Microwave heating device and method for operating a microwave heating device

Abstract

The present disclosure relates to a microwave heating device and a method for operating a microwave heating device, specifically for heating at least one product in a heating chamber of the device. The microwave heating device comprises at least two radiating portions, wherein the at least two radiating portions are adapted to radiate microwaves to a heating chamber and are operable according to a plurality of operating configurations, the plurality of operating configurations differing in frequency and / or phase shift between the radiated microwaves. A learning procedure may be performed by sequentially operating the at least two radiating portions in a number of operating configurations. Energy efficiency data is calculated for these operating configurations. An operating frequency may be selected, the selection being based on the energy efficiency data. The operating configuration having the maximum energy efficiency at the selected operating frequency may be considered as a reference operating configuration. A heating procedure may be performed by sequentially operating the at least two radiating portions in an operating configuration having a selected operating frequency and a corresponding phase shift selected around a corresponding phase shift of a reference operating configuration. The phase shift of each selected operating configuration may have a phase shift distance relative to a corresponding phase shift of a reference operating configuration, so that in the space of the phase shifts, the reference operating configuration is surrounded by the selected operating configuration.

Description

[0001] This application is a divisional application of an invention patent application with an application date of March 30, 2017, an international application number of PCT / US2017 / 024934, a national application number of 201780031703.2, and an invention name of “Microwave heating device and method for operating a microwave heating device”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional Application No. 62 / 317,077, filed on April 1, 2016, and U.S. Application No. 15 / 414,075, filed on January 24, 2017, the entire contents of which are incorporated herein by reference. Technical Field

[0004] The present disclosure relates generally to the field of electromagnetic heating. In particular, the present disclosure relates to microwave heating devices and methods for operating microwave heating devices, in particular for defrosting and / or cooking food products. Background Art

[0005] Currently, there are many known and widely used technologies for heating food (for both thawing and cooking purposes).

[0006] According to some known heating technologies, food receives heat via its outer surface, which exchanges heat with an external heating element or an external environment at a higher temperature. In these technologies, the flow of heat within the food is determined by the temperature gradient and thermal diffusivity of the food itself.

[0007] According to other known heating technologies, heat is generated directly in the food by electromagnetic fields or electromagnetic radiation. Among them, some technologies use radio frequency (RF) dielectric heating, and other technologies use microwaves (MW). Traditionally, radio frequency electromagnetic waves are in the frequency band between 1 and 300 MHz, while microwaves are in the frequency band between 300 MHz and 300 GHz. Specifically, radio frequency heating devices and microwave heating devices are known and widely used.

[0008] Electromagnetic heating techniques using radio frequency or microwaves are generally useful for achieving shorter thawing or cooking times than techniques using heat exchange via the food surface. However, a common problem with many known electromagnetic heating techniques involves the difficulty in obtaining a sufficiently uniform distribution of temperature within the food.

[0009] Another problem of the known electromagnetic heating technology is encountered when several identical portions (or parts) of food are heated simultaneously. Under these conditions, it usually happens that the temperatures of these portions of food are not identical to each other at the end of the heating process, i.e., an acceptable spatial heating uniformity cannot be obtained.

[0010] These problems generally appear to be more pronounced with microwave heating devices.

[0011] It is therefore desirable to have a heating technique, in particular using microwaves, which allows reducing the non-uniformity of the temperature distribution in the food and / or between different portions of the food during its heating. Summary of the invention

[0012] Specifically, the present disclosure relates to a heating device and method using microwave heating technology to heat at least one product. In a specific mode of use, at least one product is a food, and the heating is intended to thaw and / or cook the food and / or simply heat the food. However, the heating device and method can also be used for other types of products.

[0013] In some example embodiments, a microwave heating device may include: a heating chamber for receiving at least one product to be heated; a microwave generating system including at least two radiation sections adapted to radiate microwaves to the heating chamber; and a control unit. The microwave generating system may generate corresponding microwaves having the same frequency and different phases, and radiate the corresponding microwaves via at least two radiation sections. Thus, one of the two radiation sections may be considered as a reference radiation section, while the microwaves of the other radiation section (or other radiation sections if there are more than two radiation sections) may have a corresponding phase shift (or multiple phase shifts) relative to the microwaves of the reference radiation section. The operating configuration of the microwave generating system may be defined by the frequency value and the phase shift value(s).

[0014] In some example embodiments, the microwave generating system may include four radiating sections. Thus, each operating configuration may be defined by a frequency value and three phase shift values. The phase combination of the operating configuration may be represented as a point in a three-dimensional space of phase shifts.

[0015] The control unit may be configured to operate the microwave generation system and to change the frequency and phase shift (or phase shifts) of the microwaves radiated by the microwave generation system. Thus, at least two radiating portions may be operated according to a plurality of operating configurations, wherein the plurality of operating configurations have mutually different frequencies and / or phase shifts (or phase shifts) between the radiated microwaves. An energy efficiency inversely proportional to the ratio of reflected power to radiated power is associated with each operating configuration. The microwave heating device may include a reflected power detection system, and the control unit may be configured to calculate this energy efficiency.

