METHOD FOR OPERATING AN INDUCTION HOB AND INDUCTION HOB

Description

SCOPE OF APPLICATION AND STATE OF THE ART

[0001] The invention relates to a method for operating an induction cooktop, in particular with specially designed cooking vessels. The invention also relates to an induction cooktop designed for this purpose.

[0002] From DE 10 2004 016 631 A1, an arrangement is known with which the placement of a cooking vessel and its position on a heating device or a heating zone of a cooktop can be detected. Here, several capacitive sensors are provided on the exterior of a heating device.

[0003] From DE 10 2018 221 521 A1, an induction cooktop with induction heating coils is known, featuring a code for transmitting energy in a pattern from the induction heating coils to a cooking vessel that may be placed above them. The cooking vessel has a transmitting device that can detect this energy and, if necessary, sends a specific signal or a sequence of signals, corresponding to the received code, to a control unit of the induction cooktop. This allows a specific induction heating coil to be assigned to a cooking vessel placed above it.

[0004] From EP 2 981 154 A1, another induction cooktop with induction heating coils is known, in which three additional detection coils are provided per induction heating coil. These detection coils generate their own field, which is dampened or modified by a cooking vessel placed above it. From the overall change in the fields of all detection coils, it can be deduced whether and, if so, where a cooking vessel is placed.

[0005] From EP 3 749 056 A1, a cooking system is known with an induction cooktop having four induction heating coils, some of which are used for inductive heating and some for transmitting assignment signals. A cooking vessel placed above the cooktop has a receiver to detect which induction heating coil an assignment signal detected by the receiver should be assigned to. This allows the system to determine which induction heating coil the cooking vessel is positioned over. This specific cooking vessel can then be heated as desired.

[0006] Further induction cooktops are known from EP 3 614 796 A2 and US 2017 / 079093 A1, which allow for the unambiguous identification of placed cookware with regard to its position and individual identifier. In these cookware systems, each cookware unit is equipped with electronics including a transmitter and sensors. TASK AND SOLUTION

[0007] The invention is based on the objective of creating a method mentioned above and an induction cooktop designed for its implementation, with which problems of the prior art can be eliminated and in particular it is possible to reliably detect both the placement of a cooking vessel on or in a heating area and the identity of the cooking vessel and, if necessary, to indicate this to an operator.

[0008] This problem is solved by a method with the features of claim 1 and by an induction cooktop with the features of claim 15. 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 and explained only for the method or only for the induction cooktop. However, they should be applicable to both the method and the induction cooktop independently of each other.

[0009] The method for operating an induction cooktop with multiple induction heating coils provides that each induction heating coil has a heating zone. This zone is essentially formed by the area above it, corresponding to the size of the induction heating coil. A cooking vessel can be arranged on the induction cooktop such that it covers at least one heating zone, advantageously only a single heating zone of an induction heating coil. Each induction heating coil is configured to transfer energy for heating a cooking vessel within its heating zone, and is controlled by a converter in a known manner. Each cooking vessel has a transmitting device with a transmitting antenna for sending a signal that depends on the energy received or the type of energy transmitted by an induction heating coil whose heating zone at least partially covers the cooking vessel. Advantageously, this cooking vessel largely or completely covers the heating zone.

[0010] A receiving device is provided for receiving signals from a transmitter on a cooking vessel, or from all transmitters on cooking vessels, on the induction cooktop. This receiving device can be integrated into the induction cooktop, or alternatively or additionally, it can be located on an external control unit or a mobile device.

[0011] A control unit is provided that receives signals from the receiving device and contains or receives information for sending or transmitting energy from the induction heating coils. This control unit can be located on the induction cooktop, similar to the receiving device, or alternatively or additionally on an external control unit or a mobile device. Preferably, the receiving device and the control unit are arranged together or in the same device.

