CN109221882B - Switch matching module and defrosting device using same - Google Patents
Switch matching module and defrosting device using same Download PDFInfo
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- CN109221882B CN109221882B CN201811295301.6A CN201811295301A CN109221882B CN 109221882 B CN109221882 B CN 109221882B CN 201811295301 A CN201811295301 A CN 201811295301A CN 109221882 B CN109221882 B CN 109221882B
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- 238000010257 thawing Methods 0.000 title claims abstract description 108
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- 235000013305 food Nutrition 0.000 abstract description 44
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- 229910002601 GaN Inorganic materials 0.000 description 1
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
- A23L3/00—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
- A23L3/36—Freezing; Subsequent thawing; Cooling
- A23L3/365—Thawing subsequent to freezing
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- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Polymers & Plastics (AREA)
- Control Of High-Frequency Heating Circuits (AREA)
- Freezing, Cooling And Drying Of Foods (AREA)
- Electric Ovens (AREA)
Abstract
The invention provides a switch matching module and a defrosting device using the same, comprising an inductor L3, wherein one end of the inductor L3 is connected with a power output end; the inductor L5, one end of the inductor L5 is connected with the other end of the inductor L3; one end of the first bypass is connected with the power output end, and the other end of the first bypass is grounded; and one end of the second bypass is connected with the other end of the inductor L3, and the other end of the second bypass is grounded. Compared with the prior art, the invention has the following advantages: 1) The tuning resolution can be improved, the compensation range of food can be widened, and the number of switches is reduced, so that the cost is reduced. 2) The L-shaped and L-shaped matching circuit can greatly reduce the number of switching devices and the performance requirements, and has excellent improvements on the use safety, the service life and the like of the thawing device.
Description
Technical Field
The invention relates to the field of household electrical appliances, in particular to a switch matching module and a defrosting device using the same.
Background
The existing thawing methods by heat conduction mainly comprise air thawing, water soaking thawing, refrigerator refrigerating thawing and thawing plate thawing, which have long thawing time and are easy to grow bacteria (except refrigerator refrigerating thawing) in the environment of 5-60 ℃ in the thawing process, so that the sanitary condition cause anxiety is achieved; thawing plate thawing, food surface is by contacting with thawing plate conduction heat (the time is quicker) fast, but the inside self heat conductivity of food is low, inside and outside homogeneity is poor, and food that the thickness is big is especially obvious. Although the microwave oven thaws by an electromagnetic field permeation mode, the time is faster, the internal and external uniformity is particularly poor due to high frequency, the surface temperature is high, and bacteria can be quickly propagated.
The prior art chinese invention patent (application publication number: CN107684007 a) discloses a defrosting system having a lumped inductance matching network and an operating method thereof, the defrosting system comprising: an RF signal source; an electrode proximate to a chamber within which a load to be thawed is positioned; a transmission path between the RF signal source and the electrode; and an impedance matching network electrically coupled along the transmission path between the output of the RF signal source and the electrode. The system also includes a power detection circuit coupled to the transmission path and configured to detect reflected signal power along the transmission path. The system controller is configured to modify an inductance value of the impedance matching network based on the reflected signal power to reduce a ratio of the reflected signal power to a forward signal power. The impedance matching network includes a plurality of fixed value lumped inductors positioned within a fixed inductor region.
Disclosure of Invention
The invention aims to provide a switch matching module and a defrosting device using the same, which solve the technical problems.
In order to solve the technical problems, the invention provides a switch matching module, which comprises an inductor L3, wherein one end of the inductor L3 is connected with a power output end; the inductor L5, one end of the inductor L5 is connected with the other end of the inductor L3; one end of the first bypass is connected with the power output end, and the other end of the first bypass is grounded; and one end of the second bypass is connected with the other end of the inductor L3, and the other end of the second bypass is grounded.
Preferably, the first bypass comprises: the power output end is connected with one end of the inductor L1; and one end of the inductor L2 is connected with the other end of the inductor L1, and the other end of the inductor L2 is grounded.
Preferably, the second bypass includes: and one end of the inductor L4 is connected with the other end of the inductor L3, and the other end of the inductor L4 is grounded.
Preferably, the second bypass includes: the inductor L4, one end of the inductor L4 is connected with the other end of the inductor L3; and one end of the inductor L6 is connected with the other end of the inductor L4, and the other end of the inductor L6 is grounded.
Preferably, the inductance L3 is an adjustable inductance; the inductor L5 is a fixed inductor; the inductor L1 is a fixed inductor; the inductor L2 is an adjustable inductor; the inductance L4 is a fixed inductance.
Preferably, the inductance L3 is a fixed inductance; the inductor L5 is a fixed inductor; the inductor L1 is a fixed inductor; the inductor L2 is an adjustable inductor; the inductor L4 is a fixed inductor; the inductance L6 is an adjustable inductance.
