CN113079616A - X-ray tube filament driving circuit - Google Patents
X-ray tube filament driving circuit Download PDFInfo
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- CN113079616A CN113079616A CN202010003726.6A CN202010003726A CN113079616A CN 113079616 A CN113079616 A CN 113079616A CN 202010003726 A CN202010003726 A CN 202010003726A CN 113079616 A CN113079616 A CN 113079616A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05G—X-RAY TECHNIQUE
- H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
- H05G1/08—Electrical details
- H05G1/10—Power supply arrangements for feeding the X-ray tube
- H05G1/12—Power supply arrangements for feeding the X-ray tube with dc or rectified single-phase ac or double-phase
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05G—X-RAY TECHNIQUE
- H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
- H05G1/08—Electrical details
- H05G1/26—Measuring, controlling or protecting
- H05G1/265—Measurements of current, voltage or power
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05G—X-RAY TECHNIQUE
- H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
- H05G1/08—Electrical details
- H05G1/26—Measuring, controlling or protecting
- H05G1/30—Controlling
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- X-Ray Techniques (AREA)
Abstract
The invention discloses an X-ray tube filament driving circuit which is used for driving a filament with a cathode connected with high voltage, low voltage or grounding, and the filament driving circuit specifically comprises a control unit, a power supply unit, a filament isolation transformer, a high-frequency rectification filter unit and an isolation sampler. The filament driving circuit is a direct current constant current driving circuit with the cathode filament connected with high voltage, low voltage or grounded, and has the advantages of convenient access, stable constant current and small ripple.
Description
Technical Field
The invention belongs to X-ray equipment with an X-ray tube, and particularly relates to a filament driving circuit of the X-ray tube.
Background
The X-ray is discovered by the German physicist Lonqin 11.8.1895, and the great discovery of the X-ray is of great significance to the recent scientific theory or the applied technology, especially to the continuous innovation and breakthrough in the medical science field.
The basic structure of the X-ray tube includes an X-ray tube, a transformer, and a control unit, although the types of the X-ray tube are different. The X-ray tube is a hot cathode vacuum tube, mostly a vacuum two-stage tube structure, and also a three-stage tube structure in special applications. In an X-ray tube used in general medical field, a cathode is a tungsten filament, an anode is a tungsten target, a low-voltage current passes through the filament, the filament generates heat to generate an electron group, the tungsten target of the anode is used for blocking a fast-running electron group, and a high voltage is applied to two poles of the X-ray tube, so that the electron group moves from the cathode to the anode at a high speed, and the electron group is suddenly blocked by impacting the tungsten target to generate X-rays and a large amount of heat energy. In an X-ray machine, a high voltage transformer supplies high voltage to both poles of an X-ray tube, and a step-down transformer, i.e., a filament transformer, supplies low voltage to a cathode filament. When the X-ray machine is used, a control unit is needed to adjust various required technical conditions, and the control unit is mainly used for adjusting the voltage of two poles of the X-ray tube and the current passing through a cathode filament. The current passing through the cathode filament is also called the filament heating current, and the voltage applied to the two ends of the cathode filament of the X-ray tube is called the filament heating voltage.
The common X-ray tube filament driving circuit adopts a high-frequency alternating current pulse mode to heat the filament, has the advantage of convenient access, and has more obvious advantages when a cathode is connected with high voltage. However, compared with a direct current constant current driving mode, the current fluctuation amplitude of a high-frequency alternating current pulse mode is large, and the tube current ripple of the X-ray tube is large, so that the final imaging quality is influenced. When the cathode of the X-ray tube is not high in voltage or the cathode is grounded, the direct current constant current driving mode well makes up the defect of large fluctuation amplitude of the high-frequency alternating current pulse mode. However, the conventional dc constant current driving method cannot work normally when the cathode is connected to a high voltage.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art described above.
Therefore, the invention aims to provide a filament direct current constant current driving circuit with an X-ray tube cathode connected with high voltage, low voltage or ground, and the circuit has the advantages of convenience in connection, stable constant current and small ripple.