[0012] The method comprises the following steps: At least one cooking vessel is positioned over a heating zone of an induction heating coil, advantageously exactly one cooking vessel for exactly one detection process. This can be done with the induction cooktop switched off or switched on, as well as with an already operating or heating induction cooktop. A plurality of the induction heating coils, in particular all induction heating coils, are controlled to send or transmit energy in a pattern, whereby the duration and / or amplitude are varied as encoding. The encoding consists of varying the amplitude of the sent or transmitted energy within the encoding over time, in particular varying between zero and a coding maximum value, and / or varying the duration of the energy transmission, and / or varying the time between two energy transmissions, and / or varying the number of energy transmissions.These methods can be used individually or in combination, depending on the number of required codings or induction heating coils to be tested. Energy is sent or transmitted as a code at a frequency of at least 50 kHz, preferably at least 75 kHz to 150 kHz. A code comprises at least one sequence of at least two energy pulses, advantageously exactly three or exactly four pulses, thus forming a pulse train, such that a pulse train consists of at least two pulses. Advantageously, a code comprises at least two pulse trains or sequences of pulses, advantageously exactly three or exactly four pulse trains. Such an energy pulse represents a rapid rise and fall of energy within a short time or for a pulse duration.The advantage of using pulse sequences with at least two pulses each is that the energy drawn from the intermediate circuit of the induction heating coil control can be more easily controlled. Furthermore, noise generation at the induction cooktop can be reduced. Information or coding for a specific induction heating coil can be encoded using various parameters such as pulse width, pulse duration, frequency, number of pulses, etc., in order to shorten the time required to uniquely identify the specific induction heating coil over which the cooking vessel is located. Thus, each pulse sequence alone may be sufficient to identify the induction heating coil. Preferably, the duration of a single pulse or the pulse duration within a pulse sequence can be varied, for example, when starting up a PWM control for the induction heating coil. This can further reduce noise generation.

[0013] If a cooking vessel covers a heating area of ​​an induction heating coil that has transmitted energy with a specific or individual code, the cooking vessel's transmitting device sends a signal or a sequence of signals to the receiving device. These signals are uniquely dependent on this received code and / or can be precisely assigned to this received code. The control unit receives the signals from the receiving device and compares them with information about the energy transmitted by the induction heating coils as codes known to the control unit. In this way, it can determine which code of transmitted energy from a specific induction heating coil corresponds to a received signal or sequence of signals, provided the signal was received at the same time or shortly thereafter.Based on this, the control unit can assign this signal, or this sequence of signals from the cooking vessel, to the heating area or to the induction heating coil associated with that heating area, since it is clear that the cooking vessel could only have received the signal-determining coding from the induction heating coil located below it. Thus, the control unit can determine that this cooking vessel covers the heating area of ​​this induction heating coil. Alternatively, according to the invention, the determination of the transmitting induction heating coil or the determination of the cooking vessel's assignment to the induction heating coil can also take place within the cooking vessel itself, for example, in an integrated circuit or a microcontroller within the cooking vessel. This information is then advantageously transmitted to the aforementioned control unit.

[0014] Subsequently, for example, a cooking program, such as those already known, can be used to precisely control this induction heating coil for heating this cooking vessel. In an advantageous embodiment, sensors can be arranged on the cooking vessel to monitor the cooking process, and their data can then be precisely assigned.

[0015] In an advantageous embodiment of the invention, a cooking vessel has a receiving coil for storing or converting the alternating magnetic field of an induction heating coil, which is used to transmit energy, into electrical energy. The signal can then be transmitted by means of the transmitting antenna of the transmitting device. Advantageously, the energy required for this can be the previously received or stored energy.

[0016] The cooking vessel can be equipped with an energy storage device connected to the receiving coil, the energy received by the receiving coil being stored in the energy storage device as described above. Then, using or corresponding to the stored energy, a signal or a sequence of signals can be transmitted from the transmitting device. This signal advantageously corresponds to the received encoding or contains it or its identifier.

[0017] The energy received by the receiving coil can be used directly to electrically drive the transmitting antenna for sending a signal or a sequence of signals, which can be an alternative to the aforementioned energy storage. The length and / or strength of the at least one signal, and especially the sequence of multiple signals, can correspond to the variance of duration and / or amplitude of the encoding. In this way, information can be transmitted, for example, the number or identifier of the induction heating coil in whose heating range the cooking vessel is located and whose encoding has therefore been received.

[0018] The system can be designed so that the transmitting antenna sends a signal as soon as energy is transferred to the receiving coil from an induction heating coil whose heating area covers the cooking vessel or where the vessel is positioned. Advantageously, the transmitting device sends a signal as long as energy is transferred from the induction heating coil to the receiving coil as a code. As soon as no more energy is transferred from the induction heating coil to the receiving coil, the transmitting device also ceases to send a signal.

