Low-latency klystron standing wave protection system and method based on high-speed comparison circuit
By using a low-delay klystron standing wave protection system based on a high-speed comparison circuit, and employing both digital and analog protection paths, ultra-fast fault response and seamless protection across the entire power range of the klystron are achieved. This solves the problems of long delay and blind spots in existing technologies, and improves the operational reliability and fault tolerance of the equipment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI UNIV
- Filing Date
- 2026-02-26
- Publication Date
- 2026-06-09
Smart Images
Figure CN122178239A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of klystron safety protection technology, and more specifically, to a low-delay klystron standing wave protection system and method based on a high-speed comparator circuit. Background Technology
[0002] The klystron is a core high-power microwave amplification device in high-energy physics devices such as free-electron lasers and particle accelerators, operating under extremely high voltage and power conditions. During operation, the klystron is prone to internal mismatch or arcing faults due to factors such as vacuum depletion, gas discharge, and window breakdown. These faults can generate extremely strong transient reflected power in microseconds or even less. If the protection system cannot quickly cut off the input power, it will lead to permanent and catastrophic damage to the klystron. