Food moisture content detection system suitable for baking electric oven and cooking method

Abstract

The invention provides a food moisture content detection system suitable for a baking electric oven and a cooking method.The detection system comprises an electric oven body used for bearing food and cooking the food in the electric oven body; at least part of the microwave detection device is arranged in the electric oven body, and the microwave detection device can emit microwaves to food in the electric oven body and detect the attenuation characteristics of the microwaves penetrating through the food; the program processing module is in communication connection with the microwave detection device and used for obtaining the water content of the food according to the microwave attenuation characteristics and adjusting cooking parameters of the electric oven according to the water content. The microwave signal generating assembly and the microwave signal receiving device are arranged in the electric oven body, the microwave attenuation amount is detected to obtain the water content of food, the detection efficiency is high, the change state of the water content can be directly monitored, the current water content of the food can be obtained more accurately and timely in cooperation with fitting correction of the detection result, and the detection accuracy is improved. Therefore, the strategy is adjusted and the food cooking effect is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of electric ovens, and more particularly, to a food moisture content detection system and a cooking method applicable to a baking electric oven. Background Art

[0002] As a household cooking appliance with a high penetration rate, an electric oven is often used in various cooking processes. Although the moisture content of food itself has a significant impact on the baking effect during the use of an electric oven for baking, the exploration of existing detection methods for the moisture content of food itself in electric ovens is still in a temporarily missing state.

[0003] Affected by the working environment of the electric oven itself, the air humidity inside the oven cavity is very low during operation, and the water vapor evaporated from the food due to heating is not enough to be sensed by a traditional humidity sensor that detects humidity by detecting water vapor. Therefore, the traditional water vapor detection scheme applicable to other cooking appliances is difficult to play a role in detecting the moisture content of solid food in an electric oven.

[0004] Chinese Patent CN201610370828.5 discloses an oven, including a chamber for baking work, and further including electrodes arranged in the chamber to form a circuit and a detection device for detecting the resistance between the electrodes. By increasing the electrodes and detecting the resistance value between the electrodes, the water content in the air between the electrodes can be judged, so as to obtain the humidity situation in the oven cavity. This patent uses electrodes instead of humidity sensors to avoid the problem of low temperature resistance of humidity sensors, and is applicable to ovens with higher baking temperatures to ensure the stability of the baking effect. However, due to the very low air humidity in the electric oven cavity, it is also difficult to detect the humidity change inside the cavity using electrodes, and it is even more impossible to infer the moisture content inside the food, affecting the stability of the food baking effect. Summary of the Invention

[0005] The present invention aims to propose a food moisture content detection system and a cooking method applicable to a baking electric oven to solve the problem that the air humidity inside the electric oven cavity is very low in the prior art, and it is impossible to accurately detect the moisture content in solid food by detecting humidity.

[0006] To solve the above problems, the technical solution of the present invention is achieved as follows:

[0007] A food moisture content detection system applicable to a baking electric oven, comprising:

[0008] Comprising:

[0009] An electric oven body for carrying food and capable of cooking the food therein;

[0010] A microwave detection device, which is at least partially disposed in the electric oven box and is capable of emitting microwaves to food in the electric oven box and detecting microwave attenuation characteristics after passing through the food;

[0011] A program processing module is communicatively connected with the microwave detection device and is used to obtain the moisture content of the food according to the microwave attenuation characteristics and adjust the cooking parameters of the electric oven according to the moisture content.

[0012] A microwave detection device is set up using the principle that microwaves will have corresponding attenuation when passing through an object. The microwave detection device can emit microwaves to food and receive microwaves on the other side of the food. There will be corresponding attenuation in the process of microwaves passing through food, so that the microwave power has corresponding changes. The microwave detection device can detect the microwave attenuation characteristics after the microwaves pass through the food. The microwave attenuation characteristics include microwave attenuation amount and / or microwave power attenuation amount and / or microwave voltage attenuation amount, etc. The program processing module can obtain the moisture content of the food according to the microwave attenuation characteristics, and obtain a corresponding curve between the microwave attenuation value and the moisture content of the food, and then the cooking parameters of the food such as the remaining cooking time can be adjusted according to the corresponding curve, thereby effectively solving the pain point of the prior art that the moisture content of the heated food in the electric oven cannot be detected, and improving the cooking effect of the electric oven and the user experience.

[0013] Furthermore, the microwave detection device comprises:

[0014] A microwave signal generating component is arranged on one of the inner walls of the electric oven box and is used to emit microwave signals in the direction where the food is located;

[0015] A microwave signal receiving device is arranged on another inner wall of the electric oven body opposite to the microwave signal generating assembly, and is used to receive the microwave signal emitted by the microwave signal generating assembly after passing through the food, and send it to the detector;

[0016] A detector, the detector is connected to the microwave signal receiving device for receiving the microwave signal sent by the microwave signal receiving device and converting the microwave signal into a voltage signal;

[0017] The signal receiving and processing module is connected to the detector for communication, and is used for receiving the voltage signal sent by the detector, performing analog-to-digital conversion on the voltage signal after processing, and transmitting the converted signal to the program processing module.

