An x-ray tube filament current control method

Abstract

The application is an X-ray tube filament current control method, and particularly relates to the technical field of X-ray tubes. The method comprises the following steps: according to N sample current sampling values and N sample current actual values, substituting the values into an N-order polynomial to perform a fitting operation, obtaining each coefficient of the N-order polynomial to construct a voltage mathematical model; obtaining a filament current sampling value; according to the voltage mathematical model of the X-ray tube filament, processing the filament current sampling value to obtain a filament current prediction value; and according to an error between the filament current prediction value and a target filament current value, adjusting a drive signal duty cycle of a half-bridge inverter circuit to adjust the filament current flowing through the X-ray tube. Based on the above scheme, the accuracy is high when the X-ray tube filament current control function is realized.

Description

Technical Field

[0001] This application relates to the field of X-ray tube technology, specifically to a method for controlling the filament current of an X-ray tube. Background Technology

[0002] X-ray inspection has important applications in hospital patient diagnosis, industrial non-destructive testing, and railway station security checks. As the core component of X-ray inspection, the performance parameters of the X-ray tube are subject to very strict requirements in practical applications.

[0003] An X-ray tube is a vacuum diode operating at high voltage. It contains two electrodes: an anode and a cathode. The cathode is a filament that emits electrons, and the anode is a target that receives the electron bombardment. When a sufficient current is applied to the filament to generate an electron cloud, and a sufficient voltage (in the kilovolt range) is applied between the anode and cathode, the electron cloud is drawn towards the anode. At this point, the electrons collide with the target at high energy and speed. Upon reaching the target surface, their motion is suddenly halted, and a small portion of their kinetic energy is converted into radiation energy, emitted as X-rays. Changing the filament current alters the filament temperature and the amount of electrons emitted, thereby changing the tube current and X-ray intensity. In existing technology, open-loop control is used to regulate the power supply to the X-ray tube filament, thus changing the tube current and X-ray intensity.

[0004] However, open-loop control lacks real-time feedback and has poor accuracy. Summary of the Invention

[0005] This application provides a method for controlling the filament current of an X-ray tube, which achieves high accuracy in controlling the filament current of the X-ray tube. The technical solution is as follows.

[0006] On the one hand, a method for controlling the filament current of an X-ray tube is provided, the method comprising:

[0007] Obtain N sample current values ​​and N sample current actual values; the sample current values ​​are obtained by sampling the current of the X-ray tube filament when the actual sample current flows through the X-ray tube filament under the bus voltage; N≥2 and N is a positive integer;

[0008] Based on the N sample current values ​​and the N sample current actual values, the Nth degree polynomial is substituted into the Nth degree polynomial for fitting operation to obtain the coefficients of each term of the Nth degree polynomial to construct a voltage mathematical model.

[0009] Obtain the filament current sampling value; the filament current sampling value is obtained by sampling the current of the X-ray tube filament under the bus voltage;

[0010] Based on the voltage mathematical model, the sampled filament current values ​​are processed to obtain the predicted filament current values;

[0011] Based on the error between the predicted filament current and the target filament current, the duty cycle of the drive signal of the half-bridge inverter circuit is adjusted to regulate the filament current flowing through the X-ray tube.

[0012] The Nth degree polynomial includes:

[0013] I out =a1+a2*(I in ) 1 +a3*(I in ) 2 +a4*(I in ) 3 +…+a N *(I in ) N-1

[0014] Among them, I out I is the actual value of the sample current. in The sampled current values ​​are a1, a2, ..., a N Let be the coefficients of each term in the Nth degree polynomial.

[0015] In another aspect, an X-ray tube filament current control device is provided, the device comprising:

[0016] The sample acquisition module is used to acquire N sample current sampling values ​​and N sample current actual values; the sample current sampling values ​​are the currents obtained by sampling the X-ray tube filament when the actual sample current flows through the X-ray tube filament under the bus voltage; N≥2 and N is a positive integer;

[0017] The fitting module is used to perform a fitting operation by substituting the N sample current values ​​and the N sample current actual values ​​into an Nth-degree polynomial to obtain the coefficients of each term of the Nth-degree polynomial in order to construct a voltage mathematical model.

[0018] The data acquisition module is used to acquire the filament current sampling value; the filament current sampling value is obtained by sampling the current of the X-ray tube filament under the bus voltage;

[0019] The current prediction module is used to process the sampled filament current value according to the voltage mathematical model to obtain the predicted filament current value.

[0020] The current regulation module is used to adjust the duty cycle of the drive signal of the half-bridge inverter circuit according to the error between the predicted value of the filament current and the target value of the filament current, so as to regulate the filament current flowing through the X-ray tube.

[0021] The Nth degree polynomial includes:

[0022] I out =a1+a2*(I in ) 1 +a3*(I in ) 2 +a4*(I in ) 3 +…+a N *(I in ) N-1

[0023] Among them, I out I is the actual value of the sample current. in The sampled current values ​​are a1, a2, ..., a N Let be the coefficients of each term in the Nth degree polynomial.

[0024] In one possible implementation, the voltage mathematical model includes an Nth-degree polynomial; the coefficients of the Nth-degree polynomial are obtained by fitting the sampled current values ​​with the actual sample current values.

[0025] The step of processing the sampled filament current value according to the voltage mathematical model to obtain the predicted filament current value includes:

[0026] The sampled filament current values ​​are processed according to the Nth degree polynomial to obtain the predicted filament current values.

[0027] In one possible implementation, processing the sampled filament current value according to the Nth-degree polynomial to obtain the predicted filament current value includes:

[0028] Among the Nth degree polynomials corresponding to multiple working ranges, the target Nth degree polynomial for the working range where the bus voltage is located is selected.

[0029] Based on the target Nth degree polynomial, the sampled filament current values ​​are processed to obtain the predicted filament current values.

[0030] In one possible implementation, the total operating range of the bus voltage can also be obtained;

[0031] The total operating range of the bus voltage is divided into M equal parts according to each voltage endpoint, and the operating range of any one bus voltage is selected.