In order to achieve the above object, an embodiment of the present invention discloses an X-ray tube filament driving circuit for driving a filament with a cathode connected to a high voltage, a low voltage or a ground, including: the control unit is connected with the power supply unit and used for controlling the power supply unit to output a first filament heating voltage; the filament isolation transformer is connected with the power supply unit and is used for converting the received first filament heating voltage into a second filament heating voltage; the high-frequency rectifying and filtering unit is connected with the filament isolation transformer and is used for converting the received second filament heating voltage into direct-current filament heating voltage and outputting the direct-current filament heating voltage to the filament; one end of the isolation sampler is connected with the high-frequency rectifying and filtering unit, and the other end of the isolation sampler is connected with the control unit and used for collecting filament current and feeding back a current sampling signal to the control unit; when the cathode is connected with high voltage or low voltage, the high voltage or low voltage superposed on the filament is transmitted to the filament isolation transformer and the isolation sampler through the high-frequency rectification filter unit and is isolated by the filament isolation transformer and the isolation sampler.
Preferably, the power supply unit further includes a power frequency rectifying and filtering module and a high frequency inverting module, the power frequency rectifying and filtering module receives the mains supply and converts the mains supply into a first voltage, and transmits the first voltage to the high frequency inverting module connected to the power frequency rectifying and filtering module, and the high frequency inverting module is connected to the control unit and receives the first voltage and converts the first voltage into a first filament heating voltage.
Preferably, the control unit further includes a closed-loop control module, a PWM control module, and a driving module, wherein one end of the closed-loop control module is connected to the isolation sampler, the closed-loop control module outputs a control level signal according to a current sampling signal output by the isolation sampler, the other end of the closed-loop control module is connected to the PWM control module, the PWM control module outputs a PWM signal according to the control level signal, one end of the driving module is connected to the PWM control module, the other end of the driving module is connected to the high-frequency inverter module, and outputs a driving signal according to the PWM signal to drive the high-frequency inverter module.
Preferably, the method comprises the following steps: the filament isolation transformer, the high-frequency rectification filter unit, the isolation sampler and the X-ray tube comprising the filament are arranged in the insulating oil tank in an insulating way.
Preferably, the filament isolation transformer includes the magnetic core, the magnetic core includes two mutual symmetrical half magnetic cores, half magnetic core include transverse connection portion and certainly the coiling portion that one side extended the formation in the both ends of transverse connection portion, two the tip counterbalance of the coiling portion of half magnetic core leans on to form the magnetic core, magnetic core one side coiling portion cover establishes elementary solenoid, the magnetic core opposite side coiling portion cover establishes insulating skeleton, set up secondary coil on insulating skeleton's the section of thick bamboo portion, insulating skeleton still includes the extension of outside extension from section of thick bamboo portion both ends.
Preferably, the insulating skeleton is made of polyimide, wherein the thickness of the cylindrical portion is not less than 3 mm.
Preferably, the extension distance and the thickness of the extension part are both less than 3 mm.
Preferably, the outer layer of the secondary coil is coated with an insulating layer, and the insulating layer is made of silicon rubber with withstand voltage of not less than 10 KV.
Preferably, keep apart the sample thief and include hall sensor, have a section of thick bamboo of keeping apart of a section of thick bamboo connecting portion and locking portion, a section of thick bamboo connecting portion have along the section of thick bamboo that left right direction extends and stretch, the one end of a section of thick bamboo connecting portion is passed hall sensor and is fixed with locking portion cooperation, the section of thick bamboo is stretched and is had the section of thick bamboo that extends along left right direction and stretch the through-hole in stretching, a section of thick bamboo stretch the through-hole and be used for the wire that awaits measuring to pass to.
Preferably, the other end of the barrel link has a flange extending radially outwardly from the end portion along the barrel, and the thickness of the barrel link is not less than 3 mm.
Preferably, the hall sensor has a through hole extending in the left-right direction, an external thread is provided on the outer periphery of one end of the cartridge connecting portion, the locking portion has a locking portion inner hole extending in the left-right direction and having an internal thread, and one end of the cartridge connecting portion is connected with the locking portion by a thread after passing through the through hole.
Preferably, the isolation sampler further comprises a sleeve, a sleeve inner hole extending in the left-right direction is formed in the sleeve, the sleeve penetrates through the cylinder extending through hole to be arranged in the cylinder connecting portion, and the sleeve inner hole is used for penetrating through a lead to be tested.
