Induction cooking device and control method thereof

Abstract

The present invention relates to an induction cooking device (1) and a control 5 method for the induction cooking device (1). The induction cooking device (1) comprises a top plate (2), at least one induction coil (3) disposed under the top plate (2), an inverter circuit (4), an infrared sensor (5) disposed under the top plate (2), a first temperature sensor (6), and a control unit (7) configured to receive temperature data from the infrared sensor (5) and the first temperature 10 sensor (6), and obtain cooking container information indicating type of the cooking container. The control unit (7) is operable to control an output of the inverter circuit (4) according to received data and obtained information.

Description

[0001] INDUCTION COOKING DEVICE AND CONTROL METHOD THEREOF

[0002] Technical Field

[0003] The present invention relates to an induction cooking device and control method for the induction cooking device.

[0004] Background of the Invention

[0005] Induction cooking devices operate according to the principle of heating a cast iron or steel ferromagnetic cooking vessel with a magnetic field generated by an induction coil. Cooking temperature is an important parameter which should be accurately monitored and controlled during the cooking process for consistently achieving desired cooking results, as well as for purposes of energy efficiency. Known temperature sensing means for detecting temperature of a cooking utensil or that of the food being cooked comprise temperature sensing devices placed on a top plate of the cooking device, and those attached to or inserted into the cooking utensil. Devices used in these ways, however, physically intervene with the cooking utensil and food, posing safety risks for users. Furthermore, being subject to humidity, heat, oil, and food during cooking process, sensing sensitivity of these devices deteriorate in time, which in turn leads to undesired cooking results and reduced energy efficiency.

[0006] In the state of the art, Chinese patent application no. CN114060866A discloses a temperature measuring device for a gas stove. The measuring device comprises an image acquisition unit and an infrared radiation monitoring unit for measuring a cooking temperature of cookware. Another prior art document, United States patent application no. US2018135863A1 discloses a cooker hotplate control system for maintaining foodstuff at a preset temperature. The control system comprises an infrared sensor and a temperature sensor for determining temperature of foodstuff or a vessel containing the same.

[0007] Aim

[0008] The aim of the present invention is to overcome the shortcomings of prior art by realization of an induction cooking device and a control method for an induction cooking device, wherein actual temperature of foodstuff being cooked can be determined and controlled accurately. Another purpose of the present invention is to provide an induction cooking device and control method that improves cooking experience regardless of the content and amount of food being cooked, type of cookware used, or method of cooking. A further purpose of the invention is realizing a cooking device and method wherein energy efficiency is increased.

[0009] Brief Description of the Invention

[0010] The induction cooking device realized in order to attain the aims of the present invention is explained in Claim 1 and the respective claims thereof. The induction cooking device comprises: a top plate; at least one induction coil disposed under the top plate, operable to perform induction heating of a cooking container placed on the top plate; an inverter circuit operable to supply high frequency current to the induction coil; an infrared sensor disposed under the top plate, for measuring a combined temperature by detecting amount of infrared light radiated from the top plate and the cooking container; a first temperature sensor for detecting a temperature of the top plate; and a control unit configured to receive temperature data from the infrared sensor and the first temperature sensor, and obtain cooking container information indicating type of the cooking container. The control unit is operable to control an output of the inverter circuit.

[0011] In the preferred embodiment of the present invention, the induction cooking device further comprises a detection unit for detecting current electrical operation parameters of the induction cooking device and transmit said electrical parameters to the control unit. And the control unit is configured to: determine, based on a predefined dataset, temperature of the food being cooked in the cooking container, by using the temperature data, cooking container information, and current electrical parameters; and control the output of the inverter circuit such that the food temperature is brought to and kept at a target cooking temperature. Using temperature data comprising measurement data from both the infrared sensor and the first temperature sensor allows distinguishing amount of heat radiated by the top plate and thus temperature of the cooking container can be reliable inferred. Furthermore, by taking the cooking container information, and particularly the type of the cooking container into account, food temperature can be more accurately determined by regardless of the type of cooking container used. Monitoring and employing electrical operating parameters of the induction cooking device helps differentiating between thermal responses due to differences in amount of food and also method of cooking, and hence obtaining a more refined food temperature result.

