Filament closed loop control device and control method

Abstract

The invention relates to the technical field of filament closed loop control devices, and particularly discloses a filament closed loop control device and a filament closed loop control method, the filament closed loop control device comprises an operation panel and a machine body rear shell connected with the rear side of the operation panel, the left side of the machine body rear shell is provided with a power interface, and the right side of the machine body rear shell is provided with a wiring port. According to the control device and the control method of the filament closed loop, through a dynamic maximum value taking strategy, a system automatically and preferentially adopts a filament current inner ring with faster response during starting or large-range adjustment, and automatically switches to a beam current outer ring with higher precision when a target value is approached, so that the unification of rapidness and stability is realized; and meanwhile, a set of fixed PID parameters can adapt to the ray tube and wide-range tube voltage change of the filament closed loop control device and control method with different characteristics, so that the equipment debugging process is remarkably simplified, the equipment universality is improved, and a better use effect is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of filament closed loop control device, in particular to a kind of filament closed loop control device and control method. BACKGROUND

[0002] In the field of industrial nondestructive testing, medical imaging and industrial CT (computed tomography), filament closed loop control device and control method play an irreplaceable role in X-ray technology. Its core principle is that the filament closed loop control device and control method generates high-energy electron beam through the filament closed loop control device and control method X-ray source, bombards the target material to generate X-ray, and the X-ray penetrates the detected object and is received by the detector to form an image that can be used for analysis. In this process, the stability and accuracy of the electron beam directly determine the quality of the imaging and the reliability of the detection results. Electron beam, also known as tube current or beam current, is the source of the filament of the electron gun in the filament closed loop control device and control method X-ray device. The filament emits electrons after being heated, so accurate control of the filament current is crucial to stabilize the beam, and the control device is the core component of stabilizing the beam, such as; US4775992A provides a cellular radio system comprising a plurality of cells which are grouped into clusters. Each cluster is assigned a cluster identifier. A mobile unit is assigned a particular paging time slot for receiving paging messages on a control channel. When there is a call to a mobile unit, the system broadcasts a paging message during the particular paging time slot assigned to the mobile unit in all cells within the cluster to which the mobile unit belongs. The mobile unit enters a sleep mode at times other than its assigned paging time slot to save power; CN108834294A provides a filament current closed loop sampling circuit and an X-ray high frequency high voltage generator. The filament current closed loop sampling circuit is arranged between the load circuit and the filament current closed loop circuit, and includes a current detection circuit, an input filter circuit, an effective value conversion circuit and a voltage following output circuit connected in sequence. The filament current closed loop sampling circuit is used to sample the alternating current signal flowing through the load circuit, and convert the alternating current signal into a set power direct current voltage signal and output to the filament current closed loop circuit to complete the closed loop feedback control of the filament current. The present application improves the sampling accuracy of the alternating current filament current by setting the filament current closed loop sampling circuit, indirectly improves the closed loop gain control accuracy, tube current accuracy and imaging clarity; Authorized publication number CN201854495U discloses a current control device for an X-ray tube. This device uses an analog selection switch to select either the filament current sampling unit or the tube current sampling unit, feeding the results back to the gain control unit. This forms two closed-loop gain control loops, which are then time-divisionally controlled to adjust the gain of both the filament current and the tube current. This multi-loop time-division control of the X-ray tube current allows for rapid increases in filament current to near the exposure current required, while also providing a more accurate tube current after normal operation. This makes the X-ray tube practical, convenient, and highly stable.

[0003] However, existing control devices are prone to system oscillation when rapidly adjusting the filament current to obtain a precise beam current, causing the beam current value to fluctuate at a low frequency near the target value and failing to stabilize quickly. At the same time, for "non-high-quality X-ray tubes" where the filament current and tube current have a nonlinear relationship, the traditional single closed-loop control strategy is difficult to achieve a precise and stable beam current output, making debugging difficult. Therefore, in order to address the above problems, it is urgent to innovate the design based on the existing control device. Summary of the Invention

