High-power magnetron microwave source design method

Abstract

The invention discloses a high-power magnetron microwave source design method, and belongs to the technical field of microwaves. The advanced series-parallel switch circuit topology technology is adopted, an anode high-voltage power supply, a filament power supply, a control protection unit and the like are integrated, only a connecting port of a transition waveguide and a transmitting antenna is exposed, and the time for mounting the microwave generator is shortened. The stability and reliability of the magnetron are improved, and the service life of the magnetron is prolonged. The LED lamp has comprehensive protection functions of ignition protection, anode overvoltage and overcurrent protection, filament overcurrent and undercurrent protection and the like, has the characteristics of high reliability, safety, high efficiency, high stability, low EMI (Electro-Magnetic Interference) and the like, and has a state display function.

Description

Technical Field

[0001] The invention relates to the field of microwave technology, and in particular to a design method for a high-power magnetron type microwave source. Background Art

[0002] Microwave technology is widely used in communications, radar, medical equipment, industrial heating and scientific research. Microwave source is the key equipment used to generate microwave energy, usually composed of high-voltage power supply, microwave power source, waveguide system and heat dissipation system.

[0003] At present, commonly used microwave sources mainly generate microwave signals through magnetrons or solid-state power amplifiers, and use waveguide systems to transmit microwave energy. However, there are still the following problems:

[0004] Large power loss: The conversion efficiency between the coaxial line and the waveguide in the existing microwave source is low, and the conversion efficiency of the power supply part is low, resulting in a large amount of power loss.

[0005] Poor heat dissipation: The microwave source generates a lot of heat when working, especially at high power output. If the heat cannot be effectively dissipated, it will cause the equipment to overheat, affect the stability of the microwave power source, and even cause equipment damage.

[0006] Low power instability: When the magnetron is in the initial oscillation stage below 10% of the nominal power, the internal electron motion trajectory is poor and the oscillation is unstable, resulting in problems such as low output power efficiency, poor linearity, low output frequency and wide bandwidth.

[0007] Therefore, in response to the above problems, the existing technology urgently needs a microwave source system with high reliability, safety, high efficiency, high stability, low EMI, and better heat dissipation performance and a high-power magnetron microwave source with status display to meet the diverse needs in industry and scientific research. Summary of the invention

[0008] In order to solve the above problems, the present invention provides a design scheme for a microwave generator, which adopts advanced series-parallel switch circuit topology technology, integrates anode high-voltage power supply, filament power supply and control protection unit, and only exposes the connection port of transition waveguide and transmitting antenna, which shortens the time required for microwave generator installation. The stability and reliability of the magnetron are improved, and the working life of the magnetron is extended. It has comprehensive protection functions such as ignition protection, anode overvoltage and overcurrent protection, filament overcurrent and undercurrent protection, and has the characteristics of high reliability, safety, high efficiency, high stability, low EMI, and status display function.

[0009] The technical solution of the present invention is as follows:

[0010] A high-power magnetron microwave source design method is as follows:

[0011] The high-power magnetron microwave source includes a microwave power supply part and a microwave device part; the microwave power supply part includes a control protection circuit, an anode high-voltage power supply and a filament power supply, which are integrated and placed inside a metal box; the high-power magnetron microwave source can independently control the on / off and output control of the anode high-voltage power supply and the filament power supply, and the control protection circuit is controlled by a PLC controller; the microwave device part includes a magnetron, an electromagnet, a transition waveguide, an excitation cavity and a BJ22 waveguide output interface.

[0012] Furthermore, the power of the high-power magnetron microwave source is 3 kW.

[0013] Furthermore, the anode high-voltage power supply is a high-voltage switching power supply; the filament power supply is a low-voltage switching power supply, and the input and output of the filament power supply are high-voltage isolated; the anode high-voltage power supply and the filament power supply provide power for the magnetron and the filament respectively, and are connected to the PLC controller respectively through the power isolation sensor.

[0014] Furthermore, the BJ22 waveguide output interface of the microwave device part, as well as the heat dissipation fan and the transition waveguide are exposed outside the microwave device part, which shortens the time required for installation and debugging when using the microwave source.

