Method of operating an inductive cooking system

Abstract

A method for operating an inductive cooking system (1, 2), wherein the inductive cooking system (1, 2) comprises an inductive cooktop (1) and a cooking vessel (2) with a temperature sensor (23) on or in the cooking vessel wall (21), wherein the cooking vessel (2) is arranged on a cooking zone (12) of the inductive cooktop (1), comprising the steps: • if a first detected sensor value of the temperature sensor (23) reaches the boiling temperature of a liquid, preferably water, operation (300) of the cooking zone (12) with a decay power (P1) for a first period, • at the end of the first period, detection (400) of a second sensor value of the temperature sensor (23), • operation (500) of the cooking zone (12) with a ramp power (P2) to reach the boiling temperature for a second period, • at the end of the second period, renewed operation (600) of the cooking zone (12) with the Decay power (P1) for the first predetermined period and at the end of the first period,Acquiring (700) a third sensor reading from the temperature sensor (23), • Determining (800) the difference between the second and third sensor readings, • Comparing (900) the determined difference with a difference value, and, • if the determined difference is not less than the difference value, repeating the steps from operating (500) the cooktop (12) with the boost power (P2).

Description

[0001] The invention relates to a method for operating an inductive cooking system, such an inductive cooking system and an inductive hob therefor.

[0002] The trend in home cooking is increasingly toward making cooking easier, more convenient, and / or safer for the user with regard to achieving the desired cooking result. This can be supported by providing the user with fully automated programs or assistance functions that relieve the user of part or even all of the cooking process. A cooking process can also be supported, for example, by the hob and / or a mobile device, where the cooking process can be tracked, presented to the user, and the next steps in the recipe sequence can be displayed or appropriate instructions can be given to the user.

[0003] Furthermore, cooktops are increasingly being visually blended into the kitchen. This also includes making the cooktop controls increasingly unobtrusive or even disappearing completely. This may lead to the cooktop controls being relocated to the cookware. Therefore, it may be necessary, or at least desirable, for information to be exchanged between the cookware and the cooktop. This may include the transmission of instructions as well as measurements.

[0004] This also includes providing sensors on and / or in the cooking utensil, for example, to detect the temperature of the food being cooked and transmit this sensor information, particularly wirelessly, to external devices such as the cooktop and / or its control unit. This can, for example, enable a temperature-controlled or temperature-regulated cooking process.

[0005] WO 2022 / 063506 A1 relates to a cooking utensil comprising a utensil body and at least one handle arranged on the utensil body, wherein the utensil body defines a cooking utensil receiving space that is upwardly open in the use position of the cooking utensil for receiving a cooking utensil. The cooking utensil has a plurality of sensors in the form of temperature sensors distributed over a height of the inner wall of an outer shell. The sensors are connected to a control system of the cooking utensil in a signal-transmitting manner, and the sensors are arranged on the outer shell so as to be elastically movable relative to the outer shell.

[0006] DE 10 2020 101 983 A1 describes a cookware comprising at least one base and at least one wall, wherein at least one receiving volume is defined by the base and the wall. At least two temperature sensors are assigned to the wall, wherein a first temperature sensor is provided at a first height and a second temperature sensor is provided at a second height at a predetermined distance from the first temperature sensor.

[0007] US 2012 / 168425 A1 discloses a method for operating an inductive cooking system according to the preamble of claim 1.

[0008] The problem with the use of cooking utensils and / or cookware with at least one temperature sensor on and / or in the wall is that when such utensils are used on hobs with several coils which are intended to heat the utensils simultaneously, in particular together, the temperature sensor can be positioned or oriented in relation to the coils of the hob, in which the electromagnetic field causes additional heating of the side wall where the temperature sensor is located.

[0009] The temperature sensor therefore does not detect the actual temperature of the side wall and / or the wall of the cooking and / or cooking utensil, which results from the inductive heating of the base of the cooking and / or cooking utensil and is actually intended to be detected by the temperature sensor. Instead, it detects the local inductive heating of the wall in the vicinity of the temperature sensor, which happens to be caused by an unfortunate positioning or orientation of the temperature sensor relative to the cooktop coils. This temperature is usually significantly higher than the temperature actually intended to be detected, so that temperature-controlled or temperature-regulated operation of the cooking and / or cooking utensil now leads to incorrect results. In particular, heating of the food may be reduced or stopped too early because the temperature is incorrectly assumed to be higher than the actual temperature.