[0019] In a further embodiment, the sending or transmission of energy in induction heating coils, where it is unknown whether their heating area is covered by a cooking vessel, can be repeated frequently and / or regularly to detect cooking vessels positioned within their heating area. This can be done, in particular, with a frequency or repetition rate corresponding to a time interval of less than 1 minute, preferably less than 5 seconds. In this way, the control system is informed very quickly as soon as such a cooking vessel has been placed within the heating area of ​​an induction heating coil.

[0020] The only advantageous way to send or transmit energy from the induction heating coils with coding is if a cooking vessel with a transmitting device for recognizing a code registers with the induction cooktop, or if an operator enters this into a control unit of the induction cooktop.

[0021] It can be advantageous to provide that the transmission of energy from the induction heating coils, with its coding for detecting cooking vessels positioned within the heating zone, also occurs when a change in the coverage of a heating zone by a cooking vessel is detected. This means the case where the cooking vessel has been moved, either far away from or out of the heating zone, or only by a few centimeters. This can then also be detected.

[0022] In a further refinement of the procedure, it can be stipulated that the process is only carried out on a mobile device or an external control unit with control and receiving capabilities if an app is active on it or if the external control unit is activated. The actual cooking program mentioned above, using the special cooking vessel, can then be carried out on this mobile device or external control unit. If these are not active, the procedure does not need to be carried out. It can be stipulated that the detection of the mobile device or external control unit being switched on or paired with the induction cooktop automatically triggers the start of the procedure.

[0023] It can also be intended that the process is only carried out when a special cooking vessel with the aforementioned receiving coil and transmitting device has been detected on the induction cooktop or in a heating zone. Additional so-called pot detection sensors can also be used for this purpose. Preferably, the cooking vessel also has an integrated circuit and at least one sensor as previously described. The integrated circuit can evaluate the sensor and be used to send the information, including the sensor evaluation (advantageously not just the sensor signal directly and alone), to a control unit of the mobile device or external control unit, or to a control unit of the induction cooktop.

[0024] A coding system preferably consists of very short power outputs, referred to here as pulses, which oscillate or are generated at an operating frequency or the resonant frequency of a resonant circuit with the induction heating coil. The pulses form at least two pulse sequences. A pulse has one or more oscillations or lasts for a certain duration and is thus defined by the oscillations. Preferably, the total duration of a pulse is between 0.1 µsec and 50 µsec, particularly between 10 µsec and 20 or 25 µsec, and is therefore significantly shorter and lower in energy than is the case with the energy transfer for actual heating.

[0025] It can be advantageously provided that the interval between two pulses within a code is the duration of one half-cycle of the power supply network or a multiple thereof, preferably an integer multiple thereof. The frequency of the power supply network can be 50 Hz or 60 Hz, so that the interval can then be 10 ms or slightly over 8 ms.

[0026] The transmitting device can be selected from the following groups: Bluetooth, BLE, Zigbee, NFC, WiFi. Other transmitting devices are of course possible, including those using proprietary transmission protocols. Bluetooth and BLE are preferred due to the widespread use of their protocols, with BLE being particularly favored for its very low power consumption.

[0027] As mentioned previously, the receiver and control unit can be located outside the induction cooktop, preferably in an external control unit. This external control unit then has operating elements and at least one display. It can be a mobile device such as a smartphone or tablet computer, or it can be a dedicated external control unit for this induction cooktop. This may allow new functionalities to be integrated into the induction cooktop or made possible that would otherwise only be achievable with a complex replacement or modification, if at all.

[0028] Preferably, a cooking vessel, in addition to the receiving coil and the transmitting device, also includes an integrated circuit, essentially acting as its intelligence. A certain degree of intelligence can also be incorporated into the transmitting device to process the signals to be transmitted. Preferably, at least one sensor, such as a temperature or pressure sensor, is also provided. This allows the cooking program to be controlled and executed in a known manner, because the condition within the cooking vessel itself can be detected and taken into account by the sensor. Additionally, the aforementioned energy storage device can be a battery, accumulator, or capacitor. Alternatively, the cooking vessel can contain no energy storage device other than a capacitor, so that the energy required to operate the integrated circuit and the transmitting device is stored only within it.