[0016] According to one aspect of the present disclosure, the control unit may be configured to operate the microwave generating system in such a way that a "micromotion" of the microwave distribution within the heating chamber may be obtained during a heating program of at least one product. This object may be achieved by sequentially operating the microwave generating system in several operating configurations, each operating configuration having a selected operating frequency and a corresponding phase shift(s) selected around a corresponding phase shift(s) of a reference operating configuration. In other words, virtual micromotions may be generated by a phase rotation method.

[0017] In fact, the change of the phase shift of the microwaves emitted by the radiating portion will require a change in the interference pattern of the microwaves in the heating chamber, and specifically, a shift of the gain interference position and the detrimental interference position. Therefore, the position of the peak of the received radiated power can be moved on the product to be heated or on several parts of the product by using several operating configurations with different phase shifts. This is beneficial to produce a more uniform spatial distribution of electromagnetic heating power in the heating chamber and to improve the spatial uniformity of the amount of electromagnetic energy given to the product or several portions of the product during the heating process.

[0018] One aspect of the present disclosure relates to the selection of an operating configuration to be used in a heating procedure.

[0019] According to some possible methods of use, data on the energy efficiency depending on the operating configuration may be obtained for a product or several portions of a product located in a heating chamber. The obtained data may be processed by a control unit to select an operating frequency and a reference operating configuration, wherein the reference operating configuration is the operating configuration with the maximum energy efficiency at the selected operating frequency. Furthermore, the operating configuration of the heating program may be selected as an operating configuration with the selected operating frequency and a respective phase shift selected around a respective phase shift of the reference operating configuration. More specifically, the phase shift of each selected operating configuration may have a phase shift distance relative to the respective phase shift of the reference operating configuration in such a way that in the space of the phase shifts the reference operating configuration is surrounded by the selected operating configuration.

[0020] The inventors have experimentally verified that the use of an operating configuration selected in accordance with the methods described herein can achieve excellent spatial heating uniformity, particularly when heating multiple identical portions simultaneously.

[0021] It is believed that for each frequency, the energy efficiency generally has a fairly smooth trend between minimum and maximum values ​​as the operating configuration changes. Therefore, these methods of picking the operating configuration for a heating program can be beneficial for micro-moving the microwave distribution without creating any significant differences between the energy efficiencies of the operating configurations used in the heating program. This is beneficial for spatial heating uniformity.

[0022] In some example embodiments, the microwave generating system may include four radiating sections, and thus each operating configuration may be defined by a frequency value and three phase shift values. The operating configuration may be represented as a point in a three-dimensional space of phase shifts. According to one possible method of use, the points of the operating configuration selected for the heating program may be vertices of a polyhedron in the three-dimensional space of phase shifts, and the reference operating configuration may be a point in the body or center of the polyhedron. In a specific method of use, the selected operating configurations are eight operating configurations, and their corresponding points are vertices of a cube centered at the point of the reference operating configuration.

[0023] In other example embodiments, the microwave generating system may include N radiating sections, and thus each operating configuration may be defined by a frequency value and (N-1) phase shift values. According to one possible method of use, the points of the operating configuration chosen for the heating program may be vertices of a hyperpolyhedron in the (N-1)-dimensional space of phase shifts, and the reference operating configuration may be a point in the body or center of the hyperpolyhedron, specifically a hypercube.

[0024] According to some possible methods of use, the phase shift distance can be calculated based on the efficiency difference at the selected operating frequency. The efficiency difference is defined as the difference between the maximum energy efficiency and the minimum energy efficiency that can be found for the operating configuration at the same frequency. More specifically, the phase shift distance can be calculated inversely proportional to the efficiency difference.

[0025] According to some possible methods of use, the operating frequency of the heating program may be selected as a frequency value for which the efficiency difference has a minimum value.

[0026] In some example embodiments, the control unit may be configured to obtain energy efficiency data by running a learning procedure after at least one product has been located in the heating chamber. During the learning procedure, the frequency and the phase shift are changed to sequentially operate the at least two radiation portions in a number of operating configurations. For each frequency, several operating configurations with mutually different phase shifts may be selected and the at least two radiation portions may be operated in these selected configurations. More specifically, during the learning procedure, the frequency is changed within a certain range and for each frequency, several operating configurations with mutually different phase shifts are selected.

[0027] The energy efficiency may be calculated for each of the several operating configurations for the learning procedure and the data of the energy efficiency obtained may be saved. In this way, data of the energy efficiency depending on the operating configuration may be obtained for at least one product in the heating chamber.

[0028] This has the advantage of directly obtaining information about how much at least one product in the heating chamber interacts with the microwaves and how this interaction changes when the frequency and / or the phase shift is changed. In practice, each product introduced in the heating chamber has characteristics different from the other products. Furthermore, the interaction with the microwaves depends on the shape of the product and its position in the heating chamber.

[0029] Specifically, the learning procedure may allow mapping of energy efficiency as a function of frequency and phase shift for a specific group of identical portions to be heated simultaneously. The learning procedure is useful in optimally setting the operating configuration for the group of identical portions in the heating chamber. The short duration of the learning procedure does not affect the overall cooking process, and the learning procedure may be repeated from time to time during cooking without any problems.