[0010] When using cooking utensils with sensors, such as temperature sensors, it is important to remember that inaccuracies in the measurement value can occur. This can be caused by inaccuracies in the calibration of the sensors or the electronics, as well as by sensor error tolerances.

[0011] Furthermore, when measuring the boiling point of water using sensors, it should be noted that the boiling point of water depends on the ambient atmospheric pressure and thus decreases when water is boiled at a relatively high altitude above sea level (sea level or normal altitude). The boiling point under normal pressure, i.e., the standard boiling point, is 100°C. The absolute temperature of the boiling point of water decreases with increasing altitude above sea level, for example, to 93°C at an altitude of 2,000 m above sea level.

[0012] If a cooking system is to perform an automatic process to boil or boil water, the cooking system must take the changed boiling point into account. If the boiling temperature is specified as 100°C at sea level, but the cooking system is used at a significantly higher altitude, causing the boiling temperature to drop significantly below 100°C, the automatic process can never reach 100°C because the boiled water evaporates, and thus the temperature sensor cannot detect a water temperature of 100°C.

[0013] This leads to a waste of energy, as the automatic process will never stop trying to reach the 100°C water temperature. Furthermore, the boiling temperature is never recognized as reached by the cooking system, which could automatically trigger further steps, such as maintaining the boiling temperature at a lower power level. Otherwise, if a boiling temperature significantly below 100°C is used and the cooking system is used at sea level, a water temperature below the actual boiling temperature will be incorrectly recognized as the boiling temperature reached.

[0014] This could be avoided by the user adjusting the boiling temperature to the actual or current installation altitude of the cooking system, but this would be laborious for the user and could also be forgotten.

[0015] EP 2 772 692 A2 describes a hob device, in particular an induction hob device, with at least one contact module intended to be arranged on at least one cooking utensil and having at least one sensor unit intended to determine at least one cooking parameter. The hob device has at least one control unit intended to monitor the cooking parameter at least during a cooling process.

[0016] The invention therefore addresses the problem of providing a method for operating an inductive cooking system and / or an inductive cooking system of the type described above, such that the boiling point of liquids, and in particular of water, can be detected by sensors better, and in particular more reliably, than previously known. In particular, a cooking process should be able to automatically reach the boiling point better, and in particular more reliably, than previously known. This should be achievable, in particular, regardless of the installation altitude above sea level. At the very least, an alternative to the known possibilities should be created.

[0017] According to the invention, this problem is solved by a method for operating an inductive cooking system, by an inductive cooking system, and by an inductive cooktop having the features of the independent patent claims. Advantageous embodiments and further developments of the invention are set forth in the following subclaims.

[0018] Thus, the invention relates to a method for operating an inductive cooking system, wherein the inductive cooking system comprises an inductive cooking surface, preferably an inductive surface cooking surface, and at least one cooking utensil with at least one temperature sensor on or in the cooking utensil wall, wherein the cooking utensil is arranged on a cooking area, preferably on a cooking zone, of the inductive cooking surface, the method comprising at least the steps: if a first detected sensor value of the temperature sensor substantially reaches the boiling temperature of a liquid, preferably water, operating the cooking area at a predetermined decay power for a first predetermined period of time, at the end of the first predetermined period of time, detecting a second sensor value of the temperature sensor, operating the cooking area at a predetermined increase power to reach the boiling temperature for a second predetermined period of time, at the end of the second predetermined period of time, operating the cooking area again at the predetermined decay power for the first predetermined period of time and at the end of the first predetermined period of time, detecting a third sensor value of the temperature sensor, determining the difference between the second detected sensor value and the third detected sensor value, comparing the determined difference with a predetermined difference value, and,If the determined difference is not less than the predetermined difference value, repeat the steps starting from the operation of the cooking area with the predetermined increase power.

[0019] The present invention is based on the finding that a liquid such as water or an aqueous cooking liquid such as soups, sauces, vegetable cooking water, and the like cannot be heated above its boiling point, since at the boiling point or boiling temperature, the liquid transforms into a gaseous state. Thus, the boiling temperature physically represents the maximum temperature the liquid can reach.

