EP3836752B1

EP3836752B1 - Cookware placement by heating control loop in an induction cooking system

Info

Publication number: EP3836752B1
Application number: EP19215917.6A
Authority: EP
Inventors: Peter Favrholdt
Original assignee: Ztove Aps
Current assignee: Ztove Aps
Priority date: 2019-12-13
Filing date: 2019-12-13
Publication date: 2023-06-07
Anticipated expiration: 2039-12-13
Also published as: EP3836752A1; EP3836752C0

Description

TECHNICAL FIELD

The present invention relates to cooking by an induction cooktop with improved control, temperature regulation, and safety. Specifically, the invention is directed to cookware having an integrated thermal sensor and another sensor or sensors (e.g., accelerometer, microphone, wire, wire loop or any other) and a method for detection and identification of cookware placement on the cooktop surface, heating zones and within the automated cooking temperature control loop.

BACKGROUND ART

Smart cooking employs systems, methods, and devices for cooking automation, digital regulation, and control by smartphones/apps, and cookware with different sensors, safety means, and other advanced features.
One of the known methods is the precise regulation of the cooking temperature. When cooking food, for obtaining a good result, the heat must be adjusted to the required temperature for the desired cooking process. Such an adjustment can be by the automated temperature control loop. The temperature control is achieved by employing a temperature sensor inside the cookware, e. g., in the bottom plain of the pan or pot. The cookware control electronics read an instant temperature value from the sensor and send it to the induction cooktop, or an external smart device and application (e.g., a smartphone) controlling operation of the cooktop. Therefore, the induction cooktop is controlled by an algorithm determining how much power to supply to the heating coil to achieve the desired temperature in the cookware.
For this type of application, it is necessary to have the cookware placed precisely on the induction cooktop heating area/zone or one of several zones. In this application, it is called "cookware placement". Induction cooktops usually have several heating zones and control with manual setting of heating levels in the zones. Using more than one cookware item and several heating zones or even cooktops (e.g., in shared kitchens) simultaneously, the complexity may exceed convenience and reduce the efficiency and safety of smart cooking.
The right placement of the cookware onto the cooktop heating zone and in the temperature control loop can be verified by making heating power test pulses. It means, the cooktop controller provides one or more short power pulses to the induction heating coil and simultaneously, the temperature increase by the thermal sensor is measured in the cookware, as e.g. described in EP3001771A1 . This method can be used, but it is slow and less precise as the temperature changes rather slowly and with delay by several or tens of seconds.
For some reasons, e.g., displacing cookware to another heating zone, or moving to another cooktop, or for placing the cookware precisely onto the heating zone, it is crucial to have an instant identification how the cookware is placed on the heating zone, which heating zone, or which cooktop in the kitchen.
For instant identification of cookware presence, other sensor types and means are known from the prior art. Chinese patent application CN201710159U discloses a detecting device of cookware motion information during cooking, which matches with cookware in use and comprises a sensor system and a processing module. The sensor system acquires the motion information with the cookware and outputs the information to the processing module for processing to obtain motion change information of the cookware. By mounting the sensor system onto the cookware, the adopted detecting device is used as a cookware motion information measuring medium, measures motion types of the cookware, and corresponding motion starting time and stop time of the motion types, then uses the processing module for processing measured information, and accordingly obtains cookware position change information. However, it is not apparent what motions are detected and how the motion information is employed for smart and automated cooking.
Another application and patent US10448776B2 describes a cooking system that includes a kitchen utensil and a cooking hob, wherein the kitchen utensil is provided with one or more sensors arranged on the kitchen utensil. The sensors include acceleration sensors, gyroscopic sensors, and inclination sensors. The cooking appliance is equipped with a control unit configured to receive data from the sensors and to elaborate information on how the kitchen utensil is being used, and to control the cooking appliance accordingly. For example, this application in Figures 11-13 shows accelerometer and gyroscope signals during flipping, stirring, and whisking movements of the cooking utensil. These movement indications may be useful to identify what actions the user/cook is doing with the utensil; however, these movements and indications are not sufficient to detect cookware placement on the heating areas of the cooktop.
One more patent US9354207B2 discloses boil and boil-dry detection methods for cooking appliances using vibration sensors. The method includes the steps: detecting vibrations that correspond to cookware situated on a burner assembly; generating a vibration signal based on the vibrations and performing signal processing on the vibration signal. The method also includes the steps: collecting vibration data related to the vibration signal; detecting boiling and boil-dry conditions for a liquid contained within the cookware based at least in part on an evaluation of the vibration data. The method may also include the steps: indicating the boiling and boil-dry conditions; controlling the burner assembly based at least in part on the boiling and boil-dry conditions. These vibration sensors detect vibrations due to the boiling water, and the method is applicable also on electric and gas cooktops. A similar system, using vibration sensors such as MEMS acceleration sensors installed in the induction hob to detect when boiling is achieved, is described in EP2999301A1 . However, this type and origin of vibrations are not much useful for proper and instant placement of cookware onto the heating areas of the induction cooktop.
The relevant prior art is patent application US20190125120A1 where, according to one example, a system comprises a heat source system and a processor. The heat source system comprises a plurality of heat sources. Each heat source is operable to provide an amount of energy to be used for cooking a food item. The processor is operable to determine that a cooking device system has been positioned on or in a first heat source of the plurality of heat sources, determine an identity of the cooking device system that has been placed on or in the first heat source, and correlate the determined identity of the cooking device system with an identity of the first heat source. This application also mentions motion sensors in cookware and cookware movements employed to control the cooking process. Vibrations of the cookware are also mentioned, however, only in the sense of providing messages/indications by vibration or vibration by stirring. However, this type and origin of vibrations are not much useful to detect placement of cookware on the heating areas of the induction cooktop.
In summary, the reviewed prior art sources do not disclose that the alternating electric and magnetic field induced from heating coils and the respective cookware base vibrations occurring due to induction heating frequencies can be employed for identifying and helping to correct the placement of the cookware on the cooktop surface and heating zones. This invention discloses using this type of vibrations and magnetic and/or electric field strength measurements for cookware placement on the cooktop and heating zones.

