Neutron control circuit, device and system

Abstract

The invention discloses a neutron control circuit, device and system, relates to the field of circuits, and replaces a trigger pulse shaping drive module, an oscillation circuit module, an oscillation control circuit module, a comparison circuit module, a switching circuit module, a monostable narrow pulse circuit module and the like in the prior art through a single-chip microcomputer. An oscillation driving circuit and a driving isolation circuit in the prior art are replaced by the driving isolation circuit, so that the circuit design is simple, the size of the whole control circuit is reduced, the circuit is clear, elements required by the circuit design are greatly reduced, the integration level is high, and fault judgment and maintenance are easy; the single-chip microcomputer outputs a second control signal to control the high-voltage oscillation circuit to work only after the high-voltage discharge circuit stops working, so that the high-voltage discharge circuit and the high-voltage oscillation circuit are ensured not to work simultaneously, and the risk conditions of large working current and the like caused by the simultaneous working of charging and discharging are avoided; the accuracy and reliability of the neutron source in the application process are improved, and the application range of the neutron source is expanded.

Description

Technical Field

[0001] The present invention relates to the field of circuits, and particularly to a control circuit, device and system for neutrons. Background Art

[0002] With the continuous development of neutron sources, neutron tubes have played an important role in multiple application fields. In particular, they can be applied to the field of oilfield production logging. The neutron logging method is a logging method that is not restricted by casings and tubing, and is an important logging means during the oilfield development period. It can be realized by a PNN (Pulse Neutron Neutron) logging tool. The neutron source used in PNN logging is a controllable pulsed neutron source. Neutrons are generated by the neutron tube. When the control circuit of the neutron tube does not work, no neutrons are generated. Its principle is mainly to control the generation of 3000V DC high voltage to supply power to the PNN neutron generator. The PNN neutron generator controls the neutron tube to work to control neutron bombardment, thereby realizing the utilization of the neutron source.

[0003] In the prior art, please refer to Figure 1 , Figure 1 which is a schematic structural diagram of a control circuit for neutrons provided by the prior art. The control of neutrons is achieved through, for example, Figure 1Implemented by the shown hardware integrated circuit, the peripheral circuit of the control circuit includes a high-voltage oscillation circuit, a 3000V high-voltage generation circuit, a 3000V high-voltage pulse discharge circuit, and a PNN neutron generator. When the high-voltage oscillation circuit receives the control signal output by the control circuit, it controls the 3000V high-voltage generation circuit to output a high voltage of 3000V. The 3000V high-voltage pulse discharge circuit will also quickly pull down the 3000V high voltage when it receives the control signal, thereby generating a negative pulse high voltage of 3000V. When there is a trigger pulse input, the trigger pulse is output to the switch circuit and the monostable narrow pulse circuit after passing through the shaping drive circuit. At this time, the switch circuit allows the oscillation output, and the oscillation control circuit controls the oscillation signal output by the oscillation circuit to be output after passing through the oscillation drive circuit to control the high-voltage oscillation circuit to generate a high voltage of 3000V. At the same time, the voltage output by the 3000V high-voltage generation circuit returns to the voltage sampling circuit, and then the voltage output by the 3000V high-voltage generation circuit is stabilized at about 3000V through the comparison circuit. The narrow pulse signal output by the monostable narrow pulse circuit is output to the 3000V high-voltage pulse discharge circuit after passing through the drive isolation circuit, causing the 3000V high-voltage pulse discharge circuit to work. When the PNN instrument is in the non-firing mode, there is no trigger pulse input, and no 3000V DC high voltage is generated in the circuit. At this time, there is no firing trigger pulse input, the switch circuit outputs a low level to the oscillation control circuit, the oscillation control circuit outputs a low level, turns off the oscillation output, the oscillation drive circuit outputs a low level, the high-voltage oscillation circuit does not work, the output of the 3000V high-voltage generation circuit is zero, and the PNN neutron generator does not work. When the PNN instrument is in the firing mode, the circuit inputs a trigger pulse to control the peripheral circuit to generate a 3000V negative pulse high voltage and send it to the PNN neutron generator to make it work. However, the circuit structure of this hardware control circuit is relatively complex, requiring a large number of components and links, which are interrelated and not easy to understand and widely promote. When there is a fault in the circuit, it is difficult to determine the location of the fault and the repair is difficult. And this method is prone to conflict phenomena where the high-voltage discharge circuit and the high-voltage oscillation circuit work simultaneously during application, resulting in direct discharge to the ground during DC high-voltage charging and the risk of a large working current of the instrument. Summary of the Invention

[0004] The purpose of the present invention is to provide a control circuit, device and system for neutrons, with simple circuit design, reduced volume of the entire control circuit, clear and distinct circuit, greatly reduced components required for circuit design, high integration, easy to judge faults and repair; after the high-voltage discharge circuit stops working, the single-chip microcomputer will output a second control signal to control the high-voltage oscillation circuit to work, ensuring that the high-voltage discharge circuit and the high-voltage oscillation circuit will not work simultaneously, avoiding risk situations such as large working current caused by simultaneous charging and discharging, improving the accuracy and reliability during the application of the neutron source, and expanding the application range of the neutron source.

[0005] To solve the above technical problems, the present invention provides a neutron control circuit, comprising:

[0006] A high-voltage sampling circuit, whose input end is connected to the output end of the high-voltage generating circuit, and whose output end is connected to the first input end of the single-chip microcomputer, for outputting a first voltage signal to the first input end of the single-chip microcomputer, and the first voltage signal is linearly related to the voltage output by the high-voltage generating circuit;

[0007] The single-chip microcomputer, whose second input end receives a trigger pulse, and whose output end is connected to the input end of the drive isolation circuit, for when detecting the trigger pulse, outputting a first control signal to control the operation of the high-voltage discharge circuit; after the high-voltage discharge circuit stops operating, outputting a second control signal to control the operation of the high-voltage oscillation circuit, so that the high-voltage generating circuit operates; detecting the first voltage signal after outputting the second control signal, to determine whether to stop outputting the second control signal based on the first voltage signal and a preset voltage threshold;

[0008] The drive isolation circuit, whose output end is respectively connected to the high-voltage oscillation circuit and the high-voltage discharge circuit.

[0009] Preferably, the high-voltage discharge circuit stops operating, including:

[0010] After the first control signal is output for a first preset time period, it is determined that the high-voltage discharge circuit stops operating.

[0011] Preferably, the high-voltage sampling circuit includes a first voltage-dividing resistor and a second voltage-dividing resistor; the first end of the first voltage-dividing resistor is grounded, the second end is respectively connected to the first end of the second voltage-dividing resistor and the second input end of the single-chip microcomputer, and the second end of the second voltage-dividing resistor is connected to the output end of the high-voltage generating circuit.

[0012] Preferably, the high-voltage oscillation circuit includes a first switch, a transformer, an oscillation resistor, a first oscillation capacitor and a second oscillation capacitor; the control end of the first switch is connected to the output end of the drive isolation circuit, the first end is grounded, the second end is connected to the first end of the primary winding of the transformer, the second end of the primary winding of the transformer is respectively connected to the first end of the oscillation resistor and the first end of the second oscillation capacitor, the second end of the oscillation resistor is connected to the power supply, the second end of the second oscillation capacitor is connected to the first end of the first oscillation capacitor, and the second end of the first oscillation capacitor is grounded;

[0013] The first switch is used to conduct when the single-chip microcomputer outputs the second control signal, so that the high-voltage generating circuit operates; and to turn off when the single-chip microcomputer does not output the second control signal, so that the high-voltage generating circuit stops operating.

[0014] Preferably, the single-chip microcomputer is further configured to,

[0015] After detecting the trigger pulse, determine whether the trigger pulse is detected again within a second preset time period;

[0016] If so, return to the step of outputting the first control signal to control the high-voltage discharge circuit to work;

[0017] If not, stop working.

