A feedback control circuit for an X-ray tube and an X-ray source

Abstract

Embodiments of the present invention disclose a feedback control circuit for an X-ray tube and an X-ray source. The feedback control circuit includes: a current control circuit for implementing closed-loop feedback regulation of the X-ray tube's current; a voltage control circuit comprising a voltage control loop, an adder circuit, and a current feedback circuit, wherein the voltage control loop is configured to respond to changes in the X-ray tube's voltage to implement closed-loop feedback regulation of the X-ray tube's voltage; the current feedback circuit is configured to respond to changes in the X-ray tube's current and output a corresponding feedback signal; and the adder circuit is configured to superimpose the feedback signal on the closed-loop voltage feedback signal. Through the above-described approach, embodiments of the present invention can improve the X-ray source's ability to suppress busbar power-frequency ripple and reduce the voltage and current power-frequency ripple of the X-ray tube. Furthermore, embodiments of the present invention do not require additional busbar capacitance or high-voltage capacitance in the voltage sampling circuit, thereby reducing costs while improving system safety and reliability.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of X-ray sources, and in particular to a feedback control circuit of an X-ray tube and an X-ray source. Background Art

[0002] X-rays are widely used in security inspections, foreign body detection, ore sorting, industrial flaw detection, and medical equipment. The ripple in the output voltage and current of the X-ray source has a decisive impact on the quality and clarity of the image. If the ripple in the power frequency (typically 50Hz and 100Hz) of the output voltage and current is large, it will appear as a large water ripple in the image.

[0003] Currently, there are two general ways to reduce the power frequency ripple of X-ray tube voltage and X-ray tube current: one is to reduce the power frequency ripple output by the front-stage PFC circuit, for example, by increasing the bus capacitance, increasing the bus voltage or changing the modulation method of the input current; the other is to increase the voltage feedback loop bandwidth of the X-ray tube voltage.

[0004] The disadvantages of reducing the power frequency ripple of the X-ray tube voltage by reducing the power frequency ripple of the front-stage PFC circuit are as follows: increasing the bus capacitance will lead to increased cost, and at the same time, the input surge current is large when the power is first turned on; the increased amount of charge stored in the bus capacitance makes discharge difficult, resulting in reduced equipment and personal safety; increasing the bus voltage leads to increased capacitor voltage stress and reduced capacitor life, and the high price of high-voltage capacitors leads to increased cost; changing the input current modulation method leads to reduced AC input power factor and increased input current harmonics, resulting in serious waveform distortion.

[0005] Disadvantages of increasing the feedback loop bandwidth of the X-ray tube voltage and reducing the power frequency ripple of the X-ray tube voltage: The X-ray tube voltage of an X-ray source can reach tens to hundreds of kilovolts. The X-ray tube voltage sampling resistor is typically composed of multiple resistors of several hundred megohms connected in series, forming an upper voltage divider resistor with a resistance of up to a gigaohm or more. The lower voltage divider resistor is typically tens of kiloohms. In existing products, to increase the feedback loop bandwidth of the X-ray tube voltage, a high-voltage capacitor is connected in parallel with the upper voltage divider resistor. This is typically a series connection of multiple high-voltage capacitors with a voltage resistance of tens of kilovolts. These high-voltage capacitors are expensive, increasing costs. When the X-ray source is started and the X-ray tube voltage changes, the high-voltage capacitor acts as a differential element, causing large changes in the X-ray tube current, which can easily cause X-ray tube voltage oscillation and unstable source output. The high-voltage capacitor is composed of multiple capacitors connected in series, which creates a potential risk of sparks during assembly and welding, reducing the reliability of the source. Summary of the Invention

[0006] To solve the above technical problems, a technical solution adopted in an embodiment of the present invention is as follows: providing a feedback control circuit for an X-ray tube, comprising: a current control circuit, configured to: respond to changes in the current of the X-ray tube and output a corresponding current closed-loop feedback signal to achieve closed-loop feedback regulation of the current of the X-ray tube; a voltage control circuit, the voltage control circuit comprising: a voltage control loop, an adding circuit, a voltage modulation signal generating circuit, and a current feedback circuit, wherein the voltage control loop is configured to: respond to changes in the voltage of the X-ray tube and output a corresponding voltage closed-loop feedback signal to achieve closed-loop feedback regulation of the voltage of the X-ray tube; the current feedback circuit is configured to: respond to changes in the current of the X-ray tube and output a corresponding feedback signal; the adding circuit is configured to: superimpose the feedback signal on the voltage closed-loop feedback signal; the voltage modulation signal generating circuit is coupled to the output terminal of the adding circuit and is configured to: generate a corresponding voltage closed-loop feedback signal in response to changes in the output signal of the adding circuit.

[0007] In some embodiments, the current control circuit includes: a current sampling unit, configured to generate a first voltage signal that changes proportionally with the current of the X-ray tube; a current control unit, the current control unit including: a first reference voltage source, a first operational amplifier feedback circuit, and a current modulation signal generating circuit; wherein the non-inverting input and the inverting input of the first operational amplifier feedback circuit are coupled to the first reference voltage source and the current sampling unit, respectively; the current modulation signal generating circuit is coupled to the output of the first operational amplifier feedback circuit, and is configured to generate a corresponding current closed-loop feedback signal in response to changes in the output signal of the first operational amplifier feedback circuit.

