Power output method, device and system based on filament current and magnetic field current

Abstract

The invention belongs to the technical field of microwave sources, and provides a filament current and magnetic field current-based power output method, device and system, the method comprises the execution of a plurality of cycles, and the nth cycle comprises the following steps: obtaining and executing a control strategy, then collecting the real-time power of a magnetron, if the deviation value between the real-time power of the magnetron and the target power is within the set range, all the n periods are completed, otherwise, the n + 1th period is entered, and n is larger than or equal to 1; and after all periods are completed, if the deviation value between the real-time power and the target power is greater than a set value and the duration time exceeds the set time, re-executing the power output method. According to the method, a filament current control strategy, a magnetic field current control strategy and a power control strategy are adopted, the three strategies are in a synergistic effect, and the multiple strategies are organically fused, so that the operation of the magnetron is more stable and adaptive.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microwave sources, and particularly relates to a power output method, device and system based on a filament current and a magnetic field current. BACKGROUND

[0002] In an industrial microwave application scenario, there are still many obvious defects in the power control of a magnetron by a microwave generator, mainly in the following aspects: First, the single problem of filament control. If the filament current is too low, the cathode temperature will be insufficient, resulting in attenuation of electron emission energy, causing instantaneous power drop. In serious cases, it may also cause sparking, frequency fluctuation and other phenomena, not only shortening the service life of the magnetron, but also possibly directly causing damage to the device. Conversely, if the filament current is too high, the cathode temperature will be too high, causing excessive electron emission, resulting in power attenuation in the long-term working state and shortening the service life by nearly half.

[0003] Second, the limitation caused by magnetic field solidification. Ordinary magnetrons use permanent magnets, and the magnetic field strength cannot be adjusted. Although industrial magnetrons use electromagnets, there is a lack of coordinated control strategy with the emission characteristics of the filament, which easily leads to instability of the electron cloud (such as spoke-like distribution of dispersion adjustment).

[0004] In addition, there is an inherent contradiction between life and power: filament overheating will accelerate cathode aging, and excessive magnetic field strength may cause electron back bombardment and cause extinguishing, which all restrict the stable operation of the magnetron. SUMMARY

[0005] In order to solve the problems in the background art, the application provides a power output method, device and system based on a filament current and a magnetic field current.

[0006] In order to achieve the above-mentioned purpose, the application adopts the following technical solutions: The power output method based on the filament current and the magnetic field current is executed for a plurality of periods, and the nth period comprises the following steps: A control strategy is acquired and executed, the control strategy comprising a filament current control strategy, a magnetic field current control strategy and a power control strategy; After the control strategy is executed, the real-time power of the magnetron is collected, and if the deviation value of the real-time power of the magnetron and the target power is within a set range, all n periods are completed, otherwise the (n+1)th period is entered, n≥1; After all the periods are completed, if the deviation value of the real-time power and the target power is greater than a set value and the duration exceeds a set time, the power output method is re-executed.

[0007] Further, before the control strategy is acquired and executed, a preparation step within or outside the period is further included, and the preparation step comprises: acquire a target power of the magnetron; determine a power interval of the magnetron based on the target power, and determine a corresponding control strategy according to the power interval.

[0008] Further, the determination of the power interval of the magnetron based on the target power comprises the following steps: comparing the target power with a rated power of the magnetron to determine the power interval of the magnetron.

[0009] Further, the power interval comprises a low power segment and a high power segment, and the corresponding filament current control strategy is executed based on the power interval, which comprises executing a control parameter calling instruction according to the power interval to generate the control strategy corresponding to each power interval. The control parameter comprises a correction factor constant K 3, a filament current index a , a magnetic field strength index b , a magnetron parameter K , an initial magnetic field current reference value, an initial filament current reference value, a PID parameter and a decoupling compensation coefficient.

[0010] Further, the power interval comprises a low power segment, a medium power segment and a high power segment. The control strategy corresponding to the low power segment comprises: setting the magnetic field current to 37%~42% of the rated magnetic field current; executing the corresponding filament current control strategy and power control strategy; and / or, the control strategy corresponding to the medium power segment comprises: executing the corresponding filament current control strategy, magnetic field current control strategy and power control strategy; and / or, the control strategy corresponding to the high power segment comprises: setting the value of the filament current to be less than 20% of the rated filament current; executing the corresponding magnetic field current control strategy and power control strategy.

[0011] Further, the execution of the filament current control strategy comprises the following steps: generating a reference value of the filament current; acquiring a real-time filament current of the magnetron and comparing it with the reference value of the filament current; outputting a first control instruction based on the comparison result to adjust the filament current of the magnetron, forming a closed-loop control of the filament current.

[0012] Further, the reference value of the filament current satisfies: ; In the formula, represents the reference value of the filament current; represents the reference value of the magnetic field current of the last period; is the target power K 3 is a correction factor constant; a is a filament current index;b is a magnetic field strength index; K is a magnetron parameter, and is a constant.