[0018] The microwave signal generating component emits microwave signals of a specified frequency in the direction of the food. After the microwaves pass through the food, they are received by the microwave signal receiving device. The microwave signal receiving device transmits the received microwave signals to a detector. The detector processes the microwave signals and converts the difficult-to-understand microwave signals into easily readable voltage signals. The signal receiving and processing module receives the output DC signals from the detector, performs arithmetic amplification and filtering processing, and then transmits them to an AD converter for analog-to-digital conversion to convert the analog signals into digital signals, thereby obtaining effective AD values, which are convenient for obtaining the subsequent moisture content.

[0019] Further, the microwave signal generating component includes a microwave transmitting antenna and a microwave signal generator. The microwave signal receiving device includes a microwave receiving antenna. The microwave signal generator is used to output microwave signals. The microwave transmitting antenna is used to effectively radiate the microwave signals so that they can penetrate the food to be detected. The microwave receiving antenna is used to capture the microwave signals that penetrate the food to be detected.

[0020] The moisture content in the food can be effectively detected through the attenuation of the microwaves, thereby providing more accurate reference data for food cooking and helping to improve the cooking effect.

[0021] Further, a temperature measuring device is provided in the electric oven cabinet. The temperature measuring device is used to detect the temperature of the food in the electric oven cabinet in real time. The temperature measuring device is communicatively connected to the program processing module. The program processing module adjusts the cooking parameters according to the moisture content and temperature of the food in the electric oven cabinet.

[0022] The cooking effect of the food is closely related to characteristic indexes such as its moisture content and temperature. By detecting the food temperature and coordinating it with the moisture content to adjust the cooking parameters, a better cooking effect can be obtained.

[0023] The present invention also discloses a cooking method applicable to a baking electric oven. The electric oven includes the moisture content detection system as described above. The cooking method includes:

[0024] Step S1: Start the electric oven and determine whether the menu type has been set. If not, execute Step S2; if so, execute Step S3:

[0025] Step S2: Pop up a menu setting window and wait for the menu to be set, then execute Step S3:

[0026] Step S3: Start the moisture content detection system to detect the moisture content of the food and obtain the current moisture content of the food;

[0027] Step S4: Determine whether the moisture content of the food is within the preset range. If not, execute Step S5; if so, execute Step S6;

[0028] Step S5: Continue baking and continuously detect the moisture content of the food until the moisture content of the food reaches the maximum value within the preset range, then execute Step S6;

[0029] Step S6: Adjust the remaining cooking time t of the food according to the moisture content of the food;

[0030] Step S7: Determine whether the remaining cooking time t of the food is 0. If not, continue to detect the moisture content of the food and return to execute Step S4; if yes, execute Step S8;

[0031] Step S8: The cooking ends.

[0032] By detecting the moisture content of the food through the microwave attenuation amount passing through the food, it is not affected by the extremely low water content in the air in the oven, and can detect the moisture content in the food more accurately, solving the pain point that the moisture content of the heated food cannot be detected in the electric oven, and improving the cooking effect of the electric oven and the user experience.

[0033] Further, a temperature measuring device is provided in the electric oven cavity. The temperature measuring device can detect the real-time temperature of the food during cooking. Step S3 further includes: starting the temperature measuring device to detect the real-time temperature of the food; Step S6 includes: adjusting the remaining cooking time t of the food according to the moisture content and temperature of the food.

[0034] Through the setting of the moisture content detection system and the temperature measuring device, it is possible to dynamically detect the dynamic characteristic indexes such as the moisture content and temperature of the current food during cooking, so as to be able to adjust the cooking parameters of the food in real time, and thus obtain a better cooking effect.

[0035] Further, the current moisture content obtained in Step S3 is the moisture content value corrected by the correction curve model, and the correction curve model is obtained by fitting the theoretical attenuation curve of the food microwave attenuation amount and the moisture content with the measured attenuation curve.

[0036] During the actual measurement process, due to problems such as microwave scattering and food non-uniformity, the microwave energy will be lost during the transmission process, so that the measured microwave attenuation value may be higher than the attenuation value actually passing through the food. Therefore, by fitting the theoretical attenuation curve calculated by the microwave transmission method with the measured attenuation curve obtained during the actual detection process, it is possible to measure the moisture content of the food within an acceptable error range.

[0037] Further, the theoretical attenuation curve is obtained through Equation (9):

[0038] (9)

[0039] Wherein, A is the energy attenuation, with the unit of dB, d is the thickness of the food material, with the unit of mm, and a is the attenuation constant, which is obtained through Equation (2) or (3).

[0040] (2)

[0041] Wherein, λ is the microwave wavelength, and ε is the dielectric property of the food to be measured. is the tangent value of the phase angle of the complex dielectric constant;

[0042] (3).

[0043] Through the above settings, using the principle of the microwave transmission method, the mathematical relationship between the moisture content of different foods, the energy attenuation of the microwave signal, and the phase shift is deduced, so as to obtain the theoretical attenuation curve of the estimated microwave attenuation and the moisture content of the food material.

[0044] Further, the method for obtaining the measured attenuation curve includes:

[0045] Step ST1: Divide the same kind of food material into several groups according to the moisture content, with two portions in each group. The weight, size, and moisture content of the two portions of food material in the same group are the same, and the moisture content of the food material in different groups is different.

[0046] Step ST2: For the two portions of food material in the same group, one portion is completely dried by the drying method to obtain its moisture content data, and the other portion is dried by the microwave transmission method to obtain its microwave attenuation data; repeat the above operations until all the food materials in all groups are processed.