Preferably, the isolation cylinder is made of polyimide, and the sleeve is made of polytetrafluoroethylene.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
FIG. 1 is an X-ray tube filament drive circuit diagram according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of a control unit according to an embodiment of the present invention;
fig. 3 is a schematic diagram of the structure of a filament isolation transformer according to an embodiment of the present invention;
fig. 4 is a front view of a filament isolation transformer according to an embodiment of the present invention;
fig. 5 is an exploded view of the structure of a filament isolation transformer according to an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of an insulating framework according to an embodiment of the invention;
FIG. 7 is a schematic diagram of an isolated sampler according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of an isolated sampler according to an embodiment of the present invention;
fig. 9 is an exploded view of an isolation sampler according to an embodiment of the present invention.
Reference numerals:
a control unit 10, a closed loop control module 110, a PWM control module 120, a drive module 130,
a power supply unit 20, a power frequency rectifying and filtering module 210, a high frequency inversion module 220,
a filament-isolating transformer 30 is provided,
a core 310, a half core 311, a lateral connecting portion 3111, a winding portion 3112, a core fixing hole 3111a,
a primary coil 320, a primary tube 321, a primary coil 322,
the secondary coil 330, the insulating layer 331,
an insulating frame 340, a cylindrical portion 341, an extension portion 342, a core through hole 343,
a high-frequency rectifying-filtering unit 40,
the sampler 50 is isolated from the water and,
the insulating cylinder (51) is set in a state that,
a tube connecting portion 511, a tube extension 5111, a tube extension through hole 5112, a flange 5113,
the locking portion 512, the locking portion inner bore 5121,
the hall sensor 52, the perforations 521,
the length of the sleeve 53, the sleeve inner bore 531,
the X-ray tube E is provided with an X-ray tube,
the filament F is provided with a filament winding,
the fuel tank (T) is provided with a fuel tank,
the left-right direction D1 is,
the front-to-back direction D2,
up-down direction D3.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the following, a filament driving circuit according to an embodiment of the present invention is described with reference to the accompanying drawings, and fig. 1 discloses a diagram of an X-ray tube filament driving circuit according to an embodiment of the present invention. The filament driving circuit of the embodiment of the invention can be used for driving no matter the cathode of the X-ray tube is connected with high voltage, low voltage or ground. The filament driving circuit specifically comprises a control unit 10, a power supply unit 20, a filament isolation transformer 30, a high-frequency rectifying and filtering unit 40 and an isolation sampler 50.
The output end of the control unit 10 is connected with the input end of the power supply unit 20, the output end of the power supply unit 20 is connected with the input end of the filament isolation transformer 30, the output end of the filament isolation transformer 30 is connected with the input end of the high-frequency rectifying and filtering unit 40, the output end of the high-frequency rectifying and filtering unit 40 is connected with the X-ray tube E, the input end of the isolation sampler 50 is connected with the high-frequency rectifying and filtering unit 40, and the output end of the isolation sampler 50 is connected with the control unit 10.
The power supply unit 20 is used to supply power to the filament F. The control unit 10 is configured to control the power supply unit 20 to output the first filament heating voltage. The filament isolation transformer 30 is used to convert the received first filament heating voltage into a second filament heating voltage, and to realize primary and secondary isolation. The high-frequency rectifying and filtering unit 40 is configured to convert the received second filament heating voltage into a dc filament heating voltage and output the dc filament heating voltage to the filament F. The isolated sampler 50 is used to collect the filament current and feed back the current sampling signal to the control unit 10.
When the cathode of the X-ray tube is connected to a high voltage, the filament isolation transformer 30 and the isolation sampler 50 can isolate the superposition from the high voltage of the filament F and the external circuit, thereby avoiding the damage of the high voltage to the external circuit. When the filament F is connected to a low voltage, the filament isolation transformer 30 and the isolation sampler 50 can also isolate the low voltage output by the filament F from the external circuit. The filament drive circuit may also be used to drive the heating of the filament when the filament F is grounded.
