INDUCTION HOB AND METHOD FOR CONTROLLING AN INDUCTION HOB

Description

SCOPE OF APPLICATION AND STATE OF THE ART

[0001] The invention relates to an induction cooktop.

[0002] With induction cooktops, it is technically possible to detect the presence of a pot above the induction heating coil, or on a cooking zone defined by the induction heating coil, even with just a single coil, provided the pot is suitable for induction heating. However, with modern induction cooktops, such as those conforming to EP 2 670 211 A2, a multitude of distributed induction heating coils makes it possible to cook not only with exactly one pot on exactly one cooking zone with exactly one induction heating coil. This is achieved by using a large number of significantly smaller induction heating coils, of which, for example, five or seven, when sufficiently covered by a pot, effectively form a cooking zone for that pot and heat it.However, since it is desirable to be able to place pots anywhere on such an induction cooktop, it may not be sufficient to simply treat adjacent induction heating coils as a single cooking zone and apply the same power output based solely on the detection of a pot. Therefore, EP 2 670 211 A2 proposes the use of additional pot detection sensors, distributing a large number of these sensors across the induction cooktop.

[0003] From EP 3 026 981 A1, it is known to arrange the sensor coils in such an induction cooktop as to ensure that one or two sensor coils are arranged over each adjacent area formed by the adjacent or mutually facing sides of two neighboring induction heating coils. They are positioned approximately centrally between the induction heating coils and overlap these two adjacent induction heating coils.

[0004] From EP 3 490 339 A1, an induction cooktop with multiple induction heating coils and a large number of pot detection sensors is known. The pot detection sensors are very long and very narrow. They are arranged in the spaces between the induction heating coils. All spaces between adjacent induction heating coils are equipped with pot detection sensors.

[0005] From EP 2 312 908 A1, another cooktop with four heating elements is known. A planar support with a multitude of pot detection sensors arranged in a regular, close pattern extends above the heating elements. As an alternative to a uniform arrangement of the pot detection sensors in a regular pattern, it can be provided that no pot detection sensor is arranged above the center point of each heating element. In this case, several pot detection sensors are also arranged in positions where they do not overlap any heating element, and in some cases are not even in close proximity to one.

[0006] From EP 2 194 754 A1, a cooktop with pot detection sensors is known, wherein the pot detection sensors are also rectangular and elongated. A pair of such pot detection sensors operates together. It is provided that some of these pot detection sensors are arranged above a heating element, and others are arranged outside and beside it. The pot detection sensors arranged beside the heating element are at a considerable distance from it and thus do not overlap or extend over it.

[0007] From DE 10 2006 043 182 A1, an induction cooktop is known with four induction heating elements. Above each induction heating element, two secondary coils are arranged as sensor coils, which are connected antiparallel and can detect a cooking vessel placed above them by means of the magnetic field they generate. In one embodiment, even four sensor coils can be arranged, which makes it particularly easy to detect whether a pot is placed centrally above them and above the induction heating element.

[0008] From EP 3 021 639 A1, a further induction cooktop with induction heating coils is known. It includes a detection device to recognize when a pot is placed over the induction heating coils. This detection device is not described in detail; it is only defined by a description of its function. In particular, it is intended to detect when two pots are placed over one induction heating element.

[0009] From US patent 2015 034 630 A1, another induction cooktop with induction heating coils is known, in which temperature sensors are arranged above some of the induction heating coils in a position that is not precisely identifiable. One temperature sensor is arranged above each of the induction heating coils, with a third temperature sensor located in a space between the induction heating coils. Below this, and thus between the two induction heating coils, at a certain distance, is an inductive pot detection sensor, which can detect a pot placed above it and, if applicable, its temperature. TASK AND SOLUTION

[0010] The invention is based on the objective of creating an induction hob of the aforementioned type with which problems of the prior art can be solved and, in particular, it is possible to detect the position of a pot on the induction hob with not too much effort and to use it for controlling the induction hob or the induction heating coils.