[0047] Step ST3: Fit the moisture content data and the microwave attenuation data in Step ST2 to obtain the measured attenuation curve.

[0048] Step ST4: Repeat Steps ST1 to ST3 for different food materials to obtain the measured attenuation curves corresponding to different food materials.

[0049] In the design stage of the electric oven, the theoretical attenuation curve and the measured attenuation curve can be detected and fitted for common different food materials, so as to obtain the correction curve model corresponding to different food materials. When using the product subsequently, the initial detection and calculation results of the moisture content detection system are corrected by using the corresponding correction curve model for different food materials, so as to obtain more accurate moisture content data, providing a good basis for the precise cooking of food.

[0050] Further, the microwave attenuation data in Step ST3 includes the microwave attenuation amount, and the microwave attenuation amount is obtained through Equation (8):

[0051] (8)

[0052] Among them, A represents the microwave attenuation, and P in represents the input power before the microwave penetrates the food, and P out represents the output power after the microwave penetrates the food, and U in represents the input voltage before the microwave penetrates the food, and P out represents the output voltage after the microwave penetrates the food.

[0053] Through the above settings, the measured value of the microwave attenuation can be obtained, and the measured attenuation curve can be obtained by fitting it with the moisture content data obtained in step ST2.

[0054] Further, after step S3 and before step S4, it further includes:

[0055] Step S30: Determine whether at least one of the acquisition interval of the food moisture content and the acquisition interval of the food temperature in step S3 is less than the first preset time interval. If yes, execute step S4; if not, execute step S31;

[0056] Step S31: When the acquisition interval of the food moisture content is greater than or equal to the first preset time interval, perform a self-check on the state of the microwave sensor in the moisture content detection system; when the acquisition interval of the food temperature is greater than or equal to the first preset time interval, perform a self-check on the temperature sensor in the temperature measurement device;

[0057] Step S32: Give an alarm and report an error according to the self-check result, and then execute step S8.

[0058] Through the above settings, the state of the sensor can be monitored at any time. When it is found that the sensor is abnormal, cooking can be interrupted / ended in time, effectively eliminating potential safety hazards.

[0059] Compared with the prior art, the food moisture content detection system and cooking method for a baking electric oven described in the present invention have the following advantages:

[0060] By setting a microwave signal generating component and a microwave signal receiving device in the electric oven cavity, detecting the microwave attenuation to obtain the water content of the food, the detection efficiency is high, and the change state of the water content can be directly monitored. Together with the fitting correction of the detection results, the current water content of the food can be obtained more accurately and timely, so as to adjust the strategy and ensure the cooking effect of the food. The detection system provided by the present invention has a simple principle, fast and accurate detection, and significantly improves the cooking effect of the food in the electric oven. Brief Description of the Drawings

[0061] Figure 1 It is a schematic structural diagram of a microwave signal generating component and a microwave signal receiving device arranged in the electric oven cavity in the embodiment of the present invention;

[0062] Figure 2Schematic diagram of the microwave transmission detection principle described in the embodiments of the present invention;

[0063] Figure 3 Schematic diagram of the AD value processing flow described in the embodiments of the present invention;

[0064] Figure 4 Schematic diagram of the cooking method using the corresponding moisture content detection system described in the embodiments of the present invention;

[0065] Figure 5 Schematic diagram of the PID calculation process of the cooking time described in the embodiments of the present invention;

[0066] Figure 6 Schematic diagram of the moisture content curve correction described in the embodiments of the present invention. Detailed implementation manners

[0067] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are some but not all of the embodiments of the present invention. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0068] The following specifically describes a food moisture content detection system and a cooking method applicable to a baking electric oven according to an embodiment of the present invention with reference to the accompanying drawings.

[0069] Embodiment 1

[0070] This embodiment provides a food moisture content detection system applicable to a baking electric oven, as Figures 1-6 shown, for detecting the moisture content of food in the electric oven, including:

[0071] An electric oven box body for carrying food and capable of cooking the food therein;

[0072] A microwave detection device, at least part of which is arranged in the electric oven box body, capable of emitting microwaves to the food in the electric oven box body and detecting the microwave attenuation characteristics after passing through the food;

[0073] A program processing module, communicatively connected to the microwave detection device, for obtaining the moisture content of the food according to the microwave attenuation characteristics and adjusting the cooking parameters of the electric oven according to the moisture content.

[0074] In the prior art, due to the influence of the working environment of the electric oven itself, the humidity during its working process is very low, and the moisture content of the food cannot be known by humidity detection. In this embodiment, a microwave detection device is set up based on the principle that microwaves will have corresponding attenuation when passing through an object. The microwave detection device can emit microwaves to the food and receive the microwaves on the other side of the food. There will be corresponding attenuation in the process of microwaves passing through the food, so that the microwave power has corresponding changes. The microwave detection device can detect the microwave attenuation characteristics after the microwaves pass through the food. The microwave attenuation characteristics include microwave attenuation and / or microwave power attenuation and / or microwave voltage attenuation, etc. The program processing module can obtain the moisture content of the food according to the microwave attenuation characteristics, and obtain the corresponding curve of the microwave attenuation value and moisture content of the food, and then adjust the cooking parameters of the food such as the remaining cooking time according to the corresponding curve, thereby effectively solving the pain point that the moisture content of the heated food in the electric oven in the prior art cannot be detected, and improving the cooking effect of the electric oven and the user experience.