Compared with the traditional high-frequency alternating current pulse power supply mode, the X-ray imaging system has the advantage of direct current and constant current, and is driven by the constant current with small fluctuation amplitude, so that the tube current ripple of the X-ray tube is small, and the X-ray imaging system has better imaging quality.
Compared with the traditional direct current power supply mode, the invention has the advantage of high voltage isolation, overcomes the inherent defect of the direct current power supply mode, and can be used for a filament F with a grounded cathode and a filament F with a cathode connected with negative high voltage.
Therefore, the filament driving circuit is a direct current constant current driving circuit with the cathode connected with high voltage, low voltage or grounded, and has the advantages of convenient access, stable constant current and small ripple.
As shown in fig. 1, fig. 1 shows a circuit diagram of the cathode at a high voltage, and the cathode at a low voltage is the same as the circuit diagram of fig. 1 and thus is not shown in detail.
The filament isolation transformer 30 is used to realize high voltage isolation between the filament output and the filament input, and magnetically couple the first filament heating voltage to the secondary side of the filament isolation transformer 30, so that the filament constant current source can be superposed to the high voltage of the X-ray tube E, and the filament isolation transformer 30 is used to realize the insulation strength between the primary side and the secondary side not lower than 80 KV.
The isolation sampler 50 samples the high voltage circuit and simultaneously achieves an isolation insulation strength equivalent to that of the filament isolation transformer 30.
The power supply unit 20 includes a power frequency rectifying and filtering module 210 and a high frequency inverting module 220, an input end of the power frequency rectifying and filtering module 210 is connected to the mains supply, an output end of the power frequency rectifying and filtering module 210 is connected to an input end of the high frequency inverting module 220, and an output end of the high frequency inverting module 220 is connected to an input end of the filament isolation transformer 30. The power frequency rectifying and filtering module 210 receives the commercial power and converts the commercial power into a first voltage, and the high frequency inverting module 220 receives the first voltage and converts the first voltage into a first filament heating voltage and outputs the first filament heating voltage to the filament isolation transformer 30.
Specifically, the power frequency rectifying and filtering module 210 rectifies the incoming commercial power into a dc bus voltage and performs filtering and smoothing to form a first voltage. The commercial power can be AC220V, 50Hz alternating current. The high frequency inverter module 220 converts the received first voltage into a high frequency square wave, i.e., a first filament heating voltage.
Specifically, the power frequency rectifying and filtering module 210 may include a power frequency rectifying module and a filtering module, the power frequency rectifying module and the filtering module are connected in series, and an output end of the power frequency rectifying module is connected to an input end of the filtering module. The power frequency rectification module can be a bridge rectification circuit, and the direct current output end of the bridge rectification circuit is connected with the input end of the filtering module. The filtering module can be formed by connecting an electrolytic capacitor and a polypropylene capacitor (CBB capacitor) in parallel, wherein the electrolytic capacitor is used for smoothing direct-current low-frequency pulsation and reducing low-frequency ripples, and the CBB capacitor is used for filtering partial high-frequency noise in series of a power grid.
Specifically, the high-frequency inverter module 220 may adopt any one of isolated topologies such as forward, flyback, push-pull, half-bridge, full-bridge, etc., a switching tube in the high-frequency inverter module 220 may adopt a power MOS tube with 600V withstand voltage, a dc bus voltage input at a front stage is converted into a high-frequency square wave through the high-frequency inverter module 220, and the high-frequency square wave is connected to a primary coil of the filament isolation transformer 30.
The control unit 10 further includes a closed-loop control module 110, a PWM control module 120, and a driving module 130, wherein an input end of the closed-loop control module 110 is connected to an output end of the isolation sampler 50, an output end of the closed-loop control module 110 is connected to the input end 120 of the PWM control module, an output end of the PWM control module 120 is connected to an input end of the driving module 130, an output end of the driving module 130 is connected to an input end of the power supply unit 20, and specifically, an output end of the driving module 130 is connected to an input end of the high-frequency inversion module 220. The isolation sampler 50 collects a filament current in a filament circuit and outputs a current sampling signal, the closed-loop control module 110 receives the current sampling signal and outputs an output control level signal, the PWM control module 120 receives the control level signal and outputs a PWM signal, and the driving module 130 receives the PWM signal and outputs a driving signal to drive the high-frequency inverter module 220. Specifically, the closed-loop control module 110 may implement closed-loop control of the constant current of the filament F, the PWM signal output by the PWM control module 120 has a variable pulse width, and the driving module 130 receives the PWM signal and amplifies the PWM signal to form a driving signal to drive the high-frequency inverter module 220. In the present embodiment, the filament driving circuit is applied to an X-ray generating apparatus and drives and heats a filament in the X-ray tube E. Specifically, the filament isolation transformer 30, the high-frequency rectification filter unit 40, the isolation sampler 50 and the X-ray tube E including the filament F are arranged in the insulating oil tank T in an insulating manner, and the oil tank T is filled with insulating oil, so that high-voltage withstand voltage of the oil tank T is realized, and effective heat dissipation is realized.
