High-voltage power supply control method of X-ray tube
By disassembling and modeling the circuit structure of the X-ray tube, a dynamic decoupling and adaptive sliding mode controller was designed, which solved the problem of stable output of the high-voltage power supply of the X-ray tube under various interferences, and realized the stability and adaptability of the system.
Patent Information
- Application Number
- CN202511372150.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-24
- Publication Date
- 2025-12-09
AI Technical Summary
In existing technologies, high-voltage power supplies for X-ray tubes are difficult to control stably under various interferences.
By disassembling the structure of the voltage circuit, filament circuit, and tube current circuit, a mechanism model is established, the coupling coefficient is calculated, and a dynamic decoupling controller and an adaptive sliding mode controller are designed. Simulation verification and physical verification are carried out, and the control parameters are optimized to achieve stable output.
Stable emission of high-power end-window type X-ray high-voltage power supply system and perfect adaptation with X-ray tube have been achieved, improving the system's stability and anti-interference capability.
Smart Images
Figure CN121091684A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power supply control technology, and in particular to a control method for a high-voltage power supply for an X-ray tube. Background Technology
[0002] X-ray high-voltage power supplies are widely used in various fields, including electrostatic dust removal in industry, mineral exploration equipment in mining, lasers in optics, and CT scanners in medicine, all of which require DC high-voltage power supplies.
[0003] High-power end-window X-ray tube high-voltage power supplies are mainly used in analytical high-power end-window X-ray tubes, which are the core components of X-ray fluorescence (XRF) instruments. They primarily consist of an ultra-thin beryllium window, cathode filament, anode target, high-vacuum ceramic tube, and a high-efficiency water-cooling mechanism. These power supplies provide a strong electric field of 60-80kV, causing the entire system to be accelerated and bombarded by a sufficient amount of thermionic electrons generated under this strong electric field. This generates a tube current of up to 150mA within a confined space, with a total power of up to 4kW. Only 1% of this energy is converted into X-ray photons that pass through the beryllium window; the remaining energy is concentrated as heat in an area of less than 10mm² on the target. Strong electric field, high beam current, high heat density, small size, and high stability are the most vivid descriptions and requirements for the operating conditions of high-power end-window analytical X-ray tube high-voltage power supplies.
[0004] In the control process of high-voltage power supply, there is coupling between tube voltage, filament circuit, filament current, etc. In addition, there are internal and external positional interferences in the system, which makes it difficult to achieve stable output control of high-voltage power supply. Summary of the Invention
[0005] This application provides a high-voltage power supply control method for X-ray tubes to solve the problem in the prior art that the high-voltage power supply of X-ray tubes is difficult to achieve stable output control under the influence of various interferences.
[0006] This application provides a high-voltage power supply control method for an X-ray tube, including: Disassembly was used to determine the structure of the voltage circuit, filament circuit, and tube current circuit; Establish a mechanism model based on the loop structure; The coupling coefficient is calculated based on the mechanism model, and an unknown interference model is established. Based on the matrix composed of coupling coefficients, a dynamic decoupling controller is designed, and an adaptive sliding mode controller is designed for the unknown disturbance model. Simulations were performed on the dynamic decoupling controller and the adaptive sliding mode controller to obtain the optimized control parameters. Physical verification was conducted using optimized control parameters to verify the actual adaptability of the optimized control parameters. The optimized control parameters, which have been verified by physical testing, are iteratively optimized to obtain the optimal control parameters; Optimal control parameters are used to control the high-voltage power supply of the X-ray tube.
[0007] In one possible implementation, after determining the structure of the voltage circuit, filament circuit, and tube current circuit, the coupling path is located, and the interference sources are classified. The coupling path includes forward coupling and reverse coupling, and the interference sources are classified into known interference and unknown interference.
[0008] In one possible implementation, the unknown disturbance is treated as a perturbation term, and the perturbation term is superimposed on the output of the mechanistic model to obtain the unknown disturbance model.
[0009] In one possible implementation, the coupling coefficient is calculated by experimental measurement or by derivation based on X-ray tube emission theory.
[0010] In one possible implementation, a dynamic decoupling controller is designed using the inverse system decoupling method.
[0011] In one possible implementation, simulation verification of the dynamic decoupling controller and the adaptive sliding mode controller is performed, including: Simulation model construction: Integrating the mechanism model, unknown disturbance model, dynamic decoupling controller, and adaptive sliding mode controller, a simulation model is obtained; Operating condition testing and performance evaluation: Input simulation parameters into the simulation model to obtain operating condition evaluation results; Parameter optimization: The adaptive sliding mode controller is adjusted based on the operating condition evaluation results until the optimization objective is met, thus obtaining the optimized control parameters.