[0032] Within the operating range of the bus voltage, when N sample current actual values ​​flow through the X-ray tube filament, the current of the X-ray tube filament is sampled to obtain N sample current sampling values.

[0033] In one possible implementation, among the Nth-degree polynomials corresponding to multiple operating ranges, a target Nth-degree polynomial for the operating range where the bus voltage is located is selected, including:

[0034] When the voltage difference between the bus voltage and the target voltage endpoint among the plurality of voltage endpoints is less than or equal to the voltage threshold, the Nth degree polynomial corresponding to the target voltage endpoint is determined as the target Nth degree polynomial in the operating range of the bus voltage.

[0035] In one possible implementation, among the Nth-degree polynomials corresponding to multiple operating ranges, a target Nth-degree polynomial for the operating range where the bus voltage is located is selected, including:

[0036] When the voltage difference between the bus voltage and any of the plurality of voltage endpoints is greater than the voltage threshold, the two voltage endpoints closest to the bus voltage are selected as candidate voltage endpoints.

[0037] The Nth degree polynomials of the two candidate voltage endpoints are determined as the target Nth degree polynomial.

[0038] In one possible implementation, the sampled filament current value is processed according to the Nth-degree polynomial to obtain a predicted filament current value, including:

[0039] The filament current sample value is processed using an Nth-degree polynomial from the two candidate voltage endpoints and the following formula to obtain the predicted filament current value:

[0040] I i =a i1 +a i2 *I in +a i3 *I in *I in +a i4 *I in *I in *I in ;

[0041] I i+1 =a (i+1)1 +a (i+1)2 *I in +a (i+1)3 *I in *I in +a (i+1)4 *I in *I in *I in ;

[0042] I out =(V in -V i )*(Ii+1 -I i ) / (V i+1 -V i )+I i ;

[0043] Among them, I i Let a be the predicted value of the filament current at the i-th voltage endpoint. i1 a i2 a i3 and a i4 For I i The corresponding coefficients of the Nth degree polynomial, V i For I i The corresponding bus voltage value, I i+1 Let a be the predicted value of the filament current at the (i+1)th voltage endpoint. (i+1)1 a (i+1)2 a (i+1)3 and a (i+1)4 For I i+1 The corresponding coefficients of the Nth degree polynomial, V i+1 For I i+1 The corresponding bus voltage value, I in I is the current filament current sampling value. out V is the predicted value of the current filament current. in This is the current bus voltage value.

[0044] In another aspect, a computer device is provided, the computer device including a processor and a memory, the memory storing at least one instruction, the at least one instruction being loaded and executed by the processor to implement the above-described X-ray tube filament current control method.

[0045] In another aspect, a computer-readable storage medium is provided, wherein at least one instruction is stored therein, the at least one instruction being loaded and executed by a processor to implement the above-described X-ray tube filament current control method.

[0046] In another aspect, a computer program product or computer program is provided, the computer program product or computer program including computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, causing the computer device to perform the above-described X-ray tube filament current control method.

[0047] The technical solution provided in this application may include the following beneficial effects:

[0048] In this application, an Nth-degree polynomial can be fitted using sampled current values ​​and actual sampled current values ​​to obtain the coefficients of the Nth-degree polynomial and construct a voltage mathematical model. This voltage mathematical model then represents the mapping relationship between the sampled filament current values ​​and the actual values. Therefore, in actual operation, sampled filament current values ​​can be obtained first; then, based on the voltage mathematical model of the X-ray tube filament, the sampled filament current values ​​are processed to obtain predicted filament current values; finally, based on the error between the predicted filament current value and the target filament current value, the duty cycle of the drive signal of the half-bridge inverter circuit is adjusted to regulate the filament current flowing through the X-ray tube. Therefore, after obtaining the predicted filament current value that reflects the actual filament current on the X-ray tube filament, the above scheme can readjust the duty cycle of the drive signal of the half-bridge inverter circuit and re-obtain the sampled filament current value based on this predicted filament current value until the error between the predicted filament current value and the target filament current value reaches the required level, forming a closed-loop regulation and improving the accuracy of X-ray tube filament current control. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0050] Figure 1 This is a schematic diagram of the structure of an X-ray tube filament current control system according to an exemplary embodiment.

[0051] Figure 2 This is a flowchart illustrating an X-ray tube filament current control method according to an exemplary embodiment.

[0052] Figure 3 This is a flowchart illustrating an X-ray tube filament current control method according to an exemplary embodiment.

[0053] Figure 4 A flowchart illustrating an example of an X-ray tube filament current control method according to an embodiment of this application is shown.

[0054] Figure 5 This is a structural block diagram of an X-ray tube filament current control device according to an exemplary embodiment.

[0055] Figure 6 This is a structural block diagram of a computer device according to an exemplary embodiment. Detailed Implementation

[0056] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. 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.

[0057] In the description of the embodiments of this application, the term "correspondence" may indicate that there is a direct or indirect correspondence between two things, or that there is an association between two things, or that there is a relationship of instruction and being instructed, configuration and being configured, etc.

[0058] In the embodiments of this application, "predefined" can be achieved by pre-storing corresponding codes, tables or other means that can be used to indicate relevant information in the device (e.g., including terminal devices and network devices). This application does not limit the specific implementation method.

[0059] Figure 1 This is a schematic diagram illustrating the structure of an X-ray tube filament current control system according to an exemplary embodiment. The X-ray tube filament current control system includes a bus voltage source, an inverter module, a filament transformer, a filament current acquisition module, an X-ray tube, a CPU, a drive module, and a bus voltage sampling module.

[0060] This inverter module can convert the bus voltage provided by the bus voltage source ( Figure 1 V in the middle dc The DC voltage signal is inverted into an AC voltage signal. Since there is a high voltage across the X-ray tube, the X-ray tube can be isolated from the CPU control circuit through a filament transformer. The AC voltage signal (as the AC voltage signal on the primary side of the filament transformer) is then converted into a secondary AC voltage signal through the gate ratio via the filament transformer, so as to act on the X-ray tube.