[0015] Furthermore, the anode high-voltage power supply and the filament power supply are integrated and connected to the main power supply. The main power supply inputs three-phase four-wire 380V AC to the anode high-voltage power supply and the filament power supply. The maximum output of the anode high-voltage power supply is 5.5kV1000mA of anode current and a peak power of 5kW; the filament power supply provides a maximum filament current of 24A and a maximum filament voltage of 5.8V, which are continuously adjustable; the cooling fan is powered by a separate 220V AC input.

[0016] Furthermore, a touch screen is provided on the metal box of the microwave power supply part, and the on / off and output control of the anode high voltage power supply and the filament power supply are independently controlled by the touch screen. If a fault occurs during operation, there is a corresponding fault indication, and there is a fault reset button.

[0017] Furthermore, the microwave power supply part can control and adjust the anode high-voltage power supply through the RS485 communication control method, through the host computer test interface with the corresponding communication protocol, and read its working status in real time; the data storage function can record and store the power supply working status and system working parameters in real time.

[0018] Furthermore, the magnetron selected is an S-band 2-4GHz, 3KW fixed frequency continuous wave magnetron; the magnetron has a thoriated tungsten carbide cathode, a full metal-ceramic structure, a packaged magnetic circuit system, and forced air cooling, and has the characteristics of fast cathode heating, high efficiency, stability, and easy control of the product.

[0019] Furthermore, the anode high voltage power supply includes an AC contactor, a high voltage switching power supply, an anode voltmeter, an anode ammeter, and an anode current detection control circuit; wherein:

[0020] The AC contactor is controlled by a PLC controller to control the AC input of the high-voltage switching power supply;

[0021] The high-voltage switching power supply generates the anode voltage required by the magnetron, which is a DC negative high voltage with a small ripple factor;

[0022] The anode voltage meter is connected to the output terminal of the high-voltage switching power supply to visually display the anode voltage;

[0023] The anode ammeter is connected in series in the high-voltage circuit of the high-voltage switching power supply to visually display the anode voltage and current;

[0024] The anode current detection control circuit is used to detect overcurrent, and includes a current and quantity sensor, an A / D analog conversion circuit, and an overcurrent detection module connected in series; wherein the current and quantity sensor measures the anode current, the A / D analog conversion circuit performs analog-to-digital conversion on the anode current, the overcurrent detection module detects overcurrent, and the anode current detection control circuit inputs the detected anode current signal into the PLC controller.

[0025] Furthermore, the filament power supply includes an AC contactor, a filament switch power supply, a filament current detection control circuit, and a filament ammeter; wherein:

[0026] The AC contactor is controlled by the PLC controller to control the AC input of the filament switch power supply;

[0027] The filament switching power supply is used to generate the filament current required by the magnetron;

[0028] The filament current detection control circuit is used to monitor the filament current, including an AC power sensor to complete the detection of the filament current, and an A / D analog conversion circuit to perform analog-to-digital conversion on the filament current. The filament current detection control circuit sends the detected filament current digital signal to the PLC controller for processing, and controls the filament current according to the size of the anode current;

[0029] The filament ammeter is connected to the input end of the filament switching power supply to indirectly display the magnetron filament current.

[0030] The present invention provides a design scheme of a microwave source to solve the problems of poor heat dissipation, low conversion efficiency and excessive volume in the prior art. The microwave source includes a microwave power supply, a magnetron, a transition waveguide and a fan for heat dissipation, which can effectively improve the stability of microwave power and heat dissipation performance.

[0031] Beneficial effects of the present invention:

[0032] 1. The present invention replaces the bulky transformer with a switching power supply, reduces the volume and weight, integrates the power supply and microwave devices together, and only the connection ports of the heat dissipation fan, transition waveguide and transmitting antenna are exposed, thereby reducing the installation and debugging time.

[0033] 2. High-frequency switching power supply (50kHz) is used in the anode high-voltage power supply and filament power supply. Since the switching power supply has a high power conversion efficiency (≥80%), the conversion efficiency of the microwave source's electrical energy into microwave energy is greatly improved. The ripple factor of the DC power supply is reduced, and the stability, reliability and service life of the microwave source are improved.

