (K) that apply currents of different phases (Figure 2) or by a single power source (K) that applies current with 180° phase difference such that the electric currents in the coils (S1, S2) flow in opposite directions to one another (Figure 3). In the embodiment where electric current is formed in opposite directions in the two coils (S1, S2) by a single power source (K), the winding inlets and outlets of the first coil (S1) and the second coil (S2) are connected differently to the “+” and “-” terminals of the power source (K). For example, the winding inlet of the first coil (S1) is connected to the “+” terminal of the power source (K) and the winding inlet of the second coil (S2) is connected to the “-“ terminal of the power source (K) (Figure 3).

In an embodiment of the present invention, the inductive coil unit (1) comprises at least four coils (S1, S2, S3, S4) having windings in quadrangular form with rounded corners, that are arranged in the direction of two axes (X, Y) perpendicular to one another that determine a plane, for example the top plate (2) plane such that the centers of the coils (S1, S2, S3, S4) are aligned, each of the coils (S1, S2, S3, S4) being driven with a current in 180° different phase or in opposite direction with respect to the adjacent coil (S1, S2, S3, S4) (Figure 4). On an induction heating cooker top plate (2) the coils ((S1 and S4) and (S2 and S3)) that are diagonal with respect to each other are driven by a current of the same phase; however, the opposite corners of the said diagonal coils ((S1 and S4) and (S2 and S3)) are rounded, the corners through which the current of the same phase passes in the same direction are distanced from each other for a certain distance (H), and the corners that are in diagonal positions are prevented from negatively affecting each other. In this embodiment, the current applied to the windings of the adjacent coils ((S1 and S2), (S2 and S3), (S3 and S4) and (S4 and S1)) is in opposite direction to each other and the magnetic coupling between the adjacent sides thereof provides a strengthening effect for the said coil pairs ((S1 and S2), (S2 and S3), (S3 and S4) and (S4 and S1)) and maximum power is obtained from the inductive coil unit (1) (Figure 4).

In another embodiment of the present invention, the inductive coil unit (1) comprises coils (S1, S2, S3, …) that are arranged in the same alignment on a plane, for example on the top plate (2) of the induction heating cooker so as to cover the whole surface of the top plate (2) on two axes (X, Y) perpendicular to each other, wherein the adjacent coils (S1, S2, S3, …) in right – left (X) and front – rear (Y) directions are driven by 180° phase difference, preferably by a current in opposite direction (Figure 1).

In another embodiment of the present invention, the inductive coil unit (1) comprises coil arrays (D1, D2, D3, …) composed of side by side coils (S1, S2, S3, …) arranged on a plane, for example on the top plate (2) of the induction heating cooker , in right – left directions (X) or in front – rear (Y) directions, and each coil array (D1, D2, D3, …) is supplied by a separate power source (K) (Figure 5, Figure 6).

In an embodiment of the present invention, the inductive coil unit (1) comprises the adjacent coils (S1, S2, S3) on the top plate (2) plane of the induction heating cooker in a three-cornered - trigonal manner such that the centers thereof form a triangle, wherein with respect to the reference first coil (S1) which is assumed to be driven by 0° phase difference (phase 0), the second coil (S2) is driven by 180° electrical phase difference and the third coil (S3) is driven by a constant phase difference that is different from 0° and 180° with respect to the reference first coil (S1) (for example 90° or 120° electrical phase difference). In this embodiment, the coils (S1, S2, S3) have hexagonal or circular windings and preferably each coil (S1, S2, S3) is fed by a separate power source (K) (Figure 7).

In an embodiment of the present invention, the inductive coil unit (1) comprises at least seven coils (S1, S2, S3, S4, S5, S6, S7) with one center coil (S4) and the surrounding coils (S1, S2, S3, S5, S6, S7) that form a hexagonal shape, each coil (S1, S2, S3, S4, S5, S6, S7) being driven by a different phase than the adjacent coil (S1, S2, S3, S4, S5, S6, S7) (Figure 8). In this embodiment, the coils (S1, S2, S3, S4, S5, S6, S7) have hexagonal or circular windings and preferably are fed by more than one power source (K).

In this embodiment, while the center coil (S4) is driven by a phase difference fixed at a value different than 0° and 180° (for example 90° or 120° electrical phase difference), the coils (S1, S2, S3, S5, S6, S7) surrounding the center coil (S4) are driven respectively by currents with phase differences of 0° - 180° - 0° - 180° - 0° - 180° (Figure 8). In the inductive coil unit (1), without changing the arrangement and architecture of the coils (S1, S2, S3, S4, S5, S6, S7) different phase combinations can be used in order to transmit the most power to the cooking container. The center coil (S4) that is driven by 120° phase difference, the coils (S1, S3, S6) driven by 0° phase difference and the coils (S2, S5, S7) driven by 180° phase difference are preferably fed by separate power sources (K).