[0030] In other words, the learning procedure may implement an adaptive algorithm, wherein the adaptive algorithm allows the heating procedure to be adapted to a specific group of portions to be heated. The data obtained in the learning procedure may be used to select an operating configuration of the heating procedure: during the heating procedure, at least two radiation portions are operated sequentially according to the operating configuration that has been selected based on the data obtained in the learning procedure.

[0031] In other example embodiments, for this specific portion or a group of portions to be heated, energy efficiency data is available to the control unit without the need for a learning program. For example, these data of the same portion or a group of portions have been obtained during a previous learning program and saved so that the control unit can retrieve these data when the same portion or a group of portions need to be heated. In another example, these data can be obtained and processed in the setup phase of the microwave heating device, and saved as a specific recipe for this specific portion or a group of portions. Therefore, the operation of obtaining and processing energy efficiency data can be performed only once for each portion or a group of portions, and a specific recipe can be called to cook the corresponding portion or a group of portions. These example embodiments may be applicable to portions of a specific type that should be placed in certain fixed positions in the heating chamber of a microwave heating device. This may be applicable to industries such as fast food restaurants, in which the range of the product to be cooked is extremely limited, and the portion of the product that can be placed in the same position in the heating chamber is standardized in terms of quality, shape and size. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Having generally described the subject matter of the present disclosure, other features and methods of use will become apparent in the following detailed description of specific embodiments provided by way of example and not limiting the scope of the present disclosure. Reference will be made to the accompanying drawings, which are schematic diagrams not necessarily drawn to scale, in which:

[0033] Figure 1is a schematic diagram of an example embodiment of a microwave heating apparatus according to the present disclosure, some components of which are simply depicted as block elements;

[0034] Figure 2 is a block diagram of a possible method of using a microwave heating device according to the present disclosure;

[0035] Figure 3 is an exemplary graph related to possible methods of using a microwave heating device according to the present disclosure;

[0036] Figure 4 is a block diagram of a possible algorithm for a selection procedure according to the present disclosure;

[0037] Figure 5 yes Figure 4 A schematic diagram of the steps of the selection procedure;

[0038] Figure 6 is with Figure 4 Exemplary graphs related to the selection process;

[0039] Figure 7 is an exemplary graph related to a heating program according to a possible method of using an example embodiment of a microwave heating apparatus of the present disclosure; and

[0040] Figure 8 is an exemplary graph related to a heating procedure of a possible method of using a microwave heating device according to another example embodiment of the present disclosure. DETAILED DESCRIPTION

[0041] An example embodiment of a microwave heating device according to the present disclosure is designated by reference numeral 1 and is schematically illustrated in Figure 1 middle.

[0042] Figure 1 Several components of the heating device 1 are shown in order to make the description easier to understand. Some components are shown with dashed lines only to indicate that they are outside the structure of the heating device 1, in order to achieve a functional representation thereof. However, this figure should not be considered as an accurate and detailed technical drawing to be used for production purposes. Therefore, Figure 1 Not all components of the heating device 1 are shown and should not be considered as drawings that faithfully reproduce the scale and proportions between the components.

[0043] The microwave heating device 1 can be used to heat at least one product 9, in particular at least one food product, for example food, a dish, a piece of meat, a vegetable product. According to some modes of use, the microwave heating device 1 can be used to heat several portions or parts of the product 9 simultaneously. Three portions of food products are shown by way of example in Figure 1and is marked as 91. In this specification, any reference to "food 9" should be understood to also mean a product of several portions 91 to be heated simultaneously.

[0044] According to some modes of use, the food 9 to be heated may be a frozen (or deep-frozen) food, and the heating device 1 may be used to defrost this frozen food 9. According to other modes of use, the device 1 may be used to cook the food 9.

[0045] The device 1 comprises a support structure 10, wherein the support structure 10 comprises, for example, a box-like housing and / or a frame supporting other components of the device 1. The device 1 further comprises a heating chamber 12, wherein the heating chamber 12 is designed to receive at least one food 9 to be heated (specifically, a portion 91). For example, the heating chamber 12 is located within the support structure 10. The device 1 may comprise a door (not shown), wherein the door may be alternately opened and closed, when open to allow access to the heating chamber 12, and when closed to perform heating of the food 9 in the closed heating chamber 12.

[0046] The device 1 comprises a control unit 3 and a microwave generating system 20, wherein the microwave generating system 20 comprises at least two radiating sections 25. Figure 1 In the example embodiment of FIG. 4 , the microwave generating system 20 includes four radiation portions 25. In other example embodiments, the radiation portions 25 may be two, three, or more than four.

[0047] The at least two radiating portions 25 face the heating chamber 12. The microwave generating system 20 is designed to generate microwaves, and the at least two radiating portions 25 are suitable for radiating the microwaves to the heating chamber 12.