[0075] As one of the optional examples, the microwave detection device includes:

[0076] A microwave signal generating component is arranged on one of the inner walls of the electric oven box and is used to emit microwave signals in the direction where the food is located;

[0077] A microwave signal receiving device is arranged on another inner wall of the electric oven body opposite to the microwave signal generating assembly, and is used to receive the microwave signal emitted by the microwave signal generating assembly after passing through the food, and send it to the detector;

[0078] A detector, the detector is connected to the microwave signal receiving device for receiving the microwave signal sent by the microwave signal receiving device and converting the microwave signal into a voltage signal;

[0079] The signal receiving and processing module is connected to the detector for communication, and is used for receiving the voltage signal sent by the detector, performing analog-to-digital conversion on the voltage signal after processing, and transmitting the converted signal to the program processing module.

[0080] Specifically, the microwave signal generating component emits a microwave signal of a specified frequency toward the food. After the microwave passes through the food, it is received by the microwave signal receiving device. The microwave signal receiving device transmits the received microwave signal to the detector. The detector processes the microwave signal and converts the difficult-to-understand microwave signal into an easy-to-read voltage signal. The signal receiving and processing module receives the output DC signal from the detector, performs operational amplification and filtering, and then transmits it to the AD converter for analog-to-digital conversion, converting the analog signal into a digital signal, thereby obtaining a valid AD value, which is convenient for the subsequent calculation of the moisture content. It should be noted that the specified frequency is a preset frequency and is not specifically limited here.

[0081] Among them, the AD value program processing part in the signal receiving and processing module includes: for each time the program enters the interrupt to enter the AD conversion and check the conversion flag bit, and then amplify the AD value by C times and sum and take the average value N times to obtain the effective AD value after one processing. After the AD value is calibrated, its magnitude will reflect the magnitude of the microwave amplitude detected by the microwave sensor, which is convenient for subsequent calculation of the moisture content. When the sum has not reached N times, the program returns to perform AD conversion, amplification, and summation operations until the sum reaches N times. C and N are preset values and will not be further limited here.

[0082] As an example of the present invention, as Figure 1 shown, the microwave signal generating component includes a microwave transmitting antenna and a microwave signal generator, the microwave signal receiving device includes a microwave receiving antenna, the microwave signal generator is used to output microwave signals, the microwave transmitting antenna is used to effectively radiate the microwave signals so that they can penetrate the food to be detected, and the microwave receiving antenna is used to capture the microwave signals that penetrate the food to be detected. It should be understood that when the microwave signal penetrates the food, the moisture in the food will absorb and attenuate the microwave signal. Through the attenuation of the microwave, the moisture content in the food can be effectively detected, thereby providing more accurate reference data for food cooking and helping to improve the cooking effect.

[0083] The principle of microwave transmission detection is as Figure 2 shown. When the incident microwave signal is incident on the food, a part of the microwave signal is reflected by the food surface to form a reflected microwave signal. By using the comparison relationship between the incident wave signal, the reflected signal, and the transmitted wave signal, the energy attenuation of the microwave signal absorbed by the food sample to be measured can be calculated. When the moisture content of the food sample to be measured is different, the energy attenuation and phase shift of the obtained microwave signal will change. According to this relationship, the moisture content of the food can be detected quickly and accurately.

[0084] Using the microwave transmission method to measure the moisture content of food is essentially to regard the whole item to be measured as a certain dielectric in a certain microwave frequency band, and its electrical characteristics can be represented by a complex dielectric constant, as shown in Equation (1):

[0085] (1)

[0086] Among them, represents the complex form of the complex dielectric constant, represents the real part of the complex dielectric constant, represents the imaginary part of the complex dielectric constant, represents the loss angle.

[0087] In the microwave frequency band, the dielectric constant of water is 30 - 80, and the loss angle is 0.15 - 1.2. Most solid foods have a relatively small dielectric constant. The dielectric constants and loss angles of solid foods and water differ significantly. Therefore, in a solid water-containing food, a small change in its moisture content will result in a relatively large change in the dielectric constant and loss angle. So when microwave energy penetrates the solid food to be measured, different moisture contents of the solid food will lead to changes in the dielectric constant and loss angle, thereby producing different attenuation effects. This characteristic can be expressed by Equation (2):

[0088] (2)

[0089] In Equation (2), a represents the attenuation constant, λ represents the microwave wavelength, ε represents the dielectric property of the food to be measured, represents the tangent value of the composite dielectric constant phase angle. Equation (2) can be further simplified to Equation (3):

[0090] (3)

[0091] From the above inference, it can be seen that the attenuation energy of microwaves is proportional to the moisture content in the food sample to be measured. And there is a certain functional relationship between the moisture content in the food sample to be measured and the attenuation constant a. When electromagnetic waves penetrate a lossy medium with a thickness of d, the microwave attenuation A is as shown in Equation (4):

[0092] (4)

[0093] The attenuation of the microwave amplitude means energy loss. The energy loss of the microwave before and after passing through the transmission medium can be expressed by Equation (5):

[0094] (5)

[0095] Among them, P in represents the input power of the microwave before transmitting through the food, P out represents the output power of the microwave after transmitting through the food, a represents the attenuation constant, and d represents the thickness of the medium. In this example, the medium or lossy medium is the food to be detected.