[0018] Preferably, the detecting the first voltage signal to determine whether to stop outputting the second control signal based on the first voltage signal and a preset voltage threshold includes:

[0019] Receive and detect the first voltage signal;

[0020] Determine whether the first voltage signal is greater than the preset voltage threshold;

[0021] If so, stop outputting the second control signal to control the high-voltage oscillation circuit to stop working;

[0022] If not, continue to output the second control signal and return to the step of receiving and detecting the first voltage signal.

[0023] Preferably, it further includes:

[0024] A protection circuit, the input end of the protection circuit is connected to the trigger pulse, and the output end is connected to the first input end of the single-chip microcomputer.

[0025] Preferably, the protection circuit includes a protection resistor and a voltage stabilizing module; the first end of the protection resistor is connected to the trigger pulse, the second end is respectively connected to the first end of the voltage stabilizing module and the first input end of the single-chip microcomputer, and the second end of the voltage stabilizing module is grounded.

[0026] To solve the above technical problems, the present invention further provides a neutron control device, including a high-voltage oscillation circuit, a high-voltage generation circuit, a high-voltage discharge circuit, and the neutron control circuit as described above;

[0027] The output end of the high-voltage oscillation circuit is connected to the input end of the high-voltage generation circuit, the output end of the high-voltage generation circuit is respectively connected to the first input end of the neutron control circuit, the first input end of the high-voltage discharge circuit, and the input end of the neutron generator, and the output end of the neutron control circuit is respectively connected to the input end of the high-voltage oscillation circuit and the second input end of the high-voltage discharge circuit.

[0028] To solve the above technical problems, the present invention further provides a control system for neutrons, comprising a neutron generator and a control device for neutrons as described above, and the neutron generator is connected to the control device for neutrons.

[0029] The present invention provides a control circuit for neutrons, comprising a high-voltage sampling circuit, a single-chip microcomputer and a drive isolation circuit. The single-chip microcomputer can control the operation of a high-voltage oscillation circuit and a high-voltage discharge circuit according to the received trigger pulse and the first voltage signal, so as to control the generation and discharge of DC high voltage and achieve the effect of controlling neutrons. By replacing multiple modules such as a trigger pulse shaping driver, an oscillation circuit, an oscillation control circuit, a comparison circuit, a switch circuit and a monostable narrow pulse circuit in the prior art with a single-chip microcomputer, and replacing the oscillation drive circuit and the drive isolation circuit in the prior art with a drive isolation circuit, the circuit design is simplified, the volume of the entire control circuit is reduced, the circuit is clear and distinct, the components required for circuit design are greatly reduced, the integration degree is high, and it is easy to judge faults and perform repairs. After the high-voltage discharge circuit stops operating, the single-chip microcomputer will output a second control signal to control the operation of the high-voltage oscillation circuit, ensuring that the high-voltage discharge circuit and the high-voltage oscillation circuit do not operate simultaneously, avoiding risk situations such as large working current caused by simultaneous charging and discharging, improving the accuracy and reliability in the application process of the neutron source, and expanding the application range of the neutron source.

[0030] The present invention further provides a control device and system for neutrons, which have the same beneficial effects as the above control circuit for neutrons. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the prior art and the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 FIG. 15 is a schematic structural diagram of a control circuit for neutrons provided by the prior art;

[0033] Figure 2 FIG. 19 is a schematic structural diagram of a control circuit for neutrons provided by the present invention;

[0034] Figure 3 FIG. 23 is a schematic structural diagram of a control device for neutrons provided by the present invention;

[0035] Figure 4 FIG. 27 is a schematic structural diagram of another control device for neutrons provided by the present invention;

[0036] Figure 5Schematic flowchart of the control process of a neutron control circuit provided by the present invention;

[0037] Figure 6 Schematic diagram of the signal waveform of a trigger pulse provided by the present invention;

[0038] Figure 7 Schematic diagram of the waveform of a control signal provided by the prior art;

[0039] Figure 8 Another schematic diagram of the waveform of a control signal provided by the prior art;

[0040] Figure 9 Schematic diagram of the waveform comparison of a control signal provided by the prior art;

[0041] Figure 10 Another schematic diagram of the waveform comparison of a control signal provided by the prior art;

[0042] Figure 11 Schematic diagram of the structure of a neutron control system provided by the present invention. Detailed implementation manners

[0043] The core of the present invention is to provide a neutron control circuit, device and system, with simple circuit design, reduced volume of the entire control circuit, clear and distinct circuit, greatly reduced components required for circuit design, high integration, easy fault judgment and maintenance; after the high-voltage discharge circuit stops working, the single-chip microcomputer will output a second control signal to control the high-voltage oscillation circuit to work, ensuring that the high-voltage discharge circuit and the high-voltage oscillation circuit will not work simultaneously, avoiding risk situations such as large working current caused by simultaneous charging and discharging, improving the accuracy and reliability in the application process of the neutron source, and expanding the application range of the neutron source.

[0044] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0045] The neutron control circuit provided by this application can control the generation of neutrons, facilitating the implementation of processes such as neutron logging. The generated neutrons can also be applied to other types of work processes, enabling the wide application of neutrons through a controllable pulsed neutron source. When no high voltage is applied, the neutron tube of the neutron generator does not generate fast neutrons. By controlling the high voltage of the neutron generator, the generation of fast neutrons can be controlled. In the field of oilfield production logging, the neutron logging method is a logging method that is not restricted by casings and tubing. It can be used for tasks such as dividing oil, gas, and water layers; finding oil and gas layers that have been overlooked in interpretation; judging the migration of the oil-gas-water interface; evaluating the plugging effect of water-flooded layers; measuring residual oil and residual oil saturation, etc. It is an important logging means during the oilfield development period. Neutron sources used in neutron logging such as PNN are controllable pulsed neutron sources. Neutrons are generated by the neutron tube. When the control circuit of the neutron tube does not work, no neutrons are generated, and no neutron radiation will be caused to on-site workers. In practical applications, the high-voltage generation circuit usually needs to generate a high voltage of 3000V.

[0046] The purpose of this application is to design a control circuit for the high-voltage generation circuit and the high-voltage discharge circuit, thereby achieving a method for controlling neutron generation. On the one hand, it simplifies the circuit design and reduces the components of the circuit. On the other hand, it completely eliminates the logical conflict caused by the possible simultaneous operation of the DC high-voltage generation and discharge processes, which may lead to a large current phenomenon. The specific implementation details are as follows.

[0047] Please refer to Figure 2 , Figure 2 , which is a schematic structural diagram of a neutron control circuit provided by the present invention. To solve the above technical problems, the present invention provides a neutron control circuit 5, including:

[0048] A high-voltage sampling circuit 1, with its input end connected to the output end of the high-voltage generation circuit 2 and its output end connected to the first input end of the single-chip microcomputer U1. It is used to output a first voltage signal to the first input end of the single-chip microcomputer U1, and the first voltage signal is linearly related to the voltage output by the high-voltage generation circuit 2.

[0049] The single-chip microcomputer U1, with its second input end connected to a trigger pulse and its output end connected to the input end of the drive isolation circuit U2. It is used to output a first control signal to control the operation of the high-voltage discharge circuit 3 when a trigger pulse is detected. After the high-voltage discharge circuit 3 stops working, it outputs a second control signal to control the operation of the high-voltage oscillation circuit 4, so that the high-voltage generation circuit 2 works. After outputting the second control signal, it detects the first voltage signal to determine whether to stop outputting the second control signal based on the first voltage signal and a preset voltage threshold.

[0050] The drive isolation circuit U2, with its output end connected to both the high-voltage oscillation circuit 4 and the high-voltage discharge circuit 3.

[0051] Specifically, when the single-chip microcomputer U1 detects a trigger pulse, it first controls the high-voltage discharge circuit 3 to start working, forming a negative pulse to achieve the purpose of controlling neutron generation. After the high-voltage discharge circuit 3 stops working, the single-chip microcomputer U1 controls the operation of the high-voltage oscillation circuit 4 to make the high-voltage generation circuit 2 enter the working state and generate the required high voltage. At the same time, the high-voltage sampling circuit 1 samples the voltage output by the high-voltage generation circuit 2, and then outputs a first voltage signal corresponding to the voltage output by the high-voltage generation circuit 2 to the single-chip microcomputer U1, so that the single-chip microcomputer U1 can judge whether the high-voltage generation circuit 2 outputs voltage through the first voltage signal, and further judge whether the output voltage meets the requirements of the preset voltage threshold. When the first voltage signal meets the requirements, it proves that the high-voltage generation circuit 2 has output the required high voltage at this time. At this time, the operation of the high-voltage oscillation circuit 4 can be stopped, and the high-voltage generation process of the high-voltage generation circuit 2 is completed. The generated high voltage will cooperate with the high-voltage discharge circuit 3 in the follow-up to form the required negative pulse.