[0008] In some embodiments, the voltage control loop includes: a voltage sampling unit, configured to generate a second voltage signal that changes proportionally with the voltage of the X-ray tube; a voltage control unit, the voltage control unit including: a second reference voltage source, an inverting amplifier circuit, and a second operational amplifier feedback circuit; wherein the non-inverting input and inverting input of the second operational amplifier feedback circuit are respectively coupled to the second reference voltage source and the inverting amplifier circuit; and the inverting amplifier circuit is used to output the sampled voltage to the inverting input of the second operational amplifier feedback circuit.

[0009] In some embodiments, the current feedback circuit includes a proportional-integral feedback circuit, which includes: a first resistor, a second resistor, a first capacitor and a first operational amplifier, wherein the inverting input terminal of the first operational amplifier is respectively connected to the first end of the first resistor and the first end of the second resistor, the non-inverting input terminal of the first operational amplifier is connected to the positive electrode of the first reference voltage source, and the output terminal of the first operational amplifier is connected to the adding circuit; the second end of the first resistor is connected to the current sampling unit, the second end of the second resistor is connected to the first end of the first capacitor, and the second end of the first capacitor is connected to the output terminal of the first operational amplifier.

[0010] In some embodiments, the current feedback circuit further includes a proportional-integral-differential closed-loop feedback circuit, which includes: an eighth resistor, a ninth resistor, a second capacitor, a third capacitor, and a second operational amplifier, wherein the inverting input terminal of the second operational amplifier is respectively connected to the first end of the eighth resistor, the first end of the ninth resistor, and the first end of the second capacitor, the non-inverting input terminal of the second operational amplifier is connected to the positive electrode of the first reference voltage source, and the output terminal of the second operational amplifier is connected to the adding circuit; the second end of the eighth resistor and the second end of the second capacitor are both connected to the current sampling unit, the second end of the ninth resistor is connected to the first end of the third capacitor, and the second end of the third capacitor is connected to the output terminal of the second operational amplifier; the output terminal of the second operational amplifier is connected to the input terminal of the current modulation signal generating circuit.

[0011] In some embodiments, the adding circuit includes a third resistor and a fourth resistor, wherein the first end of the third resistor is connected to the output end of the current feedback circuit, and the second end of the third resistor is respectively connected to the first end of the fourth resistor and the input end of the voltage modulation signal generating circuit; the second end of the fourth resistor is connected to the output end of the second op amp feedback circuit.

[0012] To solve the above technical problems, another technical solution adopted in an embodiment of the present invention is: to provide an X-ray source, characterized in that it includes: a power module, the power module is used to emit X-rays; and a feedback control module, the feedback control module is used to implement current closed-loop feedback regulation and voltage closed-loop feedback regulation of the power module.

[0013] In some embodiments, the power module includes a power factor correction circuit, an isolated boost circuit, a filament heating circuit and an X-ray tube, wherein the output end of the power factor correction circuit is respectively connected to the input end of the isolated boost circuit and the input end of the filament heating circuit; the output end of the isolated boost circuit is respectively connected to the current sampling circuit and the X-ray tube; and the output end of the filament heating circuit is connected to the cathode of the X-ray tube.

[0014] In some embodiments, the feedback control module includes a feedback control circuit of an X-ray tube as described above.

[0015] In some embodiments, the current sampling unit is a current sampling circuit, which is composed of a fifth resistor, wherein the first end of the fifth resistor is respectively connected to the output end of the isolation boost circuit and the inverting input end of the first operational amplifier feedback circuit, and the second end of the fifth resistor is respectively connected to the negative electrode of the first reference voltage source and the anode of the X-ray tube.

[0016] In some embodiments, the voltage sampling unit is a voltage sampling circuit, which includes a sixth resistor and a seventh resistor, wherein the first end of the sixth resistor is respectively connected to the anode of the X-ray tube and the negative electrode of the second reference voltage source, and the second end of the sixth resistor is respectively connected to the first end of the seventh resistor and the input end of the inverting amplifier circuit; the second end of the seventh resistor is connected to the cathode of the X-ray tube.

[0017] The beneficial effects of the embodiments of the present invention are as follows: unlike existing technologies, the embodiments of the present invention can improve the X-ray source's ability to suppress bus power-frequency ripple, reducing the voltage and current power-frequency ripple of the X-ray tube. Furthermore, the embodiments of the present invention do not require additional bus capacitance or high-voltage capacitance in the voltage sampling circuit, thereby reducing costs and improving system safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 is a schematic structural diagram of a feedback control circuit of an X-ray tube provided in an embodiment of the present invention;

[0019] Figure 2 1 is a schematic structural diagram of a current control circuit provided by an embodiment of the present invention;

[0020] Figure 3 1 is a schematic structural diagram of a voltage control circuit provided by an embodiment of the present invention;

[0021] Figure 4 1 is a hardware structure diagram of a proportional-integral feedback circuit provided in an embodiment of the present invention;

[0022] Figure 51 is a hardware structure diagram of a proportional-integral-differential closed-loop feedback circuit provided by an embodiment of the present invention;

[0023] Figure 6 1 is a schematic structural diagram of an adding circuit provided by an embodiment of the present invention;