[0096] According to the above formula, by measuring the microwave transmission power and the microwave reception power, the measured value of the microwave attenuation can be obtained. By combining Equation (5) and Equation (4), the relationship between the microwave attenuation and the dielectric constant can be obtained as shown in Equation (6). Based on Equation (6), the theoretical calculation of the microwave attenuation curve can be carried out:

[0097] (6)

[0098] In Equation (6), the functional relationship between the microwave attenuation A and the attenuation constant a can be obtained. By combining Equation (6) with Equation (2) or (3), the relationship between the microwave attenuation A and the dielectric constant can be obtained, thereby enabling the acquisition of the theoretical relationship curve between the microwave attenuation and the moisture content, as Figure 6 shown by the red curve T in

[0099] In this example, the detector can convert the change in microwave power into a change in voltage. To simplify the scheme for measuring the moisture content of food using microwaves, in actual detection, it is only necessary to reflect the microwave attenuation in the form of a voltage difference.

[0100] For the measurement of microwave attenuation, the microwave energy is converted into voltage for ease of calculation and experimental observation. Assume the relationship between microwave power and voltage is as Equation (7):

[0101] (7)

[0102] In Equation (7), P represents the microwave power, U represents the voltage, and Z represents the impedance during the transmission process. In practical applications, the impedance is a constant value. According to Equation (7), the microwave attenuation formula can be further simplified as:

[0103] (8)

[0104] where U in represents the input voltage before the microwave penetrates the food, and U out represents the output voltage after the microwave penetrates the food. According to Equation (8), the microwave attenuation can be obtained by measuring the voltage values before and after the microwave penetrates the solid food. By combining with the actual detection of the moisture content, the corresponding curve of the measured moisture content - microwave attenuation can be obtained, as Figure 6 shown by the blue curve M in

[0105] In this example, although the microwave attenuation after passing through the food in the electric oven cavity can be calculated by Equation (8), considering that the microwave emitted from the microwave transmitter will have a certain degree of loss due to diffraction, scattering, and fluctuations, etc., the microwave attenuation obtained by using the microwave transmission method will be higher than the actual attenuation of the microwave passing through the food. Therefore, there will be a certain degree of deviation between the food moisture content obtained in this way and the actual moisture content in general.

[0106] In this case, the program processing module includes a moisture content acquisition module. A correction curve model of the microwave attenuation of food and the moisture content is pre-stored in the moisture content acquisition module, which can obtain the moisture content of food through the microwave attenuation of food detected during the cooking process. Among them, the correction curve model is obtained by fitting the theoretical attenuation curve and the measured attenuation curve of the microwave attenuation of food and the moisture content. Among them, the theoretical attenuation curve can be obtained through Equation (6), and the measured attenuation curve can be obtained through Equation (8) and the actual detection of the moisture content. It should be understood that during the actual measurement process, due to problems such as microwave scattering and uneven food, the microwave energy will be lost during the transmission process, so that the measured microwave attenuation value may be higher than the attenuation value actually passing through the food. Therefore, by fitting the theoretical attenuation curve calculated by the microwave transmission method and the measured attenuation curve obtained during the actual detection process, the moisture content of food can be measured within an acceptable error range. It should be noted that the specific fitting method of the theoretical attenuation curve and the measured attenuation curve can refer to the prior art, such as modeling the deviation between the two curves as a compensation function, or designing a corresponding software algorithm (such as the error feedback in PID control), so that the corrected curve approaches the actual value, etc., which will not be limited here.

[0107] As another example of the present invention, a temperature measuring device is provided in the electric oven cabinet. The temperature measuring device is used to detect the temperature of the food in the electric oven cabinet in real time. The temperature measuring device is communicatively connected to the program processing module, and the program processing module adjusts the cooking parameters according to the moisture content and temperature of the food in the electric oven cabinet. It should be understood that the cooking effect of food is closely related to characteristic indicators such as its moisture content and temperature. By detecting the food temperature and adjusting the cooking parameters in combination with the moisture content, a better cooking effect can be obtained. As an optional example, the cooking parameters include but are not limited to the cooking time t. Preferably, the temperature measuring device is an infrared temperature sensor.

[0108] Embodiment 2

[0109] This embodiment provides a cooking method applicable to a baking electric oven, and the electric oven includes the moisture content detection system described in Embodiment 1.

[0110] The cooking method includes:

[0111] Step S1: Start the electric oven, and determine whether the menu type has been set. If not, execute Step S2; if so, execute Step S3:

[0112] Step S2: Pop up a menu setting window, and wait for the menu to be set, then execute Step S3:

[0113] Step S3: Start the moisture content detection system, detect the moisture content of the food, and obtain the current moisture content of the food;

[0114] Step S4: Determine whether the moisture content of the food is within a preset range. If not, execute Step S5; if so, execute Step S6;

[0115] Step S5: Continue baking and continuously detect the moisture content of the food until the moisture content of the food reaches the maximum value of the preset range, then execute Step S6;

[0116] Step S6: Adjust the remaining cooking time t of the food according to the moisture content of the food;

[0117] Step S7: Determine whether the remaining cooking time t of the food is 0. If not, continue to detect the moisture content of the food and return to execute Step S4; if so, execute Step S8;

[0118] Step S8: The cooking ends.