[0061] The filament current acquisition module can collect the primary current of the filament transformer and process it to obtain a DC signal of the filament current. The CPU can calculate the effective value of the DC signal of the filament current, and dynamically adjust the duty cycle of the PWM (Pulse Width Modulation) based on the difference between the effective value of the DC signal of the filament current and the preset target current value, and send a drive signal to the drive module. The drive module processes the drive signal into a control signal for the inverter module to control the inverter module to adjust the duty cycle during the inverter process.

[0062] Optionally, the filament current acquisition module includes a current transformer and a rectifier module. The current transformer is used to isolate the AC voltage signal from the CPU control circuit and to acquire the primary current of the filament transformer, converting it into a secondary AC current signal through the gate ratio. The rectifier module can rectify the secondary AC current signal, for example, by performing half-wave rectification or full-wave rectification, to obtain the DC signal of the filament current.

[0063] Optionally, the filament current calculation module in the CPU calculates the effective value of the filament current DC signal.

[0064] Optionally, a preset target current value can be set via a filament current setting module. This filament current setting module can be implemented using host computer software.

[0065] Since the AC signal changes when the bus voltage changes, a bus voltage sampling module is set up to sample the bus voltage and transmit the sampling results to the CPU. The CPU can adjust the duty cycle of the AC signal based on the change in bus voltage, combined with the effective value of the filament current DC signal and the difference between the preset target current value.

[0066] Figure 2 This is a flowchart illustrating a method for controlling the filament current of an X-ray tube according to an exemplary embodiment. This method can be applied to, for example... Figure 1 In the aforementioned X-ray tube filament current control system, such as Figure 2 As shown, the X-ray tube filament current control method may include the following steps:

[0067] Step 201: Obtain N sample current values ​​and N sample current actual values.

[0068] The sample current is the current obtained by sampling the X-ray tube filament when the actual sample current flows through the X-ray tube filament under the bus voltage.

[0069] The actual value of the sample current is the current value that actually flows through the filament of the X-ray tube, which can be measured using current measuring equipment, such as an oscilloscope.

[0070] The sampled current values ​​correspond to the bus voltage.

[0071] Step 202: Based on the N sample current values ​​and the N sample current actual values, substitute them into the Nth degree polynomial to perform a fitting operation, and obtain the coefficients of each term of the Nth degree polynomial to construct a voltage mathematical model.

[0072] The voltage mathematical model was trained using an existing sample dataset. This dataset contains N sample current values ​​and N sample actual current values. The purpose of training the voltage mathematical model is to ensure that the predicted filament current value obtained by the model based on the sampled filament current values ​​is as close as possible to the actual filament current value on the X-ray tube filament.

[0073] By using the sampled current values ​​as the independent variable of an Nth-degree polynomial and the actual sampled current values ​​as the dependent variable, and by substituting the N sampled current values ​​and the N actual sampled current values ​​into the Nth-degree polynomial, the coefficients of the Nth-degree polynomial can be solved, thereby completing the training of the voltage mathematical model.

[0074] The Nth degree polynomial includes:

[0075] I out =a1+a2*(I in ) 1 +a3*(I in ) 2 +a4*(I in ) 3 +…+a N *(I in ) N-1

[0076] Among them, I out I is the actual value of the sample current. in The sampled current values ​​are a1, a2, ..., a N Let be the coefficients of each term in the Nth degree polynomial.

[0077] Optionally, the value of N can be selected according to actual needs.

[0078] Step 203: Obtain the filament current sampling value.

[0079] The filament current sampling value is obtained by sampling the current of the X-ray tube filament under the bus voltage.

[0080] The X-ray tube, a core component of X-ray detection, is a vacuum diode operating at high voltage. An X-ray tube contains two electrodes: an anode and a cathode. The cathode is a filament that emits electrons, and the anode is a target that receives the electron bombardment. The power supply of the X-ray tube includes at least a low-voltage power supply to heat the filament and a high-voltage generator to apply high voltage to the electrodes. When a sufficient current flows through the tungsten filament to generate an electron cloud, and a sufficient voltage (in the kilovolt range) is applied between the anode and cathode, the electron cloud is drawn towards the anode. At this point, the electrons, at high energy and speed, collide with the tungsten target. Upon reaching the target surface, their motion is suddenly halted, and a small portion of their kinetic energy is converted into radiation energy, emitted as X-rays. This type of radiation is called bremsstrahlung.

[0081] Changing the filament current alters the filament temperature and electron emission, thereby changing the tube current and X-ray intensity. Currently, most X-ray tube filament power supply control is open-loop, lacking real-time feedback and resulting in poor control accuracy. Therefore, a more precise X-ray tube filament current control method is needed.

[0082] To control the filament current of the X-ray tube, it is first necessary to obtain a sampled value of the filament current. Optionally, the filament current under the bus voltage can be sampled using a current detection device.

[0083] The filament current sampling value corresponds to the bus voltage; that is, when the bus voltage changes, the filament current sampling value also changes.

[0084] Step 204: Based on the voltage mathematical model, process the sampled value of the filament current to obtain the predicted value of the filament current.

[0085] This voltage mathematical model is used to characterize the relationship between the sampled filament current value and the actual filament current on the filament of the X-ray tube.

[0086] Because the voltage mathematical model was trained to ensure that the predicted filament current value obtained from the filament current sampling values ​​is as close as possible to the actual filament current value on the X-ray tube filament, the predicted filament current value can reflect the actual filament current value on the X-ray tube filament.

[0087] Step 205: Based on the error between the predicted filament current and the target filament current, adjust the duty cycle of the drive signal of the half-bridge inverter circuit to regulate the filament current flowing through the X-ray tube.

[0088] The target filament current value can be preset according to actual needs.

[0089] By adjusting the duty cycle of the drive signal of the half-bridge inverter circuit, the predicted filament current value can be as close as possible to the target filament current value, and the predicted filament current value can reflect the actual filament current value on the filament of the X-ray tube, which is equivalent to adjusting the actual filament current value to the target filament current value.