[0029] When controlling all induction heating coils to transmit energy for the detection of cooking vessels positioned within the heating area, energy can first be transmitted briefly as a pulse, followed by a pause. Then, a variety of different codings can be generated through a varying number of short sequences of energy transmission and pausing, or by waiting for a specific multiple of a waiting period. This waiting period multiple can be, in particular, between 5% and 20% or 30% of the total coding duration. Each induction heating coil is controlled with a different coding for sending or transmitting energy with that coding, and each induction heating coil is repeatedly controlled with the same coding. This coding can preferably be permanently assigned to that induction heating coil.

[0030] The control unit conveniently stores information about which cookware is positioned within the heating zone of which induction heating coil. This information is retained at least until something changes or until the control unit and / or the induction cooktop are switched off. The control unit recognizes newly placed cookware within the heating zone of an induction heating coil in the same way.

[0031] Preferably, the control system stores which cooking vessel is moved out of a heating area, which the control system recognizes based on changes in the operating parameters of the resonant circuit with the induction heating coil, i.e., at least through the induction heating coil itself, and possibly also through the aforementioned pot detection sensors.

[0032] In this embodiment of the invention, no encoding is sent or transmitted as long as an induction heating coil, after detecting and assigning a cooking vessel to it or to its heating zone, does not register any change or movement of this cooking vessel within its heating zone. This registration is advantageously achieved, as described above, by detecting a change in the operating parameters of the resonant circuit containing the induction heating coil. Preferably, an encoding is only transmitted again at this or all induction heating coils when a change or movement of the cooking vessel within its heating zone is registered, which can preferably be registered by an induction heating coil or by other sensors.

[0033] Preferably, all induction heating coils should begin transmitting a code or sending energy simultaneously. This may allow this process to be better integrated with the normal operation of the induction cooktop.

[0034] Advantageously, each coding begins with a pulse, or rather, a brief energy transfer for synchronization, which is referred to as a synchronization pulse. This serves to synchronize the timing across all cooking vessels and, if necessary, prepare them for subsequent pulses or coding. From this synchronization pulse onward, each induction heating coil can and should have a different coding so that they can be distinguished from one another, allowing the cooking vessels to send different signals according to their respective coding.

[0035] Advantageously, within all codings, at least two further pulses follow the synchronization pulse at a time interval, the number of which preferably corresponds to the number of a single induction heating coil or the numbering of the induction heating coils plus 1. Particularly advantageous is the time interval between two pulses within a coding, which remains constant until the last pulse before the next synchronization pulse.

[0036] Alternatively, a binary number can be transmitted via encoding. Binary differentiation is achieved by sending a pulse or no pulse at specific points within a predetermined time grid, as is common practice in signal processing. Preferably, a pulse is sent, or energy is briefly transmitted, before the binary number is transmitted, for synchronization purposes, specifically as the aforementioned synchronization pulse. This is important to better distinguish the individual pulses.

[0037] Within all codings, the time interval between two successive pulses can preferably be an integer multiple of a time interval. The number of integer multiples of the time interval between two successive pulses corresponds to a number or numbering of the induction heating coils, wherein, in particular, each coding has exactly two pulses or exactly three pulses, each with the specified interval between them.

[0038] In an advantageous embodiment of the invention, it can be provided that all encodings (n+1) have pulses with (two to n) different interval durations. This allows n induction heating coils to be distinguished. The interval durations can then be evaluated with regard to their combination, which enables the precise identification of the induction heating coil that sent this encoding.

[0039] It is advantageous that the transmitting device sends pre-processed information as a signal, in particular either the number of the induction heating coil as its identifier or its position on the induction cooktop as at least two pulse sequences. This information is derived from the encoding received by an induction heating coil. Specifically, the position of the induction heating coil on the cooktop can be transmitted as an x / y coordinate, based on the number of induction heating coils in the X and Y directions, to locate a specific induction heating coil. Evaluation is advantageously performed in the transmitting device or in an integrated circuit of the cooktop, which is particularly advantageously designed within or in conjunction with the transmitting device. In the aforementioned case of a transmitting device using Bluetooth, BLE, or Zigbee, an integrated circuit is required anyway.Alternatively, the evaluation of the coding can take place in the receiving device or in the control unit.

[0040] Preferably, the method is only performed on induction heating coils whose heating area is actually covered by a cooking vessel. Other induction heating coils can forgo this method and simply send or transmit individual pulses, which are necessary and common practice for detecting the presence of cooking vessels anyway, even without a cooking vessel with a receiving coil. The method can also be performed only on those induction heating coils whose heating area is exactly covered by a cooking vessel.

