Power supply control system for x-ray tube filament switching, x-ray tube, x-ray imaging system and filament switching control method

Abstract

The application discloses a power supply control system for X-ray tube filament switching, an X-ray tube, an X-ray imaging system and a filament switching control method. The power supply control system comprises a PFC circuit and a double half-bridge topology circuit. The PFC circuit comprises a PFC switch tube, a PFC control chip and sequentially connected inductance, a freewheeling diode and a filter capacitor. The chip controls the duty cycle of the PFC switch tube to keep the voltage across the filter capacitor at a preset value. The double half-bridge topology circuit comprises a first branch where a first energy storage capacitor and a second energy storage capacitor are located, a second branch where a first controllable switch and a second controllable switch are located, and a third branch where a third controllable switch and a fourth controllable switch are located. A first filament is arranged between the first branch and the second branch, and a second filament is arranged between the first branch and the third branch. The application provides an X-ray tube cathode filament driving scheme which can realize independent heating control of large and small filaments and does not interrupt filament preheating during focal point switching.

Description

Technical Field

[0001] This invention relates to the field of X-ray imaging, and more particularly to a power control system for switching the filament of an X-ray tube, an X-ray tube, an X-ray imaging system, and a filament switching control method. Background Technology

[0002] X-ray imaging systems are widely used in medical diagnosis, industrial non-destructive testing, and security inspection. The X-ray tube, as the core component of the system, typically has a filament structure in its cathode assembly. Heating the filament causes it to emit electrons, which are then accelerated under high voltage at the anode to bombard the anode target surface, generating X-rays. To adapt to the varying spatial resolution and radiation dose requirements of different imaging scenarios, X-ray tubes generally employ a dual-focal design, with a large filament and a small filament in the cathode assembly. These correspond to a large focal mode (suitable for fluoroscopy and wide-field imaging, requiring higher tube current) and a small focal mode (suitable for high-resolution radiography and imaging of fine structures, requiring lower tube current), respectively.

[0003] The filament drive circuit of a dual-focus X-ray tube typically employs a mechanical relay or analog switch switching scheme. This scheme uses a half-bridge or full-bridge circuit to power a single filament, with a mechanical relay or semiconductor analog switch connected in series in both the large and small filament circuits. The on / off state of these switches selects the currently operating filament. When a large focal spot is needed, the large filament circuit switch is closed and the small filament circuit switch is open; when a small focal spot is needed, the small filament circuit switch is closed and the large filament circuit switch is open. However, this scheme has the following drawbacks: First, mechanical relays suffer from contact wear, slow response speed, and low reliability, and are prone to failure, especially in frequent switching scenarios. Second, semiconductor analog switches have on-resistance, parasitic capacitance, and leakage current, which affect the precise control and stability of the filament current. Third, the filament disconnected during switching is in a completely de-energized state, causing a sharp drop in filament temperature, requiring a long warm-up time when restarted, affecting system response speed and imaging efficiency.

[0004] The disclosure of the above background technical content is only for the purpose of assisting in understanding the concept and technical solution of this application, and does not necessarily provide technical instruction. Summary of the Invention

[0005] The purpose of this invention is to provide an X-ray tube cathode filament driving scheme that enables independent heating control of the large and small filaments and does not interrupt filament preheating during focus switching.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A power control system for switching X-ray tube filaments is provided for switching the first and second filaments of an X-ray tube under different focal modes without physically disconnecting either filament. The system includes a PFC circuit and a dual half-bridge topology circuit. The PFC circuit includes an inductor, a freewheeling diode, a filter capacitor, a PFC switch, and a PFC control chip. The inductor, freewheeling diode, and filter capacitor are connected in sequence. The PFC switch is located across the freewheeling diode and the filter capacitor. The PFC control chip is configured to control the duty cycle of the PFC switch to maintain a preset voltage value across the filter capacitor. The dual half-bridge topology circuit includes a first branch, a second branch, and a third branch connected in parallel with the filter capacitor. The first branch includes a first energy storage capacitor and a second energy storage capacitor connected in series. The second branch includes a first controllable switch and a second controllable switch connected in series. The third branch includes a third controllable switch and a fourth controllable switch connected in series. A first connection node is configured between the first energy storage capacitor and the second energy storage capacitor, which is configured to connect one end of the first filament and the second filament respectively; a second connection node is configured between the first controllable switch and the second controllable switch, which is configured to connect the other end of the first filament; a third connection node is configured between the third controllable switch and the fourth controllable switch, which is configured to connect the other end of the second filament.