SUMMARY OF THE INVENTION

This invention discloses the use of the heating power, the induced alternating electric and/or magnetic field, and respective vibrations generated from the induction cooktop heating zones to the cookware placed onto the surface of the cooktop. The heating power is supplied to induction coils by frequencies of several tens of kilohertz (for example, 25.8 kHz) which induces the alternating magnetic field. Additionally, this high-frequency magnetic field is often amplitude-modulated by the power line-frequency, e.g. 50Hz. Said alternating magnetic field moves the magnetic base of the cookware correspondingly, thus producing physical vibrations. The benefit of these vibrations and magnetic field alternations is that they can be detected by, e.g., a 1-, 2- or 3-axis accelerometer, or microphone and identified by their frequency and state transitions related to the heating power is on or off, and also to the heating power magnitude delivered to the induction coils. Another option is measuring the induced electric and/or magnetic field by an integrated wire loop, an energy harvesting coil, a temperature sensor and/or associated wire or wires, or any other type of sensor.
Besides these vibrations, also cookware thermal sensor indications and changing heating power magnitude are applied to heating zones of the cooktop or several cooktops. Further, more than one accelerometer and/or more than one thermal sensor can be in a single cookware item (e. g. large pot), and analysis of temperature and/or vibration frequency characteristics can be employed to indicate precise and symmetric placement of the cookware item onto the heating zone of the cooktop.
The invention discloses a method for cookware placement onto the cooktop heating zones with the automated cooking control loop. The method uses readings at least from the thermal sensor, 1-, 2- or 3-axis-accelerometer, microphone, wire, wire loop, or any other sensor, and heating power short pulses generating respective magnetic and/or electric field pulses, modulations and cookware vibrations for placement identification. These power pulses for magnetic vibrations are needed to be much shorter than using power pulses to imply temperature changes for placement. As the complement, a cookware type is disclosed having the implemented thermal sensor wire and the accelerometer or microphone or wire loop.
Furthermore, the method checks the placement state frequently thus allowing for the cooking system to know the actual state.
This method and cookware can be used in the cooking system either with an external device/app in the automated control loop or without it in the local mode/local control loop. The indication of the cookware placement on the cooktop can be messaged to the operator/cook by simple sound signals or visual indications, e.g. light, or similar means, or displayed on a smart device (e.g., visually, graphically).