The filament isolation transformer 30 in the present embodiment is described below with reference to fig. 3-6.
As shown in fig. 3 to 6, the filament-isolating transformer 30 includes a magnetic core 310, a primary winding 320, a secondary winding 330, and an insulating bobbin 340.
Specifically, the magnetic core 310 includes two symmetrical half magnetic cores 311, and the half magnetic cores 311 include a transverse connection portion 3111 and a winding portion 3112, and the winding portion 3112 is formed by extending from two ends of the transverse connection portion 3111 to one side. The winding portion 3112 preferably extends vertically, the winding portion 3112 is perpendicular to the lateral connecting portion 3111, and the winding portions 3112 at both ends of the lateral connecting portion 3111 may have the same or different extension lengths.
The ends of the wound portions 3112 of the two half cores 31 abut against each other to form the core 310, and one side of the core 310 is used for mounting the primary coil 320, and the other side is used for mounting the secondary coil 330. Specifically, the primary coil 320 is fitted around the wound portion 3112 on one side of the magnetic core 310, the insulating bobbin 340 is fitted around the wound portion 3112 on the other side of the magnetic core 310, and the secondary coil 330 is provided on the cylindrical portion 341 of the insulating bobbin 340. Because of the position relationship of the abutting positions of the two half magnetic cores 31, the primary coil 320, the insulating framework 340 and the secondary coil 330 are convenient to install, and the primary coil 320 and the insulating framework 340 are firstly sleeved in and then abut against and fix the two half magnetic cores 31.
The insulating frame 340 further includes extension portions 342 extending outward from both ends of the cylindrical portion 341, and the extension portions 342 are provided to increase a high voltage creepage distance and prevent high voltage creepage.
Therefore, the primary and the secondary of the filament isolation transformer 30 are well isolated, the high voltage of the secondary cannot be transmitted to the primary, so that the high voltage is isolated from the filament control circuit in an insulating way, the insulating strength between the primary and the secondary is not lower than 80KV, the filament transformer 30 adopts a high-frequency working mode, and the transformer is small in size, light in weight, simple in structure and convenient to install in a high-pressure oil tank with a small space.
In addition, the magnetic core 310 in the invention adopts a UU-shaped magnetic core structure, namely a double U-shaped magnetic core, and the primary and the secondary are separately wound to realize high-voltage isolation.
In the present embodiment, the insulating skeleton 340 is prepared using polyimide, in which the thickness of the cylindrical portion 341 is not less than 3 mm. Polyimide is an organic high polymer material and has high insulating property, the dielectric strength of the polyimide is 100-300KV/mm, the actually measured dielectric strength is also greater than 30KV/mm, and multiple tests prove that the insulating framework adopts polyimide, so that the insulating property is good. The thickness of the cylindrical portion 341 of the insulating skeleton 34 is not less than 3 mm, and the isolation effect is better. The cylindrical portion 341 is further provided with a core through hole 343 in the longitudinal direction for inserting the wound portion 3112.
In the embodiment, the extending distance and the thickness of the extending portion 342 are both less than 3 mm, which effectively prevents creepage.
In the present embodiment, the secondary coil 330 is externally coated with an insulating layer 331, the insulating layer 331 is made of silicon rubber having a withstand voltage of not less than 10KV, and the silicon rubber insulating layer further isolates high voltage.