[0041] With so-called surface cooktops, it's possible for a cooking vessel to cover the heating area of ​​several induction coils. This means the vessel receives the pulse patterns or pulse sequences from all the induction coils whose heating areas it covers. The vessel may therefore have to recognize and extract multiple pulse patterns from individual induction coils from a superposition of different pulse patterns, which is possible. After recognizing such a case, the recognizing induction coils can, as a special case, transmit their codes sequentially.

[0042] The cooktop control of a surface cooktop is normally able to determine which induction heating coil is covered by which cookware. Therefore, preferably when a cookware covers several induction heating coils, the method can be carried out on only one induction heating coil at a time, preferably only on the most covered induction heating coil.

[0043] Furthermore, it is possible that an induction heating coil may be covered by several cooking vessels. Preferably, the method is then only carried out on those induction heating coils whose heating area is covered by only one cooking vessel. If several are detected, the problem can arise that it is not possible to assign a code to exactly one single cooking vessel, since two cooking vessels arranged in the heating area receive the same code.

[0044] The division of the application into individual sections and subheadings does not limit the general validity of the statements made under these. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Further advantages and aspects of the invention will become apparent from the claims and from the following description of preferred embodiments of the invention, which are explained below with reference to the figures. These figures show: Fig. 1 a schematic representation of an induction hob according to the invention in an arrangement with a cooking vessel placed on a heating area of ​​an induction heating coil together with an external control device, Fig. 2 a simplified representation of the functionalities of the intelligent cooking vessel, Figs. 3 to 11 different codings. DETAILED DESCRIPTION OF THE EXECUTION EXAMPLES

[0046] In the Fig. 1 An arrangement 11 is shown with an induction cooktop 13 according to the invention. The induction cooktop 13 has a cooktop surface 14, under which two induction heating coils 16a and 16b are arranged. In practice, more induction heating coils 16 are advantageous, for example four or six up to twenty or thirty in the case of the aforementioned surface cooktops.

[0047] Furthermore, the induction cooktop 13 has a cooktop control unit 18, which is connected to functional units of an inverter device 20, a transmitter / receiver 22, and a control module 24 on the underside of the cooktop surface 14. These functional units are each of a conventional design. As explained above, a radio standard for the transmitter / receiver 22 can, in principle, be implemented in a variety of ways. Advantageous options include Bluetooth or BLE, but also ZigBee, WLAN, or similar technologies, as well as proprietary solutions without a universally accepted standard.

[0048] Above the induction heating coils 16a and 16b, a heating zone is formed with an area approximately equal to the area of ​​the induction heating coils 16. A cooking vessel 27 is arranged in the heating zone 17a or placed there on the top of the cooktop plate 14. The cooking vessel 27 has a receiving coil 32 in a recess 30 of its base 29. The receiving coil 32 has few turns and is arranged on the underside of the base 29 in such a way that it is exposed and not shielded from the magnetic field of the induction heating coil 16a by the rest of the base. This is important for the energy transfer described above. The receiving coil 32 is connected to a cooking vessel module 34, which is located in the Fig. 2 shown in enlarged form.

[0049] Right is in Fig. 1 An external control unit 46 is shown, which can be either a dedicated control unit for the induction cooktop 13 or, alternatively, a mobile device such as a tablet computer or a smartphone. The external control unit 46 has a large display, as shown. Furthermore, as is known especially for the aforementioned mobile devices, it has a receiver, a transmitter, and also a processor or integrated circuit. A wireless standard is suitable for the transmitter / receiver 22, preferably Bluetooth or BLE. Little needs to be said about the external control unit 46; for example, a cooking program as described above can be run on it using an app or a special program. The external control unit shown is not strictly necessary.Its function can also be integrated into an operating and control unit located within the cooktop.

[0050] In the Fig. 2 The cooking vessel module 34 is shown enlarged. The cooking vessel module 34 is connected to the receiving coil 32 by means of an electrical connection, such as a cable. Similarly, the cooking vessel 34 is electrically connected to a temperature sensor 36, which is arranged externally and advantageously according to Fig. 1 The temperature sensor is located inside the cooking vessel 27, so that it is surrounded by the water or food being cooked and can determine its temperature. This temperature sensor can also be embedded in the base of the cooking vessel if the base temperature, rather than the temperature of the food being cooked, is to be measured. Alternatively or additionally, other sensors such as pressure sensors, weight sensors, or the like are conceivable instead of the temperature sensor 36.

