CN111867169B - Radio frequency heating control method based on double sources and double frequencies and radio frequency heating device - Google Patents
Radio frequency heating control method based on double sources and double frequencies and radio frequency heating device Download PDFInfo
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- H—ELECTRICITY
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- H05B6/00—Heating by electric, magnetic or electromagnetic fields
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- H05B6/062—Control, e.g. of temperature, of power for cooking plates or the like
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
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Abstract
The invention discloses a radio frequency heating control method and a radio frequency heating device based on double sources and double frequencies, which comprise the following steps: controlling a first radio frequency heating module to emit electromagnetic waves in a first frequency band; controlling a second radio frequency heating module to emit electromagnetic waves in a second frequency band; during which the two rf heating modules each adjust the phase of their emitted electromagnetic waves. The two radio frequency heating modules are designed to emit electromagnetic waves in different working frequency bands to heat or cook food together, so that the characteristics of the electromagnetic waves in the two frequency bands are complementary, the problems of insufficient heating depth and uneven heating existing in the process of heating the food by using the electromagnetic waves in a single frequency band are solved, and the heating efficiency can be obviously improved. Meanwhile, the phase of the electromagnetic waves emitted by the two radio frequency heating modules is continuously adjusted, so that the heat distribution in the heating cavity is more uniform, the heating quality of the radio frequency heating device can be further improved, and the user experience is improved.
Description
Technical Field
The invention belongs to the technical field of heating devices, relates to a radio frequency heating technology, and particularly relates to a heating control technology applied to a radio frequency heating device.
Background
With the rapid development and the becoming mature of the rf technology, the heating devices (such as electric ovens, microwave ovens, etc.) designed based on the rf heating technology have been developed and gradually attracted attention. The rf heating technology, an upgraded version of the microwave heating technology using a magnetron as a radiation source, is a technology for heating food using electromagnetic waves emitted from a solid semiconductor source. The solid semiconductor source can effectively adjust and control the power, frequency and phase of the electromagnetic wave emitted by the solid semiconductor source, thereby being more beneficial to improving the heating quality of the heating device.
However, in the existing rf heating device, electromagnetic waves emitted by the rf heating module inside the device are all in a single frequency band and a single phase. When heating food, the electromagnetic wave with a single frequency band and a single phase has disadvantages such as insufficient heating depth, uneven heating, low heating efficiency, etc., which in turn causes the heating quality of the food to be affected.
In addition, during the working period of the radio frequency heating module, the existing radio frequency heating device cannot sense whether the radio frequency heating module normally operates according to the preset power. If the radio frequency heating module does not normally operate according to the preset power during the heating time set by the user or the operation period of the cooking program selected by the user, the food is overcooked or undercooked, and the use experience of the user is seriously influenced.
Disclosure of Invention
The invention aims to provide a radio frequency heating control technology based on double sources and double frequencies, and aims to solve the problems of insufficient food heating depth, uneven heating and low heating efficiency caused by single frequency and single phase of emitted electromagnetic waves of the conventional radio frequency heating device.
In order to solve the technical problems, the invention adopts the following technical scheme:
in one aspect, the present invention provides a dual-source dual-frequency based rf heating control method, including: controlling a first radio frequency heating module to emit electromagnetic waves in a first frequency band; controlling a second radio frequency heating module to emit electromagnetic waves in a second frequency band; during the period that the first radio frequency heating module emits electromagnetic waves in a first frequency band and the second radio frequency heating module emits electromagnetic waves in a second frequency band, the two radio frequency heating modules respectively adopt one of the following phase adjustment modes to adjust the phases of the electromagnetic waves emitted by the two radio frequency heating modules:
in the first mode, t1+ t2 is used as a phase adjustment period, in each phase adjustment period, the radio frequency heating module is controlled to emit electromagnetic waves of which the phases are changed in a set interval in a time period t1, receive the reflected electromagnetic waves, select a phase corresponding to the electromagnetic wave with the most energy absorbed as an optimal phase, and emit the electromagnetic waves at the optimal phase in the time period t 2;
and in the second mode, the radio frequency heating module is controlled to increase or decrease the phase of the electromagnetic wave cycle by taking M as a phase adjustment period, so that the phase of the electromagnetic wave is circularly changed between a set minimum value and a set maximum value.
In order to obtain better heating quality, the invention preferably arranges that the first radio frequency heating module works in a medium frequency area, and the second radio frequency heating module works in a high frequency area. That is to say that the first and second electrodes,
in the process of controlling the first radio frequency heating module to emit electromagnetic waves in a first frequency band, firstly, setting a bandwidth range A of emission frequency by taking 915MHz as a central frequency; secondly, taking T11+ T12 as the frequency adjustment period, and performing the following processes in each frequency adjustment period: in a time period T11, controlling the first radio frequency heating module to emit electromagnetic waves with the frequency changing within the bandwidth range A, receiving the reflected electromagnetic waves, and selecting the frequency corresponding to the electromagnetic waves with the most energy absorbed as an optimal frequency F1; and controlling the first radio frequency heating module to emit electromagnetic waves at the optimal frequency F1 in the T12 period.
Further, when the first radio frequency heating module selects the first mode to adjust the phase of the electromagnetic wave emitted by the first radio frequency heating module, the phase adjustment process of the first mode is executed in the T12 time interval of each frequency adjustment cycle, and T1+ T2 is less than or equal to T12; when the phase of the electromagnetic wave emitted by the first radio frequency heating module is adjusted by the mode two, the phase adjustment process of the mode two is executed in the T12 time interval of each frequency adjustment cycle; or the first radio frequency heating module is controlled to execute the phase adjustment process of the second mode in the whole working period, namely, the phase adjustment process and the frequency adjustment process of the first radio frequency heating module do not interfere with each other.
In the process of controlling the second radio frequency heating module to emit electromagnetic waves in the second frequency band, firstly, setting a bandwidth range B of an emission frequency by taking 2450MHz as a central frequency; secondly, taking T21+ T22 as a frequency adjustment period, and performing the following processes in each frequency adjustment period: in a time period T21, controlling the second radio frequency heating module to emit electromagnetic waves with the frequency changing within the bandwidth range B, receiving the reflected electromagnetic waves, and selecting the frequency corresponding to the electromagnetic waves with the most energy absorbed as an optimal frequency F2; and controlling the second radio frequency heating module to emit electromagnetic waves at the optimal frequency F2 in the T22 period.