[0004] The purpose of this invention is to provide a control device and method for a closed-loop filament circuit, in order to solve the problems mentioned in the background art. Current control devices are prone to system oscillation when rapidly adjusting the filament current to obtain a precise beam current, resulting in low-frequency fluctuations in the beam current value near the target value, making it impossible to stabilize quickly. At the same time, for "non-high-quality X-ray tubes" where the filament current and tube current have a nonlinear relationship, the traditional single closed-loop control strategy is difficult to achieve accurate and stable beam current output, and debugging is difficult.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a control device and control method for a filament closed-loop circuit, comprising: an operation panel, and a rear housing connected to the rear side of the operation panel, wherein a power interface is provided on the left side of the rear housing and a wiring port is provided on the right side of the rear housing; Also includes: The display panel is installed inside the operation panel, and the lower end of the display panel is equipped with operation buttons. The rear shell of the machine body is equipped with a mounting bracket, and the middle of the mounting bracket is equipped with an operational amplifier chip U3. The lower side of the operational amplifier chip U3 is equipped with a high-voltage isolation optocoupler U1, and the upper end of the operational amplifier chip U3 is equipped with a capacitor and resistor module. The carrying power supply pin is installed in the middle of the body rear shell, and the inner side of the carrying power supply pin is provided with a digital signal processor, the lower side of the carrying power supply pin is provided with a PWM drive chip U8, and the rear side of the PWM drive chip U8 is provided with a first output pin, the upper side of the carrying power supply pin is provided with a storage power supply module, and the rear side of the storage power supply module is provided with a second output pin, and the left side of the PWM drive chip U8 is connected with a power MOSFET tube Q1.

[0006] In a possible implementation, the high-voltage isolation optocoupler U1 electrically isolates the signal input from the wiring port, processes the beam current sampling signal and the tube voltage signal from the high-voltage side, and is isolated from the low-voltage control side, thereby preventing the risk of instantaneous high voltage from the high-voltage side from entering the low-voltage control part and burning the core chip.

[0007] In a possible implementation, the operational amplifier chip U3 performs signal processing work such as filtering, amplifying / attenuating, or biasing on the isolated signal, aims to provide a clean and stable signal source, and lays a hardware foundation for achieving a high-steady-state accuracy of ±0.5% for the entire system.

[0008] In a possible implementation, the digital signal processor calculates the two-way deviation of the primary side sampling and the beam feedback value in the obtained data in real time, performs "maximum value" comparison, selects one-way deviation as the input of the PID according to the result, and thus adapts to linear ray tubes and nonlinear ray tubes.

[0009] In a possible implementation, the digital signal processor uses a single PID output, so that when the system starts or needs to be quickly adjusted, the filament current deviation is usually large, the system preferentially enters the filament current inner loop fast following mode to realize fast response, and when the beam current approaches the target value, the beam current deviation becomes the main problem, the system automatically switches to the beam current outer loop precise correction mode to ensure the final accuracy.

[0010] In a possible implementation, the storage power supply module modulates the pulse width by changing the reference voltage or the compensation terminal voltage, thereby controlling the output power of the filament driving circuit, and finally accurately adjusting the filament temperature and the beam current size.

[0011] In a possible implementation, the PWM drive chip U8 receives a weak PWM signal from the MCU, amplifies it to a voltage sufficient to quickly and reliably drive the power MOSFET, provides sufficient driving current and voltage, ensures that the power MOSFET can quickly and completely switch, reduces the time it spends in the linear region, thereby reducing switching loss and heat generation, and improves the efficiency and reliability of the entire power stage.

[0012] In a possible implementation, the control method comprises the following steps: Step one, real-time acquisition of filament current sampling signal (If_primary) and beam current sampling signal (I_beam) through external sensors, and electrical isolation of the acquired beam current sampling signal and tube voltage signal by high-voltage isolation optocoupler U1, and filtering, amplification / attenuation or biasing processing of the isolated signals by operational amplifier chip U3 in cooperation with a capacitor-resistor module to provide a clean and stable signal source; Step two, the digital signal processor calculates the initial filament current given value (If_given) according to the received target beam current value (I_target) and tube voltage (HV) by querying a preset mapping table; the system enters a 1 kHz timing interrupt loop to ensure that the control algorithm runs in real time with millisecond-level precision; Step three, in each interrupt, the digital signal processor synchronously reads multiple ADC channels to obtain the actual filament current (If_primary) and actual tube current (I_beam) at the current time; and calculates the inner loop deviation and the outer loop deviation, respectively; Step four, comparison of |Δ_If| and |Δ_Ibeam| by taking the maximum value; Step five, the selected deviation is sent to the digital PID controller, and a control quantity is output; the PWM drive chip U8 converts the PID output into the driving voltage required by the power MOSFET tube Q1, modulates the PWM pulse width, controls the output power of the filament driving circuit, and accurately adjusts the filament temperature and beam current; Step six, for a non-linear ray tube, when the system mainly relies on beam current outer loop adjustment and Δ_Ibeam continuously decreases, the digital signal processor starts a background learning process, fine-tunes the If_given value according to the current data point, and updates the three-dimensional lookup table to realize adaptive learning capability; Step seven, real-time display of system working status, collected data and control parameters through a display panel, facilitating monitoring and debugging by an operator.