[0048] In some embodiments, microwave generation may be performed by a solid-state generator. More specifically, the microwave generation system 20 includes solid-state power amplifiers 22, each of which is connected to a corresponding radiation portion 25. The power amplifiers 22 may be controlled independently of each other, for example by the control unit 3, so that the signal generated by each of the power amplifiers 22 may be controlled in terms of frequency, phase, and amplitude. The generated signal is received by the corresponding radiation portion 25 to radiate the corresponding microwave. Therefore, the microwave radiated by the radiation portion 25 may be changed in terms of frequency, phase, and / or power.

[0049] The operating range of microwave frequency may be between 300 MHz and 300 GHz. Specifically, in some example embodiments, the operating range of microwave frequency may be between 2400 MHz and 2500 MHz. In some embodiments, the operating range of microwave phase may be between 0° and 360°. In some embodiments, the maximum value of the power provided by each power amplifier 22 may be 200 W. Obviously, in other example embodiments, smaller or larger power values ​​are possible.

[0050] In some embodiments, the microwave generating system 20 may be designed to generate corresponding microwaves having the same frequency and different phases, and radiate the corresponding microwaves via at least two radiation portions.

[0051] In an example embodiment with two radiation parts, the two radiated microwaves may have different phases from each other. Therefore, one radiation part may be regarded as a reference radiation part, and the microwaves radiated by the other radiation part may have a phase shift relative to the microwaves radiated by the reference radiation part.

[0052] In other example embodiments having more than two radiation portions, the radiated microwaves may have mutually different phases. Therefore, one radiation portion may be regarded as a reference radiation portion, and the microwaves radiated by each of the other radiation portions may have a corresponding phase shift relative to the microwaves radiated by the reference radiation portion. Figure 1 In the specific example embodiment, three phase shifts are defined.

[0053] The frequency value and phase shift value(s) identify or define an operating configuration of the microwave generating system 20. In other words, an operating configuration is a combination of frequency and phase at which the microwave generating system 20 operates. In the specific example embodiment having four radiating sections 25, each operating configuration is defined by a frequency value and three phase shift values.

[0054] In addition to the operating configuration defined by frequency and phase, the operating conditions of the microwave generating system 20 also include the power level at which the radiating portion 25 is set.

[0055] The control unit 3 may be configured to operate the microwave generating system 20 and change the frequency and phase shift of the microwaves generated by the microwave generating system 20. In other words, the control unit 3 may be configured to set a plurality of operating configurations according to which the microwave generating system 20 may operate. In addition, the control unit 3 may adjust the power level of each radiation section 25. Specifically, the radiation sections 25 may be operated at the same power level, that is, the microwaves radiated by the radiation sections 25 may all have the same power.

[0056] During use of the microwave heating device 1, radiant power is associated with the microwaves radiated by the radiating portion 25, and the radiant power is partially absorbed by the food 9 to be heated located in the heating chamber 12. The absorbed portion of the radiant power is converted into heat in the food 9, while the remaining portion of the radiant power is reflected by the heating chamber 12.

[0057] In some embodiments, the microwave heating device 1 includes a reflected power detection system, wherein the reflected power detection system is configured to detect the portion of the radiation power reflected by the heating chamber 12. More specifically, the reflected power detection system may include a plurality of detectors 27, one detector 27 for each radiation portion 25. Each detector 27 may be adapted to detect the microwave power returned from the heating chamber 12 to the corresponding radiation portion 25.

[0058] For example, each detector 27 may be a power detector positioned between the power amplifier 22 and the corresponding radiation portion 25. Furthermore, the radiation power (or forward power) may be detected or measured for each radiation portion 25. For example, the reflected power detection system and the radiation power detector may be included in the electronic circuit of the microwave heating device 1.

[0059] In some embodiments, the control unit 3 may be connected to a reflected power detection system (and also to a radiated power detector) and may be configured to calculate an energy efficiency that is inversely proportional to the ratio of reflected power to radiated power. rad ) can be calculated as the sum of the individual powers radiated by the radiating portion 25; the reflected power (P ref ) can be calculated as the sum of the individual reflected powers detected by the detector 27. The energy efficiency (Eff) can be expressed as a percentage and can be calculated as follows: Eff = (1-P ref / P rad )*100.

[0060] The control unit 3 may be configured to calculate an energy efficiency value for each operating configuration of the microwave generating system 20 .

[0061] like Figure 2 Schematically shown, a learning program 100 in which it is desired to "learn" the food 9 may be performed before a heating program 120 in which it is desired to heat and / or cook the food 9. A selection program 110 may be performed after the learning program 100 and before the heating or cooking program 120 in order to select operating conditions for the subsequent heating program 120 based on the results obtained in the learning program 100. The control unit 3 may be configured to run these programs.

[0062] According to some methods of use, the learning procedure 100 may have the basic function of evaluating how the food 9 in the heating chamber 12 interacts with the microwaves, so as to allow the parameters of the microwave generating system 20 to be advantageously set, the settings being customized for the specific food 9. In other words, the learning procedure 100 may be a check aimed at testing the food 9 and identifying the best heating conditions for the food 9 in the heating chamber 12. It should be noted that the learning procedure 100 should be performed while the food 9 to be heated is in the heating chamber 12. Therefore, the food 9 should be located in the heating chamber 12 before starting the learning procedure 100.

