CN116961380A - Control circuit and method with high-frequency inverter power supply output for X-ray machine - Google Patents
Control circuit and method with high-frequency inverter power supply output for X-ray machine Download PDFInfo
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- CN116961380A CN116961380A CN202310726662.6A CN202310726662A CN116961380A CN 116961380 A CN116961380 A CN 116961380A CN 202310726662 A CN202310726662 A CN 202310726662A CN 116961380 A CN116961380 A CN 116961380A
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- 238000005070 sampling Methods 0.000 claims abstract description 15
- 239000003990 capacitor Substances 0.000 claims description 16
- 238000004804 winding Methods 0.000 claims description 9
- 230000000694 effects Effects 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
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- 210000003128 head Anatomy 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/122—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for inverters, i.e. dc/ac converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/539—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency
- H02M7/5395—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency by pulse-width modulation
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- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention provides a control circuit and a method with high-frequency inverter power supply output for an X-ray machine, comprising the following steps: the reference voltage circuit inputs a reference voltage signal to the pulse width modulation circuit through reference enabling signal enabling, the sampling feedback circuit collects a voltage signal of the machine head of the X-ray machine and outputs a voltage feedback signal to the pulse width modulation circuit, the pulse width modulation circuit outputs a high-frequency PWM signal through PWM modulation control on the reference voltage signal and the voltage feedback signal, and the inversion driving circuit outputs the high-frequency driving signal to drive the inversion circuit switch to be alternately conducted, so that a high-frequency alternating current power supply is provided for the high-voltage transformer. According to the invention, the inversion driving circuit amplifies two paths of high-frequency PWM signals output by the pulse width modulation circuit, and the inversion driving circuit is driven to be alternately conducted to realize high-frequency inversion of the high-voltage power supply, so that the effects of reducing the volume of the high-voltage power supply circuit, improving the power density and meeting the application requirements of an oral X-ray machine are achieved.
Description
Technical Field
The invention relates to the technical field of high-voltage power supply of medical X-ray machines, in particular to a control circuit and a control method for an X-ray machine, wherein the control circuit is provided with a high-frequency inverter power supply output.
Background
The power supply of the X-ray machine can be divided into a filament power supply and a high-voltage power supply, wherein the filament power supply is used for heating filaments of an X-ray tube, the high-voltage primary voltage of the high-voltage power supply is boosted by a high-voltage transformer and rectified by a high-voltage rectifier to become direct-current high-voltage, the direct-current high-voltage power supply is applied to the cathode and anode of the X-ray tube through a high-voltage cable to generate a high-voltage electric field, the high-voltage primary voltage is alternating-current voltage, direct-current in a high-voltage primary power supply circuit needs to be inverted into alternating-current by an inverter circuit, however, the traditional inverter device generally adopts an LLC structure, and because the inverter device adopts components such as an inductor, a capacitor, a rectifier bridge and the like with high power, the inverter circuit is large in size and low in efficiency, and cannot be applied to the high-voltage power supply which is used by the oral X-ray machine and has high requirements on miniaturization.
In addition, the power supply circuit of the primary side of the high-voltage transformer of the existing oral cavity X-ray machine directly inputs the modulation signal to the high-voltage transformer, the secondary side of the high-voltage transformer outputs high-frequency alternating current up to 5kv, and the chip power supply used by the power supply circuit and all power supplies of the circuit adopt low-voltage direct current, so that the interference among all circuits is large.
Disclosure of Invention
The control circuit and the control method for the output of the high-frequency inverter power supply of the X-ray machine are mainly used for solving the problems that the existing inverter device is high in power and size, cannot be applied to a high-voltage power supply of an oral X-ray machine, is large in circuit interference and the like, and therefore the effects of miniaturization design, high inverter efficiency and interference reduction of the inverter circuit for the high-voltage power supply of the oral X-ray machine are achieved.