[0090] In summary, in this application, an Nth-degree polynomial can be fitted using the sampled current value and the actual sampled current value to obtain the coefficients of the Nth-degree polynomial and construct a voltage mathematical model. This voltage mathematical model then represents the mapping relationship between the sampled value and the actual value of the filament current. Therefore, in actual operation, the sampled filament current value can be obtained first; then, based on the voltage mathematical model of the X-ray tube filament, the sampled filament current value can be processed to obtain the predicted filament current value; finally, based on the error between the predicted filament current value and the target filament current value, the duty cycle of the drive signal of the half-bridge inverter circuit can be adjusted to regulate the filament current flowing through the X-ray tube. Therefore, after obtaining the predicted filament current value that reflects the actual filament current on the X-ray tube filament, the above scheme can readjust the duty cycle of the drive signal of the half-bridge inverter circuit and re-obtain the sampled filament current value based on the predicted filament current value until the error between the predicted filament current value and the target filament current value reaches the required level, forming a closed-loop regulation and improving the accuracy of X-ray tube filament current control.

[0091] Figure 3 This is a flowchart illustrating a method for controlling the filament current of an X-ray tube according to an exemplary embodiment. This method can be applied to, for example... Figure 1 In the X-ray tube filament current control system, such as Figure 3 As shown, the X-ray tube filament current control method may include the following steps:

[0092] Step 301: Obtain N sample current values ​​and N sample current actual values.

[0093] Since the bus voltage value is not always fixed when the X-ray tube filament control system is working, it is necessary to obtain the total operating range of the bus voltage.

[0094] Furthermore, the total operating range of the bus voltage is divided into multiple intervals.

[0095] Optionally, the total operating range of the bus voltage can be divided into M equal parts according to each voltage endpoint, and the operating range of any one bus voltage can be selected; M≥2 and M is a positive integer.

[0096] Furthermore, within the operating range of the bus voltage, when N sample current actual values ​​flow through the X-ray lamp tube, the current of the X-ray tube filament is sampled to obtain N sample current sampling values.

[0097] Step 302: Based on the N sample current values ​​and the N sample current actual values, substitute them into the Nth degree polynomial for fitting operation to obtain the coefficients of each term of the Nth degree polynomial to construct a voltage mathematical model.

[0098] This voltage mathematical model is used to characterize the relationship between the sampled filament current value and the actual filament current on the filament of the X-ray tube.

[0099] The coefficients of this Nth-degree polynomial are obtained by fitting the sampled current values ​​with the actual sample current values. This Nth-degree polynomial includes different Nth-degree polynomials corresponding to each operating range of the bus voltage, and the coefficients of the Nth-degree polynomials corresponding to each operating range are different.

[0100] The voltage mathematical model is trained by using sampled current values ​​as input and actual sampled current values ​​as the target output. These sampled and actual sampled current values ​​are obtained under ideal conditions. Training the voltage mathematical model with these ideally obtained sampled and actual sampled current values ​​allows the model to predict a filament current value that is as close as possible to the actual filament current on the X-ray tube filament, thus accurately representing the relationship between the sampled filament current value and the actual filament current on the X-ray tube filament.

[0101] Optionally, the following Nth-degree polynomial can be used as the fitting formula between the sampled current value and the actual sample current value:

[0102] I out =a1+a2*(I in ) 1 +a3*(I in ) 2 +a4*(I in ) 3 +…+a N *(I in ) N-1

[0103] Where N≥2 and N is a positive integer, I out I is the actual value of the sample current. in The sampled current values ​​are a1, a2, ..., a N Let be the coefficients of each term in the Nth degree polynomial.

[0104] Optionally, the value of N can be selected according to actual needs.

[0105] For example, when N=3, the fitting formula is as follows:

[0106] I out=a1+a2*(I in ) 1 +a3*(I in ) 2 +a4*(I in ) 3

[0107] Given that the input and output (referring to the target value of the output) are known, the purpose of training this voltage mathematical model is to obtain the coefficients of each term of the Nth degree polynomial.

[0108] Since the relationship between the sampled filament current and the actual filament current on the X-ray tube filament changes when the bus voltage changes, different Nth-order polynomials corresponding to different bus voltages are required.

[0109] Therefore, training this voltage mathematical model requires sampled current values ​​and actual sampled current values ​​under different bus voltages. The operating range of the bus voltage in practical applications is divided into multiple operating ranges, and sampled current values ​​and actual sampled current values ​​are obtained for each of these ranges to train the voltage mathematical model.

[0110] Optionally, the plurality of operating ranges include a plurality of voltage endpoints; the coefficients of each Nth-degree polynomial corresponding to the plurality of operating ranges are obtained by fitting the sampled current value and the actual sample current value at the respective voltage endpoints where the bus voltage is located.

[0111] For example, the operating range M of the bus voltage is divided equally, denoted as [V0, V...]. M-1 Let each voltage terminal be V. i (i = 0, ..., M-1), where the value of M can be selected according to actual needs.

[0112] If the current bus voltage is at voltage endpoint V i The duty cycle of the PWM (Pulse Width Modulation) output of the drive module is D. i Four sets of sample current values ​​and actual sample current values ​​were selected, as follows:

[0113] I out1 =a i1 +a i2 *(I in1 ) 1 +a i3 *(I in1 ) 2 +a i4 *(I in1 ) 3

[0114] I out2 =a i1+a i2 *(I in2 ) 1 +a i3 *(I in3 ) 2 +a i4 *(I in2 ) 3

[0115] I out3 =a i1 +a i2 *(I in3 ) 1 +a i3 *(I in3 ) 2 +a i4 *(I in3 ) 3

[0116] I out4 =a i1 +a i2 *(I in4 ) 1 +a i3 *(I in4 ) 2 +a i4 *(I in4 ) 3

[0117] Among them, I out1 I out2 I out3 and I out4 These are the actual values ​​of the four sample currents, I in1 I in2 I in3 and I in4 a represents the sampled current values ​​corresponding to the actual values ​​of the four sample currents. i1 a i2 a i3 and a i4 These are the coefficients of the Nth degree polynomial under the current bus voltage.

[0118] Furthermore, the coefficients a of the Nth-degree polynomial under the current bus voltage are solved. i1 a i2 a i3 and a i4 .

