A plasma heater

Abstract

This invention discloses a plasma heater, comprising: a power supply system for converting mains power into controllable high-voltage direct current; and a multiphase discharge device electrically connected to the power supply system for generating a plasma jet. The power supply system includes a resonant inverter circuit based on zero-voltage switching. The multiphase discharge device includes a central common-ground electrode and multiple high-voltage electrodes arranged around it, forming a needle-needle discharge structure. This invention maintains the plasma arc column boundary temperature above 2000K by controlling the discharge current above 48mA, effectively suppressing nitrogen oxide generation and reducing NO2 emission concentration to below 6.5ppm, thus exhibiting efficient, stable, and environmentally friendly heating performance.

Description

Technical Field

[0001] This invention belongs to the technical field of household appliances and industrial heating equipment, and particularly relates to a plasma heater. Background Technology

[0002] Currently, household kitchens and small-scale industrial heating primarily rely on traditional gas stoves and induction cookers. Gas stoves use open flames for heating, offering advantages such as direct heat output, rapid heating, and excellent flavor. However, they depend on fossil fuels, producing harmful gases like carbon monoxide and nitrogen oxides during combustion, posing safety risks and environmental pollution. Induction cookers, on the other hand, are clean and safe, but their heating depends on the magnetic properties of the cookware, and the heating method can lead to uneven heating, resulting in sticking and poor cooking results. To address the shortcomings of these traditional heating methods, attempts have been made to utilize plasma technology for heating. Plasma, the fourth state of matter, is characterized by high energy density and strong chemical reactivity. Some studies have proposed the concept of an "electric flame stove," aiming to generate a plasma beam using an electric arc, combining the directness of open flame heating with the cleanliness of electric heating.

[0003] However, existing plasma heating technologies still have significant drawbacks: First, the discharge power and stability are insufficient. Most solutions are based on single-phase discharge, resulting in low-power, short-length plasma jets that are easily extinguished by electromagnetic interference, failing to meet the demands of high-temperature cooking such as stir-frying. Second, the electrode lifespan is short. The arc center temperature is extremely high, and traditional metal electrodes (such as pure copper) suffer severe ablation under high temperatures and ion bombardment, leading to short equipment lifespan and rapid performance degradation. Third, there is the issue of controlling harmful gases. The arc discharge in atmospheric pressure air ionizes nitrogen to generate byproducts such as nitrogen oxides, which, if not properly controlled, will bring new environmental and health hazards. Summary of the Invention

[0004] The purpose of this invention is to systematically overcome the multiple technical bottlenecks faced by existing plasma heating equipment in the process of industrialization, and to provide an innovative plasma electric heating heater. This equipment not only needs to be scientifically and rationally designed in terms of mechanical structure and circuit design, but also needs to achieve a high degree of stability and reliability in its working state. Through breakthroughs in materials science and dynamics, the service life of core components is significantly extended, and the overall energy conversion efficiency is improved through thermal management optimization. Ultimately, while ensuring strong heating performance, it fully meets the strict environmental emission standards of modern homes for clean energy equipment.

[0005] To solve the above-mentioned technical problems, the present invention provides a plasma heater, comprising: A power supply system used to convert mains power into controllable high-voltage direct current; A multiphase discharge device, electrically connected to the power supply system, is used to generate a plasma jet; Active discharge stability enhancement system; Closed-loop emission control system based on spectral diagnostics; The power supply system includes a resonant inverter circuit based on zero-voltage switching; The multiphase discharge device includes a central common ground electrode and multiple high-voltage electrodes arranged around it, forming a needle-needle discharge structure. The active discharge stability enhancement system includes: The plasma impedance spectrum online monitoring unit is used to acquire the dynamic complex impedance spectrum of each discharge channel in real time. A flow-electric field coordinated controller is used to synchronously adjust two actuators based on a dynamic complex impedance spectrum. First, control the phase difference of the output pulses of the power supply system to each discharge channel; Secondly, the opening of the multi-channel independent adjustable airflow valve integrated at the bottom of the discharge device is controlled to deliver customized airflow to each discharge gap, thereby actively suppressing channel sharing and arc extinction through the synergistic effect of airflow mechanics and electrical parameters. The closed-loop emission control system based on spectral diagnostics includes a fiber optic spectral probe and a spectral analyzer oriented towards the discharge region.

[0006] Preferably, the power supply system further includes a main power source and a boost module; The main power source is used to convert industrial frequency AC power into adjustable DC power; The resonant inverter circuit is connected to the main power source and is used to convert the direct current into high-frequency alternating current. The boost module includes multiple boost transformers connected in parallel, used to boost the high-frequency AC power to a high voltage.

