A method and circuit for controlling a single transformer cathode power supply for a heat recovery electron gun

Abstract

The application discloses a heat conduction type electron gun single transformer cathode power supply control method and a control circuit, and belongs to the technical field of electron beam processing equipment. The method comprises the following steps: in a first stage, a power supply direct current is gradually increased until a filament current reaches a first preset threshold value, and a first adjusting parameter is recorded; in a second stage, the filament current at the end of the first stage is taken as a given starting point, the filament current is gradually increased until a bombardment current reaches a second preset threshold value, and a second adjusting parameter is recorded; in a third stage, the second adjusting parameter is taken as a starting point to gradually increase a bombardment power until the bombardment power reaches a given value, and a third adjusting parameter is recorded; and in a fourth stage, a preset power given value is taken as a target, and the third adjusting parameter is taken as a bias to stably adjust and control the bombardment power in a closed loop. The application is suitable for a cathode power supply adopting a single transformer, and can effectively control the output power of the bombardment power supply.

Description

Technical Field

[0001] This invention relates to the field of electron beam processing equipment technology, and more specifically to a method and control circuit for controlling the cathode power supply of an interthermal electron gun with a single transformer. Background Technology

[0002] Indirect-heated electron gun cathode power supplies require two types of power sources: a filament power supply and a bombardment power supply. The ultimate goal is to control the heating power of the cathode, i.e., to control the output power of the bombardment power supply. Conventional control methods include:

[0003] 1) Constant current control of filament current and constant current control of bombardment power supply; changing the bombardment voltage changes the bombardment power. 2) Constant voltage control of the bombardment power supply, changing the filament current to control the bombardment current; The aforementioned control method dictates that the cathode power supply must operate in cooperation with two independent power sources. Since the filament power supply and bombardment power supply are relatively small, while the cathode power supply operates at a high unit voltage, high-voltage insulation is required between the primary and secondary windings of the isolation transformer. Therefore, the transformers for the filament and bombardment power supplies are constrained by the high-voltage insulation structure, resulting in significantly larger geometric dimensions compared to conventional transformers.

[0004] In certain specialized applications, such as aerospace and deep-sea environments, electron beam processing technology offers unique advantages, but it also imposes stringent requirements on the equipment's geometry, weight, and energy efficiency. To address this, a single transformer is proposed for the filament power supply and bombardment power supply in an indirect-heated electron gun cathode power supply, achieving a "slimming down" effect on the equipment. However, when a single transformer is used for the cathode power supply, the primary input of the transformer changes, simultaneously altering the filament current, bombardment voltage, and bombardment current. That is, an increase in the primary input directly leads to an increase in filament current and bombardment voltage, while an increase in filament current and bombardment voltage both lead to an increase in bombardment current, and vice versa.

[0005] Therefore, when a single transformer is used in the cathode power supply, there is a complex nonlinear relationship between the input of the transformer and the output power of the bombardment power supply. Conventional control methods for the cathode power supply are no longer adequate for its multi-mode operation, and new control methods need to be explored to achieve effective control of the output power of the bombardment power supply. Summary of the Invention

[0006] In view of the above problems, the present invention proposes a method and control circuit for controlling the cathode power supply of an interthermal electron gun single transformer, so as to overcome the above problems or at least partially solve the above problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, embodiments of the present invention provide a method for controlling the cathode power supply of an interthermal electron gun single transformer, which outputs adjustment parameters through a multi-stage adjustment process, wherein the adjustment parameters are the inverter frequency of the LLC inverter in the converter, used to change the excitation state of the primary side of the single transformer by adjusting the output of the converter; the multi-stage adjustment process includes: In the first stage, based on the gradually increasing DC power supply output adjustment parameter, when the filament current rises and reaches the first preset threshold, the current adjustment parameter f is recorded as the first adjustment parameter. And switch to the second phase; In the second stage, taking the ramp function starting from the filament current feedback value at the end of the first stage as a given, using the filament current as feedback and the first adjustment parameter as a bias, the filament current is gradually increased. When the bombardment current reaches the second preset threshold, the current adjustment parameter f is recorded as the second adjustment parameter. And switch to the third stage; In the third stage, the slope function value decreasing from the second adjustment parameter is used as the adjustment parameter to control the bombardment power to gradually increase. When the bombardment power reaches a given value, the current adjustment parameter f is recorded as the third adjustment parameter. And switch to the fourth stage; In the fourth stage, with a preset power setpoint as the target, the third adjustment parameter... As a bias, the bombardment power is adjusted using closed-loop feedback to maintain its stability until the operation ends.

[0008] Preferably, the parameter for adjusting the output based on the power supply DC current includes: Using the ramp function of the power supply DC current as a given, the digital sampling signal of the power supply DC current as feedback, and the upper limit of the adjustment parameter as a bias, the first PID controller is started to output the adjustment parameter.

[0009] Preferably, the first preset threshold is a preset minimum filament current.

[0010] Preferably, the second preset threshold is a preset minimum bombardment current.