In this embodiment, the primary coil 320 includes a primary tube 321 and a primary coil 322 wound around the primary tube 321, the primary tube 321 is sleeved on the wound portion 3112, and the primary tube 321 supports the primary coil 322 and separates the primary coil 322 from the magnetic core 310. The primary tube portion 321 may be a paper tube.
In this embodiment, a core fixing hole 3111a is provided in the longitudinal direction of the wound portion 3112, and the core holder 350 is fixed to the core fixing holes 3111a of the two half cores 311 through the holes.
Specifically, the core holder 350 includes a screw 351, a nut 352, and a spacer 353, the spacer 353 is attached to the back surface of the lateral connecting portion 3111, and the screw 351 passes through the spacer 353 and the core 310 and is fixed by the nut 352. The filament isolation transformer 30 is fastened in a detachable screw compression joint mode, and is convenient to install and detach.
Since the magnetic core 310 is fragile and inconvenient to process, the magnetic core fixing hole 3111 is provided at the outer circumferential surface, specifically, the magnetic core fixing hole 3111a is provided along the length direction of the wound portion 3112 of the half magnetic core 311 and near the outer circumferential surface of the wound portion 3112.
An isolated sampler 50 according to an embodiment of the invention is described below with reference to fig. 7-9.
Fig. 7 shows a schematic structural diagram of the isolation sampler 50, where the direction along the length direction of the wire to be tested is defined as a left-right direction D1, the direction in the horizontal direction perpendicular to the length direction of the wire to be tested is defined as a front-back direction D2, and the direction in the vertical direction perpendicular to the length direction of the wire to be tested is defined as a top-bottom direction D3.
The isolation sampler 50 includes an isolation cylinder 51 and a hall sensor 52. The isolation cylinder 51 comprises a cylinder connecting part 511 and a locking part 512, wherein the cylinder connecting part 511 comprises a cylinder extension 5111 extending along the left-right direction D1, the hall sensor 52 is sleeved on the cylinder extension 5111, one end of the cylinder connecting part 511 penetrates through the hall sensor 52 and is matched and fixed with the locking part 512, a cylinder extension through hole 5112 extending along the left-right direction D1 is formed in the cylinder extension 5111, and the cylinder extension through hole 5112 is used for penetrating through a wire to be tested so that the hall sensor 52 can perform isolation sampling on the current on the wire to be tested.
The hall sensor 52 can measure any waveform of current and voltage, such as: direct current, alternating current, pulse waveforms, etc., and even measurements of transient peaks. The voltage measured by the common Hall sensor 52 is inaccurate when the voltage is over several kilovolts, but the voltage measured by the isolation sampler 50 can reach over 80KV, so that high-voltage isolation is realized. In addition, there are also related high-voltage isolation structures in the prior art, including the conductor that links to each other with the wire that awaits measuring and establish insulating sleeve pipe in conductor periphery cover, or the conductive copper bar that links to each other with the wire that awaits measuring and set up the insulating protective sheath on the copper conductive bar, these structures all still need pass through the conductor switching, and the structure is complicated. Compared with the isolation sampler 50, the isolation sampler 50 has a simple and small structure, and can be quickly installed and detached. When the isolated sampler 50 is applied to a filament driving circuit, the isolated sampler 50 can be used for detecting voltage regardless of whether the cathode of the X-ray tube is connected with high voltage, low voltage or ground, and the space occupied by the isolated sampler 50 in an oil tank is small.
The common filament driving circuit adopts a high-frequency alternating current pulse mode to heat the filament, has the advantage of convenient access, and has more obvious advantages when the cathode of an X-ray tube is connected with high voltage. However, compared with a direct current constant current driving mode, the current fluctuation amplitude of a high-frequency alternating current pulse mode is large, and the tube current ripple of the X-ray tube is large, so that the final imaging quality is influenced. When the cathode of the X-ray tube is not high in voltage or the cathode is grounded, the direct current constant current driving mode well makes up the defect of large fluctuation amplitude of the high-frequency alternating current pulse mode. However, the conventional dc constant current driving method cannot operate when the cathode of the X-ray tube is connected to a high voltage. When the cathode of the X-ray tube is connected with high voltage, the high voltage is sent to the filament driving circuit to damage part of the control circuit.