[0020] This is exploited according to the invention in that, when the boiling temperature is supposedly reached according to a first detected sensor value of the temperature sensor of the cooking utensil, a check is carried out to determine whether the boiling temperature detected by the sensor corresponds to the actual boiling temperature or not, i.e. whether the first detected sensor value is not perhaps above the actual boiling temperature and thus the actual temperature of the liquid is below its boiling temperature. This can be the case if the cooking utensil wall in the area of ​​the temperature sensor is additionally heated, for example by electromagnetic fields of the induction coils, in particular by stray fields in inductive surface cooking surfaces. This can also be the case due to inaccuracies in the calibration of the temperature sensor or due to error tolerances of the temperature sensor.

[0021] Therefore, if the boiling temperature is reached according to the first detected sensor value, the cooking zone's power is reduced to a decay power level, which can be a specific lower power level than the initial power level or even zero, i.e., including switching off the cooking zone's power. The reduction in the cooking zone's power is preferably sufficiently small so that, at a minimum possible fill level in the cooking utensil, no further heating of the liquid or, alternatively, the empty cooking utensil cannot occur, but the heat losses from the cooking utensil are compensated by radiation to the environment. In any case, further heating of the liquid can be avoided. This occurs for a predetermined and, in particular, short first period of a "heating pause" or "pause phase."

[0022] At the end of the first period, the liquid temperature is again recorded by a sensor as a second temperature value. The liquid is then heated again for a second period, known as the "heating phase," followed by another "heating pause" or "pause phase," at the end of which a third temperature value is recorded. The temperature difference is then calculated from the two most recently recorded temperature values, i.e., the second and third temperature values ​​at the end of the "heating pause."

[0023] If this temperature difference is less than the predetermined difference value of, for example, 0.5°C, it can be concluded that the liquid could no longer absorb the power of the "heating phase" and thus the boiling temperature has actually been reached.

[0024] However, if the temperature difference is greater than the predetermined difference value, the liquid was able to at least partially absorb the power of the "heating phase" and has thus been further heated. Therefore, the first recorded sensor value is incorrect, and further heating of the liquid was or is necessary to actually reach the boiling point.

[0025] For this purpose, a new "heating phase" can be performed, followed by a "heating pause," at the end of which a fourth sensor value is recorded and compared with the third sensor value as the previous sensor value, as described above. This can be repeated until the predetermined difference value is reached or maintained, thus ensuring that the last sensor-detected temperature corresponds to the boiling point of the liquid and the boiling point of the liquid is actually reached.

[0026] According to one aspect of the invention, the method comprises at least the preceding steps: Operating the cooking area at a predetermined initial power to substantially reach the boiling temperature of the liquid, detecting a first sensor value of the temperature sensor, comparing the first detected sensor value with the boiling temperature and, if the first detected sensor value does not reach the boiling temperature, continuing to operate the cooking area at the predetermined initial power.

[0027] This allows the liquid to be heated up until the boiling point according to the first recorded sensor value is reached, which can then be checked and / or verified as described above. The current or most recently recorded sensor value from these process steps can be used as the first recorded sensor value when the boiling point is presumably reached.

[0028] According to a further aspect of the invention, the method comprises at least the further step: if the determined difference is less than the predetermined difference value, operating the cooking area with a predetermined holding power and / or a subsequent control to maintain the boiling temperature.

[0029] This allows the actual boiling temperature to be maintained automatically.

[0030] According to a further aspect of the invention, the predetermined decay power is at most half, preferably at most one-quarter, of the predetermined initial power. This prevents the cooking utensil from cooling down during pauses. For example, a pre-boiling process can be supported because cooling down, as occurs with a power of 0W, is avoided, thus shortening the pre-boiling process.

[0031] According to a further aspect of the invention, the predetermined decay power is predetermined such that, at a minimum possible fill level in the cooking utensil or when the cooking utensil is empty, no further heating of the liquid occurs, but the heat losses from the cooking utensil are compensated by radiation to the environment. By compensating for the heat loss to the environment, the cooking utensil does not cool down unnecessarily, so that the temperature of the food inside the cooking utensil can be reliably measured without additional heating influence.

[0032] According to a further aspect of the invention, the predetermined boost power is at least twice, preferably at least three times, the predetermined decay power. This advantageously ensures that the boost power can heat the cooking utensil, since the boost power is greater than the decay power and is preferably also less than the maximum power close to the boiling point.