[0024] Figure 7 1 is a schematic structural diagram of an X-ray source provided by an embodiment of the present invention;

[0025] Figure 8 1 is a schematic structural diagram of a power module provided by an embodiment of the present invention;

[0026] Figure 9 1 is a schematic structural diagram of a current sampling circuit provided by an embodiment of the present invention;

[0027] Figure 10 1 is a schematic structural diagram of a voltage sampling circuit provided by an embodiment of the present invention;

[0028] Figure 11 This is a hardware structure diagram of a monopole X-ray source provided in an embodiment of the present invention;

[0029] Figure 12 is a hardware structure diagram of a bipolar X-ray source provided by an embodiment of the present invention;

[0030] Figure 13 This is a hardware structure diagram of another bipolar X-ray source provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0032] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0033] See also Figure 1 , Figure 1 This is a structural schematic diagram of a feedback control circuit for an X-ray tube provided in an embodiment of the present invention. The feedback control circuit includes a current control circuit 100 and a voltage control circuit 200, wherein the voltage control circuit 200 includes a voltage control loop 210, an adding circuit 230, a current feedback circuit 220 and a voltage modulation signal generating circuit 240.

[0034] The output of the current control circuit 100 is connected to the input of the current feedback circuit 220 . The output of the current feedback circuit 220 is connected to the input of the adding circuit 230 . The adding circuit 230 is connected to the voltage control loop 210 . The adding circuit 230 is connected to the voltage modulation signal generating circuit 240 .

[0035] It should be noted that the current control circuit 100 is configured to respond to the current change of the X-ray tube and output a corresponding current closed-loop feedback signal to achieve closed-loop feedback regulation of the current of the X-ray tube.

[0036] The voltage control loop 210 is configured to respond to the voltage change of the X-ray tube and output a corresponding voltage closed-loop feedback signal to implement closed-loop feedback regulation of the voltage of the X-ray tube.

[0037] The current feedback circuit 220 is configured to respond to the current change of the X-ray tube and output a corresponding feedback signal.

[0038] The adding circuit 230 is configured to superimpose the feedback signal on the voltage closed-loop feedback signal.

[0039] The voltage modulation signal generating circuit 240 is configured to generate a corresponding voltage closed-loop feedback signal in response to a change in the output signal of the adding circuit 230 .

[0040] The structural diagram of the current control circuit 100 is shown in FIG. Figure 2 As shown, the current control circuit 100 includes a current sampling unit 110 and a current control unit 120 , wherein the current control unit 120 includes a first reference voltage source 121 , a first operational amplifier feedback circuit 122 and a current modulation signal generating circuit 123 .

[0041] The output of the current sampling unit 110 and the output of the first reference voltage source 121 are respectively connected to the inverting input and the non-inverting input of the first operational amplifier feedback circuit 122; the output of the first operational amplifier feedback circuit 122 is connected to the current modulation signal generating circuit.

[0042] It should be noted that the current sampling unit 110 is configured to generate a first voltage signal that changes in proportion to the current of the X-ray tube.

[0043] The current modulation signal generating circuit 123 is configured to generate a corresponding current closed-loop feedback signal in response to a change in the output signal of the first operational amplifier feedback circuit 122 .

[0044] The schematic diagram of the voltage control loop 210 is shown in FIG. Figure 3As shown, the voltage control loop 210 includes a voltage sampling unit 211 and a voltage control unit 212 , wherein the voltage control unit 212 includes a second reference voltage source 2121 , an inverting amplifier circuit 2122 and a second operational amplifier feedback circuit 2123 .

[0045] The output of the voltage sampling unit 211 is connected to the input of the inverting amplifier circuit 2122 . The output of the inverting amplifier circuit 2122 and the output of the second reference voltage source 2121 are connected to the inverting input and non-inverting input of the second operational amplifier feedback circuit 2123 , respectively.

[0046] It should be noted that the voltage sampling unit 211 is configured to generate a second voltage signal that changes following the voltage of the X-ray tube.

[0047] In a preferred embodiment, the current feedback circuit 220 includes a proportional-integral feedback circuit 221, such as Figure 4 As shown, the proportional-integral feedback circuit 221 includes a first resistor R1, a second resistor R2, a first capacitor C1 and a first operational amplifier U1.

[0048] Among them, the inverting input terminal of the first operational amplifier U1 is respectively connected to the first end of the first resistor R1 and the first end of the second resistor R2, the non-inverting input terminal of the first operational amplifier U1 is connected to the positive electrode of the first reference voltage source 121, and the output terminal of the first operational amplifier U1 is connected to the adding circuit 230.

[0049] The second end of the first resistor R1 is connected to the current sampling unit 110 , the second end of the second resistor R2 is connected to the first end of the first capacitor C1 , and the second end of the first capacitor C1 is connected to the output end of the first operational amplifier U1 .

[0050] In some other embodiments, the current feedback circuit 220 further includes a proportional-integral-differential closed-loop feedback circuit 222, such as Figure 5 As shown, the proportional-integral-differential closed-loop feedback circuit 222 includes an eighth resistor R8, a ninth resistor R9, a second capacitor C2, a third capacitor C3 and a second operational amplifier U2.