[0013] Compared with the prior art, the filament closed loop control device and control method has at least the following beneficial effects: through the dynamic maximum value strategy, the system automatically preferentially adopts the filament current inner loop with faster response during startup or wide range adjustment, and automatically switches to the beam outer loop with higher precision when approaching the target value, thereby realizing the unification of rapidity and stability, and a fixed set of PID parameters can adapt to the filament closed loop control device and control method of the ray tube with different characteristics and wide range of tube voltage changes, thereby significantly simplifying the equipment debugging process, improving the universality of the equipment, and having better use effect, and the specific contents are as follows. 1. The information flow input through the wiring port is subjected to electrical isolation processing by the operational amplifier chip U3, the capacitance resistance module, and the high-voltage isolation optocoupler U1, the beam sampling signal and the tube voltage signal from the high-voltage side are isolated from the low-voltage control ground, the risk of instantaneous high voltage from the high-voltage side flowing into the low-voltage control part and burning the core chip is eliminated, and the isolated signals are subjected to signal processing such as filtering, amplification / attenuation, or biasing, so as to provide a clean and stable signal source and lay a hardware foundation for the whole system to realize a high-steady-state precision of ±0.5%; 2. The digital signal processor synchronously reads multiple ADC channels to obtain accurate If_primary and I_beam at the current time, at this time, two deviation amounts of inner loop deviation and outer loop deviation are calculated, and one of the deviations is selected as the input of the PID according to the result, so that the system automatically preferentially adopts the filament current inner loop with faster response during startup or wide range adjustment, and automatically switches to the beam outer loop with higher precision when approaching the target value, thereby realizing the unification of rapidity and stability; 3. The PWM drive chip U8 converts the control amount output by the PID into an analog voltage required by the power MOSFET tube Q1, so as to change the width of the PWM wave of the drive MOSFET, provide sufficient drive current and voltage, ensure that the power MOSFET can be quickly and completely switched, reduce the time in the linear region, thereby reducing the switching loss and heat, improving the efficiency and reliability of the whole power stage, and finally adjusting the filament heating power. BRIEF DESCRIPTION OF DRAWINGS

[0014] The drawings described herein are used to provide further understanding of the present application, constitute a part of the present application, the illustrative embodiments of the present application and the description thereof are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings: Figure 1 It is a front view of the overall structure of the present application; Figure 2 It is a rear view of the overall structure of the present application; Figure 3 It is a front view of the cross-sectional structure of the present application; Figure 4 For the function drive and output detailed flow chart of the application; Figure 5 For the signal conduction path flow chart of the application; Figure 6 For the core processing and control detailed flow chart of the application; Figure 7 For the control circuit diagram of the application.

[0015] In the figure: 1, operation panel; 2, machine body rear shell; 3, display panel; 4, operation button; 5, power interface; 6, wiring port; 7, mounting bracket; 8, operational amplifier chip U3; 9, high-voltage isolation optocoupler U1; 10, capacitor resistance module; 11, bearing power supply pin; 12, digital signal processor; 13, PWM drive chip U8; 14, first output pin; 15, storage power supply module; 16, second output pin; 17, power MOSFET tube Q1. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application, so that the realization process of how the application applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented. Obviously, the described embodiments are only some of the embodiments of the application, not all.