[0063] Basically, the learning procedure 100 may include applying microwaves to the food product 9 according to a plurality of different operating configurations by sequentially operating the radiation sections 25 at different phases and different frequencies (but simultaneously operating all radiation sections 25 at the same frequency).

[0064] During the learning procedure 100, the control unit 3 may operate the microwave generation system 20 at frequencies and phase shifts (multiple) varying within corresponding ranges, and may calculate energy efficiency for each of the corresponding operating configurations. In other words, several configurations are analyzed sequentially, and energy efficiency is calculated for each configuration.

[0065] For example, the frequency may be changed in a range between 2400 MHz and 2500 MHz in a frequency step of 10 MHz. In other embodiments, the frequency may be changed in a range between 300 MHz and 300 GHz. For each frequency, several combinations of phases may be selected by changing the phase shift in a corresponding phase range in a phase step. More specifically, the phase range is an interval between 0° and 360°, and the phase step may be constant within the interval. For example, the phase step is 45°. It should be considered that a phase shift of 0° is equivalent to a phase shift of 360°, and thus, the corresponding operating configuration should be considered only once.

[0066] The energy efficiency data obtained for the selected operating configurations can be electronically stored to allow for subsequent processing. For example, the data is stored as a data matrix, wherein the data matrix contains all selected operating configurations and corresponding energy efficiency values. For example, Figure 3 A three-dimensional space is shown where the energy efficiency is mapped in grayscale according to the three phase shifts.

[0067] Furthermore, due to the learning procedure 100, for each frequency, a graph of the trend of the energy efficiency depending on the configuration (ie depending on the phase or phase shift) can be obtained, such as Figure 5 shown. Figure 3 and Figure 5 The curve diagram is specific to the food 9 in the heating chamber 12 and also depends on the technical features of the microwave heating device 1.

[0068] Specifically, the control unit 3 can be configured to operate the microwave generation system 20 in the selected operating configurations, to calculate the energy efficiency for each of the selected operating configurations, and to save the obtained data to an electronic data storage device. In a possible method of use, the data obtained in the learning program 100 can be screened to discard any operating configuration that does not meet one or more additional requirements, so that the operating configurations of the subsequent selection program 110 can be fewer than the operating configurations of the learning program 100.

[0069] According to one method of use, the acquired data may be processed in a selection process 110 via a processing algorithm to select a plurality of operating configurations that may be used to heat food 9 .

[0070] According to one aspect of the present disclosure, the selection procedure 110 may be substantially as follows: selecting an operating frequency, selecting a reference operating configuration under the operating frequency, and selecting a plurality of operating configurations around the reference operating configuration.

[0071] In this article, we combine Figure 4 One possible processing algorithm for selecting an operating frequency is described with reference to a block diagram of FIG. 20. For each frequency in the obtained data, in operation 200, the energy efficiency data may be analyzed to single out an operating configuration with a maximum energy efficiency and an operating configuration with a minimum energy efficiency. The efficiency difference (ΔEff) may be calculated as the difference between the maximum energy efficiency (Max Efficiency) and the minimum energy efficiency (Min Efficiency) at the same frequency (see also FIG. 20). Figure 5 ). In operation 210, the operating frequency may be selected as a frequency value that minimizes the efficiency difference. Therefore, when running the algorithm, the control unit 3 is configured to select the operating frequency corresponding to the minimum difference between the maximum energy efficiency and the minimum energy efficiency (see Figure 6 ).

[0072] Other processing algorithms may be used to select the operating frequency. For example, the standard deviation of the efficiency difference at the same frequency and / or the maximum energy efficiency may be considered to define a frequency-dependent mathematical function. The operating frequency may be selected by minimizing or maximizing the mathematical function.

[0073] After the operating frequency is selected in operation 210 , a reference operating configuration may be selected as an operating configuration having the greatest energy efficiency at the selected operating frequency in operation 220 . And this selection may be made based on data obtained in the learning procedure 100 .

[0074] In operation 230, multiple operating configurations of the heating program 120 may be selected, all having the selected operating frequency, but having phase shifts selected around the corresponding phase shift of the reference operating configuration. Thus, the operating configurations selected for the heating program 120 may have the same frequency and differ from each other in at least one phase shift.

[0075] Specifically, the phase shift of each selected operating configuration may have a certain phase shift distance relative to the corresponding phase shift of the reference operating configuration, so that in the space of phase shifts, the reference operating configuration is surrounded by the selected operating configuration. Thus, the heating program 120 may follow a phase nudging method around the reference operating configuration.

[0076] In other words, the absolute value of the difference between each phase shift of any selected operating configuration and the corresponding phase shift of the reference operating configuration may be equal to a preset value, wherein the preset value is the phase shift distance.

[0077] For example, Figure 7 A microwave heating device is shown with a microwave generating system 20 comprising three radiating portions 25. Each operating configuration can therefore be defined by a frequency value and two phase shift values, calculated for example as the difference between the phase of the first and second radiating portions and the phase of the third radiating portion.