[0011] Secondly, embodiments of the present invention provide an interthermal electron gun single-transformer cathode power supply control circuit, comprising: Power supply; The converter has its input terminal connected to the power supply. The transformer has its primary side connected to the output terminal of the converter, and its secondary side connected to the filament power supply and the bombardment power supply, respectively. The positive and negative output terminals of the filament power supply are connected to the positive and negative poles of the filament, respectively. The positive output terminal of the bombardment power supply is connected to the cathode of the electron gun, and the negative output terminal is connected to the negative output terminal of the filament power supply as the first potential reference terminal (C terminal) to form a bombardment voltage between the filament and the cathode. The sampling unit is connected to the output sampling terminal of the filament power supply and the output sampling terminal of the bombardment power supply through a transmitter, respectively, to synchronously collect filament voltage, filament current, bombardment voltage and bombardment current, convert them into digital signals and output them to the adjustment unit. The regulating unit is used to receive the sampling signal, execute the interthermal electron gun single transformer cathode power supply control method as described in any of the above, determine the regulating parameters, and output a control signal to the converter according to the regulating parameters to regulate the output voltage of the transformer.

[0012] Preferably, the converter is a half-wave LLC inverter circuit structure, including a DC input terminal for receiving the DC voltage from the power supply; wherein, Capacitors C21 and C22 are connected in series between the positive and negative terminals of the DC input terminal; and switching transistors V21 and V22 are connected in series between the positive and negative terminals of the DC input terminal. The control terminal of switching transistor V21 is connected to a first drive signal, and the control terminal of switching transistor V22 is connected to a second drive signal. The common node of the switching transistors V21 and V22 is connected to the common node of the capacitors C21 and C22 via inductor L21 and capacitor C23, thus forming the output terminal of the converter. The converter also includes a voltage divider sampling network and a current sampling resistor for acquiring the DC voltage and current supplied. Preferably, the half-wave LLC inverter circuit in the converter adopts a frequency conversion voltage regulation mode. The output voltage of the LLC inverter circuit is low when the inverter frequency is high, and vice versa. The highest inverter frequency is set to correspond to the highest allowed inverter frequency of the LLC inverter, and the lowest inverter frequency is set to correspond to the maximum allowed output power of the power supply.

[0013] Preferably, the transmitter includes at least one transmission branch, the transmission branch comprising: The first input terminal is connected to the inverting input terminal of operational amplifier A71 via resistor R71. The non-inverting input terminal of operational amplifier A71 is connected to the first potential reference terminal. Resistor R72 is connected between the output terminal and the inverting input terminal of the operational amplifier. The output terminal of operational amplifier A71 serves as the first output terminal. The second input terminal is directly connected to the first potential reference terminal; The third input terminal is connected to the non-inverting input terminal of operational amplifier A72 via resistor R73. The non-inverting input terminal of operational amplifier A72 is also connected to the first potential reference terminal via resistor R75. Resistor R76 is connected between the output terminal and the inverting input terminal of operational amplifier A72. The inverting input terminal of operational amplifier A72 is connected to the first potential reference terminal via resistor R74. The resistance values ​​of resistors R73 and R74 are equal, and the resistance values ​​of resistors R75 and R76 are equal. The output terminal of operational amplifier A72 serves as the second output terminal.

[0014] Preferably, the secondary side of the transformer is also connected to an auxiliary power supply to convert AC power into ±5V and +V DC power to power the active functional devices in the transmitter and the sampling unit.

[0015] Preferably, the transmitter circuit includes two transmission branches. The first input terminal to the third input terminal of the first transmission branch are respectively connected to the current sampling output terminal, the first potential reference terminal, and the voltage sampling output terminal of the filament power supply, and are used to convert the filament current signal and the filament voltage signal into the corresponding signals required by the sampling unit. The first input terminal to the third input terminal of the second transmission branch are respectively connected to the current sampling output terminal, the first potential reference terminal, and the voltage sampling output terminal of the bombardment power supply, and are used to convert the bombardment current signal and the bombardment voltage signal into the corresponding signals required by the sampling unit.

[0016] Preferably, the sampling unit includes: The digital processor 82A is connected to the transmitter via an A / D converter A81 and is connected to the regulating unit via an optical fiber through a serial interface A83. The digital processor 82A controls the A / D converter A81 to acquire digital signals of filament voltage, filament current, bombardment voltage, and bombardment current, and enables data exchange with the digital processor A92 of the adjustment unit.

[0017] Preferably, the adjustment unit includes: The digital processor A92 is configured to determine adjustment parameters based on the sampled signal according to the interthermal electron gun single transformer cathode power supply control method as described in any of the preceding claims; The digital processor A92 is connected to the sampling unit via serial interface A91, to the host computer via serial interface A93, and sequentially connected to the DC voltage and current sampling output terminals of the power supply in the converter via A / D converter A94 and isolation transmitter A95; and the adjustment parameters are converted into drive signals and input to the converter via driver A96.