[0007] Furthermore, based on any one or a combination of the aforementioned technical solutions, the duty cycles of the first controllable switch, the second controllable switch, the third controllable switch, and the fourth controllable switch are adjustable; The first controllable switch and the second controllable switch are turned on alternately, and the third controllable switch and the fourth controllable switch are turned on alternately.

[0008] Furthermore, following any one or a combination of the aforementioned technical solutions, the control channels of the second branch and the third branch are decoupled from each other.

[0009] Furthermore, based on any one or a combination of the aforementioned technical solutions, the PWM duty cycles of the first controllable switch and the second controllable switch are synchronously adjusted and consistent, and this is defined as the first PWM duty cycle; The PWM duty cycles of the third and fourth controllable switches are synchronously adjusted and consistent, and are defined as the second PWM duty cycle. The duty cycle of the first PWM and the duty cycle of the second PWM are both greater than 0 and do not exceed 50%, and there is a difference between the two.

[0010] Furthermore, following any one or a combination of the aforementioned technical solutions, when switching to the first filament, the first PWM duty cycle and the second PWM duty cycle are adjusted synchronously, and the adjusted first PWM duty cycle is greater than the second PWM duty cycle. When switching to the second filament, the duty cycle of the first PWM and the duty cycle of the second PWM are adjusted synchronously, and the adjusted duty cycle of the second PWM is greater than the duty cycle of the first PWM.

[0011] Furthermore, following any one or a combination of the aforementioned technical solutions, when switching to the first filament, the first PWM duty cycle is adjusted within the range of 15% to 50%, and the second PWM duty cycle is simultaneously adjusted within the range of 0.1% to 8%. When switching to the second filament, the duty cycle of the second PWM is adjusted within the range of 15% to 50%, while the duty cycle of the first PWM is adjusted simultaneously within the range of 0.1% to 8%.

[0012] Furthermore, following any one or a combination of the aforementioned technical solutions, the first energy storage capacitor and the second energy storage capacitor have the same capacitance value.

[0013] Furthermore, based on any one or a combination of the aforementioned technical solutions, the ratio of the capacitance of the filter capacitor to the capacitance of the first energy storage capacitor is between 10:1 and 500:1.

[0014] Furthermore, following any or a combination of the aforementioned technical solutions, the negative terminal of the freewheeling diode is connected to the upper plate of the filter capacitor; The PFC switch is an NMOS transistor, with its drain connected to the positive terminal of the freewheeling diode and its source connected to the lower plate of the filter capacitor.

[0015] Furthermore, in accordance with any one or a combination of the aforementioned technical solutions, the first controllable switch, the second controllable switch, the third controllable switch, and the fourth controllable switch are all NMOS transistors; The drains of the first and third controllable switches are both connected to the upper plate of the filter capacitor; the source of the first controllable switch is connected to the drain of the second controllable switch, and the source of the third controllable switch is connected to the drain of the fourth controllable switch; the sources of the second and fourth controllable switches are both connected to the lower plate of the filter capacitor.

[0016] According to another aspect of the present invention, an X-ray tube is provided, comprising a cathode assembly, an anode target, and a housing with an internal vacuum, the cathode assembly comprising a first filament and a second filament for emitting electrons, and the X-ray tube further comprising a power control system as described above.

[0017] According to another aspect of the present invention, an X-ray imaging system is provided, comprising a high-voltage generator, a detector, an image processing unit, and an X-ray tube as described above, wherein the high-voltage generator is configured to provide an anode high voltage and a filament driving power supply to the X-ray tube, the detector is configured to receive X-rays passing through the subject and convert them into electrical signals, and the image processing unit is configured to reconstruct an image based on the electrical signals.