[0051] In which, the inverting input terminal of the second operational amplifier U2 is respectively connected to the first end of the eighth resistor R8, the first end of the ninth resistor R9 and the first end of the second capacitor C2, the non-inverting input terminal of the second operational amplifier U2 is connected to the positive electrode of the first reference voltage source 121, and the output terminal of the second operational amplifier U2 is connected to the adding circuit 230.

[0052] The second end of the eighth resistor R8 and the second end of the second capacitor C2 are both connected to the current sampling unit 110, the second end of the ninth resistor R9 is connected to the first end of the third capacitor C3, and the second end of the third capacitor C3 is connected to the output end of the second operational amplifier U2.

[0053] The output terminal of the second operational amplifier U2 is connected to the input terminal of the adding circuit 230 .

[0054] It should be noted that the above-mentioned proportional-integral feedback circuit 221 and the proportional-integral-differential closed-loop feedback circuit 222 are used to illustrate the function of the current feedback circuit 220. For ordinary technicians in this field, without departing from the concept of the present invention, several variations and improvements can be made to realize the function of the current feedback circuit 220, and these all fall within the scope of protection of the present invention.

[0055] In a preferred embodiment, the hardware structure of the adding circuit 230 is shown in FIG. Figure 6 As shown, the adding circuit 230 includes a third resistor R3 and a fourth resistor R4, wherein the first end of the third resistor R3 is connected to the output end of the current feedback circuit 220, and the second end of the third resistor R3 is respectively connected to the first end of the fourth resistor R4 and the input end of the voltage modulation signal generating circuit 240; the second end of the fourth resistor R4 is connected to the output end of the second operational amplifier feedback circuit 2123.

[0056] It should be noted that, under the premise of using a digitally controlled X-ray source, the closed-loop feedback control of the X-ray tube voltage and the closed-loop feedback control of the X-ray tube current can be implemented through mathematical and logical operations, and the adder circuit U5 is also implemented by mathematical operations. The X-ray tube feedback control circuit implemented in this manner is also within the scope of protection of this application.

[0057] See also Figure 7 , Figure 7 This is a schematic diagram of the structure of an X-ray source provided in an embodiment of the present invention. The X-ray source includes a power module 30 and a feedback control module 20. The power module 30 is used to emit X-rays, and the feedback control module 20 is used to implement closed-loop current feedback control and closed-loop voltage feedback control of the power module 30. The power module 30 and the feedback control module 20 are interconnected.

[0058] It should be noted that the feedback control module 20 includes the following Figure 1 A feedback control circuit of an X-ray tube is shown.

[0059] In some embodiments, the power module 30 is as follows Figure 8 As shown, Figure 8 The power module 30 shown includes a power factor correction circuit 310 , an isolated boost circuit 320 , a filament heating circuit 330 , and an X-ray tube 340 .

[0060] Among them, the output end of the power factor correction circuit 310 is respectively connected to the input end of the isolation boost circuit 320 and the input end of the filament heating circuit 330, the output end of the filament heating circuit 330 is connected to the cathode of the X-ray tube 340, and the output end of the isolation boost circuit 320 is respectively connected to the anode and cathode of the X-ray tube 340.

[0061] In some embodiments, the current sampling unit 100 is a current sampling circuit, such as Figure 9 As shown, the current sampling circuit 100 includes a fifth resistor R5, a first end of the fifth resistor R5 is respectively connected to the output end of the isolation boost circuit 310 and the inverting input end of the first operational amplifier feedback circuit 122, a second end of the fifth resistor R5 is respectively connected to the negative electrode of the first reference voltage source 121 and the anode of the X-ray tube 340, and a second end of the fifth resistor R5 is grounded.

[0062] In some embodiments, the voltage sampling unit 211 is a voltage sampling circuit, such as Figure 10 As shown, the voltage sampling circuit 211 includes a sixth resistor R6 and a seventh resistor R7, the first end of the sixth resistor R6 is respectively connected to the anode of the X-ray tube 340 and the negative electrode of the second reference voltage source 2121, the second end of the sixth resistor R6 is respectively connected to the first end of the seventh resistor R7 and the input end of the inverting amplifier circuit 2122; the second end of the seventh resistor R7 is connected to the cathode of the X-ray tube 340.

[0063] It should be noted that the above-mentioned proportional current sampling circuit 100 and voltage sampling circuit 211 are used to illustrate the functions of the current sampling unit 100 and the voltage sampling unit 211, respectively. Those skilled in the art will appreciate that, without departing from the scope of the present invention, various modifications and improvements may be made to implement the functions of the current sampling unit 100 and the voltage sampling unit 211, and all such modifications and improvements fall within the scope of protection of the present invention.

[0064] In a preferred embodiment, the hardware structure of the monopole X-ray source is as follows: Figure 11 As shown, the power factor correction circuit 310, the isolation boost circuit 320, the filament heating circuit 330, and the X-ray tube 340 (including the filament) constitute the power module of the X-ray source.

[0065] The fifth resistor R5 constitutes a current sampling unit of the X-ray source.

[0066] The sixth resistor R6 and the seventh resistor R7 constitute a voltage sampling unit of the X-ray source. The first end of the sixth resistor R6 is respectively connected to the anode of the X-ray tube 340 and the negative electrode of the second reference voltage source 2121, and the second end of the sixth resistor R6 is respectively connected to the first end of the seventh resistor R7 and the input end of the inverting amplifier circuit 2122; the second end of the seventh resistor R7 is connected to the cathode of the X-ray tube 340.

