CN111043632A

CN111043632A - Intelligent microwave oven frequency selection method based on solid-state source

Info

Publication number: CN111043632A
Application number: CN201911384963.5A
Authority: CN
Inventors: 陈海东; 罗泽文; 车文荃; 薛泉
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2019-12-28
Filing date: 2019-12-28
Publication date: 2020-04-21

Abstract

The invention discloses a method for intelligently selecting frequency of a microwave oven based on a solid-state source, which is characterized by comprising the following steps of: 1) the solid-state microwave source outputs power with certain frequency and size to the feedback device; 2) comparing the size of the reflected power received by the feedback device to judge the power absorption degree of each frequency point; 3) and adjusting the solid state microwave source to achieve a specific output power and output frequency. The invention selects proper working frequency by extracting the reflected power of different frequencies based on the solid source microwave oven working at non-single frequency, thereby greatly improving the heating efficiency of the microwave oven.

Description

Intelligent microwave oven frequency selection method based on solid-state source

Technical Field

The invention relates to the technical field of microwave heating, in particular to a method for intelligently selecting frequency of a microwave oven based on a solid-state source.

Background

Generally, a microwave heating apparatus for home use converts electric energy into microwaves by using a magnetron therein, not a solid state microwave source, and the microwaves penetrate food at a certain oscillation frequency. When microwave is absorbed by food, because the food contains a certain amount of water which is composed of polar molecules, the polar molecules interact under the microwave field, the generated heat heats the surface and the interior of the food at the same time, and the temperature rise speed is high, thereby realizing the fast cooking of the food. The microwave oven is composed of oven body, oven cavity, magnetron, waveguide, power supply and oven door. The oven door can not only be used for preventing the leakage of microwave, but also form a resonant cavity with a certain space with the oven cavity for the interaction of food and microwave field. In the microwave heating equipment which is researched at present, for example, a microwave oven, commercial products basically realize heating technology by internally loading a magnetron with a frequency of 2450 MHz; commercial products typically use a frequency of 915 MHz. Generally, they all cook food using a single microwave source at a single frequency. Although the single heating mode can excite fields of a plurality of modes in the cavity, the number of excited mode fields is limited, and the problem of uneven heating caused by uneven mode distribution in the cavity is avoided.

Microwave ovens based on solid-state circuits, which allow to achieve an optimal heating effect by a flexible choice of different frequencies, are known from the published patent CN 109587861A. However, the output frequency of the broadband microwave source described in the patent only has a corresponding mapping relation with the thickness of the heated object, and the five operation modes are relatively fixed, and the specific frequency cannot be automatically selected through the magnitude of the reflected power.

Disclosure of Invention

In view of the deficiencies of the prior art, the present invention generally provides a frequency intelligent selection technique for microwave heating of a solid state source. In order to achieve the purpose, the technical scheme adopted by the invention is to adopt a broadband microwave power source or a plurality of microwave solid-state sources which work in a narrow band or a dot frequency mode. The power source is connected to the transmitting antenna, which may be one or more, through a microwave transmission line such as a cable or waveguide, or directly.

The invention is realized by at least one of the following technical schemes.

An intelligent selection method for frequency of a microwave oven based on a solid-state source comprises the following steps:

1) the solid-state microwave source outputs power with certain frequency and size to the feedback device;

2) comparing the size of the reflected power received by the feedback device to judge the power absorption degree of each frequency point;

3) and adjusting the solid state microwave source to achieve a specific output power and output frequency.

Further, the feedback device in step 1) includes a directional coupler, a power divider or a microwave energy receiving antenna built in the microwave oven.

Further, step 2) is to compare all or part of the reflected powers after the reflected power received by the feedback device is amplified by detection and converted and sampled by analog and digital signals, and determine which frequency point or frequency band has the smallest reflected power, and then heat the frequency point or frequency band.

Further, the solid microwave source is a microwave solid source or a plurality of microwave solid frequency sources which work in a broadband or a plurality of frequency points.

Further, the solid state microwave source is capable of adjusting the output power through adjustment of an external circuit.

When an object to be heated is placed in the heating furnace, the microwave power source is first controlled to automatically scan from low frequency to high frequency in a manner of low power output, for example, milliwatt level or several watt level. A feedback circuit or receiving antenna receives the reflected microwave energy. And outputs an analog voltage amplitude value by using microwave devices such as a detector.

Further, after the output voltage amplitude value is subjected to digital processing by the analog-to-digital converter, a specific working frequency point, such as the working frequency point with the minimum amplitude reflection, is found.

Further, according to the obtained specific working frequency point, the amplitude and frequency of the microwave solid-state source are adjusted by a method of selecting solid-state microwave sources with different working frequencies, high output power is selected, and emission is started.

When the object to be heated is continued for a while, the amplitude of the solid-state source is reduced to a lower power and is again swept from low frequency to high frequency, or high frequency to low frequency, or in segments, the operating frequency is again selected by the reflected power, and then the selected object again outputs a high power at a specific frequency for heating.