[0018] Furthermore, in accordance with any or a combination of the aforementioned technical solutions, the system further includes a filament switching control configured to send a command to the X-ray tube to switch the filament. In response to the command to switch from the first filament to the second filament, the duty cycles of the first, second, third, and fourth controllable switches of the X-ray tube synchronous adjustment power control system are adjusted so that the duty cycles of the first and second controllable switches are greater than 0 and less than the duty cycles of the third and fourth controllable switches. In response to the command to switch from the second filament to the first filament, the duty cycles of the first, second, third, and fourth controllable switches of the X-ray tube synchronous adjustment power control system are adjusted so that the duty cycles of the third and fourth controllable switches are greater than 0 and less than the duty cycles of the first and second controllable switches.

[0019] According to another aspect of the present invention, an X-ray tube filament switching control method based on the power control system described above is provided, which switches the filament without shutting down the exposure through the following steps: The first filament of the X-ray tube is connected between the first connection node and the second connection node of the power control system, and the second filament of the X-ray tube is connected between the first connection node and the third connection node of the power control system. An external AC power source is connected to the input terminal of the power control system so that the external AC power source forms a circuit with the inductor, freewheeling diode, and filter capacitor. In response to the command to switch from the first filament to the second filament, the duty cycles of the first controllable switch, the second controllable switch, the third controllable switch and the fourth controllable switch of the power control system are synchronously adjusted so that the duty cycles of the first controllable switch and the second controllable switch are greater than 0 and less than the duty cycles of the third controllable switch and the fourth controllable switch. In response to the command to switch from the second filament to the first filament, the duty cycles of the first, second, third, and fourth controllable switches of the power control system are synchronously adjusted so that the duty cycles of the third and fourth controllable switches are greater than 0 and less than the duty cycles of the first and second controllable switches.

[0020] The beneficial effects of the technical solution provided by this invention are as follows: a. Coordinate and optimize the design between the pre-stage power factor correction (PFC) circuit and the post-stage filament drive circuit of the X-ray tube filament drive circuit, and make full use of the flexibility of the bus voltage to achieve decoupled control and independent current regulation of the two filaments; b. An X-ray tube cathode filament drive scheme that achieves independent heating control of large and small filaments, uninterrupted filament preheating during focus switching, balanced filament life, and fast response speed; c. Provide an independent half-bridge structure for power supply to each filament, eliminating the need for relays and avoiding failures caused by relay aging; d. Using a dual half-bridge topology allows two filaments to work simultaneously, with one filament in a state of constant switching, reducing filament switching time and eliminating the need to stop exposure when switching filaments; e. Using PFC as the preamplifier circuit can adapt to different voltage levels in different regions, ensuring operational stability under different voltage levels and guaranteeing the accuracy of filament current calibration. Attached Figure Description

[0021] 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 recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A circuit diagram of a power control system for switching X-ray tube filaments, provided as an exemplary embodiment of the present invention; Figure 2 A schematic diagram of the current path of the control channel of the second branch where the first controllable switch and the second controllable switch are located, provided as an exemplary embodiment of the present invention; Figure 3 A schematic diagram of the current path of the control channel of the third branch where the third and fourth controllable switches are located, provided as an exemplary embodiment of the present invention; Figure 4 A schematic block diagram of an X-ray imaging system provided as an exemplary embodiment of the present invention; Figure 5 A flowchart illustrating an exemplary embodiment of the present invention provides a method for switching X-ray tube filaments. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, apparatus, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0025] In one embodiment of the present invention, a power control system for switching X-ray tube filaments is provided, for switching the first and second filaments of the X-ray tube under different focal modes without physically disconnecting either filament. The system includes a PFC circuit and a dual half-bridge topology circuit, such as... Figure 1 As shown, the PFC circuit includes an inductor L1, a freewheeling diode D1, a filter capacitor C3, a PFC switch Q5, and a PFC control chip (not shown). The inductor L1, freewheeling diode D1, and filter capacitor C3 are connected in sequence. The PFC switch Q5 is located across the freewheeling diode D1 and the filter capacitor C3: the negative terminal of the freewheeling diode D1 is connected to the upper plate of the filter capacitor C3; the PFC switch Q5 is an NMOS transistor, with its drain connected to the positive terminal of the freewheeling diode D1 and its source connected to the lower plate of the filter capacitor C3. The PFC control chip is configured to control the duty cycle of the PFC switch Q5 so that the voltage across the filter capacitor C3 is maintained at a preset value (bus voltage). The first energy storage capacitor C1 and the second energy storage capacitor C2 have the same capacitance value; the ratio of the capacitance value of the filter capacitor C3 to the capacitance value of the first energy storage capacitor C1 (or the second energy storage capacitor C2) is between 10:1 and 500:1.