Further, when the second radio frequency heating module selects the first mode to adjust the phase of the electromagnetic wave emitted by the first mode, the phase adjustment process of the first mode is executed in the T22 time interval of each frequency adjustment cycle, and T1+ T2 is less than or equal to T22; when the second radio frequency heating module selects the second mode to adjust the phase of the electromagnetic wave emitted by the second radio frequency heating module, executing the phase adjustment process of the second mode in the T22 time period of each frequency adjustment cycle; or the second radio frequency heating module is controlled to execute the phase adjustment process of the second mode in the whole working period, namely, the phase adjustment process and the frequency adjustment process of the second radio frequency heating module do not interfere with each other.
In order to stabilize the total transmitting power of the two radio frequency heating modules on the set power and solve the problems of food overcooking or unfamiliarity and the like caused by incapability of sensing whether the radio frequency heating modules normally operate according to the preset power, the invention further provides a power monitoring and stabilizing control method for the transmitting power of the first radio frequency heating module and the second radio frequency heating module. Namely, comprising: receiving set power; controlling the two radio frequency heating modules to emit electromagnetic waves, and adjusting the emission power of each radio frequency heating module to be half of the set power; determining the maximum value and the minimum value of the input current of each radio frequency heating module according to half of the set power; detecting the input current of each radio frequency heating module; when the input current of one of the radio frequency heating modules is larger than the maximum value of the input current of the radio frequency heating module, reducing the amplitude of the electromagnetic waves emitted by the radio frequency heating module so as to reduce the emission power of the radio frequency heating module; when the input current of one of the radio frequency heating modules is smaller than the minimum value of the input current of the radio frequency heating module, the amplitude of electromagnetic waves emitted by the radio frequency heating module is increased so as to increase the emission power of the radio frequency heating module.
As a preferred determination method of the input current maximum and minimum values: firstly, ensuring the normal operation of a first radio frequency heating module or a second radio frequency heating module; secondly, adjusting the transmitting power of the first radio frequency heating module or the second radio frequency heating module step by step, and detecting the normal fluctuation range of the input current of the first radio frequency heating module or the second radio frequency heating module during the period of working at each stage of transmitting power; then, determining a maximum wave peak value Ic and a minimum wave trough value It of the input current according to a normal fluctuation range of the input current corresponding to each level of emission power; and finally, determining the maximum value Imax and the minimum value Imin of the input current of the first radio frequency heating module or the second radio frequency heating module working under each level of transmitting power, namely: imax = Ic +. DELTA.I 1; imin = It- < Δ I2; wherein, Δ I1 and Δ I2 are current margins and are both positive values.
In another aspect, the present invention further provides a radio frequency heating apparatus, including a heating cavity, a first radio frequency heating module, a second radio frequency heating module, a first sensing module, a second sensing module, and a control module; the inner wall of the heating cavity is provided with a first radiator and a second radiator; the first radio frequency heating module emits electromagnetic waves into the heating cavity through a first radiator; the second radio frequency heating module emits electromagnetic waves into the heating cavity through a second radiator; the first sensing module senses the intensity of the electromagnetic wave transmitted through the first radiator and the intensity of the received reflected electromagnetic wave; the second sensing module senses the intensity of the electromagnetic wave transmitted through the second radiator and the intensity of the received reflected electromagnetic wave; the control module controls the first radio frequency heating module to emit electromagnetic waves in a first frequency band, controls the second radio frequency heating module to emit electromagnetic waves in a second frequency band, and adjusts the phases of the electromagnetic waves emitted by the two radio frequency heating modules by using a first mode or a second mode; wherein, the first mode is: taking t1+ t2 as phase adjustment periods, in each phase adjustment period, the control module controls the radio frequency heating module to emit electromagnetic waves of which the phases are changed in a set interval in a t1 time period, and detects a phase P corresponding to the electromagnetic wave of which the energy is absorbed most through the sensing module; taking the phase P as an optimal phase, and controlling a radio frequency heating module to emit electromagnetic waves at the optimal phase in a t2 time period; the second mode is as follows: and taking M as a phase adjustment period, and controlling the radio frequency heating module to increase or decrease the phase of the electromagnetic wave cycle by the control module so that the phase of the electromagnetic wave is circularly changed between a set minimum value and a set maximum value.
In order to obtain better heating quality, the invention preferably arranges that the first radio frequency heating module works in a medium frequency area, and the second radio frequency heating module works in a high frequency area. That is, the control module takes T11+ T12 as a frequency adjustment cycle, and in each frequency adjustment cycle, controls the first rf heating module to emit an electromagnetic wave with a frequency varying within a bandwidth range a in a period of T11, and detects a frequency F1 corresponding to the electromagnetic wave with the most energy absorbed by the first sensing module; taking the frequency F1 as an optimal frequency, and controlling a first radio frequency heating module to emit electromagnetic waves at the optimal frequency F1 within a T12 time period; wherein A is a bandwidth range set with 915MHz as a center frequency; meanwhile, the control module takes T21+ T22 as a frequency adjustment period, in each frequency adjustment period, the second radio frequency heating module is controlled to emit electromagnetic waves with the frequency changing within the bandwidth range B in the T21 period, and the frequency F2 corresponding to the electromagnetic wave with the most energy absorbed is detected through the second sensing module; taking the frequency F2 as an optimal frequency, and controlling a second radio frequency heating module to emit electromagnetic waves at the optimal frequency F2 within a T22 time period; wherein B is a bandwidth range set with 2450MHz as a center frequency.
In order to realize stable control on the transmitting power of the two radio frequency heating modules, the radio frequency heating device is also provided with a current detection module and a man-machine interface; the current detection module is used for respectively detecting the input current of the first radio frequency heating module and the input current of the second radio frequency heating module and sending the input currents to the control module; the human-computer interface receives the set power and sends the set power to the control module; the control module controls each radio frequency heating module to operate according to half of the set power, and determines the maximum value and the minimum value of the input current of each radio frequency heating module according to half of the set power; when the control module detects that the input current of one of the radio frequency heating modules is larger than the maximum value of the input current of the radio frequency heating module during the operation of the two radio frequency heating modules, the control module controls the amplitude of the electromagnetic waves emitted by the radio frequency heating module to be reduced so as to reduce the emission power of the radio frequency heating module; when the input current of one of the radio frequency heating modules is detected to be smaller than the minimum value of the input current of the radio frequency heating module, the amplitude of the electromagnetic waves emitted by the radio frequency heating module is controlled to be increased so as to increase the emission power of the radio frequency heating module.