A thawing apparatus comprising at least: the defrosting device comprises a defrosting cavity, wherein the defrosting cavity is required to be made of or contain a metal material, and a working chamber is arranged in the defrosting cavity; the control unit is arranged on the defrosting cavity; the radio frequency power output module is arranged on the defrosting cavity and is communicated with the control unit; the measuring unit is respectively connected with the control unit and the radio frequency power output module; the switch matching module is respectively connected with the control unit and the measuring unit, and the optimal state of impedance matching of the output end of the radio frequency power output module can be found by switching the switch devices in the switch matching module; the power supply module is respectively connected with the control unit, the radio frequency power output module and the switch matching module; the radiation mechanism is connected with the switch matching module and is arranged below the working chamber; the switch matching module is the switch matching module.
Preferably, the power module includes: an adjustable voltage section, a fixed voltage section and a control interface in communication with the control unit.
Preferably, the radiation mechanism comprises: a radiation unit disposed below the working chamber in a noncontact manner; and the feed unit is connected with the radiation unit and the switch matching module.
Preferably, the radiating element is a metal panel, a metal mesh or a metal bending piece.
Preferably, the initial output frequency of the radio frequency power output module is 40.68MHz, the step length of adjustment is 5 KHz-10 KHz, and the best matched thawing frequency point can be found through scanning frequency.
Preferably, the thawing chamber is determined to be in an empty or full state by initially adjusting the switching state of the switching matching module and the optimally matched frequency point of the radio frequency power output module after matching.
Preferably, whether thawing is completed is judged by detecting the stability degree of the amplitude and the phase change rate of the dispersion parameter S 11 at the output end of the radio frequency power output module.
Compared with the prior art, the invention has the following advantages:
1) The tuning resolution can be improved, the compensation range of food can be widened, and the number of switches is reduced, so that the cost is reduced.
2) The L-shaped and L-shaped matching circuit can greatly reduce the number of switching devices and the performance requirements, and has excellent improvements on the use safety, the service life and the like of the thawing device.
Drawings
Other characteristic objects and advantages of the invention will become more apparent from reading the detailed description of non-limiting embodiments, given with reference to the following drawings.
FIG. 1 is a schematic diagram of a defrosting apparatus according to the present invention;
FIG. 2 is a schematic view of a cavity structure containing a radiation unit in the thawing apparatus of the present invention;
FIG. 3 is a schematic view of a cavity structure of the thawing apparatus of the present invention, which includes a bent radiation unit;
FIG. 4 is a block diagram of the system connections between the defrost device modules of the present invention;
FIG. 5 is a block diagram of the controllable power source module connection of the defrosting apparatus of the present invention;
FIG. 6 is a circuit diagram of a switch matching module of the thawing apparatus according to an embodiment of the present invention;
fig. 7 is a circuit diagram of a switch matching module of the thawing apparatus according to a second embodiment of the present invention;
FIG. 8 is a schematic diagram of an implementation of an adjustable inductor of the thawing apparatus of the present invention;
FIG. 9 is a basic flow chart of the electric frequency modulation of the defrosting device of the invention;
fig. 10 is a basic operation flow chart of the defrosting apparatus of the present invention.
In the figure:
1-thawing cavity 2-fan 3-switch matching module
4-Radio frequency power output module 5-power module 6-control unit
7-Display Module 8-working Chamber 9-food
10-Insulating plate 11-radiating element 12-feeding element
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept.
Fig. 1 is a schematic view of the defrosting apparatus, which depicts one implementation of the layout of the various modules, the radiation assembly being located inside the defrosting chamber 1, fixed by a low-loss insulating plate 10; the switch matching module 3 is positioned at the rear of the thawing cavity 1, a cable or a conductive rod is connected with the radiation assembly through a through hole on the rear side surface, an insulating sleeve is fixed on the through hole, and the cable or the conductive rod needs to pass through the insulating sleeve to prevent contact with the thawing cavity 1; the radio frequency power output module 4, the power module 5 is positioned on the right side of the defrosting cavity 1, and the cable connects the power module 5 with the switch matching module 3 through a through hole on the right side surface; the control unit 6 is positioned on the front right side of the thawing cavity 1, and the cable connects the thawing cavity 1 with the radio frequency power output module 4, the power module 5 and the switch matching module 3 through small holes on the front right side of the thawing cavity 1; the UI is positioned on the control unit 6, and is provided with keys and a display module 7 which are convenient for the user to control; the fan 2 is arranged at the rear and right side of the defrosting cavity 1, so that air cooling and heat dissipation can be conveniently provided for the switch matching module 3, the radio frequency power output module 4 and the power module 5. Food 9 is placed on an insulating plate 10 in the working chamber 8 for thawing. The open side for placing food 9 is provided with a door body structure which can be opened and closed, and the leakage of radio frequency energy can be effectively prevented when the door body structure is closed. The thawing chamber 1 and the door structure need to be or contain metal materials, so that the thawing chamber can play a role of shielding. Based on the above description, a person skilled in the art will understand that the implementation is relatively simple and the layout is not limited thereto.