The invention realizes the above purpose through the following technical scheme:
the control circuit with the high-frequency inverter power supply output for the X-ray machine comprises a reference voltage circuit, a sampling feedback circuit, a pulse width modulation circuit, an inversion driving circuit and an inversion circuit, wherein the reference voltage circuit is connected with a control unit of the X-ray machine, the control unit outputs a reference enabling signal to an input end of the reference voltage circuit, the reference voltage circuit is connected with the reference voltage signal and enables the reference voltage signal to be input to a second input end of the pulse width modulation circuit through the reference enabling signal, the sampling feedback circuit is used for collecting a voltage signal of a machine head of the X-ray machine and outputting a voltage feedback signal to a first input end of the pulse width modulation circuit, the pulse width modulation circuit is used for carrying out PWM modulation control on the reference voltage signal and the voltage feedback signal and outputting a first high-frequency PWM signal and a second high-frequency PWM signal to the inversion driving circuit, the phase difference between the first high-frequency PWM signal and the second high-frequency PWM signal is 180 degrees, the inversion driving circuit is used for respectively carrying out PWM control on the first high-frequency PWM signal and the second high-frequency PWM signal to the inversion driving circuit through a switch, and the high-frequency AC switch is used for enabling the first high-frequency switch to drive the X-ray machine to be alternately turned on the high-frequency switch.
The reference voltage circuit comprises a first transistor and a first potentiometer, wherein the grid electrode of the first transistor is connected with the reference enabling signal, the drain electrode of the first transistor is connected with the reference voltage signal, the source electrode of the first transistor is grounded, the control unit outputs the low-level reference enabling signal to enable the first transistor to be conducted, the first potentiometer is connected in parallel with the drain end and the source end of the first transistor, and the reference voltage signal value is changed by adjusting the first potentiometer.
The sampling feedback circuit comprises a first operational amplifier and a second operational amplifier, wherein the positive electrode of the voltage feedback signal is filtered and then input into the non-inverting input end of the first operational amplifier, the negative electrode of the voltage feedback signal is filtered and then input into the inverting input end of the first operational amplifier, the first operational amplifier is used for amplifying the voltage feedback signal, the output end of the first operational amplifier is connected with the non-inverting input end of the second operational amplifier, the inverting input end of the second operational amplifier is connected with the output end of the second operational amplifier to form a negative feedback circuit, and the non-inverting input end of the second operational amplifier is connected with the first input end of the pulse width modulation circuit.
Further, the pulse width modulation circuit adopts a pulse width modulation chip with the model number of TL 594.
The frequency setting pin of the pulse width modulation circuit is externally connected with a second potentiometer, and the oscillating frequency of the oscillator arranged in the pulse width modulation chip is set by adjusting the second potentiometer, so that the switching frequency of the chip is 300kHz.
The fault protection circuit comprises a second transistor, a third transistor and a first diode, wherein the control unit outputs an error signal to the cathode end of the first diode, the anode end of the first diode is respectively connected with the drain electrode of the second transistor and the grid electrode of the third transistor, the grid electrode of the second transistor is connected with the reference enabling signal, the source electrode of the second transistor is grounded, the drain electrode of the third transistor is connected with a reference voltage, the source electrode of the third transistor is connected with a dead time setting pin of the pulse width modulation circuit, when the error signal is input to be at a low level, the second transistor is conducted, the reference voltage circuit cuts off the reference enabling signal, the third transistor is conducted, the built-in dead zone comparator of the pulse width modulation chip outputs a high level, and the built-in trigger of the pulse width modulation chip is blocked and locked.
The inverter driving circuit comprises two driving chips, wherein the driving chips are provided with a high-end driving control loop and a low-end driving control loop, a logic processing circuit and a driving circuit are integrated, the high-end driving control loop is used for effectively taking a high-frequency PWM signal input into the logic processing circuit, the driving circuit is used for amplifying a logic control signal output by the logic processing circuit and outputting the high-frequency driving signal to drive a high-end driving switch, the low-end driving control loop is used for effectively taking a high-frequency PWM signal input into the logic processing circuit and amplifying a logic control signal output by the logic processing circuit, and the driving circuit is used for outputting the high-frequency driving signal to drive the low-end driving switch.