[0067] The first reference voltage source 121 , the first operational amplifier feedback circuit 122 , and the current modulation signal generating circuit 123 constitute a current control unit of the X-ray source.

[0068] The second reference voltage source 2121 , the inverting amplifier circuit 2122 and the second operational amplifier feedback circuit 2123 constitute a voltage control unit of the X-ray source.

[0069] The current of the X-ray tube 340 forms a current sampling signal Is after passing through the fifth resistor R5. The first end of the fifth resistor R5 is connected to the inverting input terminal of the first operational amplifier feedback circuit 122 and the inverting input terminal of the current feedback circuit 220. The second end of the fifth resistor R5 is connected to the negative electrode of the first reference voltage source 121 and the anode of the X-ray tube 340, respectively. The second end of the fifth resistor R5 is grounded. The positive electrode of the first reference voltage source 121 is connected to the non-inverting input terminal of the first operational amplifier feedback circuit 122 and the non-inverting input terminal of the current feedback circuit 220, respectively.

[0070] The first operational amplifier feedback circuit 122 outputs the output signal I ea to the current modulation signal generating circuit 123. The current modulation signal generating circuit 123 outputs a voltage closed-loop feedback signal PWM1, which is connected to the filament heating circuit 330 to control the voltage of the filament in the X-ray tube 340 and ultimately control the current of the X-ray tube 340.

[0071] The current feedback circuit 220 outputs the output signal I ea1 to an input terminal of the adding circuit 230. It should be noted that in actual design, due to different bandwidth requirements between the current feedback circuit 220 and the first operational amplifier feedback circuit 122, the bandwidth of the current feedback circuit 220 is much higher than the bandwidth of the first operational amplifier feedback circuit 122. Therefore, the two cannot use the same operational amplifier feedback circuit.

[0072] The sixth resistor R6 and the seventh resistor R7 sample the voltage of the X-ray tube 340, and the sampled signal is transmitted to the inverting amplifier circuit 2122. The inverting amplifier circuit 2122 performs inverting amplification on the negative voltage signal to generate a positive voltage sampling signal and outputs the output signal Vea to the inverting input terminal of the second operational amplifier feedback circuit 2123. The positive electrode of the second reference voltage source 2121 is connected to the non-inverting input terminal of the second operational amplifier feedback circuit 2123. The second operational amplifier feedback circuit 2123 outputs the output signal Vea to the other input terminal of the adding circuit 230. The adding circuit 230 adds Vea and Iea1. The adding circuit 230 outputs the output signal Vea1 to the voltage modulation signal generating circuit 240. The voltage modulation signal generating circuit 240 generates a voltage modulation signal PWM2 and outputs it to the isolated boost circuit 320 to control the voltage between the anode and cathode of the X-ray tube 340, thereby realizing closed-loop feedback control of the voltage of the X-ray tube 340.

[0073] In this embodiment, the current feedback circuit 220 is as follows: Figure 4 As shown, the adding circuit 230 is as shown in FIG. Figure 6 As shown, the current sampling signal Is of the X-ray tube 340 is connected to the first end of the first resistor R1, the other end of the first resistor R1 and the first end of the second resistor R2 are commonly connected to the inverting input end of the first operational amplifier U1, and the other end of the second resistor R2 is connected to the first end of the first capacitor C1 to form a feedback branch.

[0074] The other end of the first capacitor C1 and the first end of the third resistor R3 are commonly connected to the output of the first operational amplifier U1. The non-inverting input of the first operational amplifier U1 is connected to the first reference voltage source 121. The first resistor R1, the second resistor R2, the first capacitor C1, and the first operational amplifier U1 collectively form a current feedback circuit 220. The third resistor R3 and the fourth resistor R4 form a simple adding circuit 230, wherein the first end of the third resistor R3 is connected to the output of the current feedback circuit 220, and the other end is connected to the first end of the fourth resistor R4 to form the output signal of the adding circuit 230. The other end of the fourth resistor R4 is connected to the output signal Vea of the second operational amplifier feedback circuit 2123. Therefore, the following is true:

[0075]

[0076] It should be noted that, in addition to Figure 11 In addition to the unipolar X-ray tubes shown, there are also bipolar X-ray tubes, see Figure 12 In a preferred embodiment, the power factor correction circuit 310, the isolation boost circuit 320, the filament heating circuit 330, and the X-ray tube 340 (including the filament) constitute a power module of the X-ray source.

[0077] The fifth resistor R5 constitutes a current sampling unit of the X-ray source.

[0078] The sixth resistor R6 and the seventh resistor R7 form a voltage sampling unit of the X-ray source. The first end of the sixth resistor R6 is respectively connected to the negative electrode of the first reference voltage source 121 and the negative electrode of the second reference voltage source 2121, and the second end of the sixth resistor R6 is respectively connected to the first end of the seventh resistor R7 and the input end of the inverting amplifier circuit 2122; the second end of the seventh resistor R7 is connected to the cathode of the X-ray tube 340.

[0079] The first reference voltage source 121, the first operational amplifier feedback circuit 122, and the current modulation signal generating circuit 123 constitute a current control unit of the X-ray source;

[0080] The second reference voltage source 2121 , the inverting amplifier circuit 2122 and the second operational amplifier feedback circuit 2123 constitute a voltage control unit of the X-ray source.