[0011] This problem is solved by an induction cooktop with the features of claim 1. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below. Some of the features are described only for the induction cooktop or only for the method of controlling it. The wording of the claims is incorporated into the description by express reference.

[0012] The induction cooktop is designed to have a cooking surface and several induction heating coils arranged beneath it. It also includes several sensor coils located beneath the cooking surface, advantageously positioned above the induction heating coils. Both the induction heating coils and the sensor coils are flat and run in parallel planes. These planes are also parallel to the cooking surface, allowing for a flat design of the entire induction cooktop. Two adjacent induction heating coils form a so-called adjacent zone with their adjacent sides or their sides facing each other. This adjacent zone is advantageously strip-shaped if the induction heating coils are rectangular or polygonal and not circular. In any case, each adjacent zone lies between two adjacent induction heating coils.

[0013] According to the invention, no sensor coil overlaps an adjacent area or, more generally, two induction heating coils. Thus, each sensor coil runs only above a single induction heating coil and therefore maintains a certain distance from any adjacent induction heating coil. This distance to an adjacent induction heating coil can advantageously be more than 0.3 cm, particularly advantageously more than 0.8 cm, or even more than 1.2 cm. This condition applies according to the invention when the two adjacent induction heating coils are operated out of phase with the adjacent area between them, above which a sensor coil runs.

[0014] In the context of this application, "in phase" refers to whether the induction heating coils are operated on the same phase or mains phase, or on the same conductor of a three-wire connection (i.e., a three-phase network). "Out of phase" refers to the operation of the two induction heating coils on two different phases or mains phases. This can refer, in particular, to each induction heating coil being individually connected to such a mains phase or conductor via its own inverter, a common DC bus, a converter, and a mains filter. Induction heating coils operated in phase are connected to the common DC bus via their respective inverters. The common DC bus is, in turn, supplied from such a mains phase via a converter and a mains filter.Induction heating coils operated in opposite phases are connected to different DC busbars, each with its own inverter, which are supplied from different phases of the grid.

[0015] With the aforementioned exception of in-phase operated induction heating coils, over which a sensor coil may be arranged in an overlapping fashion, the aforementioned spacing requirement should therefore prevent interference with the sensor coil. In the case of induction heating coils operated in phase or on the same mains phase, their respective magnetic fields do not cause interference for the sensor coil that could negatively affect its measurement. However, if adjacent induction heating coils are not operated in phase, then, according to the invention, no sensor coil may overlap these two induction heating coils.

[0016] The invention thus enables improved pot detection without requiring, for example, the induction heating coils to interrupt their heating operation during a measurement process at the sensor coils. Even if this interruption lasts only a short time, such as less than 1 second, advantageously less than 0.1 seconds, it disrupts their heating operation and can cause noise as well as unwanted mains feedback or interference within the power electronics of the induction cooktop.

[0017] The induction heating coils can be rectangular or approximately rectangular. They are advantageously slightly elongated, and particularly advantageously 10% to a maximum of 50% longer than they are wide. The approximately rectangular shape results from the fact that the coil windings cannot extend all the way to the corners or should not be bent. The radius at the corners can therefore be between 1 cm and 3 cm, and possibly even 5 cm. Nevertheless, the shape is essentially rectangular or is considered to be so. A fundamentally similar rectangular induction heating coil is known from DE 20 2006 016 551 U1.

[0018] In one embodiment of the invention, the induction heating coils can be designed differently, particularly in different sizes. In another advantageous embodiment, all induction heating coils are the same size and / or even identical. This simplifies and reduces manufacturing costs. Furthermore, a flat induction cooktop can then easily be equipped with a number of induction heating coils. It is particularly advantageous for all induction heating coils of an induction cooktop to have the same winding direction. This also means that, in principle, their mounting orientation is always the same. The certain distance between adjacent induction heating coils, as well as the advantageous use of conventional ferrite cores on the induction heating coils, prevents negative effects of mutual interference.