[0034] 4. Improve the stability and reliability of the magnetron and extend the working life of the magnetron. It has comprehensive protection functions such as ignition protection, anode overvoltage and overcurrent protection, filament overcurrent and undercurrent protection, and has high reliability, safety, high efficiency, high stability, low EMI and other characteristics and status display. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the appearance diagram of the microwave source;

[0036] Figure 2 It is the schematic diagram of microwave source;

[0037] Figure 3 This is the appearance diagram of the microwave power supply;

[0038] Figure 4 This is a brief diagram of the composition of a microwave power supply;

[0039] Figure 5 It is the schematic diagram of the anode high voltage power supply;

[0040] Figure 6 It is the schematic diagram of the filament power supply;

[0041] Figure 7 Filament current versus anode current curve. DETAILED DESCRIPTION

[0042] In order to make the purpose, technology and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0043] 1. The magnetron microwave source includes a microwave power supply part and a microwave device part, such as Figure 1 shown.

[0044] 1.1 The microwave power supply part includes filament power supply, anode high voltage power supply and control protection circuit, etc. The microwave device part includes 3KW magnetron, electromagnet, transition waveguide, excitation cavity and BJ22 waveguide output interface. Among them, 3KW continuous wave magnetron, such as Figure 2Working temperature 0~40℃, storage temperature -10~50℃, humidity 95% without condensation, altitude less than 3000m.

[0045] 1.2 The microwave power supply has built-in filament power supply, anode high voltage power supply and control protection circuit, etc. The overall dimensions of the microwave power supply (excluding the panel handle and exposed connectors): 491mm*143mm*532mm±2mm (width*height*depth), such as Figure 3 As shown, the brief composition is as follows Figure 4 shown.

[0046] 1.3 The microwave power supply part includes a control protection circuit, an anode high voltage power supply, and a filament power supply. The control protection circuit is controlled by a PLC controller. Among them, the anode high voltage power supply provides power for the magnetron, and the filament power supply converts AC power into adjustable DC power, which is converted into an isolated AC voltage to generate the filament current required for the magnetron.

[0047] 1.4 Main performance indicators

[0048] High-power magnetron microwave source operating frequency: 2400~2500MHz;

[0049] High-power magnetron microwave source output power: ≧2.7kW;

[0050] The actual working anode voltage of the anode high voltage power supply: 5.1kV;

[0051] The actual working anode current of the anode high voltage power supply: 0.84A;

[0052] Filament preheating current: 21A;

[0053] Preheating time: ≧60s.

[0054] 2 Anode high voltage power supply:

[0055] 2.1 As Figure 5 As shown, the anode high voltage power supply includes: AC contactor, high-frequency and high-stability anode high voltage switching power supply (switching frequency 50kHz, ripple <1%), anode voltmeter, anode ammeter, anode current detection control circuit, etc. Among them, the AC contactor is controlled by the PLC controller to control the AC input of the high voltage switching power supply; the high voltage switching power supply generates the anode voltage required by the magnetron, which is a DC negative high voltage with a small ripple factor (<1%);

[0056] 2.2 Anode voltage meter, connected to the output terminal of the high-voltage switching power supply, used to visually display the anode voltage;

[0057] 2.3 Anode ammeter, connected in series in the high-voltage circuit of the high-voltage switching power supply, is used to visually display the anode voltage and current;

[0058] 2.4 The anode current detection control circuit is used to detect overcurrent, including a series current and quantity sensor, an A / D analog conversion circuit, an overcurrent detection module, etc.; wherein the current and quantity sensor measures the anode current, the A / D analog conversion circuit performs analog-to-digital conversion on the anode current, the overcurrent detection module detects overcurrent, and the anode current detection control circuit inputs the detected anode current signal to the PLC controller to timely adjust the working state of the magnetron or shut down the high voltage.