[0012] According to an embodiment, the first temperature sensor is also disposed under the top plate such that the first temperature sensor is operable to detect temperature of the top plate by thermal conduction. The first temperature sensor may comprise a negative temperature coefficient (NTC) thermistor.

[0013] The induction cooking device may further comprise a second temperature sensor for detecting ambient temperature, and the temperature data may further comprise the ambient temperature information. By considering the ambient temperature, in addition to temperature data from the infrared sensor and the first temperature sensor, possible effects of variations in ambient temperature on measurements and calculations are eliminated. Thus, accuracy of determined food temperature can be further improved

[0014] The electrical operation parameters of the induction cooking device may comprise instant electrical power supplied by the induction cooking device and / or induction coil driving frequency.

[0015] In at least some embodiments, the control unit is configured to determine type of container by operating the induction cooking device, before starting the cooking, according to a predetermined routine and by assessing the temperature of the container at the end of the routine.

[0016] The predefined dataset used by the control unit in determining the temperature of food may be a machine-learned model configured to output a food temperature value based on input data comprising temperature data, cooking container information and current electrical parameters. According to another aspect of the present invention, there is provided a control method for the induction cooking device. The method comprises: obtaining, by the control unit, temperature data detected by the infrared sensor and the first temperature sensor; obtaining, by the control unit, cooking container information indicating type of the cooking container; detecting, by the detection unit, current electrical operation parameters of the induction cooking device; determining, by the control unit, based on a predefined dataset, temperature of the food being cooked in the cooking container by using the temperature data, cooking container information, and current electrical parameters; and controlling, by the control unit, the output of the inverter circuit such that the food temperature is brought to and kept at a target cooking temperature.

[0017] Brief Description of the Drawings

[0018] The induction cooking device realized in order to attain the aim of the present invention is illustrated in the attached figures, where:

[0019] Figure 1 is a schematic block diagram of an induction cooking device according to an embodiment of the invention,

[0020] Figure 2 is a perspective view of an induction cooking device and its top plate according to an embodiment of the invention,

[0021] Figure 3 is a perspective view of an induction cooking device with the top plate removed, according to an embodiment of the invention,

[0022] Figure 4 is a perspective view of middle part of the induction cooking device comprising induction coils and temperature sensing means, according to an embodiment of the invention,

[0023] Figure 5 is a graphic illustrating an exemplary routine for determining cooking container type,

[0024] Figure 6 is a schematic representation of a machine-learned model used in an embodiment of the invention,

[0025] Figure 7 is a set of experimental results illustrating the performance responses of the present invention for various set temperatures and cooking container types. List of Parts

[0026] The elements illustrated in the figures are numbered as follows:

[0027] 1. Induction cooking device

[0028] 2. Top plate

[0029] 3. Induction coil

[0030] 4. Inverter circuit

[0031] 5. Infrared sensor

[0032] 6. First temperature sensor

[0033] 7. Control unit

[0034] 8. Detection unit

[0035] Detailed Description of the Invention

[0036] The induction cooking (1) comprises a top plate (2); at least one induction coil

[0037] (3) disposed under the top plate (2), operable to perform induction heating of a cooking container placed on the top plate (2); an inverter circuit (4) operable to supply high frequency current to the induction coil (3); an infrared sensor (5) disposed under the top plate (2), for measuring a combined temperature (T1) by detecting amount of infrared light radiated from the top plate (2) and the cooking container; a first temperature sensor (6) for detecting a temperature (T2) of the top plate (2); and a control unit (7) configured to receive temperature data from the infrared sensor (5) and the first temperature sensor (6), and obtain cooking container information indicating type of the cooking container, wherein the control unit (7) is operable to control an output of the inverter circuit