The driving chips and the pulse width modulation circuit are grounded, the first switch and the second switch are NMOS tubes, the low-end driving control loops of the two driving chips are respectively connected into the first high-frequency PWM signal and the second high-frequency PWM signal, correspondingly output the first high-frequency driving signal to the control end of the first switch, output the second high-frequency driving signal to the control end of the second switch, the output ends of the first switch and the second switch are respectively connected with two ends of the primary winding of the high-voltage transformer, and the middle tap of the primary winding is connected into a low-voltage power supply and grounded through a polar capacitor.
The phase difference of the first high-frequency driving signal and the second high-frequency driving signal is 180 degrees.
The inverter circuit further comprises a second diode and a third diode, wherein the anode of the second diode is connected with the first high-frequency driving signal, the cathode of the second diode is grounded through a resistor, the anode of the third diode is connected with the second high-frequency driving signal, and the cathode of the third diode is grounded through a resistor.
The control method with high-frequency inverter power supply output for the X-ray machine is applied to the control circuit with high-frequency inverter power supply output for the X-ray machine, and comprises the following steps:
the X-ray machine inputs a starting instruction, the main control module controls the reference voltage circuit to enable the reference voltage circuit to output a reference voltage signal, the pulse width modulation circuit compares the reference voltage signal and the feedback voltage signal through the error amplifier and then outputs a differential signal, the differential signal is compared with a sawtooth wave voltage output by the built-in oscillator of the chip, a high-frequency PWM signal with adjustable pulse width is output, when the high-frequency PWM signal is at a low level, the inversion driving circuit outputs the high-frequency driving signal to drive the first switch of the inversion circuit to be on and the second switch of the inversion driving circuit to be off, and when the high-frequency PWM signal is at a high level, the inversion driving circuit outputs the high-frequency driving signal to drive the second switch of the inversion circuit to be on and the first switch to be off, so that the inversion circuit outputs a high-frequency alternating current signal.
It can be seen that the invention has the following beneficial effects:
1. according to the invention, the inversion driving circuit amplifies two paths of high-frequency PWM signals output by the pulse width modulation circuit, and the two paths of switches of the inversion driving circuit are alternately conducted to realize high-frequency inversion of a high-voltage power supply, wherein the pulse width modulation circuit and the inversion driving circuit adopt integrated chips instead of the traditional inversion device adopting an LLC structure, so that the occupation space of components such as an inductor, a capacitor and a rectifier bridge with higher power is avoided, the volume of the high-voltage power circuit is greatly reduced, the power density of the circuit is improved, and the requirement of an oral X-ray machine on miniaturization of the high-voltage power supply is met;
2. the TL594 pulse width modulation chip adopted by the pulse width modulation circuit has the switching frequency of 300kHz, the frequency of the output high-frequency PWM signal of 150kHz, the high-frequency inversion of a high-voltage power supply is realized, the inversion efficiency of the high-frequency inversion is high, and the stability is good;
3. the invention locks the pulse width modulation circuit through the fault protection circuit when the circuit is in fault, so that the circuit does not output high-frequency modulation wave any more, and timely cuts off the power supply enabling signal sent by the control unit, thereby realizing the secondary protection of the fault;
4. according to the invention, the high-voltage transformer of the X-ray machine is electrically isolated from the power supply control circuit through the inverter circuit, so that the interference of high-voltage alternating current on the power supply control circuit is reduced, and the reliability of the circuit is improved.
The invention is described in further detail below with reference to the drawings and the detailed description.
Drawings
Fig. 1 is a schematic diagram of a high-voltage power supply control circuit with high-frequency inversion according to the present invention.
Fig. 2 is a block diagram of an inverter driving circuit according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without creative efforts, based on the described embodiments of the present invention fall within the protection scope of the present invention.