[0059] 2.5 Anode high voltage output:

[0060] Output voltage: DC-5.8kV (voltage adjustment resolution 0.01KV); Output current: DC10~1000mA continuously adjustable; Voltage ripple: <1%; Power stability (30 minutes after startup): less than 1% for 4 hours of continuous operation; Load adjustment rate: <2%; Anode high voltage power supply has anti-sparking function, and the power supply will not be damaged in case of short circuit and sparking;

[0061] 3. Filament power supply:

[0062] 3.1 As Figure 6 As shown, the filament power supply includes an AC contactor, a filament switching power supply with high frequency stability (switching frequency 50kHz, ripple <1.5%), a filament current detection control circuit, a filament ammeter, etc.;

[0063] 3.2 The AC contactor is controlled by the PLC controller to control the AC input of the filament switch power supply;

[0064] 3.3 Filament switching power supply, switching frequency 50kHz, voltage ripple <1.5%, generates the filament current required by the magnetron;

[0065] 3.4 The filament current detection control circuit is used to monitor the filament current, including an AC electrical quantity sensor to complete the detection of the filament current, and an A / D analog conversion circuit to perform analog-to-digital conversion on the filament current. The filament current detection control circuit sends the detected filament current digital signal to the PLC controller for processing, and controls the filament current according to the size of the anode current.

[0066] 3.5 Filament ammeter, connected to the input end of the filament switching power supply, indirectly displays the magnetron filament current.

[0067] 3.6 Filament power output, output voltage: DC2~5.5V; output current: DC2~24A continuously adjustable; output end withstand voltage to input and housing greater than DC 8kV; current stability: less than 5% for 4 hours of continuous operation;

[0068] 4 Magnetrons are S-band (2-4GHz) 3KW fixed frequency continuous wave magnetrons.

[0069] 4.1 The tube has a thoriated tungsten carbide cathode, a full metal-ceramic structure, a packaged magnetic circuit system, and forced air cooling. It has the characteristics of fast cathode heating, high efficiency, stability, and easy control. It is powered by the above power supply. The curve of the magnetron filament current changing with the anode current is as follows Figure 7 shown.

[0070] 4.2 Main technical indicators

[0071] Frequency: (2400~2500)MHz; Output power: ≧3kW; Anode voltage: ≦5.3kV; Anode current: 0.84A; Filament preheating voltage: 4.6±0.2V; Filament preheating current: 21A; Preheating time: ≧60s.

[0072] 5. Protection and status display

[0073] 5.1 Fault protection: power supply fault (filament undercurrent, filament overcurrent, anode overvoltage, anode overcurrent, ignition fault) protection; external fault (magnetron overtemperature protection, water flow protection (both protections are connected to the external passive switch quantity of the power supply)) protection;

[0074] 5.2 Status display: The touch screen displays the working parameters of each level of power supply (filament current, anode voltage, anode current) and each level of fault.

[0075] 6. Equipment electrical wiring

[0076] 6.1 Power supply wiring:

[0077] Connect to the terminal block through the high-voltage power supply (3kW type), and connect the 1st to 4th pins of the terminal block sockets to the A, B, C and neutral line N of AC380V respectively (the power supply line must use a cable with a wire diameter of not less than 3*2.5+1*1.5mm2).

[0078] 6.2 Safe wiring:

[0079] Connect the ground to the safety ground through the stud marked on the rear panel of the high-voltage power supply to ensure reliable connection (the ground wire must be a wire with a diameter of not less than 4mm2);

[0080] 6.3 High voltage wiring:

[0081] The anode high voltage and the filament are connected through the two white high voltage wires of "high voltage output" on the rear panel of the high voltage power supply;

[0082] 6.4 High voltage ground connection:

[0083] Connect to the magnetron through the high voltage ground terminal on the rear panel of the high voltage power supply. (The output ground connection wire must be a wire with a diameter of no less than 4mm2).

Claims

1. A method for designing a high-power magnetron microwave source, characterized in that: The details are as follows: The high-power magnetron microwave source includes a microwave power supply part and a microwave device part; the microwave power supply part includes a control protection circuit, an anode high-voltage power supply and a filament power supply, which are integrated and placed inside a metal box; the high-power magnetron microwave source can independently control the on / off and output control of the anode high-voltage power supply and the filament power supply, and the control protection circuit is controlled by a PLC controller; the microwave device part includes a magnetron, an electromagnet, a transition waveguide, an excitation cavity and a BJ22 waveguide output interface.