[0007] Preferably, the resonant inverter circuit is an eight-phase parallel structure, comprising multiple independent resonant units; Each resonant unit drives a step-up transformer and supplies power to a corresponding high-voltage electrode.

[0008] Preferably, in the multiphase discharge device, the multiple high-voltage electrodes are arranged in a ring array; The axis of each high-voltage electrode is inclined upward relative to the horizontal plane, so that the discharge tip is spatially opposite to the tip of the central common-ground electrode.

[0009] Preferably, the central common ground electrode has a wolf-tooth-shaped structure with multiple discharge tips on its surface; The multiphase discharge device is also equipped with an isolation plate to reduce the phenomenon of shared discharge channels.

[0010] Preferably, the plasma heater further includes: An integrated heat dissipation and air intake system is located below the central common ground electrode; The integrated heat dissipation and air intake system includes heat dissipation components and a blower, used to cool the electrodes and supply air to the discharge area.

[0011] Preferably, the power supply system further includes an electromagnetic interference suppression structure; The electromagnetic interference suppression structure includes a discharge unit and a magnetic ring fitted onto the high-voltage output end of the step-up transformer. The discharge unit is independently grounded using a star grounding method.

[0012] Preferably, the power supply system controls the power of the plasma jet continuously or in stages by adjusting the input electrical parameters, thereby achieving adjustment from low power to high power.

[0013] Preferably, the high-voltage electrode is made of copper; The central common electrode is made of graphite.

[0014] Compared with the prior art, the present invention has the following advantages and technical effects: Compared with existing technologies, this invention achieves a high power output of up to 1800W and a plasma jet length of 220mm. The eight-phase parallel power supply and optimized electrode structure fundamentally solve the problems of low single-phase discharge power and easy arc extinction, achieving unprecedented stable heating performance. The innovative "copper high-voltage electrode-graphite common ground electrode" pairing scheme fully leverages the advantages of both materials, greatly enhancing the electrode assembly's resistance to electrical corrosion and its service life, thus solving the lifespan bottleneck of core consumable components. By precisely controlling the discharge current above 48mA, the plasma arc column boundary temperature is maintained above 2000K, successfully keeping the NO2 emission concentration stably controlled at an extremely low level below 6.5ppm, truly achieving a perfect balance between high efficiency, long lifespan, and clean environmental protection. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the multiphase generator circuit design according to an embodiment of the present invention. Detailed Implementation

[0016] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0017] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0018] This embodiment provides a plasma heater, including: A power supply system used to convert mains power into controllable high-voltage direct current; A multiphase discharge device, electrically connected to a power supply system, is used to generate plasma jets; The power supply system includes a resonant inverter circuit based on zero-voltage switching. The multiphase discharge device includes a central common ground electrode and multiple high-voltage electrodes arranged around it, forming a needle-needle discharge structure.

[0019] As an additional implementation, the plasma heater in this embodiment further includes: The active discharge stability enhancement system includes: The plasma impedance spectrum online monitoring unit is used to acquire the dynamic complex impedance spectrum of each discharge channel in real time. The flow-electric field coordinated controller synchronously adjusts two actuators based on the dynamic complex impedance spectrum. First, control the phase difference of the output pulses of the power supply system to each discharge channel; Secondly, the opening of the multi-channel independent adjustable airflow valve integrated at the bottom of the discharge device is controlled to deliver customized airflow to each discharge gap. In this way, through the synergistic effect of airflow mechanics and electrical parameters, channel sharing and arc extinction are actively suppressed, ensuring the spatial independence and temporal stability of the multi-beam plasma jet.

[0020] Specifically, the plasma impedance spectroscopy online monitoring unit operates as follows: Inject a high-frequency, small-signal disturbance current with controllable amplitude into each discharge channel; The disturbance voltage response of each channel is measured synchronously. The equivalent resistance and equivalent capacitance of the plasma in each channel are calculated in real time by using Fast Fourier Transform (FFT) and equivalent circuit fitting algorithm. This is used as an impedance fingerprint to characterize the discharge stability and arc column morphology.

[0021] Specifically, the control logic of the flow-electric field co-regulator is based on an impedance-flow-field coupling mapping model: This model establishes a quantitative relationship between impedance fingerprints of different discharge gaps, input gas flow velocity and discharge stability indicators (such as arc length fluctuation rate) through prior experiments or simulations. The controller compares the deviation between the monitored impedance fingerprint and the steady-state reference fingerprint in real time, calculates the required pulse phase correction and airflow speed adjustment by querying the coupling mapping model, and sends them to the corresponding actuators.