Fig. 2 is a schematic view of a cavity containing a radiating element 11, the radiating element 11 being fixed to an insulating plate 10, below the cavity. The radiating element 11 may be a metal panel, or a metal mesh, or a metal bent piece (e.g. fig. 3), etc. The edge electric field intensity of the metal panel is maximum, and the edge part can be bent downward appropriately, so that the part with large electric field intensity is distributed downward, the uniformity of the thawed food 9 is improved, and the metal panel with the bent edge downward is shown in fig. 3. The shape of the metal panel is not limited and may be circular, square, etc., and the shape of the metal panel also determines the electric field distribution in the cavity, i.e., affects the uniformity of heating of the food 9. The radiating element 11 has a high rf voltage and the radiating element 11 cannot be in electrical contact with the cavity. The food 9 is placed on the insulating plate 10 such that the food 9 is closer to the radiating element 11, the electric field around the radiating element 11 is stronger, and the thawing efficiency is high. One end of the feeding unit 12 is connected with the radiation unit 11, the other end is connected with the switch matching module 3, the feeding unit can be a metal rod, a cable or the like, and the feeding unit cannot be in electrical contact with the cavity. Zin is the input impedance of the feed port to the antenna end, and varies with the weight, temperature, shape and type of the food 9, so that in order to enable Zin to be in a good matching state with the rf power output module 4 all the time, an impedance conversion module, i.e. a matching module, must be added between them, and meanwhile, the measurement module is used for monitoring the current matching state.
Fig. 4 is a block diagram of the system connections between the defrost modules. The power module 5 converts the commercial power into a plurality of direct current power sources with stable output and is responsible for supplying power to the radio frequency power output module 4, the control unit 6 and the switch matching module 3. The control unit 6 is a control center of the whole system and is used for completing all the functions of state monitoring, data analysis, function control, UI (user interface) man-machine interaction, remote monitoring and the like of the system; specifically, the output frequency and the power of the radio frequency power output module 4 are controlled, the opening of the power supply module 5 and the output voltage are controlled, the output voltage and the current of the power supply are read at the same time, the switch switching state in the switch matching module 3 is controlled, and the radio frequency parameters obtained by measurement of the measurement unit are received and processed. The radio frequency power output module 4 can convert direct current electric energy into radio frequency high power electromagnetic field energy. The measuring unit is used for monitoring the matching state between the output end of the radio frequency power output module 4 and the feed end of the radiating unit 11. The switch matching module 3 receives the switch control signal from the control unit 6, and converts the impedance of the feeding end of the radiating unit 11 to a state close to the impedance of the output end of the radio frequency power output module 4. The radio frequency high power electromagnetic field energy passes through the measuring unit and the switch matching module 3 reaches the cavity containing the radiating element 11. The radiation unit 11 is responsible for efficiently and uniformly transmitting radio frequency power to the food 9, and the high-speed changing radio frequency oscillating electromagnetic field forces molecules, ions and the like in the food 9 to do intense movement so as to heat; the metal cavity constrains electromagnetic field energy in the cavity, prevents electromagnetic fields from radiating outside the cavity and simultaneously achieves rapid and uniform thawing and heating of food 9. Components and devices providing other functions, such as heat sinks, may also be included in practicing the present invention.
Fig. 5 to 8 show the implementation methods of the main functional modules of the thawing device of the present invention, which are merely referred to by those skilled in the art, and the implementation methods are not limited thereto.
Fig. 5 is a controllable power source module composed of a radio frequency power output module 4, a control unit 6, a measurement unit and a power supply module 5, wherein the radio frequency power output module 4 comprises a controllable signal source and a power amplification link, and the power supply module 5 comprises an adjustable voltage part and a fixed voltage part.
The radio frequency controllable signal source in the radio frequency power output module 4 can output a weak radio frequency signal with adjustable frequency, the control signal output by the control unit 6 controls the output state of the radio frequency signal, such as an on/off signal, the output frequency of the control signal and the like, and the frequency range of the invention is 40.66 MHz-40.70 MHz, and other suitable frequency bands can be selected similarly; the radio frequency signal output by the controllable signal source is required to be amplified by a power amplification link to generate radio frequency high-power energy for thawing, the power amplification link is generally composed of two to three stages of power amplification transistors, and the power amplification transistors are more commonly metal oxide semiconductor transistors or gallium nitride transistors; the control unit 6 provides controllable gate voltages for these transistors, the adjustable voltage part of the power module 5 provides variable drain voltages for the transistors, and the control unit 6 controls the power module 5 to output the adjustable voltage. The control unit 6 may control the magnitude of the output power of the rf power output module by changing the magnitude of the gate voltage or the drain voltage.
The measuring unit is used for detecting radio frequency parameters of the output end of the power amplification link, specifically the magnitude and the phase of output and reflected power, and S 11. The control unit 6 knows the impedance state of the feed end of the radiating element 11 and its matching with the output end of the power amplifying link by means of these radio frequency parameters. The implementation method of the measuring unit is a radio frequency coupler.