[0051] Furthermore, the cooking vessel module 34 has an energy storage device 38 that is directly connected to the receiving coil 32. This can be a battery, but a capacitor is advantageous because it does not need to store particularly large amounts of energy, especially when transmitting via Bluetooth or BLE or Zigbee, which should be done as quickly and without loss as possible.

[0052] The cooking vessel module 34 includes an integrated circuit 40 as a type of control unit, which detects the energy received by the receiving coil 32, or the signals or pulses, advantageously with respect to duration and / or distance and / or amplitude, or also the energy accumulated and stored in the energy storage device 38. The integrated circuit 40 controls a transmitting device 42 with a transmitting antenna 44, advantageously constructed using the aforementioned Bluetooth or BLE standard or Zigbee.

[0053] In the Fig. 3 This diagram illustrates a method for differentiating between four induction heating coils, I1 to I4, based on a simultaneous synchronization pulse sent to all coils. This pulse has an amplitude equal to that of a subsequently sent pulse. The amplitude increases incrementally with the number of the heating coil. While the pulses with different amplitudes are sent simultaneously, they can also be sent with a time delay. Therefore, each pulse sequence contains at least two pulses.

[0054] In the Fig. 4 The diagram shows an example of a coding sequence for two induction heating coils over time t, with the first induction heating coil I1 shown above and the second induction heating coil I2 shown below. The pulse sequences themselves are identical, each consisting of three pulses with a specific duration. The second pulse is twice as long as the first, and the third is three times as long as the first. The pause between the individual pulses in each sequence also varies; the second pause between the second and third pulses is twice as long as the first pause between the first and second pulses. This makes the pulse sequences very characteristic and easily identifiable. These pulse sequences are used for the two induction heating coils shown here, but are advantageously used for all induction heating coils of the induction cooktop.These two pulse sequences are thus varied to determine which induction heating coil a cooking vessel is placed over.

[0055] Here, the time between two pulse sequences, including the start-up of the pulse sequence, is measured to reduce noise generated in the induction cooktop. A start-up is defined as the incrementing of a duty cycle in the power generation for the induction heating coil and / or a rapid reduction in frequency. This controls the energy transfer and the frequency spectrum of the pulse(s). (Illustrated in the...) Fig. 4 The duty cycle and frequency both change. The time interval between the two identical pulse sequences in induction heating coil I1 is A1, while in induction heating coil I2 it is A2 and significantly longer. For yet another induction heating coil, the time interval Ax would then be even longer than A2.

[0056] In the Fig. 5 Two pulse sequences are shown for an induction heating coil I1 and an induction heating coil I2. These pulse sequences, shown in detail, can be used accordingly. Fig. 4 Each pulse sequence must be used at least twice. However, this is not mandatory. The second pulse sequence for the induction heating coil I2 corresponds exactly to the one from... Fig. 4 In the first pulse sequence above for the induction heating coil I1, the time interval A1 between the first and second pulses is exactly twice as long as the time interval A2 in the lower pulse sequence. As a further variation, the time interval between the second and third pulses could also be varied additionally or alternatively.

[0057] The different methods for the aforementioned startup can thus be illustrated, each changing only one parameter. In the upper pulse sequence, the duty cycle is incremented after each pulse sequence or period, while the frequency remains constant. In the lower pulse sequence, a fixed duty cycle is used, for example, 50%, with the frequency adjusted after each pulse sequence or period. In this example, the frequency is reduced after a high starting frequency, approaching the resonant frequency.

[0058] At the Fig. 6 As a simpler variation, a pulse sequence of three short pulses is used for the induction heating coil I1 (top), and a pulse sequence of three pulses more than twice as long is used for the induction heating coil I2 (bottom), with shorter time intervals between the individual longer pulses. Overall, however, the lower pulse sequence lasts slightly longer than the upper one. Thus, a different pulse sequence is used for the induction heating coil I1 (top) than for the induction heating coil I2 (bottom), for example, with a duty cycle of 25% for the upper pulse sequence and 50% for the lower pulse sequence, both at the same frequency.

