An electrically agitated solid-state microwave heating device

Abstract

An electrically stirred solid-state microwave heating device comprises a solid-state microwave source, which generates microwaves radiated into a heating cavity or a heating space through an antenna array, an antenna cover is arranged between the antenna array and the heating cavity or the heating space, a metal heat sink is attached to the side of the solid-state microwave source away from the antenna cover, and a heat dissipation air duct is further arranged between the solid-state microwave source and the metal heat sink; the solid-state microwave source generates multiple paths of microwave signals with adjustable frequency, amplitude and phase, and feeds them into the antenna array, the electromagnetic energy of multiple branches is synthesized in space, different radiation states are generated according to control signals, and the heating effect of electric stirring is realized; the metal heat sink and the heat dissipation air duct can promptly dissipate the heat generated by the solid-state microwave source; the electromagnetic energy radiated by the antenna array passes through the antenna cover, and the antenna cover can also encapsulate the antenna array; the device has the characteristics of uniform heating, good heat dissipation, compact structure and high cleanliness.

Description

Technical Field

[0001] This invention relates to the field of microwave heating technology, and in particular to a solid-state microwave heating device with electric stirring. Background Technology

[0002] Microwave heating is a method of heating objects using electromagnetic fields. Microwaves can penetrate objects and generate a thermal effect inside them, heating the objects evenly and avoiding the problems of the surface being easily burned and the inside being uncooked, which are common in traditional heating methods. It has wide applications in household and industrial heating.

[0003] In current common microwave heating systems, magnetrons are often used as microwave energy generators. Energy is coupled into a waveguide and then fed into a metal cavity to heat objects inside. Magnetrons are bulky vacuum devices, occupying considerable space and requiring a high-voltage power supply with demanding heat dissipation requirements. With the development of high-power semiconductor devices such as GaN, solid-state microwave circuits, due to their small size, long lifespan, ease of control, and lack of high-voltage power supply, have replaced traditional magnetrons in many fields. For example, in radar systems, solid-state microwave sources are now widely used instead of magnetron feeds. Using solid-state microwave sources as feeds for heating systems is an important future development direction.

[0004] According to electromagnetic field theory, the electromagnetic field within a metal cavity has a fixed resonant mode, resulting in an uneven distribution of the electromagnetic field in space, which is detrimental to uniform heating. Therefore, most current household microwave heating systems employ mechanical stirring. One method involves placing the food on a turntable, allowing it to heat evenly during rotation. However, this method requires a large cavity space, and oil residue generated during heating can easily leak into the microwave feed port, making cleaning difficult. Another mechanical stirring method places the stirrer under a glass partition containing the food, improving heating uniformity by altering the resonant distribution of the electromagnetic field within the cavity. However, this method still suffers from drawbacks such as large size and a tendency to ignite. Using multiple feed sources is another way to improve the uniformity of the electromagnetic field within the cavity, but due to the lack of active stirring, the heating uniformity of this method is not ideal.

[0005] Wang Zhuangfei (Wang Zhuangfei, Xu Dongyuan, Huang Jie, et al. Application of frequency conversion phase modulation power divider network in microwave directional heating [J]. Vacuum Electronics Technology, 2022, (02): 77-81. DOI: 10.16540 / j.cnki.cn11-2485 / tn.2022.02.12.) proposed a microwave directional heating method based on frequency conversion phase modulation power divider network. By changing the frequency of the solid-state microwave source, the phase of the radiating antenna element is indirectly changed, thereby changing the direction of radiated energy. It has achieved good heating and stirring effect in a cavity three-zone heating system. However, this method can only control the frequency of the solid-state microwave source, and the control mode is limited. It has limited control capability for multi-antenna systems. At the same time, due to the large power of a single solid-state microwave source and the inconsistency of phase on the power divider network, there will be a large power loss on the isolation resistor. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention aims to provide an electrically stirred solid-state microwave heating device. This device generates multiple microwave signals with adjustable frequency, amplitude, and phase through a solid-state microwave source and feeds them into an antenna array. The electromagnetic energy of multiple branches is synthesized in space, generating different radiation states according to control signals to achieve the heating effect of electrical stirring. A metal heat sink and heat dissipation ducts can dissipate the heat generated by the solid-state microwave source in a timely manner. The electromagnetic energy radiated by the antenna array passes through the antenna cover, which also encapsulates the antenna array. This device features uniform heating, good heat dissipation, compact structure, and high cleanliness, and can be widely applied in microwave heating and other technical fields.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A solid-state microwave heating device for electric stirring includes a solid-state microwave source 3. The solid-state microwave source 3 generates microwaves that are radiated into a heating cavity or heating space through an antenna array 2. An antenna cover 1 is provided between the antenna array 2 and the heating cavity or heating space. A metal heat sink 5 is attached to the side of the solid-state microwave source 3 away from the antenna cover 1. A heat dissipation duct 4 is also provided between the solid-state microwave source 3 and the metal heat sink 5.