[0013] Further, the magnetic field current control strategy is executed, including the following steps: generating a reference value of the magnetic field current; collecting a real-time magnetic field current of the magnetron, and comparing the real-time magnetic field current with the reference value of the magnetic field current; outputting a second control instruction to adjust the magnetic field current of the magnetron based on the comparison result, to form a closed-loop control of the magnetic field current.

[0014] Further, the reference value of the magnetic field current satisfies: ; In the formula, represents the reference value of the magnetic field current; represents a reference value of a filament current in a previous period; is a target power; K 3 is a correction factor constant; a is a filament current index; b is a magnetic field strength index; K is a magnetron parameter, and is a constant.

[0015] Further, the power control strategy is executed, including the following steps: after the filament current control strategy and / or the magnetic field current control strategy are executed, collecting a real-time power of the magnetron, and comparing the real-time power with the target power; outputting a correction amount of the filament current and the magnetic field current based on the comparison result; inputting the real-time power of the magnetron, the correction amount of the filament current, and the correction amount of the magnetic field current into a next period.

[0016] Further, when the target power is greater than 0 and less than or equal to 30% of a rated power, the magnetron is in a low power section; when the target power is greater than 30% and less than or equal to 70% of the rated power, the magnetron is in a medium power section; and when the target power is greater than 70% and less than or equal to 100% of the rated power, the magnetron is in a high power section.

[0017] The application provides a power output device based on a filament current and a magnetic field current, which comprises a magnetron and a microwave power supply for supplying power to the magnetron, and further comprises a processor for executing the above method.

[0018] The application further provides a power output system based on a filament current and a magnetic field current, which comprises: a first processing unit, configured to obtain a target power of the magnetron; and to determine a power range of the magnetron based on the target power or the real-time power; and, if the real-time power of the magnetron is within a set range, to determine that all n cycles have been completed; otherwise, the first processing unit executes a next cycle; A control unit, configured to execute a corresponding control strategy based on the power interval, the control strategy including a filament current control strategy, a magnetic field current control strategy, and a power control strategy; Power sensor, used to collect the real-time power of the magnetron after executing the control strategy; The starting unit is used to restart the first processing unit, the control unit and the power sensor to execute the corresponding strategy after all cycles are completed if the deviation between the real-time power and the target power is greater than the set value and the duration exceeds the set time.

[0019] Furthermore, the control unit includes: A filament current controller, configured to generate a reference value of the filament current; and to collect the real-time filament current of the magnetron; a filament loop PID regulator, configured to compare the real-time filament current of the magnetron with a reference value of the filament current, and output a first control instruction based on the comparison result to adjust the filament current of the magnetron, thereby forming a closed-loop control of the filament current; A magnetic field current controller, configured to generate a reference value of the magnetic field current; and to acquire the real-time magnetic field current of the magnetron; A magnetic field loop PID regulator is used to compare the real-time magnetic field current of the magnetron with a reference value of the magnetic field current, and output a second control instruction based on the comparison result to adjust the magnetic field current of the magnetron, thereby forming a closed-loop control of the magnetic field current; And, a power PID regulator is used to compare the real-time power of the magnetron with the target power after the filament current control strategy and / or the magnetic field current control strategy are executed, and output the correction amount of the filament current and the magnetic field current based on the comparison result, and input the real-time power of the magnetron, the correction amount of the filament current and the correction amount of the magnetic field current into the next cycle.

[0020] Beneficial effects of the present invention: The method of the present application adopts a filament current control strategy, a magnetic field current control strategy and a power control strategy, which work together, on the one hand, by accurately grasping the dynamic correlation between the filament current and the electron emission density, the limitation of traditional filament control is broken, and the electron emission state can be flexibly adjusted according to the actual demand; on the other hand, by means of the corresponding relationship between the magnetic field strength and the magnetic field current, the dynamic regulation of the magnetic field is realized, which not only solves the problem of permanent magnet magnetron magnetic field solidification that cannot be adjusted, but also makes up for the defect that the magnetic field and the filament emission characteristics in the industrial magnetron lack cooperation; the power control strategy can feedback the results of the filament current control strategy and the magnetic field current control strategy, and can calculate the correction amount of the next period. The organic integration of such multi-strategies makes the operation of the magnetron more stable and adaptable.

[0021] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and attained by the structure particularly pointed out in the description and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0023] Figure 1 The first embodiment of the power output method based on filament current and magnetic field current of the present application is shown; Figure 2 The second embodiment of the power output method based on filament current and magnetic field current of the present application is shown; Figure 3 The structure block diagram of the power output system based on filament current and magnetic field current of the present application is shown. DETAILED DESCRIPTION

[0024] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0025] The power output method based on filament current and magnetic field current of the present application is executed for several periods, the nth period includes the following steps: Acquiring and executing a control strategy, wherein the control strategy includes a filament current control strategy, a magnetic field current control strategy, and a power control strategy; After executing the control strategy, the real-time power of the magnetron is collected. If the deviation between the real-time power of the magnetron and the target power is within the set range, then all n cycles are completed. Otherwise, the n+1th cycle is entered, where n≥1. After all cycles are completed, if the deviation between the real-time power and the target power is greater than the set value and the duration exceeds the set time, the power output method is re-executed.