Control circuit embodiment with high frequency inverter power supply output for X-ray machine
Referring to fig. 1, the control circuit with high-frequency inverter power output for an X-ray machine according to the present invention includes a reference voltage circuit 10, a sampling feedback circuit 20, a pulse width modulation circuit 30, an inverter driving circuit 40, and an inverter circuit 50, the reference voltage circuit 10 is connected to a control unit of the X-ray machine, the control unit outputs a reference enable signal kv_en to an input terminal of the reference voltage circuit 10, the reference voltage circuit 10 is connected to the reference voltage signal and enables the reference voltage signal to be input to a second input terminal of the pulse width modulation circuit 30 through the reference enable signal kv_en, the sampling feedback circuit 20 is used for collecting a voltage signal of the head of the X-ray machine and outputting voltage feedback signals (kv_fb, kv_f) to a first input terminal of the pulse width modulation circuit 30, the pulse width modulation circuit 30 performs PWM modulation control on the reference voltage signal and the voltage feedback signals (kv_fb, kv_f), and outputs a first high-frequency PWM signal DRV1 and a second high-frequency PWM signal DRV2 to the inverter driving circuit 40, the phase difference between the first high-frequency PWM signal DRV1 and the second high-frequency PWM signal DRV2 is 180 degrees, the inverter driving circuit 40 performs logic control on the first high-frequency PWM signal DRV1 and the second high-frequency PWM signal DRV2, and outputs a high-frequency driving signal to the inverter circuit 50, the inverter circuit 50 includes a first switch Q3 and a second switch Q4, and the first switch Q3 and the second switch Q4 are controlled to be alternately turned on by the high-frequency driving signal, so that the inverter circuit 50 outputs a high-frequency ac signal to the primary winding of the high-voltage transformer of the X-ray machine.
Specifically, the control unit in this embodiment is a main control module of the high voltage generating circuit of the X-ray machine, and is configured to control the high voltage power supply to power up, and the filament power supply to power up, and receive the voltage feedback signals (kv_fb, kv_f) and the current feedback signals collected by the sampling feedback circuit 20, where the control unit compares the feedback signal value with a reference value set by the feedback signal value, and when the feedback signal value is in a safety protection range, the control unit outputs a reference enable signal kv_en to the reference voltage circuit 10 according to a power-up instruction, so as to enable the power supply to start, and when the feedback signal value deviates from the safety protection range of the reference value, the control unit determines that the circuit is faulty, outputs an error reporting signal OCP to the fault protection circuit 60, locks the pulse width modulation circuit 30 in time, and cuts off the high frequency output to protect the power supply circuit.
The sampling feedback circuit 20 includes a KV-level voltage sampling circuit and a mA-level current sampling circuit, and samples voltage and current signals of the X-ray machine head in real time.
In this embodiment, the reference voltage circuit 10 includes a first transistor Q7 and a first potentiometer VR4, where a gate of the first transistor Q7 is connected to the reference enable signal kv_en, a drain of the first transistor Q7 is connected to the reference voltage signal, a source of the first transistor Q is grounded, the control unit outputs the low-level reference enable signal kv_en, the first transistor Q7 is turned on, the first potentiometer VR4 is connected in parallel to both ends of a drain and a source of the first transistor Q7, and the reference voltage signal value is changed by adjusting the first potentiometer VR 4.
Specifically, the reference voltage circuit 10 of this embodiment further includes capacitors C46 and C49 and resistors R45, R53, R54, R56, and R57, the gate of the first transistor Q7 is connected to 5V dc through the resistors R45 and R57, the drain is connected to 15V dc through the resistor R53, the capacitor C46 is a polar capacitor, the positive electrode is connected to the first transistor Q7, the negative electrode is grounded, the capacitor C49 is connected in parallel to two ends of the capacitor C46, and the first potentiometer VR4 is connected to the second input end of the pulse width modulation circuit 30 through the resistors R56 and R54.
In this embodiment, the sampling feedback circuit 20 includes a first operational amplifier U7B and a second operational amplifier U7A, the positive electrode kv_fb of the voltage feedback signal is filtered and then input to the non-inverting input terminal of the first operational amplifier U7B, the negative electrode kv_f of the voltage feedback signal is filtered and then input to the inverting input terminal of the first operational amplifier U7B, the first operational amplifier U7B is used for amplifying the voltage feedback signals (kv_fb, kv_f), the output terminal of the first operational amplifier U7B is connected to the non-inverting input terminal of the second operational amplifier U7A, the inverting input terminal of the second operational amplifier U7A is connected to the output terminal thereof to form a negative feedback loop, and the non-inverting input terminal of the second operational amplifier U7A is connected to the first input terminal of the pulse width modulation circuit 30.