[0018] Preferably, the adjustment unit needs to be externally supplied with positive power supplies V1, V2 and V3, wherein the common terminal of the positive power supplies V1 and V2 serves as the third potential reference terminal (O terminal), and the negative terminal of the positive power supply V3 is connected to the second potential reference terminal (N terminal) to supply power to each active functional device in the adjustment unit.

[0019] Preferably, the isolation transmitter A95 includes at least one isolation transmission branch, which includes: Linear isolator A951 and operational amplifier A953; The positive input terminal of the linear isolator A951 serves as the input terminal of the isolation transmitter branch. The negative input terminal of the linear isolator A951 is connected to a second potential reference terminal. The positive output terminal of the linear isolator A951 is connected to the non-inverting input terminal of the operational amplifier A953 via resistor R91. The non-inverting input terminal of the operational amplifier A953 is also connected to a third potential reference terminal via resistor R93. The negative output terminal of the linear isolator A951 is connected to the inverting input terminal of the operational amplifier A953 via resistor R92. A resistor R94 is connected between the output terminal and the inverting input terminal of the operational amplifier A953. The resistance values ​​of resistors R91 and R92 are equal, and the resistance values ​​of resistors R93 and R94 are equal. The output terminal of the operational amplifier A953 serves as the output terminal of the isolation transmitter branch. Preferably, the isolation transmitter A95 circuit includes two isolation transmission branches. The input terminal of the first isolation transmission branch is connected to the voltage sampling output terminal of the DC power supply of the converter, and the input terminal of the second isolation transmission branch is connected to the current sampling output terminal of the DC power supply of the converter. This is used to convert the voltage signal and current signal of the DC power supply into the corresponding signals required by the A / D converter 94.

[0020] Preferably, the digital processor A92 outputs adjustment parameters f in the form of drive signals g1 and g2, and the drive signals g1 and g2 are isolated and amplified by the driver A96 to output a drive voltage. and .

[0021] Preferably, the driver A96 includes two isolation amplification branches A961 and A962, wherein the input signal of the first isolation amplification branch A961 is g1, and the output signal is g2. The input signal of the second isolation amplifier branch A962 is g2, and the output signal is g2. .

[0022] This invention provides a method and circuit for controlling the cathode power supply of an interthermal electron gun single transformer; compared with the prior art, the beneficial effects include at least: In the indirect-heated electron gun cathode power supply, the filament power supply and the bombardment power supply share a single transformer, thereby achieving a "slimming down" of the equipment power supply and improving the overall power conversion efficiency. The auxiliary power required for the high-voltage side control circuit is provided autonomously by the cathode power supply transformer. In the initial startup phase, the DC supply current from the low-voltage side is used as the feedback signal to prevent the closed-loop control system from "running out of control" before the auxiliary power supply is established. In the bombardment power control, the bombardment power is first gradually increased to the target value through open-loop control to determine the bias of the bombardment power closed-loop control loop. Adjust the parameter f around When the surrounding environment changes, the regulator operates in a small-signal regulation state, overcoming the risk of "running out of control" when the regulator of a nonlinear system operates in a large-signal regulation state; through bias setting, each operating mode can transition smoothly. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the adjustment process of the adjustment parameter provided in the embodiment of the present invention; Figure 2 This is a block diagram of the mode transition process for adjusting the adjustment parameters provided in this embodiment of the invention; Figure 3 This is a schematic diagram of the interthermal electron gun single transformer cathode power supply control circuit provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the power supply circuit provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of a converter circuit provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of a transformer circuit provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the filament power supply circuit provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the bombardment power supply circuit provided in an embodiment of the present invention; Figure 9 This is a schematic diagram of the auxiliary power supply circuit provided in an embodiment of the present invention; Figure 10 This is a schematic diagram of the transmitter circuit provided in an embodiment of the present invention; Figure 11 This is a schematic diagram of the sampling unit structure provided in an embodiment of the present invention; Figure 12 This is a schematic diagram of the adjustment unit structure provided in an embodiment of the present invention; Figure 13 This is a schematic diagram of the isolation transmitter circuit provided in an embodiment of the present invention; Figure 14 This is a driving signal waveform diagram provided in an embodiment of the present invention; Figure 15 This is a schematic diagram of the driver circuit provided in an embodiment of the present invention.

[0025] Figure 3 middle: 1-Power supply; 2-Converter; 3-Transformer; 4-Filament power supply; 5-Impact power supply; 6-Auxiliary power supply; 7-Transmitter; 8-Sampling unit; 9-Fiber optic cable; 10-Regulation unit; 11-Host computer. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This invention discloses a method and control circuit for controlling the cathode power supply of an interthermal electron gun with a single transformer. For ease of description, the following table first provides the meanings of the parameters during the signal transformation process:

[0028] Example 1: This embodiment provides a method for controlling the cathode power supply of an interthermal electron gun single transformer, which includes at least a filament preheating stage and a cathode heating stage. The working principle is as follows: the filament power supply heats the filament, and when the filament is heated to a certain temperature, it emits working electrons; the electrons emitted by the filament are subjected to a bombardment voltage... Accelerated, it flies towards the cathode to form a bombardment current. The output power of the bombardment power supply P (P= × This refers to cathode heating, which allows the cathode to emit more electrons when heated.