[0038] (4). (Figures 1 and 2)

[0039] The induction cooking device (1) further comprises a detection unit (8) for detecting current electrical operation parameters of the induction cooking device (1) and transmit said electrical parameters to the control unit (7). The control unit (7) is configured to determine, based on a predefined dataset, temperature (Tf) of the food being cooked in the cooking container, by using the temperature data, cooking container information, and current electrical parameters. The control unit (7) is configured to control the output of the inverter circuit (4) such that the food temperature (Tf) is brought to and kept at a target cooking temperature.

[0040] The infrared sensor (5) is placed under the top plate (2) such that it can sense infrared light radiated from both the cooking container and the top plate (2), withouth contacting the top plate (2). Accordingly, the infrared sensor (5) can measure a combined temperature (T1) wherein heat radiating from both the cooking container and the top plate (2) are involved. The first temperature sensor (6), which is also preferably placed under the top plate (2), is operable to directly measure the temperature (T2) of the top plate (2).

[0041] Since the temperature data includes both the combined temperature (T1) and temperature (T2) of the top plate (2), it is possible to accurately determine temperature of the cooking container and use the same in determining food temperature (Tf).

[0042] The induction cooking device (1) may comprise a plurality of induction coils (3) of rectangular and / or circular shape. One or more cooking zones for placing a cooking container may be defined on the top plate (2). Each cooking zone may be heated by one or more induction coils (3) placed underneath the respective cooking zone. The infrared sensor (5) and the first temperature sensor (6) may be disposed next to one another, close to the edge or at a dedicated recess in the middle of an induction coil (3). The infrared sensor (5) and the first temperature sensor (6) may additionally or alternatively be disposed, in case of cooking zone having a plurality of induction coils (3), between said plurality of induction coils (3). Figures 3 and 4 illustrate an exemplary embodiment of such a configuration.

[0043] In determining temperature (Tf) of the food being cooked in the cooking container, the control unit (7) makes use of the temperature data (T 1 , T2), cooking container information, and current electrical parameters. By employing a predefined dataset comprising a range of temperature data (T 1 , T2), cooking container information, and electrical parameters measurements obtained experimentally, a corresponding food temperature (Tf) can be determined. Given that different types of cooking utensils have varying emissivity characteristics, making use the container type information helps further improving accuracy of measured temperatures, such as the combined temperature (T1), temperature of the cooking container, and the food temperature (Tf).

[0044] In an embodiment, the induction cooking device (1) further comprises a second temperature sensor (not shown in figures) for detecting ambient temperature (T3). The temperature data may further comprise the ambient temperature (T3) information. Accordingly, the temperature data used in determining the food temperature (Tf) comprises a combined temperature (T1) of the cooking container and the top plate (2), temperature (T2) of the top plate (2) as measured by the first temperature sensor (6), and preferably the ambient temperature (T3).

[0045] The electrical operation parameters may comprise instant electrical power (w) supplied by the induction cooking device (1) and / or driving frequency (f) of the induction coil (3). Instant electrical power (w) gives an indication of the power transferred to the cooking container, depending on power settings of the induction cooking device (1) at a given time. As a further electrical parameter that affects the amount of heat transferred from the induction cooking device (1) to the cooking container, operating frequency (f) of an induction coil (3) at said given time can additionally be taken into account in determining the food temperature (Tf).

[0046] The control unit (7) may be configured to obtain cooking container information directly from a user of the induction cooking device (1), for example a user inputting the type of used cooking container via a user interface of the induction cooking device (1). Additionally, or alternatively, the control unit (7) may be configured to automatically determine type of container, for example by operating the induction cooking device (1), at the outset of or before starting the cooking, according to a predetermined routine and by assessing the temperature of the container at the end of the routine. According to an embodiment, the routine comprises operating the induction cooking device (1) for a plurality of predetermined time periods (t1 , t2, t3) at respective predetermined frequencies (f1 , f2, f3), and type of container can be determined by assessing within which one of a predetermined temperature intervals the temperature of the container at the end of the routine is.