Specifically, the sampling feedback circuit 20 of this embodiment further includes capacitors C47 and C50 and resistors R50, R55, R58, R59, R60, R61, and R62, one end of the capacitor C50 is connected to the feedback signal kv_fb, the other end is grounded, the feedback signal is filtered, the non-inverting input end of the first operational amplifier U7B is connected to the 15V dc power supply through the resistors R58 and R59, the feedback signal kv_f is connected to the inverting input end of the first operational amplifier U7B through the resistor R55, and is negatively fed back to the output end of the first operational amplifier U7B, the capacitor C47 is connected in parallel to two ends of the resistor R55, the feedback signal kv_f is filtered, the inverting input end of the first operational amplifier U7B is grounded through the resistor R62, the output end of the first operational amplifier U7A is connected to the non-inverting input end of the second operational amplifier U7A through the resistor R61, and the non-inverting input end of the second operational amplifier U7A is connected to the first input end of the pulse width modulation circuit 30 through the resistor R50.
In this embodiment, the pwm circuit 30 employs a pwm chip model TL 594.
Specifically, the pulse width modulation circuit of the embodiment connects pin 13 and pin 14 of the TL594 chip, and is connected with a 5V reference power supply, so that two transistors built in the TL594 chip are in push-pull type output, and only one of the two transistors is guaranteed to be conducted at a time, namely 180 degrees of phase difference of two paths of high-frequency PWM signals to be output is guaranteed, and the push-pull type output stage not only improves the load capacity of the circuit, but also improves the switching speed.
Specifically, the first input end and the second input end of the pulse width modulation circuit 30 of this embodiment are respectively a group of In1+ and In1+ input ends of an error amplifier built In a TL594 chip, and the width of the high-frequency PWM signal is realized by comparing a control signal output by the error amplifier with a sawtooth voltage output by an oscillator built In the chip, and when the control signal increases, the width of an output pulse decreases.
When the voltage value of the differential positive signal is higher than the sawtooth voltage, a pulse width modulation comparator arranged in the chip outputs high level, a trigger is blocked, and two output transistors are locked through an OR gate.
In this embodiment, the frequency setting pin of the pwm circuit 30 is externally connected to the second potentiometer VR3, and the oscillation frequency of the oscillator built in the pwm chip is set by adjusting the second potentiometer VR3, so that the switching frequency of the chip is 300kHz.
Specifically, in this embodiment, one end of the second potentiometer VR3 is connected to the RT end of the oscillator, the other end is grounded through the resistor R52, one end of the capacitor C44 is connected to the CT end of the oscillator, the other end is commonly grounded with the second potentiometer VR3, and the sawtooth frequency output by the oscillator is: f=1.1/(Rt Ct), the resistance is changed by adjusting the second potentiometer VR3 to change the frequency of the sawtooth wave.
In this embodiment, the fault protection circuit 60 further includes a second transistor Q6, a third transistor Q5, and a first diode D10, where the control unit outputs an error signal OCP to a cathode terminal of the first diode D10, an anode terminal of the first diode D10 is connected to a drain electrode of the second transistor Q6 and a gate electrode of the third transistor Q5, a gate electrode of the second transistor Q6 is connected to a reference enable signal kv_en, a source electrode thereof is grounded, a drain electrode of the third transistor Q5 is connected to a reference voltage, the source electrode is connected to a dead time setting pin of the pulse width modulation circuit 30, and when the error signal OCP is input to a low level, the second transistor Q6 is turned on to enable the reference voltage circuit 10 to cut off the reference enable signal kv_en, and the third transistor Q5 is turned on to enable the pulse width modulation chip built-in dead time comparator to output a high level, and a built-in trigger thereof is blocked and locked.
Referring to fig. 2, in this embodiment, the inverter driving circuit 42 includes two driving chips, where the driving chips are provided with a high-end driving control loop and a low-end driving control loop, and are integrated with the logic processing circuit 41 and the driving circuit 42, the high-end driving control loop takes a high-frequency PWM signal input into the logic processing circuit 41 to be effective, amplifies the logic control signal output from the logic processing circuit 41 by the driving circuit 42, outputs the high-frequency driving signal to drive the high-end driving switch, and the low-end driving control loop takes a high-frequency PWM signal input into the logic processing circuit 41 to be effective, amplifies the logic control signal output from the logic processing circuit 41 by the driving circuit 42, and outputs the high-frequency driving signal to drive the low-end driving switch.