[0078] The operating configurations correspond to points in a two-dimensional space of phase shifts. The operating configurations chosen for the heating program correspond to points that can be vertices of a polygon in this two-dimensional space (labeled with reference numerals 320, 330, 340, 350), and the reference operating configuration corresponds to an interior point of the polygon (specifically, the center point, labeled with reference numeral 310). Figure 7 The reference operating configuration 310 is shown surrounded by operating configurations 320, 330, 340, 350 for the heating program 120. In a specific example, the selected operating configurations 320, 330, 340, 350 are four and may correspond to the vertices of a square, while the reference operating configuration 310 may correspond to the center of the square. The configuration having the minimum energy efficiency at the selected operating frequency is also shown and is labeled with reference number 300.

[0079] According to another example, Figure 8 A microwave heating device is shown with a microwave generating system 20 comprising four radiating sections 25. Each operating configuration can therefore be defined by a frequency value and three phase shift values, calculated, for example, as the difference between the phases of the first, second and third radiating sections and the phase of the fourth radiating section.

[0080] The operating configurations correspond to points in the three-dimensional space of phase shifts. The operating configurations selected for the heating program 120 correspond to points that can be vertices of a polyhedron in this three-dimensional space (labeled with reference numerals 420, 430, 440, 450, 460, 470, 480, 490), and the reference operating configuration corresponds to a point in the body of the polyhedron (specifically, the center point, labeled with reference numeral 410). Figure 8The reference operating configuration 410 is shown surrounded by operating configurations 420, 430, 440, 450, 460, 470, 480, 490 for the heating program 120. In a specific example, the selected operating configurations 420, 430, 440, 450, 460, 470, 480, 490 are eight and may correspond to the vertices of a cube, while the reference operating configuration 410 may correspond to the center of the cube. The configuration having the minimum energy efficiency at the selected operating frequency is also shown and is labeled with reference number 400.

[0081] This aspect can be generalized to a microwave heating apparatus having a microwave generating system 20 that includes any number N of radiating portions 25, where N is greater than or equal to 2. In this case, each operating configuration can be defined by a frequency value and N-1 phase shift values. The operating configuration corresponds to a point in the (N-1)-dimensional space of phase shifts. The operating configuration selected for the heating program 120 can correspond to a point that can be a vertex of a hyperpolyhedron in the (N-1)-dimensional space of phase shifts, and the reference operating configuration can correspond to a point in the body of the hyperpolyhedron (specifically, a center point). Specifically, the selected operating configuration can be 2 N -1 The reference operating configuration may correspond to the center of the hypercube.

[0082] According to one mode of operation configuration for selecting the heating program 120, the phase shift for each of them may be calculated as follows: phase_shift i =ref_phase_shift i ±phase_dist i ,

[0083] where phase_shift i is the i-th phase shift of the operating configuration, ref_phase_shift i is the i-th phase shift of the reference operating configuration, ref_phase_shift i is the phase shift distance chosen for the i-th phase shift. All possible combinations of phase shift values ​​may be considered to generate a set of operating configurations for the heating program 120 .

[0084] To obtain a square, cube, or hypercube, phase_dist i has the same value for all phase shifts.

[0085] In some embodiments, the control unit 3 may be configured to calculate the phase shift distance from the efficiency difference for the selected operating frequency in a manner such that the phase shift distance is inversely proportional to the efficiency difference. A smaller efficiency difference will require a larger phase shift distance and a wider phase nudge around the reference configuration, while a larger efficiency difference will require a smaller phase shift distance and a narrower phase nudge.

[0086] According to some specific algorithms, the phase shift distance (in degrees) can be calculated as the difference between 90 degrees and the efficiency difference (difference in efficiency expressed as a percentage) at the selected operating frequency: phase_dist = 90° - ΔEff.

[0087] In this paper, combined with Figure 6 and Figure 7 10. The lowest efficiency difference obtained from the learning process 100 applied to a particular product 9 or a group of product portions 91 is found at a frequency of 2470 MHz, which can be selected as the operating frequency of the heating process 120. The efficiency difference at this frequency is 18%, so the phase shift distance is: 90-18=72 degrees. For example, Figure 7 A heating device 1 with three radiating sections 25 is represented, in which two phase shifts can be defined. The maximum efficiency difference for the selected frequency of 2470 MHz is found at a phase_shift1 of 140 degrees and at a phase_shift2 of 160 degrees. These values ​​represent the reference operating configuration (ref_phase_shift1; ref_phase_shift2). Therefore, the phase_shift1 of the heating operating configuration is selected at 68 degrees (i.e. 140–72) or at 212 degrees (i.e. 140+72), and the phase_shift2 of the heating operating configuration is selected at 88 degrees (i.e. 160–72) or at 232 degrees (i.e. 160+72). Therefore, the phase shift values ​​of the operating configuration of the heating program 120 are: (68; 232), (212; 232), (212; 88), (68; 88).