Compared with the prior art, the invention has the advantages and positive effects that: the invention utilizes the characteristic that the optimal absorption frequency of each food to electromagnetic waves is different due to different dielectric constants of the food, designs two radio frequency heating modules to emit the electromagnetic waves in different working frequency bands and heat or cook the food together, thereby not only complementing the characteristics of the electromagnetic waves in the two frequency bands, but also solving the problems of insufficient heating depth and uneven heating when the food is heated by the electromagnetic waves in a single frequency band, and obviously improving the heating efficiency. Meanwhile, the phase of the electromagnetic waves emitted by the two radio frequency heating modules is continuously adjusted, so that the heat distribution in the heating cavity is more uniform, the heating quality of the radio frequency heating device can be further improved, and the user experience is improved.
Other features and advantages of the present invention will become more apparent from the detailed description of the embodiments of the present invention when taken in conjunction with the accompanying drawings.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic diagram of an embodiment of an RF heating apparatus according to the present invention;
FIG. 2 is a control flow chart of an embodiment of a dual-source dual-frequency based RF heating control method of the present invention;
figure 3 is a control flow diagram of one embodiment of a method of power control for a radio frequency heating module.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and examples.
It should be noted that the terms "first" and "second" in the description of the present invention are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Because the characteristics of the electromagnetic waves in different frequency bands are different, the lower the frequency of the electromagnetic waves is, the longer the wavelength is, the stronger the penetration capacity to food is, but the corresponding cooking efficiency and heating uniformity are reduced to a certain extent; the higher the frequency of the electromagnetic wave is, the shorter the wavelength is, the weaker the penetrating power to the food is, but the cooking efficiency and the heating uniformity of the food are improved to a certain degree. According to the current international application program of electromagnetic waves, the frequency bands which can be used for radio frequency heating application comprise 433MHz, 915MHz and 2450 MHz. At present, electromagnetic waves emitted by using a radio frequency heating technology in the market are all in a single frequency band, and the electromagnetic waves in the single frequency band have inherent defects of the frequency band when food is heated, so that the defects are difficult to overcome. In order to solve the defects of the prior art, the invention provides a radio frequency heating control technology based on double sources and double frequencies, two radio frequency heating modules are adopted to emit electromagnetic waves with different frequencies, and a phase adjustment technology is matched, so that the heating quality is obviously improved.
In this embodiment, a radio frequency heating device is taken as an example to specifically describe the dual-source dual-frequency based radio frequency heating control technology.
As shown in fig. 1, the radio frequency heating apparatus of this embodiment mainly includes a heating cavity, a first radiator AT1 and a second radiator AT2 installed on an inner wall of the heating cavity, and a main control board for controlling the two radiators AT1 and AT2 to emit electromagnetic waves. Wherein, two irradiators AT1 and AT2 are preferred to be arranged in the relative both sides of the inner wall of heating chamber, and the electromagnetic wave is heated to the food in the heating chamber in the common emission. The main control board is provided with an alternating current-direct current conversion module, a first radio frequency heating module RM1, a second radio frequency heating module RM2, a first sensing module, a second sensing module, a control module and other main components. The alternating current-direct current conversion module is used for being externally connected with an alternating current power supply AC, such as alternating current commercial power, converting the alternating current power supply AC into two direct current power supplies DC1 and DC2, respectively providing independent direct current power supplies for the two radio frequency heating modules RM1 and RM2, further converting the direct current power supplies into a low-voltage working power supply VCC, and supplying power to weak current loads such as the control module, the first sensing module and the second sensing module. The first radio frequency heating module RM1 and the second radio frequency heating module RM2 are respectively connected with the two radiating bodies AT1 and AT2 in a one-to-one correspondence manner, each radio frequency heating module RM1 and RM2 comprises an oscillator, a radio frequency power amplifier and other electronic components, wherein the oscillator can generate electromagnetic wave signals with different frequencies and different phases, the electromagnetic wave signals are sent to the radio frequency power amplifier to amplify the power of the electromagnetic wave signals, the electromagnetic waves are emitted through the radiating bodies AT1 or AT2 and fed into the heating cavity, and food in the heating cavity is heated.
Because the radio frequency heating modules RM1 and RM2 have the characteristics of adjustable emission frequency and phase of electromagnetic waves, the frequency and phase of the electromagnetic waves emitted by the two radio frequency heating modules RM1 and RM2 can be adjusted by the control module during the operation of the radio frequency heating device, so that the continuous change of the optimal absorption frequency and the optimal absorption phase of food in the cooking process is adapted, and the cooking quality of the food is further improved.
As a preferable design of this embodiment, the control module preferably controls the first radio frequency heating module RM1 to emit electromagnetic waves in a first frequency band, for example, to generate electromagnetic wave signals AT an operating frequency with a center frequency of 915MHz, and to feed the electromagnetic waves in a middle frequency band into the heating cavity through the first radiator AT 1; meanwhile, the control module may control the second rf heating module RM2 to emit electromagnetic waves in a second frequency band, for example, to generate an electromagnetic wave signal AT an operating frequency of 2450MHz, and to feed the electromagnetic waves in a high frequency band into the heating cavity through the second radiator AT 2. The food in the heating cavity is heated by the electromagnetic waves of the two frequency bands, so that the characteristics of the electromagnetic waves of the two frequency bands are complementary, and the requirements of three aspects of heating depth, heating uniformity and heating efficiency are met.