[0019] Particularly advantageous are at least two induction heating coils arranged one behind the other and at least three induction heating coils arranged side by side. This means that at least six induction heating coils can be provided on the induction cooktop, preferably eight to twelve.

[0020] Furthermore, according to the invention, two adjacent induction heating coils form a neighboring region, wherein these two induction heating coils lie within or define this neighboring region with their adjacent sides. Advantageously, two adjacent induction heating coils have a certain distance from each other, i.e., a distance between their outermost windings or between the windings defining the sides. This distance can be between 1 cm and 3 cm.

[0021] The distance between two adjacent induction heating coils, or rather their outermost windings, can also be less than 1 cm, for example, even less than 5 mm or less than 3 mm. This is a very small distance that simultaneously allows for very good and as complete a coverage as possible of the induction cooktop surface with induction heating coils. A sensor coil positioned above one of the induction heating coils is advantageously located entirely above this coil. It should be offset, particularly with its own outermost winding, at least 0.2 cm inwards from the outermost winding or edge of the induction heating coil to ensure sufficient clearance from the adjacent induction heating coil. It is advantageous to offset it at least 0.4 cm or at least 1 cm inwards to ensure it is not obstructed.

[0022] In an advantageous embodiment of the invention, all sensor coils of the induction cooktop are arranged in a regular pattern, advantageously in one direction, and particularly advantageously regularly in two or all directions. This applies especially when the induction heating coils are also identically designed and arranged identically or in a regular pattern, preferably also with respect to one winding direction. It can be provided that two, three, or four sensor coils are always arranged above one induction heating coil. Thus, a sufficiently high resolution for detecting a pot placed on the cooktop, as well as its size and position, is possible.

[0023] In one embodiment of the invention, the center point of each induction heating coil can be unobstructed and not covered by a sensor coil. In a further embodiment, the invention can provide that a certain area around this center point is also unobstructed by a sensor coil. This unobstructed area can be circular and have a diameter of 0.5 cm to 2 cm or even up to 4 cm. A sensor coil does not necessarily have to be positioned above the center point of an induction heating coil because a pot placed in this area can always be reliably detected by the induction heating coil itself as an inductive sensor.

[0024] In an advantageous embodiment, all sensor coils can be of the same size, and in particular, they can be identical. Their winding direction can also always be the same. This allows for easy installation of an induction cooktop using a single sensor coil design.

[0025] In an advantageous embodiment of the invention, all sensor coils can be arranged within the surfaces of the induction heating coils or do not project laterally beyond the surfaces of the induction heating coils. By arranging the sensor coils exclusively within the surfaces of the induction heating coils in this way, the adverse effects of two adjacent induction heating coils operating out of phase can be prevented.

[0026] For an advantageous design of the induction cooktop, it can be provided that several sensor coils are arranged on a common carrier. For example, all sensor coils for each induction heating coil or for each pair of adjacent induction heating coils can be arranged on such a common carrier. This facilitates quick and precise installation of the induction cooktop. Such a carrier can be, for example, a flat mounting plate or carrier film. The carrier can be placed on the induction heating coils, or it can be attached using an electrical plug connector.

[0027] In an advantageous embodiment of the invention, the sensor coils are provided to have a round shape, in particular a circular shape. This is primarily because, unlike in induction heating coils, their geometric shape is not of crucial importance, and this round shape facilitates simple manufacturing and covers a certain area. A sensor coil can, for example, have 10 to 80 turns, preferably between 30 and 60. Its diameter can be between 2 cm and 5 cm, preferably between 3 cm and 4 cm.