The power module 5 comprises at least an adjustable voltage part, a fixed voltage part and a control interface. The control unit 6 can set the output voltage of the adjustable voltage part through the power control interface, the adjustable voltage part provides drain voltage for the power amplification link in the radio frequency power output module 4, the control unit 6 can also read the set voltage and the supplied current, thus the power module 5 and the power amplification link can be monitored at any time through the closed loop processing to ensure the reliability and safety of the power source of the thawing system. The control unit 6 requires a fixed voltage part in the power supply module 5 to provide it with a stable normally open fixed voltage.
In the invention, the subsystem consisting of the radio frequency power output module 4, the control unit 6, the measuring unit and the power supply module 5 in fig. 5 is a power source system which has controllable frequency, adjustable power, measurable matching, stability and reliability and has important and wide application value. In the present invention, the frequency can be scanned to find the corresponding thawing frequency point that best matches the impedance of the food 9, referred to herein as an electrical fm match.
The rf power output by the rf power output module 4 must first pass through the switch matching module 3 before effectively reaching the radiating element. The switch matching module 3 is a passive adjustable part, when the impedance matching state is bad and reaches the threshold set by system software, the switch switching control signal output by the control unit 6 switches the multi-way switch to search the best matching state of the output end of the radio frequency power output module 4, and the function of the switch matching module is to compensate the impedance difference caused by different types, sizes, positions, shapes and temperatures of the foods 9, so that the change of the foods 9 is automatically compensated in the whole process. The best state found for impedance matching with the food item 9 is switched by a switch, referred to herein as an electrically tuned match.
The switch matching module 3 is an inductive matching network, and comprises a fixed inductive part and an adjustable inductive part. The adjustable inductance part is provided with a plurality of switches controlled by the control unit 6, each switch is correspondingly connected with a controlled inductance in parallel, and the opening and closing of the switches can determine the state of whether the controlled inductances are connected or not or change the topology structure of the circuit; at the same time, the switch matching module 3 has a plurality of fixed inductances which are not connected in parallel with the switch, namely are not controlled by the control unit 6, and the fixed inductances can play a role of sharing current or voltage.
The specific implementation method of the switch matching module 3 of the invention is shown in fig. 6-8, fig. 6 and 7 are two effective matching implementation modes, the port 1 is connected with the output end of the measuring unit, and the port 2 is connected with the feed input end of the radiating unit 11. The above-mentioned method is mainly aimed at realizing matching requirements by using simplest method, at the same time providing two matching schemes for those skilled in the art, and convenient for laying out and wiring hard circuit board. The following detailed description will be readily understood by those skilled in the art. Although specific implementations of these two matches are described herein, implementations of the invention are not limited to the topology network shown.
In fig. 6, one end of the port1 is first connected in parallel with a first bypass which is connected in series by a fixed inductor L1 and a variable inductor L2 and then grounded; a fixed inductor L3 is connected in series between the port1 and the node 1; the node 1 is connected in parallel with a second bypass which is connected in series by a fixed inductor L4 and a variable inductor L6 and then grounded; a fixed inductance L5 is connected in series between node 1 and port 2. The fixed inductor L1 and the fixed inductor L4 respectively limit the minimum inductance of the first bypass and the second bypass, so as to prevent the first bypass and the second bypass from causing total reflection of radio frequency energy due to direct grounding short circuit, and the radio frequency energy cannot be effectively transmitted to the radiating unit 11 at the rear end of the port 2.
In fig. 7, one end of the port 1 is first connected in parallel with a first bypass which is connected in series by a fixed inductor L1 and a variable inductor L2 and then grounded; an adjustable inductor L3 is connected in series between the port 1 and the node 2; a second bypass which is grounded by the fixed inductor L14 is connected in parallel with the node 2; a fixed inductance L5 is connected in series between node 2 and port 2. Also, the fixed inductance L1 defines an inductance minimum of the first bypass, preventing the first bypass from causing total reflection of radio frequency energy due to a direct ground short, so that the radio frequency energy cannot be effectively transferred to the radiating element 11 at the rear end of the port 2.
Fig. 8 is a specific implementation of the adjustable inductance L2, the adjustable inductance L3, and the adjustable inductance L6 of the adjustable inductance portion in fig. 6 or fig. 7. The adjustable inductor is formed by connecting a plurality of inductors in series from small to large, each inductor is connected in parallel with a switch controlled by a control unit 6 to be turned on or turned off, the power module 5 can provide stable voltage for the switches, and the switch can be a high-power relay. When a certain switch is closed, the corresponding inductor connected in parallel with the certain switch is short-circuited by the switch, and the inductor is not connected into the circuit; conversely, when a certain switch is turned on, the corresponding inductor connected in parallel with the switch is connected into the circuit. The opening and closing of the switch controls the magnitude of the inductance value access. In order to make the inductance values be connected in a controllable linear trend, the inductance values can be increased in equal proportion in a relationship of about twice, the minimum inductance value determines the minimum adjustment step length, and the number of inductance connections or the number of switches determines the maximum value of the whole adjustable inductance.