[0081] The isolation boost circuit outputs the current sampling signal Is to the first end of the fifth resistor R5. The first end of the fifth resistor R5 is respectively connected to the inverting input end of the first operational amplifier feedback circuit 122 and the inverting input end of the proportional-integral feedback circuit 221 included in the current feedback circuit 220. The second end of the fifth resistor R5 is grounded. The positive electrode of the first reference voltage source 121 is respectively connected to the non-inverting input end of the first operational amplifier feedback circuit 122 and the non-inverting input end of the proportional-integral feedback circuit 221 included in the current feedback circuit 220.

[0082] The first operational amplifier feedback circuit 122 outputs the output signal I ea to the current modulation signal generating circuit 123. The current modulation signal generating circuit 123 outputs a voltage closed-loop feedback signal PWM1, which is connected to the filament heating circuit 330 to control the voltage of the filament in the X-ray tube 340 and ultimately control the current of the X-ray tube 340.

[0083] The current feedback circuit 220 includes a proportional-integral feedback circuit 221 that outputs an output signal I ea1 to an input terminal of the adding circuit 230. It should be noted that in actual design, due to different bandwidth requirements between the current feedback circuit 220 and the first operational amplifier feedback circuit 122, the bandwidth of the current feedback circuit 220 is much higher than the bandwidth of the first operational amplifier feedback circuit 122. Therefore, the two cannot use the same operational amplifier feedback circuit.

[0084] The sixth resistor R6 and the seventh resistor R7 sample the voltage of the X-ray tube 340, and the sampled signal is transmitted to the inverting amplifier circuit 2122. The inverting amplifier circuit 2122 performs inverting amplification on the negative voltage signal to generate a positive voltage sampling signal and outputs the output signal Vea to the inverting input terminal of the second operational amplifier feedback circuit 2123. The positive electrode of the second reference voltage source 2121 is connected to the non-inverting input terminal of the second operational amplifier feedback circuit 2123. The second operational amplifier feedback circuit 2123 outputs the output signal Vea to the other input terminal of the adding circuit 230. The adding circuit 230 adds Vea and Iea1. The adding circuit 230 outputs the output signal Vea1 to the voltage modulation signal generating circuit 240. The voltage modulation signal generating circuit 240 generates a voltage modulation signal PWM2 and outputs it to the isolated boost circuit 320 to control the voltage between the anode and cathode of the X-ray tube 340, thereby realizing closed-loop feedback control of the voltage of the X-ray tube 340.

[0085] In this embodiment, the current feedback circuit 220 includes a proportional-integral feedback circuit 221 as shown in FIG. Figure 4 As shown, the adding circuit 230 is as shown in FIG. Figure 6 As shown, the current sampling signal Is of the X-ray tube 340 is connected to the first end of the first resistor R1, the other end of the first resistor R1 and the first end of the second resistor R2 are commonly connected to the inverting input end of the first operational amplifier U1, and the other end of the second resistor R2 is connected to the first end of the first capacitor C1 to form a feedback branch.

[0086] The other end of the first capacitor C1 and the first end of the third resistor R3 are commonly connected to the output of the first operational amplifier U1. The non-inverting input of the first operational amplifier U1 is connected to the first reference voltage source 121. The first resistor R1, the second resistor R2, the first capacitor C1, and the first operational amplifier U1 collectively form a current feedback circuit 220. The third resistor R3 and the fourth resistor R4 form a simple adding circuit 230, wherein the first end of the third resistor R3 is connected to the output of the current feedback circuit 220, and the other end is connected to the first end of the fourth resistor R4 to form the output signal of the adding circuit 230. The other end of the fourth resistor R4 is connected to the output signal Vea of the second operational amplifier feedback circuit 2123. Therefore, the following is true:

[0087]

[0088] It should be noted that Figure 12 The voltage sampling unit 340 in the bipolar X-ray tube shown in FIG. 1 only takes the voltage on one side of the X-ray tube, or can take the voltage on both sides of the isolated boost circuit 320, as shown in FIG. Figure 13 shown.

[0089] In a preferred embodiment, the power factor correction circuit 310, the isolated boost circuit 320, the filament heating circuit 330, and the X-ray tube 340 (including the filament) constitute a power module of the X-ray source.

[0090] The fifth resistor R5 constitutes a current sampling unit of the X-ray source.

[0091] The sixth resistor R6 and the eighth resistor R8 form a voltage sampling unit for the anode of the X-ray tube 340 , and the seventh resistor R7 and the ninth resistor R9 form a voltage sampling unit for the cathode of the X-ray tube 340 .

[0092] In this embodiment, the inverting amplifier circuit 2122 needs to be replaced by a differential amplifier circuit;

[0093] The first end of the eighth resistor R8 is connected to the anode of the X-ray tube 340, the second end of the eighth resistor R8 is respectively connected to the first end of the sixth resistor R6 and the input end of the differential amplifier circuit 2124, and the second end of the sixth resistor R6 is connected to the first end of the seventh resistor R7.

[0094] A first end of the ninth resistor R9 is connected to the cathode of the X-ray tube 340 , and a second end of the ninth resistor R9 is connected to the second end of the seventh resistor R7 and the input end of the differential amplifier circuit 2124 .