[0028] In a further embodiment of the invention, a sensor coil or all sensor coils can have or carry a temperature sensor, for example, in their central region or at a central point, particularly at the top. The sensor coil and temperature sensor can form a single unit, advantageously also with a single electrical connection, so that they can be easily installed and connected. The temperature sensor is particularly advantageously a temperature-dependent resistor, for example, an NTC or a PT1000. The temperature sensor can be used together with the sensor coil to reliably detect when a pot is placed on top of it, for example, if no temperature increase occurs despite the induction heating coil being in operation. Additionally or alternatively, it can be used for normal temperature sensor functions, such as a hot indicator.

[0029] In an advantageous embodiment of the invention, the induction heating coils can have a single layer of windings, or their windings can run in a single layer and thus in a single plane. Preferably, all induction heating coils run in the same plane. This is advantageously parallel to the cooktop surface and also parallel to a plane in which the sensor coils run. Similarly, but fundamentally independently of this, in an alternative, the sensor coils can also be wound in a single layer, or their windings can run in a single layer or in a single and advantageously common plane. Preferably, in another alternative, the sensor coils are designed in two layers, i.e., they have two layers of windings on top of each other. In this way, a sufficient number of windings can be achieved with a not too large diameter, so that they may, if necessary,They can be more easily arranged at a sufficient distance from adjacent induction heating coils. Within the scope of the invention, this can still be considered a plane of the sensor coil. Preferably, all sensor coils lie in the same plane. Preferably, the plane of the sensor coils does not lie in the plane of the induction heating coils, and is particularly preferably located above them.

[0030] The sensor coils can also be advantageously designed to be identical to each other, thus reducing the number of components. Alternatively, in a sensor coil, all turns have approximately the same diameter, with deviations ranging from one to five times the wire thickness. In this case, the turns essentially form a bundle with the smallest possible vertical extent and diameter of the sensor coil. The geometric extent of the bundle would be a disadvantage, but the higher inductance with fewer turns would be advantageous.

[0031] In the aforementioned method for controlling an induction cooktop, the sensor coils are designed to be continuously active, detecting whether a pot is placed on the cooktop above them. This continuous operation means that the sensor coils are not operated every second or continuously, but rather intermittently, for example, every few seconds, such as every 0.5 to 30 seconds. However, the operation of an induction heating coil to heat a pot should not mean that the sensor coils cease to function. For the sake of simplicity, and advantageously in intermittent operation, it may be possible to have all sensor coils continuously active, detecting, or attempting to detect, whether a pot is placed above them every 0.5 to 30 seconds.If a sensor coil's function is impaired by an induction heating coil operating directly below or adjacent to it, this is not a problem, as it can then be assumed that a pot is in place or sufficiently covered by the induction heating coil. Otherwise, the induction heating coil would cease heating due to its own operating conditions, particularly if the pot is not sufficiently in place or if there is insufficient coverage.

[0032] Advantageously, the resonant frequency of the sensor coils and their evaluation circuitry is significantly higher than the operating frequency of the induction coils, preferably 5 to 30 times higher. This allows them to operate more efficiently and avoids interference. It is particularly advantageous that an induction coil is only activated for heating a pot if at least one of the sensor coils is covered by a pot. This ensures the presence of a pot. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Exemplary embodiments of the invention are shown schematically in the drawings and are explained in more detail below. The drawings show: Fig. 1 a top view of an induction hob according to the invention in a simple embodiment, Fig. 2 an arrangement of induction heating coils similar to that shown in Fig. 1 with distance between adjacent induction heating coils, Fig. 3 a top view of a detailed induction hob according to the invention with a further variant of an arrangement of sensor coils and three pots placed on top of each other, Fig. 4 an enlargement of a section of the induction hob made of Fig. 3 with sensor coils that slightly overlap an adjacent area between two adjacent induction heating coils, and Fig. 5 a further enlargement of a section of the induction hob from Fig. 3with an alternative arrangement of sensor coils that strongly or even completely overlap a neighboring area. Detailed description of the exemplary implementations

[0034] In the Fig. 1 An induction cooktop 11 according to the invention is shown in a top view in a very simple embodiment. The induction cooktop 11 has a cooktop plate 12, the large rear portion of which forms a heating zone 13. Eight rectangular induction heating coils 15a to 15h, which are identical in design, are arranged in this heating zone. For the sake of simplicity, they are shown directly adjacent to one another. However, this is not mandatory; they can be spaced 0.5 cm to 2 cm apart. This spacing can be advantageous for their outermost coils, or alternatively for their outer edges, for example, of a support. This will be explained in more detail below.