The basic circuit topologies in fig. 6 and 7 are formed by connecting two L-type inductance matching networks in series. However, the positions of the fixed inductance portion and the adjustable inductance portion differ, and the corresponding mechanism is as follows.
The port 1 is connected with the output end of the measuring unit, namely, the first bypass is close to the radio frequency power output module 4, the voltage of the port 1 is relatively low, and the maximum value of the current on the bypass can be effectively controlled by controlling the minimum serial inductance value L1 of the first bypass, so that the first bypass is used as an adjustable inductance part to reduce the index requirements of the voltage resistance and the current of the switching device, and the implementation is easy. The first bypass is mainly used for adjusting the matching quality, namely the magnitude of S 11. The smaller the capacitive reactance of the input impedance of the input ends of the port 2 and the radiating unit 11 is, the larger the resistance is, and the larger the inductance value of the first bypass access is; and conversely, the accessed inductance value is minimum.
The port 2 is connected with the feed end of the radiating unit 11 arranged in the metal cavity, and the series resistance in the input impedance corresponding to the feed end is very small, or the parallel resistance is very large, namely the Q value in the cavity is very large. Resulting in a large voltage and current at port 2. The inductor L5 is directly connected to the input of the radiating element 11, and needs to withstand a large current, which is not suitable as an adjustable inductance part. The current on the inductor L5 is the sum of the current on the inductor L3 and the current phasor on the second bypass, and the inductor corresponding to the second bypass and the inductor L3 can be used as the adjustable inductor.
In fig. 6, an inductance L3 connected in series between the port 1 and the node 1 is a fixed inductance, and the second bypass corresponds to an adjustable inductance. Since the second bypass is close to port 2, i.e. radiating element 11, the second bypass is mainly used to adjust the shift of the S 11 resonant frequency. For example, in the invention, the matching frequency point is returned to the range of 40.6 MHz-40.70 MHz, the adjustable inductance L6 is increased, and the S 11 resonant frequency is shifted to the lower frequency direction; on the contrary, the tunable inductance L6 becomes smaller, and the S 11 resonance frequency shifts to a higher frequency direction. The inductor L4 can effectively control the maximum value of the current on the bypass, and reduce the index requirements of the withstand voltage and the current of the switching device. The first bypass and the second bypass in fig. 6 are divided, the first bypass is used for adjusting the amplitude of S 11, and the second bypass is used for adjusting the offset of the resonant frequency of S 11. In general, the inductance L2 and the inductance L6 have 4 to 7 controlled inductances or switches, and the inductance L2 and the inductance L6 range from about 10nH to 800nH, and the magnitude of the inductance is related to the input impedance corresponding to the feeding end. The inductance L4 and the inductance L5 range from about 200nH to 500nH, the inductance L3 ranges from about 400nH to 800nH, and the inductance L1 ranges from about 80nH to 150 nH.
In fig. 7, the inductance L3 connected in series between the port 1 and the node 2 is an adjustable inductance, and the inductance L4 corresponding to the second bypass is a fixed inductance, where the adjustable inductance L3 is closer to the port 1, i.e. the rf power output module 4 and the first bypass. Unlike fig. 6, the tunable inductors L2 and L3 can affect the magnitude of S 11 and the shift of the resonant frequency of S 11 at the same time. The number of controlled inductances or switches of the inductance L2 can thus be reduced to 2 to 5, and the number of controlled inductances or switches of the inductance L3 to 4 to 7.
It is found that the weight and temperature of the food 9 (affecting the dielectric constant of the food 9) have the greatest influence on the impedance of the input end of the radiation unit 11, and the more the food 9 is placed in the thawing chamber or the higher the temperature of the food 9 (not exceeding 0 ℃), the smaller the corresponding capacitive reactance, and the larger the resistance; when no load is applied, the corresponding capacitive reactance is the largest and the resistance is the smallest. Therefore, the adjustable inductor L6 or the adjustable inductor L3 and the electric frequency modulation optimal matching frequency can be used for predicting whether the thawing chamber is in an empty or full state. For example, when the adjustable inductance L6 or the adjustable inductance L3 is the largest and the matching frequency is the lowest, the thawing chamber may correspond to the no-load state, when the adjustable inductance L6 or the adjustable inductance L3 is the smallest and the matching frequency is the highest, the thawing chamber may correspond to the full-load state.