[0029] In this embodiment, the filament power supply and the bombardment power supply share the same adjustment parameter controlling the same transformer. The adjustment parameter is the inverter frequency of the LLC inverter in the converter, which is used to change the excitation state of the primary side of the single transformer by adjusting the output of the converter. The single transformer is a single transformer in the interthermal electron gun cathode power supply, which supplies power to both the filament power supply and the bombardment power supply.

[0030] The adjustment parameters are output sequentially through the following multi-stage adjustment process: In the first stage, the DC power supply is adjusted based on the output parameter of the supply DC current. The supply DC current is gradually increased from 0. When the filament current rises and reaches the first preset threshold, the current adjustment parameter f is recorded as the first adjustment parameter. And switch to the second phase; In the second stage, starting from the filament current feedback value at the end of the first stage, and using the filament current as feedback and the first adjustment parameter as bias, the filament current is gradually increased. When the bombardment current reaches the second preset threshold, the current adjustment parameter f is recorded as the second adjustment parameter. And switch to the third stage; In the third stage, the slope function value decreasing from the second adjustment parameter is used as the adjustment parameter to control the bombardment power to gradually increase. When the bombardment power reaches a given value, the current adjustment parameter f is recorded as the third adjustment parameter. And switch to the fourth stage; In the fourth stage, with a preset power setpoint as the target, the third adjustment parameter... As a bias, the bombardment power is adjusted using closed-loop feedback to maintain its stability until the operation ends.

[0031] In one alternative implementation, the adjustment process of the adjustment parameter is as follows: Figure 1 and Figure 2 As shown; 1. The auxiliary power supply establishes its mode, which is the initial stage of the cathode power supply. First, terminals 1 and 5 of switch K are connected to adjust the output parameters based on the supply DC current. For example, this is achieved using a ramp function of the supply DC current that starts from 0 and increases. Given a value, and a sampled digital signal with DC supply current. Feedback signal activates controller PID1, the control loop operates, and outputs adjustment value f1 to further adjust the upper limit of the parameter. For bias, output adjustment parameter Until the filament current Reaching the predetermined minimum value ,Right now At this point, the operating mode ends, and the sampled digital signals of the adjustment parameter f and the filament current are recorded. And respectively defined as the first adjustment amount. and minimum filament current setpoint It then enters the filament current regulation mode.

[0032] 2. Filament current adjustment mode: In this mode, PID1 controller is turned off, terminals 2 and 5 of switch K are connected, and the PID2 control loop is started. This loop operates based on the minimum filament current setpoint. The rising slope function Given a value, the digital signal of the filament current is sampled. As the feedback quantity, the output adjustment quantity f2 is further used as the first adjustment quantity. As a bias, the adjustment parameters are obtained. Until the bombardment current Reaching the predetermined minimum value ,Right now When this working mode ends, record f at this time and define it as the second adjustment parameter. And enter the bias value of the bombardment power control loop to determine the impact power control loop. Modality.

[0033] 3. Determine the bias value of the bombardment power control loop. In this modal state, the PID2 controller is turned off, and terminals 3 and 5 of switch K are connected to start from... The slope function that begins to descend Directly used as an adjustment parameter Until the bombardment power reaches a given value, that is At this point, the working mode ends, the adjustment parameter f is recorded, and it is defined as the third adjustment parameter. It then enters the bombardment power stabilization mode.

[0034] 4. For the bombardment power stabilization mode, connect terminals 4 and 5 of switch K to start the PID3 control loop. As the bias value, with For a given value, with As the feedback quantity, the output adjustment quantity f3 is further adjusted to a third adjustment quantity. As a bias, the adjustment parameters are obtained. Until the work is finished.

[0035] Example 2: This embodiment provides a control circuit for an interthermal electron gun single-transformer cathode power supply, such as... Figure 3 ,include: Power supply 1; Converter 2, with its input terminal connected to power supply 1; The transformer 3 has its primary side connected to the output terminal of the converter 2, and its secondary side connected to the filament power supply 4 and the bombardment power supply 5, respectively. Preferably, the secondary side of the transformer is also connected to an auxiliary power supply, which is used to convert AC power into ±5V and +V DC power to power the active functional devices in the subsequent transmitter and sampling unit. The positive and negative output terminals of the filament power supply 4 are connected to the positive and negative poles of the electron gun filament. The positive output terminal of the bombardment power supply 5 is connected to the cathode of the electron gun. The negative output terminal of the bombardment power supply 5 is connected to the negative output terminal of the filament power supply 4 as the first potential reference terminal (C terminal) to form a bombardment voltage between the filament and the cathode. Sampling unit 8 is connected to the output sampling terminal of filament power supply 4 and the output sampling terminal of bombardment power supply 5 via transmitter 7, respectively, for synchronously acquiring filament voltage. Filament current Bombardment voltage and bombardment current They are converted into digital signals respectively. The output is then sent to the adjustment unit 10; Adjustment unit 10 is used to receive sampling signals, execute the interthermal electron gun single transformer cathode power supply control method as described in any of the preceding claims, determine adjustment parameter f, and output control signals according to the adjustment parameter f. , The voltage is supplied to the converter 2 to adjust the output voltage AC2 of the transformer 3.