[0035] A front area of ​​the induction cooktop 11 forms a control area 20. An elongated, wide control unit 21, shown with a dashed line, can be arranged here. For specific designs, reference is made to the state of the art and, in particular, to the Fig. 3 referred.

[0036] Above the induction heating coils 15a to 15h, round sensor coils 25 are arranged. These sensor coils 25 are arranged in a regular pattern across the entire induction cooktop 11, with three such sensor coils 25 positioned above each individual induction heating coil 15. The sensor coils 25 are each completely within the area of ​​the respective induction heating coil 15 and are located at a distance from its edge, which may be, for example, 2 cm to 3 cm. Even if the outermost windings of the induction heating coils 15 (not shown here) do not extend to the dividing lines, and thus the adjacent areas 23 formed between neighboring induction heating coils 15 are somewhat wider, for example, also 1 cm to 2 cm, these sensor coils 15 are still located within the area formed by the outermost windings of each induction heating coil 15.All induction heating coils 15 and sensor coils 25 are identically designed here.

[0037] Within the upper row of induction heating coils 15a to 15d, two sensor coils 25 are arranged one above the other on the left, at a distance of approximately 2 cm to 3 cm from the left edge of the induction heating coils 15. At the same distance from the right edge of each induction heating coil 15, and thus halfway up or in the middle of the two left sensor coils 25, a single sensor coil 25 is arranged.

[0038] The spacing of the sensor coils 25 within the horizontal rows is exactly the same. Since the arrangement of induction heating coils 15e to 15h in the lower row is essentially a mirror image, with a single central sensor coil 25 at the left edge and two stacked sensor coils 25 at the right edge, the overall pattern of the sensor coils 25 is regular. Therefore, the vertical spacing of the sensor coils 25 is also exactly the same. A total of 24 sensor coils 25 are provided. For their control and evaluation, reference is made to the aforementioned prior art.

[0039] In the illustration of an induction hob 111 in Fig. 2In the diagram, of which only the induction heating coils 115a to 115h are shown, the adjacent areas 123 between neighboring induction heating coils are somewhat wider. Thus, the outer edges of the individual induction heating coils 115 could represent their geometric or structural outer edge, possibly with a support. Alternatively, they could also be the outermost turns of the windings of the induction heating coils 115.

[0040] Here too, it can be seen that all sensor coils 125 are arranged or run completely within the area of ​​the respective induction heating coil 115. In the upper horizontal row of induction heating coils 115a to 115d, there are four sensor coils 125 above each induction heating coil 115. These are arranged according to exactly the same pattern, but shifted so far into the corners of the respective induction heating coil 115 that there is no uniform distribution or equal spacing within the rows thus formed.

[0041] In the lower row of induction heating coils 115e to 115h, as an alternative configuration, only two sensor coils 125 are arranged. An entire induction cooktop 111 should have either the rear arrangement or the front arrangement of sensor coils 125 above all induction heating coils 115.

[0042] The two sensor coils 125 in the lower row of induction heating coils 115e to 115h are arranged such that one is positioned near the upper edge of the induction heating coil 115 and is located approximately in the center of this short outer edge of the induction heating coil. The second sensor coil 125 is positioned near the right outer edge and is located approximately in the middle of this side of the induction heating coil 115 with respect to its length. Thus, the lower left area above each induction heating coil 115e to 115h remains largely without a corresponding sensor coil 125. However, the placement of a pot in this area can also be detected by the induction heating coil 115 itself detecting a pot above it. The pot's size and position can also be determined in conjunction with the right sensor coil of the induction heating coil 115 to its left. Therefore, under certain circumstances, only two sensor coils per induction heating coil 115 may be sufficient.Within this lower row of induction heating coils 115e to 115h, the arrangement of the sensor coils 125 is again uniform.