[0119] Furthermore, by obtaining the coefficients of the Nth degree polynomials corresponding to i = 0, 1, ..., M-1 through the above steps, the coefficients of the Nth degree polynomials corresponding to each voltage endpoint within the bus voltage range can be obtained, which are the coefficients of each Nth degree polynomial corresponding to the multiple working ranges, thereby completing the training of the voltage mathematical model.

[0120] Step 303: Obtain the filament current sampling value.

[0121] The filament current sampling value is obtained by sampling the current of the X-ray tube filament under the bus voltage.

[0122] Optional, via Figure 1 The filament current acquisition module in the middle obtains the filament current sample value.

[0123] Optionally, the filament current can be sampled using a current acquisition device to obtain the filament current sampling value.

[0124] After training the voltage mathematical model, it can be used to predict the actual value of the filament current. When applying the voltage mathematical model, the sampled filament current value is used as the input. By substituting the sampled filament current value into the Nth-order polynomial corresponding to that value in the voltage mathematical model, the predicted filament current value can be output.

[0125] Step 304: Based on the Nth degree polynomial in the mathematical model of the X-ray tube filament voltage, select the target Nth degree polynomial for the working range where the bus voltage is located from among the Nth degree polynomials corresponding to multiple working ranges.

[0126] When applying the voltage mathematical model to obtain the predicted value of the filament current, the target Nth degree polynomial for the working range corresponding to the current bus voltage can be selected from the various Nth degree polynomials corresponding to multiple working ranges.

[0127] Optionally, when the voltage difference between the bus voltage and the target voltage endpoint among the plurality of voltage endpoints is less than or equal to the voltage threshold, the Nth degree polynomial corresponding to the target voltage endpoint is determined as the target Nth degree polynomial in the operating range of the bus voltage.

[0128] Optionally, when the voltage difference between the bus voltage and any of the multiple voltage endpoints is greater than a voltage threshold, the two voltage endpoints closest to the bus voltage are selected as candidate voltage endpoints.

[0129] The Nth degree polynomials of the two candidate voltage endpoints are determined as the target Nth degree polynomial.

[0130] In a possible case, if the current bus voltage is smaller than the minimum value of the operating range of the bus voltage in the voltage mathematical model, the minimum value of the operating range of the bus voltage is taken as the current bus voltage; if the current bus voltage is larger than the maximum value of the operating range of the bus voltage in the voltage mathematical model, the maximum value of the operating range of the bus voltage is taken as the current bus voltage.

[0131] For example, when V in ≤V0, in=0;when V in ≥V M-1 , in=M-1;when |V i -V in |≤Error, in=i;when V i <V in <V i+1 , i<in<i+1;wherein, i=0,…,M-1, V in is the current bus voltage, and Error is the voltage threshold.

[0132] Step 305: processing the filament current sampling value according to the target N-th order polynomial to obtain a predicted filament current value.

[0133] Optionally, processing the filament current sampling value respectively according to the two target N-th order polynomials to obtain two candidate filament current values;

[0134] determining the predicted filament current value according to the voltage values of the two voltage endpoints closest to the bus voltage and the two candidate filament current values.

[0135] For example, when V in ≤V0, I out =a 01 +a 02 *(I in ) 1 +a 03 *(I in ) 2 +a 04 *(I in ) 3 ;

[0136] When V in ≥V M-1 , I out =a (M-1)1 +a (M-1)2 *(I in ) 1 +a (M-1)3 *(I in ) 2 +a (M-1)4 *(I in ) 3 ;

[0137] When in = i, I out = a i1 + a i2 *I in + a i3 *I in *I in + a i4 *I in *I in *I in ;

[0138] When i < in < i+1, I i = a i1 + a i2 *I in + a i3 *I in *I in + a i4 *I in *I in *I in ,

[0139] I i+1 = a (i+1)1 + a (i+1)2 *I in + a (i+1)3 *I in *I in + a (i+1)4 *I in *I in *I in ,

[0140] I out = (V in - V i )*(I i+1 - I i ) / (V i+1 - V i )+ I i .

[0141] wherein, I i is the predicted filament current at the i-th voltage endpoint, a i1 , a i2 , a i3 and a i4 are N-th degree polynomial coefficients corresponding to I i , V i is the bus voltage value corresponding to I i , I i+1 is the predicted filament current at the (i+1)-th voltage endpoint, a (i+1)1 , a (i+1)2 , a(i+1)3 and a (i+1)4 For I i+1 The corresponding coefficients of the Nth degree polynomial, V i+1 For I i+1 The corresponding bus voltage value, I in I is the current filament current sampling value. out V is the predicted value of the current filament current. in This is the current bus voltage value.

[0142] Step 306: Based on the error between the predicted filament current and the target filament current, adjust the duty cycle of the drive signal of the half-bridge inverter circuit to regulate the filament current flowing through the X-ray tube.

[0143] The target filament current value can be determined based on actual needs, through... Figure 1 The filament current setting module is preset.

[0144] By adjusting the duty cycle of the drive signal of the half-bridge inverter circuit, the predicted filament current value can be as close as possible to the target filament current value, and the predicted filament current value can reflect the actual filament current value on the filament of the X-ray tube, which is equivalent to adjusting the actual filament current value to the target filament current value.

[0145] For example, Figure 4 A flowchart illustrating an example of an X-ray tube filament current control method according to an embodiment of this application is shown. The target current value I... ref Corresponding to the target filament current value, filament current I fd Corresponding to the predicted filament current, I' fd The corresponding filament current sampling value, ΔI corresponds to the error between the predicted filament current value and the target filament current value.

[0146] In summary, in this application, an Nth-degree polynomial can be fitted using the sampled current value and the actual sampled current value to obtain the coefficients of the Nth-degree polynomial and construct a voltage mathematical model. This voltage mathematical model then represents the mapping relationship between the sampled value and the actual value of the filament current. Therefore, in actual operation, the sampled filament current value can be obtained first; then, based on the voltage mathematical model of the X-ray tube filament, the sampled filament current value can be processed to obtain the predicted filament current value; finally, based on the error between the predicted filament current value and the target filament current value, the duty cycle of the drive signal of the half-bridge inverter circuit can be adjusted to regulate the filament current flowing through the X-ray tube. Therefore, after obtaining the predicted filament current value that reflects the actual filament current on the X-ray tube filament, the above scheme can readjust the duty cycle of the drive signal of the half-bridge inverter circuit and re-obtain the sampled filament current value based on the predicted filament current value until the error between the predicted filament current value and the target filament current value reaches the required level, forming a closed-loop regulation and improving the accuracy of X-ray tube filament current control.