2. A high-power magnetron microwave source design method according to claim 1, characterized in that: The power of the high-power magnetron microwave source is 3kW.

3. A high-power magnetron microwave source design method according to claim 1, characterized in that: The anode high-voltage power supply is a high-voltage switching power supply; the filament power supply is a low-voltage switching power supply, and the input and output of the filament power supply are high-voltage isolated; the anode high-voltage power supply and the filament power supply provide power for the magnetron and the filament respectively, and are connected to the PLC controller through a power isolation sensor.

4. A high-power magnetron microwave source design method according to claim 1, characterized in that: The BJ22 waveguide output interface of the microwave device part, as well as the heat dissipation fan and the transition waveguide are exposed outside the microwave device part, which shortens the time required for installation and debugging when using the microwave source.

5. A high-power magnetron microwave source design method according to claim 1, characterized in that: The anode high-voltage power supply and the filament power supply are integrated and connected to the main power supply. The main power supply inputs three-phase four-wire 380V AC to the anode high-voltage power supply and the filament power supply. The maximum output of the anode high-voltage power supply is 5.5kV1000mA anode current and peak power of 5kW; the filament power supply provides a maximum filament current of 24A and a maximum filament voltage of 5.8V, which are continuously adjustable; the cooling fan is powered by a separate 220V AC input.

6. A high-power magnetron microwave source design method according to claim 1, characterized in that: A touch screen is provided on the metal box of the microwave power supply part, through which the anode high voltage power supply and the filament power supply are independently controlled to switch on and off and output control. If a fault occurs during operation, there will be a corresponding fault indication and a fault reset button.

7. A high-power magnetron microwave source design method according to claim 1, characterized in that: The microwave power supply part can control and adjust the anode high-voltage power supply through the RS485 communication control method, and read its working status in real time through the host computer test interface with the corresponding communication protocol; the data storage function can record and store the power supply working status and system working parameters in real time.

8. A high-power magnetron microwave source design method according to claim 1, characterized in that: The magnetron selected is an S-band 2-4GHz, 3KW fixed frequency continuous wave magnetron; the magnetron has a thoriated tungsten carbide cathode, a full metal-ceramic structure, a packaged magnetic circuit system, and forced air cooling. It has the characteristics of fast cathode heating, high efficiency, stability, and easy control of the product.

9. A high-power magnetron microwave source design method according to claim 1, characterized in that: The anode high voltage power supply includes an AC contactor, a high voltage switching power supply, an anode voltmeter, an anode ammeter, and an anode current detection control circuit; wherein: The AC contactor is controlled by a PLC controller to control the AC input of the high-voltage switching power supply; The high-voltage switching power supply generates the anode voltage required by the magnetron, which is a DC negative high voltage with a small ripple factor; The anode voltage meter is connected to the output terminal of the high-voltage switching power supply to visually display the anode voltage; The anode ammeter is connected in series in the high-voltage circuit of the high-voltage switching power supply to visually display the anode voltage and current; The anode current detection control circuit is used to detect overcurrent, and includes a current and quantity sensor, an A / D analog conversion circuit, and an overcurrent detection module connected in series; wherein the current and quantity sensor measures the anode current, the A / D analog conversion circuit performs analog-to-digital conversion on the anode current, the overcurrent detection module detects overcurrent, and the anode current detection control circuit inputs the detected anode current signal into the PLC controller.

10. A high-power magnetron microwave source design method according to claim 1, characterized in that: The filament power supply includes an AC contactor, a filament switch power supply, a filament current detection control circuit, and a filament ammeter; wherein: The AC contactor is controlled by the PLC controller to control the AC input of the filament switch power supply; The filament switching power supply is used to generate the filament current required by the magnetron; The filament current detection control circuit is used to monitor the filament current, including an AC power sensor to complete the detection of the filament current, and an A / D analog conversion circuit to perform analog-to-digital conversion on the filament current. The filament current detection control circuit sends the detected filament current digital signal to the PLC controller for processing, and controls the filament current according to the size of the anode current; The filament ammeter is connected to the input end of the filament switching power supply to indirectly display the magnetron filament current.

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