[0026] Before executing several cycles or in each cycle, a preparation step may be included. The preparation step includes: Obtaining a target power of the magnetron; determining a power range of the magnetron based on the target power, and determining a corresponding control strategy according to the power range.

[0027] For example, after obtaining the target power of the magnetron, the target power can be compared with the rated power of the magnetron to determine the power range that the magnetron is in. Then, a control parameter call instruction is executed according to the power range to generate a control strategy corresponding to each power range.

[0028] Specifically, there are at least two power intervals in the embodiment of the present application. The control parameters include the correction factor constant K 3. Filament current index a , magnetic field intensity index b , magnetron parameters K , initial magnetic field current reference value, initial filament current reference value, PID parameters and decoupling compensation coefficient. It can be understood that different power ranges can have different control parameters.

[0029] It is understood that a power range is a power segment designed for the adjustable range of rated power. At different output powers, the operating state of the magnetron varies. This application optimizes magnetron control by dividing the power range into different power ranges (hereinafter referred to as power ranges) and using corresponding control strategies for each power range. For example, three power ranges can be set: a low power range, a medium power range, and a high power range. It is understood that different numbers of power ranges can also be designed for different magnetrons. The number of power ranges can also be two (for example, divided only into a high power range and a low power range), or the number of power ranges can be more than three (for example, in addition to the high power range and the low power range, at least two medium power ranges are set).

[0030] Each power interval / power segment corresponds to a different control strategy. In the present application, the control strategy for each power interval specifically includes: at least one of a filament current control strategy and a magnetic field current control strategy; and a power control strategy.

[0031] In the examples of this application: The control strategy corresponding to the low power segment may be: setting the magnetic field current to a fixed value, for example, 37% to 42% of the rated magnetic field current; and executing the corresponding filament current control strategy and power control strategy.

[0032] The control strategy corresponding to the low power section may also be: executing the corresponding filament current control strategy, magnetic field current control strategy and power control strategy.

[0033] The control strategy corresponding to the medium power segment may be: executing the corresponding filament current control strategy, magnetic field current control strategy and power control strategy.

[0034] The control strategy corresponding to the high power segment may be: setting the filament current to a fixed value, for example, to less than 20% of the rated filament current, and executing the corresponding magnetic field current control strategy and power control strategy.

[0035] The control strategy corresponding to the high power segment may also be: executing the corresponding filament current control strategy, magnetic field current control strategy and power control strategy.

[0036] The power output method of the present application will be described in detail below with reference to the specific embodiments shown in the accompanying drawings.

[0037] like Figure 1 As shown, a power output method based on filament current and magnetic field current is performed for several cycles, and the nth cycle includes the following steps: S1: Get the target power of the magnetron.

[0038] S2: Determine the power range of the magnetron based on the target power.

[0039] S3: Execute corresponding control strategies based on the power range, including filament current control strategy, magnetic field current control strategy and power control strategy.

[0040] S4: After executing the control strategy, the real-time power of the magnetron is collected. If it is within the set range, n cycles (this cycle) are all completed. Otherwise, it enters the next cycle, where n is greater than or equal to 1.

[0041] S5: After all cycles are completed, if the deviation between the real-time power and the target power is greater than the set value and the duration exceeds the set time, the power output method is re-executed.

[0042] It should be noted that a magnetron is a device that generates electrons. The filament is part of the magnetron, and the magnetic field current is directed to the electromagnet. The electromagnet is a device used to generate a magnetic field and is typically mounted outside the magnetron body. Electron emission from the magnetron is controlled by controlling the filament current input to the magnetron and the magnetic field current input to the electromagnet. In this embodiment, the magnetron is understood to be the entire unit including the magnetron body and electromagnet, and the target power is understood to be the target value of the magnetron's output power.

[0043] To help understand the relationship between the various parameters of the magnetron, in S1-S4, the filament current ( I f ) is the electron emission density control variable, and the magnetic field current ( I m ) is the electron cyclotron motion control variable. By establishing a nonlinear mapping relationship between the two and the output power, precise control of power output is achieved. Therefore, when executing S1-S4, it is necessary to understand the nonlinear mapping relationship between filament current and electron emission density, the functional relationship between magnetic field strength and magnetic field current, and the relationship between the magnetron's output power, electron emission density, and magnetic field current.

[0044] 1) Mapping relationship between electron emission density and filament current Filament temperature T The current satisfies Joule's law: ; (1) Where, K 1 is the heat-to-work conversion coefficient (take 0.85~0.92), R f is the filament resistance (0.023~0.15Ω at 25℃), t is the filament power-on time (s), K 2 is the heat dissipation coefficient (take 0.02~0.05), T 0 is the ambient temperature (℃); I f Indicates the filament current (A).

