CN108566697B

CN108566697B - Control method and microwave cooking appliance

Info

Publication number: CN108566697B
Application number: CN201810320816.0A
Authority: CN
Inventors: 庄耿; 刘存
Original assignee: Midea Group Co Ltd; Guangdong Midea Kitchen Appliances Manufacturing Co Ltd
Current assignee: Guangdong Witol Vacuum Electronic Manufacture Co Ltd
Priority date: 2018-04-11
Filing date: 2018-04-11
Publication date: 2021-03-19
Anticipated expiration: 2038-04-11
Also published as: CN108566697A

Abstract

The invention discloses a control method and a microwave cooking appliance. The auxiliary load is connected with the frequency converter in parallel, the switch is connected with a circuit formed by connecting the frequency converter and the auxiliary load in parallel, and the frequency converter is connected with the microwave generator. The control method comprises the following steps: controlling the switch part to be closed according to the control instruction so as to enable the frequency converter, the microwave generator and the auxiliary load to work simultaneously; and after the microwave generator works for a first time period, controlling the frequency converter to stop working the microwave generator when the switch piece is kept closed and the auxiliary load works. In the control method and the microwave cooking appliance, the microwave generator and the auxiliary load share one switch piece, the microwave generator belongs to a large load, and the connected switch piece has strong anti-impact current capability, so that the cost can be saved, the market reject ratio and the maintenance cost can be reduced, and the competitiveness of the product can be improved.

Description

Control method and microwave cooking appliance

Technical Field

The invention relates to the technical field of household appliances, in particular to a control method and a microwave cooking appliance.

Background

In the related art, a microwave oven product controls a load operation through a relay, and generally, a microwave generator and a small load such as a fan, a turntable, and a lamp are individually controlled by two different relays, respectively. However, since a relay for controlling a small load such as a fan, a turntable, and a furnace lamp is not high in impact resistance against current, there may occur a problem of sticking of a contact of the relay in an environment where a load is abnormal and a manufacturing factor affects. Meanwhile, a certain proportion of relay contact adhesion exists in poor feedback of the market.

Disclosure of Invention

The invention provides a control method and a microwave cooking appliance.

The control method of the embodiment of the invention is used for microwave cooking equipment, the microwave cooking appliance comprises a microwave generator, a frequency converter, an auxiliary load and a switch piece, the auxiliary load is connected with the frequency converter in parallel, the switch piece is connected on a circuit formed by connecting the frequency converter and the auxiliary load in parallel, the frequency converter is connected with the microwave generator, and the control method comprises the following steps:

controlling the switch piece to be closed according to a control command so as to enable the frequency converter, the microwave generator and the auxiliary load to work simultaneously; and

and after the microwave generator works for a first time, controlling the frequency converter to stop working when the switching piece is kept closed and the auxiliary load works.

In some embodiments, the control method further comprises: and after the frequency converter stops working for a second time, controlling the switch part to be switched off, and stopping the auxiliary load.

In some embodiments, the microwave cooking appliance further comprises an electronic control board provided with an input device that generates the control instructions.

In some embodiments, the frequency converter includes a switching tube and a transformer, the switching tube is connected to a primary side of the transformer, the microwave generator is connected to a secondary side of the transformer, and the step of controlling the frequency converter to stop operating includes:

and controlling the switching tube to be switched off, and stopping the frequency converter.

The microwave cooking appliance comprises a frequency converter, a microwave generator, an auxiliary load, a switch piece and a control module, wherein the auxiliary load is connected with the frequency converter in parallel, the switch piece is connected on a circuit formed by connecting the frequency converter and the auxiliary load in parallel, the control module is connected with the switch piece and the frequency converter, the frequency converter is connected with the microwave generator, and the control module is used for:

In certain embodiments, the control module is further configured to:

and after the frequency converter stops working for a second time, controlling the switch part to be switched off, and stopping the auxiliary load.