[0052] It is not difficult to understand that when the single-chip microcomputer U1 detects the first trigger pulse, since there is no voltage at the output end of the high-voltage generation circuit 2 at this time, the high-voltage discharge circuit 3 cannot carry out the discharge process, but the high-voltage generation circuit 2 will generate high voltage based on the control of the high-voltage oscillation circuit 4. When the single-chip microcomputer U1 detects the second trigger pulse, the high-voltage discharge circuit 3 will first form a negative pulse signal based on the high voltage generated by the high-voltage generation circuit 2 during the first trigger pulse, and then the high-voltage generation circuit 2 will regenerate high voltage based on the second control signal, so that the discharge process of the high-voltage discharge circuit 3 can be realized when the single-chip microcomputer U1 detects the next trigger pulse. This working process is carried out cyclically, realizing the process of controlling neutron generation by the negative pulse when the single-chip microcomputer U1 detects the trigger pulse. Therefore, in practical applications, a trigger pulse can be output in advance so that the subsequent control circuit can correctly control the neutron generation process. It is also possible to adjust the control circuit to the state after receiving the first trigger pulse before application. This application does not make special limitations here and can be adjusted according to the actual application situation.

[0053] There are various implementation methods for the high-voltage sampling circuit 1 to sample the voltage output by the high-voltage generation circuit 2, which can be realized by means of a comparator, a voltage dividing circuit or a differential circuit, etc. Taking the high voltage of 3000V as an example, when the high-voltage output of the high-voltage generation circuit 2 is lower than 3000V, after voltage sampling, the high-voltage sampling circuit 1 outputs a high level. When the high-voltage output of the high-voltage generation circuit 2 is higher than 3000V, after voltage sampling, the high-voltage sampling circuit 1 outputs a low level. This application does not make special limitations on the specific type and implementation method of the high-voltage sampling circuit 1, etc. The output first voltage signal is linearly related to the voltage output by the high-voltage generation circuit 2, and it can reflect the voltage situation of the high-voltage generation circuit 2.

[0054] Considering the working process of the control circuit, when the high-voltage discharge circuit 3 is working, the high-voltage oscillation circuit 4 cannot work, otherwise it will cause the DC high voltage output by the high-voltage generation circuit 2 to directly discharge to the ground during the charging process, resulting in a large working current in the circuit. When the high-voltage discharge circuit 3 is working, the high-voltage electricity stored in the high-voltage generation circuit 2 itself should be used. In the prior art, the separate operation with the oscillation signal is achieved by controlling the pulse width of the narrow pulse. Usually, the narrow pulse generated by the monostable state is set to about 680 nanoseconds. However, affected by the input and output capacitances of the MOS transistors in the high-voltage discharge circuit 3, the pulse width will increase to 1 microsecond to 3 microseconds. Moreover, when the instrument works under high temperature and high pressure, and due to component aging and other reasons, the performance of devices such as resistors and capacitors in the circuit will change, which may cause the pulse width to be wider, resulting in a conflict that the high-voltage oscillation circuit 4 and the high-voltage discharge circuit 3 work simultaneously, resulting in a large working current of the instrument or even the instrument not working. In this application, the first control signal and the second control signal are distinguished to control the high-voltage discharge current and the high-voltage oscillation circuit 4 respectively. And the single-chip microcomputer U1 will control the output of the second control signal only after the high-voltage discharge circuit 3 stops working. The single-chip microcomputer U1 stops the high-voltage discharge circuit 3 from working by stopping the output of the first control signal. Therefore, the first control signal and the second control signal will not be output simultaneously, thus avoiding the simultaneous operation of the high-voltage oscillation circuit 4 and the high-voltage discharge circuit 3. This control method is more accurate and reliable, and can ensure the separate operation of the high-voltage oscillation circuit 4 and the high-voltage discharge circuit 3.

[0055] Specifically, the single-chip microcomputer U1 can adopt a single-chip microcomputer of type U1. Its structure is simple, but it can serve as the core of the entire system to complete multiple functions of the control circuit and is compatible with the minimized design. The respective pins of the single-chip microcomputer U1 can be configured according to the required functions. The selected single-chip microcomputer U1 should have functions such as AD (Analog to Digital) conversion, pulse interruption, be able to output PWM (Pulse Width Modulation) pulse signals, and be able to output narrow pulse signals, such as Figure 3As shown in the figure, the single-chip microcomputer U1 can be an 8-bit high-speed PIC flash single-chip microcomputer. Specifically, the PIC12F1822 model can be selected, with an 8-pin SO8 surface mount package. The single-chip microcomputer chip of this model has an internal power-on reset function, eliminating the external reset circuit, and has a high-precision 32M internal oscillator module, enabling a single instruction cycle to reach 125 nanoseconds, eliminating the external crystal oscillator circuit, making the circuit design very simple and clear, and further reducing the design of the peripheral circuit. Functionally, the chip has two 8-bit and one 16-bit timer / counters, which can meet the timing requirements. Since it can have a high-precision oscillator of up to 32M and a single instruction cycle can reach 125 nanoseconds, it can meet the subsequent requirements for the output of narrow pulses; and the single-chip microcomputer chip has a PWM output function, which can control the automatic output of PWM pulse square waves; at the same time, it has a 10-bit AD acquisition function, which can monitor the analog voltage value output by the high-voltage sampling circuit 1, and also has an external pulse interruption function, which can process trigger events in real time. The specific type and implementation method of the single-chip microcomputer U1 are not particularly limited in this application and can be selected and adjusted according to the actual application situation, as long as the function requirements are met. The specific type and parameters of the PWM signal and narrow pulse signal output by the single-chip microcomputer U1 are not particularly limited in this application. The PWM pulse signal can be a signal with a frequency of 20K Hertz and a duty cycle of 50%, and the narrow pulse signal can be implemented by a pulse signal of about 680 nanoseconds.

[0056] It is not difficult to understand that there are various implementation methods for the single-chip microcomputer U1 to detect trigger pulses, determine whether the high-voltage discharge circuit 3 stops working, and determine the first voltage signal and the preset voltage threshold, etc., which are not particularly limited in this application; in order to ensure the simultaneous output of the first control signal and the second control signal, it can be set that the working process of outputting the first control signal according to the trigger pulse is implemented through an interrupt program. The receiving method of the trigger pulse by the single-chip microcomputer U1 can be implemented through a monostable flip-flop. The monostable flip-flop can cause the circuit output to flip from one stable state to another transient stable state under the action of an external trigger pulse, and then return to the original stable state after a period of time. The maintenance time depends on the parameter values of RC in the circuit; the determination of whether the high-voltage discharge circuit 3 stops working can be achieved through a timer or by detecting the voltage and / or current signals output by the high-voltage discharge circuit 3; the determination process of the first voltage signal and the preset voltage threshold can be achieved through a comparator or a differential circuit, etc. The source and generation method of the trigger pulse are not particularly limited in this application and can be output artificially or set by a program through a pulse generator, etc.

[0057] Specifically, the driving isolation circuit U2 can be implemented by driving a chip or by other forms of driving isolation modules. The specific type and implementation method of the driving isolation circuit U2 are not particularly limited in this application and can be selected and adjusted according to actual application requirements. The driving isolation circuit U2 mainly plays a role in improving the driving ability, enabling the control signal output by the single-chip microcomputer U1 to more accurately and effectively control the high-voltage oscillation circuit 4 and the high-voltage discharge circuit 3 to complete their work.