[0012] In one possible implementation, when using theoretically optimized control parameters for physical verification, the verification includes no-load testing, load testing, interference testing, and long-term reliability testing.
[0013] The high-voltage power supply control method for an X-ray tube disclosed in this application has the following advantages: By disassembling, analyzing, and modeling various coupling and interference terms of the high-voltage power supply in the X-ray tube, the optimized control parameters were obtained to achieve stable emission of the high-power end-window X-ray high-voltage power supply system and perfect adaptation to the high-power end-window X-ray. Attached Figure Description
[0014] To more clearly illustrate the technical solutions in the embodiments of this application 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 some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0015] Figure 1 A flowchart illustrating a high-voltage power supply control method for an X-ray tube provided in this application embodiment. Detailed Implementation
[0016] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0017] Figure 1 A flowchart illustrating a high-voltage power supply control method for an X-ray tube provided in this application embodiment. This application embodiment provides a high-voltage power supply control method for an X-ray tube, including: S100, disassemble to determine the structure of voltage circuit, filament circuit and tube current circuit; S110, Establish a mechanism model based on loop structure; S120, calculate the coupling coefficient based on the mechanism model and establish an unknown interference model; S130, based on the matrix composed of coupling coefficients, designs a dynamic decoupling controller and an adaptive sliding mode controller for unknown disturbance models; S140, Simulation verification of dynamic decoupling controller and adaptive sliding mode controller is performed to obtain optimized control parameters; S150 uses optimized control parameters for physical verification to verify the actual adaptability of the optimized control parameters. S160, iteratively optimizes the optimized control parameters that have been verified by physical samples to obtain the optimal control parameters; S170 utilizes optimal control parameters to control the high-voltage power supply of the X-ray tube.
[0018] For example, the result of disassembling the circuit structure includes a voltage circuit, a filament circuit, and a current-carrying circuit, which are represented as follows.
[0019] The voltage circuit consists of the following components in sequence: three-phase power grid → AC-DC rectification → DC-DC high-voltage conversion → X-ray tube anode, with the tube voltage U_tube as the core component.
[0020] The filament circuit consists of the following components in sequence: low-voltage power supply → Buck converter → filament heating, with the filament current I_f as the core component.
[0021] The tube current loop consists of the following components: the movement of electrons between the anode and cathode inside the tube forms the tube current I_a, which is affected by both U_tube and I_f.
[0022] Furthermore, after determining the structure of the voltage circuit, filament circuit, and tube current circuit, the coupling path is located, and the interference sources are classified. The coupling path includes forward coupling and reverse coupling, and the interference sources are divided into known interference and unknown interference.
[0023] Specifically, positive coupling includes: increased I_f → increased electron emission from the filament → increased I_a; increased U_tube → enhanced electron acceleration force → increased I_a. Reverse coupling includes: increased I_a → voltage drop fluctuations in the tube → disturbances in U_tube → indirectly affecting the I_f control accuracy of the filament circuit.
[0024] Known interferences include: inherent coupling between tube current and voltage / filament circuit, and load impedance changes caused by X-ray tube target temperature fluctuations. Unknown interferences include: mains voltage fluctuations (e.g., ±10%), component parameter drift such as high-voltage capacitor aging / filament resistance temperature drift, and electromagnetic interference (EMI).
[0025] Furthermore, the mechanistic model includes models for the voltage loop and models for the filament loop. The voltage loop model will be explained below using a three-phase rectification-LC filter-phase-shifted full-bridge DC-DC converter as an example.
[0026] In the three-phase rectification-LC filtering stage, the grid line voltage U_line, after uncontrolled rectification, outputs an average DC voltage U_dc1 = 1.35 × U_line. After LC filtering, the dynamic model is: the rate of change of current in capacitor C (C × dU_dc2 / dt) = (U_dc1 - U_dc2) / R_eq - i_in, where U_dc2 is the filtered bus voltage, R_eq is the equivalent internal resistance of the rectifier bridge, and i_in is the DC-DC conversion input current.
[0027] In the phase-shifted full-bridge DC-DC converter stage, the output is controlled by adjusting the phase shift angle φ of the leading arm and the lagging arm. When switching losses are ignored, U_tube=U_dc2×(φ / π)×η, where η is the conversion efficiency, which is usually ≥0.92, and φ is the core control variable.
[0028] When modeling the filament circuit, the Buck converter will be used as an example below.