[0088] After the plurality of operating configurations have been selected in the selection procedure 110, the at least two radiation sections 25 may be sequentially operated in the plurality of operating configurations during the heating procedure 120. According to some modes of use, during the heating procedure 120, each of the selected operating configurations may be active for the same amount of time, i.e., the total heating time may be equally divided between the selected operating configurations.

[0089] According to some embodiments, the control unit 3 may be configured to operate the microwave generating system 20 at an adjustable power that changes between the learning program 100 and the heating program 120. Specifically, the radiant power in the learning program 100 may be less than the radiant power in the heating program 120. In other words, during the learning program 100, the heating chamber 12 may be fed with microwaves having a very small power (e.g., a total power of 20 W), that is, the power amplifier 22 may be operated at a reduced power (e.g., 5 W per power amplifier). This may be beneficial in avoiding significant heating or cooking of the food 9 during the learning program 100. The learning program 100 may last for several seconds, which is a negligible time compared to the entire cooking time of several minutes. During the heating program 120, the heating chamber 12 may be fed with microwaves having a large power, for example, the power amplifier 22 may be operated at a power of 200 W.

[0090] In other embodiments or use modes, it is not so important to avoid significant heating or cooking during the learning procedure 100. For example, in some cases, heating during the learning procedure 100 may be beneficial to shorten the overall cooking time. Therefore, in those cases, the learning procedure 100 may be performed at the same power as in the heating procedure 120.

[0091] In some methods of use, the heating program 120 may be paused at least once to repeat the learning program 100 so that the heating program 120 can continue with the updated operating configuration. In other words, the learning program 100 and the heating program 120 are repeated multiple times for the same product 9 in the heating chamber 12, each heating program 120 being based on data obtained in the previous learning program 100 and processed in the selection program 110. This is beneficial for adapting the heating program 120 to the changing physical characteristics of the food 9 during heating or cooking.

[0092] As described above, the control unit 3 may be configured to run the learning program 100, the selection program 110, and the heating program 120. To perform these tasks, the control unit 3 may include processing circuitry 31, wherein the processing circuitry 31 may be configured to interface with, control, or otherwise coordinate the operation of the various components or modules described herein in conjunction with performing control of the various components or modules described herein as described herein. The control unit 3 may utilize the processing circuitry 31 to provide electronic control inputs to one or more functional units of the microwave generation system 20 and / or the reflected power detection system, receive, send, and / or process data associated with one or more functional units, and perform communications necessary to implement the ability to control the operation of the microwave generation system 20 and / or the reflected power detection system (or components thereof) as described herein.

[0093] In some embodiments, the processing circuit 31 may be embodied as a chip or a chipset. In other words, the processing circuit 31 may include one or more physical packages (e.g., chips) that include materials, components, and / or wires on a structural assembly (e.g., a substrate). The structural assembly may provide physical strength, size savings, and / or electrical interaction limitations to the component circuits included on the structural assembly. The processing circuit 31 may therefore be configured in some cases to implement an embodiment of the present invention on a single chip or as a single "system on a chip." Therefore, in some cases, a chip or a chipset may constitute a component for performing one or more operations for providing the functions described herein.

[0094] In an example embodiment, the processing circuit 31 may include one or more instances of a processor 312 and a memory 314 (e.g., volatile or non-volatile memory), which may communicate with or otherwise control the device interface 33 and the user interface 35. Thus, the processing circuit 31 may be embodied as a circuit chip (e.g., an integrated circuit chip) that is configured (e.g., by hardware, software, or a combination of hardware and software) to perform the operations described herein.

[0095] The device interface 33 may include one or more interface mechanisms that enable communication with other devices. In some cases, the device interface 33 may be any component configured to receive data from and / or transmit data to a device or component (e.g., a system component) that communicates with the processing circuit 31 via an internal and / or external communication mechanism, such as a device or circuit embodied in hardware or a combination of hardware and software. Thus, for example, the device interface 33 may also include a device and / or component for receiving data from the microwave generation system 20 and / or the reflected power detection system and / or one or more sensors.

[0096] The subject matter of the present disclosure may be modified and adapted in several ways without departing from the scope of the present disclosure. All details of the present invention may be replaced by other technically equivalent elements and materials used, and the shapes and sizes of the various components may be changed as required. Therefore, it is apparent that the example embodiments described above are non-limiting, and other embodiments are possible, while still being covered by the appended claims. In addition, although this specification and the accompanying drawings describe examples of combinations of elements and functions, it is apparent that embodiments with different combinations of elements and functions, which are covered by the teachings of the present disclosure in any case, are possible.

[0097] It should also be noted that the advantages and benefits described with reference to the example embodiments described above are not necessarily present in all possible embodiments covered by the teachings of the present disclosure.Specific terms used in this specification are used in a generic and descriptive sense and not for purposes of limitation.