[0045] Electron emission density J Following the Richardson-Deschmann equation: ; (2) Where, A is the Richardson constant (take 32A / (cm 2. K 2 ), φ is the work function (tungsten filament takes 4.5eV), K b is the Boltzmann constant (1.380649×10 -23 J / K); T 阴极Absolute temperature of the filament (cathode), T Lamp filament temperature (℃).

[0046] 2) Magnetic field strength and magnetic field current relationship ; (3) In the formula, K 3 is a correction factor constant, μ0 is the vacuum permeability (4π×10 -7 H / m), N N is the total number of turns of the coil, I m I is the magnetic field current, unit A; L L is the length of the coil, unit meter.

[0047] 3) Filament current, magnetic field current cooperative power output relationship, that is, the relationship between the output power of the magnetron and the electron emission density and the magnetic field current ; (4) In the formula, K 4 is a correction factor constant (0.002-0.01), J J is the electron emission density of the magnetron, unit A / m 2 ; B H is the magnetic field strength, unit A / m; V a V is the anode voltage, unit v; η is the conversion efficiency (usually the conversion efficiency of the magnetron is 0.6-0.9); P P is the output power of the magnetron, unit W, and the calculated result under ideal conditions can be equal to the target power.

[0048] For S1, in combination with the content of Figure 1 , the power output method based on the filament current and the magnetic field current usually contains n periods, and the S1 of the first period is different from the S1 of the subsequent periods. Specifically, the first period needs to set a target power according to the demand, and the target power can be calculated by formula (4). Exemplarily, after a period ends, it is needed to judge whether the deviation of the real-time power and the target power is within the predetermined range (exemplarily, the predetermined range can be set to 3% Pn , Pn of the rated power), if this condition is met, the whole process is completed.

[0049] In S2, the power interval of the magnetron is determined based on the target power, including the following steps: S201: The target power is compared with the rated power of the magnetron to determine the power interval of the magnetron.

[0050] S202: When the target power is greater than 0 and less than or equal to 30% of the rated power, the magnetron is in a low power section; when the target power is greater than 30% and less than or equal to 70% of the rated power, the magnetron is in a medium power section; when the target power is greater than 70% and less than or equal to 100% of the rated power, the magnetron is in a high power section.

[0051] It should be further pointed out that the adjustment mode of the filament current and the magnetic field current corresponding to each power section in S2 is different, which is not specifically limited in the embodiment, and exemplarily: When in the low power section: the fixed magnetic field current is 37%-42% of the rated value, the corresponding filament current control strategy and power control strategy are executed, including adjusting the filament current to dominate the power output, wherein the coefficients a=2.3, b=0.6 (a is the filament current index, and b is the magnetic field intensity index); When in the medium power section: the corresponding filament current control strategy, magnetic field current control strategy and power control strategy are executed, including the coordinated adjustment of the filament current and the magnetic field current, wherein the coefficients a=2.0, b=0.9; When in the high power section: the fixed filament current is 0-20% of the rated value, the corresponding magnetic field current control strategy and power control strategy are executed, including adjusting the magnetic field current to dominate the power output, wherein a=1.8, b=1.2.

[0052] In S3, the corresponding filament current control strategy is executed based on the power interval, including executing the control parameter calling instruction according to the power interval to generate the control strategy corresponding to each power interval. The control parameters include correction factor constants K 3, filament current index a , magnetic field intensity index b , magnetron parameters K , initial magnetic field current reference value, initial filament current reference value, PID parameters and decoupling compensation coefficients Exemplarily, when in the medium power section, the filament current control strategy and the magnetic field current control strategy can be synchronized, wherein the execution of the filament current control strategy includes the following steps: S301a: generating a reference value of the filament current.

[0053] S302a: collecting the real-time filament current of the magnetron and comparing it with the reference value of the filament current.

[0054] S303a: outputting a first control instruction to adjust the filament current of the magnetron based on the comparison result to form a closed-loop control of the filament current.

[0055] It needs to be further explained that the implementation of the filament current control strategy requires a filament current controller, which is used to collect the filament current and control the electron emission density. Through filament current control, the temperature control of the magnetron cathode can be realized, and the influence of temperature on the anode current and output power can be reduced.

[0056] Specifically, in step S301a, the reference value of the filament current satisfies: ; (5) In the formula, represents the reference value of the filament current; represents the reference value of the magnetic field current of the previous period; is the target power K 3 is a correction factor constant; a is the filament current index; b is the magnetic field strength index; K is a magnetron parameter, which is a constant.

[0057] In S3, the implementation of the magnetic field current control strategy includes the following steps: S301b: generating a reference value of the magnetic field current.

[0058] S302b: collecting the real-time magnetic field current of the magnetron and comparing it with the reference value of the magnetic field current.

[0059] S303b: outputting a second control instruction to adjust the magnetic field current of the magnetron based on the comparison result, forming a closed-loop control of the magnetic field current.