[0147] Figure 5 This is a structural block diagram illustrating an X-ray tube filament current control device according to an exemplary embodiment. The X-ray tube filament current control device includes:

[0148] The sample acquisition module 501 is used to acquire N sample current sampling values ​​and N sample current actual values; the sample current sampling value is the current obtained by sampling the current of the X-ray tube filament when the sample current actual value flows through the X-ray tube filament under the bus voltage.

[0149] The fitting module 502 is used to perform a fitting operation by substituting the N sample current sampling values ​​and the N sample current actual values ​​into an Nth degree polynomial to obtain the coefficients of the Nth degree polynomial in order to construct a voltage mathematical model.

[0150] The data acquisition module 503 is used to acquire the filament current sampling value; the filament current sampling value is obtained by sampling the current of the X-ray tube filament under the bus voltage;

[0151] The current prediction module 504 is used to process the sampled value of the filament current according to the voltage mathematical model to obtain the predicted value of the filament current.

[0152] The current adjustment module 505 is used to adjust the duty cycle of the drive signal of the half-bridge inverter circuit according to the error between the predicted value of the filament current and the target filament current value, so as to adjust the filament current flowing through the X-ray tube.

[0153] The Nth degree polynomial includes:

[0154] I out=a1+a2*(I in ) 1 +a3*(I in ) 2 +a4*(I in ) 3 +…+a N *(I in ) N-1

[0155] Among them, I out I is the actual value of the sample current. in The sampled current values ​​are a1, a2, ..., a N Let be the coefficients of each term in the Nth degree polynomial.

[0156] In one possible implementation, the voltage mathematical model includes an Nth-degree polynomial; the coefficients of the Nth-degree polynomial are obtained by fitting the sampled current values ​​with the actual sample current values.

[0157] Based on the mathematical model of the X-ray tube filament voltage, the sampled filament current values ​​are processed to obtain predicted filament current values, including:

[0158] Based on this Nth-degree polynomial, the sampled value of the filament current is processed to obtain the predicted value of the filament current.

[0159] In one possible implementation, the sampled filament current value is processed according to the Nth-degree polynomial to obtain a predicted filament current value, including:

[0160] Among the Nth degree polynomials corresponding to multiple operating ranges, select the target Nth degree polynomial for the operating range where the bus voltage is located;

[0161] Based on the target Nth degree polynomial, the sampled value of the filament current is processed to obtain the predicted value of the filament current.

[0162] In one possible implementation, the total operating range of the bus voltage can also be obtained;

[0163] Divide the total operating range of the bus voltage into M equal parts according to each voltage endpoint, and select the operating range of any one bus voltage.

[0164] Within the operating range of the bus voltage, when N sample current actual values ​​flow through the X-ray tube filament, the current of the X-ray tube filament is sampled to obtain N sample current sampling values.

[0165] In one possible implementation, among the Nth-degree polynomials corresponding to multiple operating ranges, a target Nth-degree polynomial for the operating range where the bus voltage is located is selected, including:

[0166] When the voltage difference between the bus voltage and the target voltage endpoint among the multiple voltage endpoints is less than or equal to the voltage threshold, the Nth degree polynomial corresponding to the target voltage endpoint is determined as the target Nth degree polynomial in the operating range of the bus voltage.

[0167] In one possible implementation, among the Nth-degree polynomials corresponding to multiple operating ranges, a target Nth-degree polynomial for the operating range where the bus voltage is located is selected, including:

[0168] When the voltage difference between the bus voltage and any of the multiple voltage endpoints is greater than the voltage threshold, the two voltage endpoints closest to the bus voltage are selected as candidate voltage endpoints.

[0169] The Nth degree polynomials of the two candidate voltage endpoints are determined as the target Nth degree polynomial.

[0170] In one possible implementation, the sampled filament current value is processed according to the Nth-degree polynomial to obtain a predicted filament current value, including:

[0171] The filament current sample value is processed using an Nth-degree polynomial from the two candidate voltage endpoints and the following formula to obtain the predicted filament current value:

[0172] I i =a i1 +a i2 *I in +a i3 *I in *I in +a i4 *I in *I in *I in ;

[0173] I i+1 =a (i+1)1 +a (i+1)2 *I in +a (i+1)3 *I in *I in +a (i+1)4 *I in *I in *I in ;

[0174] I out =(V in -V i )*(I i+1 -I i ) / (V i+1 -V i )+I i ;

[0175] Among them, I i Let a be the predicted value of the filament current at the i-th voltage endpoint. i1 a i2 a i3 and a i4 For I i The corresponding coefficients of the Nth degree polynomial, V i For I i The corresponding bus voltage value, I i+1 Let a be the predicted value of the filament current at the (i+1)th voltage endpoint. (i+1)1 a (i+1)2 a (i+1)3 and a (i+1)4 For I i+1 The corresponding coefficients of the Nth degree polynomial, V i+1 For I i+1 The corresponding bus voltage value, I in I is the current filament current sampling value. out V is the predicted value of the current filament current. in This is the current bus voltage value.

[0176] In summary, in this application, an Nth-degree polynomial can be fitted using the sampled current value and the actual sampled current value to obtain the coefficients of the Nth-degree polynomial and construct a voltage mathematical model. This voltage mathematical model then represents the mapping relationship between the sampled value and the actual value of the filament current. Therefore, in actual operation, the sampled filament current value can be obtained first; then, based on the voltage mathematical model of the X-ray tube filament, the sampled filament current value can be processed to obtain the predicted filament current value; finally, based on the error between the predicted filament current value and the target filament current value, the duty cycle of the drive signal of the half-bridge inverter circuit can be adjusted to regulate the filament current flowing through the X-ray tube. Therefore, after obtaining the predicted filament current value that reflects the actual filament current on the X-ray tube filament, the above scheme can readjust the duty cycle of the drive signal of the half-bridge inverter circuit and re-obtain the sampled filament current value based on the predicted filament current value until the error between the predicted filament current value and the target filament current value reaches the required level, forming a closed-loop regulation and improving the accuracy of X-ray tube filament current control.