BRIEF DESCRIPTION OF DRAWINGS

To understand cookware placement and appreciate its practical applications, the following pictures are provided and referenced hereafter. Figures are given as examples only and in no way should limit the scope of the invention.

FIG. 1 Depicts a cooking system comprising a cooktop with its digital control module, cookware with the digital control module and external device/app, all the devices working in the automated control loop of the cooking process.
FIG. 2 shows the exploded view of cookware having the bottom plain with integrated thermal sensor wire, wire or wire loop that serves as the sensor to measure the strength of the alternating magnetic and/or electric field received from the induction coil of the cooktop heating area.
FIG. 3 shows the heating power signal from the cooktop induction coil measured by the cookware wire loop; the signal is modulated with the purpose to identify cookware placement on the cooktop surface and heating zones.

DRAWINGS - Reference Numerals

1: Cooktop;
2: Cookware item;
3: External device/app for remote control of the cooking process;
4: Cooktop surface;
5: Induction coil in the heating area of the cooktop;
6: Controller of the heating coil;
7: The manual control panel or User interface panel (UIP);
8: The digital control module in the cooktop;
9: Digital control block (processor and connections to the cooktop)
10: Wireless communication block in the cooktop;
11: A thermal sensor in the cookware;
12: 1-, 2- or 3-axis-accelerometer or microphone in the cookware;
13: Wire or wire loop in the cookware bottom plain for measuring magnetic and/or electric field strength;
14: The digital control module in the cookware item (e.g., in the handle);
15: Wireless communication block in the cookware item (in the digital control module);
16: Cookware detections pulses in the heating power signal;
17, 18, 19, 20: - heating power levels and respective amplitudes of the measured signal.