The other end of the cylinder connecting portion 511 has a flange 5113 extending outward in the radial direction of the cylinder extension 5111 from the end. The flange 5113 and the cylinder extension 5111 can be integrally formed, and the end of the cylinder extension 5111 is bent outwards to form the flange 5113. The flange 5113 and the cylinder extension 5111 can be spliced according to actual needs. The flange 5113 can increase the creepage distance between the hall sensor and the lead to be tested, and prevent high-voltage creepage.
The thickness of the cylinder extension 5111 is more than 3 mm. The insulation distance between the hall sensor 52 and the lead to be tested is set to be more than 3 mm, so that high-voltage isolation is further ensured.
The hall sensor 52 has a through hole 521 extending in the left-right direction D1, an external thread is provided on the outer periphery of one end of the cylinder connecting portion 511, the lock portion 512 has a lock portion inner hole 5121 extending in the left-right direction D1 and having an internal thread, and one end of the cylinder connecting portion 511 is screwed to the lock portion 512 after passing through the through hole 521. The connection of the structure similar to a threaded nut is convenient to assemble and disassemble.
The length of the cylinder extension 5111 is greater than that of the through hole 521, and the difference between the inner diameter of the through hole 521 and the outer diameter of the cylinder extension 5111 is not higher than 0.2 mm.
The thickness of the locking portion 512 is not less than the shoulder thickness of the flange 5113. The thickness of the locking portion 512 refers to the ring thickness of the locking portion 512, and the shoulder thickness of the flange 5113 refers to the height of the outer peripheral surface of the flange 5113 relative to the barrel extension 5111. The thickness of the locking portion 512 and the shoulder thickness of the flange 5113 are as high as necessary to prevent creepage.
The cylinder extension 5111 is in clearance fit with the lead to be tested, and the difference between the inner diameter of the cylinder extension through hole 5112 and the outer diameter of the lead to be tested is higher than 0.2 mm.
The insulating cylinder 51 is made of polyimide. The polyimide is an organic polymer material and has high insulation performance, the dielectric strength of the polyimide is 100-order 300KV/mm, the actually measured dielectric strength is also greater than 30KV/mm, and the isolation cylinder 51 is made of polyimide and has good isolation performance.
The insulation sampler 50 further includes a sleeve 53, the sleeve 53 having a sleeve inner hole 531 extending in the left-right direction, the sleeve 53 passing through the tube extension through hole 5112 to be disposed in the tube connecting portion 511, and the wire to be tested passing through the sleeve inner hole 531. The sleeve 53 and the isolation cylinder 51 form a composite isolation structure, so that the insulation effect is better. The sleeve 53 can be made of a hard teflon material, and after the wire to be tested passes through the sleeve 53, the sleeve 53 has a protection effect on the wire to be tested.
Claims (13)
1. An X-ray tube filament drive circuit for driving a filament having a cathode connected to a high voltage, a low voltage or ground, comprising:
the control unit is connected with the power supply unit and used for controlling the power supply unit to output a first filament heating voltage;
the filament isolation transformer is connected with the power supply unit and is used for converting the received first filament heating voltage into a second filament heating voltage;
the high-frequency rectifying and filtering unit is connected with the filament isolation transformer and is used for converting the received second filament heating voltage into direct-current filament heating voltage and outputting the direct-current filament heating voltage to the filament;
one end of the isolation sampler is connected with the high-frequency rectifying and filtering unit, and the other end of the isolation sampler is connected with the control unit and used for collecting filament current and feeding back a current sampling signal to the control unit;
when the cathode is connected with high voltage or low voltage, the high voltage or low voltage superposed on the filament is transmitted to the filament isolation transformer and the isolation sampler through the high-frequency rectification filter unit and is isolated by the filament isolation transformer and the isolation sampler.
2. The X-ray tube filament drive circuit of claim 1, wherein the power supply unit further comprises a power frequency rectifying and filtering module and a high frequency inverting module,
the power frequency rectifying and filtering module receives commercial power and converts the commercial power into first voltage, and transmits the first voltage to the high-frequency inversion module connected with the power frequency rectifying and filtering module,
the high-frequency inversion module is connected with the control unit, receives the first voltage and converts the first voltage into a first filament heating voltage.