[0022] As an additional implementation, the plasma heater in this embodiment further includes: A closed-loop emission control system based on spectral diagnostics includes a fiber optic spectral probe facing the discharge region and a spectral analyzer. By analyzing the intensity of specific nitrogen oxide (NO, NO2) characteristic spectral lines in the plasma emission spectrum in real time, their generation rate can be inverted. When the generation rate exceeds the threshold, the flow field-electric field co-regulator executes the high-temperature arc column maintenance mode: while keeping the total power constant, it increases the discharge current to above the set value on the one hand, and adjusts the airflow composition (such as introducing a trace amount of oxygen-enriched air) and flow rate on the other hand, actively suppressing the generation of nitrogen oxides through the dual pathways of thermodynamics and chemical kinetics.

[0023] The plasma heater in this embodiment firstly achieves a high power output of up to 1800W and a plasma jet length of 220mm. Its eight-phase parallel power supply and optimized electrode structure fundamentally solve the problems of low single-phase discharge power and easy arc extinction, achieving unprecedented stable heating performance. Secondly, the innovative "copper high-voltage electrode-graphite common ground electrode" pairing scheme fully leverages the advantages of both materials, greatly enhancing the electrode assembly's resistance to electrolytic corrosion and its service life, thus solving the lifespan bottleneck of core consumable components. Thirdly, the ZVS resonant power supply technology, combined with an active heat dissipation and air intake system, enables an energy conversion efficiency exceeding 90% and effectively controls the thermal field distribution, thereby achieving extremely high thermal energy utilization efficiency. Finally, through precise electrical parameter control, the emission concentration of harmful NO2 gas is successfully and stably controlled at an extremely low level below 6.5ppm, far exceeding relevant national standards, truly achieving a perfect balance between high efficiency, long lifespan, and clean environmental protection.

[0024] Furthermore, the power supply system also includes a main power source and a boost module; The main power source is used to convert AC power at the power frequency into adjustable DC power; The resonant inverter circuit is connected to the main power source to convert DC power into high-frequency AC power, and its operating center frequency is about 40kHz. The boost module includes multiple parallel boost transformers, which are connected to the resonant inverter circuit to boost the high-frequency AC power to a high voltage with a pulse peak of over 20kV, so as to excite and maintain the arc discharge.

[0025] Furthermore, the resonant inverter circuit is an eight-phase parallel structure, comprising multiple independent resonant units; Each resonant unit drives a step-up transformer and supplies power to a corresponding high-voltage electrode.

[0026] Furthermore, the power supply system in this embodiment is responsible for converting mains power into high-voltage pulses suitable for generating and maintaining a stable plasma jet. Its core lies in employing a resonant inverter circuit based on zero-voltage switching. Specifically, the power supply system includes: Main power source: Converts industrial frequency AC power into adjustable DC power, with an output voltage range of 0-60V and an output current range of 0-84A, and integrates a complete protection circuit.

[0027] ZVS resonant inverter circuit: Connected to the main power source, it converts DC power into high-frequency AC power. Preferably, this circuit adopts an eight-phase parallel structure, consisting of eight independent ZVS units, with an operating center frequency of approximately 40kHz. Zero-voltage switching technology effectively reduces switching losses, enabling the system conversion efficiency to exceed 90%.

[0028] Boost module: Includes multiple parallel boost transformers, which are connected to the output terminals of each ZVS unit to boost the high-frequency AC power to a high voltage with a pulse peak value of up to 20kV or more, providing sufficient energy for discharge.

[0029] To further optimize the technical solution, the main power source of the power system in this embodiment adopts a programmable switching power supply module, which converts AC 220V / 50Hz mains power into adjustable DC power. This power supply module has comprehensive protection functions, including overvoltage protection, overcurrent protection, and overtemperature protection. It immediately cuts off the output when the output voltage exceeds 65V, responds immediately when the output current exceeds 90A, and automatically reduces power when the heatsink temperature exceeds 85℃.

[0030] The output is equipped with a large-capacity electrolytic capacitor filter array to ensure that the output ripple voltage is below 200mV. The feedback voltage can be adjusted via a multi-turn precision potentiometer on the panel, allowing for precise control of the output voltage within the 0-60V range, and the output current is adjustable within the 0-84A range. This power source employs soft-switching technology, achieving a power conversion efficiency exceeding 90%, providing a stable power input for plasma discharge.

[0031] The generating circuit is built based on the ZVS (Zero Voltage Switching) resonance principle. The circuit includes two N-channel MOSFETs (Q1, Q2), a resonant capacitor C1 (0.47μF capacitance, 400V withstand voltage), a resonant inductor L1 (using the primary coil of a transformer, with an inductance of approximately 100μH), and gate drive resistors (R1 and R2 are 470Ω, R3 and R4 are 10kΩ).