[0033] According to a further aspect of the invention, the predetermined boost power is lower than the predetermined initial power, preferably at most 90% of the predetermined initial power. This advantageously allows energy savings without adversely affecting the cooking process being performed, since a lower energy input is required near the boiling point than at the beginning of the proposed process.

[0034] According to a further aspect of the invention, the predetermined holding power is greater than the predetermined decay power, at least one and a half times the predetermined decay power. The holding power is preferably implemented by a power control to maintain this holding power. The greater holding power compared to the decay power prevents the food from cooling down and allows the boiling state to be maintained.

[0035] According to a further aspect of the invention, the predetermined holding power is less than the predetermined boost power, preferably at least half, particularly preferably at least one-third, of the predetermined boost power. After the food has been thoroughly heated, less power is required than during the heating phase, so that energy can be saved after the thoroughly heated phase in this embodiment.

[0036] According to a further aspect of the invention, the boiling point is the boiling point of water at an altitude above sea level, preferably approximately 93°C. This allows an approximation of the actual boiling point, so to speak, "from below," so that the method according to the invention can also be used to determine the actual boiling point if the inductive cooking system is used above sea level.

[0037] According to a further aspect of the invention, the predetermined difference value is 0.5°C or less. With a difference of 0.5°C or less, it can be assumed with sufficient accuracy that the boiling point has been found. Preferably, a difference of 0°C is not selected in order to compensate for additional disturbances such as fluctuations in the measurement electronics or drift in the temperature sensors.

[0038] According to a further aspect of the invention, the first predetermined period and / or the second predetermined period is shorter than 30 seconds, preferably shorter than 20 seconds, and / or longer than 5 seconds, preferably longer than 10 seconds. This can represent a suitable implementation option for reaching the desired boiling point as quickly as possible. Preferably, the predetermined periods, i.e., the pause, must be long enough for the additional sidewall heating caused by the hotspot to dissipate.

[0039] According to a further aspect of the invention, the temperature sensor is arranged below the level of the liquid in the cooking utensil. This can ensure that the temperature of the liquid can be detected as described above.

[0040] The present invention also relates to an inductive cooking system with an inductive hob, preferably an inductive surface hob, and at least one cooking utensil with at least one temperature sensor on or in the cooking utensil wall, wherein the cooking utensil is arranged on a cooking area, preferably on a cooking zone, of the inductive hob, wherein the inductive cooking system, preferably a control unit of the inductive hob and a control unit of the cooking utensil, is designed and configured: if a first detected sensor value of the temperature sensor reaches the boiling point of a liquid, preferably water, to operate the cooking area at a predetermined decay power for a first predetermined period of time, at the end of the first predetermined period of time, to detect a second sensor value of the temperature sensor, to operate the cooking area at a predetermined increase power to reach the boiling point for a second predetermined period of time, at the end of the second predetermined period of time, to operate the cooking area again at the predetermined decay power for the first predetermined period of time and at the end of the first predetermined period of time, to detect a third sensor value of the temperature sensor, to determine the difference between the second detected sensor value and the third detected sensor value, to compare the determined difference with a predetermined difference value and,If the determined difference is not less than the predetermined difference value, repeat the steps starting from the operation of the cooking area with the predetermined increase power.

[0041] In this way, an inductive cooking system can be provided to enable the implementation of the method according to the invention as described above with its properties and advantages.

[0042] The present invention further relates to an inductive hob, preferably an inductive surface hob, with at least one cooking point, preferably a cooking zone, and with a control unit which is designed: if a first detected sensor value of the temperature sensor reaches the boiling point of a liquid, preferably water, to operate the cooking area at a predetermined decay power for a first predetermined period of time, at the end of the first predetermined period of time, to obtain a second sensor value of the temperature sensor, to operate the cooking area at a predetermined increase power to reach the boiling point for a second predetermined period of time, at the end of the second predetermined period of time, to operate the cooking area again at the predetermined decay power for the first predetermined period of time and at the end of the first predetermined period of time, to obtain a third sensor value of the temperature sensor, to determine the difference between the second detected sensor value and the third detected sensor value, to compare the determined difference with a predetermined difference value and,If the determined difference is not less than the predetermined difference value, repeat the steps starting from the operation of the cooking area with the predetermined increase power.

[0043] In this way, an inductive cooking surface can be provided to enable the implementation of the method according to the invention as described above or the implementation of an inductive cooking system as described above with its properties and advantages.