[0058] The present invention provides a neutron control circuit 5, including a high-voltage sampling circuit 1, a single-chip microcomputer U1, and a driving isolation circuit U2. The single-chip microcomputer U1 can control the operation of the high-voltage oscillation circuit 4 and the high-voltage discharge circuit 3 according to the received trigger pulse and the first voltage signal, so as to control the generation and discharge of DC high voltage and achieve the effect of neutron control; the single-chip microcomputer U1 replaces multiple modules such as the trigger pulse shaping drive, oscillation circuit, oscillation control circuit, comparison circuit, switch circuit, and monostable narrow pulse circuit in the prior art, and the driving isolation circuit U2 replaces the oscillation drive circuit and the driving isolation circuit in the prior art, making the circuit design simple, reducing the volume of the entire control circuit, making the circuit clear and distinct, greatly reducing the components required for circuit design, having a high degree of integration, and being easy to judge faults and repair; after the high-voltage discharge circuit 3 stops working, the single-chip microcomputer U1 will output a second control signal to control the operation of the high-voltage oscillation circuit 4, ensuring that the high-voltage discharge circuit 3 and the high-voltage oscillation circuit 4 do not work simultaneously, avoiding risk situations such as large working current caused by simultaneous charging and discharging, improving the accuracy and reliability in the application process of the neutron source, and expanding the application range of the neutron source.

[0059] Based on the above embodiments, please refer to Figure 3 , Figure 3 which is a schematic structural diagram of a neutron control device provided by the present invention; please refer to Figure 4 , Figure 4 which is a schematic structural diagram of another neutron control device provided by the present invention.

[0060] As a preferred embodiment, the high-voltage discharge circuit 3 stops working, including:

[0061] After the first control signal outputs a first preset time period, it is determined that the high-voltage discharge circuit 3 stops working.

[0062] It can be understood that the single-chip microcomputer U1 can determine whether the high-voltage discharge circuit 3 stops working through a timer. A delay of a first preset time period can be performed after the first control signal is output. After the first control signal is output for the first preset time period, that is, after the high-voltage discharge circuit 3 has worked for the first preset time period, it is determined that the high-voltage discharge circuit 3 has completed discharging and can stop working. The specific value of the first preset time period, etc., depends on the specific value of the high voltage and the internal structure of the high-voltage discharge circuit 3, and can be adjusted according to different situations in actual applications. The higher the high voltage generated by the high-voltage generation circuit 2, the longer the time required for the high-voltage discharge circuit 3 to stop working. The internal structure of the high-voltage discharge circuit 3 will affect the speed of the discharge process and also affect the value of the first preset time period.

[0063] In actual applications, the single-chip microcomputer U1 can also determine whether the high-voltage discharge circuit 3 stops working by detecting voltage and / or current. A detection module can be set to detect the voltage and / or current at the output end of the high-voltage discharge current. When the voltage and / or current at the output end of the high-voltage discharge current approaches zero and basically remains at zero, it can also be determined that the high-voltage discharge circuit 3 has completed discharging and can stop working. The specific implementation method of the single-chip microcomputer U1 for determining whether the high-voltage discharge circuit 3 stops working is not particularly limited in this application.

[0064] Specifically, the single-chip microcomputer U1 can use a timer to determine whether the high-voltage discharge circuit 3 stops working. After the first control signal is output for the first preset time period, it is determined that the high-voltage discharge circuit 3 stops working. The determination method is simple and accurate. The method of timer determination and control improves the accuracy of the entire control process, facilitates the process of the control program, and ensures the accuracy and reliability of the entire control circuit.

[0065] As a preferred embodiment, the high-voltage sampling circuit 1 includes a first voltage-dividing resistor and a second voltage-dividing resistor. The first end of the first voltage-dividing resistor is grounded, and the second end is connected to the first end of the second voltage-dividing resistor and the second input end of the single-chip microcomputer U1 respectively. The second end of the second voltage-dividing resistor is connected to the output end of the high-voltage generation circuit 2.

[0066] Specifically, the high-voltage sampling circuit 1 can be implemented through a voltage-dividing circuit. The specific type, parameter value, and specific implementation method of the first voltage-dividing resistor and the second voltage-dividing resistor are not particularly limited in this application and can be adjusted according to actual application situations. The first voltage-dividing resistor and the second voltage-dividing resistor can both use fixed resistors, or can selectively use variable resistors, etc. The first voltage-dividing resistor and / or the second voltage-dividing resistor can be realized by the series-parallel connection of multiple resistors. In order to ensure the accurate and stable working process of the voltage-dividing circuit, voltage stabilizing diodes or other voltage stabilizing devices or circuits can also be connected in parallel at both ends of the first voltage-dividing resistor and / or the second voltage-dividing resistor.

[0067] As a specific embodiment, as Figure 4 shown, the high-voltage sampling circuit 1 is composed of a resistor R1, a resistor R2, a potentiometer W1 and a voltage-regulating diode Z2. The resistor R1 and the resistor R2 serve as the second voltage-dividing resistors, and the potentiometer W1 serves as the first voltage-dividing resistor. The entire circuit serves as a resistor voltage-dividing circuit for 3000V DC high voltage, and its voltage-dividing output is sent to the AD port of the single-chip microcomputer U1. The relationship between the sampled voltage and the DC high voltage is as follows: VSAM = VHV * W1 / (R1 + R2 + W1); where VSAM is the output voltage of the high-voltage sampling circuit 1, in volts (V), VHV is the 3000V DC high voltage, in volts (V), W1 is an adjustable potentiometer with a size of 10K and a surface-mount 3224 package, and the sizes of R1 and R2 are both 3.3M with a power of 3 watts and an AXIAL0.5 package. Z2 is a 5V voltage-regulating diode with a 1 / 2W surface-mount package, and its purpose is to limit the sampled input voltage to no more than 5V to protect the AD input port of the single-chip microcomputer U1. By adjusting the potentiometer W1, the magnitude of the DC high-voltage output can be adjusted. It can be set that when the sampled voltage is 3V, it represents a DC high voltage of 3000V. The specific setting of the sampled voltage magnitude can be selected and adjusted according to the internal program of the single-chip microcomputer U1 and the specific value of the high voltage. The specific numerical setting of the voltage division and so on are not particularly limited in this application.

[0068] Specifically, the high-voltage sampling circuit 1 can be implemented through a voltage-dividing circuit. The second end of the first voltage-dividing resistor is connected to the second input end of the single-chip microcomputer U1, and the voltage-divided sampled voltage is output to the single-chip microcomputer U1, so that the single-chip microcomputer U1 can monitor the voltage output by the high-voltage generating circuit 2 in real time through the sampled voltage, ensuring that the single-chip microcomputer U1 can adjust the control process according to different situations of the voltage output by the high-voltage generating circuit 2. The circuit is simple and effective, easy to implement, and conducive to the accurate implementation of the entire control circuit.

[0069] As a preferred embodiment, the high-voltage oscillation circuit 4 includes a first switch G1, a transformer T1, an oscillation resistor R7, a first oscillation capacitor E1 and a second oscillation capacitor E2; the control end of the first switch G1 is connected to the output end of the drive isolation circuit U2, the first end is grounded, and the second end is connected to the first end of the primary winding of the transformer T1. The second end of the primary winding of the transformer T1 is respectively connected to the first end of the oscillation resistor R7 and the first end of the second oscillation capacitor E2. The second end of the oscillation resistor R7 is connected to the power supply, and the second end of the second oscillation capacitor E2 is connected to the first end of the first oscillation capacitor E1. The second end of the first oscillation capacitor E1 is grounded;

[0070] The first switch G1 is used to conduct when the single-chip microcomputer U1 outputs a second control signal, so that the high-voltage generating circuit 2 works; when the single-chip microcomputer U1 does not output a second control signal, it is turned off, so that the high-voltage generating circuit 2 stops working.