[0032] When the circuit is operating, the resonant effect of capacitor C1 and inductor L1 achieves zero voltage across the switching transistor when it is turned off and on, thus significantly reducing switching losses. This circuit converts direct current into high-frequency alternating current, with an operating center frequency of approximately 40kHz.

[0033] The boost circuit uses a high-voltage transformer as the step-up transformer, which boosts the high-frequency AC power to a high voltage of over 20kV pulse peak through the transformer turns ratio. This design effectively reduces energy loss, improves overall efficiency, and ensures that the plasma cooker minimizes heat loss during operation.

[0034] To overcome the shortcomings of low single-phase discharge power, short plasma jet, and easy arc extinction, this invention adopts an eight-phase parallel circuit structure, such as... Figure 1 As shown. The specific implementation method is as follows: Eight identical ZVS units were constructed and connected in parallel. Each unit includes a complete resonant circuit and a power switch. Each ZVS unit drives an independent high-voltage transformer, and the secondary outputs of the eight transformers are connected to eight high-voltage electrodes respectively. The circuits of each phase use the same component parameters and layout to ensure consistent operating characteristics.

[0035] The eight-phase parallel structure increases the total power to eight times that of a single-phase discharge, resulting in a more stable plasma jet with significantly increased jet length and area. Experiments show that, compared to single-phase discharge, eight-phase discharge improves plasma jet stability by over 70%, and the jet length increases from less than 50 mm in single-phase discharge to 220 mm.

[0036] It should be noted that the power supply system in this embodiment adopts a phase-shift series resonant topology: The eight resonant inverter units are not completely independent and connected in parallel, but are coupled in series and synchronized in phase through a master-slave digital phase-locked loop network; The network maintains a preset, dynamically adjustable small phase offset between the output high-voltage pulses of the eight units. This offset corresponds to the phase difference command output by the flow-electric field co-controller, and is used to actively decouple electromagnetic interference between adjacent discharge channels at the electrical level.

[0037] Specifically, the master-slave digital phase-locked loop network has fault-tolerant resynchronization capabilities: When a resonant inverter unit is detected to be outputting abnormally due to a fault, the network can quickly isolate the unit from the phase synchronization chain. The optimal phase relationship between the remaining seven units is recalculated, and the overall stability of the discharge array is maximized in derating mode by dynamically adjusting the phase offset.

[0038] To further optimize the technical solution, the power supply system in this embodiment can also be extended to a fault-tolerant multiphase resonant high-voltage source to generate multiple high-voltage pulses. Its topology allows for reconfiguration in the event of a single or multiple power unit failure, maintaining basic output in a degraded mode. The fault-tolerant multiphase resonant high-voltage source adopts a topology combining modular cascaded H-bridges and a shared resonant cavity: The outputs of multiple full-bridge power modules are connected in parallel and then connected to a reconfigurable LC resonant network. When a fault is detected in a full-bridge module, the control system adjusts the equivalent parameters of the reconfigurable LC resonant network and reallocates the pulse width modulation phase of the remaining healthy modules, so that the system can still maintain the output voltage waveform quality and effective excitation of the discharge load even when the total output power and capability decrease.

[0039] Furthermore, in the multiphase discharge device, multiple high-voltage electrodes are distributed in a ring array; The axis of each high-voltage electrode is tilted upward relative to the horizontal plane, so that the discharge tip is spatially opposite to the tip of the central common electrode, thereby shortening the discharge distance and improving stability.

[0040] Furthermore, in this embodiment, the axis of the high-voltage electrode is arranged at an angle relative to the axis of the central common electrode, so that the discharge tip of each high-voltage electrode points spatially to the corresponding discharge tip region of the central common electrode, thereby forming multiple shortened, spatially converging discharge gaps.

[0041] As an additional implementation, the multiphase discharge device of this embodiment includes: A central graphite common-ground electrode with multiple discharge tips on its serrated surface; Eight copper high-voltage electrodes are arranged in a ring, and the tip of each high-voltage electrode and the corresponding tip of the common ground electrode form a discharge gap. Each discharge gap is physically surrounded by an independent micro gas chamber. The air inlet of the micro gas chamber is connected to one of the multiple independent adjustable airflow valves, and the air outlet is aligned with the discharge gap to form a local directional airflow barrier.

[0042] Furthermore, the central common ground electrode has a wolf-tooth-shaped structure with multiple discharge tips on its surface; Multiple high-voltage electrodes are arranged in a ring at equal intervals with the axis of the central common ground electrode as the center, and the axis of each high-voltage electrode is tilted upward by 10-30 degrees.

[0043] The multiphase discharge device is also equipped with an isolation plate to reduce the phenomenon of shared discharge channels during the multiphase discharge process.