[0044] In other words, the invention is based on the finding that in surface cooking surfaces or bridge zones, if the cooking utensil is positioned unfavourably, additional side wall heating can occur due to the magnetic fields of connected, uncovered coils.

[0045] If sensors for measuring the food temperature are mounted on the side wall, they can be disrupted by the additional self-heating of the wall. The sensors then measure a supposedly excessive food temperature, the use of which has a negative impact on potential control and regulation software.

[0046] If a software is supposed to detect the fault of the sensor-detected excessive temperature and initiate appropriate countermeasures, its complexity increases and performance decreases.

[0047] For cookware with temperature sensors on the side of the cookware, this means that if the cookware is placed or pushed onto a position on the surface cooktop, the effect described above can occur. If this error is not addressed, this can lead to incorrect boiling point detection by the software, as temperatures are measured that are too high compared to the contents. If the boiling point detection is triggered incorrectly, the user will be falsely informed that the food is boiling, even though it has not yet reached boiling temperature.

[0048] In addition, inaccuracies in the calibration of the electronics and / or error tolerances of the sensors can make it difficult to detect the boiling point using absolute temperatures within the planned cooking program.

[0049] Furthermore, it can be advantageous if the planned cooking method can function regardless of the installation altitude of the cooktop used. The absolute boiling point of water decreases with increasing installation altitude above sea level, e.g., to 93°C at 2000 m above sea level. If no external information about the cooktop's location is available, it would be advantageous if, in controlled cooking methods, the changed boiling point could be detected from measured temperature signals, allowing the method to react accordingly.

[0050] According to the invention, the negative influence of side wall heating on the control and regulation process of the cooking utensil can therefore be reduced by the inventive method of repeated boiling point detection in the cooking process of the cooking utensil.

[0051] In addition, the method of repeated boiling point determination can enable the boiling point to be determined independently of the installation altitude of the hob above sea level and independently of systematic errors in the sensors and / or measuring electronics.

[0052] As previously mentioned, the invention is based on the finding that if, in the case of surface cooktops or cooktops with multiple induction coils under a cooking zone, a cooking utensil is placed on the coils in such a way that one or more activated coils are only partially covered, this can lead to inhomogeneous heating of the side wall of the cooking utensil. The magnetic field of the only partially covered coils can cause eddy currents on the side wall of the cooking utensil, which can lead to localized heating, known as a hotspot.

[0053] The areas of the cookware wall not affected by hotspots are approximately in thermal equilibrium with the food inside the cookware or the air above it. Thermal sensors mounted on, on, or in the side of the cookware can be used to control the cooking process, e.g., by adjusting the cooktop's power based on temperature signals.

[0054] However, at the hotspot positions, the sensors measure an excessively high temperature signal, which can negatively impact the cooking process because temperatures there may be overestimated. This can, for example, lead to premature triggering and a premature transition to the continued cooking phase when determining the boiling point.

[0055] In addition, the actual boiling point may vary depending on the installation altitude (93°C to 100°C) and / or the absolute temperature measurement of the sensor system may be inaccurate, so that the detection of the boiling point via absolute temperatures can be very difficult.

[0056] However, the cooking methods of the cookware should be able to reliably detect the boiling point of the medium used, even with these uncertainties.

[0057] According to the invention, this is achieved by repeated boiling point detection.

[0058] Repeated boiling point detection can solve or at least reduce these problems by monitoring the signal from a temperature sensor and cyclically performing at least two, and if necessary, several, heating and pause phases with reduced heating power under identical conditions. Identical conditions here means that the pause duration is identical and the heating power per cycle, i.e., heating and pause phases, is constant.

[0059] At the end of each cycle, the temperatures are compared. If two consecutive temperature measurements show no further increase, or if the temperature difference is less than 0.5°C, it can be assumed that the actual boiling point of the medium being heated has been reached.

[0060] The sensor used can advantageously be located below the fill level of the medium in the pot.

[0061] The heating power supplied during the pause phase can preferably be adjusted so that at a minimum possible filling level no further heating of a reference medium such as water can occur, but the heat losses of the pot are compensated by radiation to the environment.

[0062] This can have the advantage that the residual power available in the pause phases can shorten the time until the boiling point is reached compared to a process with pause phases without power supply.