[0119] In this example, the moisture content of the food is detected by the microwave attenuation amount passing through the food, which is not affected by the extremely low water content in the air in the oven, and can accurately detect the moisture content in the food, solving the pain point that the moisture content of the heated food cannot be detected in the electric oven, and improving the cooking effect of the electric oven and the user experience. Specifically, in this example, the user can manually set the types of barbecue menus, and the control system of the electric oven will match the corresponding target parameters (such as the moisture content of the food, the food temperature, etc.) according to the menu set by the user. These target parameters correspond to the best cooking effect of the food; the control system of the electric oven can also obtain the preset range of the moisture content according to the set menu, so as to facilitate subsequent adjustment of the cooking time according to the moisture content. Among them, the preset range has been pre-stored in the control system during the production of the electric oven, and the producer can pre-set the corresponding preset range according to the specific types of food materials and menu types, and read and use it during the cooking process. It should be understood that the moisture content of food raw materials usually also has certain differences. Adjusting the cooking time according to the moisture content and / or temperature within the preset range can ensure the final cooking effect. When the moisture content of the food ingredients is too high, directly adjusting the cooking time may affect the final cooking effect of the food. Through the setting of Step S5, after its moisture content drops, corresponding adjustments are made, which is convenient for obtaining the best cooking effect. According to S6, the best remaining cooking time of the food can be obtained. During the cooking process of the food, the best cooking time will gradually decrease to 0. At this time, the control system will end the cooking and the food cooking is completed. It should be noted that in Step S6, adjusting the remaining cooking time t of the food according to the moisture content of the food is usually obtained by the cooking time PID algorithm program t = G(W) pre-stored in the control system, where W is the moisture content of the food. The specific algorithm program can refer to the prior art and will not be limited here. It should be noted that

[0120] As one of the preferred examples, a temperature measuring device is provided inside the electric oven cabinet. The temperature measuring device can detect the real-time temperature of the food during the cooking process. In this case, step S3 further includes:

[0121] The temperature measuring device is activated to detect the real-time temperature of the food;

[0122] Step S6 includes: adjusting the remaining cooking time t of the food according to the moisture content and temperature of the food.

[0123] By setting the moisture content detection system and the temperature measuring device, the dynamic characteristic indexes such as the current moisture content and temperature of the food can be dynamically detected during the cooking process, so that the cooking parameters of the food can be adjusted in real time, thereby obtaining a better cooking effect. It should be noted that adjusting the remaining cooking time t of the food according to the moisture content and temperature of the food is usually obtained through the cooking time PID algorithm program t = G(W, K) pre-stored in the control system, where W is the moisture content of the food and K is the food temperature. The specific algorithm program can refer to the prior art and will not be limited here.

[0124] As one of the preferred embodiments, as Figure 5 shown, the current moisture content obtained in step S3 is the moisture content value corrected by the correction curve model. The correction curve model is obtained by fitting the theoretical attenuation curve of the microwave attenuation of the food and the moisture content with the measured attenuation curve. It should be understood that during the actual measurement process, due to problems such as microwave scattering and food non-uniformity, the microwave energy will be lost during the transmission process, so that the measured microwave attenuation value may be higher than the actual attenuation value passing through the food. Therefore, fitting the theoretical attenuation curve calculated by the microwave transmission method with the measured attenuation curve obtained during the actual detection process can measure the moisture content of the food within an acceptable error range. Specifically, at the beginning of cooking, with the menu setting, the control system automatically obtains the moisture content of the food in the best cooking state, transports the moisture content to the moisture content PID algorithm program and sets it as the target food moisture content. During the cooking process, the moisture content of the food is detected and corrected, and the corrected moisture content is transported to the moisture content PID algorithm program to determine the remaining cooking time of the food. Preferably, the food temperature is also detected in real time during the cooking process, the power of the electric oven barbecue tube is adjusted according to the food temperature, and the remaining cooking time of the food is estimated according to the moisture content and food temperature to obtain a better cooking effect.

[0125] As one of the examples, the theoretical attenuation curve is obtained by formula (9):

[0126] (9)

[0127] Wherein, A is the energy attenuation amount, with the unit of dB, d is the thickness of the food material, with the unit of mm, and a is the attenuation constant, which is obtained through Equation (2) or (3).

[0128] (2)

[0129] Wherein, λ is the microwave wavelength, and ε is the dielectric property of the food to be measured. is the tangent value of the phase angle of the complex dielectric constant;

[0130] (3).

[0131] Through the above settings, using the principle of the microwave transmission method, the mathematical relationship between the moisture content of different foods and the energy attenuation and phase shift of the microwave signal is deduced, so as to obtain the theoretical attenuation curve of the microwave attenuation amount and the moisture content of the food material. Specifically, in this example, the theoretical attenuation curve of the microwave attenuation amount and the moisture content can be obtained through Equation (9). This curve represents the corresponding relationship between the microwave attenuation amount and the moisture content without considering interference such as reflection and refraction, as Figure 6 shown by curve T in. It should be understood that in specific operations, the theoretical attenuation curves can be measured and obtained for various different food materials to match the measured attenuation curves corresponding to the food materials for fitting.