[0060] It needs to be noted that the implementation of the magnetic field current control strategy requires the use of a magnetic field current controller, which can collect the magnetic field current and ensure that the electrons can stably maintain the cycloidal motion state and keep synchronization with the microwave field through precise regulation of the electron motion trajectory. This control mechanism can effectively reduce the influence of two undesirable situations: one is that when the magnetic field is too weak, the electrons will directly reach the anode and cannot form oscillation; the other is that when the magnetic field is too strong, the electrons will return to the cathode, causing the system to extinguish.

[0061] Specifically, in step S301b, the reference value of the magnetic field current satisfies: ; (6) In the formula, represents the reference value of the magnetic field current; represents the reference value of the filament current of the previous period; is the target power; K 3 is a correction factor constant; a is the filament current index; b is the magnetic field strength index; K is a magnetron parameter, which is a constant.

[0062] In one embodiment of the application, for the filament current index in formula (5) and formula (6) a and the magnetic field intensity index b can be obtained by fitting a plurality of experimental data, and the experimental steps are as follows: by adjusting different target powers, a plurality of power output adjustment experiments are carried out, and the measured values of the a and b parameters after the system is stable are recorded. The least square method is used for fitting calculation. See Table 1 for details.

[0063] Table 1

[0064] Through Table 1, the least square method is used for fitting: a = 2.31-0.0052xP(±0.03), b = 0.61+0.0058x (±0.03).

[0065] In addition, from Table 1, the error between the calculated values of the fitting formula and the measured values is ≤±0.03, which meets the fitting accuracy requirement in the document. The a value is higher (2.29~2.30) in the low power segment, indicating that the filament current has a more significant impact on the power. Therefore, in one embodiment of the application, the control strategy adopted in the low power segment is to set the magnetic field current to a fixed value, while executing the corresponding filament current control strategy and power control strategy. In the high power segment, the a value decreases and the b value increases, which reflects the characteristics of the magnetic field current dominating the power adjustment. Therefore, in one embodiment of the application, the control strategy adopted in the high power segment is to set the filament current to a fixed value, while executing the corresponding magnetic field current control strategy and power control strategy.

[0066] In the application, the values of the filament current index a and the magnetic field intensity index b corresponding to various power segments are pre-stored in the system through a plurality of previous tests, so as to be retrieved by program instructions subsequently.

[0067] In S3, after the filament current control strategy and / or the magnetic field current control strategy are completed, the power control strategy can be executed, including the following steps: S304: Collecting the real-time power of the magnetron and comparing it with the target power; S305: Outputting the correction amount of the filament current and the magnetic field current based on the comparison result; S306: Inputting the real-time power of the magnetron, the correction amount of the filament current and the correction amount of the magnetic field current into the next cycle.

[0068] It should be noted that in S306, since there may be a certain deviation between the real-time power and the target power in this cycle, the deviation can correspond to the correction amount of the filament current and the magnetic field current, which is used in the control and adjustment of the filament current and the magnetic field current in the next cycle. In S4, the real-time power of the magnetron needs to be compared with the target power. If the deviation value of the real-time power and the target power is within the set range, the process ends and does not enter the next cycle. The embodiment does not specifically limit the set range. Exemplarily, the deviation value of the real-time power and the target power is ≤3% Pn ( Pn The rated power can also be selected as 2% Pn , 1% Pn or 0.5% Pn , that is, n cycles are considered to be all completed.

[0069] In general, the power output method based on the filament current and the magnetic field current collects and monitors the filament current, the magnetic field current and the output power according to the characteristics of the magnetron, and simultaneously performs PID adjustment on the filament current and the magnetic field circuit, so that the final real-time (output) power meets the pre-set target power.

[0070] Taking the first cycle of an experiment as an example, the process is as follows: Setting the target power: the user inputs the target power (such as 1.8kW), and the system obtains the target power.

[0071] Interval judgment: =30% Pn ( Pn The rated power is assumed to be 6kW, and it is judged that the power interval is in the low power section, and the control strategy is determined to be the control strategy corresponding to the low power section. Pn

[0072] Initialization: loading the magnetron parameters K =0.476, a=2.3, b=0.6), setting the initial filament current I f0 =32A, the initial magnetic field current I m0 =0.74A.

[0073] Solving the output: fixing the magnetic field current at 37% of the rated value (exemplarily, the rated magnetic field current is 2A), adjusting the filament current to dominate the power output; calculating the reference value of the magnetic field current ≈0.8A, and the reference value of the filament current ≈9.9A.

[0074] Closed-loop adjustment: Filament current control strategy: comparing the filament current of the current cycle with the reference value of the filament current + ΔI f1 ​) and then outputs the PWM duty cycle through the filament loop PID regulator.

[0075] Field current control strategy: Compare the deviation between the field current of this cycle and the field current reference value, and then output the PWM duty cycle through the field loop PID regulator.

[0076] Power control strategy: Calculate the deviation between the real-time (output) power and the target power in this cycle, and output the filament current based on the deviation I f Correction amount I f1 ; Output magnetic field current according to deviation I m Correction amount I m1 .

[0077] In S5, when all cycles are completed, the control and adjustment process ends. It can be understood that at this time, the magnetron has entered a normal working state and outputs at the target power.