[0044] Furthermore, in this embodiment, radially distributed high-temperature resistant insulating plates are provided in the annular region between the central common ground electrode and the surrounding high-voltage electrode. The insulating plate divides the annular region into multiple independent fan-shaped discharge chambers, each containing the tip of a high-voltage electrode and a portion of the tip surface of a central common-ground electrode.

[0045] Furthermore, the tip angle of the high-voltage electrode is different from that of the center common electrode, and the minimum distance between the tip of the high-voltage electrode and the tip surface of the opposite center common electrode is optimized within a specific range to achieve the best balance between electric field concentration, discharge stability and electrode life.

[0046] As an additional implementation, the tip of the copper high-voltage electrode integrates a miniature thermocouple array for real-time measurement of the temperature gradient distribution along the axial direction at the electrode tip. The flow field-electric field co-regulator also dynamically adjusts the airflow temperature (achieved by mixing hot and cold airflows) or flow rate to the micro air chamber corresponding to the electrode based on temperature gradient distribution data, thereby achieving precise point-to-point air cooling of the electrode hot spot area, optimizing the electrode heat load distribution, and extending service life.

[0047] Furthermore, the multiphase discharge device in this embodiment is electrically connected to the power supply system for directly exciting and forming a stable plasma torch in atmospheric pressure air. Specifically, it includes: Electrode Materials and Pairing: The multiphase discharge device employs a needle-needle discharge structure, comprising a central common-ground electrode and multiple high-voltage electrodes arranged around it. The high-voltage electrodes are made of copper to utilize its excellent electrical and thermal conductivity; while the central common-ground electrode is made of graphite to utilize its extremely high melting point and resistance to electro-erosion, which decreases with increasing current. This copper-graphite combination fundamentally solves the problem of electrode ablation under high-temperature arcs, significantly extending its lifespan.

[0048] Electrode structure and layout: Multiple copper high-voltage electrodes are arranged in a ring array, with the axis of each electrode tilted upwards relative to the horizontal plane. This ensures that the discharge tip is precisely aligned with the tip of the graphite common-ground electrode in space, thereby shortening the effective discharge distance, enhancing the electric field concentration, and significantly improving discharge stability and jet quality. The graphite common-ground electrode is preferably a serrated rod-shaped structure with multiple discharge tips processed on its surface to promote the formation of uniform, multi-channel discharge.

[0049] Anti-interference structure: An isolation plate is installed inside the discharge device to physically separate each discharge channel, effectively reducing the "channel sharing" phenomenon in multiphase discharge and further improving stability.

[0050] To further optimize the technical solution, the high-voltage electrode involved in this embodiment is made of pure copper, with a diameter of 4mm and a 60° conical tip. The ground electrode is made of high-purity graphite, with a diameter of 15mm and a surface processed into a wolf-tooth-shaped structure, having multiple discharge tips. The eight copper high-voltage electrodes are arranged in a ring array, with a graphite ground electrode located at the center.

[0051] The electrode fixing device uses PTFE material to machine the electrode holder, ensuring precise positioning of each electrode. The copper-graphite electrode pairing fully utilizes the excellent electrical and thermal conductivity of copper and the high-temperature resistance of graphite. Copper, as the high-voltage electrode, can quickly dissipate heat, while graphite, as the common ground electrode, can withstand the high temperature of the plasma arc column, significantly extending the electrode's service life.

[0052] To further optimize the technical solution, this embodiment optimizes the design based on the basic discharge device to form an ideal generator model: Each high-voltage electrode axis is tilted upwards at a 20° angle relative to the horizontal plane, ensuring that its tip is precisely aligned with the tip of the common ground electrode in space, thus reducing the effective discharge distance to 8mm. An alumina ceramic insulating plate is installed in the discharge area, dividing it into eight independent zones to effectively prevent the sharing of discharge channels.

[0053] The power supply system and discharge device system are integrated into the same stove body. The firepower is controlled by adjusting the input voltage via a knob. An aluminum heat sink and a DC blower are installed below the common electrode to cool the electrode and provide uniform airflow to the discharge area, controlling the distribution of the high-temperature zone of the electric arc and the morphology of the entire synthesized electric arc jet.

[0054] Precise control of the plasma jet is achieved by adjusting the input DC voltage (15-30V) and current (20-60A). Experimental data shows that: Input power 300W (15V / 20A): jet length 30mm, temperature 1000-2000K; Input power 800W (20V / 40A): jet length 120mm, temperature 3000-4000K; Input power 1800W (30V / 60A): jet length 220mm, temperature 5000-6000K; The jet length is positively correlated with the input power; for every 300W increase in power, the jet length increases by approximately 50mm. By adjusting the input voltage with a knob, three power levels can be switched: "low (300W), medium (800W), and high (1800W)," to meet different cooking needs such as stewing, frying, and stir-frying.