[0071] It can be understood that the control of the high-voltage oscillation circuit 4 over the high-voltage generation circuit 2 can be achieved by setting the first switch G1. When the first switch G1 is turned on, the high-voltage oscillation circuit 4 operates, outputting an oscillation signal to control the operation of the high-voltage generation circuit 2. When the first switch G1 is turned off, the high-voltage oscillation circuit 4 does not operate and will not output an oscillation signal to control the high-voltage generation circuit 2 to stop working. Therefore, the single-chip microcomputer U1 can control the high-voltage oscillation circuit 4 and the high-voltage generation circuit 2 by controlling the on and off of the first switch G1. The specific type and implementation method of the first switch G1 are not particularly limited in this application. There are also various implementation methods for the specific processing of the drive isolation of the oscillation signal, which are not particularly limited in this application and can be achieved through the cooperation of the transformer T1, the oscillation resistor R7, the first oscillation capacitor E1, and the second oscillation capacitor E2.

[0072] As a specific embodiment, as Figure 4 shown, the high-voltage oscillation circuit 4 is composed of an oscillation resistor R7, a current-limiting resistor R5, a first oscillation capacitor E1, a second oscillation capacitor E2, an N-channel MOS transistor G1, and a transformer T1. The PWM signal with driving ability from the drive isolation circuit U2 is connected to the gate of the N-channel MOS transistor through the current-limiting resistor R5. The 150V bus voltage is connected to one end of the primary of the transformer T1 through the oscillation resistor R7, and the other end of the primary is connected to the drain of the MOS transistor. The source of the MOS transistor is grounded. The function of the current-limiting resistor R5 is current-limiting protection, with a resistance value of 100 ohms and a 0805 SMD package. The functions of the oscillation resistor R7, the first oscillation capacitor E1, and the second oscillation capacitor E2 are to isolate the oscillation between the 150V bus voltage and the transformer T1. The resistance value of the oscillation resistor R7 is 110 ohms and the power is 10W. The capacitance values of the first oscillation capacitor E1 and the second oscillation capacitor E2 are 150 μF, and high-temperature tantalum capacitors with a withstand voltage of 150V are selected. The power of the transformer T1 is 30W, the turns ratio of the primary to the secondary is 1:4, the number of turns of the primary is 150 turns, and the number of turns of the secondary is 600 turns. The MOS transistor selected is an N-channel MOS transistor 2SK1544 with a withstand voltage of 500V and a current of 30A, and the package is TO-3PL.

[0073] Specifically, the high-voltage oscillation circuit 4 includes a first switch G1, a transformer T1, an oscillation resistor R7, a first oscillation capacitor E1, and a second oscillation capacitor E2. The control of the high-voltage generation circuit 2 is achieved by the on or off of the first switch G1, and the drive isolation of the oscillation signal is realized through the cooperation of the transformer T1, the oscillation resistor R7, the first oscillation capacitor E1, and the second oscillation capacitor E2. It effectively realizes the control of the high-voltage generation circuit 2 by the high-voltage oscillation circuit 4 based on the control signal of the single-chip microcomputer U1. The circuit is simple and effective, easy to implement, and ensures the reliable control of the control circuit over the high-voltage generation circuit 2.

[0074] As a preferred embodiment, the single-chip microcomputer U1 is further configured to,

[0075] after detecting a trigger pulse, determine whether a trigger pulse is detected again within a second preset time period;

[0076] if so, return to the step of outputting a first control signal to control the high-voltage discharge circuit 3 to operate;

[0077] if not, stop working.

[0078] Considering that in the case of not receiving a trigger pulse for a long time, the single-chip microcomputer U1 and the entire control circuit can directly exit the working state of the target shooting mode. Therefore, a timing program can be set to detect the time period after receiving a trigger pulse. After detecting a trigger pulse, it is determined whether a trigger pulse is detected again within a second preset time period. If so, it proves that there is still a trigger pulse, and the single-chip microcomputer U1 and the entire control circuit need to continue to work in the target shooting mode to control the neutron generation process. If not, it proves that there is no trigger pulse at this time and there is no need to control the neutron generation, and the work can be stopped to exit the target shooting mode; the specific value and setting method of the second preset time period are not particularly limited in this application.

[0079] Generally, the sending interval of the trigger pulse is about 75 milliseconds. When setting a timer to detect the time period after receiving a trigger pulse, a timing flag of 80 milliseconds can be set. When no trigger pulse is received within a time greater than 80 milliseconds after the control circuit receives a trigger pulse, the single-chip microcomputer U1 outputs a low level to control the high-voltage oscillation circuit 4 to stop working, and the entire control circuit exits the target shooting mode.

[0080] Specifically, by adding multiple detections of the trigger pulse to regulate the entire control process of the control circuit, it is determined whether the current circuit needs to continue to work in the target shooting mode. If the trigger pulse has stopped being sent, the entire control circuit can exit the target shooting mode to reduce power consumption, and re-enter the target shooting mode after receiving a trigger pulse again, reducing the power consumption of the entire control circuit, increasing the lifespan of the entire control circuit, and expanding the application range of the control circuit.

[0081] As a preferred embodiment, detecting a first voltage signal to determine whether to stop outputting a second control signal based on the first voltage signal and a preset voltage threshold includes:

[0082] Receiving and detecting the first voltage signal;

[0083] Determining whether the first voltage signal is greater than the preset voltage threshold;

[0084] If so, stop outputting the second control signal to control the high-voltage oscillation circuit 4 to stop working;

[0085] If not, continue to output the second control signal and return to the step of receiving and detecting the first voltage signal.

[0086] Considering that when the voltage output by the high-voltage generation circuit 2 meets the requirements, the voltage generation can be stopped. Therefore, the single-chip microcomputer U1 monitors the voltage output by the high-voltage generation circuit 2 through the first voltage signal output by the high-voltage sampling circuit 1 and the preset voltage threshold set in advance. When the first voltage signal is greater than the preset voltage threshold, at this time, the high-voltage generation circuit 2 has generated sufficient required high voltage, and there is no need to continue the voltage generation process. The single-chip microcomputer U1 can stop outputting the second control signal to control the high-voltage oscillation circuit 4 to stop working, so as to control the high-voltage generation circuit 2 to stop generating voltage; when the first voltage signal is less than the preset voltage threshold, at this time, the high-voltage generation circuit 2 has not generated sufficient required high voltage, and the voltage generation process needs to continue. The single-chip microcomputer U1 needs to continue to output the second control signal to control the high-voltage oscillation circuit 4 to work and monitor the situation of the first voltage signal in real time until the voltage output by the high-voltage generation circuit 2 meets the requirements and the first voltage signal is greater than the preset voltage threshold, then the single-chip microcomputer U1 can stop outputting the second control signal.

[0087] In practical applications, the voltage output by the high-voltage generation circuit 2 may not always be in a stable state. The preset voltage threshold can be set as an interval value, and the high-voltage generation circuit 2 can be controlled to stop working when the voltage output by the high-voltage generation circuit 2 is generally maintained near the target value. The specific type and value of the preset voltage threshold are not particularly limited in this application and can be selected according to different requirements for high voltage in practical applications.

[0088] Specifically, the single-chip microcomputer U1 determines whether the voltage output by the high-voltage generation circuit 2 meets the requirements by judging the magnitude relationship between the first voltage signal and the preset voltage threshold, so as to achieve accurate control of the high-voltage generation circuit 2, ensure that the high-voltage generation circuit 2 generates sufficient required high voltage, and at the same time avoid damage to devices caused by outputting too high voltage, improving the accuracy and reliability of the entire control circuit.

[0089] As a preferred embodiment, it further includes:

[0090] A protection circuit 21, the input end of the protection circuit 21 is connected to a trigger pulse, and the output end is connected to the first input end of the single-chip microcomputer U1.

[0091] Considering that when the trigger pulse is input to the pin of the single-chip microcomputer U1, there may be impacts caused by excessive voltage or other situations, resulting in pin damage or other problems. A protection circuit 21 is added between the trigger pulse and the second input terminal of the single-chip microcomputer U1 to protect the pins of the second input terminal of the single-chip microcomputer U1. The specific implementation method of the protection circuit 21 is not particularly limited in this application and can be implemented through a voltage-dividing circuit or a voltage-stabilizing module Z1, etc.