[0036] In one alternative implementation, the circuit diagram of power supply 1 is as follows: Figure 4 As shown, it includes a rectifier bridge ZL11 and a filter capacitor C11, used to receive the power frequency AC current AC1 and convert it into an uncontrollable DC supply voltage. .

[0037] In one alternative implementation, converter 2 is used to convert the uncontrollable supply DC voltage. It is converted into controllable alternating current AC2. In this embodiment, converter 2 is a half-wave LLC inverter circuit structure, and the circuit diagram is shown below. Figure 5 As shown; it includes a DC input terminal for receiving the supplied DC voltage. ;in, Capacitors C21 and C22 are connected in series between the positive and negative terminals of the DC input terminal; and switching transistors V21 and V22 are connected in series between the positive and negative terminals of the DC input terminal. The control terminal of switching transistor V21 is connected to a first drive signal, and the control terminal of switching transistor V22 is connected to a second drive signal. The first and second drive signals are generated by the adjustment unit 10, and the specific process is described in the description of the adjustment unit 10. Furthermore, the common node of switching transistors V21 and V22 is connected to the common node of capacitors C21 and C22 via inductor L21 and capacitor C23, thus forming the output terminal AC2 of the converter.

[0038] In this embodiment, the converter 2 further includes a voltage divider sampling network and a current sampling resistor for acquiring the DC power supply voltage and current. The voltage divider sampling network includes resistors R22 and R23 connected in series between the positive and negative terminals of the DC input; the current sampling resistor includes resistor R21 connected in series in the busbar, as detailed below. Figure 5 The DC power supply current is used to power the resistor R21. The DC power supply voltage is based on the voltage across resistor R22. .

[0039] In some implementation schemes, the half-wave LLC inverter circuit in the converter 2 adopts a frequency conversion voltage regulation mode; the LLC inverter circuit has a high inverter frequency and a low output voltage, and vice versa; the highest inverter frequency is set to correspond to the highest allowed inverter frequency of the LLC inverter, and the lowest inverter frequency is set to correspond to the maximum output power.

[0040] In one alternative implementation, the circuit diagram of transformer 3 is as follows: Figure 6 As shown, it includes three sets of secondary windings, which output AC4, AC5 and AC6 respectively to power the filament power supply 4, the bombardment power supply 5 and the auxiliary power supply 6.

[0041] In one alternative implementation, the filament power supply 4 is used to rectify the alternating current AC4 into a filament voltage. Circuits such as Figure 7 As shown, it consists of diode D41, diode D42, and filter capacitor C41, with resistor R41 holding the filament current. The sampling resistor ultimately outputs the filament current. and filament voltage .

[0042] In one alternative implementation, the bombardment power supply 5 is used to rectify the alternating current AC5 into a bombardment voltage. Circuits such as Figure 8 As shown; it consists of a rectifier bridge ZL51 and a filter capacitor C51, where resistor R51 is the charge current. The sampling resistors, resistors R52 and R53, are for the impact voltage. The voltage divider resistors ultimately output the bombardment current. and bombardment voltage .

[0043] In one alternative implementation, auxiliary power supply 6 is used to convert AC power AC6 into DC power +V and ±5V regulated power, as shown in the circuit. Figure 9 As shown, it consists of a rectifier bridge ZL61, filter capacitors C61, C62, C63, and C64, and voltage regulator integrated circuits A61 and A62.

[0044] In one optional implementation, the transmitter 7 is used to convert the sampled signal into a voltage signal that can be received by the A / D converter; in this embodiment, at least one transmitter branch is included; the specific structure is as follows. Figure 10 As shown; The first input terminal 1 is connected to the inverting input terminal of the operational amplifier A71 via resistor R71. The non-inverting input terminal of the operational amplifier A71 is connected to the first potential reference terminal. A resistor R72 is connected between the output terminal and the inverting input terminal of the operational amplifier. The output terminal of the operational amplifier A71 serves as the first output terminal. The second input terminal 2 is directly connected to the first potential reference terminal; The third input terminal 3 is connected to the non-inverting input terminal of operational amplifier A72 via resistor R73. The non-inverting input terminal of operational amplifier A72 is also connected to the first potential reference terminal via resistor R75. Resistor R76 is connected between the output terminal and the inverting input terminal of operational amplifier A72. The inverting input terminal of operational amplifier A72 is connected to the first potential reference terminal via resistor R74. The resistance values ​​of resistors R73 and R74 are equal, and the resistance values ​​of resistors R75 and R76 are equal. The output terminal of operational amplifier A72 serves as the second output terminal.