DETAILED DESCRIPTION

This description discloses details of the cookware placement method and modifications of a smart cooking system needed for using this method.
The present invention serves for a cooking system with multiple cookware items 2 having sensors and a cooktop 1 with several heating zones, or even a cluster of several cooktops, for example in a shared kitchen. Additionally but not necessarily, the system may comprise an external device/application 3 (e.g., smartphone, tablet, touchscreen device, etc.) in the automated temperature control loop of the cooking process.
The problem solved is to know the cookware 2 placement on the cooktop 1 heating zones. It is necessary to arrange the cooktop 1 heating coils 5 to produce a correct amount of magnetic induction and, therefore, to generate heat in the magnetic base layer of the cookware 2. Correspondingly, the cooktop 1 has to know how and what cookware items 2 are placed on the heating zones above their induction coils 5.
Most induction cooktops have integrated the "pot detect" feature allowing the cooktop to detect if any cookware item (pot, pan, a bowl) is placed onto a heating area/zone. The cooktop controller shortly turns-on the heating power and checks if the supplied power is consumed by some cookware in the heating area. If the supplied power is not consumed, then the cookware placement state of that heating area is set to "pot not detected". However, this feature allows the cooktop only to identify which heating areas are occupied with cookware items. It does not allow to the cookware items and external devices/app to know which cookware item 2 is placed on which heating area/coil 5 and if the placement is correct (right above the heating coil).
To identify which cookware item 2 is on which heating area of the cooktop, the changes in cooking temperature inside the cookware item can be exploited. Cookware 2 with an integrated thermal sensor 11 reads the recent cooking temperature and then the automated temperature control loop 15 can identify which heating area provides temperature changing in which cookware item 2. However, such identification by the changing temperature is far not sufficient because temperature changes in the cookware are delayed by at least several or more seconds after the heating power pulse was applied. Another problem is that when cookware has reached the maximum temperature that cannot be increased, the decrease of temperature after switching-off the heating power is prolonged and even less practical to identify the cookware placement.
Therefore, a more robust and effective means are employed in the present method. A prerequisite to apply this method is the cooking system comprising a cooktop 1 having an integrated digital control module 8 with wireless connection means 10 and cookware items 2 having digital control modules 14 with wireless connection means. Also, an automated control loop 15 has to operate between the cooktop 1 and cookware items 2, for example, for automatic control of the cooking temperature. The control loop 15 may also include an external device/app 3, e.g., a smartphone, a tablet or other external control devices.
Further, cookware 2 items are supposed to have at least one additional sensor (e.g., 12, 13) allowing to detect and register the induction coil 5 magnetic signal faster than the thermal sensor 11 can do this by registering temperature changes only. The highest frequency of the alternating magnetic field from the induction coil is the heating resonance frequency of several tens of kilohertz (e.g. in a cooktop the resonance frequency for induction heating can be as high as 26,5kHz or even more). Also, this heating power signal can be modulated by different power amplitude levels and frequencies of tens or hundreds of Hertz, which is a much higher frequency than the maximum rate of cooking temperature changes. Also, this heating power signal can be modulated by power line frequency, e.g., 50Hz. Also, use of signals of a very low frequency, e.g. 1Hz or 0.5Hz, caused by turning on and off a heating zone, and detecting the timing of these events in the pot 2 can be employed for identification of the cookware 2 placement. Therefore, additional sensors can be used to register these different signals, thus assisting for sufficient identification of cookware placement.
In general, different modulation types of heating power signals can be used. It can be advantageous to choose using some "artificial" patterns for modulation of the heating power signal, e.g. a pseudo-random sequence that can be detected by the pot/system but not confused with some extrinsic noise like stirring the pot contents by the user/cook, etc.
Additionally, a different random modulation of the power signal can be used on each heating area, thus making the heating zones to have their heating power "signature". This also is helpful for the identification of cookware items placed onto different heating areas of the cooktop or even several cooktops (e.g., in a shared kitchen).
A sample of a magnetic signal with "amplitude modulation" is presented in FIG. 3. It was obtained from the alternating induction of a heating coil by measuring with a wire loop integrated into the cookware, such as a specially implemented wire loop or an energy harvesting coil, a thermal or other sensor and the associated wire or wires, or any additional embodiment of wire loop being applicable for measuring the magnetic strength signal. Alternatively or additionally, a single wire or wire loop or any other type sensor can be used to measure the strength of the induced electric field. The resonant frequency of the induction circuit, coil and pot is, e.g., 25.8 kHz. The power levels selected or driven by the temperature control loop 15 also affects the amplitude of these pulses. The first narrow pulses 16 are the cookware detection pulses. The subsequent wider pulses 17, 18, 19 with different magnitudes are heating pulses set for different power levels from 1800W to 530W. The power last pulse 20 with discontinuities corresponds to the heating the cookware below a certain power level (e.g. < 350W). This duty cycle period is in the order of seconds, e. g., the heating power is off for 0.25 seconds and on for 1.75 seconds.
For the cookware placement identification, different additional sensors can be implemented in cookware items, such as:

1) An accelerometer 12 mounted or integrated to the cookware item 2, for example, in the handle of the cookware item (FIG. 1).
2) A wire loop 13 implemented in the bottom plain of the cookware item (FIG. 2). It can also be any sensor and/or the associated wires connected by the loop. Said wire loop 13 allows us to measure changes of magnitude of the alternating magnetic field received from the induction coil 5. The advantage is more robust and faster detection of cookware placement, by correlating the power setpoint from the heating control loop, with the magnetic field strength measured by the sensor in the cookware item.
3) Alternatively or additionally, a single wire or wire loop or any other type sensor can be used inside the cookware to measure the strength of the induced electric field.

Additionally, in the digital control modules and devices (8, 14, 3) of the cooking system the additional variables/parameters are defined and employed for identification and detection of cookware placement on the cooktop. The list of the variables comprises at least these variables:

"Pot detect", values:
- ∘ "True" (pot detected),
- ∘ "False" (pot not detected);
"Moving-placed", values:
- ∘ "True" (placed or "standstill"),
- ∘ "False" (moved or moving);
"Placed-Heated/vibrated", values:
- ∘ "True" (placed and "heated/vibrated")
- ∘ "False" (placed and not heated/vibrated),
"Heating/vibration/Off-placed", values:
- ∘ "True" (placed and "heated/vibrated"),
- ∘ "False" (placed and not heated/vibrated);
"Heating_temperature_rate_of_change" variable with numeric values. At the beginning of heating (at high power On or Off) there is observed a change of rate (the 2'nd order derivative) of the temperature. It is estimated with a longer delay (because the temperature measurement is rather extended in time, i. e., 5-10 seconds). But in correlation with this variable, the probability is additionally corrected for identification of the cookware placement on the heating zone.