[0017] Please refer to Figures 1-7 The application provides the following technical solutions: A filament closed loop control device and control method, comprising: operation panel 1, machine body rear shell 2, display panel 3, operation button 4, power interface 5, wiring port 6, mounting bracket 7, operational amplifier chip U3 8, high-voltage isolation optocoupler U1 9, capacitor resistance module 10, bearing power supply pin 11, digital signal processor 12, PWM drive chip U8 13, first output pin 14, storage power supply module 15, second output pin 16 and power MOSFET tube Q1 17. Specifically as Figure 1 , Figure 3 and Figure 5As shown, before the device is used, by connecting the data connection line to the right side of the wiring port 6 respectively, and connecting the power line to the left side of the power interface 5, by pressing the operation button 4 arranged at the front end of the operation panel 1, the electronic devices arranged inside the operation panel 1 and the body rear shell 2 gradually start to work under the drive of the power interface 5 and the power line, at this time a precise low inductance sampling resistor is connected in series in the primary side loop of the filament transformer, the voltage across the resistor is sent into the inside of the device after amplification and filtering by the operational amplifier chip U38 arranged inside the mounting frame 7 in cooperation with the capacitor resistance module 10, and the beam analog signal from the high voltage generator is input into the inside of the high voltage isolation optocoupler U19 through the wiring port 6 for electrical isolation, so that the isolated signal is matched to the ADC input range of the digital signal processor 12 after voltage lifting / attenuation, filtering, preventing the risk of instantaneous high voltage from the high voltage side from leaking into the low voltage control part and burning the core chip, at this time the device gradually loads parameters under the cooperation of the power interface 5 and the power line, so that the digital signal processor 12 calculates the initial filament current given value If_given according to the received I_target and HV by querying the preset mapping table under the influence of the power supply pin 11 bearing power supply and the storage power supply module 15. This provides a fast starting point for the system, at this time the device enters a 1kHz timing interrupt loop, ensuring that the control algorithm runs in real time with millisecond-level precision, and in each interruption, the digital signal processor 12 synchronously reads multiple ADC channels to obtain the accurate If_primary (actual filament current) and I_beam (actual tube current) at the current time, at this time two deviation amounts, the inner loop deviation and the outer loop deviation, are calculated respectively, and the absolute values of the actual filament current and the actual tube current are compared: at the beginning, the actual tube current I_beam is 0, and |Δ_Ibeam| is huge. At this time, the system will automatically select Δ_Ibeam as the PID input, and output the corresponding control instruction through the first output pin 14 and the second output pin 16 arranged on the back side, working in the beam outer loop mode to accelerate the heating and quickly approach the target. When the tube current approaches the target value, |Δ_Ibeam| becomes smaller. If the filament current If_primary suddenly changes due to power fluctuations, |Δ_If| may be greater than |Δ_Ibeam| at once. The system will immediately switch to Δ_If as the PID input, working in the filament current inner loop mode, to take advantage of the fast response of the inner loop to quickly suppress the interference and prevent it from affecting the stability of the tube current. This is "seamless dynamic switching", and the data stream information calculated by each component during the high-frequency operation of the device is displayed inside the display panel 3, so that the operator can judge the working state of the device by observing the displayed brief data; Specifically as Figure 2 , Figure 4 , Figure 6 and Figure 7As shown, in the device use area process, by sending the maximum deviation selected by calculation into the digital PID controller to calculate an output control quantity, so that the system automatically adopts the filament current inner ring with faster response when starting or large-scale adjustment, and automatically switches to the beam current outer ring with higher precision when approaching the target value, the unity of rapidity and stability is realized, and the PWM driving chip U813 converts the control quantity output by the PID into an analog voltage required by the power MOSFET tube Q117, so as to change the width of the PWM wave of the driving MOSFET, provide sufficient driving current and voltage, ensure that the power MOSFET can be quickly and completely switched, reduce the time in the linear region, thereby reducing the switching loss and heat, improving the efficiency and reliability of the entire power stage, and finally adjusting the filament heating power. In this process, for the non-linear tube, when the system mainly relies on the beam current outer ring for adjustment, and Δ_Ibeam is continuously reduced, it is considered that the system is converging, at this time, the DSP will start a slow background learning process, according to the current data point, fine-tune the value of If_given, so that it can more accurately generate the target I_target, and update the optimized corresponding relationship to the three-dimensional lookup table, so that the next time working under the same HV and I_target, the initial If_given given by the system will be more accurate, the adjustment time is further shortened, and the adaptive learning ability of more accurate use is realized.

[0018] The standard parts used in the application can be purchased from the market, and the special-shaped parts can be ordered according to the description and the drawings. The specific connection mode of each part adopts the conventional means such as bolts, rivets and welding in the prior art. The mechanical parts and equipment adopt conventional models in the prior art, and the circuit connection adopts the conventional connection mode in the prior art, which will not be described in detail here.

[0019] Although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art can modify the technical solutions described in the foregoing embodiments or make equivalent replacements to part of the technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A control device and control method for filament closed loop, comprising: The operation panel (1) and the operation panel (1) back side connecting body back shell (2), the left side of the body back shell (2) is provided with power interface (5), and the right side of the body back shell (2) is provided with wiring port (6); It is characterized by further comprising: The display panel (3) is installed in the operation panel (1), and the lower end of the display panel (3) is provided with an operation button (4), the inside of the body back shell (2) is provided with a mounting bracket (7), and the middle part of the mounting bracket (7) is provided with an operational amplifier chip U3 (8), the lower side of the operational amplifier chip U3 (8) is provided with a high-voltage isolation optical coupling U1 (9), and the upper end of the operational amplifier chip U3 (8) is provided with a capacitor resistance module (10); The bearing power supply pin (11) is installed in the middle part of the body back shell (2), and the inner side of the bearing power supply pin (11) is provided with a digital signal processor (12), the lower side of the bearing power supply pin (11) is provided with a PWM drive chip U8 (13), and the rear side of the PWM drive chip U8 (13) is provided with a first output pin (14), the upper side of the bearing power supply pin (11) is provided with a storage power supply module (15), and the rear side of the storage power supply module (15) is provided with a second output pin (16), and the left side of the PWM drive chip U8 (13) is connected with a power MOSFET tube Q1 (17).