[0045] In a preferred embodiment, the transmitter circuit includes two identical transmitter branches: The first input terminal to the third input terminal of the first transmission branch are respectively connected to the current sampling output terminal, the first potential reference terminal and the voltage sampling output terminal of the filament power supply 4, and are used to convert the filament current signal and the filament voltage signal into the corresponding signals required by the sampling unit. The first to third input terminals of the second transmission branch are respectively connected to the current sampling output terminal, the first potential reference terminal, and the voltage sampling output terminal of the bombardment power supply 5, and are used to convert the bombardment current signal and the bombardment voltage signal into the corresponding signals required by the sampling unit.

[0046] In this embodiment, the second transmitter branch includes: The first input terminal 4 is connected to the inverting input terminal of the operational amplifier A73 via resistor R77. The non-inverting input terminal of the operational amplifier A73 is connected to the first potential reference terminal. A resistor R78 is connected between the output terminal and the inverting input terminal of the operational amplifier. The output terminal of the operational amplifier A73 serves as the first output terminal. The second input terminal 5 is directly connected to the first potential reference terminal; The third input terminal 6 is connected to the non-inverting input terminal of operational amplifier A74 via resistor R79. The non-inverting input terminal of operational amplifier A74 is also connected to the first potential reference terminal via resistor R711. Resistor R712 is connected between the output terminal and the inverting input terminal of operational amplifier A74. The inverting input terminal of operational amplifier A74 is connected to the first potential reference terminal via resistor R710. The resistance values ​​of resistors R79 and R710 are equal, and the resistance values ​​of resistors R711 and R712 are equal. The output terminal of operational amplifier A74 serves as the second output terminal.

[0047] In this embodiment, each operational amplifier is powered by a ±5V regulated power supply, and the operational logic is as follows: Operational amplifier A71: , Transmit current to the filament; Operational amplifier A72: R73=R74, R75=R76, , Transmit voltage for the filament; Operational amplifier A73: , To bombard the transmitter current; Operational amplifier A74: R79=R710, R711=R712, , To bombard the transmitted voltage.

[0048] In an alternative implementation, the sampling unit 8 consists of an A / D converter A81, a digital processor A82, and a serial interface A83, with the circuit structure referring to... Figure 11 The digital processor A82 controls the A / D converter A81 to convert the analog signals if, vf, ib, and vb into digital signals respectively. , , and Then the digital signal , , and The signal is transmitted to the adjustment unit 10 via the serial interface A83 and the optical fiber 9. The optical fiber 9 is used to complete the signal transmission and high voltage insulation functions. The +5 power supply provides power to the A / D converter A81 and the digital processor A82, and the +V power supply provides power to the serial interface A83.

[0049] In one alternative implementation, the circuit structure of the adjustment unit 10 is as follows: Figure 12 As shown; including: The digital processor A92 is configured to determine adjustment parameters based on the sampled signal according to the interthermal electron gun single transformer cathode power supply control method as described in any of the preceding claims; The digital processor A92 is connected to the sampling unit 8 via serial interface A91, and to the host computer 11 via serial interface A93. It is connected to the DC voltage and current sampling output terminals of the power supply in the converter 2 via A / D converter A94 and isolation transmitter A95 in sequence. The adjustment parameters are converted into drive signals and input to the converter 2 via driver A96.

[0050] Preferably, the isolation transmitter A95 includes at least one isolation transmission branch, which includes a linear isolator A951 and an operational amplifier A953, with the specific structure as follows: Figure 13 As shown; The positive input terminal of the linear isolator A951 serves as the input terminal of the isolation transmitter branch. The negative input terminal of the linear isolator A951 is connected to a second potential reference terminal. The positive output terminal of the linear isolator A951 is connected to the non-inverting input terminal of the operational amplifier A953 via resistor R91. The non-inverting input terminal of the operational amplifier A953 is also connected to a third potential reference terminal via resistor R93. The negative output terminal of the linear isolator A951 is connected to the inverting input terminal of the operational amplifier A953 via resistor R92. A resistor R94 is connected between the output terminal and the inverting input terminal of the operational amplifier A953. The resistance values ​​of resistors R91 and R92 are equal, and the resistance values ​​of resistors R93 and R94 are equal. The output terminal of the operational amplifier A953 serves as the output terminal of the isolation transmitter branch. Preferably, the isolation transmitter A95 circuit includes two isolation transmission branches. The input terminal of the first isolation transmission branch is connected to the voltage sampling output terminal of the DC power supply of the converter, and the input terminal of the second isolation transmission branch is connected to the current sampling output terminal of the DC power supply of the converter 2. This is used to convert the DC power supply voltage signal and current signal into the corresponding signals required by the A / D converter 94. In this embodiment, the second isolation transmission branch includes: Linear isolator A952 and operational amplifier A954; The positive input terminal of the linear isolator A952 serves as the input terminal of the second isolation transmission branch. The negative input terminal of the linear isolator A952 is connected to the second potential reference terminal. The positive output terminal of the linear isolator A952 is connected to the non-inverting input terminal of the operational amplifier A954 via resistor R95. The non-inverting input terminal of the operational amplifier A954 is also connected to the third potential reference terminal via resistor R97. The negative output terminal of the linear isolator A952 is connected to the inverting input terminal of the operational amplifier A953 via resistor R96. A resistor R98 is connected between the output terminal and the inverting input terminal of the operational amplifier A953. The resistance values ​​of resistors R95 and R96 are equal, and the resistance values ​​of resistors R97 and R98 are equal. The output terminal of the operational amplifier A954 serves as the output terminal of the second isolation transmission branch. The input signal of the first isolation transmitter branch is The output signal is vd; the input signal of the second isolation transmitter branch is The output signal is id; then , β and γ are the conduction coefficients of linear isolators A951 and A952, respectively.