Since the optimal absorption frequency of the electromagnetic waves of different frequency bands of the food is constantly changed during the cooking process, in order to obtain better heating quality, the first sensing module and the second sensing module for sensing the signal intensity of the electromagnetic waves are disposed on the main control board in the embodiment, as shown in fig. 1. The first sensing module is connected with the first radiating body AT1 and used for sensing the intensity of the electromagnetic wave transmitted by the first radiating body AT1 and the intensity of the reflected electromagnetic wave received by the first radiating body AT 1; similarly, the second sensing module is connected to the second radiating body AT2 and configured to sense the intensity of the electromagnetic wave transmitted by the second radiating body AT2 and the intensity of the reflected electromagnetic wave received by the second radiating body AT 2. The control module can calculate the energy absorption of the food to the electromagnetic wave with the frequency according to the signal intensity of the electromagnetic wave with the same frequency when being transmitted and the signal intensity reflected back after being absorbed by the food. The frequency corresponding to the electromagnetic wave with the most energy absorption can be regarded as the optimal absorption frequency of the food in the cooking stage. The control module adjusts the first RF heating module RM1 to emit electromagnetic waves at its optimum absorption frequency in its operating frequency band (middle frequency band) and adjusts the second RF heating module RM2 to emit electromagnetic waves at its optimum absorption frequency in its operating frequency band (high frequency band), thereby further improving heating efficiency.
During the time that the two RF heating modules RM1, RM2 emit electromagnetic waves at their optimal absorption frequencies, further adjustments may be made to the phase of the electromagnetic waves emitted by the two RF heating modules RM1, RM2 to achieve better cooking uniformity. For the adjustment of the phase of the electromagnetic wave, the present embodiment prefers two adjustment modes, that is:
in the first mode, t1+ t2 is used as a phase adjustment period, in each phase adjustment period, the radio frequency heating modules RM1 and RM2 are controlled to emit electromagnetic waves with phases changing in a set interval in a t1 time period, the reflected electromagnetic waves are received by the radiation bodies AT1 and AT2, the phase corresponding to the electromagnetic wave with the most energy absorbed is selected as an optimal phase, and the radio frequency heating modules RM1 and RM2 are controlled to emit the electromagnetic waves with the optimal phase in a t2 time period;
and in the second mode, the radio frequency heating modules RM1 and RM2 are controlled to increase or decrease the phase of the electromagnetic wave cycle by taking M as a phase adjustment period, so that the phase of the electromagnetic wave is circularly changed between a set minimum value and a set maximum value.
During the operation of the two rf heating modules RM1 and RM2, the phases of the electromagnetic waves emitted by the two rf heating modules may be adjusted by selecting the same mode, or by selecting different modes. Of course, the second mode may be performed out of the frequency adjustment process and synchronized throughout the operation of the RF heating modules RM1, RM 2.
The heating control method of the present embodiment is described in detail below with reference to fig. 2, and specifically includes the following steps:
s201, determining the transmitting power of each radio frequency heating module RM1 and RM2 according to the set power, and controlling the two radio frequency heating modules RM1 and RM2 to be put into operation according to the determined transmitting power;
because the radio frequency heating module has the characteristic of adjustable electromagnetic wave emission power, when the radio frequency heating device is put into operation, the control module can be used for generating control signals according to the set power and sending the control signals to the two radio frequency heating modules RM1 and RM2 so as to control the sum of the emission power of the two radio frequency heating modules RM1 and RM2 to be equal to the set power. The set power can be directly input by a user through an interactive interface of the man-machine interface, or can be automatically generated by the control module according to the selected cooking mode after the user selects the cooking mode through the interactive interface of the man-machine interface.
The present embodiment will be specifically explained in the following paragraphs with respect to the transmission power control method of each rf heating module RM1, RM 2.
S202, controlling the first radio frequency heating module RM1 to emit electromagnetic waves in a first frequency band;
in this embodiment, the control module sets the bandwidth range A of the transmit frequency of the first RF heating module RM1 centered at 915 MHz. As a preferred embodiment, the bandwidth range A is preferably set between 902MHz and 928MHz.
Setting the frequency adjustment period of the first radio frequency heating module RM1 as T11+ T12, and executing the following frequency adjustment process by the control module in each frequency adjustment period:
and in the time period T11, controlling the first radio frequency heating module RM1 to emit electromagnetic waves with the frequency continuously changing in the bandwidth range A, and receiving the reflected electromagnetic waves with the same frequency by the first radiator AT 1. Sensing the intensity of the electromagnetic wave transmitted by the first radiator AT1 and the intensity of the same-frequency reflected electromagnetic wave received by the first radiator AT1 by using a first sensing module, and sending the intensity to a control module to determine the frequency F1 corresponding to the electromagnetic wave with the most energy absorbed, wherein the frequency is used as the optimal frequency F1;
and controlling the first radio frequency heating module RM1 to emit electromagnetic waves at the optimal frequency F1 during the T12 period so as to efficiently heat the food.
The electromagnetic wave frequency adjusting process is performed in a cycle of T11+ T12 until the heating process is finished.
S203, adjusting the phase of the electromagnetic wave emitted by the first radio frequency heating module RM 1;
the control module adjusts the phase of the electromagnetic wave emitted by the first radio frequency heating module RM1 in the T12 period of each frequency adjustment cycle in the process of adjusting the emission frequency of the first radio frequency heating module RM1 by taking T11+ T12 as the frequency adjustment cycle. The phase adjustment mode may adopt any one of the following two modes:
in the first mode, setting a phase adjustment period as T1+ T2, wherein T1+ T2 is less than or equal to T12; during each phase adjustment cycle, the control module performs the following phase adjustment process:
and controlling the first radio frequency heating module RM1 to emit electromagnetic waves with the phases continuously changed in a set interval in the time period t 1. As a preferred embodiment, the set interval may be set to 0 ° to 360 °. Then, the reflected electromagnetic wave with the same frequency is received by the first radiator AT 1. Sensing the intensity of the electromagnetic wave transmitted by the first radiating body AT1 and the intensity of the same-frequency reflected electromagnetic wave received by the first radiating body AT1 by using a first sensing module, and sending the intensity to a control module to determine a phase A1 corresponding to the electromagnetic wave with the most energy absorbed, wherein the phase A1 is taken as an optimal phase A1;
and controlling the first radio frequency heating module RM1 to emit electromagnetic waves at the optimal phase A1 in the t2 period.
Since the heating chamber is filled with a plurality of electromagnetic waves of the same frequency, when two or more same-frequency electromagnetic waves are synthesized, different phases determine whether to strengthen or counteract the same-frequency electromagnetic waves, and thus, phase adjustment is important. The phase adjustment technology of the mode one is adopted, so that the continuous change of the optimal absorption phase of food in the cooking process can be adapted, and better heating quality can be obtained.