In some embodiments, the frequency converter includes a switching tube and a transformer, the switching tube is connected to a primary side of the transformer, the microwave generator is connected to a secondary side of the transformer, the control module is configured to control the switching tube to be turned on and off, when the switching tube is turned on, the frequency converter and the microwave generator operate, and when the switching tube is turned off, the frequency converter and the microwave generator stop operating.

In certain embodiments, the auxiliary load comprises at least one of a fan, a turntable, and a furnace light.

The microwave cooking electric appliance comprises a frequency converter, a microwave generator, an auxiliary load, a switch piece and an electric control board, wherein the auxiliary load is connected with the frequency converter in parallel, the switch piece is connected on a circuit formed by connecting the frequency converter and the auxiliary load in parallel, the electric control board is connected with the switch piece and the frequency converter, and the frequency converter is connected with the microwave generator.

In some embodiments, the frequency converter comprises a switch tube and a transformer, the switch tube is connected to a primary side of the transformer, the microwave generator is connected to a secondary side of the transformer, and the electric control board is connected to the switch tube.

In the control method and the microwave cooking appliance of the embodiment of the invention, the auxiliary load is connected with the frequency converter in parallel, the closing of the switch piece can control the frequency converter, the microwave generator and the auxiliary load to work simultaneously, and the microwave generator and the auxiliary load share one switch piece for control. The frequency converter can be controlled to stop working under the condition that the switch piece is kept closed, so that the microwave generator stops working and the auxiliary load keeps working continuously. Therefore, the microwave generator and the auxiliary load can share one switch piece, and the cost is saved. Meanwhile, as the switch part connected with the frequency converter has stronger anti-impact current capability, the market reject ratio and the maintenance cost can be reduced, and the competitive power of the product is improved.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic flow chart of a control method according to an embodiment of the present invention;

fig. 2 is a schematic circuit module diagram of a microwave cooking appliance according to an embodiment of the present invention;

FIG. 3 is a schematic flow chart of a control method of an embodiment of the present invention;

fig. 4 is a schematic view of another circuit module of the microwave cooking appliance according to the embodiment of the present invention;

fig. 5 is a circuit schematic of a frequency converter according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it should be noted that the terms "mounted," "connected," and "connected" are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected unless otherwise explicitly stated or limited. Either mechanically or electrically. Either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations. In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.

Referring to fig. 1 and 2, the embodiment of the invention provides a control method for a microwave cooking appliance 100, wherein the microwave cooking appliance 100 includes a microwave generator 10, a frequency converter 20, an auxiliary load 30 and a switch 40. The auxiliary load 30 is connected with the frequency converter 20 in parallel, the switch element 40 is connected on a circuit formed by connecting the frequency converter 20 and the auxiliary load 30 in parallel, the frequency converter 20 is connected with the microwave generator 10, and the control method comprises the following steps:

s01: controlling the switch member 40 to be closed according to the control command, so that the frequency converter 20, the microwave generator 10 and the auxiliary load 30 work simultaneously; and

s02: after the first period of operation of the microwave generator 10, the frequency converter 20 is controlled to stop operating to stop the operation of the microwave generator 10 while the switching member 40 is kept closed and the auxiliary load 30 is operated.

Referring to fig. 2, a microwave cooking appliance 100 according to an embodiment of the present invention is provided, and a control method according to an embodiment of the present invention may be used in the microwave cooking appliance 100 according to the present invention, where the microwave cooking appliance 100 includes a frequency converter 20, a microwave generator 10, an auxiliary load 30, a switching element 40, and a control module 50, the auxiliary load 30 is connected in parallel with the frequency converter 20, the switching element 40 is connected to a circuit formed by the frequency converter 20 and the auxiliary load 30 connected in parallel, the control module 50 is connected to the switching element 40 and the frequency converter 20, the frequency converter 20 is connected to the microwave generator 10, and steps S01 and S02 may be implemented by the control module 50, that is, when the control module 50 is used to control the switching element 40 to be closed according to a control instruction, so that the frequency converter 20, the microwave generator 10, and the auxiliary load 30 operate simultaneously, and after the microwave generator 10 operates for a first time, the switching element 40 is kept closed, the frequency converter 20 is controlled to stop operating to stop the operation of the microwave generator 10.