[0092] Specifically, in order to further protect the pins of the single-chip microcomputer U1, a protection circuit 21 is added between the trigger pulse and the second input terminal of the single-chip microcomputer U1 to avoid pin damage and other situations caused by trigger pulse overshoot, reduce the limiting conditions for the trigger pulse, further ensure the safety of the single-chip microcomputer U1, improve the service life of the entire control circuit, and expand the application range of the control circuit.

[0093] As a preferred embodiment, the protection circuit 21 includes a protection resistor R4 and a voltage-stabilizing module Z1; the first end of the protection resistor R4 is connected to the trigger pulse, the second end is respectively connected to the first end of the voltage-stabilizing module Z1 and the first input terminal of the single-chip microcomputer U1, and the second end of the voltage-stabilizing module Z1 is grounded.

[0094] It can be understood that the protection circuit 21 can be implemented by a voltage-dividing circuit composed of the protection resistor R4 and the voltage-stabilizing module Z1. The specific type and implementation method of the voltage-stabilizing module Z1 are not particularly limited in this application and can be implemented by devices such as a voltage-stabilizing diode; the specific type and parameter values of the protection resistor R4 are not particularly limited in this application and can be implemented by a fixed resistor or a variable resistor, etc.

[0095] As a specific embodiment, please refer to Figure 4 , the protection circuit 21 is composed of a protection resistor R4 and a voltage-stabilizing diode Z1. When the external trigger pulse is greater than 5V and the single-chip microcomputer U1 is powered by 5V, the external trigger pulse is changed into a pulse that cannot be higher than 5V to protect the IO port of the single-chip microcomputer U1 and ensure that the trigger pulse can be reliably sent to the interrupt port INT of the single-chip microcomputer U1. The protection resistor R4 uses a 0805 package with a resistance value of 1K, and the voltage-stabilizing diode uses a 5.1V, 1 / 2W surface-mount package.

[0096] Specifically, the protection circuit 21 is implemented by a voltage-dividing circuit composed of the protection resistor R4 and the voltage-stabilizing module Z1. The circuit is simple and effective, can effectively protect the pins of the single-chip microcomputer U1, is easy to implement, and is convenient for the application and popularization of the entire control circuit.

[0097] As a specific embodiment, please refer to Figure 4 , the trigger pulse can be connected to the external interrupt port INT of the single-chip microcomputer U1, that is Figure 3Pin 5 (RA2) of the microcontroller U1 shown is selected by software to have its multiplexed function as an external interrupt. The analog voltage value from the high-voltage sampling circuit 1 is fed into pin 2 (RA0) of the microcontroller U1, and its multiplexed function is selected by software for AD acquisition. The PWM signal is output from pin 7 (RA5) of the microcontroller U1, and its multiplexed function is selected by software for PWM function. The narrow pulse signal is output from pin 3 (RA4) of the microcontroller U1, and its function is selected by software as a port output.

[0098] Considering that in the prior art, the amplitude of the trigger pulse at point A is about 9V, the period is 75 milliseconds, and the pulse width is in microseconds. In the target shooting mode, point A receives the target shooting trigger pulse, and its waveform is as Figure 6 shown. After passing through the shaping and driving circuit, since most of the control circuits are CMOS devices and powered by 12V, the waveform at point O can be the expansion of a single waveform at point A, becoming close to 11V, with the pulse width unchanged, still 30 microseconds, and the period 75 milliseconds. In order to meet the requirements of the high-voltage oscillation circuit 4 for the control waveform in the target shooting mode, in this embodiment, a PWM wave is used as the second control signal to achieve the control requirements for the high-voltage oscillation circuit 4. And when there is a trigger pulse at point O, point O will output to the monostable narrow pulse circuit, and the waveform output by the monostable narrow pulse circuit is as Figure 8 shown, with a high-level pulse width of about 680 nanoseconds, an amplitude of about 11V, and the period unchanged, still 75 milliseconds. In this embodiment, a narrow pulse signal is used as the first control signal to achieve the control requirements for the high-voltage discharge circuit 3. The present invention utilizes the microcontroller U1 and new circuit components, and uses a software control method to replace the complex hardware control circuit, designing a new control circuit for DC high-voltage generation and discharge, which is simple and clear, with fewer circuit components, reducing faults and facilitating maintenance.

[0099] Specifically, please refer to Figure 5 , Figure 5 which is a schematic flow chart of the control process of a neutron control circuit provided by the present invention; the program flow chart of the microcontroller U1 is as Figure 5 shown. First, the initialization of the main program is performed, the pin functions are set, the oscillation clock selects the internal 32M clock oscillation, pin RA2 is selected as the interrupt input function, pin RA0 is selected as the AD conversion function, the AD conversion clock is selected as FOSC / 2, the reference voltage is 5V, pin RA5 is selected as the PWM function, the PWM period is set to 50 microseconds, that is, the frequency is 20K, the duty cycle is 50%, the timer 1 is selected as a 16-bit timer, and the timing is set to 80 milliseconds. The 80-millisecond timing flag is set, the PWM output flag is cleared to ensure that there is no high voltage at the initial working time, the timer 1 interrupt is opened, the INT interrupt is opened, and the total interrupt is opened.

[0100] After initialization is completed, the main program will check the PWM output flag. If it is zero, it will loop and check; if it is set, PWM output is allowed, which means allowing the generation of 3000V high voltage. Then, it starts the AD conversion downward and determines whether the AD value is greater than 3V. If it is less than 3V, it will loop to collect the AD value. When the software makes a judgment, the sampling voltage of 3V corresponds to the high voltage of 3000V. When the sampling voltage is greater than or equal to 3V, PWM output is prohibited, the PWM output flag is cleared, and the DC high voltage will not rise. At this time, it checks the flag for a timing of 80 milliseconds. If the timing flag is set, it will re-check the PWM output flag and re-enter the main program flow; if the timing flag is not set, it will re-loop the determination process of DC high voltage sampling to ensure that no DC high voltage is generated when there is no trigger pulse for more than 80 milliseconds.

[0101] Outside the main program, in order to ensure that the high-voltage oscillation circuit 4 and the high-voltage discharge circuit 3 do not work simultaneously, an interrupt service program is also set up. The interrupt entry is determined according to the interrupt flag. The trigger pulse is connected to the interrupt INT port. When the interrupt trigger pulse INT comes, it first enters the INT interrupt service program. The interrupt service program first prohibits PWM output to avoid the operation of the high-voltage oscillation circuit 4, and then sends out a narrow pulse of 5 instruction cycles from the IO port RA4. The period of the narrow pulse signal can be set to a single 125 nanoseconds, with a total of 625 nanoseconds, and then it delays for 10 microseconds. It sets the PWM output allowed flag, that is, it allows the output of the second control signal only after ensuring that the high-voltage discharge circuit 3 stops working, and then clears the timer 1 and the 80-millisecond flag to make the timing start again. When the timer 1 interrupt comes, it enters the timer interrupt service program to determine whether 80 milliseconds have passed. If not, the interrupt returns. If the time has passed, it prohibits PWM output, clears the PWM output allowed flag, sets the 80-millisecond flag, and the interrupt returns. That is, when there is no interrupt pulse for a long time, no high voltage is generated, and the control circuit exits the firing mode.

[0102] As a specific embodiment, as Figure 4 shown in the neutron control circuit 5, the single-chip microcomputer U1 uses an 8-pin SO-8 surface-mounted PIC single-chip microcomputer with 8-bit high-speed nanosecond-level. The single-chip microcomputer U1 has an external input pulse interrupt function, an AD function, and a PWM function. By using the method of software control of the single-chip microcomputer U1, it can output nanosecond-level narrow pulses when there is a trigger pulse, and at the same time realize high-voltage AD sampling comparison. By controlling the generation of PWM pulses with a frequency of 20K Hertz and a duty cycle of 50%, it controls the generation and discharge of 3000 DC high voltage. The drive isolation circuit U2 uses an integrated chip U2, and U2 is selected as TC4427, which is a dual-high-speed power MOSFET driver with a driving ability of 1.5A, in a surface-mounted SO-8 package, and the driving power supply can reach 18V, replacing the original drive circuit, with a small volume, a simple and clear circuit, and a large driving ability.