[0009] Furthermore, the antenna array 2 includes an antenna element 21, a feed probe 22, and an antenna ground plane 23; the feed probe 22 passes through the antenna ground plane 23 and is connected to the antenna element 21; the antenna element 21 is connected to the solid-state microwave source 3 through the feed probe 22.

[0010] Furthermore, the solid-state microwave source 3 includes a frequency synthesizer module 31, a power supply network module 32, multiple solid-state power amplifier modules 33, and a control circuit 34; the signal output terminal of the frequency synthesizer module 31 is connected to the signal input terminal of the power supply network module 32, the signal output terminal of the power supply network module 32 is connected to the signal input terminals of the multiple solid-state power amplifier modules 33 respectively, and the control circuit 34 is connected to the frequency synthesizer module 31, the power supply network module 32, and the multiple solid-state power amplifier modules 33 respectively.

[0011] Furthermore, the frequency synthesis module 31 includes an integrated phase-locked loop chip 311 and a preliminary amplifier circuit 312; the signal output terminal of the integrated phase-locked loop chip 311 is connected to the signal input terminal of the preliminary amplifier circuit 312.

[0012] The power supply network module 32 includes a power divider 321 and multiple phase shifters 322; the signal output terminal of the preliminary amplifier circuit 312 is connected to the signal input terminal of the power divider 321, and the signal output terminal of the power divider 321 is connected to the signal input terminals of the multiple phase shifters 322 respectively.

[0013] The solid-state power amplifier module 33 includes an adjustable attenuator 331, a first-stage power amplifier 332, and a second-stage power amplifier 333; the signal output terminal of the phase shifter 322 is connected to the signal input terminal of the adjustable attenuator 331, the signal output terminal of the adjustable attenuator 331 is connected to the signal input terminal of the first-stage power amplifier 332, and the signal output terminal of the first-stage power amplifier 332 is connected to the signal input terminal of the second-stage power amplifier 333.

[0014] The control circuit 34 is connected to the integrated phase-locked loop chip 311, multiple phase shifters 322 and multiple adjustable attenuators 331 respectively.

[0015] Furthermore, the antenna array 2 employs multiple antenna elements 21 arranged in a phased array manner, including but not limited to linear array, planar array, or curved array arrangements.

[0016] Furthermore, the antenna element 21 adopts a patch antenna or a suspended antenna, with an operating frequency band of 2400-2500MHz.

[0017] Furthermore, the input reflection coefficient of the antenna array 2 is less than -10dB within the operating frequency band.

[0018] Furthermore, the control circuit 34 includes a microcontroller for controlling the operating state of the solid-state microwave source 3.

[0019] Furthermore, the primary power amplifier 332 and the secondary power amplifier 333 are constructed using semiconductor devices; the semiconductor devices include, but are not limited to, GaN semiconductor devices.

[0020] Furthermore, the antenna array 2 and the solid-state microwave source 3 are integrated into one unit using PCB technology.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. This invention uses a solid-state microwave source 3 instead of a traditional magnetron feed source. Under the premise of multi-channel energy input, the state of energy in different channels is controlled by circuitry to synthesize different electromagnetic field distributions in the heating cavity or heating space to achieve electric stirring. This not only improves heating uniformity but also reduces the size of the equipment, thereby increasing the service life of the equipment. In addition, by replacing a single magnetron with multiple solid-state power amplifier modules 33 and replacing a large heat source with multiple small heat sources, distributed heat dissipation can be achieved, reducing the heat dissipation pressure.