In the control method and the microwave cooking appliance 100, the auxiliary load 30 is connected in parallel with the frequency converter 20, and the frequency converter 20 is connected with the microwave generator 10, so that the on-off of the microwave generator 10 can be controlled. When the switch member 40 is closed, the frequency converter 20, the microwave generator 10 and the auxiliary load 30 all work at the same time, and the microwave generator 10 and the auxiliary load 30 are controlled by the switch member 40. And, the frequency converter 20 can be controlled to stop operating with the switch 40 kept closed to stop the operation of the microwave generator 10 and keep the auxiliary load 30 continuously operating. Thus, the microwave generator 10 and the auxiliary load 30 can share one switch member 40, and meanwhile, since the microwave generator 10 belongs to a large load, the connected switch member 40 has strong anti-impact current capability, thus not only saving the cost, but also reducing the market reject ratio and the maintenance cost and improving the competitiveness of the product.

Specifically, in one embodiment, the switching element 40 may be a solid state relay, such as the 16A solid state relay, which functions as short circuit protection, overload protection, and overheat protection in addition to being able to control the switching of the power supply. That is, when the microwave cooking appliance 100 is short-circuited, overloaded or overheated, the solid-state relay can timely cut off the circuit, so as to avoid causing a safety accident. It will be appreciated that the specific type and model of the switch member 40 can be selected according to the size of the microwave generator 10 and the auxiliary load 30, and is not particularly limited. The microwave generator 10 is used to generate microwave energy to heat food, and the frequency converter 20 is used to supply operating current to the microwave generator 10. In one example, the microwave generator 10 may be a magnetron, which may convert dc power into microwave oscillation power for output.

In addition, the auxiliary load 30 includes one or more of a fan, a turntable, and a furnace lamp. The fan is mainly used for radiating heat of the microwave cooking appliance 100, and safety accidents caused by overhigh temperature due to heat generated by the microwave cooking appliance 100 during working are prevented. The turntable is mainly used for bearing food, and when the microwave cooking appliance 100 works, the turntable can drive the food to rotate, so that the food is heated more uniformly. The oven lamp is used for providing illumination, so that a user can observe the condition of food when heating the food. Specifically, the auxiliary load 30 belongs to a small load, and in the embodiment, the auxiliary load 30 is connected in parallel with the frequency converter 20, so that an additional switch is not needed to be used for independently controlling the auxiliary load 30, and the production cost is saved.

In the embodiment shown in fig. 2, the auxiliary load 30 includes a fan 31, a turntable 32, and oven lights 33.

The first time period is an operating time period of the microwave generator 10, and the first time period is a heating time period set when the user uses the microwave cooking appliance 100. The first time period may be a default heating time period of the microwave cooking appliance 100 in a certain operation mode, or may be a heating time period set by a user.

Referring to fig. 3, in some embodiments, the control method further includes the steps of:

s03: after the second period of time when the frequency converter 20 stops operating, the control switch 40 is turned off and the auxiliary load 30 stops operating.

Referring to fig. 2, in some embodiments, step S03 may be implemented by the control module 50, that is, the control module 50 is configured to control the switching element 40 to open and the auxiliary load 30 to stop operating after the frequency converter 20 stops operating for the second duration.

Specifically, after the frequency converter 20 stops operating, the auxiliary load 30 is kept operating for a while, and the microwave cooking appliance 100 can be sufficiently cooled. In this way, the life of the components of the microwave cooking appliance 100 can be extended. Meanwhile, the food can have time to dissipate heat to a certain degree, so that the user can not scald hands when taking the food.

Generally, the second time period is a fixed time period set after the microwave cooking appliance 100 is tested before being shipped from a factory. It is understood that in some examples, the user may also set the second duration of the microwave cooking appliance 100 directly during use, and the second duration may be understood as a delay duration. In the example of fig. 1, after the microwave generator 10 stops working, the fan, the turntable, and the furnace lamp continue to blow air to dissipate heat until the second time elapses, and the switching member 40 is not turned off.