The radio frequency output power in the radio frequency power output module 4 has a certain frequency adjustment range, for example 40.66 MHz-40.70 MHz, and the output frequency is controlled by the control unit 6. Fig. 9 is a basic flow chart of electric frequency modulation of the thawing apparatus of the present invention, in which the frequency of the rf power output module is kept unchanged during the electric tuning of the switch, and the default initial frequency is 40.68MHz. The electrical frequency modulation matching is generally performed after the electrical tuning finds the best match, and the specific steps are as follows:
Step one: keeping the switch state after electric tuning matching unchanged, and recording the amplitude value S 0 of the current color dispersion parameter S 11;
Step two: adjusting the output frequency of the radio frequency power output module 4, wherein the step of the electric frequency modulation is about 5KHz to 10KHz, and the amplitude S L、SR of S 11 of two nearest frequency points (such as 40.675MHz and 40.685 MHz) about the initial frequency is read;
Step three: comparing the numerical values of S 0、SL and S R;
step four: if S 0 is minimum, the optimal frequency point is the initial frequency of 40.68MHz, and the electric frequency modulation matching is completed;
Step five: if S L or S R is minimum, the control unit controls the radio frequency power output module to select the smaller side frequency direction of S 11, and gradually sweep the frequency; if the amplitude of S 11 is still gradually reduced, the frequency sweep is continued to be carried out in the direction, if the amplitude of S 11 is started to be increased, the frequency sweep is stopped, and the smallest frequency point of S 11 is the electric tuning optimal matching frequency point, so that electric frequency modulation matching is completed.
In the electric frequency modulation matching process, the controllable power source module can adjust and find the best matched signal output frequency. As an auxiliary match, it mainly plays two roles: 1. the specific idea is to increase the minimum frequency shift amount of electric tuning matching, namely step size, under the condition of not changing the compensation range and precision, by reducing the number of switches for compensating S 11 resonance frequency shift, namely the number of switches in the adjustable inductor L6 or the adjustable inductor L3, and then by using continuous electric tuning matching assistance, the optimal matching state of crossing certain food 9 loads (with different weights or temperatures) in the tuning process is prevented; 2. another effect is to widen the compensation range of the food 9, if too much food 9 is thawed, the adjustable inductance L6 or the adjustable inductance L3 is minimized, and at this time, the frequency can be reduced to 40.66MHz for matching. In a word, as auxiliary electric frequency modulation, the tuning resolution can be improved, the compensation range of the food 9 can be widened, and the number of switches is reduced, so that the cost is reduced.
The control unit 6, which performs all state monitoring, data analysis, function control and UI human-computer interaction of the system, may comprise one or more processors for control, memory, display module 7, voice module, key module, communication interface, etc. for controlling
1) The state monitoring comprises ① door body structure switch monitoring, wherein the opening and closing of the micro switch is controlled through the opening and closing of the door body structure, the control signal is used for monitoring whether the micro switch is closed or not at all, and if the door body structure is opened, a power supply cannot be opened, and a thawing program cannot be operated; ② The impedance state of the feed port is monitored at any time through the radio frequency measurement parameters fed back by the measurement unit, so that the radio frequency power output by the radio frequency power output module 4 can be effectively transmitted to the radiation unit 11.
2) And (3) data analysis, namely collecting the output frequency, forward power, reverse power and phase difference of the radio frequency measurement module, so as to calculate the amplitude and phase of the chromatic dispersion parameter S 11. The impedance state of the foods 9 of different kinds, temperatures, shapes, weights is analyzed.
3) A function control for controlling the output of the power supply by a power supply control signal outputted from the control unit 6; the grid voltage output by the control unit 6 controls the magnitude of each grid voltage of the power amplification link; the control unit 6 outputs radio frequency signals to control the output state and the frequency state of the controllable signal source; the switch switching control signal output by the control unit 6 controls the on-off of the switch on the switch matching module 3 and the like.
4) The UI interaction module comprises a display module 7, a key module, a knob, a voice module and the like. The remote monitoring system is used for receiving signals input by a user, the user selects functions through keys and knobs, and the remote monitoring system can monitor conveniently and real-time through a remote monitoring module.
The thawing device can be added with other auxiliary components, heat dissipation components, temperature measurement components and the like. The heat radiation component comprises a fan 2, an air duct with reasonable design and a plurality of heat radiation structural parts with lower heat resistance, and radiates heat of a power module 5, a radio frequency power output module 4 and a switch matching module 3 in the system. The temperature measuring component comprises a thermistor temperature measuring part, an infrared temperature measuring part and the like, wherein the thermistor temperature measuring part mainly aims at the power supply module 5 and the radio frequency power output module 4, the infrared temperature measuring part mainly aims at food materials needing thawing, and measured temperature data are transmitted to the control unit 6 for monitoring and analysis, so that the reliable operation of the system is ensured.
Fig. 10 is a basic operation flowchart of the defrosting apparatus. The UI interaction module of the control unit 6 can receive a conventional/quick/tattooing/manual instruction sent by a user, after receiving a signal for starting thawing, the control unit 6 sets the output frequency of the radio frequency power output module 4 to be an initial frequency (for example, 40.68 MHz), controls the power to be low power output, controls the switch matching module 3 to perform electric tuning matching, continuously switches the matching state, and simultaneously reads the amplitude and the phase of the feeding end S 11 of the radiating unit 11, which are measured by the measuring unit, and the magnitude of the output and reflected power of the radio frequency power output module 4, so as to judge whether the matching state is good or bad, and generally, the smaller the value of S 11 is, the better the matching state is. The purpose of the low power output is to prevent the irreversible damage of the device caused by high power when the matching state is not good, but the power output cannot be too small to ensure the detection precision of the radio frequency measurement module, and the power is related to the selection of the power amplifier and the switching device. After the optimal matching is found by electric tuning, the switch state is kept unchanged, electric frequency modulation matching is carried out, the step of electric frequency modulation matching is about 5KHz to 10KHz, when the electric frequency modulation matching is carried out, S 11 matching values of two nearest frequency points about the initial frequency are read first, the sizes of the two nearest frequency points are compared, then the frequency points are gradually swept towards the direction of increasing or decreasing the frequency at the side of reducing S 11, and the electric frequency modulation is completed until the frequency point with the minimum S 11 is found.