2. The filament closed loop control apparatus and method of claim 1, wherein: The high-voltage isolation optical coupling U1 (9) electrically isolates the signal input from the wiring port (6), processes the beam sampling signal and tube voltage signal from the high-voltage side, and separates the high-voltage side from the low-voltage control side, so as to prevent the instantaneous high-voltage from the high-voltage side from entering the low-voltage control part and burning the core chip.

3. The filament closed loop control apparatus and method of claim 1, wherein: The operational amplifier chip U3 (8) performs signal processing work such as filtering, amplifying / attenuating or biasing on the isolated signal, aiming to provide a clean and stable signal source, and laying a hardware foundation for the whole system to realize a high-stability precision of ±0.5%.

4. The filament closed loop control apparatus and method of claim 1, wherein: The digital signal processor (12) calculates the two-way deviation of the original side sampling and the beam feedback value in the obtained data in real time, compares the maximum value, selects one-way deviation as the input of PID according to the result, and thus adapts to the linear ray tube and the nonlinear ray tube.

5. The filament closed loop control apparatus and method of claim 1, wherein: The digital signal processor (12) adopts single PID output, so that when the system starts or needs to be quickly adjusted, the filament current deviation is usually large, the system preferentially enters the filament current inner loop fast following mode to realize fast response, and when the beam approaches the target value, the beam deviation becomes the main problem, the system automatically switches to the beam outer loop precise correction mode to ensure the final precision.

6. The filament closed loop control apparatus and method of claim 1, wherein: The storage power supply module (15) modulates the pulse width by changing the reference voltage or compensation end voltage, so as to control the output power of the filament driving circuit, finally accurately adjust the filament temperature and beam size, and change the PWM control chip reference voltage or compensation end voltage to modulate the pulse width, so as to control the output power of the filament driving circuit, finally accurately adjust the filament temperature and beam size.

7. The filament closed loop control apparatus and method of claim 1, wherein: The PWM drive chip U8 (13) receives the weak electric PWM signal from the MCU, amplifies it to the voltage sufficient to quickly and reliably drive the power MOSFET, provides sufficient driving current and voltage, ensures that the power MOSFET can be quickly and completely switched, reduces the time in the linear region, thereby reduces the switching loss and heat, and improves the efficiency and reliability of the entire power stage.

8. The filament closed loop control apparatus and method of claim 1, wherein: The control method comprises the following steps: Step one, through the external sensor, real-time acquisition of filament current sampling signal (If_primary) and beam current sampling signal (I_beam), while the high-voltage isolation optocoupler U1 (9) carries out electrical isolation on the collected beam current sampling signal and tube voltage signal, and the isolated signal is filtered, amplified / attenuated or biased by the operational amplifier chip U3 (8) in cooperation with the capacitor-resistor module (10), to provide a clean and stable signal source; Step two, the digital signal processor (12) queries the preset mapping table according to the received target beam value (I_target) and tube voltage (HV), and calculates the initial filament current given value (If_given); the system enters a 1kHz timing interrupt loop, ensuring that the control algorithm runs in real time with millisecond-level precision; Step three, in each interrupt, the digital signal processor (12) synchronously reads multiple ADC channels to obtain the actual filament current (If_primary) and actual tube current (I_beam) at the current time; the inner loop deviation and the outer loop deviation are calculated respectively; Step four, the "max" comparison is performed on |Δ_If| and |Δ_Ibeam|; Step five, the selected deviation amount is sent to the digital PID controller, and the control amount is output; the PWM drive chip U8 (13) converts the PID output into the driving voltage required by the power MOSFET tube Q1 (17), modulates the PWM pulse width, controls the output power of the filament driving circuit, and accurately adjusts the filament temperature and beam size; Step six, for the non-linear ray tube, when the system mainly relies on the beam outer loop adjustment and Δ_Ibeam continuously decreases, the digital signal processor (12) starts the background learning process, fine-tunes the If_given value according to the current data point, and updates the three-dimensional lookup table, to realize the adaptive learning ability; Step seven, the system working state, collected data and control parameters are displayed in real time through the display panel (3), to facilitate the operator to monitor and debug.

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