[0103] The neutron control circuit 5 provided by this application replaces the complex hardware functions in the prior art with software functions, including an oscillation circuit, a voltage comparison circuit, a switching circuit, an oscillation control circuit, and a monostable narrow pulse circuit. The single-chip microcomputer U1 can use an 8-pin surface-mount PIC single-chip microcomputer with 8-bit high-speed nanosecond-level performance. The drive isolation circuit U2 can use a dual high-speed power MOSFET driver with a driving capacity of 1.5 A, surface-mount SO-8 package TC4427, to replace the oscillation drive circuit and the narrow pulse drive isolation circuit U2. This makes the circuit design simple, with fewer components, smaller size, and a clear circuit, facilitating use and maintenance. The entire control process adopts the method of software control by the single-chip microcomputer U1. When a trigger pulse interruption is received, a narrow pulse is first sent to control the DC high-voltage discharge. The electricity of the DC high voltage is the electricity stored in the capacitor of the DC high-voltage circuit. After a delay of 10 microseconds, the high-voltage oscillation circuit 4 is allowed to work to charge the capacitor, avoiding the logical conflict of large working current caused by the possible simultaneous operation of charging and discharging.

[0104] To solve the above technical problems, the present invention also provides a neutron control device 31, including a high-voltage oscillation circuit 4, a high-voltage generation circuit 2, a high-voltage discharge circuit 3, and the neutron control circuit 5 as described above;

[0105] The output end of the high-voltage oscillation circuit 4 is connected to the input end of the high-voltage generation circuit 2. The output end of the high-voltage generation circuit 2 is respectively connected to the first input end of the neutron control circuit 5, the first input end of the high-voltage discharge circuit 3, and the input end of the neutron generator 32. The output end of the neutron control circuit 5 is respectively connected to the input end of the high-voltage oscillation circuit 4 and the second input end of the high-voltage discharge circuit 3.

[0106] It can be understood that for the specific circuit structures and implementation manners of the high-voltage oscillation circuit 4, the high-voltage generation circuit 2, and the high-voltage discharge circuit 3, this application does not make special limitations here, and they can be selected and adjusted according to actual application requirements.

[0107] As a specific embodiment, please refer to Figure 4 , the high-voltage generation circuit 2 is composed of capacitors C6, C7, C8, C9, C10, C11, and diodes D2, D3, D4, D5, D6, D7. This is a 6-fold voltage multiplier circuit. The diodes are selected as high-voltage silicon stacks with a breakdown voltage of 10 KV, and the package size is AXIAL0.4. The capacitors are selected as high-temperature capacitors with a capacitance value of 0.01 UF and a breakdown voltage of 3 KV, and the package is RAD0.3. One path of the high-voltage output is connected to the high-voltage sampling circuit 1, one path is connected to the 3000V pulsed high-voltage discharge circuit 3, and one path is connected to the PNN neutron generator 32.

[0108] The high-voltage discharge circuit 3 consists of a resistor R6, MOS transistors G2, G8, G9, G10, a transformer T2, and voltage-regulating diodes Z1, Z2, Z3, Z4, Z5, Z6. The function of R6 is current-limiting protection. Its resistance value is 100 ohms, and it is in 0805 SMD package. The voltage-regulating diodes also play a protective role. SMD voltage-regulating diodes with a regulated voltage of 15V and a power of 1W can be selected. G2 can be an N-channel high-frequency MOS transistor 2N7002 in TO-92 package. Its input capacitance is 50PF, output capacitance is 25PF. It has less turn-on and turn-off delay and fast switching speed, enabling rapid opening and cutoff of pulse signals, forming a narrow pulse of about 1 microsecond, and avoiding over-wide high-voltage pulse signals that may lead to large currents. G8, G9, and G10 are N-channel MOS transistors IHW30N160R2 with a breakdown voltage of 1600V and a current of 30A in TO-247 package. The transformer T2 has one primary winding with a breakdown voltage of 30V and three secondary windings, each with a breakdown voltage of 30V. When there is no pulse in the primary, the three MOS transistors are cutoff. When there is a pulse, G8, G9, and G10 conduct simultaneously, and the DC high voltage discharges to the ground through the series connection of the three MOS transistors, forming the high-voltage negative pulse required for the operation of the PNN neutron generator 32. The same-end connection of the transformer T1 should be consistent to ensure that the three transistors turn on simultaneously when a pulse arrives.

[0109] In this application, the N-channel high-frequency MOS transistor 2N7002 is selected as the switching transistor in the high-voltage discharge circuit. Its input capacitance is 50PF and output capacitance is 25PF. The originally selected MOS transistor was IRF420, with an input capacitance of 300PF and an output capacitance of 75PF. The narrow pulse was wide, generally 2 to 3 microseconds. The N-channel high-frequency MOS transistor 2N7002 in TO-92 package is selected for the oscillation of the transformer T1 in the discharge circuit. With less input and output capacitance, it can have less turn-on and turn-off delay and fast switching speed, enabling rapid opening and cutoff of pulse signals, forming a narrow pulse of about 1 microsecond without tailing, and avoiding over-wide high-voltage pulse signals that may lead to large currents.

[0110] It can be understood that, as Figure 1 and Figure 3 shown, Figure 1 in the prior art shown at points O, H, F, C, G, and P, the signal waveforms are the same as Figure 3The signal waveforms of points O, H, F, C, G, and P shown can be approximately the same in practical applications, and the output signals corresponding to the same labeled points have the same functions; the signal at point O is the processed trigger pulse so that the single-chip microcomputer U1 can accurately and effectively detect the trigger pulse; the signal at point H is the sampled voltage signal corresponding to the voltage sampled from the output of the high-voltage generation circuit 2; the signal at point F is the control signal for controlling the operation of the high-voltage oscillation circuit 4; the signal at point C is the control signal for controlling the operation of the high-voltage discharge circuit 3; the signal at point G is the output signal after enhancing the driving ability of the signal at point F; the signal P is the output signal after enhancing the driving ability of the signal at point C. The signal at point B in the prior art is the oscillation control signal output by the switching circuit in response to the trigger pulse signal; the signal at point E is the oscillation signal output by the oscillation circuit; the signal at point D is the comparison result output by the comparison circuit. Thus, it can be seen that the control process of the neutron control circuit 5 provided by the present application reduces the signal conversion process and improves the response speed and working efficiency.

[0111] Please refer to Figure 6 , Figure 6 which is a schematic diagram of the signal waveform of a trigger pulse provided by the present invention; please refer to Figure 7 , Figure 7 which is a schematic diagram of the waveform of a control signal provided by the prior art; Figure 7 shown is a schematic diagram of the signal waveform output by the trigger pulse shaping and driving circuit after processing the trigger pulse; please refer to Figure 8 , Figure 8 which is another schematic diagram of the waveform of a control signal provided by the prior art; Figure 8 shown is a schematic diagram of the signal waveform output by the monostable narrow pulse circuit; please refer to Figure 9 , Figure 9 which is a schematic diagram of the waveform comparison of a control signal provided by the prior art; please refer to Figure 10 , Figure 10 which is another schematic diagram of the waveform comparison of a control signal provided by the prior art. Specifically, the single-chip microcomputer U1 outputs a square wave with a duty cycle of 50%, a frequency of 20K, and an amplitude of about 11V. After passing through the drive isolation circuit U2, the finally output waveform with driving ability is as shown by waveform B in Figure 9 , Figure 9 which is a comparison diagram of the waveform output by the drive isolation circuit U2 and the waveform of the trigger pulse. Waveform A is the schematic diagram of the waveform of the trigger pulse, and waveform B is the schematic diagram of the waveform of the signal output by the drive isolation circuit U2. When a trigger pulse is input, the high-voltage discharge circuit 3 will quickly reduce the 3000V DC high voltage. At this time, the control circuit outputs a second control signal to allow the oscillation output, and the waveform output by the drive isolation circuit U2 is as shown by Figure 9The shaded part of the waveform shown is a 20K square wave oscillation. When the DC high voltage reaches 3000V, there is no oscillation output, which is the blank space between the shaded part and the next trigger pulse. Figure 10 It is a comparison schematic diagram of the waveform of the output signal of the high-voltage sampling circuit 1 and the waveform output by the drive isolation circuit U2. When the trigger pulse arrives, the single-chip microcomputer U1 will generate a narrow pulse of 1-3 microseconds to discharge the 3000V DC high voltage. The high-voltage output is quickly pulled down. After the high-voltage output is pulled down, the high-voltage oscillation circuit 4 works. As time increases, the voltage output by the high-voltage generation circuit 2 gradually increases, and the voltage output by the high-voltage sampling circuit 1 also gradually increases. When the voltage output by the high-voltage generation circuit 2 reaches the preset high voltage of 3000V, the high-voltage oscillation circuit 4 stops working, and the voltage output by the high-voltage sampling circuit 1 also stops increasing. The high-voltage waveform is Figure 10 as shown.