The steps are repeated until the heating is completed. The invention is characterized in that the reflected power is used to select a specific working frequency, so that the low reflection frequency is always in effect in the heating process, thereby improving the heating efficiency.

Compared with the prior art, the invention has the beneficial effects that: the frequency of the signal with the best heating effect can be selected based on the signal power received by the feedback device, and then the emission frequency of the solid-state microwave source is adjusted, so that the high efficiency of heating is realized.

Drawings

FIG. 1 is a schematic diagram of a method for intelligently selecting frequencies of a microwave oven based on a solid-state source according to an embodiment;

fig. 2 is a schematic diagram illustrating the operation of the present embodiment for obtaining feedback power by using a receiving antenna;

fig. 3 is a timing chart of the operation of the present embodiment.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.

A method for intelligent selection of frequency for a solid state source based microwave oven as shown in fig. 1, comprising the steps of:

1) the solid-state microwave source outputs power with certain frequency and size to the feedback device; the feedback device comprises a directional coupler, a power divider or a microwave energy receiving antenna which are arranged in the microwave oven. The solid microwave source is a microwave solid source or a plurality of microwave solid frequency sources with broadband or working at a plurality of frequency points.

2) Comparing the size of the reflected power received by the feedback device to judge the power absorption degree of each frequency point; specifically, the reflected power received by the feedback device enters an FPGA or DSP system after being amplified through detection and converted and sampled by analog and digital signals, the system compares all or part of the reflected power, judges which frequency point or frequency band has the minimum reflected power, and then heats the frequency point or frequency band

3) And adjusting the solid state microwave source to achieve a specific output power and output frequency. The solid-state microwave source can adjust the output power through the adjustment of the numerical value of the resistance-capacitance element in the external bias circuit.

The operation principle diagram for obtaining feedback power by using a receiving antenna as shown in fig. 2 includes the following steps:

1) the solid-state microwave source outputs power with certain frequency and magnitude to the receiving antenna through the transmitting horn. The solid microwave source is a microwave solid source or a plurality of microwave solid frequency sources with broadband or working at a plurality of frequency points.

2) The receiving antenna (or receiving loudspeaker) receives the signal, then detects and amplifies the signal, further carries out analog-digital conversion and sampling, and then feedback power can be obtained, and the power and the frequency are sent to the transmitting loudspeaker through the broadband microwave solid-state amplifier.

As shown in fig. 3, which is a working timing diagram of the present embodiment, the working timing specifically includes:

(1) the heated object is placed on a food table, and the solid-state microwave source outputs a small-power signal with a certain frequency. The solid microwave source is a microwave solid source or a plurality of microwave solid frequency sources with broadband or working at a plurality of frequency points;

(2) after receiving the feedback power by a receiving antenna (or receiving a loudspeaker), carrying out digital processing comprising the steps of detection amplification, analog-digital conversion, sampling and the like, and then storing the obtained power;

(3) and (3) adjusting the output frequency of the solid microwave source, and repeating the step (1) and the step (2) until all frequency points are finished. Comparing the stored power, selecting the frequency corresponding to the minimum value of the feedback power, further selecting the frequency as the output frequency of the solid-state microwave source, and increasing the output power through a broadband microwave solid-state amplifier for heating;

(4) in the heating process, continuously repeating the step (1), the step (2) and the step (3), thereby ensuring that the frequency with the minimum feedback power is always used as the output power of the solid-state microwave source, and further realizing high-efficiency heating;

(5) and after heating is finished, closing the heating device.

The method comprises the steps of transmitting power with certain frequency and certain magnitude in advance in the heating process, comparing the power magnitude by receiving the magnitude of the reflected power, selecting the frequency corresponding to the minimum value of the power, and finally realizing the specific working frequency by adjusting the power and the frequency.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. An intelligent frequency selection method for a microwave oven based on a solid-state source is characterized by comprising the following steps:

1) the solid-state microwave source outputs set frequency and power to the feedback device;

2. The intelligent frequency selection method for the solid-state source based microwave oven according to claim 1, wherein the feedback device in step 1) comprises a directional coupler, a power divider or a microwave energy receiving antenna built in the microwave oven.

3. The method according to claim 1, wherein the step 2) is specifically to compare all or part of the reflected power received by the feedback device after the reflected power is amplified by detection, converted and sampled by analog and digital signals, and by using an fpga (field Programmable Gate array) or a DSP system, determine which frequency point or band has the smallest reflected power, and heat the frequency point or band.

4. The intelligent frequency selection method for the solid-state source-based microwave oven according to claim 1, wherein the solid-state microwave source is a microwave solid-state source or a plurality of microwave solid-state frequency sources which work in a broadband or a plurality of frequency points.

5. The intelligent frequency selection method for a solid state source based microwave oven according to claim 1, wherein the solid state microwave source is capable of adjusting output power by adjustment of an external circuit.