Claims

1. A microwave heating device, comprising: - a heating chamber configured to receive a food product to be heated; - a microwave generating system configured to generate microwaves and comprising at least two radiating sections adapted to radiate microwaves into the heating chamber, the radiating power being associated with the radiated microwaves and, in use, a portion of the radiating power being reflected in the heating chamber; as well as - control unit; wherein the microwave generating system is configured to radiate corresponding microwaves having the same frequency and different phases via the at least two radiating portions, such that each set of a given frequency and a corresponding different phase represents an operating configuration, wherein the control unit is configured to identify a plurality of frequencies and generate a matrix of operating configurations and values ​​of energy efficiency for each of the operating configurations, the energy efficiency being inversely proportional to a ratio of reflected power to radiated power for each of the operating configurations, and Wherein the control unit is configured to run a selection program to determine a strategy for heating the food product based on the matrix.

2. The microwave heating device according to claim 1, wherein the selection procedure comprises determining an operating frequency, determining a reference operating configuration as an operating configuration having maximum energy efficiency at the operating frequency, and determining a plurality of selected operating configurations based on a difference metric relative to the reference operating configuration.

3. The microwave heating apparatus of claim 2, wherein the difference metric comprises a measure of a difference in phase shifts relative to the corresponding phase shifts of the reference operating configuration.

4. The microwave heating apparatus of claim 3, wherein the selected operating configuration surrounds the reference operating configuration in phase shift space.

5. The microwave heating device according to claim 2, wherein determining the operating frequency comprises determining a standard deviation between a maximum efficiency and a minimum efficiency for each frequency in the matrix, and selecting the operating frequency as a frequency value at which the standard deviation is minimized or maximized.

6. The microwave heating device according to claim 2, wherein determining the operating frequency comprises determining an efficiency difference between a maximum efficiency and a minimum efficiency for each frequency in the matrix, and selecting the operating frequency as a frequency value at which the efficiency difference is minimized.

7. The microwave heating device according to claim 2, wherein determining the operating frequency comprises determining a mathematical function based on maximum efficiency and minimum efficiency for each frequency in the matrix, and selecting the operating frequency as a frequency value at which the mathematical function is minimized or maximized.

8. The microwave heating device according to claim 2, wherein the control unit is configured to run a heating program in which the microwave generating system is operated in each of the selected operating configurations sequentially.

9. The microwave heating apparatus of claim 1, wherein the selection procedure comprises determining an operating frequency, determining a reference operating configuration as an operating configuration having maximum energy efficiency at the operating frequency, and running a phase fine-tuning procedure around the reference operating configuration.

10. The microwave heating device according to claim 9, wherein the phase fine-tuning procedure comprises determining a preset phase shift distance and changing the phase shift around the reference operating configuration by the current phase shift distance.

11. The microwave heating device according to claim 9, wherein the control unit is configured to calculate the phase shift distance according to an efficiency difference, the efficiency difference being a difference between a maximum energy efficiency and a minimum energy efficiency at the selected operating frequency, and The phase shift distance is inversely proportional to the efficiency difference.

12. The microwave heating apparatus of claim 1, further comprising a method for graphing trends of energy efficiency versus operating configurations to exclude operating configurations that do not meet predetermined requirements.

13. A method for operating a microwave heating device, the microwave heating device comprising a heating chamber and at least two radiating sections adapted to radiate microwaves into the heating chamber, wherein the at least two radiating sections are operable in a plurality of operating configurations, the plurality of operating configurations differing in frequency and / or phase shift between the radiated microwaves, the method comprising: radiating corresponding microwaves having the same frequency and different phases via the at least two radiating portions so that each set of a given frequency and corresponding different phases represents an operating configuration, Identify multiple frequencies; generating a matrix of operating configurations and values ​​of energy efficiency for each of the operating configurations, the energy efficiency being inversely proportional to a ratio of reflected power to radiated power for each of the operating configurations; as well as A selection program is run to determine a strategy for heating a food product in the heating chamber based on the matrix.

14. The method of claim 13, wherein the selection procedure comprises determining an operating frequency, determining a reference operating configuration as an operating configuration having maximum energy efficiency at the operating frequency, and determining a plurality of selected operating configurations based on a difference metric relative to the reference operating configuration.

15. The method of claim 14, wherein the difference metric comprises a measure of a difference in phase shifts relative to respective phase shifts of the reference operating configuration.

16. The method of claim 15, wherein the selected operating configuration surrounds the reference operating configuration in phase shift space. 17 . The method of claim 14 , wherein determining the operating frequency comprises determining an efficiency difference between a maximum efficiency and a minimum efficiency for each frequency in the matrix, and selecting the operating frequency as a frequency value at which the efficiency difference is minimized.

18. The method of claim 14, wherein determining the operating frequency comprises determining a mathematical function based on maximum efficiency and minimum efficiency for each frequency in the matrix, and selecting the operating frequency as a frequency value at which the mathematical function is minimized or maximized.

19. The method of claim 13, wherein the selection procedure comprises determining an operating frequency, determining a reference operating configuration as an operating configuration having maximum energy efficiency at the operating frequency, and running a phase fine-tuning procedure around the reference operating configuration.

20. The method of claim 19, wherein the phase fine-tuning procedure comprises determining a preset phase shift distance and changing the phase shift about the reference operating configuration by the current phase shift distance.

Images