And in the second mode, the first radio frequency heating module RM1 is controlled to increase or decrease the phase of the electromagnetic wave cycle by taking M as a phase adjustment period, wherein M < T12, so that the phase of the electromagnetic wave is changed cyclically between the set minimum value and the set maximum value. For example, in the first phase adjustment period, the first radio frequency heating module RM1 is controlled to emit electromagnetic waves with the phase N; in the second phase adjustment period, the first radio frequency heating module RM1 is controlled to emit electromagnetic waves with the phase being N +1 or N-1; and so on, until the phase of the electromagnetic wave emitted by the first radio frequency heating module RM1 increases from a minimum value (e.g., 0 °) to a maximum value (e.g., 360 °), or decreases from the maximum value (e.g., 360 °) to the minimum value (e.g., 0 °), or repeats according to this rule to make the heating distribution more uniform.
For the phase adjustment process of the mode two, the phase adjustment process may not be performed in the period T12 of each frequency adjustment cycle, but the frequency adjustment and the phase adjustment may be performed in parallel, and the control module controls the first rf heating module RM1 to perform the frequency adjustment process and the phase adjustment process simultaneously during the whole operation period of the first rf heating module RM 1.
S204, controlling the second radio frequency heating module RM2 to emit electromagnetic waves in a second frequency band;
the process S202 and the process S204 of the present embodiment are not executed sequentially.
In this embodiment, the control module sets the bandwidth B of the transmitting frequency of the second RF heating module RM2 at 2450MHz as the center frequency. As a preferred embodiment, the bandwidth range B may be set between 2400mhz to 2500 mhz.
Setting the frequency adjustment period of the second radio frequency heating module RM2 as T21+ T22, and executing the following frequency adjustment processes by the control module in each frequency adjustment period:
and in the time period T21, controlling the second radio frequency heating module RM2 to emit electromagnetic waves with the frequency continuously changing in the bandwidth range B, and receiving the reflected electromagnetic waves with the same frequency by the second radiator AT 2. Sensing the intensity of the electromagnetic wave transmitted by the second radiator AT1 and the intensity of the same-frequency reflected electromagnetic wave received by the second radiator AT2 by using a second sensing module, and sending the intensities to a control module to determine the frequency F2 corresponding to the electromagnetic wave with the most energy absorbed, and taking the frequency F2 as the optimal frequency F2;
and controlling the second radio frequency heating module RM2 to emit electromagnetic waves at the optimal frequency F2 for the time period T22 so as to efficiently heat the food.
The electromagnetic wave frequency adjustment process is cyclically performed with a period of T21+ T22 until the heating process is finished.
S205, adjusting the phase of the electromagnetic wave emitted by the second radio frequency heating module RM 2;
the control module adjusts the phase of the electromagnetic waves emitted by the second radio frequency heating module RM2 in the T22 period of each frequency adjustment cycle in the process of adjusting the emission frequency of the second radio frequency heating module RM2 with the T21+ T22 as the frequency adjustment cycle. Wherein, the phase adjustment mode can adopt any one of the following two modes:
in the first mode, setting a phase adjustment period as T1+ T2, wherein T1+ T2 is less than or equal to T22; during each phase adjustment period, the control module performs the following phase adjustment processes:
in a time period t1, controlling the second radio frequency heating module RM2 to emit electromagnetic waves of which phases are continuously changed in a set interval (for example, 0-360 °), and receiving the reflected electromagnetic waves of the same frequency by using the second radiator AT 2; sensing the intensity of the electromagnetic wave transmitted by the second radiating body AT2 and the intensity of the same-frequency reflected electromagnetic wave received by the second radiating body AT2 by using a second sensing module, and sending the intensities to a control module to determine a phase A2 corresponding to the electromagnetic wave with the most energy absorbed, and taking the phase A2 as an optimal phase A2;
and controlling the second radio frequency heating module RM2 to emit the electromagnetic waves in the optimal phase A2 in the period of t 2.
And in the second mode, the second radio frequency heating module RM2 is controlled to increase or decrease the phase of the electromagnetic wave cycle by taking M as a phase adjustment period, wherein M < T22, so that the phase of the electromagnetic wave is changed cyclically between the set minimum value and the set maximum value. For example, in the first phase adjustment period, the second RF heating module RM2 is controlled to emit electromagnetic waves with the phase N; in the second phase adjustment period, controlling the second radio frequency heating module RM2 to emit electromagnetic waves with the phase being N +1 or N-1; and so on until the phase of the electromagnetic waves emitted by the second radio frequency heating module RM2 increases from a minimum value (e.g., 0 °) to a maximum value (e.g., 360 °), or decreases from the maximum value (e.g., 360 °) to the minimum value (e.g., 0 °), or repeats cyclically according to this rule to make the heating distribution more uniform.
For the phase adjustment process of the mode two, it may not be performed during the period T22 of each frequency adjustment cycle, but the frequency adjustment and the phase adjustment may be performed in parallel, and the control module may control the second rf heating module RM2 to perform the frequency adjustment process and the phase adjustment process simultaneously during the whole operation of the second rf heating module RM 2.
After the control module controls the radio frequency heating module to operate, whether the radio frequency heating module normally operates according to the preset power cannot be known. In order to effectively sense the transmitting power of the rf heating module, the present embodiment provides two current detection modules A1 and A2, which respectively detect the input currents I and I 'of the two rf heating modules RM1 and RM2 and send the input currents I and I' to the control module, indirectly reflect the power changes of the two rf heating modules RM1 and RM2 by using the fluctuation changes of the input currents I and I ', and adjust the transmitting power of the rf heating module RM1 or RM2 by increasing or decreasing the amplitude of the electromagnetic wave output by the rf heating module RM1 or RM2 when the input current I or I' is abnormal. In the process of adjusting the transmitting power of the radio frequency heating module RM1 or RM2, the change of the input current I and I 'is also taken as a judgment reference, and when the input current I and I' returns to the normal fluctuation range, the adjustment process of the amplitude of the electromagnetic wave can be ended. At this time, the transmission powers RM1 and RM2 of the rf heating modules are adjusted to be close to the predetermined powers, thereby achieving stable control of the transmission powers of the rf heating modules RM1 and RM 2.
The following describes in detail the power control method for the two rf heating modules RM1 and RM2 with reference to fig. 3, and specifically includes the following steps:
(I) test phase
S301, confirming that the two radio frequency heating modules RM1 and RM2 are not in failure, and controlling the two radio frequency heating modules RM1 and RM2 to normally operate one by one.