[0026] Using a PFC circuit as the preamplifier circuit can adapt to different voltage levels in different regions, ensuring operational stability under different voltage levels and guaranteeing the accuracy of filament current calibration.

[0027] See also Figure 1 The dual half-bridge topology circuit includes a first branch, a second branch, and a third branch connected in parallel with the filter capacitor C3. The first branch includes a first energy storage capacitor C1 and a second energy storage capacitor C2 connected in series. The second branch includes a first controllable switch Q1 and a second controllable switch Q2 connected in series. The third branch includes a third controllable switch Q3 and a fourth controllable switch Q4 connected in series. Here, the dual half-bridge structure supplies power to both the first and second filaments.

[0028] A first connection node is configured between the first energy storage capacitor C1 and the second energy storage capacitor C2, which is configured to connect one end of the first filament LF and the second filament SF respectively; a second connection node is configured between the first controllable switch Q1 and the second controllable switch Q2, which is configured to connect the other end of the first filament LF; a third connection node is configured between the third controllable switch Q3 and the fourth controllable switch Q4, which is configured to connect the other end of the second filament SF.

[0029] The first filament LF and the second filament SF have different electrical parameters, so as to Figure 1 In the example embodiment, the first filament is a large filament with a longer, thicker tungsten wire and more spiral turns. Its projected electron emission surface on the cathode surface is large, creating a large focal point when it strikes the anode target. The second filament is a small filament with a shorter, thinner tungsten wire and fewer spiral turns. Its projected electron emission surface on the cathode surface is small, creating a small focal point when it strikes the anode target. Therefore, the large filament is suitable for high-dose-rate fluoroscopic / wide-field-of-view imaging requirements, while the small filament is suitable for high-spatial-resolution imaging of fine structures.

[0030] In one specific embodiment, the first controllable switch Q1, the second controllable switch Q2, the third controllable switch Q3, and the fourth controllable switch Q4 are all NMOS transistors; The drains of the first controllable switch Q1 and the third controllable switch Q3 are both connected to the upper plate of the filter capacitor C3; the source of the first controllable switch Q1 is connected to the drain of the second controllable switch Q2, and the source of the third controllable switch Q3 is connected to the drain of the fourth controllable switch Q4; the sources of the second controllable switch Q2 and the fourth controllable switch Q4 are both connected to the lower plate of the filter capacitor C3. In this configuration, the first controllable switch and the second controllable switch are alternately turned on, and the third controllable switch and the fourth controllable switch are alternately turned on. The control channels of the second branch and the third branch are decoupled from each other, meaning that the switching states of the first / second controllable switch and the third / fourth controllable switch are independent. In other words, when the first controllable switch Q1 is turned on, the third controllable switch Q3 or the fourth controllable switch Q4 can also be turned on.

[0031] It is certain that both the first and second filaments carry current. Based on exposure requirements, one filament is designated as the primary filament, and the other as the secondary filament. A small current is controlled to flow through the secondary filament. In this configuration, the tube current in the corresponding branch is negligible. When switching filaments, there is no need to shut down the exposure; simply adjusting the tube current in the second and third branches is sufficient, ensuring high efficiency and stability for each exposure. This method also eliminates the need for separate relays for each filament, preventing malfunctions caused by relay aging.