[0078] When it is detected that the deviation between the real-time power of the magnetron and the target power is greater than 5% of the rated power and lasts for more than 200ms, it is necessary to re-run S1-S5.

[0079] like Figure 2 As shown, another optional implementation of the power output method based on the filament current and the magnetic field current is provided, wherein steps A1 and A2 do not participate in the cycle, specifically as follows: A1: Get the target power of the magnetron.

[0080] A2: Determine the power range of the magnetron based on the target power.

[0081] A3: Execute several cycles. The nth cycle includes the following steps: A301: Executes corresponding control strategies based on the power range, including filament current control strategy, magnetic field current control strategy, and power control strategy.

[0082] A302: After executing the control strategy, the real-time power of the magnetron is collected. If it is within the set range, all n cycles are completed. Otherwise, it enters the n+1th cycle, where n is greater than or equal to 1.

[0083] A4: After all cycles are completed, the adjustment control process stops and the magnetron outputs according to the target power. If the deviation between the real-time power and the target power is greater than the set value and lasts for more than the set time, the adjustment control process is restarted and the power output method is executed.

[0084] It should be noted that Figure 2 Methods andFigure 1 The difference lies in the different starting points of the cycles, where Figure 1 The steps S1 and S2 are involved in the cycle, Figure 2 Steps A1 and A2 are outside the cycle, for Figure 2 As for the method, it can be used in application scenarios where the target power is determined to be constant. Whether steps A1 and A2 participate in the loop will not affect the final output result. The running results are the same as Figure 1 The device and system can automatically modify the cycle-related settings of the two methods according to actual needs.

[0085] In some cases, when adjusting the output power of the magnetron based on the filament current and the magnetic field current, the target power may change. For example, the user changes the target power value. In this case, you can choose to perform the following operations: Figure 1 The method steps shown, that is, in each cycle, the preparation steps (S1, S2) are performed once to avoid the inability to respond to the change in time after the target power changes.

[0086] In other cases, the target power is fixed once it is entered. For example, after the target power is entered, the target power value is locked until the cycle is completed. In this case, you can choose Figure 2 The method steps shown are to perform a preparation step before the start of the cycle, determine the power range in which the target power is located, and then directly start to execute the corresponding control strategy until the power output meets the target power requirement. In this case, the process steps within the cycle are simplified and the efficiency is higher.

[0087] In particular, when the target power value is just near the dividing point of the two power intervals, it may be possible to actually achieve the output regulation of the target power by adopting the control strategies corresponding to the two adjacent power intervals. Pn ), if after a predetermined time (for example, 200ms), the control strategy corresponding to the power interval in which the target power is located cannot achieve the output adjustment of the target power, then the control strategy corresponding to the adjacent power interval is switched to perform power output adjustment until the adjustment is completed.

[0088] The second aspect of the present application also proposes a power output device based on filament current and magnetic field current, which comprises a magnetron and a microwave power supply for powering the magnetron, and a processor, which can execute the aforementioned power output method based on filament current and magnetic field current. Specifically, the device can be a microwave generator. As a device for generating microwaves, the microwave generator can be applied in a microwave plasma device, which uses plasma to process the surface of materials, remove dirt, and activate activity, and is suitable for semiconductor microelectronics, medical, optical, automotive, and other fields, with advantages of high efficiency, environmental protection, and selectivity. It can also be applied in the field of environmental protection, such as a microwave plasma torch, which can be used to process various solid waste (urban household garbage, industrial and hazardous solid waste, medical and electronic hazardous waste, sewage sludge, and smelting slag and mining tailings, etc.). A high-power industrial microwave generator device can also be applied in an MPCVD device for preparing synthetic diamond and carbon nanotube materials.

[0089] As shown in Figure 3 , a power output system based on filament current and magnetic field current is used in the power output method based on filament current and magnetic field current in the present application, which comprises: A first processing unit is used to obtain the target power of the magnetron, and to determine the power interval in which the magnetron is located based on the target power or real-time power. When the real-time power of the magnetron is within the set range, it is determined that all n cycles are completed, otherwise the first processing unit executes the next cycle.

[0090] A control unit is used to execute the corresponding control strategy based on the power interval, and the control strategy comprises a filament current control strategy, a magnetic field current control strategy, and a power control strategy. Specifically, the control unit generates reference signals for the filament current and the magnetic field current in combination with the output of the power PID regulator (power loop feedback). The filament current reference signal is input into the filament loop PID regulator, compared with the feedback value collected by the filament current, and outputs a control signal to the filament current controller to adjust the filament current, forming a filament current closed loop. The magnetic field current reference signal is input into the magnetic field loop PID regulator and the magnetic field current controller in the same way, forming a magnetic field current closed loop.

[0091] A power sensor is used to collect the real-time power of the magnetron after executing the control strategy. Specifically, the output power of the magnetron is continuously collected and fed back to the power PID regulator to correct the reference signal of the power loop. The closed-loop adaptive control module adaptively adjusts the PID parameters or control algorithm (such as switching from fuzzy PID to sliding mode control) according to real-time data such as power deviation and current fluctuation.