[0029] The filament is an inductive load. The dynamic equation of the inductor current i_L (i.e. I_f) of the Buck converter is: L×di_L / dt+R_f×i_L+U_C=U_dc2×D, where L is the inductance value, R_f is the filament resistance, U_C is the voltage of the filter capacitor, D is the duty cycle, and D is the core control variable.
[0030] The voltage change rate of the filter capacitor C_f is: (C_f×dU_C / dt)=i_L-U_C / R_load, where R_load is the equivalent load resistance of the filament, and at the rated temperature R_f≈R_load.
[0031] Ignoring the high-frequency influence of the capacitor, the transfer function can be simplified to: the transfer function between I_f and D is G_f(s)=U_dc2 / (L×s+R_f), which reflects the control sensitivity of D to I_f.
[0032] Furthermore, the coupling coefficients k_a-f and k_a-U can be expressed as: k_a-f=∂I_a / ∂I_f, k_a-U=∂I_a / ∂U_tube. The coupling coefficients can be calculated by experimental measurement or by derivation based on X-ray tube emission theory. When using experimental measurement, U_tube needs to be fixed, and the changes in I_a are recorded after changing I_f. The slope of the fitted curve is k_a-f.
[0033] The derivation of the coupling coefficient based on X-ray tube emission theory is as follows: I_a increases with increasing filament temperature T and U_tube, conforming to the Richardson-de Siemann law, i.e., I_a = A × S × T. 2 ×e^(-φ' / (kT))×(1-e^(-eU_tube / (kT)), where A is Richardson's constant, with a value of approximately 120A / (m²・K). 2 S is the filament emitting area, φ' is the filament work function, k is the Boltzmann constant, and e is the electron charge.
[0034] Furthermore, the unknown disturbance is treated as a perturbation term, and the perturbation term is superimposed on the output of the mechanism model to obtain the unknown disturbance model.
[0035] When establishing the unknown disturbance model, the unknown disturbances used are power grid fluctuations and parameter drift, etc. These unknown disturbances will be uniformly regarded as disturbance terms d(t). After superimposing them on the mechanism model, the unknown disturbance model of each loop can be expressed as: Voltage loop: U_tube(t)=G_U(s)×D_U(s)+d_U(t), where G_U(s) is the voltage loop transfer function, D_U(s) is the voltage control quantity, and d_U(t) is the voltage disturbance; Filament circuit: I_f(t)=G_f(s)×D_f(s)+d_f(t), where D_f(s) is the filament control quantity and d_f(t) is the filament current disturbance; Tube current loop: I_a(t)=k_a-f×I_f(t)+k_a-U×U_tube(t)+d_a(t), where d_a(t) is the tube current disturbance.
[0036] Furthermore, in this embodiment, the inverse system decoupling method is used to design a dynamic decoupling controller. The design process is as follows: Clearly define the control objectives: U_tube tracing command U_tube*, I_a tracing command I_a*; Derivation of filament current command: I_f*=(I_a*-k_a-U×U_tube*) / k_a-f, ensuring that I_a is controlled only by I_f*; Add a decoupling compensation term: In the filament circuit control, introduce ΔD_f=(k_a-U / k_a-f)×ΔD_U, where ΔD_U is the control deviation of U_tube, to offset the coupling effect of U_tube on I_a, making the two circuits approximately independent.
[0037] The design flow of the adaptive sliding mode controller is as follows: Sliding surface: Where e(t) is the tracking error, e(t) = U_tube* - U_tube, and λ>0 is the integral coefficient; Adaptive control law: Control quantity D_U(t) = D_U0(t) + ŵ_dU(t), where D_U0(t) is the nominal control quantity and ŵ_dU(t) is the disturbance estimate; Perturbation estimation update: The rate of change of ŵ_dU(t) = γ × s(t) × (∂U_tube / ∂D_U), where γ > 0 is the adaptive gain to ensure that ŵ_dU(t) converges to the true perturbation d_U(t), thereby canceling out the unknown disturbance.
[0038] Furthermore, simulation verification was performed on the dynamic decoupling controller and the adaptive sliding mode controller, including: Simulation model construction: Based on Matlab / Simulink, the simulation model is obtained by integrating the mechanism model, the unknown disturbance model, the dynamic decoupling controller and the adaptive sliding mode controller. Operating condition testing and performance evaluation: Input simulation parameters into the simulation model to obtain operating condition evaluation results; Parameter optimization: The adaptive sliding mode controller is adjusted based on the operating condition evaluation results until the optimization objective is met, thus obtaining the optimized control parameters.