Specifically, the inverter driving circuit 42 of this embodiment further includes a dead time control circuit and a latch circuit 43, an under-voltage protection 44 circuit, and an output circuit 45, where the dead time control circuit is used to avoid false triggering of a power switch control signal in the output circuit during inversion, the latch circuit is used to prevent the power switch in the output circuit from being turned on simultaneously, the under-voltage protection 44 is used to avoid damage to the inverter circuit 50 caused by the under-voltage working state of the circuit, the output circuit 45 is a totem pole output, and the maximum output current can reach 0.8A.
Specifically, the high-end driving control circuit in this embodiment is further provided with a level shift circuit 46 and a pulse filter circuit 47, where the level shift circuit 46 makes the high-end driving control circuit have a stronger anti-interference capability, and the pulse filter circuit 47 is used for signal filtering.
In this embodiment, the two driving chips and the PWM circuit 30 are grounded, the first switch Q3 and the second switch Q4 are NMOS transistors, the low-end driving control loops of the two driving chips are respectively connected to the first high-frequency PWM signal DRV1 and the second high-frequency PWM signal DRV2, and correspondingly output the first high-frequency driving signal to the control end of the first switch Q3, the second high-frequency driving signal to the control end of the second switch Q4, the output ends of the first switch Q3 and the second switch Q4 are respectively connected to two ends of the primary winding of the high-voltage transformer, and the middle tap of the primary winding is connected to a low-voltage power supply and grounded through a polar capacitor.
The phase difference of the first high-frequency driving signal and the second high-frequency driving signal is 180 degrees.
Specifically, in this embodiment, the center tap of the primary winding is connected to a 24V dc power supply, and is connected to the positive poles of the polar capacitors C35 and C39, the polar capacitors C35 and C39 are connected in parallel, and the common negative pole is grounded.
In this embodiment, the inverter circuit 50 further includes a second diode D8, a third diode D9, wherein an anode of the second diode D8 is connected to the first high-frequency driving signal, a cathode thereof is grounded through a resistor, and an anode of the third diode D9 is connected to the second high-frequency driving signal, and a cathode thereof is grounded through a resistor.
Specifically, in this embodiment, if the first switch Q3 and the second switch Q4 are PMOS transistors, the inverter driving circuit selects the high-end driving control circuit to drive the high-frequency PWM signal.
Specifically, the inverter circuit 50 of this embodiment further includes resistors R33, R34, R38 to R41, the cathode of the diode D8 is grounded through the resistors R33, R38, the first high-frequency driving signal is connected to the control end of the first switch Q3 through the resistor R34, the cathode of the diode D9 is grounded through the resistors R40, R39, and the second high-frequency driving signal is connected to the control end of the second switch Q4 through the resistor R41.
Specifically, the secondary of the high-voltage transformer outputs high-frequency alternating current, and then the high-frequency alternating current is rectified through the voltage doubling circuit to output direct-current high voltage, so that the required voltage is provided for ionization of the bulb tube of the X-ray machine.
Control method embodiment with high-frequency inverter power supply output for X-ray machine
The invention relates to a control method with high-frequency inverter power supply output for an X-ray machine, which is applied to a control circuit with high-frequency inverter power supply output for the X-ray machine, and comprises the following steps:
the X-ray machine inputs a starting instruction, the main control module controls the reference voltage circuit 10 to enable the reference voltage circuit to output a reference voltage signal, the pulse width modulation circuit 30 compares the reference voltage signal and the feedback voltage signal through the error amplifier and then outputs a differential signal, the differential signal is compared with a sawtooth wave voltage output by the built-in oscillator of the chip, a high-frequency PWM signal with adjustable pulse width is output, when the high-frequency PWM signal is at a low level, the inversion driving circuit 40 outputs the high-frequency driving signal to drive the first switch Q3 of the inversion circuit 50 to be conducted, the second switch Q4 is disconnected, and when the high-frequency PWM signal is at a high level, the inversion driving circuit 40 outputs the high-frequency driving signal to drive the second switch Q4 of the inversion circuit 50 to be conducted, and the inversion circuit 50 outputs a high-frequency alternating current signal.
