CN-121772064-B - Multi-feed-source coaxial-waveguide composite resonance microwave heating device and control method

CN121772064BCN 121772064 BCN121772064 BCN 121772064BCN-121772064-B

Abstract

The invention discloses a multi-feed-source coaxial-waveguide composite resonance microwave heating device and a control method, wherein the device comprises a waveguide cavity and a plurality of coaxial coupling structures, the top surface of the waveguide cavity is open, the coaxial coupling structures are integrated in the cavity wall of the waveguide cavity, each coaxial coupling structure comprises a coaxial port and a coaxial coupling screw which are mutually connected, the coaxial port is used as an input end of a feed source, microwave signals are sequentially input into the waveguide cavity through the coaxial port and the coaxial coupling screw to heat an object to be heated in the waveguide cavity, and the embedded spiral structure is arranged to construct a composite resonance mode of a coaxial and waveguide, and the impedance matching and heating uniformity are further optimized by combining a gradual change spiral parameter design and a multi-source heating control method.

Inventors

LI JIACHEN
LIN PEIYING
DING WEI
QIN HAITING
FANG XIANG

Assignees

江苏科技大学苏州理工学院

Dates

Publication Date: 20260512
Application Date: 20260303

Claims (10)

1. The coaxial-waveguide composite resonance microwave heating device with multiple feeds is characterized by comprising a waveguide cavity and a plurality of coaxial coupling structures, wherein the top surface of the waveguide cavity is open, the coaxial coupling structures are integrated in the cavity wall of the waveguide cavity, each coaxial coupling structure comprises a coaxial port and a coaxial coupling screw which are mutually connected, the coaxial port is used as an input end of the feed, microwave signals are sequentially input into the waveguide cavity through the coaxial port and the coaxial coupling screw to heat an object to be heated in the waveguide cavity, The coaxial port is inserted into the cavity wall of the waveguide cavity along one axial direction, the other end of the coaxial port extends out of the waveguide cavity, the coaxial port comprises a port coaxial core and a port outer conductor, the port outer conductor is sleeved on the outer side of the port coaxial core and is arranged on the coaxial core, and an insulating medium is filled between the port outer conductor and the port coaxial core; The coaxial coupling screw comprises a screw groove recessed on the inner wall of the waveguide cavity and a screw coaxial core suspended in the screw groove, insulating medium is not filled between the screw coaxial core and the screw groove, the groove surface of the screw groove is a metal surface, and the screw coaxial core is electrically connected with a port coaxial core in the coaxial port and is used for transmitting microwave signals.
2. The multi-feed coaxial-waveguide composite resonant microwave heating device according to claim 1, wherein the coaxial coupling screw is a uniform screw or a non-uniform screw, and the pitch between adjacent screw threads on the screw coaxial core and the depth of the screw groove are both constant when the coaxial coupling screw is a uniform screw, and the pitch between adjacent screw threads on the screw coaxial core and the depth of the screw groove are both non-constant when the coaxial coupling screw is a non-uniform screw.
3. A multi-feed coaxial-waveguide composite resonant microwave heating device in accordance with claim 2, wherein the coaxial coupling helix satisfies the following physical relationship: , Wherein Z0 represents the characteristic impedance of the coaxial coupling screw, P represents the pitch of the screw coaxial core, D represents the diameter of the screw coaxial core, mu 0 represents the vacuum permeability, epsilon represents the dielectric constant of the medium between the screw groove and the screw coaxial core, and D represents the depth of the screw groove.
4. The multi-feed coaxial-waveguide composite resonant microwave heating device of claim 2, wherein when the coaxial coupling helix is a non-uniform helix, the pitch of the helical coaxial core is such that the pitch at the end proximal to the coaxial port is greater than the pitch at the end distal from the coaxial port.
5. The multi-feed coaxial-waveguide composite resonant microwave heating device of claim 2, wherein when the coaxial coupling helix is a non-uniform helix, the depth of the helical groove varies in gradient along the direction of helix extension, i.e., the depth of the helical groove increases in gradient from the coaxial port to the end of the helix.
6. The multi-feed coaxial-waveguide composite resonant microwave heating device of claim 1, wherein the coaxial ports in the plurality of coaxial coupling structures are uniformly spaced axially or circumferentially along the outer wall of the waveguide cavity, each coaxial port being connected to an independent phase and amplitude control channel.
7. The multi-feed coaxial-waveguide composite resonant microwave heating device of claim 1, wherein the system of transmitting radio frequency power sources for energizing the plurality of coaxial ports comprises a microwave excitation source, a power distribution network, a multi-channel phase control network, a distributed power amplification module, a distributed power matching network, a controller, and a DC power supply module, The microwave excitation source generates an initial radio frequency signal, is divided into a plurality of microwave signals through the power distribution network, and then enters a multichannel phase control network respectively; The multichannel phase control network comprises a plurality of independently adjustable phase shifting units, and the independently adjustable phase shifting units are used for independently modulating the phase of each path of microwave signal under the instruction of the controller; The distributed power amplification module comprises a plurality of power amplifiers which are in one-to-one correspondence with the coaxial ports and are used for receiving multipath signals subjected to phase modulation by the multichannel phase control network; The controller independently regulates and controls the output power amplitude of each path of microwave signals by regulating the direct-current bias voltage or drain voltage provided by the direct-current power supply module to each path of power amplifier, and the amplified multipath microwave signals are coupled into the waveguide cavity through the coaxial port after impedance matching through the distributed power matching network.
8. The multi-feed coaxial-waveguide composite resonant microwave heating device of claim 1, wherein the insulating medium is polyethylene, teflon or foamed plastic.
9. A microwave heating control method based on a multi-feed coaxial-waveguide composite resonance microwave heating device as claimed in any one of claims 1-8 is characterized in that the multi-feed coaxial-waveguide composite resonance microwave heating device has a partition independent heating mode and a multi-source cooperative heating mode, in particular, In the zone independent heating mode, a single or partial coaxial port is excited, and the corresponding coaxial coupling screw couples microwave energy to a set coverage area in the waveguide cavity, so that zone independent heating of the area in the waveguide cavity is realized; In the multi-source cooperative heating mode, all coaxial ports are excited simultaneously, and a controllable electromagnetic interference pattern is synthesized in a waveguide cavity by adjusting the relative phase and amplitude relation among the coaxial ports, and the method comprises the following specific steps of: 1) Initializing, starting a microwave excitation source, and generating a reference signal; 2) The phase scanning method comprises the steps of performing a rotating vector phase scanning strategy on the premise of maintaining the working frequency of a microwave signal constant, specifically setting one coaxial port as a reference phase, controlling the phases of the other coaxial ports to form a preset phase gradient sequence, periodically changing the integral offset of the phase gradient sequence or rotating the phase vector combination along with time, and exciting a rotating electromagnetic field mode in a waveguide cavity so as to enable an electric field interference peak area formed by superposition of multiple signals to perform traversing scanning in space; 3) And utilizing the coaxial coupling screw as the frequency dispersion characteristic of the slow wave structure, changing the axial angle and coverage range of microwave energy radiated from the screw structure into the waveguide cavity along with the change of frequency, and driving the radiation beam to dynamically scan in the longitudinal depth direction of the waveguide cavity.
10. The method for controlling microwave heating according to claim 9, wherein when the object to be heated is unevenly distributed or fixed-point heating is required, a zoned independent heating mode is adopted to increase the power amplitude of coaxial ports of the corresponding zone, and when the uniform heating of the whole cavity is required, a multi-source cooperative heating mode is adopted and steps 2) and 3) are cyclically executed, and the heating dead angle is reduced by utilizing multi-dimensional electromagnetic field scanning.