[0177] Figure 6A structural block diagram of a computer device 600 illustrated in an exemplary embodiment of this application is shown. This computer device can be implemented as a server as described above in this application. The computer device 600 includes a Central Processing Unit (CPU) 601, a system memory 604 including Random Access Memory (RAM) 602 and Read-Only Memory (ROM) 603, and a system bus 605 connecting the system memory 604 and the CPU 601. The computer device 600 also includes a mass storage device 606 for storing an operating system 609, application programs 610, and other program modules 611.

[0178] The mass storage device 606 is connected to the central processing unit 601 via a mass storage controller (not shown) connected to the system bus 605. The mass storage device 606 and its associated computer-readable media provide non-volatile storage for the computer device 600. That is, the mass storage device 606 may include computer-readable media (not shown) such as a hard disk or a compact disc read-only memory (CD-ROM) drive.

[0179] Without loss of generality, the computer-readable medium may include computer storage media and communication media. Computer storage media include volatile and non-volatile, removable and non-removable media implemented using any method or technology for storing information such as computer-readable instructions, data structures, program modules, or other data. Computer storage media include RAM, ROM, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other solid-state storage technologies, CD-ROM, digital versatile disc (DVD) or other optical storage, magnetic tape cassettes, magnetic tape, disk storage, or other magnetic storage devices. Of course, those skilled in the art will recognize that the computer storage media are not limited to the above-mentioned types. The system memory 604 and mass storage device 606 described above can be collectively referred to as memory.

[0180] According to various embodiments of this disclosure, the computer device 600 can also be connected to a remote computer on a network, such as the Internet. That is, the computer device 600 can be connected to a network 608 via a network interface unit 607 connected to the system bus 605, or it can use the network interface unit 607 to connect to other types of networks or remote computer systems (not shown).

[0181] The memory also includes at least one computer program stored in the memory, and the central processing unit 601 executes the at least one computer program to implement all or part of the steps in the methods shown in the above embodiments.

[0182] In one exemplary embodiment, a computer-readable storage medium is also provided for storing at least one computer program, which is loaded and executed by a processor to implement all or part of the steps in the above-described method. For example, the computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a compact disc read-only memory (CD-ROM), magnetic tape, floppy disk, or optical data storage device, etc.

[0183] In one exemplary embodiment, a computer program product or computer program is also provided, comprising computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the aforementioned actions. Figure 2 or Figure 3 All or part of the steps of the method shown in any embodiment.

[0184] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0185] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for controlling the filament current of an X-ray tube, characterized in that, This system is applied to an X-ray tube filament current control system. The system includes a bus voltage source, an inverter module, a filament transformer, a filament current acquisition module, an X-ray tube, a CPU, a drive module, and a bus voltage sampling module. The inverter module converts the bus voltage provided by the bus voltage source from a DC voltage signal to an AC voltage signal. The filament transformer converts the AC voltage signal into a secondary AC voltage signal to act on the X-ray tube. The filament current acquisition module acquires the primary current of the filament transformer and processes it to obtain a DC filament current signal. The filament current acquisition module includes a current transformer and a rectifier module. The current transformer isolates the AC voltage signal from the CPU control loop and acquires the primary current of the filament transformer, converting it into a secondary AC current signal through a gate ratio. The rectifier module performs full-wave rectification on the secondary AC current signal to obtain a DC filament current signal. The CPU calculates the effective value of the DC filament current signal and dynamically adjusts the duty cycle of the PWM based on the difference between the effective value of the DC filament current signal and a preset target current value, sending a drive signal to the drive module. The drive module is used to process the drive signal into a control signal for the inverter module, so as to control the inverter module to adjust the duty cycle during the inverter process. The method includes: Obtain N sampled values ​​of filament current and N actual values ​​of filament current; the sampled values ​​of filament current are obtained by sampling the current of the X-ray tube filament based on the current transformer and rectifier module when the actual values ​​of the filament current flow through the X-ray tube filament under the bus voltage; N≥2 and N is a positive integer; wherein, obtain the total operating range of the bus voltage; divide the total operating range of the bus voltage into M equal parts according to each voltage endpoint, and select any one operating range of the bus voltage; under the operating range of the bus voltage, when the actual values ​​of the N sampled values ​​of filament current flow through the X-ray tube filament, sample the current of the X-ray tube filament respectively to obtain N sampled values ​​of filament current; Based on the sampled values ​​of the N filament current samples and the actual values ​​of the N filament current samples, the Nth degree polynomial is substituted into the Nth degree polynomial for fitting operation to obtain the coefficients of each term of the Nth degree polynomial to construct a voltage mathematical model. Obtain the filament current sampling value; the filament current sampling value is obtained by sampling the current of the X-ray tube filament under the bus voltage; According to the voltage mathematical model, the sampled filament current values ​​are processed to obtain the predicted filament current values; wherein, among the Nth degree polynomials corresponding to multiple operating ranges, the target Nth degree polynomial for the operating range where the bus voltage is located is selected; and the sampled filament current values ​​are processed according to the target Nth degree polynomial to obtain the predicted filament current values. Based on the error between the predicted filament current and the target filament current, the duty cycle of the drive signal of the half-bridge inverter circuit is adjusted to regulate the filament current flowing through the X-ray tube. The Nth degree polynomial includes: I out =a1+a2 (I in ) 1 +a3 (I in ) 2 +a4 (I in ) 3 +…+a N (I in ) N-1 Among them, I out I represents the actual value of the filament current sample. in These are the sampled values ​​of the filament current, a1, a2, ..., a N Let be the coefficients of the Nth degree polynomial.