After the best match is found, the device will analyze if the matching condition is abnormal, which is manifested as bad matching condition, e.g., S 11 has a value higher than-8 dB. If the matching state is abnormal, two conditions generally exist, namely no-load and failure. The switching state of the switch matching module 3 corresponding to the idle load is fixed, and under the fault condition, the switching state of the switch is random, so that the device is easy to identify.
When the matching state is normal, the device can record the matching state of the current switch and increase the radio frequency output power to defrost the food 9. In the thawing process, the impedance of the input end of the electrically-controlled radiation device is changed due to the change of the temperature of the food 9, so that the power output by the radio frequency power output module is changed, the output power can be increased or reduced greatly, and the device is likely to work under high load or the thawing time is increased, so that stable output power needs to be maintained regularly. If the detected adaptation degree is higher than the set threshold value due to the impedance change in the thawing process, the device reduces the output power of the rf power output module, reenters the searching and setting mode of the best match, and sets the output frequency of the rf power output module 4 to the initial frequency (e.g., 40.68 MHz) again before performing the electric tuning matching.
The radio frequency parameters in the thawing process are stored and analyzed at fixed time during thawing, wherein the radio frequency parameters mainly refer to the amplitude and phase information of S 11 detected by the radio frequency measurement module. In order to ensure the uniform quality of the thawing of the food 9, the output power of the rf power output module needs to be continuously adjusted during the thawing process. After thawing, the device turns off the signal source, the power supply and the radio frequency power output module 4 and reminds the user of thawing completion.
Whether thawing is complete is dependent on the thawing mode selected by the user. When the user selects manual thawing, the system thaws according to the time set by the user or the set temperature. Thawing is completed when the thawing timer is reached to the upper time limit set by the user or the measured temperature of the food 9 reaches the upper temperature limit set by the user. When the user selects automatic thawing (regular/quick/tattooing), the system automatically judges whether thawing is completed or not according to the obtained change rate of the radio frequency parameters. During thawing, the feed input impedance of the radiating element 11 changes due to temperature changes of the food 9, resulting in a change of the measured S 11. However, as the temperature rises, the ice crystal state inside the food 9 is gradually converted into a flowing liquid state, a large amount of phase change occurs, the temperature rise of the food 9 is gradually reduced under the condition of absorbing the same energy, the change amplitude of S 11 is gradually reduced, and particularly, when the temperature of the food 9 is increased to a range from-2 ℃ to 0 ℃, S 11 is basically unchanged. Thus, by utilizing the characteristic that the temperature rise is gentle or the change of S 11 is gentle, it is possible to judge whether or not thawing of the food 9 is completed. The amplitude and phase of S 11 are continuously read and stored during thawing, and the variation of the amplitude and phase of S 11 is calculated, and if the variation has stabilized to a certain extent, thawing is completed. Experiments show that the invention is suitable for thawing tattoos (such as salmon, oyster and the like), and is particularly embodied in uniform and rapid thawing, and the freshness and the taste of original food materials can be greatly reserved.
It is worth mentioning that the device has a default upper limit for time and temperature for thawing the food 9, and if this default upper limit is reached, the device will stop thawing.
Compared with thawing equipment with lumped inductance matching network and operation method thereof in the prior art (application publication number: CN 107684007A), the technical scheme of the invention has the following advantages:
1. Differentiation of matching modes
The prior art adopts a mode of controlling the switch state of the impedance matching network through a controller to realize matching. The invention provides a mode of adopting electric frequency modulation matching after electric tuning matching, which has the very good advantages that:
1) The number of switches for compensating the S 11 resonance frequency offset is reduced, and meanwhile, the matching resolution can be improved, and the specific thought is to increase the minimum frequency shift amount of electric tuning matching, namely the step length, when the electric tuning matching is not increased, the step length of the switch tuning is about 90KHz, and the step length is increased by 40KHz through continuous electric tuning matching, so that the number of a plurality of switches can be reduced, and meanwhile, the step length of frequency modulation can be very small as 5KHz, so that the resolution of the electric tuning matching is greatly improved, the optimal matching state is found, and the defrosting efficiency is improved.
2) Another effect is to widen the food compensation range even if the system is able to defrost heavier or lighter foods.
In general, after the matching of the electric frequency modulation, the tuning resolution can be improved, the compensation range of food can be widened, and the number of switches can be reduced, so that the cost is reduced.