[0055] The generation of harmful gases was suppressed by optimizing discharge parameters. Uneven local temperature distribution in the plasma leads to the reaction of N2 and O2 to generate NO2 under non-thermal equilibrium conditions. The control method involves increasing the discharge current to keep the lowest boundary temperature of the arc column above 2000K, thus suppressing the non-thermal equilibrium reaction. Experiments verified that when the current is ≥48mA, the NO2 concentration remains stable below 6.5ppm.

[0056] Using XLA-BX-NO x The portable gas detector, at its maximum power of 1800W, measured NO2 concentration at 6.50ppm, O3 concentration at 1.45ppm, and no CO was detected. These values ​​are far below the NO2 concentration specified in GB16410-2020 "Household Gas Stoves". x The standard is ≤60ppm for CO and ≤60ppm for CO.

[0057] This embodiment also employs multiple measures to improve system stability: The multiphase discharge circuit adopts a "star grounding" design, with each ZVS unit independently grounded to reduce ground loop interference. A ferrite magnetic ring is fitted over the high-voltage transformer to reduce high-frequency radiation. Experimental results show that under strong electromagnetic interference of 1V / m, the system performance decreases by only 12%, which is superior to traditional induction cookers (which decrease by 25%).

[0058] Through electrode spacing optimization experiments, the optimal electrode spacing was determined to be 8 mm. When the electrode spacing increased from 5 mm to 15 mm, the arc extinction rate increased from 5% to 40%; by reducing the spacing to 8 mm and combining it with eight-phase current superposition, the arc extinction rate decreased to below 3%.

[0059] To further optimize the technical solution, the multiphase discharge device in this embodiment can also be extended into a decoupled multichannel discharge reactor, connected to a fault-tolerant multiphase resonant high-voltage source, and includes multiple physically and electrically isolated micro-discharge channels. Meanwhile, the decoupled multi-channel discharge reactor is equipped with a multi-physics field coupling monitoring and calculation unit and a multi-objective collaborative controller; The multi-physics field coupling monitoring and calculation unit is used to monitor the plasma impedance, emission spectrum characteristics, local gas flow velocity and electrode micro-region temperature of each micro-discharge channel in real time and calculate the characteristic parameters characterizing the stability, chemical reaction process and thermal load state of each channel. The multi-objective coordinated controller has its input end connected to a multi-physics field coupling monitoring and calculation unit, and its output end is simultaneously connected to a fault-tolerant multiphase resonant high-voltage source and a multi-dimensional active flow field generation system. Among them, the multi-dimensional active flow field generation system provides each micro-discharge channel with independently controllable airflow, temperature and composition; The multi-objective coordinated controller is configured to: solve a multi-input multi-output control problem in real time based on characteristic parameters, with channel stability index, nitrogen oxide generation rate and electrode hot spot temperature as key controlled variables, and output joint control commands to dynamically adjust the high-voltage pulse parameters and gas inlet parameters of the corresponding channels, thereby achieving independent and precise closed-loop control of the plasma state of each micro-discharge channel.

[0060] Specifically, the decoupled multi-channel discharge reactor includes: A central common-ground electrode with multiple insulatingly separated discharge protrusions on its surface; Multiple high-voltage electrodes are distributed in a ring, and each high-voltage electrode is directly opposite a discharge protrusion of the central common ground electrode, forming a pair of discharge gaps; Between two adjacent pairs of discharge gaps, a solid insulating barrier extending into the discharge area is provided. The solid insulating barrier completely isolates each discharge channel mechanically and electrically, fundamentally eliminating plasma crosstalk and sharing phenomena between channels.

[0061] Specifically, the multiphysics coupling monitoring and solution unit includes: The impedance spectrum and arc acoustic emission joint analysis module injects multi-frequency detection signals into the discharge channel and collects voltage response and acoustic emission signals. It uses a joint blind source separation algorithm to distinguish the impedance change components caused by arc length fluctuations and electrode morphology changes, thereby more accurately inverting the real-time physical state of the arc. The coaxial diagnostic module for laser-induced fluorescence and emission spectroscopy adopts a common optical path design, simultaneously acquiring the spontaneous emission spectrum of plasma and the laser-induced fluorescence signal for specific molecules (such as NO), enabling in-situ, quantitative, and dynamic monitoring of the formation process of harmful products.

[0062] Specifically, the multidimensional active flow field generation system configures a micro gas path unit for each micro-discharge channel, and each micro gas path unit includes: Mass flow controller, used to precisely regulate intake airflow; Miniature Peltier thermostat for regulating intake air temperature; The miniature gas mixing chamber can selectively mix small amounts of reactive gases (such as oxygen) or inert gases (such as argon) to actively regulate the local chemical reaction environment of the discharge region.