[0051] The analog signals vd and id are sent to the A / D converter A94, which converts the analog signals vd and id into digital signals respectively. and The A92 digital processor receives digital signals. , , , , and Simultaneously, it receives instructions from the host computer 11 to complete... Figure 1 , Figure 2 The control function outputs the adjustment parameter f in the form of drive signals g1 and g2, such as Figure 14 As shown, the driving signals g1 and g2 have the same frequency and are 180° out of phase, where τ is the inverter dead time and T is the inverter period. Meanwhile, the digital processor A92 monitors in real time. , , , , , The numerical relationship is used to determine the working status of the cathode. If a fault occurs, the drive signals g1 and g2 will be shut down and fed back to the host computer 11.

[0052] Drive signals g1 and g2 are isolated and amplified by driver A96 to output drive voltage. and drive respectively Figure 5 The power transistors V21 and V22 are in a push-pull working state. By changing the frequency of the drive signals g1 and g2, the operating frequency of the LLC inverter circuit of the converter 2 is changed, thereby adjusting the amplitude of the output voltage AC2 of the converter 2 and completing the power closed-loop control of the power supply.

[0053] Preferably, the driver A96 includes two isolated amplification branches A961 and A962, with the specific structure as follows: Figure 15 The input signal of the first isolation amplifier branch A961 is g1, and the output signal is g1. The input signal of the first isolation amplifier branch A962 is g2, and the output signal is g2. .

[0054] In this embodiment, the adjustment unit 10 requires an external positive power supply of V1, V2, and V3, wherein the common terminal of the positive power supplies V1 and V2 serves as the third potential reference terminal (O terminal). Figure 12 , Figure 13 and Figure 15 The negative terminal of the V3 positive power supply is connected to the second potential reference terminal (N terminal). In this embodiment, the negative terminal of the DC input of the converter 2 is used as the second potential reference terminal (N terminal). See Figure 12 and Figure 13 V1 positive power supply Figure 12 The digital processor A92 and A / D converter A94 are powered by V1 positive power supply. Figure 13 The operational amplifiers A952 and A954, and the linear isolators A951 and A952 are powered on their output sides, with V2 positive power supply... Figure 12 The serial interfaces A91 and A92 in the middle and Figure 15 The input side power supply of the isolation amplifier branches A961 and A962 is provided by V3 positive power supply. Figure 13 The linear isolators A951 and A952 are powered on the input side.

[0055] Any content or technical means not mentioned in the embodiments of this invention can be obtained by referring to the prior art. This disclosure does not limit the scope of the invention and therefore will not be elaborated further.

[0056] The embodiments of the present invention have been described in detail above, and the principles and implementation methods of the present invention have been explained. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of the present invention. Those skilled in the art should understand that the embodiments of the present invention can be provided as methods, computer software program products, or electronic devices, etc. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0057] It should be noted that the word "comprising" does not exclude the presence of components or steps not listed in the claims. The words "a" or "an" preceding a component do not exclude the presence of a plurality of such components. This invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer.

[0058] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0059] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for controlling the cathode power supply of a single transformer in an indirect-heated electron gun, characterized in that, The following multi-stage adjustment process is used to output adjustment parameters, which are the inverter frequency of the LLC inverter in the converter, and are used to change the excitation state of the primary side of the single transformer by adjusting the output of the converter. The multi-stage adjustment process includes: In the first stage, based on the incremental DC current output adjustment parameter, when the filament current rises and reaches the first preset threshold, the first adjustment parameter is recorded and the process switches to the second stage. In the second stage, the ramp function is given by the filament current feedback value at the end of the first stage, the filament current is used as feedback, and the first adjustment parameter is used as bias. When the bombardment current reaches the second preset threshold, the second adjustment parameter is recorded and the process switches to the third stage. In the third stage, the slope function value that decreases from the second adjustment parameter is used as the adjustment parameter. When the bombardment power reaches the given value, the third adjustment parameter is recorded and the process switches to the fourth stage. In the fourth stage, with the preset power setpoint as the target and the third adjustment parameter as the bias, the bombardment power is adjusted in a closed-loop feedback manner to maintain the bombardment power stable until the end of the operation.