[0132] As one of the optional examples, the method for obtaining the measured attenuation curve includes:

[0133] Step ST1: Divide the same kind of food material into several groups according to the moisture content, with two portions in each group. The two food materials in the same group have the same weight, size, and moisture content, and the moisture content of the food materials in different groups is different.

[0134] Step ST2: For the two food materials in the same group, one is completely dried by the drying method to obtain its moisture content data, and the other is dried by the microwave transmission method to obtain its microwave attenuation data; repeat the above operations until all the food materials in all groups are processed.

[0135] Step ST3: Fit the moisture content data and the microwave attenuation data in Step ST2 to obtain the measured attenuation curve.

[0136] Step ST4: Repeat Steps ST1 to ST3 for different food materials to obtain the measured attenuation curves corresponding to different food materials.

[0137] It should be understood that during the design stage of the electric oven, the detection and fitting of the theoretical attenuation curve and the measured attenuation curve can be carried out for common different food materials, so as to obtain the correction curve model corresponding to different food materials. When the product is used subsequently, the initial detection and calculation results of the moisture content detection system are corrected by using the corresponding correction curve model for different food materials, so as to obtain more accurate moisture content data, providing a good basis for the precise cooking of food. As an optional example, the theoretical moisture content corresponding to the same microwave attenuation amount can be compared with the measured moisture content, so as to obtain the correction parameter corresponding to the current food material, and this correction parameter can be used as the processing basis for the moisture content correction software in the moisture content detection system.

[0138] Specifically, the microwave attenuation data in step ST3 includes the microwave attenuation amount, and the microwave attenuation amount is obtained by formula (8):

[0139] (8)

[0140] Wherein, A represents the microwave attenuation amount, P in represents the input power before the microwave penetrates the food, P out represents the output power after the microwave penetrates the food, U in represents the input voltage before the microwave penetrates the food, P out represents the output voltage after the microwave penetrates the food. Through the above settings, the measured value of the microwave attenuation amount can be obtained, and it can be fitted with the moisture content data obtained in step ST2 to obtain the measured attenuation curve.

[0141] As an optional example, after step S3 and before step S4, it further includes:

[0142] Step S30: Determine whether at least one of the acquisition interval of the food moisture content and the acquisition interval of the food temperature in step S3 is less than the first preset time interval. If yes, execute step S4; if no, execute step S31;

[0143] Step S31: When the acquisition interval of the food moisture content is greater than or equal to the first preset time interval, perform a self-check on the status of the microwave sensor in the moisture content detection system; when the acquisition interval of the food temperature is greater than or equal to the first preset time interval, perform a self-check on the temperature sensor in the temperature measurement device;

[0144] Step S32: Give an alarm and report an error according to the self-check result, and then execute step S8.

[0145] It should be noted that the self-check in step S31 usually checks whether the sensor is in an open or short-circuit state, and then sets corresponding error warning codes according to the corresponding self-check states. For example, the open-circuit warning code is preset as E-01, the short-circuit warning code is set as E-02, and the others are set as E-03, etc. It should be understood that the moisture content of the food and the food temperature detected by the microwave sensor and the temperature sensor in the electric oven are extremely important for determining the remaining cooking time. When at least one of them fails, it is easy to cause an unreasonable adjustment of the remaining cooking time of the food, and in severe cases, it may affect the use safety of the electric oven. Through the above settings, the status of the sensor can be monitored at any time. When it is found that the sensor is abnormal, cooking can be interrupted / ended in time, effectively eliminating potential safety hazards. In addition, to ensure that the user can manually operate the electric oven after the electric oven gives an alarm, step S32 can also be: give an alarm error according to the self-check result. When the alarm result is a microwave sensor failure, display a manual operation interface for the user to determine whether to continue cooking or end cooking manually. Among them, the manual operation includes setting the cooking temperature and the remaining cooking time. Through the above settings, when the temperature sensor is working normally, the user can manually operate to continue cooking, improving the user experience.

[0146] As one optional example, the first preset time interval is 8 to 12 seconds, preferably 10 seconds. Through the above settings, the working status of the sensor can be determined in real time, eliminating potential safety hazards caused by sensor failures.

[0147] It should be noted that all terms for directional and positional indication in the present invention, such as: "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside", "top", "bottom", "tail end", "head end", "center", etc., are only used to explain the relative positional relationship and connection situation between components in a specific state, only for the convenience of describing the present invention, rather than requiring the present invention to be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention. In addition, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes, and should not be construed as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features.

[0148] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A food moisture content detection system applicable to a baking electric oven, characterized in that, include: The electric oven box is used to carry food and cook the food therein; A microwave detection device, which is at least partially disposed in the electric oven box and is capable of emitting microwaves to food in the electric oven box and detecting microwave attenuation characteristics after passing through the food; A program processing module is communicatively connected with the microwave detection device and is used to obtain the moisture content of the food according to the microwave attenuation characteristics and adjust the cooking parameters of the electric oven according to the moisture content.