When the cookware is placed onto a level surface, e.g., the cooktop surface, and afterwards not moved by a hand and not vibrated by the induction coil (no heating power yet), then the measured 3-axis-acceleration vector equals to the constant gravitation vector. This is identified by the 3-axis-accelerometer vector being equal to 1G in the correct stance of placement, and the variable is set: "Moving-placed"="True". Thus it is known that all the following is true:

1) The cookware item 3 is on a level surface (not stacked in the drawer, or the kitchen sink with the handle balancing on the side of the sink).
2) The user/cook is not carrying/moving the cookware item 3: it is difficult to do without disturbing the vector so that motion was not detected.
3) The cooktop is not heating the cookware item 3 at the high power level to disturb the accelerometer 12.

Meanwhile, the wire-loop 13 integrated into the bottom plain of the cookware 2 (FIG. 2) measures the zero-level magnetic field, which is identified as the noise-floor of the signal (FIG. 3).
When the variable "Moving-placed" equals "true/standstill" (i.e., the cookware item is on the level surface 4 of the cooktop 1 which might be covering one or more heating zones) then its transition from "False" to "True" is then correlated/combined with a "Pot detect" signal on this heating zone measured by the cooktop coil 5. "Pot detect" is identified by providing a test power pulse into the coil and if the induction energy flows from the coil, then the "Pot detect" is set to "True". Therefore, when these two signals "Moving-placed" equals "true/standstill" and "Pot detect" = "True" are close in time, i.e., followed one by another - this event suggests a high probability that the cookware item 2 is placed by the user/cook onto the corresponding heating zone 5 of the cooktop 1.
When heating power is turned on, in a digitally controlled induction cooktop, it can be done at high power in the beginning for a specified interval of time (to reach the right cooking temperature quickly). The "Moving-placed" variable transits from "True" to "False" because of the heating vibration. When this change happens in time just after the start of the heating pulse (caused by cooktop control algorithm), the "Placed-Heated/vibrated" variable is assigned with a high probability.
"Heating-off vibration placed": the digital control algorithm turns-off the heating power from the induction coil for a short time in some situations to detect the standstill transition becoming TRUE in correlation with the heat pulse turning off. This can be done, e. g., after a few seconds of heating right after turning on (described in the previous paragraph).
"Heating Temperature rate of change": at the beginning of the heating (at high power On or Off) there is observed a change of rate (the 2'nd order derivative) of the temperature. This happens with a bit longer delay (because the temperature measurement is rather slow, i. e., 5-10 seconds). But this correlation adds to the probability of the cookware being situated in this zone.
The listed variables and their control functions are implemented in the method and the respective algorithm of cookware placement, producing a reliable detection of the various situations in the kitchen and the cookware placement on the cooktop surface and the heating induction zones.
The cookware placement detection cycles can be initiated frequently and at various times, i.e., at the beginning of heating, after placement/movement of cookware, etc. It can also be initiated again if the probability of a cookware placement state drops below a certain level. This can happen, e. g., when cookware becomes too hot. Then the digital control module 8 reduces the power allowed to all cooking zones (so-called "Safe Reduce" function) this event can help detect placement of cookware items by using both "standstill" signal and temperature change signal.
"Removing cookware item from the heating zone": if "Pot detect" signal turns "False" at the same time as the "Moving-placed" variable turns "False" - this is a reliable indication of that "this pot is not placed on this heating zone anymore". No pot is placed on the heating zone when "pot detect" is false, but the correlation of both signals means this pot was placed until the moment and afterwards moved away from the heating zone.
"Moving a cookware item from one heating zone to another": when the above "removal of cookware from the heating zone" happens and afterwards a new "Pot detect" signal on another heating zone becomes "True" together in time with "Moving-placed" variable of this pot. Then there is an even higher probability for this pot to have been moved from the first heating zone to another heating zone.
The above principles of placement detection can also be used on a cooktop without the "Pot detect" signal where the heating coil is active always after Power-On in that heating area. Some induction cooktops provide the "Pot not detected" signal only when that particular heating zone is turned on. The activated heating zone will not provide heating power unless there are cookware present and the signal "pot is not detected" is received after a second or so. But the speed of detection and the robustness of how easily the detection algorithm can fail is less that means the "Safe Reduce" function needs to be activated more often that leads to the control algorithm initiating a longer detection cycle "all heating zones off - and detect one by one".
The above principles are applicable from sensor signals available as above:

"No pot on coil" - a coil detects no pot is present, the signal comes from the coil power driver module in some cooktops.
"Accelerometers" - detects movement by a user and/or vibration from coil/field. It also detects cookware placed on a horizontal level surface (by the angle of gravity).
"Magnetic field" - measured strength of the alternating magnetic field measured by the wire loop, thermal or other sensor and associated wire or wires, or the energy harvesting coil implemented in the bottom plain of the cookware item 2.
"Electric field" - alternatively or additionally, a single wire or wire loop or any other type sensor can be used inside the cookware to measure the strength of the induced electric field.
"Temperature" - also changes with the induction field strength applied to the pot. Not as straightforward as the field detect because the temperature is affected by many other factors, e.g. contents of the pot, adding the food, stirring food, etc.

The placement method requires physical modifications of cookware and respectively developed software in the digital control devices and modules of the cooking system (digital control module of the cooktop, digital control module of the cookware, and application software in the external device/app).
One embodiment of the cookware comprises a separate coil, especially for measuring the magnetic field strength from the cooktop induction coil.
Another embodiment of the cookware comprises the energy harvesting coil 13 that is used for energy harvesting from the cooktop induction coil 5 but can also be exploited for measuring the magnetic field strength from the induction coil (FIG.2).
One more embodiment of the cookware has integrated one or more 1-, 2-, or 3-axis-accelerometers 12. A single accelerometer can be integrated into the handle of the cookware (FIG. 1). More than one 3-axis-accelerometers are combined, for example, in two opposite handles of a large pot.
One more embodiment of the cookware 2 has integrated 3-axis-accelerometers 12, thermal sensors 11 and energy harvesting coils 13.
One more embodiment of the cookware 2 has any integrated sensor and the associated wire or wires in the bottom plain of the cookware 2.
One more embodiment takes into account that during the cooking process, the control loop repeatedly changes the power level according to the measured temperature in the pot 2 and the temperature setpoint. Even when cookware is steady on the cooktop, the control loop is maintaining the set temperature; thus the power varies ("oscillates") in a wide range. The history of the past power levels from all active coils is then correlated with the history of previously detected field levels in the cookware items. The result of such calculation is probabilities identifying which cookware item is positioned on each coil/heating area. The "modulation" of power level done by the control loop can be seen as a random modulation; however, it is known by the digital control module in the cooktop. Also, another modulation type can be added to the output of the User Interface panel, e.g., a sine wave modulation or another pseudo-random modulation that can easily be detected by sensors and digital processing algorithms. Any modulation technique could be used.
Additional modulation sources are the user actions, e.g., turning on/off the cooking zone or adjusting the power manually, and/or adding food thereby heating/cooling the pot resulting in changed power demand from the temperature control loop.
In general, measuring the induction field strength in the cookware 2 placed on the cooktop 1 is done by one or more of these means:

1) measuring the cookware 2 physical vibrations caused by the induction field using 1-, 2-, 3-axis accelerometer 12 and/or microphone;
2) measuring the strength of the electric and/or magnetic field in the cookware 2 placed on the cooktop heating zones/coils 5 using:
- a wire loop 13 integrated into cookware specifically for this purpose and/or a harvesting loop 13 that is used for energy harvesting from the heating coil through magnetic inductance;
- the temperature sensor 12 and/or the associated wire or wires;
- any other dedicated sensor and/or the associated wire or wires.