2. The method for controlling the cathode power supply of an interthermal electron gun with a single transformer as described in claim 1, characterized in that, The incremental DC current output adjustment parameter includes: Using the ramp function of the power supply DC current as a given, the digital sampling signal of the power supply DC current as feedback, and the upper limit of the adjustment parameter as a bias, the first PID controller is started to output the adjustment parameter.

3. The method for controlling the single-transformer cathode power supply of an interthermal electron gun as described in claim 1, characterized in that, The first preset threshold is the preset minimum value of filament current.

4. The method for controlling the single-transformer cathode power supply of an interthermal electron gun as described in claim 1, characterized in that, The second preset threshold is the preset minimum bombardment current.

5. A single-transformer cathode power supply control circuit for an interthermal electron gun, characterized in that, include: Power supply; The converter has its input terminal connected to the power supply. The transformer has its primary side connected to the output terminal of the converter, and its secondary side connected to the filament power supply and the bombardment power supply, respectively. The positive and negative output terminals of the filament power supply are connected to the positive and negative poles of the filament, respectively. The positive output terminal of the bombardment power supply is connected to the cathode of the electron gun, and the negative output terminal is connected to the negative output terminal of the filament power supply as the first potential reference terminal, so as to form a bombardment voltage between the filament and the cathode. The sampling unit is connected to the output sampling terminal of the filament power supply and the output sampling terminal of the bombardment power supply through a transmitter, respectively, to synchronously collect filament voltage, filament current, bombardment voltage and bombardment current, convert them into digital signals and output them to the adjustment unit. The regulating unit is used to receive sampling signals, execute the interthermal electron gun single transformer cathode power supply control method as described in any one of claims 1-4, determine regulating parameters, and output control signals to the converter according to the regulating parameters to regulate the output voltage of the transformer.

6. The interthermal electron gun single-transformer cathode power supply control circuit as described in claim 5, characterized in that, The converter is a half-wave LLC inverter circuit structure, including a DC input terminal; wherein, Capacitors C21 and C22 are connected in series between the positive and negative terminals of the DC input terminal; and switching transistors V21 and V22 are connected in series between the positive and negative terminals of the DC input terminal. The control terminal of switching transistor V21 is connected to a first drive signal, and the control terminal of switching transistor V22 is connected to a second drive signal. The common node of the switching transistors V21 and V22 is connected to the common node of the capacitors C21 and C22 via inductor L21 and capacitor C23, thus forming the output terminal of the converter. The converter also includes a voltage divider sampling network and a current sampling resistor for acquiring the DC voltage and current supplied.

7. The interthermal electron gun single-transformer cathode power supply control circuit as described in claim 5, characterized in that, The transmitter includes at least one transmission branch, and the transmission branch includes: The first input terminal is connected to the inverting input terminal of operational amplifier A71 via resistor R71. The non-inverting input terminal of operational amplifier A71 is connected to the first potential reference terminal. Resistor R72 is connected between the output terminal and the inverting input terminal of the operational amplifier. The output terminal of operational amplifier A71 serves as the first output terminal. The second input terminal is directly connected to the first potential reference terminal; The third input terminal is connected to the non-inverting input terminal of operational amplifier A72 via resistor R73. The non-inverting input terminal of operational amplifier A72 is also connected to the first potential reference terminal via resistor R75. Resistor R76 is connected between the output terminal and the inverting input terminal of operational amplifier A72. The inverting input terminal of operational amplifier A72 is connected to the first potential reference terminal via resistor R74. The resistance values ​​of resistors R73 and R74 are equal, and the resistance values ​​of resistors R75 and R76 are equal. The output terminal of operational amplifier A72 serves as the second output terminal.

8. The interthermal electron gun single-transformer cathode power supply control circuit as described in claim 5, characterized in that, The secondary side of the transformer is also connected to an auxiliary power supply, which is used to convert AC power into ±5V and +V DC power to power the transmitter and each active functional device in the sampling unit.

9. The interthermal electron gun single-transformer cathode power supply control circuit as described in claim 5, characterized in that, The sampling unit includes: The digital processor 82A is connected to the transmitter via an A / D converter A81 and to the regulating unit via a serial interface A83. The digital processor 82A controls the A / D converter A81 to acquire digital signals of filament voltage, filament current, bombardment voltage, and bombardment current, and enables data exchange with the digital processor A92 of the adjustment unit.

10. The interthermal electron gun single-transformer cathode power supply control circuit as described in claim 5, characterized in that, The adjustment unit includes: The digital processor A92 is configured to determine adjustment parameters based on the sampled signal according to the interthermal electron gun single transformer cathode power supply control method according to any one of claims 1-4; The digital processor A92 is connected to the sampling unit via serial interface A91, to the host computer via serial interface A93, and sequentially connected to the DC voltage and current sampling output terminals of the power supply in the converter via A / D converter A94 and isolation transmitter A95; and the adjustment parameters are converted into drive signals and input to the converter via driver A96.

Images