Specifically, in this embodiment, when the feedback signal value is greater than the voltage reference signal value, the output end of the error amplifier outputs a differential positive signal, the differential positive signal is compared with the sawtooth voltage, and when the differential positive signal voltage value is higher than the sawtooth voltage value, the pulse width modulation comparator built in the chip outputs a high level, the trigger is blocked, and meanwhile, the output of the high-frequency PWM signal is cut off by locking the two output transistors through the or gate.
Specifically, in this embodiment, when the circuit of the X-ray machine fails, the main control module outputs a low-level signal to enable the fault protection circuit, and at this time, the fault protection circuit outputs a dead zone control signal value greater than the sawtooth voltage value, and the pulse width modulation circuit 30 outputs a high level through the dead zone time comparator, so that the trigger is blocked, and simultaneously locks two output transistors through the or gate, thereby cutting off the output of the high-frequency PWM signal.
The above embodiments are only preferred embodiments of the present invention, and the scope of the present invention is not limited thereto, but any insubstantial changes and substitutions made by those skilled in the art on the basis of the present invention are intended to be within the scope of the present invention as claimed.
Claims (10)
1. A control circuit for an X-ray machine having a high frequency inverter power output, comprising:
the X-ray machine comprises a reference voltage circuit, a sampling feedback circuit, a pulse width modulation circuit, an inversion driving circuit and an inversion circuit, wherein the reference voltage circuit is connected with a control unit of the X-ray machine, the control unit outputs a reference enabling signal to an input end of the reference voltage circuit, the reference voltage circuit is connected with a reference voltage signal and enables the reference voltage signal to be input to a second input end of the pulse width modulation circuit through the reference enabling signal, the sampling feedback circuit is used for collecting a voltage signal of a machine head of the X-ray machine and outputting a voltage feedback signal to a first input end of the pulse width modulation circuit, the pulse width modulation circuit outputs a first high-frequency PWM signal and a second high-frequency PWM signal to the inversion driving circuit through PWM modulation control of the reference voltage signal and the voltage feedback signal, the phase difference of the first high-frequency PWM signal and the second high-frequency PWM signal is 180 degrees, the inversion driving circuit outputs a high-frequency driving signal to the first high-frequency PWM signal and the second high-frequency PWM signal to the first high-frequency switch, the inversion driving circuit alternately turns on the high-frequency switch, and the high-frequency AC power supply winding is turned on to the primary transformer.
2. The control circuit with high frequency inverter power output for an X-ray machine of claim 1, wherein:
the reference voltage circuit comprises a first transistor and a first potentiometer, wherein the grid electrode of the first transistor is connected with the reference enabling signal, the drain electrode of the first transistor is connected with the reference voltage signal, the source electrode of the first transistor is grounded, the control unit outputs the low-level reference enabling signal to enable the first transistor to be conducted, the first potentiometer is connected in parallel with the drain end and the source end of the first transistor, and the value of the reference voltage signal is changed by adjusting the first potentiometer.
3. The control circuit with high frequency inverter power output for an X-ray machine of claim 1, wherein:
the sampling feedback circuit comprises a first operational amplifier and a second operational amplifier, wherein positive electrode of a voltage feedback signal is filtered and then input into a non-inverting input end of the first operational amplifier, negative electrode of the voltage feedback signal is filtered and then input into an inverting input end of the first operational amplifier, the first operational amplifier is used for amplifying the voltage feedback signal, an output end of the first operational amplifier is connected with a non-inverting input end of the second operational amplifier, an inverting input end of the second operational amplifier is connected with an output end of the second operational amplifier to form a negative feedback loop, and a non-inverting input end of the second operational amplifier is connected with a first input end of the pulse width modulation circuit.
4. The control circuit with high frequency inverter power output for an X-ray machine of claim 1, wherein:
the pulse width modulation circuit adopts a pulse width modulation chip with the model TL 594.