S302, gradually adjusting the transmitting power of each radio frequency heating module RM1/RM 2;
in this embodiment, the range of the transmission power (0 to the maximum power) corresponding to the normal operation of each rf heating module RM1/RM2 may be divided into intervals, for example: the power supply is divided into three large intervals of low power, medium power and high power; or finely divided to form five, ten or more different intervals. The finer the interval division, the more stable the power control.
The control module generates a control signal to adjust the transmitting power of the radio frequency power amplifier in each radio frequency heating module RM1/RM2 so as to control each radio frequency heating module RM1/RM2 to work under different transmitting powers, i.e. the transmitting power of each radio frequency heating module RM1/RM2 is adjusted step by step to work in different power intervals.
S303, detecting the normal fluctuation range of the input current of each radio frequency heating module RM1/RM2 during the work of each stage of transmitting power;
when the radio frequency heating module RM1/RM2 works in a certain power interval, the control module can control the emission power of the radio frequency heating module RM1/RM2 to continuously change in the interval, and in the power adjusting process, the input current I/I 'of the radio frequency heating module RM1/RM2 is detected in real time, the normal fluctuation range of the input current I/I' is recorded, and then the maximum wave peak value Ic/Ic 'and the minimum wave trough value It/It' of the input current corresponding to the emission power of each stage (each interval) are determined.
S304, determining the maximum value Imax/Imax 'and the minimum value Imin/Imin' of the input current of each radio frequency heating module RM1/RM2 working under each stage of transmitting power;
in the embodiment, the maximum value Imax/Imax 'and the minimum value Imin/Imin' of the input current of the rf heating module RM1/RM2 operating at each stage of the transmitting power are determined according to the maximum peak value Ic/Ic 'and the minimum valley value It/It' of the input current corresponding to each stage of the transmitting power, that is,
Imax=Ic+△I1；
Imin=It-△I2；
Imax'=Ic'+△I1；
Imin'=It'-△I2；
wherein, Δ I1 and Δ I2 are current margins and are positive values, and Δ I1 and Δ I2 may be equal or different. Therefore, a normal fluctuation range [ Imin, imax ]/[ Imin ', imax ' ] of the input current I/I ' of each stage of the radio frequency heating module RM1/RM2 is determined and recorded to the control module for being called in the future practical application process.
In this embodiment, in order to facilitate searching for the maximum value Imax/Imax 'and the minimum value Imin/Imin' of the input current corresponding to the transmitting power of each stage of the rf heating module RM1/RM2, in this embodiment, it is preferable that the control module establishes and stores the corresponding relationship between the transmitting power and the input current for the maximum value Imax/Imax 'and the minimum value Imin/Imin' of the input current corresponding to the transmitting power of each stage.
The corresponding relation can be a comparison table between the emission power and the input current, and the maximum value Imax/Imax 'and the minimum value Imin/Imin' of the input current, which correspond to different set powers, are determined by adopting a table look-up method; or forming a storage address mapping relation, accessing different storage addresses according to different transmitting powers, and calling the input current Imax/Imax 'and the minimum value Imin/Imin' stored in the storage addresses. Of course, the present embodiment is not limited to the above examples.
S305, determining an input current limit value Iext/Iext' of each radio frequency heating module RM1/RM 2;
in order to avoid the rf heating module RM1/RM2 from being damaged due to overheating, the present embodiment preferably determines the maximum acceptable input current according to the maximum heating value that can be borne by the internal devices of the rf heating module RM1/RM2, forms the input current limit value Iext/Iext ', and stores the input current limit value Iext/Iext' in the control module for being called in the future practical application process.
(II) practical application stage
S306, receiving set power, and distributing the transmitting power of each radio frequency heating module RM1 and RM2 to be half of the set power;
in this embodiment, the set power input by the user or the set power corresponding to the selected cooking mode is the sum of the emission powers of the two rf heating modules RM1 and RM 2. The present embodiment determines the transmission power of each of the RF heating modules RM1, RM2 to be half the set power in an evenly divided manner.
S307, determining the maximum value and the minimum value of the input current of each radio frequency heating module RM1 and RM2 according to half of the set power;
the control module of this embodiment may determine the maximum value and the minimum value of the input current of each of the rf heating modules RM1 and RM2 by using the corresponding relationship between the transmission power and the input current, which is pre-stored in the control module, according to a half of the set power. For example, when the first radio frequency heating module RM1 works at half of the set power, the maximum value of the corresponding input current is Imax, and the minimum value is Imin; when the second radio frequency heating module RM2 works at half of the set power, the maximum value of the corresponding input current is Imax ', and the minimum value is Imin'.
S308, controlling each radio frequency heating module RM1 and RM2 to be put into operation according to half of the set power;
in this embodiment, the control module generates two paths of control signals according to half of the set power, and sends the two paths of control signals to the two radio frequency heating modules RM1 and RM2, respectively, controls the two radio frequency heating modules RM1 and RM2 to start and operate, and adjusts the transmitting powers of the two radio frequency heating modules RM1 and RM2 to be half of the set power.
S309, detecting input currents I and I ' of each radio frequency heating module RM1 and RM2, and if I is larger than Iext or I ' > Iext ', cutting off direct current supply of the two radio frequency heating modules RM1 and RM2 and controlling the radio frequency heating device to enter a protection state; otherwise, executing the subsequent process;
during the operation of the two radio frequency heating modules RM1, RM2, the two current detection modules A1, A2 detect the input currents I, I 'of the two radio frequency heating modules RM1, RM2 in real time and send the input currents I, I' to the control module. The control module retrieves the pre-stored input current limit values Iext, iext' for each of the rf heating modules RM1, RM 2.
If the input current I of the first radio frequency heating module RM1 is larger than the limit value Iext thereof, or the input current I 'of the second radio frequency heating module RM2 is larger than the limit value Iext', the control module immediately cuts off the direct current supply of the two radio frequency heating modules RM1 and RM2, controls the two radio frequency heating modules RM1 and RM2 to stop running and enters a protection state. By the design, on one hand, the radio frequency heating module which breaks down can be prevented from being damaged due to overheating, and on the other hand, the problem that food cannot be eaten and can only be discarded due to the fact that the food is not normally heated according to the set power can be prevented.