Referring to fig. 4, in some embodiments, the microwave cooking appliance 100 includes an electronic control board 60, and an input device 61 is disposed on the electronic control board 60, and the input device 61 can generate a control command according to an input of a user.

In this way, the user can input an instruction on the input device 61 to control the microwave cooking appliance 100 to implement a corresponding function. For example, a heating time period, a type of heating food, and heating power are inputted. In some examples, the input device 61 includes an adjustment knob that can be rotated by a user to set a desired heating time period and heating power, and a button that can be pressed to select a type of food to be heated. In other examples, the input device 61 may include a touch display panel, and the user may set the heating time period, the heating power, the type of food to be heated, and the like by touching the touch display panel.

In the illustrated embodiment, some or all of the functionality of the control module 50 may be integrated into the electronic control board 60. Of course, in other embodiments, the control module 50 may be provided separately from the electronic control board 60.

Referring to fig. 5, in some embodiments, the frequency converter 20 includes a switching tube 21 and a transformer 22, the transformer 22 includes a primary side and a secondary side, the switching tube 21 is connected to the primary side, and the microwave generator 10 is connected to the secondary side. Step S02 includes:

the control switch tube 21 is turned off, and the frequency converter 20 stops working.

In some embodiments, the above steps may be implemented by the control module 50, that is, the control module 50 may be configured to control the switching tube 21 to be turned off, so as to stop the operation of the frequency converter 20.

In this way, the microwave generator 10 can be deactivated without opening the switching element 40, while the auxiliary load 30 can continue to operate until the second period of time has elapsed.

Specifically, the switching tube 21 includes an Insulated Gate Bipolar Transistor (IGBT). The switch tube 21 is connected to the primary side of the transformer 22, and the switch tube 21 can control the working state of the frequency converter 22. Meanwhile, the switch tube 21 is further connected to the control module 50, and the control module 50 can generate a control signal to control the on/off of the switch tube 21. When the switching tube 21 is turned on, the frequency converter 20 is operated, and at this time, the microwave generator 10 connected to the frequency converter 20 is also operated at the same time, thereby generating microwaves. When the switching tube 21 is turned off, the frequency converter 20 and the microwave generator 10 stop operating.

In the example of fig. 5, the frequency converter 20 further includes a rectifying module 23, a filtering module 24, and a voltage-doubling rectifying module 25, where the rectifying module 23 is connected to the ac source 26 and the filtering module 24, and the switching tube 21 and the transformer 22 are connected to the filtering module 24. The voltage-doubling rectifying module 25 is connected to the secondary side of the transformer 22, and the voltage-doubling rectifying module 25 is used for increasing the output voltage of the transformer 22. In this way, the output voltage of the transformer 22 can be multiplied by the voltage-doubler rectifier module 25, and the circuit configuration is simple.

Referring to fig. 4, the microwave cooking appliance 100 according to the embodiment of the present invention includes a frequency converter 20, a microwave generator 10, an auxiliary load 30, a switching element 40, and an electric control board 60, wherein the auxiliary load 30 is connected in parallel with the frequency converter 20, the switching element 40 is connected to a circuit formed by the frequency converter 20 and the auxiliary load 30 connected in parallel, the electric control board 60 is connected with the switching element 40 and the frequency converter 20, and the frequency converter 20 is connected with the microwave generator 10.

Specifically, the electronic control board 60 is connected to the switch 40 and the frequency converter 20, and the electronic control board 60 can control the switch 40 to be closed according to a control instruction of a user, so that the frequency converter 20, the microwave generating gas and the auxiliary load 30 operate simultaneously, and after the first time period of operation, when the switch 40 is kept closed and the auxiliary load 30 operates, the frequency converter 20 is controlled to stop operating, so that the microwave generator 10 also stops operating. Then, after the frequency converter 20 stops working for a second time period, the electronic control board 60 controls the switch element 40 to be turned off, and the auxiliary load 30 stops working.

The first time period is a working time period set according to an input instruction of a user, and the second time period is a time delay period set before the microwave cooking appliance 100 leaves the factory or a time delay period set according to an input of the user.