[0095] The first reference voltage source 121 , the first operational amplifier feedback circuit 122 , and the current modulation signal generating circuit 123 constitute a current control unit of the X-ray source.

[0096] The second reference voltage source 2121 , the second operational amplifier feedback circuit 2123 and the differential amplifier circuit 2124 constitute a voltage control unit of the X-ray source.

[0097] The isolation boost circuit outputs the current sampling signal Is to the first end of the fifth resistor R5. The first end of the fifth resistor R5 is connected to the inverting input terminal of the first operational amplifier feedback circuit 122 and the inverting input terminal of the current feedback circuit 220, respectively. The second end of the fifth resistor R5 is grounded. The positive electrode of the first reference voltage source 121 is connected to the non-inverting input terminal of the first operational amplifier feedback circuit 122 and the non-inverting input terminal of the current feedback circuit 220, respectively. The negative electrode of the first reference voltage source 121 is grounded.

[0098] The first operational amplifier feedback circuit 122 outputs the output signal I ea to the current modulation signal generating circuit 123. The current modulation signal generating circuit 123 outputs a voltage closed-loop feedback signal PWM1, which is connected to the filament heating circuit 330 to control the voltage of the filament in the X-ray tube 340 and ultimately control the current of the X-ray tube 340.

[0099] The current feedback circuit 220 outputs the output signal I ea1 to an input terminal of the adding circuit 230. It should be noted that in actual design, due to different bandwidth requirements between the current feedback circuit 220 and the first operational amplifier feedback circuit 122, the bandwidth of the current feedback circuit 220 is much higher than the bandwidth of the first operational amplifier feedback circuit 122. Therefore, the two cannot use the same operational amplifier feedback circuit.

[0100] The sixth resistor R6 and the eighth resistor R8 of the voltage sampling unit of the anode of the X-ray tube 340, and the seventh resistor R7 and the ninth resistor R9 of the voltage sampling unit of the cathode of the X-ray tube 340 sample the voltage of the X-ray tube 340 to obtain a sampling signal. The sampling signal is transmitted to the differential amplifier circuit 2124. The differential amplifier circuit 2124 performs differential amplification on the voltage samples of the anode and cathode of the X-ray tube 340 to generate a positive polarity voltage sampling signal, and outputs the output signal Vea to the inverting input terminal of the second operational amplifier feedback circuit 2123. The positive electrode of the second reference voltage source 2121 is connected to the non-inverting input terminal of the second operational amplifier feedback circuit 2123, and the negative electrode of the second reference voltage source 2121 is grounded. The second operational amplifier feedback circuit 2123 outputs the output signal Vea to the other input terminal of the adding circuit 230. The adding circuit 230 performs a summation on Vea and I ea1 is added, and the adding circuit 230 outputs the output signal Vea1 to the voltage modulation signal generating circuit 240. The voltage modulation signal generating circuit 240 generates a voltage modulation signal PWM2, which is output to the isolated boost circuit 320 to control the voltage between the anode and cathode of the X-ray tube 340, thereby realizing closed-loop feedback control of the voltage of the X-ray tube 340.

[0101] In this embodiment, the current feedback circuit 220 is as follows: Figure 4 As shown, the adding circuit 230 is as shown in FIG. Figure 6 As shown, the current sampling signal Is of the X-ray tube 340 is connected to the first end of the first resistor R1, the other end of the first resistor R1 and the first end of the second resistor R2 are commonly connected to the inverting input end of the first operational amplifier U1, and the other end of the second resistor R2 is connected to the first end of the first capacitor C1 to form a feedback branch.

[0102] The other end of the first capacitor C1 and the first end of the third resistor R3 are commonly connected to the output of the first operational amplifier U1. The non-inverting input of the first operational amplifier U1 is connected to the first reference voltage source 121. The first resistor R1, the second resistor R2, the first capacitor C1, and the first operational amplifier U1 collectively form a current feedback circuit 220. The third resistor R3 and the fourth resistor R4 form a simple adding circuit 230, wherein the first end of the third resistor R3 is connected to the output of the current feedback circuit 220, and the other end is connected to the first end of the fourth resistor R4 to form the output signal of the adding circuit 230. The other end of the fourth resistor R4 is connected to the output signal Vea of the second operational amplifier feedback circuit 2123. Therefore, the following is true:

[0103]

[0104] Different from the existing technology, the above method adds a fast-response current feedback circuit and an adding circuit to the voltage closed-loop feedback circuit and current closed-loop feedback circuit of the existing X-ray source. The output signal of the current feedback circuit is added to the voltage closed-loop feedback signal, and the sum signal is used to control the X-ray tube voltage, thereby improving the bandwidth of the X-ray tube voltage closed-loop feedback circuit and reducing the output power frequency ripple of the X-ray tube voltage.

[0105] The above description is only an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A feedback control circuit for an X-ray tube, characterized in that: include: The current control circuit is configured to: respond to the current change of the X-ray tube and output a corresponding current closed-loop feedback signal to achieve closed-loop feedback regulation of the current of the X-ray tube; A voltage control circuit, comprising: a voltage control loop, an adding circuit, a voltage modulation signal generating circuit and a current feedback circuit, wherein: The voltage control loop is configured to: respond to a voltage change of the X-ray tube and output a corresponding voltage closed-loop feedback signal to implement voltage closed-loop feedback regulation of the X-ray tube; The current feedback circuit is configured to: respond to a current change of the X-ray tube and output a corresponding feedback signal; The adding circuit is configured to: superimpose the feedback signal on the voltage closed-loop feedback signal; The voltage modulation signal generating circuit is coupled to the output terminal of the adding circuit, and is configured to generate a corresponding voltage closed-loop feedback signal in response to a change in the output signal of the adding circuit.