[0032] The duty cycles of the first controllable switch Q1, the second controllable switch Q2, the third controllable switch Q3, and the fourth controllable switch Q4 are adjustable. Specifically, during the filament switching process, the PWM duty cycles of the first and second controllable switches are adjusted synchronously and identically, defined as the first PWM duty cycle; the PWM duty cycles of the third and fourth controllable switches are adjusted synchronously and identically, defined as the second PWM duty cycle; the first PWM duty cycle and the second PWM duty cycle satisfy the following: The duty cycles of both the first and second PWM are greater than 0 and do not exceed 50%, and there is a difference between them.

[0033] In one specific numerical embodiment where there is a difference, when switching to the first filament, the first PWM duty cycle and the second PWM duty cycle are adjusted synchronously, and the adjusted first PWM duty cycle is in the range of 15% to 50%, and the adjusted second PWM duty cycle is in the range of 0.1% to 8%.

[0034] When switching to the second filament, the duty cycle of the first PWM and the duty cycle of the second PWM are adjusted synchronously, with the adjusted duty cycle of the second PWM in the range of 15% to 50% and the adjusted duty cycle of the first PWM in the range of 0.1% to 8%.

[0035] The working principle of the power control system in this embodiment of the invention is as follows: The input side of the PFC circuit is connected to an external AC power source, such as one output from a high-voltage generator. Figure 1 As shown, a stable DC bus voltage, such as 400V, can typically be formed across the filter capacitor C3. As mentioned above, the control channels of the second and third branches are decoupled from each other. The control channel of the second branch is as follows... Figure 2As shown, when the first controllable switch Q1 is turned on, the current path flowing through the first filament LF is from the upper plate of the first energy storage capacitor C1 through the first controllable switch Q1, the first filament LF, and then back to the lower plate of the first energy storage capacitor C1; when the second controllable switch Q2 is turned on, the current path flowing through the first filament LF is from the upper plate of the second energy storage capacitor C2 through the first filament LF, the second controllable switch Q2, and then back to the lower plate of the second energy storage capacitor C2.

[0036] The control channel of the third branch is as follows Figure 3 As shown, when the third controllable switch Q3 is turned on, the current path flowing through the second filament SF is from the upper plate of the first energy storage capacitor C1 through the third controllable switch Q3, the second filament SF, and then back to the lower plate of the first energy storage capacitor C1; when the fourth controllable switch Q4 is turned on, the current path flowing through the second filament SF is from the upper plate of the second energy storage capacitor C2 through the second filament SF, the fourth controllable switch Q4, and then back to the lower plate of the second energy storage capacitor C2.

[0037] The control channels of the second and third branches are decoupled from each other, meaning that when the first controllable switch Q1 is turned on, the third controllable switch Q3 or the fourth controllable switch Q4 can also be turned on. Therefore, the switching frequencies of the first controllable switch Q1 and the third / fourth controllable switches Q3 and Q4 can be different, thereby enabling the MOSFETs in the second and third branches to be adjusted to have different PWM duty cycles.

[0038] In one embodiment of the present invention, an X-ray tube is provided, including a cathode assembly, an anode target, and an internal vacuum housing. The cathode assembly includes a first filament and a second filament for emitting electrons. The X-ray tube also includes a power control system as described above.

[0039] In one embodiment of the present invention, an X-ray imaging system is provided, such as... Figure 4 As shown, the imaging system includes a high-voltage generator, a detector, an image processing unit, and an X-ray tube as described above. The high-voltage generator is configured to provide the X-ray tube with an anode high voltage and a filament driving power supply. The detector is configured to receive X-rays that pass through the subject and convert them into electrical signals. The image processing unit is configured to reconstruct an image based on the electrical signals.

[0040] like Figure 4 As shown, the X-ray imaging system also includes a filament switching control, which is configured to send a command to the X-ray tube to switch the filament. In response to the command to switch from the first filament to the second filament, the duty cycles of the first, second, third, and fourth controllable switches of the X-ray tube synchronous adjustment power control system are adjusted so that the duty cycles of the first and second controllable switches are greater than 0 and less than the duty cycles of the third and fourth controllable switches. In response to the command to switch from the second filament to the first filament, the duty cycles of the first, second, third, and fourth controllable switches of the X-ray tube synchronous adjustment power control system are adjusted so that the duty cycles of the third and fourth controllable switches are greater than 0 and less than the duty cycles of the first and second controllable switches.