If the input current I for the first RF heating module RM1 is ≦ Iext, and the input current I 'for the second RF heating module RM2 is ≦ the limit value Iext', then the subsequent stabilizing control procedure for the transmit power is performed.
S310, adjusting the amplitude of the electromagnetic waves emitted by the two radio frequency heating modules RM1 and RM2 according to the input currents I and I' of the two radio frequency heating modules RM1 and RM 2;
in this embodiment, if the first current detecting module A1 detects that the input current I of the first rf heating module RM1 fluctuates within the interval [ Imin, imax ], the control module determines that the transmitting power of the first rf heating module RM1 is stable and is substantially equal to half of the set power. During this time, the control module can control the first rf heating module RM1 to keep the current working state and continue to operate, and emit electromagnetic waves according to half of the set power to cook the food in the heating cavity.
Similarly, if the second current detecting module A2 detects that the input current I ' of the second rf heating module RM2 fluctuates within the interval [ Imin ', imax ' ], the control module determines that the transmission power of the second rf heating module RM2 is stable and is substantially equal to half of the set power. During this period, the control module can control the second rf heating module RM2 to keep operating in the current working state, and emit electromagnetic waves with half the set power to cook the food in the heating cavity.
If the first current detecting module A1 detects that the input current I > Imax of the first RF heating module RM1, it indicates that the transmitting power of the first RF heating module RM1 is increased. At this time, the control module may generate an amplitude adjustment signal, and send the amplitude adjustment signal to the first radio frequency heating module RM1 to control the first radio frequency heating module RM1 to reduce the amplitude of the electromagnetic wave emitted by the first radio frequency heating module RM1, so as to achieve the purpose of reducing the emission power of the first radio frequency heating module RM 1.
Similarly, if the second current detecting module A2 detects that the input current I '> Imax' of the second RF heating module RM2, it indicates that the transmitting power of the second RF heating module RM2 is increased. At this time, the control module may generate an amplitude adjustment signal, and send the amplitude adjustment signal to the second radio frequency heating module RM2 to control the second radio frequency heating module RM2 to reduce the amplitude of the electromagnetic wave emitted by the second radio frequency heating module RM2, so as to achieve the purpose of reducing the emission power of the second radio frequency heating module RM 2.
If the first current detecting module A1 detects that the input current I < Imin of the first RF heating module RM1, it means that the transmitting power of the first RF heating module RM1 is decreased. At this time, the control module may generate an amplitude adjustment signal, and send the amplitude adjustment signal to the first radio frequency heating module RM1 to control the first radio frequency heating module RM1 to increase the amplitude of the electromagnetic waves emitted by the first radio frequency heating module RM1, so as to achieve the purpose of increasing the emission power of the first radio frequency heating module RM 1.
Similarly, if the second current detecting module A2 detects that the input current I '< Imin' of the second rf heating module RM2, it indicates that the transmitting power of the second rf heating module RM2 becomes smaller. At this time, the control module may generate an amplitude adjustment signal, and send the amplitude adjustment signal to the second radio frequency heating module RM2 to control the second radio frequency heating module RM2 to increase the amplitude of the electromagnetic wave emitted by the second radio frequency heating module RM2, so as to achieve the purpose of increasing the emission power of the second radio frequency heating module RM 2.
In the process of adjusting the amplitude of the electromagnetic waves emitted by the two radio frequency heating modules RM1 and RM2 according to the input currents I and I 'of the two radio frequency heating modules RM1 and RM2, the control module can control the two radio frequency heating modules RM1 and RM2 to gradually increase or decrease the amplitude of the electromagnetic waves according to the set adjustment quantity Δ a, and receive the input currents I and I' detected by the two current detection modules A1 and A2 after each amplitude adjustment. When the input current I/I 'of the RF heating module RM1/RM2 with the deviated emission power returns to within the normal interval, for example, the input current I is within the [ Imin, imax ] interval and the input current I' is within the [ Imin ', imax' ] interval, it means that the deviated emission power of the RF heating module RM1/RM2 returns to about half of the set power. At this time, the control module may stop the amplitude adjustment process for the RF heating modules RM1/RM2 to stabilize the emission power of the RF heating modules RM1/RM2 at about half the set power.
Therefore, power control of the two radio frequency heating modules RM1 and RM2 is achieved, the two radio frequency heating modules RM1 and RM2 can be guaranteed to operate stably at half of preset set power all the time, and then the heating quality of the whole radio frequency heating device is improved.
In this embodiment, the power control and frequency adjustment of the two RF heating modules RM1, RM2 are performed simultaneously and without interfering with each other.
Certainly, more radio frequency heating modules and radiating bodies can be arranged in the radio frequency heating device, and the high-quality heating requirements of different types of food can be met by adjusting the frequency difference of the electromagnetic waves emitted by each radio frequency heating module.