[0063] Specifically, the multi-objective cooperative regulator adopts a model predictive control framework, which internally includes a multi-physics coupled reduced-order model: This reduced-order model is extracted from the high-fidelity computational fluid dynamics-plasma model using the intrinsic orthogonal decomposition method. It can quickly predict the changing trends of channel stability, NOx generation and electrode temperature under different pulse parameters and inlet parameters. In each sampling period, the controller performs rolling optimization for the next few steps based on this model to find the optimal joint control command sequence that makes multiple controlled variables closest to the desired trajectory.

[0064] Specifically, each discharge protrusion of the central common electrode is embedded with a fiber optic temperature sensor array. The multi-physics coupling monitoring and calculation unit obtains the three-dimensional temperature gradient field from the surface to the depth inside the discharge protrusion by demodulating the wavelength drift of the fiber grating, providing a precise assessment basis for the internal thermal stress of the electrode for the multi-target coordinated controller.

[0065] Furthermore, the plasma heater also includes: An integrated heat dissipation and air intake system is located below the central common ground electrode; The integrated heat dissipation and air intake system includes heat dissipation components and a blower to cool the electrodes and supply air to the discharge area in order to control the arc morphology and improve thermal efficiency.

[0066] Furthermore, the integrated heat dissipation and air intake system in this embodiment is an active heat dissipation and airflow management unit integrated at the bottom of the discharge device: the unit includes heat sinks attached to the electrode base and a blower fan located below. The airflow generated by the blower fan performs two functions simultaneously: forced air cooling of the central common electrode; and delivery of cooling air to each discharge gap to stabilize the arc morphology and participate in plasma chemical reactions.

[0067] Furthermore, the heater also includes an integrated heat dissipation and air intake system. This system, located below the common ground electrode, includes heat sinks and a blower fan. Its function is dual: firstly, it provides forced air cooling to the electrodes (especially the high-temperature common ground electrode); secondly, it draws in air from the bottom and delivers it to the discharge region, providing the necessary gas source for the arc, while simultaneously controlling the morphology and temperature field of the plasma arc column through airflow, thereby optimizing heating efficiency.

[0068] Furthermore, the power supply system also includes an electromagnetic interference suppression structure; The electromagnetic interference suppression structure includes a discharge unit and a magnetic ring fitted onto the high-voltage output end of the step-up transformer. The discharge unit is independently grounded using a star grounding method.

[0069] Furthermore, the power supply system of this embodiment has an anti-electromagnetic interference design, specifically including adopting a star grounding method to independently ground each ZVS discharge unit to reduce ground loop interference; and installing a ferrite magnetic ring on the high-voltage output terminal of the step-up transformer to suppress high-frequency electromagnetic radiation.

[0070] Furthermore, the power supply system continuously or in stages controls the power of the plasma jet by adjusting the input electrical parameters, achieving adjustment from a low power of 300W to a high power of 1800W.

[0071] Furthermore, this embodiment can achieve linear control of the total power of the plasma jet from low to high by continuously adjusting the input voltage and current of the power supply system, and simultaneously change the length and core temperature of the plasma jet.

[0072] Specifically, by adjusting the input voltage and current of the main power source, the length and power of the plasma jet can be continuously or in stages, achieving a wide range of linear power adjustment from 300W (low heat) to 1800W (high heat) to meet different cooking needs from stewing to stir-frying.

[0073] Furthermore, the high-voltage electrode is made of copper; The central common electrode is made of graphite.

[0074] Furthermore, this embodiment maintains the boundary temperature of the plasma arc column above 2000K by increasing and controlling the discharge current above 48mA, thereby suppressing the generation of nitrogen oxides and stabilizing the NO2 emission concentration below 6.5ppm.

[0075] Furthermore, the plasma heater in this embodiment also includes a health status assessment and remaining lifespan prediction module: This module continuously analyzes long-cycle data from the multiphysics coupling monitoring and calculation unit, combined with the on-resistance changes of power devices in the fault-tolerant multiphase resonant high-voltage source and the ablation rate of electrodes in the decoupled multichannel discharge reactor. By using survival analysis models, the failure time distribution of key components (such as MOSFETs and electrodes) can be predicted and early warnings can be provided to achieve predictive maintenance.

[0076] Furthermore, the heater startup process in this embodiment employs a stepped soft-excitation strategy: First, a reference plasma is formed by exciting a single discharge channel with low power and low gas flow. Then, based on the stable impedance spectrum of the reference channel, the remaining discharge channels are excited one phase at a time and according to a specific timing and parameter matching relationship through the flow field-electric field coordinated controller until all eight channels are working stably, avoiding strong electromagnetic interference and airflow turbulence caused by simultaneous excitation.