[0023] 2. This invention combines multiple antenna arrays 2 and multiple solid-state microwave sources 3 to replace traditional mechanical stirring. By controlling the amplitude, phase and frequency of microwave energy through the control circuit 34, the radiation energy state can be changed, which can realize microwave heating and electric stirring, reducing the problems of sparking and oil stain cleaning.

[0024] 3. The antenna array 2 and the solid-state microwave source 3 can be integrated into one unit. The entire board can be realized using mature PCB technology, resulting in a compact structure that significantly reduces the size and weight of the entire system and facilitates disassembly and replacement.

[0025] In summary, this invention applies phased array antenna scanning technology to microwave heating. A solid-state microwave source 3 generates multiple microwave signals with adjustable frequency, amplitude, and phase, which are then fed into the antenna array 2. The electromagnetic energy of multiple branches is synthesized in space, generating different radiation states according to the control signal, achieving an electrically stirred heating effect. Compared to traditional mechanical stirring, this improves heating uniformity while avoiding problems such as arcing. By designing a metal heat sink 5 and a heat dissipation duct 4, the heat generated by the loss of the solid-state microwave source 3 can be dissipated in a timely manner. Furthermore, the distributed operation of multiple solid-state power amplifier modules 33 reduces the heat dissipation pressure on individual tubes, making this invention widely applicable in microwave heating and other technical fields. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the solid-state microwave heating device with electric stirring according to the present invention.

[0027] Figure 2 This is an external view of the antenna array 2 in this invention.

[0028] Figure 3 This is a schematic diagram of the solid-state microwave source 3 in this invention.

[0029] Figure 4 This is the first radiation gain state of antenna array 2 in this invention.

[0030] Figure 5 This is the second radiation gain state of antenna array 2 in this invention.

[0031] Figure 6 This is the input reflection coefficient of antenna array 2 in this invention.

[0032] In the diagram: 1. Radome; 2. Antenna array; 21. Antenna element; 22. Feed probe; 23. Antenna ground plane; 3. Solid-state microwave source; 31. Frequency synthesizer module; 311. Integrated phase-locked loop chip; 312. Preliminary amplifier circuit; 32. Feed network module; 321. Power divider; 322. Phase shifter; 33. Solid-state power amplifier module; 331. Adjustable attenuator; 332. First-stage power amplifier; 333. Second-stage power amplifier; 34. Control circuit; 4. Heat dissipation duct; 5. Metal heat sink. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings.

[0034] See Figure 1 A solid-state microwave heating device for electric stirring includes a solid-state microwave source 3. The solid-state microwave source 3 generates microwaves that are radiated into a heating cavity or heating space through an antenna array 2. An antenna cover 1 is provided between the antenna array 2 and the heating cavity or heating space. A metal heat sink 5 is attached to the side of the solid-state microwave source 3 away from the antenna cover 1. A heat dissipation duct 4 is also provided between the solid-state microwave source 3 and the metal heat sink 5.

[0035] This embodiment aims to improve heating efficiency by replacing the traditional magnetron with a solid-state microwave source 3 and by replacing traditional mechanical stirring with electrical stirring. The solid-state microwave source 3 generates multiple microwave energies and modifies the amplitude, phase, and frequency of the energy fed into the antenna array 2 through its own control circuit 34. According to phased array antenna theory, the energy radiated by multiple antennas will be combined in the heating cavity or space, generating different microwave energy radiation directions and states, thereby achieving electrical stirring of the electromagnetic energy in the heating cavity or space. An antenna cover 1 is installed between the antenna array 2 and the heating cavity or space, allowing the electromagnetic energy radiated by the antenna array 2 to pass through the antenna cover 1 normally, while the antenna cover 1 also encapsulates the antenna array 2. The solid-state microwave source 3 is bonded to the metal heat sink 5 with thermal grease, allowing the heat from the solid-state microwave source to be promptly transferred to the metal heat sink 5. A heat dissipation duct 4 is provided between the solid-state microwave source 3 and the metal heat sink 5 to promptly remove the heat generated by the loss of the solid-state microwave source 3, thus achieving encapsulation and heat dissipation of the entire device.