[0112] For the introduction of a neutron control device 31 provided by the present invention, please refer to the embodiment of the neutron control circuit 5 described above, and this application will not elaborate here.

[0113] Please refer to Figure 11 , Figure 11 which is a schematic structural diagram of a neutron control system provided by the present invention. To solve the above technical problems, the present invention also provides a neutron control system, including a neutron generator 32 and the aforementioned neutron control device 31, and the neutron generator 32 is connected to the neutron control device 31.

[0114] For the specific type and implementation manner of the neutron generator 32, etc., this application does not make special limitations here. The neutron generator 32 includes a neutron tube. The neutron generator 32 realizes the neutron generation process by controlling the operation of the neutron tube. For the specific type and implementation manner of the neutron tube, etc., this application does not make special limitations here. The type selection of the neutron generator 32 and the neutron tube can refer to each other and be selected according to the working requirements in actual applications.

[0115] Generally, in the PNN logging process, a PNN neutron generator 32 is adopted. The neutron tube used is usually a low-frequency neutron tube with a relatively high yield of 2×10⁸ neutrons per second. Its working mode is generally that each emission time is 1 to 3 μs, then there is an interval of 30 μs, and then 1800 μs is recorded. Each emission acquisition cycle is 75 ms, so it emits 13 to 14 times per second. Because of the relatively high neutron yield, it ensures that a relatively high counting rate can still be obtained at this emission frequency, reduces the usage time of the neutron tube, and increases its service life. The outer diameter of the PNN instrument is 43 mm and it is powered by single-core DC. Due to space limitations in downhole instrument design, generally, the smaller the current, the better, and the fewer and smaller the components, the smaller the circuit board size, and the shorter the instrument, the better. The existing PNN circuit design has limitations due to the design at that time, with disadvantages such as many components, large component volumes, and complex control. The neutron control system provided by this application can solve the above problems. The circuit design is simple, reducing the volume of the entire control circuit. The circuit is clear and distinct, greatly reducing the components required for circuit design, with high integration, and being easy to judge faults and repair.

[0116] It is not difficult to understand that the neutron control circuit 5 controls the operation of the PNN neutron generator 32 by controlling the 3000V DC high voltage sent to the PNN neutron generator 32. When there is no trigger pulse, no DC high voltage is generated, and the 3000V DC high voltage is at zero level. When a trigger pulse is sent, the 3000V DC high voltage discharges rapidly, generating a negative pulse of 3000V to control the operation of the neutron generator 32.

[0117] For the introduction of a neutron control system provided by the present invention, please refer to the embodiments of the above-mentioned neutron control circuit 5, and this application will not elaborate here.

[0118] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and reference can be made to the description in the method part for related parts.

[0119] It should also be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0120] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A neutron control circuit, characterized in that: include: A high-voltage sampling circuit, the input end of which is connected to the output end of the high-voltage generating circuit, the output end of which is connected to the first input end of the single-chip microcomputer, and is used to output a first voltage signal to the first input end of the single-chip microcomputer, wherein the first voltage signal is linearly correlated with the voltage output by the high-voltage generating circuit; The single-chip computer has a second input terminal connected to a trigger pulse, and an output terminal connected to an input terminal of a driving isolation circuit, and is used to output a first control signal to control the high-voltage discharge circuit to work when the trigger pulse is detected; after the high-voltage discharge circuit stops working, output a second control signal to control the high-voltage oscillation circuit to work, so as to make the high-voltage generating circuit work; and detect the first voltage signal after outputting the second control signal, so as to determine whether to stop outputting the second control signal based on the first voltage signal and a preset voltage threshold; The output end of the driving isolation circuit is respectively connected to the high-voltage oscillation circuit and the high-voltage discharge circuit.

2. The neutron control circuit according to claim 1, characterized in that: The high-voltage discharge circuit stops working, including: After the first control signal is output for a first preset time period, it is determined that the high-voltage discharge circuit stops working.

3. The neutron control circuit according to claim 1, characterized in that: The high-voltage sampling circuit includes a first voltage-dividing resistor and a second voltage-dividing resistor; the first end of the first voltage-dividing resistor is grounded, and the second end is respectively connected to the first end of the second voltage-dividing resistor and the second input end of the single-chip microcomputer, and the second end of the second voltage-dividing resistor is connected to the output end of the high-voltage generating circuit.

4. The neutron control circuit according to claim 1, characterized in that: The high-voltage oscillation circuit includes a first switch, a transformer, an oscillation resistor, a first oscillation capacitor, and a second oscillation capacitor; the control end of the first switch is connected to the output end of the drive isolation circuit, the first end is grounded, the second end is connected to the first end of the primary winding of the transformer, the second end of the primary winding of the transformer is respectively connected to the first end of the oscillation resistor and the first end of the second oscillation capacitor, the second end of the oscillation resistor is connected to the power supply, the second end of the second oscillation capacitor is connected to the first end of the first oscillation capacitor, and the second end of the first oscillation capacitor is grounded; The first switch is used to be turned on when the single chip microcomputer outputs the second control signal to enable the high voltage generating circuit to work; and to be turned off when the single chip microcomputer does not output the second control signal to enable the high voltage generating circuit to stop working.

5. The neutron control circuit according to claim 1, characterized in that: The single chip microcomputer is also used for: After detecting the trigger pulse, determining whether the trigger pulse is detected again within a second preset time period; If yes, return to the step of outputting the first control signal to control the operation of the high-voltage discharge circuit; If not, stop working.

6. The neutron control circuit according to claim 1, characterized in that: The detecting the first voltage signal to determine whether to stop outputting the second control signal based on the first voltage signal and a preset voltage threshold comprises: receiving and detecting the first voltage signal; Determining whether the first voltage signal is greater than the preset voltage threshold; If yes, stop outputting the second control signal to control the high-voltage oscillation circuit to stop working; If not, continue to output the second control signal and return to the step of receiving and detecting the first voltage signal.

7. The neutron control circuit according to any one of claims 1 to 6, characterized in that: Also includes: A protection circuit, wherein the input end of the protection circuit is connected to a trigger pulse, and the output end is connected to the first input end of the single chip microcomputer.

8. The neutron control circuit according to claim 7, characterized in that: The protection circuit includes a protection resistor and a voltage stabilizing module; the first end of the protection resistor is connected to the trigger pulse, the second end is respectively connected to the first end of the voltage stabilizing module and the first input end of the single chip microcomputer, and the second end of the voltage stabilizing module is grounded.

9. A neutron control device, characterized in that: It comprises a high voltage oscillation circuit, a high voltage generation circuit, a high voltage discharge circuit and a neutron control circuit as claimed in any one of claims 1 to 8; The output end of the high-voltage oscillation circuit is connected to the input end of the high-voltage generating circuit, and the output end of the high-voltage generating circuit is respectively connected to the first input end of the neutron control circuit, the first input end of the high-voltage discharge circuit and the input end of the neutron generator, and the output end of the neutron control circuit is respectively connected to the input end of the high-voltage oscillation circuit and the second input end of the high-voltage discharge circuit.

10. A neutron control system, characterized in that: The invention comprises a neutron generator and the neutron control device as claimed in claim 9, wherein the neutron generator is connected to the neutron control device.

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