[0077] The heater in this embodiment includes a power supply system and a multiphase discharge device. The power supply system employs a resonant inverter circuit based on zero-voltage switching to convert mains power into controllable pulsed high-voltage direct current. This power is then used to drive multiple step-up transformers via an eight-phase parallel ZVS resonant unit. The plasma jet generated by the eight phases is more stable and has eight times the power of a single-phase jet, resulting in a larger plasma jet length and area. The multiphase discharge device uses a needle-needle structure, including a central common ground electrode made of graphite and multiple copper high-voltage electrodes arranged in a ring array and tilted upwards, facing the discharge tip of the common ground electrode, effectively shortening the discharge distance and improving stability. The common ground electrode has a serrated structure with multiple discharge tips on its surface, and an insulating plate reduces channel sharing. The device also integrates a heat dissipation and air intake system to air-cool the electrodes and supply air, optimizing thermal efficiency. By adjusting the input electrical parameters, continuous power control from 300W to 1800W can be achieved to meet various heating needs. In addition, by controlling the discharge current above 48mA, the plasma arc column boundary temperature is maintained above 2000K, effectively suppressing the generation of nitrogen oxides and reducing NO2 emission concentration to below 6.5ppm, thus exhibiting efficient, stable, and environmentally friendly heating performance.

[0078] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A plasma heater, characterized in that, include: A power supply system used to convert mains power into controllable high-voltage direct current; A multiphase discharge device, electrically connected to the power supply system, is used to generate a plasma jet; Active discharge stability enhancement system; Closed-loop emission control system based on spectral diagnostics; The power supply system includes a resonant inverter circuit based on zero-voltage switching; The multiphase discharge device includes a central common ground electrode and multiple high-voltage electrodes arranged around it, forming a needle-needle discharge structure. The active discharge stability enhancement system includes: The plasma impedance spectrum online monitoring unit is used to acquire the dynamic complex impedance spectrum of each discharge channel in real time. A flow-electric field coordinated controller is used to synchronously adjust two actuators based on a dynamic complex impedance spectrum. First, control the phase difference of the output pulses of the power supply system to each discharge channel; Secondly, the opening of the multi-channel independent adjustable airflow valve integrated at the bottom of the discharge device is controlled to deliver customized airflow to each discharge gap, thereby actively suppressing channel sharing and arc extinction through the synergistic effect of airflow mechanics and electrical parameters. The closed-loop emission control system based on spectral diagnostics includes a fiber optic spectral probe and a spectral analyzer oriented towards the discharge region.

2. The plasma heater according to claim 1, characterized in that, The power system also includes a main power source and a boost module; The main power source is used to convert industrial frequency AC power into adjustable DC power; The resonant inverter circuit is connected to the main power source and is used to convert the direct current into high-frequency alternating current. The boost module includes multiple boost transformers connected in parallel, used to boost the high-frequency AC power to a high voltage.

3. The plasma heater according to claim 1, characterized in that, The resonant inverter circuit is an eight-phase parallel structure, including multiple independent resonant units; Each resonant unit drives a step-up transformer and supplies power to a corresponding high-voltage electrode.

4. The plasma heater according to claim 1, characterized in that, In the multiphase discharge device, the multiple high-voltage electrodes are arranged in a ring array; The axis of each high-voltage electrode is inclined upward relative to the horizontal plane, so that the discharge tip is spatially opposite to the tip of the central common-ground electrode.

5. The plasma heater according to claim 1, characterized in that, The central common ground electrode has a wolf-tooth-shaped structure, and its surface is provided with multiple discharge tips; The multiphase discharge device is also equipped with an isolation plate to reduce the phenomenon of shared discharge channels.

6. The plasma heater according to claim 1, characterized in that, The plasma heater further includes: An integrated heat dissipation and air intake system is located below the central common ground electrode; The integrated heat dissipation and air intake system includes heat dissipation components and a blower, used to cool the electrodes and supply air to the discharge area.

7. The plasma heater according to claim 1, characterized in that, The power supply system also includes an electromagnetic interference suppression structure; The electromagnetic interference suppression structure includes a discharge unit and a magnetic ring fitted onto the high-voltage output end of the step-up transformer. The discharge unit is independently grounded using a star grounding method.

8. The plasma heater according to claim 1, characterized in that, The power system controls the power of the plasma jet continuously or in stages by adjusting the input electrical parameters, thereby achieving power adjustment from low to high.

9. The plasma heater according to claim 1, characterized in that, The high-voltage electrode is made of copper; The central common electrode is made of graphite.

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