[0092] The starting unit is configured to restart the first processing unit, the control unit and the power sensor to execute corresponding strategies if the deviation between the real-time power and the target power is greater than a set value and the duration exceeds a set time after all cycles are completed.

[0093] Further, the control unit comprises: a filament current controller configured to generate a reference value of the filament current; and a real-time filament current of the magnetron is collected; a filament loop PID regulator configured to compare the real-time filament current of the magnetron with the reference value of the filament current, output a first control instruction to adjust the filament current of the magnetron, and form a closed-loop control of the filament current.

[0094] Further, the control unit comprises: a magnetic field current controller configured to generate a reference value of the magnetic field current; and a real-time magnetic field current of the magnetron is collected; a magnetic field loop PID regulator configured to compare the real-time magnetic field current of the magnetron with the reference value of the magnetic field current, output a second control instruction to adjust the magnetic field current of the magnetron based on the comparison result, and form a closed-loop control of the magnetic field current.

[0095] Further, the control unit comprises: A power PID regulator configured to compare the real-time power of the magnetron with the target power after the filament current control strategy and / or the magnetic field current control strategy is completed, output a correction amount of the filament current and the magnetic field current based on the comparison result, and input the real-time power of the magnetron, the correction amount of the filament current and the correction amount of the magnetic field current to the next cycle.

[0096] For the system embodiment, the hardware used in the system is not specifically limited, and examples are as follows: 1) The function of the first processing unit can be realized based on an STM32F103 microprocessor (MCU for short). The filament current controller and the magnetic field current controller are communicated through a universal synchronous / asynchronous receiver / transmitter (USART) to realize the output of control signals. At the same time, the sensor group signals are collected through a 12-bit ADC interface, and the sampling frequency is set to 10 kHz to ensure real-time data. Except for the power sensor, all the control and collection in the system block diagram are completed by the MCU.

[0097] The system MCU receives the set target power and reads the feedback value of the power sensor (or the output power set value of the microwave power supply) to determine the real-time power. Based on the target power, the power interval is judged by comparing with the 30%Pn and 70%Pn threshold values to determine the current interval (low power segment, medium power segment, high power segment), and the corresponding power algorithm module is selected. The low, medium and high power algorithm modules retrieve relevant control parameters (such as PID parameter adjustment instructions, decoupling compensation coefficients, etc.) according to the interval characteristics, and generate control strategies of the closed-loop adaptive control module for each interval.

[0098] 2) Filament current controller: full-bridge phase-shift PWM topology is adopted, the PWM control signal (frequency 20 kHz) output by MCU is input to the drive chip after isolation by optocoupler (model TLP250), the MOSFET full-bridge circuit is driven to realize 0~10V output voltage regulation. 3) The filament current signal collected is converted into voltage signal by Hall current sensor and fed back to MCU to obtain real-time filament current.

[0099] 4) Linear amplification circuit is adopted, MCU outputs 0~3.3V control signal through DAC (digital-to-analog converter), the signal is amplified to drive the electromagnetic coil, 0~2A magnetic field current regulation is realized; the magnetic field voltage signal collected by sampling resistor is filtered and fed back to MCU to obtain real-time magnetic field current.

[0100] 5) Real-time output power is collected by power sensor and fed back to MCU to realize 0~10kW power measurement.

[0101] Although the present application is described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A power output method based on filament current and magnetic field current, characterized in that: Execute a number of cycles, where the nth cycle includes the following steps: Acquiring and executing a control strategy, wherein the control strategy includes a filament current control strategy, a magnetic field current control strategy, and a power control strategy; After executing the control strategy, the real-time power of the magnetron is collected. If the deviation between the real-time power of the magnetron and the target power is within the set range, then all n cycles are completed. Otherwise, the n+1th cycle is entered, where n≥1. After all cycles are completed, if the deviation between the real-time power and the target power is greater than the set value and the duration exceeds the set time, the power output method is re-executed.

2. The power output method based on filament current and magnetic field current according to claim 1, characterized in that: Before obtaining and executing the control strategy, a preparation step within or outside the cycle is also included, and the preparation step includes: Obtain target power of magnetron; The power range of the magnetron is determined based on the target power, and the corresponding control strategy is determined according to the power range.

3. The power output method based on filament current and magnetic field current according to claim 2, characterized in that: The method of determining the power range of the magnetron based on the target power includes the following steps: Compare the target power to the rated power of the magnetron to determine the power range in which the magnetron is located.

4. The power output method based on filament current and magnetic field current according to claim 3, characterized in that: The power interval includes a low power segment and a high power segment, and the executing the corresponding filament current control strategy based on the power interval includes executing a control parameter calling instruction according to the power interval to generate a control strategy corresponding to each of the power intervals; The control parameters include a correction factor constant K 3. Filament current index a , magnetic field intensity index b , magnetron parameters K , initial magnetic field current reference value, initial filament current reference value, PID parameters and decoupling compensation coefficient.