2. The food moisture content detection system applicable to a baking electric oven according to claim 1, wherein The microwave detection device comprises: A microwave signal generating component is arranged on one of the inner walls of the electric oven box and is used to emit microwave signals in the direction where the food is located; A microwave signal receiving device is arranged on another inner wall of the electric oven body opposite to the microwave signal generating assembly, and is used to receive the microwave signal emitted by the microwave signal generating assembly after passing through the food, and send it to the detector; A detector, the detector is connected to the microwave signal receiving device for receiving the microwave signal sent by the microwave signal receiving device and converting the microwave signal into a voltage signal; The signal receiving and processing module is connected to the detector for communication, and is used for receiving the voltage signal sent by the detector, performing analog-to-digital conversion on the voltage signal after processing, and transmitting the converted signal to the program processing module.

3. The food moisture content detection system for a baking electric oven according to claim 2, characterized in that, The microwave signal generating component includes a microwave transmitting antenna and a microwave signal generator, and the microwave signal receiving device includes a microwave receiving antenna. The microwave signal generator is used to output microwave signals, the microwave transmitting antenna is used to effectively radiate microwave signals so that they can penetrate the food being detected, and the microwave receiving antenna is used to capture the microwave signals that penetrate the food being detected.

4. A food moisture content detection system applicable to a baking electric oven according to any one of claims 1-3, characterized in that, A temperature measuring device is provided in the electric oven box, and the temperature measuring device is used to detect the temperature of food in the electric oven box in real time. The temperature measuring device is communicated with a program processing module, and the program processing module adjusts cooking parameters according to the moisture content and temperature of the food in the electric oven box.

5. A cooking method applicable to a baking electric oven, characterized in that, The electric oven comprises a moisture content detection system as described in any one of claims 1 to 4, and the cooking method comprises: Step S1: Start the electric oven and determine whether the menu type has been set. If not, proceed to step S2; if yes, proceed to step S3: Step S2: Pop up the menu setting window, wait for the menu to be set, and then execute step S3: Step S3: the moisture content detection system is started to detect the moisture content of the food to obtain the current moisture content of the food; Step S4: Determine whether the moisture content of the food is within a preset range. If not, proceed to step S5; if yes, proceed to step S6; Step S5: Continue baking and continue to detect the moisture content of the food until the moisture content of the food reaches a maximum value within a preset range, and then execute step S6; Step S6: adjusting the remaining cooking time t of the food according to the moisture content of the food; Step S7: determine whether the remaining cooking time t of the food is 0. If not, continue to detect the moisture content of the food and return to step S4. If yes, execute step S8. Step S8: Cooking is finished.

6. The cooking method applicable to a baking electric oven according to claim 5, characterized in that, A temperature measuring device is provided inside the electric oven box body, and the temperature measuring device can detect the real-time temperature of the food during the cooking process. Step S3 further includes: starting the temperature measuring device to detect the real-time temperature of the food; Step S6 includes: adjusting the remaining cooking time t of the food according to the moisture content and temperature of the food.

7. The cooking method applicable to a baking electric oven according to claim 5, characterized in that, The current moisture content obtained in step S3 is the moisture content value corrected by the correction curve model, and the correction curve model is obtained by fitting the theoretical attenuation curve of the food microwave attenuation amount and the moisture content with the measured attenuation curve.

8. The cooking method applicable to a baking electric oven according to claim 7, characterized in that, The theoretical attenuation curve is obtained by formula (9): （9） where A is the energy attenuation amount, in units of db, d is the thickness of the food material, in units of mm, and a is the attenuation constant, obtained by formula (2) or (3). （2） where λ is the microwave wavelength and ε is the dielectric property of the food to be measured, is the tangent value of the phase angle of the complex dielectric constant; （3）。 9. The cooking method applicable to a baking electric oven according to claim 7, characterized in that, The method for obtaining the measured attenuation curve includes: Step ST1: Divide the same kind of food materials into several groups according to the moisture content. Each group has two portions. The weight, size, and moisture content of the two food materials in the same group are the same, and the moisture content of the food materials in different groups is different. Step ST2: For the two food materials in the same group, one is completely dried by the drying method to obtain its moisture content data, and the other is dried by the microwave transmission method to obtain its microwave attenuation data; repeat the above operations until all the food materials in all groups are processed. Step ST3: Fit the moisture content data and the microwave attenuation data in step ST2 to obtain the measured attenuation curve. Step ST4: Repeat steps ST1 to ST3 for different food materials to obtain the measured attenuation curves corresponding to different food materials.

10. The cooking method applicable to a baking electric oven according to claim 7, characterized in that, The microwave attenuation data in step ST3 includes the microwave attenuation amount, and the microwave attenuation amount is obtained by formula (8): （8） Among them, A represents the microwave attenuation, P in represents the input power before the microwave penetrates the food, P out represents the output power after the microwave penetrates the food, U in represents the input voltage before the microwave penetrates the food, P out represents the output voltage after the microwave penetrates the food.

11. The cooking method applicable to a baking electric oven according to claim 6, characterized in that, Before step S4 and after step S3, it further includes: Step S30: Determine whether at least one of the acquisition intervals of the food moisture content and the acquisition interval of the food temperature in step S3 is less than the first preset time interval. If yes, execute step S4; if not, execute step S31. Step S31: When the acquisition interval of the food moisture content is greater than or equal to the first preset time interval, perform a self-check on the state of the microwave sensor in the moisture content detection system; when the acquisition interval of the food temperature is greater than or equal to the first preset time interval, perform a self-check on the temperature sensor in the temperature measuring device. Step S32: Give an alarm error according to the self-check result, and then execute step S8.

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