[0063] A further advantage of this method may be that it can be very robust against changes in external conditions that negatively affect the temperature measurement. For example, the boiling point can still be reliably found and / or reached if the pot is rotated or moved from a disturbed position on the induction hob to an undisturbed position, or if cold water is added to the cookware and / or pot. These effects can lead to a change in the measured temperature level at the end of the pause phase and can thus be compensated for by the method according to the invention.

[0064] Only when no further temperature increase occurs in two or more consecutive cycles is the boiling point found or reached, because the medium to be heated can then no longer absorb any more energy. Furthermore, a temperature drop would also be detected. Such a temperature drop would indicate an incorrect measurement or a shift in the cooking vessel, which would in turn trigger a heating and pause cycle.

[0065] An embodiment of the invention is shown purely schematically in the drawings and is described in more detail below. It shows Figure 1 shows a schematic representation of an inductive cooking system for carrying out a method according to the invention with an inductive cooking surface according to the invention with a cooking utensil, viewed diagonally from above; Figure 2 shows the representation of the Figure 1with cooking utensils rotated by 90°; Figure 3 shows a flow diagram of a method according to the invention; and Figure 4 shows a curve of temperature and power over time during the implementation of a method according to the invention.

[0066] The above figures are viewed in Cartesian coordinates. There is a longitudinal direction X, which can also be referred to as depth X or length X. Perpendicular to the longitudinal direction X extends a transverse direction Y, which can also be referred to as width Y. Perpendicular to both the longitudinal direction X and the transverse direction Y extends a vertical direction Z, which corresponds to the direction of gravity. The longitudinal direction X and the transverse direction Y together form the horizontal X, Y, which can also be referred to as the horizontal plane X, Y.

[0067] Figure 1shows a schematic representation of an inductive cooking system 1, 2 for carrying out a method according to the invention with an inductive hob 1 according to the invention with a cooking utensil 2 from an angle above. Figure 2 shows the representation of the Figure 1 with cooking utensils rotated 90°.

[0068] The cooking utensil 2 represents a pot 2. The cooking utensil 2 has a cooking utensil base 20 and a cylindrical cooking utensil wall 21. Several temperature sensors 23 are arranged on and / or in the cooking utensil wall 21. The temperature sensors 23 are arranged offset from one another in the transverse direction Y or in the circumferential direction of the utensil wall 21, as well as in the vertical direction Z. The temperature sensors 23 are operated or evaluated by a control unit 22 in the form of electronics 22 of the cooking utensil 2.

[0069] The cooking utensil 2 is used on an induction hob 1 in the form of an induction surface hob 1, which has a glass ceramic plate 10 with induction coils 11 arranged underneath in the vertical direction Z. The cooking utensil 2 is placed on the glass ceramic plate 10, and the cooking utensil base 20 is designed to be large in area relative to the induction coils 11, such that the cooking utensil base 20 is inductively heated by at least two induction coils 11. The two induction coils 11, partially covered by the pot 2, together form a cooking zone 12.

[0070] However, the only partial coverage of the induction coils 11 of the cooking zone 12 by the pot 2, i.e., its cooking utensil base 20, results in magnetic field lines B of the induction coils 11 coupling as stray fields directly into the cooking utensil wall 21 and leading there to local heating points A, which can also be referred to as hotspots A. These local heating points A can, if they are sufficiently close to one of the temperature sensors 23, influence its temperature detection and thus lead to a detected temperature that is greater than the actual cooking utensil temperature.

[0071] According to the invention, a control unit (not shown) of the inductive surface cooking field 1 therefore carries out a method according to the invention in accordance with the flow chart of Figure 3as follows for at least one of the temperature sensors 23: First, the cooking area 12 is operated 000 with a predetermined initial power P0 to reach the boiling point of the liquid in the form of water, which is absorbed by the cooking utensil 2. The cooking utensil 2 and / or its control unit 22 detects 100 a first sensor value of the temperature sensor 23, which is then transmitted wirelessly to the inductive surface cooking surface 1 and / or its control unit. The control unit of the inductive surface cooking surface 1 then compares 200 the first detected sensor value with the boiling point. The boiling point, for example, can be set so low at 93°C that even a boiling point at an altitude of approximately 2,000 m above sea level can be detected or verified using the method according to the invention.In any case, if the first detected sensor value does not reach the boiling temperature, the operation 000 of the cooking zone 12 is continued with the predetermined initial power P0.