[0041] In one embodiment of the present invention, such as Figure 5 As shown, an X-ray tube filament switching control method based on the power control system described above is provided, which switches the filament without shutting down the exposure through the following steps: The first filament of the X-ray tube is connected between the first connection node and the second connection node of the power control system, and the second filament of the X-ray tube is connected between the first connection node and the third connection node of the power control system. An external AC power source, such as that output from a high-voltage generator, is connected to the input terminal of the power control system so that the external AC power source forms a circuit with the inductor, freewheeling diode, and filter capacitor. In response to the command to switch from the first filament to the second filament, the duty cycles of the first controllable switch, the second controllable switch, the third controllable switch and the fourth controllable switch of the power control system are synchronously adjusted so that the duty cycles of the first controllable switch and the second controllable switch are greater than 0 and less than the duty cycles of the third controllable switch and the fourth controllable switch. In response to the command to switch from the second filament to the first filament, the duty cycles of the first, second, third, and fourth controllable switches of the power control system are synchronously adjusted so that the duty cycles of the third and fourth controllable switches are greater than 0 and less than the duty cycles of the first and second controllable switches.

[0042] The X-ray tube filament switching control method provided in this embodiment belongs to the same inventive concept as the power control system for X-ray tube filament switching provided in the above embodiment. Hereinafter, all contents of the power control system embodiment for X-ray tube filament switching are incorporated into this X-ray tube filament switching control method embodiment by reference, and will not be repeated.

[0043] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0044] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A power control system for switching X-ray tube filaments, characterized in that, The system is used to switch the first and second filaments of an X-ray tube under different focus modes without physically disconnecting either filament. The system includes a PFC circuit and a dual half-bridge topology circuit. The PFC circuit includes an inductor, a freewheeling diode, a filter capacitor, a PFC switch, and a PFC control chip. The inductor, freewheeling diode, and filter capacitor are connected in sequence. The PFC switch is located across the freewheeling diode and the filter capacitor. The PFC control chip is configured to control the duty cycle of the PFC switch so that the voltage across the filter capacitor is maintained at a preset value. The dual half-bridge topology circuit includes a first branch, a second branch, and a third branch connected in parallel with the filter capacitor. The first branch includes a first energy storage capacitor and a second energy storage capacitor connected in series. The second branch includes a first controllable switch and a second controllable switch connected in series. The third branch includes a third controllable switch and a fourth controllable switch connected in series. A first connection node is configured between the first energy storage capacitor and the second energy storage capacitor, which is configured to connect one end of the first filament and the second filament respectively; a second connection node is configured between the first controllable switch and the second controllable switch, which is configured to connect the other end of the first filament; a third connection node is configured between the third controllable switch and the fourth controllable switch, which is configured to connect the other end of the second filament.

2. The power control system for switching X-ray tube filaments according to claim 1, characterized in that, The duty cycles of the first controllable switch, the second controllable switch, the third controllable switch, and the fourth controllable switch are adjustable; The first controllable switch and the second controllable switch are turned on alternately, and the third controllable switch and the fourth controllable switch are turned on alternately.

3. The power control system for switching X-ray tube filaments according to claim 2, characterized in that, The control channels of the second branch and the third branch are decoupled from each other.

4. The power control system for switching X-ray tube filaments according to claim 2, characterized in that, The PWM duty cycles of the first controllable switch and the second controllable switch are adjusted synchronously and are consistent, and are defined as the first PWM duty cycle; The PWM duty cycles of the third and fourth controllable switches are synchronously adjusted and consistent, and are defined as the second PWM duty cycle. The duty cycle of the first PWM and the duty cycle of the second PWM are both greater than 0 and do not exceed 50%, and there is a difference between the two.

5. The power control system for switching X-ray tube filaments according to claim 4, characterized in that, When switching to the first filament, the duty cycle of the first PWM and the duty cycle of the second PWM are adjusted synchronously, and the adjusted duty cycle of the first PWM is greater than the duty cycle of the second PWM. When switching to the second filament, the duty cycle of the first PWM and the duty cycle of the second PWM are adjusted synchronously, and the adjusted duty cycle of the second PWM is greater than the duty cycle of the first PWM.