[0059] At the Fig. 7 The pulse duration and the time interval between pulses are varied in each pulse sequence. For example, a frequency of 70 kHz can be used for the induction heating coil I1 (top) and a frequency of 60 kHz for the induction heating coil I2 (bottom), with the same duty cycle being used for both. The two pulse sequences (top and bottom) can be offset in time, as shown here. However, this is not mandatory; they can also be started simultaneously.

[0060] At the Fig. 8 The number of pulses in both pulse sequences is varied. For the upper induction heating coil I1, three short pulses with short intervals between them are used. For the lower induction heating coil I2, four short pulses with short intervals between them are used, where the pulse duration and the intervals between them correspond to the upper pulse sequence. The duty cycle and frequency can advantageously remain the same.

[0061] In the exemplary embodiments of the Fig. 9 bis 11 A variation of the parameters within a pulse sequence encodes the position of the induction heating coil within the aforementioned coordinate system of the induction heating coil within the induction cooktop. The information can be encoded either by the frequency at the same duty cycle, see [reference]. Fig. 9 und 10 , or by means of the duty cycle at the same frequency, see Fig. 11 .

[0062] The X and Y values, used as indices to determine an arrangement within the coordinate system, can therefore be derived from the signal. It should be noted that whole pulses are always output, although the number can be adapted depending on the frequency. Thus, in Fig. 9 the index 1 corresponds to the value Y 3 pulses, and in Fig. 10 It only has 2 pulses. Depending on the duty cycle, the value X or Y can represent multiple bits, depending on the number of frequencies used. The number of transmitted indices, which can be multiple bits, can be changed depending on the data to be transmitted and the duty cycle. For example, in Fig. 9 und 10 Three indices each, in Fig. 11There are only two indices. It should be noted that for the second value, in this example the value Y, a duty cycle of 0% can also be selected, resulting in amplitude shift keying, a type of digital modulation. Here, the amplitude of the carrier is changed to transmit different values.

Claims

1. Method for operating an induction cooktop (13) with multiple induction heating coils (16), wherein: - each induction heating coil (16) has a heating area (17), - a cooking vessel (27) can be arranged to cover at least one heating area (17), - each induction heating coil (16) is designed to transmit energy for heating a cooking vessel (27) and is controlled by a converter for this purpose, - each cooking vessel (27) has a transmitting device (42) with a transmitting antenna (44) for transmitting a signal depending on the energy received from an induction heating coil (16) whose heating area (17) at least partially covers the cooking vessel (27), - a receiving device (22) is provided for receiving signals from a transmitting device (42) of a cooking vessel (27) or from all transmitting devices (42) of cooking vessels (27) on the induction cooktop (13), - a control unit (18) is provided which receives the signals from the receiving device (22) and has or receives information for transmitting or transferring energy from the induction heating coils (16), wherein the method comprises the following steps: - at least one cooking vessel (27) is arranged above a heating area (17) of an induction heating coil (16), - a plurality of the induction heating coils (16) are controlled to transmit energy in a pattern, whereby the duration and / or amplitude are varied as coding, wherein the coding consists in that o the amplitude of the transmitted energy varies over time within the coding, in particular varying between zero and a maximum coding value, and / or o the duration of the energy transmission varies, and / or o the duration between two energy transmissions varies, and / or o the number of energy transmissions varies, - wherein a coding comprises at least one sequence of at least two pulses and forms a pulse sequence, - a cooking vessel (27) covers a heating area (17) of an induction heating coil (16), which has transmitted energy with a specific code, the transmitting device (42) sends a signal or a sequence of several signals to the receiving device (22), which signals clearly depend on this code and / or can be assigned to this exact code, - the control unit receives the signals received by the receiving device (22) and compares them with information about the energy sent or transmitted by the induction heating coils (16) as codes in order to determine which code of transmitted energy from a specific induction heating coil (16) matches a received signal or a sequence of several signals, in order to assign the cooking vessel (27) transmitting this signal or this sequence of several signals to the heating area (17) or to the induction heating coil (16) associated with the heating area (17), characterized in that the transmission or transfer of energy takes place as coding with a frequency of at least 50 kHz.

2. Method according to claim 1, characterized in that a cooking vessel (27) has a receiving coil (32) in order to store an alternating magnetic field of an induction heating coil (16) used to transmit energy as electrical energy in order to transmit the signal by means of the transmitting antenna (44) of the transmitting device (42).