2. The control circuit according to claim 1, wherein: The current control circuit comprises: a current sampling unit configured to: generate a first voltage signal that varies in proportion to the current of the X-ray tube; A current control unit, comprising: a first reference voltage source, a first operational amplifier feedback circuit, and a current modulation signal generating circuit; Wherein, the non-inverting input terminal and the inverting input terminal of the first operational amplifier feedback circuit are coupled to the first reference voltage source and the current sampling unit respectively; The current modulation signal generating circuit is coupled to the output terminal of the first operational amplifier feedback circuit, and is configured to generate a corresponding current closed-loop feedback signal in response to a change in the output signal of the first operational amplifier feedback circuit.

3. The control circuit according to claim 2, characterized in that: The voltage control loop includes: a voltage sampling unit configured to: generate a second voltage signal that varies in proportion to the voltage of the X-ray tube; A voltage control unit, comprising: a second reference voltage source, an inverting amplifier circuit, and a second operational amplifier feedback circuit; Wherein, the non-inverting input terminal and the inverting input terminal of the second operational amplifier feedback circuit are coupled to the second reference voltage source and the inverting amplifier circuit respectively; The inverting amplifier circuit is used to output the sampling voltage to the inverting input terminal of the second operational amplifier feedback circuit.

4. The control circuit according to claim 2, characterized in that: The current feedback circuit includes a proportional-integral feedback circuit, which includes: a first resistor, a second resistor, a first capacitor, and a first operational amplifier, wherein: The inverting input terminal of the first operational amplifier is connected to the first end of the first resistor and the first end of the second resistor respectively, the non-inverting input terminal of the first operational amplifier is connected to the positive electrode of the first reference voltage source, and the output terminal of the first operational amplifier is connected to the adding circuit; The second end of the first resistor is connected to the current sampling unit, the second end of the second resistor is connected to the first end of the first capacitor, and the second end of the first capacitor is connected to the output end of the first operational amplifier.

5. The control circuit according to claim 1, wherein: The current feedback circuit further includes a proportional-integral-differential closed-loop feedback circuit, which includes: an eighth resistor, a ninth resistor, a second capacitor, a third capacitor, and a second operational amplifier, wherein: an inverting input terminal of the second operational amplifier connected to the first terminal of the eighth resistor, the first terminal of the ninth resistor, and the first terminal of the second capacitor, respectively; a non-inverting input terminal of the second operational amplifier connected to the positive electrode of the first reference voltage source; and an output terminal of the second operational amplifier connected to the adding circuit; The second end of the eighth resistor and the second end of the second capacitor are both connected to the current sampling unit, the second end of the ninth resistor is connected to the first end of the third capacitor, and the second end of the third capacitor is connected to the output end of the second operational amplifier; The output terminal of the second operational amplifier is connected to the input terminal of the current modulation signal generating circuit.

6. The control circuit according to claim 1, wherein: The adding circuit includes a third resistor and a fourth resistor, wherein: The first end of the third resistor is connected to the output end of the current feedback circuit, and the second end of the third resistor is connected to the first end of the fourth resistor and the input end of the voltage modulation signal generating circuit respectively; The second end of the fourth resistor is connected to the output end of the second operational amplifier feedback circuit.

7. An X-ray source, characterized in that: include: A power module, wherein the power module is used to emit X-rays; A feedback control module comprising a feedback control circuit of an X-ray tube according to any one of claims 1 to 6, wherein the feedback control module is used to implement current closed-loop feedback regulation and voltage closed-loop feedback regulation of the power module.

8. The X-ray source according to claim 7, characterized in that The power module includes a power factor correction circuit, an isolation boost circuit, a filament heating circuit and an X-ray tube. Wherein, the output end of the power factor correction circuit is connected to the input end of the isolation boost circuit and the input end of the filament heating circuit respectively; The output end of the isolation boost circuit is connected to the current sampling circuit and the X-ray tube respectively; The output end of the filament heating circuit is connected to the cathode of the X-ray tube.

9. The X-ray source according to claim 7, characterized in that The current sampling unit is a current sampling circuit, which is composed of a fifth resistor. The first end of the fifth resistor is respectively connected to the output end of the isolation boost circuit and the inverting input end of the first operational amplifier feedback circuit, and the second end of the fifth resistor is respectively connected to the negative electrode of the first reference voltage source and the anode of the X-ray tube.

10. The X-ray source according to claim 7, characterized in that The voltage sampling unit is a voltage sampling circuit, which includes a sixth resistor and a seventh resistor, wherein a first end of the sixth resistor is connected to an anode of the X-ray tube and a negative electrode of the second reference voltage source, respectively, and a second end of the sixth resistor is connected to a first end of the seventh resistor and an input end of the inverting amplifier circuit, respectively; A second end of the seventh resistor is connected to a cathode of the X-ray tube.

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