[0043] In the Fig. 3 The figure shows in more detail how a cooktop 211 with cooktop plate 212 in the heating area 213 can be configured. The control area 220 with control device 221 located in front of it is configured as known from EP 3026981 A1. Eight induction heating coils 215a to 215h are provided. These are approximately rectangular with rounded corners. Each induction heating coil 215 has a plurality of turns 216, of which the outermost turn 217 is relevant. Each of the induction heating coils 215 is arranged on a support 218, which is basically rectangular and is, so to speak, truncated at the corners, resulting in an almost octagonal shape. The outer edge of the support 218 projects slightly beyond the outermost turn 217, for example by about 1 cm.

[0044] Rod-shaped, flat spacers 219 are provided on top of the induction heating coils 215. They can be made of plastic, preferably silicone, and may, for example, be glued in place. They serve to hold attached functional units, such as carriers for sensor coils 225 (not shown), above them at a certain distance. This is also known from the prior art.

[0045] Between the induction heating coils 215, adjacent areas 223 are formed, their width being approximately 1 cm to 2 cm with respect to the distance from the respective adjacent outer edges of the supports 218. This means that adjacent outermost windings 217 can have a maximum distance of 4 cm to 5 cm from each other, advantageously 1 cm to 3 cm. These distances can, of course, also be smaller for a denser arrangement of the induction heating coils 215, or alternatively for a somewhat larger design. A minimum distance of a few millimeters between the outer edges of the supports 218 is considered advantageous so that they do not touch and can be easily mounted in the cooktop 211. In an advantageous embodiment of the invention, the outer edges of the supports 218 can have a distance from each other of 1.2 cm in the lateral direction and 1.6 cm in the front / back direction.The distances between the adjacent outermost turns 217 can then each be about 0.4 cm larger.

[0046] Adjacent areas 223 are also provided between induction heating coils 215, which run adjacent to each other with their short sides. The dimensions of these adjacent areas 223 and the corresponding distances are advantageously located within the aforementioned range.

[0047] According to the distribution of sensor coils by Fig. 1The sensor coils 225 are arranged distributed above the induction heating coils 215, here on supports that are not shown for clarity. These supports are advantageously planar and made of an electrically insulating material that does not interfere with the magnetic fields of the induction heating coils 215 and is not affected by them. Such a material can be, for example, a film such as Kapton or the like, or alternatively, thin carrier discs made of micanite or the like. Three sensor coils 225 are provided above each induction heating coil 215. The considerations regarding their distribution have been explained above and also apply here. The sensor coils 225 above the induction heating coils 215a to 215d are arranged in horizontal rows, and within these rows they are equidistant. Thus, there is a regular arrangement for the rear four induction heating coils 215a to 215d.

[0048] Above each of the four front induction heating coils 215e to 215h, three sensor coils 225 are provided. However, these are distributed differently. While two sensor coils 225 are arranged side by side in the same manner towards the shorter rear side, forming a single row, only a single sensor coil 225 is provided in the front section. In the case of induction heating coil 215e, this sensor coil 225 is shifted to the right of the center, and in the case of induction heating coil 215h, it is shifted to the left of the center. In the intermediate induction heating coils 215f and 215g, the sensor coils 225 are positioned exactly in the center relative to the short front side of the induction heating coils 215. This specific arrangement is designed to anticipate how an operator is likely to place a pot on the heating element and thus facilitates a suitable arrangement of the sensor coils 225.In the case of the four front-mounted induction heating coils 215e to 215h, the sensor coils 225 each have the aforementioned inward distance to the outermost winding 217. Thus, there is a large distance of at least 3 cm or 5 cm, or even more, to the outermost winding 217 of the adjacent induction heating coil 215. However, it can also be less, as will be explained below.