2. The method according to claim 1, characterized in that, The voltage mathematical model includes an Nth-degree polynomial; the coefficients of the Nth-degree polynomial are obtained by fitting the sampled values ​​of the filament current sample with the actual values ​​of the filament current sample. The step of processing the sampled filament current value according to the voltage mathematical model to obtain the predicted filament current value includes: The sampled filament current values ​​are processed according to the Nth degree polynomial to obtain the predicted filament current values.

3. The method according to claim 2, characterized in that, Among the Nth-degree polynomials corresponding to multiple operating ranges, the target Nth-degree polynomial for the operating range where the bus voltage is located is selected, including: When the voltage difference between the bus voltage and the target voltage endpoint among the plurality of voltage endpoints is less than or equal to the voltage threshold, the Nth degree polynomial corresponding to the target voltage endpoint is determined as the target Nth degree polynomial in the operating range of the bus voltage.

4. The method according to claim 2, characterized in that, Among the Nth-degree polynomials corresponding to multiple operating ranges, the target Nth-degree polynomial for the operating range where the bus voltage is located is selected, including: When the voltage difference between the bus voltage and any of the plurality of voltage endpoints is greater than the voltage threshold, the two voltage endpoints closest to the bus voltage are selected as candidate voltage endpoints. The Nth degree polynomials of the two candidate voltage endpoints are determined as the target Nth degree polynomial.

5. The method according to claim 4, characterized in that, Based on the Nth-degree polynomial, the sampled filament current values ​​are processed to obtain predicted filament current values, including: The filament current sample value is processed using an Nth-degree polynomial from the two candidate voltage endpoints and the following formula to obtain the predicted filament current value: I i =a i1 +a i2 I in +a i3 I in I in +a i4 I in I in I in ; I i+1 =a (i+1)1 +a (i+1)2 I in +a (i+1)3 I in I in +a (i+1)4 I in I in I in ; I out =(V in -V i ) (I i+1 -I i ) / (V i+1 -V i )+I i ; Among them, I i Let a be the predicted value of the filament current at the i-th voltage endpoint. i1 a i2 a i3 and a i4 For I i The corresponding coefficients of the Nth degree polynomial, V i For I i The corresponding bus voltage value, I i+1 Let a be the predicted value of the filament current at the (i+1)th voltage endpoint. (i+1)1 a (i+1)2 a (i+1)3 and a (i+1)4 For I i+1 The corresponding coefficients of the Nth degree polynomial, V i+1 For I i+1 The corresponding bus voltage value, I in I is the current filament current sampling value. out V is the predicted value of the current filament current. in This is the current bus voltage value.

6. A device for controlling the filament current of an X-ray tube, characterized in that, This system is applied to an X-ray tube filament current control system. The system includes a bus voltage source, an inverter module, a filament transformer, a filament current acquisition module, an X-ray tube, a CPU, a drive module, and a bus voltage sampling module. The inverter module converts the bus voltage provided by the bus voltage source from a DC voltage signal to an AC voltage signal. The filament transformer converts the AC voltage signal into a secondary AC voltage signal to act on the X-ray tube. The filament current acquisition module acquires the primary current of the filament transformer and processes it to obtain a DC filament current signal. The filament current acquisition module includes a current transformer and a rectifier module. The current transformer isolates the AC voltage signal from the CPU control loop and acquires the primary current of the filament transformer, converting it into a secondary AC current signal through a gate ratio. The rectifier module performs full-wave rectification on the secondary AC current signal to obtain a DC filament current signal. The CPU calculates the effective value of the DC filament current signal and dynamically adjusts the duty cycle of the PWM based on the difference between the effective value of the DC filament current signal and a preset target current value, sending a drive signal to the drive module. The drive module is used to process the drive signal into a control signal for the inverter module, so as to control the inverter module to adjust the duty cycle during the inverter process. The device includes: The sample acquisition module is used to acquire N filament current sample values ​​and N filament current sample actual values. The filament current sample values ​​are the currents obtained by sampling the X-ray tube filament current based on the current transformer and rectifier module when the actual filament current sample values ​​flow through the X-ray tube filament under the bus voltage. N ≥ 2 and N is a positive integer. The module acquires the total operating range of the bus voltage. The total operating range of the bus voltage is divided into M equal parts according to each voltage endpoint, and the operating range of any one bus voltage is selected. Under the operating range of the bus voltage, when N filament current sample actual values ​​flow through the X-ray tube filament, the current of the X-ray tube filament is sampled to obtain N filament current sample values. The fitting module is used to substitute the sampled values ​​of the N filament current samples and the actual values ​​of the N filament current samples into an Nth-degree polynomial to perform a fitting operation, and obtain the coefficients of each term of the Nth-degree polynomial to construct a voltage mathematical model. The data acquisition module is used to acquire the filament current sampling value; the filament current sampling value is obtained by sampling the current of the X-ray tube filament under the bus voltage; The current prediction module is used to process the sampled filament current value according to the voltage mathematical model to obtain the predicted filament current value; wherein, among the Nth degree polynomials corresponding to multiple working ranges, the target Nth degree polynomial of the working range where the bus voltage is located is selected; and the sampled filament current value is processed according to the target Nth degree polynomial to obtain the predicted filament current value. The current regulation module is used to adjust the duty cycle of the drive signal of the half-bridge inverter circuit according to the error between the predicted value of the filament current and the target value of the filament current, so as to regulate the filament current flowing through the X-ray tube. The Nth degree polynomial includes: I out =a 01 +a 02 (I in ) 1 +a 03 (I in ) 2 +a 04 (I in ) 3 +…+a N (I in ) N-1 Among them, I in I represents the sampled value of the filament current. out a is the actual value of the filament current sample. 01 ,a 02 ,a 03 ,a 04 ,…, a N The coefficients are those of an Nth-degree polynomial.

7. A computer device, characterized in that, The computer device includes a processor and a memory, the memory storing at least one instruction, which is loaded and executed by the processor to implement the X-ray tube filament current control method as described in any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The storage medium stores at least one instruction, which is loaded and executed by a processor to implement the X-ray tube filament current control method as described in any one of claims 1 to 5.

Images