[0039] Specifically, the operating condition assessment includes the following: Rated steady-state conditions: Evaluate the stability of U_tube (target ≤0.5%) and I_a (target ≤1%). Load mutation condition (I_a*±20%): Evaluate overshoot (target ≤5%) and settling time (target ≤10ms); Power grid fluctuation condition (U_line±10%): Assess the fluctuation amplitude of U_tube / I_a (target ≤2%). Component drift condition (R_f±5%): Evaluate tracking error (target ≤1%).
[0040] During parameter optimization, if the overshoot exceeds the limit, adjust the integral coefficient λ; if the anti-interference is insufficient, increase the adaptive gain γ, and iterate until the target is met.
[0041] Furthermore, when using theoretical optimization of control parameters for physical verification, the verification includes no-load testing, load testing, interference testing, and long-term reliability testing.
[0042] The optimized control parameters, which have been verified by physical testing, are iteratively optimized, including the following process: Model correction: If the temperature drift of the filament resistance causes the I_f deviation, add a temperature compensation term R_f(T)=R_f0×(1+αT) to the model, where R_f0 is the resistance at room temperature and α is the temperature coefficient of resistance, and re-derive the transfer function. Control strategy optimization: If EMI causes control chatter, add a boundary layer to the sliding mode control, that is, use linear control when s(t)∈[-δ,δ], where δ is the boundary layer thickness, to suppress chattering; Adaptability adjustment: If batch differences in X-ray tubes cause deviations in I_a, a batch calibration function is added to update the coupling coefficient matrix K based on the measured k_a-f. Final acceptance criteria: Stability: U_tube stability ≤ 0.5% and I_a stability ≤ 1% within 24 hours; Interference resistance: When the power grid fluctuates by ±10% or the load changes by ±30%, the adjustment time is ≤10ms and there is no overshoot; Compatibility: Compatible with 10-50kW end-window type X-ray tubes, batch-to-batch I_a deviation ≤1%; Reliability: Mean Time Between Failures (MTBF) ≥ 10,000 h.
[0043] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.
[0044] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.
Claims
1. A high-voltage power supply control method for an X-ray tube, characterized in that, include: Disassembly was used to determine the structure of the voltage circuit, filament circuit, and tube current circuit; Establish a mechanism model based on the loop structure; The coupling coefficient is calculated based on the aforementioned mechanism model, and an unknown interference model is established. Based on the matrix composed of the coupling coefficients, a dynamic decoupling controller is designed, and an adaptive sliding mode controller is designed for the unknown interference model. The dynamic decoupling controller and the adaptive sliding mode controller were simulated and verified to obtain optimized control parameters; The optimized control parameters were used for physical verification to verify their actual adaptability. The optimized control parameters, which have been verified by physical testing, are iteratively optimized to obtain the optimal control parameters; The high-voltage power supply of the X-ray tube is controlled using the aforementioned optimal control parameters.
2. The high-voltage power supply control method for an X-ray tube according to claim 1, characterized in that, After determining the structure of the voltage circuit, filament circuit, and tube current circuit, the coupling path is located, and the interference sources are classified. The coupling path includes forward coupling and reverse coupling, and the interference sources are divided into known interference and unknown interference.
3. The high-voltage power supply control method for an X-ray tube according to claim 2, characterized in that, The unknown interference is treated as a disturbance term, and the disturbance term is superimposed on the output of the mechanism model to obtain the unknown interference model.
4. The high-voltage power supply control method for an X-ray tube according to claim 1, characterized in that, The coupling coefficient is calculated by experimental measurement or by derivation based on X-ray tube emission theory.
5. The high-voltage power supply control method for an X-ray tube according to claim 1, characterized in that, The dynamic decoupling controller is designed using the inverse system decoupling method.
6. The high-voltage power supply control method for an X-ray tube according to claim 1, characterized in that, Simulation verification of the dynamic decoupling controller and the adaptive sliding mode controller includes: Build a simulation model: Integrate the mechanism model, the unknown disturbance model, the dynamic decoupling controller, and the adaptive sliding mode controller to obtain a simulation model; Operating condition testing and index evaluation: Input the simulation parameters into the simulation model to obtain the operating condition evaluation results; Parameter optimization: The adaptive sliding mode controller is adjusted according to the working condition evaluation results until the optimization target is met, and the optimized control parameters are obtained.
7. The high-voltage power supply control method for an X-ray tube according to claim 1, characterized in that, When using the aforementioned theory to optimize control parameters for physical verification, the verification includes no-load testing, load testing, interference testing, and long-term reliability testing.