3. Method according to claim 1 or 2, characterized in that an energy storage device (38) is provided in the cooking vessel (27), which is connected to the receiving coil (32), wherein the energy received by the receiving coil (32) is stored in the energy storage device (38) and wherein a signal or a sequence of several signals is transmitted by the transmitting device (42) in accordance with the stored energy.

4. Method according to one of the preceding claims, characterized in that the transmission or transfer of energy in the case of induction heating coils (16) where it is not known whether or not their heating area (17) is covered by a cooking vessel (27), is repeated frequently and / or regularly, in particular with a frequency or time interval of less than 1 minute, in particular less than 5 seconds, in order to detect cooking vessels (27) located in the heating area (17).

5. Method according to one of the preceding claims, characterized in that the transmission or transfer of energy from the induction heating coils (16) for detecting cooking vessels (27) arranged in the heating area (17) also takes place at least in the case where a change in the covering of a heating area (17) by a cooking vessel (27) is detected.

6. Method according to one of the preceding claims, characterized in that the method is only carried out if a cooking vessel (27) with a receiving coil (32) according to claim 2 and with a transmitting device (42) has been detected on the induction cooktop (13), wherein the cooking vessel (27) preferably also has an integrated circuit (40) and at least one sensor (36).

7. Method according to one of the preceding claims, characterized in that a code consists of pulses, at least two of which form the at least one pulse sequence, wherein the pulses are generated at an operating frequency or the resonance frequency of an oscillating circuit with the induction heating coil (16), wherein a pulse has one or more oscillations, preferably with a total duration between 0.1 µsec and 50 µsec, in particular between 10 µsec and 25 µsec.

8. Method according to one of the preceding claims, characterized in that, when all induction heating coils (16) are activated to transfer energy for detecting cooking vessels (27) arranged in the heating area (17), energy is first transferred as a pulse for a short time, then paused, and then, over a varying number of short sequences of energy transfer and pausing, or by waiting for a certain multiple of a waiting time, which is in particular between 5% and 20% of the duration of the coding, a plurality of different codes is generated and each of the induction heating coils (16) is controlled with a different code, but each induction heating coil (16) is repeatedly controlled with the same code, in order to send or transfer energy with this code.

9. Method according to one of the preceding claims, characterized in that the control unit (18) stores which cooking vessel (27) is arranged in the heating area (17) of which induction heating coil (16), whereby the control recognizes cooking vessels (27) arranged in a heating area (17) of an induction heating coil (16) in the same way.

10. Method according to one of the preceding claims, characterized in that no coding is transmitted or transferred as long as an induction heating coil (16) does not register any change or movement of this cooking vessel (27) in its heating area (17) after recognizing and assigning a cooking vessel (27) by changing the operating parameters of the oscillating circuit with the induction heating coil (16), whereby a code is only transmitted again to this or all induction heating coils (16) when a change or movement of the cooking vessel (27) is detected in its heating area (17), preferably by an induction heating coil (16) or by other sensors.

11. Method according to one of the preceding claims, characterized in that all induction heating coils (16) simultaneously begin to transmit a code as a transmission of energy.

12. Method according to one of the preceding claims, characterized in that each code first has a pulse or a short transmission of energy for synchronization, and from this synchronization pulse each induction heating coil (16) has a different code.

13. Method according to claim 12, characterized in that within all codes after the synchronization pulse, at least two further pulses follow at a time interval and the number of subsequent pulses corresponds to a numbering of the induction heating coils (16), whereby preferably within a code the time interval is the same in each case until the last pulse before the next synchronization pulse.

14. Method according to one of the preceding claims, characterized in that the transmitting device (42) transmits processed information, in particular directly a number of the induction heating coil (16) as a designation or the position of the induction heating coil (16) on the induction cooktop (13) as at least two pulse sequences, which are evaluated from the coding received by an induction heating coil (16), the evaluation preferably taking place in the transmitting device (42), in particular the position of the induction heating coil (16) on the induction cooktop (13) being transmitted as x / y coordinates.

15. Induction cooktop (13) designed to carry out the method according to one of the preceding claims, wherein the induction cooktop (13) has several induction heating coils (16), wherein at least one heating area (17) is assigned to each induction heating coil (16).