[0072] This continues or is checked by sensors until the boiling temperature is supposedly reached. Thus, if the first detected sensor value of the temperature sensor 23 reaches the boiling temperature, the cooking area 12 is operated 300 at a predetermined decay power P1 for a first predetermined period of time. At the end of the first predetermined period of time, a second sensor value of the temperature sensor 23 is detected 400. The cooking area 12 is then operated 500 at a predetermined increase power P2 to reach the boiling temperature for a second predetermined period of time. At the end of the second predetermined period of time, the cooking area 12 is operated 600 again at the predetermined decay power P1 for the first predetermined period of time. At the end of the first predetermined period of time, a third sensor value of the temperature sensor 23 is then detected 700.

[0073] The difference between the second detected sensor value and the third detected sensor value is now determined 800. The determined difference is compared 900 with a predetermined difference value. If the determined difference is not less than the predetermined difference value, it can be concluded that the water in the cooking utensil 2 has still absorbed power and could therefore be heated further. Accordingly, the boiling temperature cannot yet be reached and the first detected sensor value must have been incorrect. Therefore, the steps starting with the operation 500 of the cooking area 12 with the predetermined increased power P2 are repeated until the difference value is maintained, since then the water in the cooking utensil 2 could no longer absorb power and thus could not be heated further.

[0074] Thus, the boiling temperature must now actually be reached. If the determined difference is less than the predetermined difference value, the cooking zone 12 is operated 950 at a predetermined holding power P3 to maintain the boiling temperature. List of reference symbols (part of the description)

[0075] ALocal heating point; hotspot BMagnetic field lines P0Initial power to reach the boiling temperature P1Collapse power P2Increase power to reach the boiling temperature P3Holding power to maintain the boiling temperature XLongitudinal direction; depth; length YTransverse direction; width ZVertical direction X, YHorizontal; horizontal plane 1 induction hob; induction surface hob 10 glass ceramic plate 11 induction coils 12 cooking area; cooking zone 2Cooking utensils; pot 20Cooking utensil base 21Cooking utensil walls 22Control unit; electronics 23Temperature sensors 000Operating the cooking area 12 with a predetermined initial power P0 100Detecting a first sensor value 200Comparing the first detected sensor value with the boiling temperature 300Operating the cooking area 12 with a predetermined decay power P1 400Detecting a second sensor value 500Operating the cooking area 12 with a predetermined increase power P2 600Reoperating the cooking area 12 with the predetermined decay power P1 700Detecting a third sensor value of the temperature sensor 23 800Determining the difference between the second detected sensor value and the third detected sensor value 900Comparing the determined difference with a predetermined difference value 950Operating the cooking area 12 with a predetermined holding power P3

Claims

1. Method for operating an inductive cooking system (1, 2), the inductive cooking system (1, 2) comprising an inductive hob (1), preferably an inductive surface hob (1), and at least one cooking utensil (2) having at least one temperature sensor (23) on or in the cooking utensil wall (21), the cooking utensil (2) being arranged on a hot plate (12), preferably on a cooking zone (12), of the inductive hob (1), characterised by the method comprising at least the following steps: • operating (300) the hot plate (12) at a predetermined decay power (P1) for a first predetermined period of time if a first captured sensor value of the temperature sensor (23) reaches the boiling temperature of a liquid, preferably water, • capturing (400) a second sensor value of the temperature sensor (23) at the end of the first predetermined period of time, • operating (500) the hot plate (12) at a predetermined increase power (P2) to reach the boiling temperature for a second predetermined period of time, • operating (600) the hot plate (12) at the predetermined decay power (P1) for the first predetermined period of time again at the end of the second predetermined period of time, and capturing (700) a third sensor value of the temperature sensor (23) at the end of the first predetermined period of time, • determining (800) the difference between the second captured sensor value and the third captured sensor value, • comparing (900) the determined difference with a predetermined threshold value, and, • repeating the steps from the operation (500) of the hot plate (12) at the predetermined increase power (P2) if the determined difference is not less than the predetermined difference value.

2. Method according to claim 1, comprising at least the following preceding steps: • operating (000) the hot plate (12) at a predetermined initial power (P0) to reach the boiling temperature of the liquid, • capturing (100) a first sensor value of the temperature sensor (23), • comparing (200) the first captured sensor value with the boiling temperature and, • continuing the operation (000) of the hot plate (12) at the predetermined initial power (P0) if the first captured sensor value does not reach the boiling temperature.