[0049] Based on the position of three different pots 214a, 214b, and 214c, including their respective coverage of the sensor coils 225 (shown with dashed lines) or the uncovered sensor coils 225, the cooktop 211, or a control unit (not shown) in the operating device 221, can determine the size and position of each pot 214. This is clearly possible for pot 214c. The covered induction heating coil 215d registers at least one pot placed above it, which corresponds to a signal from the fully covered sensor coil 225 in the lower left. The adjacent sensor coils 225 are all uncovered, as are the induction heating coils 215c and 215h. Thus, the size and position of pot 214c can be determined very accurately.

[0050] For pot 214b, the control unit can detect that the upper left sensor coil 225 above the induction heating coil 215g is fully covered, while the sensor coil 225 to its right and the one below it are only partially covered. The induction heating coil 215f can also detect some coverage, which, however, also originates from pot 214a. The distinction between pots 214a and 214b cannot be made directly by the induction heating coil 215f itself. Its upper right sensor coil 225 is not covered, nor is the lower sensor coil 225. Therefore, pot 214b cannot be much larger than it actually is, nor much smaller, because otherwise the sensor coil 225 in the upper left or lower position above the induction heating coil 215g would be covered differently or not at all.

[0051] For pot 214a, a similar approach is used. The partial coverage of the sensor coils 225 at the top left of the induction heating coil 215a and at the top left and center right of the induction heating coil 215b allows for the approximate determination of the edge. The partial coverage of the sensor coil 225 at the top left and the full coverage of the sensor coil 225 at the top right above the induction heating coil 215e already allow for a sufficiently accurate determination of the position and size of pot 214a. By adding the information from the two upper sensor coils 225 above the induction heating coil 215f—namely, full coverage at the top left and no coverage at the top right—the exact location of pot 214a can be determined. Precisely because a sensor coil 225 is exposed between pots 214a and 214b, located to the right above the induction heating coil 215f, it can be determined that the total absolute coverage of the induction heating coil 215f must come from two different pots.

[0052] Due to the distance between the sensor coils 225 and the outermost winding 217 of the respective adjacent induction heating coil, a very high level of detection reliability can be achieved, regardless of whether the adjacent induction heating coils 215 are operated in the same or opposite phase. In particular, measurement using the sensor coils 225 can be carried out continuously, even during heating operation of the respective induction heating coil 215, without the need for planned interruptions.

[0053] In the Fig. 4 Under high magnification, an induction cooktop is similar to... Fig. 3The two induction heating coils 215e and 215f shown in the lower left illustrate how the distances of the sensor coils 225 above the left induction heating coil 215e, which they partially or predominantly overlap, to the outermost winding 217f of the adjacent induction heating coil 215f on the right can be configured in various ways. In the example of the uppermost sensor coil 225, it can be seen that its outermost winding, which corresponds to the depicted circular boundary, extends to approximately the middle of the adjacent area 223ef. Thus, its distance to the outermost winding 217f can be 1 cm, 2 cm, or up to 3 cm and is always sufficiently large. The induction heating coils 215e and 215f could therefore also be operated out of phase without any negative effects on the sensor coil 225.

[0054] In the example of the middle sensor coil 225, it can be seen that it extends to just before the left edge of the support 218f. Its distance to the outermost winding 217f is therefore between 0.5 cm and 1 cm and is considered too short for the two induction heating coils 215e and 215f to be operated in opposite phases or on different mains phases. If a measurement is to be taken with the sensor coil 225 and both the induction heating coil 215e and the induction heating coil 215f are operating in heating mode, the induction heating coil 215f must be briefly switched off, as explained previously, for a measurement to be taken on the sensor coil 225. While this is theoretically possible, it is considered a significant disadvantage.