It should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (5)
1. A radio frequency heating control method based on double sources and double frequencies is characterized by comprising the following steps:
controlling a first radio frequency heating module to emit electromagnetic waves in a first frequency band, taking T11+ T12 as a frequency adjustment period, and executing in each frequency adjustment period: in a T11 time period, controlling a first radio frequency heating module to emit electromagnetic waves with the frequency changing in a first frequency band, receiving reflected electromagnetic waves, and selecting a frequency corresponding to the electromagnetic waves with the most energy absorbed as an optimal frequency F1; controlling a first radio frequency heating module to emit electromagnetic waves at the optimal frequency F1 in a T12 period;
controlling the second radio frequency heating module to emit electromagnetic waves in a second frequency band, taking T21+ T22 as a frequency adjustment period, and executing in each frequency adjustment period: in a time period T21, controlling the second radio frequency heating module to emit electromagnetic waves with the frequency changing in a second frequency band, receiving the reflected electromagnetic waves, and selecting the frequency corresponding to the electromagnetic waves with the most energy absorbed as an optimal frequency F2; controlling a second radio frequency heating module to emit electromagnetic waves at the optimal frequency F2 in a T22 period;
the first radio frequency heating module performs the following electromagnetic wave phase adjustment processes in the T12 period of each frequency adjustment cycle thereof and the second radio frequency heating module in the T22 period of each frequency adjustment cycle thereof:
taking t1+ t2 as a phase adjustment period, controlling each radio frequency heating module to emit electromagnetic waves of which the phases are changed in a set interval in a t1 time period and receive the reflected electromagnetic waves in each phase adjustment period, selecting the phase corresponding to the electromagnetic wave of which the energy is absorbed most as an optimal phase, and emitting the electromagnetic waves at the optimal phase in a t2 time period;
controlling the two radio frequency heating modules to emit electromagnetic waves, and adjusting the emission power of each radio frequency heating module to be half of the set power;
determining the maximum value and the minimum value of the input current of each radio frequency heating module according to half of the set power;
detecting the input current of each radio frequency heating module; when the input current of one of the radio frequency heating modules is larger than the maximum value of the input current of the radio frequency heating module, reducing the amplitude of the electromagnetic waves emitted by the radio frequency heating module so as to reduce the emission power of the radio frequency heating module; when the input current of one of the radio frequency heating modules is smaller than the minimum value of the input current of the radio frequency heating module, increasing the amplitude of electromagnetic waves emitted by the radio frequency heating module so as to increase the emission power of the radio frequency heating module;
the method for determining the maximum value and the minimum value of the input current comprises the following steps:
ensuring the first radio frequency heating module or the second radio frequency heating module to normally operate;
gradually adjusting the transmitting power of the first radio frequency heating module or the second radio frequency heating module;
detecting the normal fluctuation range of input current of the first radio frequency heating module or the second radio frequency heating module during the period of each stage of transmitting power;
determining a maximum wave peak value Ic and a minimum wave trough value It of the input current according to a normal fluctuation range of the input current corresponding to each level of emission power;
determining the maximum value Imax = Ic +. DELTA.I 1 of the input current and the minimum value Imin = It-DELTA.I 2 of the input current when the first radio frequency heating module or the second radio frequency heating module works at each level of transmitting power; wherein, Δ I1 and Δ I2 are current margins and are positive values.
2. The dual-source dual-frequency-based radio frequency heating control method according to claim 1, wherein the first frequency band is a frequency band set with 915MHz as a center frequency; the second frequency band is a frequency band set with 2450MHz as a center frequency.
3. A radio frequency heating apparatus, comprising:
the heating cavity is provided with a first radiator and a second radiator on the inner wall;
the first radio frequency heating module emits electromagnetic waves into the heating cavity through a first radiator;
the second radio frequency heating module emits electromagnetic waves into the heating cavity through a second radiator;
a first sensing module that senses intensity of the electromagnetic wave transmitted through the first radiator and intensity of the received reflected electromagnetic wave;
a second sensing module that senses the intensity of the electromagnetic wave transmitted through the second radiator and the intensity of the received reflected electromagnetic wave;
the current detection module is used for respectively detecting the input current of the first radio frequency heating module and the input current of the second radio frequency heating module;
a control module that executes the following control processes:
taking T11+ T12 as a frequency adjustment period, controlling the first radio frequency heating module to emit electromagnetic waves with frequencies changing in a first frequency band within a T11 time period in each frequency adjustment period, and detecting a frequency F1 corresponding to the electromagnetic waves with the most energy absorbed through the first sensing module; taking the frequency F1 as an optimal frequency, and controlling a first radio frequency heating module to emit electromagnetic waves at the optimal frequency F1 within a T12 time period;
taking T21+ T22 as a frequency adjustment period, controlling the second radio frequency heating module to emit electromagnetic waves with frequencies changing in a second frequency band within a T21 time period in each frequency adjustment period, and detecting a frequency F2 corresponding to the electromagnetic waves with the most energy absorbed through the second sensing module; taking the frequency F2 as an optimal frequency, and controlling a second radio frequency heating module to emit electromagnetic waves at the optimal frequency F2 within a T22 time period;
respectively controlling the first radio frequency heating module to execute the following electromagnetic wave phase adjustment processes in the T12 time period of each frequency adjustment cycle of the first radio frequency heating module and the T22 time period of each frequency adjustment cycle of the second radio frequency heating module:
taking t1+ t2 as a phase adjustment period, controlling each radio frequency heating module to emit electromagnetic waves of which the phases are changed in a set interval in each phase adjustment period at the time period of t1, and detecting a phase P corresponding to the electromagnetic waves of which the energy is absorbed most through a sensing module; taking the phase P as an optimal phase, and controlling each radio frequency heating module to emit electromagnetic waves at the optimal phase in a t2 time period;
controlling the two radio frequency heating modules to emit electromagnetic waves, and adjusting the emission power of each radio frequency heating module to be half of the set power;
determining the maximum value and the minimum value of the input current of each radio frequency heating module according to half of the set power;
receiving the input current of each radio frequency heating module detected by the current detection module, and reducing the amplitude of electromagnetic waves emitted by one radio frequency heating module when the input current of the radio frequency heating module is greater than the maximum value of the input current of the radio frequency heating module so as to reduce the emission power of the radio frequency heating module; when the input current of one of the radio frequency heating modules is smaller than the minimum value of the input current of the radio frequency heating module, increasing the amplitude of the electromagnetic waves emitted by the radio frequency heating module so as to increase the emission power of the radio frequency heating module;
the method for determining the maximum value and the minimum value of the input current comprises the following steps:
ensuring the first radio frequency heating module or the second radio frequency heating module to normally operate;
gradually adjusting the transmitting power of the first radio frequency heating module or the second radio frequency heating module;
detecting a normal fluctuation range of input current of a first radio frequency heating module or a second radio frequency heating module during working at each stage of transmitting power;
determining the maximum wave peak value Ic and the minimum wave trough value It of the input current according to the normal fluctuation range of the input current corresponding to each stage of transmitting power;
determining the maximum value Imax = Ic +. DELTA.I 1 of the input current and the minimum value Imin = It-DELTA.I 2 of the input current when the first radio frequency heating module or the second radio frequency heating module works at each level of transmitting power; wherein, Δ I1 and Δ I2 are current margins and are both positive values.
4. A radio frequency heating device according to claim 3,
the first frequency band is a frequency band set by taking 915MHz as a central frequency;
the second frequency band is a frequency band set with 2450MHz as a center frequency.
5. A radio frequency heating apparatus as claimed in claim 3 or 4, further comprising:
and the human-computer interface receives the set power and sends the set power to the control module.
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| ES2369312T3 (en) * | 2008-12-19 | 2011-11-29 | Whirlpool Corporation | MICROWAVE OVEN ALTERNATING BETWEEN DEFAULT MODES. |
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