3. The X-ray tube filament drive circuit of claim 2, wherein the control unit further comprises a closed loop control module, a PWM control module, and a drive module,
one end of the closed-loop control module is connected with the isolation sampler, the closed-loop control module outputs a control level signal according to a current sampling signal output by the isolation sampler, the other end of the closed-loop control module is connected with the PWM control module, the PWM control module outputs a PWM signal according to the control level signal,
one end of the driving module is connected with the PWM control module, the other end of the driving module is connected with the high-frequency inversion module, and a driving signal is output according to the PWM signal to drive the high-frequency inversion module.
4. The X-ray tube filament drive circuit of claim 3, comprising: the filament isolation transformer, the high-frequency rectification filter unit, the isolation sampler and the X-ray tube comprising the filament are arranged in the insulating oil tank in an insulating way.
5. The X-ray tube filament drive circuit of claim 4, wherein the filament isolation transformer comprises a magnetic core,
the magnetic core comprises two symmetrical half magnetic cores, each half magnetic core comprises a transverse connecting part and a winding part formed by extending from two ends of the transverse connecting part to one side, the end parts of the winding parts of the two half magnetic cores are abutted to form the magnetic core,
a primary coil is sleeved on the winding part at one side of the magnetic core,
the winding part of the other side of the magnetic core is sleeved with an insulating framework, a barrel part of the insulating framework is provided with a secondary coil, and the insulating framework further comprises extending parts which extend outwards from two ends of the barrel part.
6. The X-ray tube filament driving circuit according to claim 5, wherein the insulating bobbin is made of polyimide, wherein the thickness of the cylindrical portion is not less than 3 mm.
7. The X-ray tube filament driving circuit according to claim 6, wherein the extension distance and the thickness of the extension portion are both not less than 3 mm.
8. The X-ray tube filament driving circuit according to claim 7, wherein the secondary coil is coated with an insulating layer made of silicone rubber having a withstand voltage of not less than 10 KV.
9. The X-ray tube filament driving circuit according to claim 4 or 7, wherein the isolation sampler comprises a Hall sensor and an isolation cylinder with a cylinder connecting part and a locking part, the cylinder connecting part is provided with a cylinder extension extending along the left-right direction, one end of the cylinder connecting part penetrates through the Hall sensor and is matched and fixed with the locking part, a cylinder extension through hole extending along the left-right direction is formed in the cylinder extension, and the cylinder extension through hole is used for a lead to be tested to penetrate through so that the Hall sensor can conduct isolation sampling on current on the lead to be tested.
10. The X-ray tube filament drive circuit according to claim 9, wherein the other end of the barrel connection portion has a flange extending radially outward from the end portion along the barrel, and the barrel connection portion has a thickness of not less than 3 mm.
11. The X-ray tube filament driving circuit according to claim 10, wherein the hall sensor has a through hole extending in the left-right direction, an external thread is provided on the outer periphery of one end of the tube connecting portion, the locking portion has a locking portion inner hole extending in the left-right direction and having an internal thread, and one end of the tube connecting portion is screwed to the locking portion after passing through the through hole.
12. The X-ray tube filament driving circuit according to claim 11, wherein the isolated sampler further comprises a bushing having a bushing inner hole extending in a left-right direction, the bushing passing through the tube extension through hole to be disposed in the tube connection portion, the bushing inner hole being adapted to pass through a lead wire to be tested.
13. The X-ray tube filament drive circuit of claim 12 wherein the isolation cylinder is made of polyimide and the sleeve is made of polytetrafluoroethylene.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010003726.6A CN113079616A (en) | 2020-01-03 | 2020-01-03 | X-ray tube filament driving circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010003726.6A CN113079616A (en) | 2020-01-03 | 2020-01-03 | X-ray tube filament driving circuit |
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| CN113079616A true CN113079616A (en) | 2021-07-06 |
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| CN202010003726.6A Pending CN113079616A (en) | 2020-01-03 | 2020-01-03 | X-ray tube filament driving circuit |
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Cited By (1)
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| CN113839560A (en) * | 2021-08-23 | 2021-12-24 | 安徽明辨电子科技有限公司 | Filament power based on high-voltage floating sampling |
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