2. Distinction of matching circuits
The prior art adopts an L-type plus pi-type inductance matching circuit. The invention adopts the L-shaped and L-shaped inductance matching circuit, thus having very remarkable advantages:
1) From the topological structure, the method is simpler and more convenient to realize.
2) Functionally, both are matched functions, but the effects differ significantly. If the range of the food to be thawed is 0.1Kg to 2Kg, the range of the adjustable inductance of the L-shaped plus pi-shaped circuit far away from the radio frequency source end is as follows: 160nH-1429nH, and the range of the adjustable inductance of the L-shaped plus L-shaped circuit far away from the radio frequency source end is as follows: 160nH-305nH. It can be seen that the number of switches of the L-type plus L-type circuit can be correspondingly reduced under the condition of ensuring the same step length; meanwhile, under the condition of the same power, the current phase difference of the two circuits on the adjustable inductance branch is smaller, and the larger the inductance is, the voltage born by the switch is required to be increased, so that the index requirement of the L-shaped and L-shaped circuit on the switch is greatly reduced, and the thawing device is greatly helpful for realizing low cost.
3) The invention also changes the adjustable inductance branch into the inductance connected in series between the radio frequency input end and the intermediate node, such as the inductance L3 in fig. 7, which has the advantages that the adjustable inductance L3 and the adjustable inductance L2 can have positive influence on each other on the premise of not changing the matching range, and plays a role in greatly reducing the inductance value range of the adjustable inductance L2, namely reducing the number of the switches of the adjustable inductance L2.
In a word, the L-shaped and L-shaped matching circuit can greatly reduce the number of switching devices and the requirements on performance, and has excellent improvements on the use safety, the service life and the like of the thawing device.
The foregoing describes specific embodiments of the present application. It is to be understood that the application is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the application. The embodiments of the application and the features of the embodiments may be combined with each other arbitrarily without conflict.
Claims (5)
1. A defrosting apparatus, comprising at least:
the defrosting cavity is required to be made of or contain metal materials, and a working chamber is arranged in the defrosting cavity;
The control unit is arranged on the defrosting cavity;
the radio frequency power output module is arranged on the defrosting cavity and is communicated with the control unit;
The measuring unit is respectively connected with the control unit and the radio frequency power output module;
the switch matching module is respectively connected with the control unit and the measuring unit, and the optimal state of impedance matching of the output end of the radio frequency power output module can be found by switching the switch devices in the switch matching module;
the power supply module is respectively connected with the control unit, the radio frequency power output module and the switch matching module;
the radiation mechanism is connected with the switch matching module and is arranged below the working chamber;
the radiation mechanism includes:
a radiation unit disposed below the working chamber in a noncontact manner;
The feed unit is connected with the radiation unit and the switch matching module;
Judging whether the thawing chamber is in an empty or full state through initially adjusting the switching state of the switching matching module and the optimally matched frequency point of the radio frequency power output module after matching;
the switch matching module comprises:
the power output end is connected with one end of the inductor L3;
The inductor L5, one end of the inductor L5 is connected with the other end of the inductor L3;
one end of the first bypass is connected with the power output end, and the other end of the first bypass is grounded;
one end of the second bypass is connected with the other end of the inductor L3, and the other end of the second bypass is grounded;
The first bypass comprises:
The power output end is connected with one end of the inductor L1;
The inductor L2, one end of the inductor L2 is connected with the other end of the inductor L1, and the other end of the inductor L2 is grounded;
the second bypass includes:
The inductor L4, one end of the inductor L4 is connected with the other end of the inductor L3, and the other end of the inductor L4 is grounded; the inductor L3 is an adjustable inductor; the inductor L5 is a fixed inductor; the inductor L1 is a fixed inductor; the inductor L2 is an adjustable inductor; the inductor L4 is a fixed inductor;
Or, the second bypass includes:
The inductor L4, one end of the inductor L4 is connected with the other end of the inductor L3;
The inductor L6, one end of the inductor L6 is connected with the other end of the inductor L4, and the other end of the inductor L6 is grounded; the inductor L3 is a fixed inductor; the inductor L5 is a fixed inductor; the inductor L1 is a fixed inductor; the inductor L2 is an adjustable inductor; the inductor L4 is a fixed inductor; the inductance L6 is an adjustable inductance.
2. The thawing device of claim 1, wherein the power module comprises:
an adjustable voltage section, a fixed voltage section and a control interface in communication with the control unit.
3. The thawing device of claim 2, wherein the radiating elements are metal panels, metal grids, or metal bends.
4. The thawing device as defined in claim 1, wherein the initial output frequency of the radio frequency power output module is 40.68MHz, the step length is adjusted to be 5 KHz-10 KHz, and the thawing frequency point with the best match can be found by scanning the frequency.
5. The defrosting apparatus according to claim 1 or 4, wherein whether defrosting is completed is determined by detecting a degree of stability of a rate of change of an amplitude and a phase of the dispersion parameter S 11 at the output end of the rf power output module.
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