5. The power output method based on filament current and magnetic field current according to claim 4, characterized in that: The power range includes a low power range, a medium power range and a high power range; The control strategy corresponding to the low-power segment includes: setting the magnetic field current to 37%~42% of the rated magnetic field current, and executing the corresponding filament current control strategy and power control strategy; and / or, the control strategy corresponding to the medium-power segment includes: executing the corresponding filament current control strategy, magnetic field current control strategy and power control strategy; and / or, the control strategy corresponding to the high-power segment includes: setting the filament current value to be less than 20% of the rated filament current, and executing the corresponding magnetic field current control strategy and power control strategy.

6. The power output method based on filament current and magnetic field current according to any one of claims 1 to 5, characterized in that: Execute the filament current control strategy, including the following steps: Generate reference value of filament current; Collect the real-time filament current of the magnetron and compare it with the reference value of the filament current; Based on the comparison result, a first control instruction is output to adjust the filament current of the magnetron, thereby forming a closed-loop control of the filament current.

7. The power output method based on filament current and magnetic field current according to claim 6, characterized in that: The reference value of the filament current satisfies: ； Where, Indicates the reference value of the filament current; Indicates the reference value of the magnetic field current in the previous cycle; Target power K 3 is the correction factor constant; a is the filament current index; b is the magnetic field intensity index; K is the magnetron parameter and is a constant.

8. The power output method based on filament current and magnetic field current according to any one of claims 1 to 5, characterized in that: Executing the field current control strategy includes the following steps: Generate reference value of magnetic field current; Collect the real-time magnetic field current of the magnetron and compare it with the reference value of the magnetic field current; Based on the comparison result, a second control instruction is output to adjust the magnetic field current of the magnetron, thereby forming a closed-loop control of the magnetic field current.

9. The power output method based on filament current and magnetic field current according to claim 8, characterized in that: The reference value of the magnetic field current satisfies: ； Where, Indicates the reference value of the magnetic field current; Indicates the reference value of the filament current in the previous cycle; is the target power; K 3 is the correction factor constant; a is the filament current index; b is the magnetic field intensity index; K is the magnetron parameter and is a constant.

10. The power output method based on filament current and magnetic field current according to any one of claims 1 to 5, characterized in that: Executing the power control strategy includes the following steps: After the filament current control strategy and / or the magnetic field current control strategy are executed, the real-time power of the magnetron is collected and compared with the target power; Outputting correction values ​​of filament current and magnetic field current based on the comparison results; The real-time power of the magnetron, the correction amount of the filament current, and the correction amount of the field current are input into the next cycle.

11. The power output method based on filament current and magnetic field current according to claim 5, characterized in that: When the target power is greater than 0 and less than or equal to 30% of the rated power, the magnetron is in the low power segment; when the target power is greater than 30% and less than or equal to 70% of the rated power, the magnetron is in the medium power segment; when the target power is greater than 70% and less than or equal to 100% of the rated power, the magnetron is in the high power segment.

12. A power output device based on filament current and magnetic field current, characterized in that: The device comprises a magnetron and a microwave power supply for supplying power to the magnetron. The device further comprises a processor, wherein the processor is configured to execute the method according to any one of claims 1 to 11.

13. A power output system based on filament current and magnetic field current, characterized in that: include: A first processing unit is used to obtain a target power of the magnetron; and, for determining the power range of the magnetron based on the target power or the real-time power; and, for determining that all n cycles have been completed when the real-time power of the magnetron is within a set range, otherwise the first processing unit executes the next cycle; A control unit, configured to execute a corresponding control strategy based on the power interval, wherein the control strategy includes a filament current control strategy, a magnetic field current control strategy, and a power control strategy; Power sensor, used to collect the real-time power of the magnetron after executing the control strategy; The starting unit is used to restart the first processing unit, the control unit and the power sensor to execute the corresponding strategy after all cycles are completed if the deviation between the real-time power and the target power is greater than the set value and the duration exceeds the set time.

14. The power output system based on filament current and magnetic field current according to claim 13, characterized in that: The control unit comprises: A filament current controller, configured to generate a reference value of the filament current; and to collect the real-time filament current of the magnetron; a filament loop PID regulator, configured to compare the real-time filament current of the magnetron with a reference value of the filament current, and output a first control instruction based on the comparison result to adjust the filament current of the magnetron, thereby forming a closed-loop control of the filament current; A magnetic field current controller, configured to generate a reference value of the magnetic field current; and to acquire the real-time magnetic field current of the magnetron; A magnetic field loop PID regulator is used to compare the real-time magnetic field current of the magnetron with a reference value of the magnetic field current, and output a second control instruction based on the comparison result to adjust the magnetic field current of the magnetron, thereby forming a closed-loop control of the magnetic field current; The power PID regulator is used to compare the real-time power of the magnetron with the target power after the filament current control strategy and / or the magnetic field current control strategy are executed, and output the correction amount of the filament current and the magnetic field current based on the comparison result, and input the real-time power of the magnetron, the correction amount of the filament current and the correction amount of the magnetic field current into the next cycle.

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