[0055] In the example of the lowest sensor coil 225, it can be seen that it only slightly overlaps the left induction heating coil 215e, for example, the outermost two or three turns 216e, i.e., by less than 1 cm or only 0.5 cm. It extends to just before the outermost turn 217f of the right induction heating coil 215f, so that while it does not yet overlap it, it comes very close. The distance can therefore be 0.5 cm or less. In the case of out-of-phase operation or operation on different mains phases of the two induction heating coils 215e and 215f, it is therefore always necessary to interrupt the operation of at least one of the induction heating coils 215e and 215f in order to take a measurement at the sensor coil 225.

[0056] In the Fig. 5Another installation situation is shown in which the two sensor coils 225 partially cover the right induction heating coil 215h, specifically its two or three outermost turns 216h. They overlap the adjacent area 223 and extend to an outer edge of the support 218g of the left induction heating coil 215g. Thus, their distance to an outermost turn 217g is approximately 0.5 cm, which is considered too small to heat with both induction heating coils 215g and 215h when measurements are to be taken with these sensor coils 225, at least when the induction heating coils are operated out of phase or on different mains phases.

Claims

1. Induction cooktop (11, 111, 211) with - a cooktop plate (12, 212), - a plurality of induction heating coils (15, 115, 215) arranged beneath the cooktop plate (12, 212), and - a plurality of sensor coils (25, 125, 225) arranged beneath the cooktop plate (12, 212), wherein - the induction heating coils (15, 115, 215) and the sensor coils (25, 125, 225) are flat and run in planes that are parallel to each other and parallel to the cooktop plate (12, 212), - two adjacent induction heating coils (15, 115, 215) form a neighboring area (23, 123, 223) with their adjacent sides, characterized in that - no sensor coil (25, 125, 225) overlaps in a neighboring area (23, 123, 223) over two induction heating coils (15, 115, 215) that are operated out of phase or that are operated on different mains phases of a mains connection and are each supplied with power from these different mains phases.

2. Induction cooktop according to claim 1, characterized in that the distance between two adjacent induction heating coils (15, 115, 215) or their outermost windings (217) is less than 10 mm, wherein a sensor coil (25, 125, 215) is arranged completely above this induction heating coil (15, 115, 215), wherein the sensor coil (25, 125, 225) is offset inwardly by at least 2 mm from an outermost winding (217) or an outer edge of the induction heating coil (15, 115, 215).

3. Induction cooktop according to one of the preceding claims, characterized in that all sensor coils (25, 125, 225) of the induction cooktop (11, 111, 211) are arranged in a regular pattern, wherein two, three, or four sensor coils (25, 125, 225) are always arranged above an induction heating coil (15, 115, 215).

4. Induction cooktop according to one of the preceding claims, characterized in that each center point of all induction heating coils (15, 115, 215) is free without being covered by a sensor coil (25, 125, 225).

5. Induction cooktop according to one of the preceding claims, characterized in that all induction heating coils (15, 115, 215) and / or sensor coils (25, 125, 225) are of equal size.

6. Induction cooktop according to one of the preceding claims, characterized in that each of the sensor coils (25, 125, 225) has 10 to 60 turns.

7. Induction cooktop according to one of the preceding claims, characterized in that all sensor coils (25, 125, 225) are arranged within the areas of the induction heating coils (15, 115, 215).

8. Induction cooktop according to one of the preceding claims, characterized in that a plurality of sensor coils (25, 125, 225) are arranged on a common carrier.

9. Induction cooktop according to one of the preceding claims, characterized in that the induction heating coils (15, 115, 215) have a single layer of windings (216) and the windings (216) run in a single plane.

10. Induction cooktop according to one of the preceding claims, characterized in that the sensor coils (25, 125, 225) have two layers of windings (216) on top of each other, wherein the sensor coils (25, 125, 225) run above the plane of the induction heating coils (15, 115, 215).