[0047] The control unit (7) may be further configured to determine a gain factor (K) corresponding to the type of cooking container. The cooking container information may then comprise said gain factor (K).

[0048] In an exemplary embodiment wherein the control unit (7) automatically determines type of the cooking container by applying a predetermined routine, the control unit (7) controls the inverter circuit (4) to operate an induction coil (3) at a first frequency (f1) for a preset first time period (t1), at a second frequency (f2) for a preset first time period (t2), and at a third frequency (f3) for a preset first time period (t3). (Figure 5) The control unit (7) calculates the temperature of the cooking container at the end of said routine, that is, at a time point t1+t2+t3, and compares said temperature to a plurality of preset temperature ranges. In the example illustrated in Figure 5, each one of temperature intervals (O-Ta), (Ta-Tb), and (>Tb) correspond to a category of cooking container. In a hypothetical case where four cooking containers (S1 , S2, S3, S4) are evaluated, the control unit (7) would thus judge by assessing the respective reached temperatures at t1+t2+t3 that S1 is category A; S2 and S3 are category B; and S4 is category C type container. The control unit may further determine a corresponding gain factor (K1 , K2, K3) for a respective container type, and the determined gain factor can be used in calculating food temperature (Tf).

[0049] The predefined dataset may contain the cooking container type / category information and / or the corresponding gain factor.

[0050] In at least some embodiments of the invention, the predefined dataset is a machine-learned model configured to output a food temperature (Tf) value based on input data comprising temperature data (T1 , T2, T3), cooking container information (K) and current electrical parameters (w, f). (Figure 6) The machine-learned model can be a system modelled by collecting temperature data, container information and electrical operating parameters; as well as realtime food temperature information under various conditions and trained by using an artificial neural network.

[0051] As illustrated in figures 7a, 7b and 7c, performance responses (T(m)) of the present invention at various set temperatures (85°C, 100°C and 180°C, respectively) are in line with actual measured food temperatures (T(f)).

[0052] The method for the induction cooking device (1) comprises obtaining, by the control unit (7), temperature data detected by the infrared sensor (5) and the first temperature sensor (6), obtaining, by the control unit (7), cooking container information indicating type of the cooking container, detecting, by the detection unit (8), current electrical operation parameters of the induction cooking device (1), determining, by the control unit (7), based on a predefined dataset, temperature of the food (Tf) being cooked in the cooking container by using the temperature data, cooking container information, and current electrical parameters, and controlling, by the control unit (7), the output of the inverter circuit (4) such that the food temperature is brought to and kept at a target cooking temperature.

[0053] In some embodiments, the predefined dataset is a machine-learned model configured to output a food temperature (Tf) value based on input data comprising temperature data (T 1 , T2, T3), cooking container information (K) and current electrical parameters (w, f).

[0054] Obtaining cooking container information may comprise determining type of container by operating the induction cooking device (1), before starting the cooking, according to a predetermined routine and by assessing the temperature of the container at the end of the routine. Determining type of container may comprise assessing within which one of a predetermined temperature intervals the temperature of the container at the end of the routine is. By means of the induction cooking device (1 ) and control method of the present invention, temperature of a cooking container and the temperature (Tf) of food in the container is accurately determined. As the food temperature (Tf) is closely monitored during cooking, the cooking process can be controlled such that the food temperature (Tf) is brought to and maintained precisely at a target cooking temperature. In this way, regardless of the content and amount of food being cooked, type of cookware used, or method of cooking; cooking performance and energy efficiency of the induction cooking device (1) is improved.