In another embodiment of the present invention, the inductive coil unit (1) comprises the adjacent coils (S1, S2, S3, …) at least one of which has a different number of windings than the others and the adjacent coils (S1 and S2) and (S2 and S3) are driven by different phases (Figure 9).

In another embodiment of the present invention, the inductive coil unit (1) comprises the coils (S1, S2, S3, …) at least one of which has a different shape of winding than the others and the adjacent coils (S1 and S2) and (S2 and S3) are driven by different phases. In this embodiment, quadrangular, hexagonal or circular winding shapes can be given as examples for different winding shapes (Figure 10).

By means of the present invention, in an inductive coil unit (1), two or more adjacent coils (S1, S2, S3, …) are enabled to positively affect each other, and more power is transmitted to the cooking container on the induction heating cooker without changing the number of coils (S1, S2, S3, …) and/or the winding numbers of the coils (S1, S2, S3, …).

Claims

An inductive coil unit (1) that is suitable to be used in all-surface induction cookers comprising a top plate (2) whereon cooking containers suitable for induction heating are placed, comprising a plurality of adjacent coils (S1, S2, S3, …) that are produced from conductive wire or wires coated with non-conducting material, that are driven with an electric current of the same frequency and that magnetically interact with each other, characterized by the coils (S1, S2, S3, …) at least one of which is driven by a current that is in electrically different phase than the adjacent coil (S1, S2, S3, …).
An inductive coil unit (1) as in Claim 1, characterized by at least two coils (S1, S2) that are fed by two separate power sources (K) that apply currents with 180° phase difference.
An inductive coil unit (1) as in Claim 1, characterized by at least two coils (S1, S2) that are fed by a single power source (K) that applies currents with 180° phase difference.
An inductive coil unit (1) as in Claim 1, characterized by at least four coils (S1, S2, S3, S4) having windings in quadrangular form with rounded corners, that are arranged in the direction of two axes (X, Y) perpendicular to one another that determine a plane such that the centers of the coils (S1, S2, S3, S4) are aligned, each of the coils (S1, S2, S3, S4) being driven with a current in 180° different phase with respect to the adjacent coil (S1, S2, S3, S4).
An inductive coil unit (1) as in Claim 1, characterized by the coils (S1, S2, S3, …) that are arranged in the same alignment on the top plate (2) plane of the induction heating cooker so as to cover the whole surface of the top plate (2) on two axes (X, Y) perpendicular to each other, wherein the adjacent coils (S1, S2, S3, …) in right – left (X) and front – rear (Y) directions are driven by 180° phase difference.
An inductive coil unit (1) as in Claim 5, characterized by coil arrays (D1, D2, D3, …) composed of the adjacent coils (S1, S2, S3, …) on the plane of the top plate (2) of the induction heating cooker in right – left directions (X) or in front – rear (Y) directions, each coil array (D1, D2, D3, …) being fed by a separate power source (K).
An inductive coil unit (1) as in Claim 1, characterized by the adjacent coils (S1, S2, S3) on the top plate (2) plane of the induction heating cooker in a three-cornered - trigonal manner such that the centers thereof form a triangle, wherein with respect to the reference first coil (S1) which is assumed to be driven by 0° phase difference, the second coil (S2) is driven by 180° electrical phase difference and the third coil (S3) is driven by a constant phase difference that is different from 0° and 180° with respect to the reference first coil (S1).
An inductive coil unit (1) as in Claim 7, characterized by the coils (S1, S2, S3) that have circular windings and that are fed by separate power sources (K).
An inductive coil unit (1) as in Claim 7, characterized by the coils (S1, S2, S3) that have hexagonal windings and that are fed by separate power sources (K).
An inductive coil unit (1) as in Claim 1, characterized by at least seven coils (S1, S2, S3, S4, S5, S6, S7) that have hexagonal or circular windings, with one center coil (S4) and the surrounding coils (S1, S2, S3, S5, S6, S7) that form a hexagonal shape, each coil (S1, S2, S3, S4, S5, S6, S7) being driven by a different phase than the adjacent coil (S1, S2, S3, S4, S5, S6, S7).
An inductive coil unit (1) as in Claim 10, characterized by the coils (S1, S2, S3, S5, S6, S7) arranged around the center coil (S4) which are driven respectively by currents with phase difference of 0° - 180° - 0° - 180° - 0° - 180° and the center coil (S4) that is driven by a phase difference fixed at a value different than 0° and 180°.
An inductive coil unit (1) as in Claim 11, characterized by the center coil (S4) that is driven by a phase difference fixed at a value different than 0° and 180° and the coils (S1, S3, S6) that are driven by a current with a 0° phase difference and the coils (S2, S5, S7) that are driven by a current with a 180° phase difference, each one of the coils (S1, S2, S3, S4, S5, S6, S7) being driven by a separate power source (K).
An inductive coil unit (1) as in Claim 1, characterized by the adjacent coils (S1, S2, S3, …) of which at least one (S1, S2, S3, …) has a different winding shape and/or a different number of windings from the other coils (S1, S2, S3, …).