Claims

A method of cookware placement identification by a control loop in an induction cooking system, the method comprising one or more steps of
- Turning-on heating power to the induction coil (5) in at least one heating zone of the cooktop (1),

- Turning-off heating power to the induction coil (5) in at least one heating zone of the cooktop (1),

- Modulating heating power to the induction coil (5) in at least one heating zone of the cooktop (1),

- Reading temperature values from a thermal sensor (11) integrated into cookware item (2),

- Reading other type measurement values from one or more sensors (11, 12, 13) integrated into cookware item (2),
characterized in that
- said one or more sensors (11, 12, 13) register strength of at least one of the alternating magnetic and electric fields of the heating induction in at least one heating zone (5) of the cooktop (1);

- the present state of cookware (2) placement on the cooktop (1) surface and heating zones (5) is identified by modulating the heating induction to the induction coil (5) and analysis of readings (16, 17, 18, 19, 20) of said strength of at least one of the alternating magnetic and electric fields from said one or more sensors (11, 12, 13), wherein said one or more sensors (11, 12, 13) comprises said thermal sensor (11) or other sensors, wire, wires (12, 13) or combination thereof.
The method according to claim 1, characterized in that said sensor is at least one 1-, 2- or 3-axis-accelerometer (12) or a microphone mounted on or integrated into the cookware (2) to register said strength of the alternating magnetic field by the cookware (2) physical vibrations.
The method according to claim 1, characterized in that the sensor is a wire-loop that is used for energy harvesting (13), the temperature sensor (11) and associated wire or wires, or any other dedicated sensor or wire loop with the associated wires, integrated in the bottom plain of cookware for measuring strength of at least one of the magnetic and electric field signals received from the induction coil (5).
The method according to claims 1 to 3, characterized in that values from the sensors (11, 12, 13) are read-out repeatedly or on-demand by a predefined time interval and updated to all or some of the intelligent devices in the automated temperature control loop, such as the cooktop (1), cookware items (2), and external devices/apps (3).
The method according to claims from 1 to 4, characterized in that historic data of the 1-, 2- or 3-axis-accelerometer (12) or microphone of claim 2, wires or wire loops (13) of claim 3 and thermal sensors (11) of claim 1 is collected, arranged and stored into the cookware digital module (14) for more precise identifications of the cookware placement state and detection of the state changes.
The method according to claims 1 to 5, characterized in that the detected change of the cookware (2) placement state is indicated to the user via means of external signaling, at least, sound and light indicators, functional displays.
The method according to claims 1 to 6, characterized in that the detected change of the cookware placement state is used to modify the signals used by the control algorithms for controlling the power for the heating zones.
The method according to claims 1 to 7, characterized in that the amplitude modulation, phase modulation, and digital modulations are applied to the heating power signal and signal processing algorithms to identify the cookware (2) placement on the cooktop (1).
The method according to claims 1 to 7, characterized in that the heating power modulations by the temperature control loop caused by user's actions directly to Manual Control Panel (7) or indirectly through addition or stirring hot/cold food, are used to identify the cookware (2) placement on the cooktop (1).
A cooking system comprising a cooktop (1) having an integrated digital control module (8) with wireless connection means (10) and cookware items (2) having digital control modules (14) with wireless connection means, wherein an automated control loop (15) is operating between the cooktop (1) and the cookware items (2) for automatic control of the cooking temperature;
wherein said cookware items (2) comprise an integrated thermal sensor (11) configured to read the recent cooking temperature;
characterized in that said cookware items (2) comprise at least one additional sensor (12, 13) configured to detect and register the induction coil (5) magnetic signal faster than the thermal sensor (11) can do this by registering temperature changes only.
The cooking system of claim 10, wherein the control loop (15) includes an external device/app (3), e.g., a smartphone, a tablet or other external control devices.
The cooking system of claim 10 or 11, wherein said at least one additional sensor (12, 13) is configured to detect signals from 0.5Hz to 26.5kHz, such as 0.5Hz, 1Hz, 50Hz, 25.8kHz or 26.5kHz.
The cooking system of any of claims 10 to 12, wherein said at least one additional sensor (12, 13) is a 1-, 2- or 3-axis-accelerometer (12) or a microphone mounted on or integrated into the cookware (2) to register said strength of the alternating magnetic field by the cookware (2) physical vibrations, or a wire-loop that is used for energy harvesting (13), the temperature sensor (11) and associated wire or wires, or any other dedicated sensor or wire loop with the associated wires, integrated in the bottom plain of cookware for measuring strength of at least one of the magnetic and electric field signals received from the induction coil (5).
The cooking system of any of claims 10 to 13, wherein the automated control loop (15) is configured to apply amplitude modulation, phase modulation or digital modulation to the heating power signal and the cooking system comprises signal processing algorithms to identify the cookware (2) placement on the cooktop (1).