Claims

CLAIMS1. An induction cooking device (1) comprising: a top plate (2); at least one induction coil (3) disposed under the top plate (2), operable to perform induction heating of a cooking container placed on the top plate (2); an inverter circuit (4) operable to supply high frequency current to the induction coil (3); an infrared sensor (5) disposed under the top plate (2), for measuring a combined temperature (T1) by detecting amount of infrared light radiated from the top plate (2) and the cooking container; a first temperature sensor (6) for detecting a temperature (T2) of the top plate (2); and a control unit (7) configured to receive temperature data from the infrared sensor (5) and the first temperature sensor (6), and obtain cooking container information indicating type of the cooking container, wherein the control unit (7) is operable to control an output of the inverter circuit (4); characterised in that the induction cooking device (1) further comprises a detection unit (8) for detecting current electrical operation parameters of the induction cooking device (1) and transmit said electrical parameters to the control unit (7), and the control unit (7) is configured to: determine, based on a predefined dataset, temperature (Tf) of the food being cooked in the cooking container, by using the temperature data, cooking container information, and current electrical parameters, and control the output of the inverter circuit (4) such that the food temperature (Tf) is brought to and kept at a target cooking temperature.

2. The induction cooking device (1) according to claim 1 , wherein the first temperature sensor (6) is disposed under the top plate (2) such that the first temperature sensor (6) is operable to detect temperature of the top plate (2) by thermal conduction.

3. The induction cooking device (1) according to claim 1 or 2, wherein the induction cooking device (1) further comprises a second temperature sensor for detecting ambient temperature (T3), and the temperature data further comprises the ambient temperature information.

4. The induction cooking device (1) according to any one of preceding claims, wherein the electrical operation parameters of the induction cooking device (1) comprise instant electrical power (w) supplied by the induction cooking device (1) and / or induction coil (3) driving frequency (f).

5. The induction cooking device (1) according to any one of preceding claims, wherein the control unit (7) is further configured to determine type of container by operating the induction cooking device (1), before starting the cooking, according to a predetermined routine and by assessing the temperature of the container at the end of the routine.

6. The induction cooking device (1) according to claim 5, wherein the routine comprises operating the induction cooking device (1) for a plurality of predetermined time periods (t1 , t2, t3) at respective predetermined frequencies (f1 , f2, f3).

7. The induction cooking device (1) according to claim 5 or 6, wherein the control unit (7) is further configured to determine type of container by assessing within which one of a predetermined temperature intervals the temperature of the container at the end of the routine is.

8. The induction cooking device (1) according to any one of preceding claims, wherein the control unit (7) is further configured to determine a gain factor (K) corresponding to the type of cooking container, and the cooking container information comprises said gain factor (K).

9. The induction cooking device (1) according to any one of preceding claims, wherein the predefined dataset is a machine-learned model configured to output a food temperature (Tf) value based on input data comprising temperature data, cooking container information and current electrical parameters.

10. A control method for an induction cooking device (1) according to any one of preceding claims, wherein the method comprises:obtaining, by the control unit (7), temperature data detected by the infrared sensor (5) and the first temperature sensor (6), obtaining, by the control unit (7), cooking container information indicating type of the cooking container, detecting, by the detection unit (8), current electrical operation parameters of the induction cooking device (1), determining, by the control unit (7), based on a predefined dataset, temperature of the food (Tf) being cooked in the cooking container by using the temperature data, cooking container information, and current electrical parameters, and controlling, by the control unit (7), the output of the inverter circuit (4) such that the food temperature is brought to and kept at a target cooking temperature.

11. The control method according to claim 10, wherein the predefined dataset is a machine-learned model configured to output a food temperature (Tf) value based on input data comprising temperature data, cooking container information and current electrical parameters.

12. The control method according to claim 10 or 11 , wherein obtaining cooking container information comprises determining type of container by operating the induction cooking device (1), before starting the cooking, according to a predetermined routine and by assessing the temperature of the container at the end of the routine.

13. The control method according to claim 12, wherein determining type of container comprises assessing within which one of a predetermined temperature intervals the temperature of the container at the end of the routine is.

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