3. Method according to either claim 1 or 2, comprising at least the following further step: • operating (950) the hot plate (12) at a predetermined holding power (P3), and / or subsequent controlling to maintain the boiling temperature, if the determined difference is less than the predetermined difference value.

4. Method according to any of the preceding claims, wherein the predetermined decay power (P1) is at most half, preferably at most a quarter, of the predetermined initial power (P0).

5. Method according to any of the preceding claims, wherein the predetermined decay power (P1) is predetermined in such a way that, at a minimum possible fill level of the cooking utensil (2), no further heating of the liquid occurs, but the heat losses of the cooking utensil (2) by radiation to the environment are equalised.

6. Method according to any of the preceding claims, wherein the predetermined increase power (P2) is at least twice, preferably at least three times, the predetermined decay power (P1).

7. Method according to any of the preceding claims, wherein the predetermined increase power (P2) is less than the predetermined initial power (P0), preferably at most 90% of the predetermined initial power (P0).

8. Method according to any of the preceding claims, wherein the predetermined holding power (P3) is greater than the predetermined decay power (P1), at least one and a half times the predetermined decay power (P1)9. Method according to any of the preceding claims, wherein the predetermined holding power (P3) is smaller than the predetermined increase power (P2), preferably at least half, particularly preferably at least one third, of the predetermined increase power (P2).

10. Method according to any of the preceding claims, wherein the boiling point is the boiling point of water at an altitude above sea level, preferably approximately 93°C.

11. Method according to any of the preceding claims, wherein the predetermined difference value is 0.5°C or less.

12. Method according to any of the preceding claims, wherein the first predetermined period of time and / or the second predetermined period of time is shorter than 30 seconds, preferably shorter than 20 seconds, and / or longer than 5 seconds, preferably longer than 10 seconds.

13. Method according to any of the preceding claims, wherein the temperature sensor (23) is arranged below the fill level of the liquid in the cooking utensil (2).

14. Inductive cooking system (1, 2) comprising an inductive hob (1), preferably an inductive surface hob (1), and at least one cooking utensil (2) having at least one temperature sensor (23) on or in the cooking utensil wall (21), the cooking utensil (2) being arranged on a hot plate (12), preferably on a cooking zone (12), of the inductive hob (1), characterised by the inductive cooking system (1, 2), preferably a control unit of the inductive hob (1) and a control unit of the cooking utensil (2), being designed and configured: • to operate the hot plate (12) at a predetermined decay power (P1) for a first predetermined period of time if a first captured sensor value of the temperature sensor (23) reaches the boiling temperature of a liquid, preferably water, • to capture a second sensor value of the temperature sensor (23) at the end of the first predetermined period of time, • to operate the hot plate (12) at a predetermined increase power (P2) to reach the boiling temperature for a second predetermined period of time, • to operate the hot plate (12) at the predetermined decay power (P1) for the first predetermined period again at the end of the second predetermined period of time, and to capture a third sensor value of the temperature sensor (23) at the end of the first predetermined period of time, • to determine the difference between the second captured sensor value and the third captured sensor value, • to compare the determined difference with a predetermined difference value and • to repeat the steps from the operation of the hot plate (12) at the predetermined increase power (P2) if the determined difference is not less than the predetermined difference value.

15. Inductive hob (1), preferably inductive surface hob (1), comprising at least one hot plate (12), preferably a cooking zone (12), and comprising a control unit which is characterised by: • operating the hot plate (12) at a predetermined decay power (P1) for a first predetermined period of time if a first captured sensor value of the temperature sensor (23) reaches the boiling temperature of a liquid, preferably water, • obtaining a second sensor value of the temperature sensor (23) at the end of the first predetermined period of time, • operating the hot plate (12) at a predetermined increase power (P2) to reach the boiling temperature for a second predetermined period of time, • operating the hot plate (12) at the predetermined decay power (P1) for the first predetermined period again at the end of the second predetermined period, and obtaining a third sensor value of the temperature sensor (23) at the end of the first predetermined period, • determining the difference between the second captured sensor value and the third captured sensor value, • comparing the determined difference with a predetermined difference value and • repeating the steps from the operation of the hot plate (12) at the predetermined increase power (P2) if the determined difference is not less than the predetermined difference value.

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