Description

Multi-feed-source coaxial-waveguide composite resonance microwave heating device and control method Technical Field The invention belongs to the technical field of microwave heating, and particularly relates to a coaxial-waveguide composite resonance microwave heating device with multiple feeds and a control method thereof. Background In recent years, the microwave heating technology has demonstrated great application potential in various industries, particularly in the fields of food processing, chemical treatment, medical preparation, tobacco production and the like. The microwave heating directly acts on the inside of the object through electromagnetic waves, so that heat can be transferred more efficiently and uniformly, the heating efficiency is greatly improved, and the energy consumption is reduced. In addition, the temperature can be precisely controlled by adjusting the frequency and the power in microwave heating, so that the heating requirements of different materials are met. Compared with the traditional mode, the microwave heating process is quicker, the energy efficiency is higher, the production efficiency can be improved, and the energy waste in production is reduced. Despite the wide application of microwave heating, the prior art solutions still face significant challenges in terms of precision control and uniformity, mainly in terms of: The current industrial microwave oven or early microwave heating equipment mainly relies on a magnetron as a microwave generator, and the output frequency is fixed and the phase is random and uncontrollable. When a plurality of magnetrons are operated simultaneously, chaotic and fixed standing wave interference patterns are formed in the cavity, so that obvious hot spots and cold spots are generated in the heated object. In industrial heating scenarios, such non-uniformities can lead to localized overheating damage to the material, low chemical reaction yields, or incomplete drying. The traditional resistance wire heating or electromagnetic induction heating mainly depends on heat conduction, and has the problems of long preheating time, low utilization rate of a central area and easy carbonization of burnt paste at the edge. In terms of coupling structure, existing microwave heating devices typically employ simple electric field probes or magnetic field loops for coupling. These conventional structures have difficulty in achieving impedance matching with high Q cavities over a wide frequency band, and particularly when the dielectric constant of the load varies drastically with temperature, the coupling efficiency may drop drastically, resulting in a large amount of energy reflection and even damage to the microwave source. In addition, the existing microwave heating technology lacks effective dynamic regulation means, and mechanical stirring is adopted in the prior art in order to improve heating uniformity. However, mechanical stirring can only improve the distribution on a time average, cannot eliminate transient strong spots, and cannot perform directional heating for a specific area. More importantly, conventional devices lack depth-wise control capability and cannot deliver differential energy based on the state differences of the object along the wave propagation direction. In summary, although microwave heating technology has great potential in improving heating efficiency and product quality, it still faces many challenges in terms of heating uniformity, multi-path cooperative control capability, energy efficiency, etc. Disclosure of Invention The invention aims to provide a coaxial-waveguide composite resonance microwave heating device with multiple feeds so as to improve heating uniformity and multi-channel cooperative control capability. The first object of the present invention is to provide a multi-feed coaxial-waveguide composite resonant microwave heating device, which comprises a waveguide cavity and a plurality of coaxial coupling structures, wherein the top surface of the waveguide cavity is open, the plurality of coaxial coupling structures are integrated in the cavity wall of the waveguide cavity, each coaxial coupling structure comprises a coaxial port and a coaxial coupling screw which are connected with each other, the coaxial port is used as the input end of the feed, microwave signals are sequentially input into the waveguide cavity through the coaxial port and the coaxial coupling screw to heat an object to be heated in the waveguide cavity, The coaxial port is inserted into the cavity wall of the waveguide cavity along one axial direction, the other end of the coaxial port extends out of the waveguide cavity, the coaxial port comprises a port coaxial core and a port outer conductor, the port outer conductor is sleeved on the outer side of the port coaxial core and is arranged on the coaxial core, and an insulating medium is filled between the port outer conductor and the port coaxial core; The coaxial coupling screw comprises