In the above embodiment, the frequency converter 20 includes the switching tube 21 and the transformer 22, the transformer 22 includes the primary side and the secondary side, the switching tube 21 is connected to the primary side, the microwave generator 10 is connected to the secondary side, and the electronic control board 60 is connected to the switching tube 21.

Specifically, the switching tube 21 includes an Insulated Gate Bipolar Transistor (IGBT). The switch tube 21 is connected to the transformer 22, and the switch tube 21 can control the on/off of the transformer 22. Meanwhile, the switch tube 21 is further connected to the electronic control board 60, and the electronic control board 60 can generate a control signal to control the on/off of the switch tube 21. When the switching tube 21 is turned on, the transformer 22 is operated, and at this time, the microwave generator 10 connected to the secondary side of the transformer 22 is also operated at the same time, thereby generating microwaves. When the switching tube 21 is turned off, the transformer 22 and the microwave generator 10 stop operating.

In the description herein, references to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example" or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.

The logic and/or steps represented in the flowcharts or otherwise described herein, such as an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processing module-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection having one or more wires (control method), a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.

It should be understood that portions of embodiments of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.

It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.

In addition, functional units in the embodiments of the present invention may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.

The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A control method is used for a microwave cooking appliance, the microwave cooking appliance comprises a microwave generator, a frequency converter, an auxiliary load and a switch element, the auxiliary load is connected with the frequency converter in parallel, the switch element is connected on a circuit formed by connecting the frequency converter and the auxiliary load in parallel, the frequency converter is connected with the microwave generator, and the control method comprises the following steps:

after the microwave generator works for a first time, controlling the frequency converter to stop working when the switching piece is kept closed and the auxiliary load works;

the frequency converter comprises a switch tube and a transformer, the switch tube is connected to the primary side of the transformer, the microwave generator is connected to the secondary side of the transformer, and the step of controlling the frequency converter to stop working comprises the following steps:

2. The control method according to claim 1, characterized by further comprising: and after the frequency converter stops working for a second time, controlling the switch part to be switched off, and stopping the auxiliary load.

3. The control method according to claim 1, wherein the microwave cooking appliance further comprises an electronic control board provided with an input device that generates the control command.

4. The microwave cooking appliance is characterized by comprising a frequency converter, a microwave generator, an auxiliary load, a switch piece and a control module, wherein the auxiliary load is connected with the frequency converter in parallel, the switch piece is connected on a circuit formed by connecting the frequency converter with the auxiliary load in parallel, the control module is connected with the switch piece and the frequency converter, the frequency converter is connected with the microwave generator, and the control module is used for:

the frequency converter comprises a switch tube and a transformer, the switch tube is connected to the primary side of the transformer, the microwave generator is connected to the secondary side of the transformer, the control module is used for controlling the switch tube to be switched on and off, when the switch tube is switched on, the frequency converter works with the microwave generator, and when the switch tube is switched off, the frequency converter stops working with the microwave generator.

5. The microwave cooking appliance of claim 4 wherein the control module is further configured to:

6. The microwave cooking appliance of claim 4 wherein the auxiliary load includes at least one of a fan, a turntable, and an oven light.

7. A microwave cooking appliance is characterized by comprising a frequency converter, a microwave generator, an auxiliary load, a switch part and an electric control board, wherein the auxiliary load is connected with the frequency converter in parallel, the switch part is connected on a circuit formed by connecting the frequency converter and the auxiliary load in parallel, the electric control board is connected with the switch part and the frequency converter, the frequency converter is connected with the microwave generator, and the electric control board is used for controlling the switch part to be closed according to a control instruction so as to enable the frequency converter, the microwave generator and the auxiliary load to work simultaneously and controlling the frequency converter to stop working when the switch part is kept closed and the auxiliary load works after the microwave generator works for a first time; the frequency converter comprises a switch tube and a transformer, the switch tube is connected to the primary side of the transformer, the microwave generator is connected to the secondary side of the transformer, the electric control board is connected to the switch tube, the electric control board is further used for controlling the switch tube to be disconnected, and the frequency converter stops working.