6. The power control system for switching X-ray tube filaments according to claim 4, characterized in that, When switching to the first filament, the duty cycle of the first PWM is adjusted within the range of 15% to 50%, and the duty cycle of the second PWM is adjusted simultaneously within the range of 0.1% to 8%. When switching to the second filament, the duty cycle of the second PWM is adjusted within the range of 15% to 50%, while the duty cycle of the first PWM is adjusted simultaneously within the range of 0.1% to 8%.

7. The power control system for switching X-ray tube filaments according to claim 1, characterized in that, The first energy storage capacitor and the second energy storage capacitor have the same capacitance value.

8. The power control system for switching X-ray tube filaments according to claim 7, characterized in that, The ratio of the capacitance of the filter capacitor to the capacitance of the first energy storage capacitor is between 10:1 and 500:

1.

9. The power control system for switching X-ray tube filaments according to claim 1, characterized in that, The negative terminal of the freewheeling diode is connected to the upper plate of the filter capacitor; The PFC switch is an NMOS transistor, with its drain connected to the positive terminal of the freewheeling diode and its source connected to the lower plate of the filter capacitor.

10. The power control system for switching X-ray tube filaments according to claim 1, characterized in that, The first controllable switch, the second controllable switch, the third controllable switch, and the fourth controllable switch are all NMOS transistors; The drains of the first and third controllable switches are both connected to the upper plate of the filter capacitor; the source of the first controllable switch is connected to the drain of the second controllable switch, and the source of the third controllable switch is connected to the drain of the fourth controllable switch; the sources of the second and fourth controllable switches are both connected to the lower plate of the filter capacitor.

11. An X-ray tube comprising a cathode assembly, an anode target, and an internal vacuum housing, said cathode assembly comprising a first filament and a second filament for emitting electrons, characterized in that, The X-ray tube further includes a power control system as described in any one of claims 1 to 9.

12. An X-ray imaging system, characterized in that, The device includes a high-voltage generator, a detector, an image processing unit, and an X-ray tube as claimed in claim 11, wherein the high-voltage generator is configured to provide an anode high voltage and a filament drive power supply to the X-ray tube, the detector is configured to receive X-rays passing through the subject and convert them into electrical signals, and the image processing unit is configured to reconstruct an image based on the electrical signals.

13. The X-ray imaging system according to claim 12, characterized in that, The system also includes a filament switching control configured to send a command to the X-ray tube to switch the filament. In response to the command to switch from the first filament to the second filament, the duty cycles of the first, second, third, and fourth controllable switches of the X-ray tube synchronous adjustment power control system are adjusted so that the duty cycles of the first and second controllable switches are greater than 0 and less than the duty cycles of the third and fourth controllable switches. In response to the command to switch from the second filament to the first filament, the duty cycles of the first, second, third, and fourth controllable switches of the X-ray tube synchronous adjustment power control system are adjusted so that the duty cycles of the third and fourth controllable switches are greater than 0 and less than the duty cycles of the first and second controllable switches.

14. A method for switching X-ray tube filaments based on a power control system as described in any one of claims 1 to 10, characterized in that, Switch the filament without turning off the exposure using the following steps: The first filament of the X-ray tube is connected between the first connection node and the second connection node of the power control system, and the second filament of the X-ray tube is connected between the first connection node and the third connection node of the power control system. An external AC power source is connected to the input terminal of the power control system so that the external AC power source forms a circuit with the inductor, freewheeling diode, and filter capacitor. In response to the command to switch from the first filament to the second filament, the duty cycles of the first controllable switch, the second controllable switch, the third controllable switch and the fourth controllable switch of the power control system are synchronously adjusted so that the duty cycles of the first controllable switch and the second controllable switch are greater than 0 and less than the duty cycles of the third controllable switch and the fourth controllable switch. In response to the command to switch from the second filament to the first filament, the duty cycles of the first, second, third, and fourth controllable switches of the power control system are synchronously adjusted so that the duty cycles of the third and fourth controllable switches are greater than 0 and less than the duty cycles of the first and second controllable switches.

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