5. The control circuit with high frequency inverter power output for an X-ray machine of claim 4, wherein:
the frequency setting pin of the pulse width modulation circuit is externally connected with a second potentiometer, and the oscillating frequency of the oscillator built in the pulse width modulation chip is set by adjusting the second potentiometer, so that the switching frequency of the chip is 300kHz.
6. The control circuit with high frequency inverter power output for an X-ray machine of claim 4, wherein:
the control unit outputs an error signal to the cathode end of the first diode, the anode end of the first diode is respectively connected with the drain electrode of the second transistor and the grid electrode of the third transistor, the grid electrode of the second transistor is connected with the reference enabling signal, the source electrode of the second transistor is grounded, the drain electrode of the third transistor is connected with a reference voltage, the source electrode of the second transistor is connected with a dead time setting pin of the pulse width modulation circuit, when the error signal is input to be at a low level, the second transistor is conducted, the reference enabling signal is cut off by the reference voltage circuit, the third transistor is conducted, the built-in dead zone comparator of the pulse width modulation chip outputs a high level, and the built-in trigger of the pulse width modulation chip is blocked and locked.
7. The control circuit with high frequency inverter power output for an X-ray machine of claim 6, wherein:
the inversion driving circuit comprises two driving chips, the driving chips are provided with a high-end driving control loop and a low-end driving control loop, a logic processing circuit and a driving circuit are integrated, the high-end driving control loop takes high-level effective high-frequency PWM signals input into the logic processing circuit, the driving circuit amplifies logic control signals output by the logic processing circuit and outputs the high-frequency driving signals to drive a high-end driving switch, the low-end driving control loop takes low-level effective high-frequency PWM signals input into the logic processing circuit, and the driving circuit amplifies logic control signals output by the logic processing circuit and outputs the high-frequency driving signals to drive the low-end driving switch.
8. The control circuit with high frequency inverter power output for an X-ray machine of claim 7, wherein:
the two driving chips and the pulse width modulation circuit are grounded together, the first switch and the second switch are NMOS tubes, the low-end driving control loops of the two driving chips are respectively connected with the first high-frequency PWM signal and the second high-frequency PWM signal, correspondingly output the first high-frequency driving signal to the control end of the first switch, output the second high-frequency driving signal to the control end of the second switch, the output ends of the first switch and the second switch are respectively connected with the two ends of the primary winding of the high-voltage transformer, and the middle tap of the primary winding is connected with a low-voltage power supply and grounded through a polar capacitor;
the phase difference of the first high-frequency driving signal and the second high-frequency driving signal is 180 degrees.
9. The control circuit with high frequency inverter power output for an X-ray machine of claim 8, wherein:
the inverter circuit further comprises a second diode and a third diode, wherein the anode of the second diode is connected with the first high-frequency driving signal, the cathode of the second diode is grounded through a resistor, the anode of the third diode is connected with the second high-frequency driving signal, and the cathode of the third diode is grounded through a resistor.
10. A control method with high-frequency inverter power supply output for an X-ray machine, characterized by being applied to the control circuit with high-frequency inverter power supply output for an X-ray machine according to any one of claims 1 to 9, comprising:
the X-ray machine inputs a starting instruction, the main control module controls the reference voltage circuit to enable the reference voltage circuit to output a reference voltage signal, the pulse width modulation circuit compares the reference voltage signal and the feedback voltage signal through the error amplifier and then outputs a differential signal, the differential signal is compared with a sawtooth wave voltage output by the built-in oscillator of the chip, a high-frequency PWM signal with adjustable pulse width is output, when the high-frequency PWM signal is at a low level, the inversion driving circuit outputs the high-frequency driving signal to drive the first switch of the inversion circuit to be on and the second switch of the inversion driving circuit to be off, and when the high-frequency PWM signal is at a high level, the inversion driving circuit outputs the high-frequency driving signal to drive the second switch of the inversion circuit to be on and the first switch to be off, so that the inversion circuit outputs a high-frequency alternating current signal.
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| CN202310726662.6A CN116961380B (en) | 2023-06-19 | 2023-06-19 | Control circuit and method with high-frequency inverter power supply output for X-ray machine |
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| CN116961380B (en) | 2024-05-03 |
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