[0036] like Figure 2The antenna array 2 includes an antenna element 21, a feed probe 22, and an antenna ground plane 23; the feed probe 22 passes through the antenna ground plane 23 and is connected to the antenna element 21; the antenna element 21 is connected to the solid-state microwave source 3 through the feed probe 22.

[0037] The antenna array 2 employs multiple antenna elements 21 arranged in a phased array manner, including but not limited to linear array, planar array, or curved array arrangements.

[0038] In this embodiment, the antenna element 21 is arranged in a 4*4 planar array, which can perform radiation scanning in two dimensions and effectively reduce the heat dissipation pressure of a single solid-state power amplifier module. The element spacing is 0.5 wavelengths, which is the normal phased array antenna element spacing (in order to avoid grating lobes, the spacing is generally less than or equal to 0.5 wavelengths). The feed probe 22 passes through the antenna ground plane 23 and feeds the antenna element 21. The solid-state microwave source 3 is connected to the antenna array 2 through the feed probe 22. The antenna array 2 radiates the microwaves generated by the solid-state microwave source 3 to the heating cavity or heating space, and performs electromagnetic energy synthesis in the space, thereby realizing the electric stirring of microwave heating.

[0039] The antenna element 21 adopts a patch antenna or a plate antenna, and selects the S-band with an operating frequency band of 2400-2500MHz.

[0040] like Figure 3 As shown, the solid-state microwave source 3 includes a frequency synthesizer module 31, a power supply network module 32, multiple solid-state power amplifier modules 33, and a control circuit 34. The signal output terminal of the frequency synthesizer module 31 is connected to the signal input terminal of the power supply network module 32, and the signal output terminal of the power supply network module 32 is connected to the signal input terminals of the multiple solid-state power amplifier modules 33. The control circuit 34 is connected to the frequency synthesizer module 31, the power supply network module 32, and the multiple solid-state power amplifier modules 33.

[0041] In this embodiment, the frequency synthesizer module 31 generates microwave energy and feeds it into the power supply network module 32. The power supply network module 32 divides the microwave energy into multiple microwave energy streams and feeds them into the solid-state power amplifier module 33. The solid-state power amplifier module 33 amplifies the multiple microwave energy streams. The control circuit 34 is connected to the frequency synthesizer module 31, the power supply network module 32, and the solid-state power amplifier module 33 respectively, and is used to control the working state of the entire solid-state microwave source 3.

[0042] The frequency synthesis module 31 includes an integrated phase-locked loop chip 311 and a preliminary amplification circuit 312; the signal output terminal of the integrated phase-locked loop chip 311 is connected to the signal input terminal of the preliminary amplification circuit 312; the integrated phase-locked loop chip 311 generates microwave energy according to the signal sent by the control circuit 34, and the preliminary amplification circuit 312 amplifies the microwave energy.

[0043] The power supply network module 32 includes a power divider 321 and multiple phase shifters 322; the signal output terminal of the preliminary amplifier circuit 312 is connected to the signal input terminal of the power divider 321, and the signal output terminal of the power divider 321 is connected to the signal input terminals of the multiple phase shifters 322 respectively.

[0044] The power divider 321 in this embodiment is a 1-to-16 power divider. The type of power divider 321 includes, but is not limited to, Wilkinson power dividers, Gysel power dividers, and T-type power dividers. The branch structure of the power divider 321 includes, but is not limited to, equal-division and unequal-division structures. A 1-to-2 or 1-to-multiple-path structure can be used as the branch structure of the power divider 321 in this embodiment. The wiring form of the power divider 321 includes, but is not limited to, microstrip lines, strip lines, and grounded coplanar waveguides. After receiving the microwave energy initially amplified by the preliminary amplification circuit 312, the power divider 321 divides the input single-path microwave energy into 16 paths. The phase of the 16 paths of microwave energy is changed by the phase shifter 322 added to the end of each branch of the power divider 321.

[0045] The solid-state power amplifier module 33 includes an adjustable attenuator 331, a first-stage power amplifier 332, and a second-stage power amplifier 333; the signal output terminal of the phase shifter 322 is connected to the signal input terminal of the adjustable attenuator 331, the signal output terminal of the adjustable attenuator 331 is connected to the signal input terminal of the first-stage power amplifier 332, and the signal output terminal of the first-stage power amplifier 332 is connected to the signal input terminal of the second-stage power amplifier 333.

[0046] The solid-state power amplifier module 33 in this embodiment includes two-stage power amplifiers and an adjustable attenuator 331. After receiving the microwave signal with a changed phase, the adjustable attenuator 331 adjusts the output power of the microwave signal according to the signal sent by the control circuit 34, and transmits it to the first-stage power amplifier 332 and the second-stage power amplifier 333 in sequence to further amplify the microwave signal.

[0047] The control circuit 34 is connected to the integrated phase-locked loop chip 311, multiple phase shifters 322, and adjustable attenuator 331 via phase signals. The control circuit 34 is connected to the integrated phase-locked loop chip 311 to control the frequency and power of the main output signal; it is also connected to the phase shifters 322 to control the phase of the microwave energy in each branch; and finally, it is connected to the adjustable attenuator 331 to control the amplitude of the microwave energy in each branch.

[0048] The control circuit 34 includes a microcontroller for controlling the operating state of the solid-state microwave source 3. The control signal lines of the microcontroller are connected to the control pins of the integrated phase-locked loop chip 311, phase shifter 322, and adjustable attenuator 331 inside the solid-state microwave source 3, and the operating state of the chip is controlled using a serial communication protocol.

[0049] The primary power amplifier 332 and the secondary power amplifier 333 are constructed using semiconductor devices; the semiconductor devices include, but are not limited to, GaN semiconductor devices, LDMOS semiconductor devices, GaAs semiconductor devices, and SiGe semiconductor devices, all of which can be used as semiconductor devices in this embodiment.

[0050] The antenna array 2 and the solid-state microwave source 3 are integrated into one unit using PCB technology, resulting in a compact structure that significantly reduces the size and weight of the entire system and facilitates disassembly and replacement.

[0051] In order to control the amplitude, phase, and frequency of the radiated energy fed into each antenna, two different radiation states are synthesized in space. Figure 4 In radiation gain state one, the maximum radiation direction is located in the direction normal to the antenna array; Figure 5 In radiation gain state two, the maximum radiation direction is located below the normal, and the electromagnetic field distribution of the heating cavity or space changes, realizing the change of the heating area according to the control signal.

[0052] like Figure 6 As shown, the input reflection coefficient of the antenna array 2 is less than -10dB in the operating frequency band, which allows most of the electromagnetic energy to be radiated into the heating cavity or space, thus meeting the normal operating requirements of the entire heating device.

[0053] The working principle of this invention is:

[0054] Phased array antenna scanning technology is applied to microwave heating. First, a solid-state microwave source 3 generates multiple microwave signals with adjustable frequency, amplitude, and phase, which are then fed into the antenna array 2. The electromagnetic energy of multiple branches is synthesized in space, and different radiation states are generated according to the control signal to achieve the heating effect of electric stirring. An antenna cover 1 is installed between the antenna array 2 and the heating cavity or heating space. The electromagnetic energy radiated by the antenna array 2 can pass through the antenna cover 1 normally, and the antenna cover 1 can encapsulate the antenna array 2. By designing a metal heat sink 5 and a heat dissipation duct 4, the heat generated by the loss of the solid-state microwave source 3 is dissipated in time. At the same time, multiple solid-state power amplifier modules 33 are distributed to reduce the heat dissipation pressure of a single tube.

[0055] The above embodiments are merely detailed descriptions of the present invention, but the present invention is not limited to the above embodiments. Any modifications, substitutions, and changes made to the present invention within the spirit and scope of the claims are within the scope of protection of the present invention.

Claims

1. A solid-state microwave heating device with electric stirring, characterized in that: The system includes a solid-state microwave source (3), which generates microwaves that are radiated into a heating cavity or heating space through an antenna array (2). An antenna radome (1) is provided between the antenna array (2) and the heating cavity or heating space. A metal heat sink (5) is attached to the side of the solid-state microwave source (3) away from the antenna radome (1). A heat dissipation duct (4) is also provided between the solid-state microwave source (3) and the metal heat sink (5). The antenna array (2) and the solid-state microwave source (3) are integrated into one unit using PCB technology. The solid-state microwave source (3) includes a frequency synthesis module (31), a power supply network module (32), multiple solid-state power amplifier modules (33), and a control circuit (34). The control circuit (34) independently controls the amplitude, phase, and frequency of the output signal of each solid-state power amplifier module (33), so that the antenna array (2) generates different radiation states to achieve electric stirring heating. The frequency synthesis module (31) includes an integrated phase-locked loop chip (311) and a preliminary amplifier circuit (312); the signal output terminal of the integrated phase-locked loop chip (311) is connected to the signal input terminal of the preliminary amplifier circuit (312); The power supply network module (32) includes a power divider (321) and multiple phase shifters (322); the signal output terminal of the preliminary amplifier circuit (312) is connected to the signal input terminal of the power divider (321), and the signal output terminal of the power divider (321) is connected to the signal input terminals of the multiple phase shifters (322) respectively. The solid-state power amplifier module (33) includes an adjustable attenuator (331), a first-stage power amplifier (332), and a second-stage power amplifier (333); the signal output terminal of the phase shifter (322) is connected to the signal input terminal of the adjustable attenuator (331), the signal output terminal of the adjustable attenuator (331) is connected to the signal input terminal of the first-stage power amplifier (332), and the signal output terminal of the first-stage power amplifier (332) is connected to the signal input terminal of the second-stage power amplifier (333); The control circuit (34) is connected to the integrated phase-locked loop chip (311), multiple phase shifters (322) and multiple adjustable attenuators (331) respectively. It controls the frequency and power of the main signal output by the integrated phase-locked loop chip (311), controls the phase shifter (322) corresponding to each branch and adjusts the phase of the microwave energy of that branch, controls the adjustable attenuator (331) corresponding to each branch and adjusts the amplitude of the microwave energy of that branch, so that the electromagnetic energy radiated by the multiple antenna elements (21) of the antenna array (2) is dynamically synthesized in the heating cavity or heating space to form different radiation directions and energy distributions, so as to realize electric stirring.

2. The solid-state microwave heating device with electric stirring according to claim 1, characterized in that: The antenna array (2) includes an antenna element (21), a feed probe (22), and an antenna ground plane (23); the feed probe (22) passes through the antenna ground plane (23) and is connected to the antenna element (21); the antenna element (21) is connected to the solid-state microwave source (3) through the feed probe (22).

3. The solid-state microwave heating device with electric stirring according to claim 1, characterized in that: The signal output terminal of the frequency synthesizer module (31) is connected to the signal input terminal of the power supply network module (32), and the signal output terminal of the power supply network module (32) is connected to the signal input terminals of multiple solid-state power amplifier modules (33). The control circuit (34) is connected to the frequency synthesizer module (31), the power supply network module (32), and the multiple solid-state power amplifier modules (33) respectively.

4. The solid-state microwave heating device with electric stirring according to claim 2, characterized in that: The antenna array (2) uses multiple antenna elements (21) arranged in a phased array manner. The phased array arrangement includes linear array, planar array or curved array.

5. The solid-state microwave heating device with electric stirring according to claim 4, characterized in that: The antenna unit (21) adopts a patch antenna or a suspension antenna, with a working frequency band of 2400-2500MHz.

6. The solid-state microwave heating device with electric stirring according to claim 1, characterized in that: The input reflection coefficient of the antenna array (2) is less than -10dB within the operating frequency band.

7. The solid-state microwave heating device with electric stirring according to claim 1, characterized in that: The control circuit (34) includes a microcontroller for controlling the working state of the solid-state microwave source (3).

8. The solid-state microwave heating device with electric stirring according to claim 1, characterized in that: The primary power amplifier (332) and the secondary power amplifier (333) are constructed using semiconductor devices; the semiconductor devices are GaN semiconductor devices.

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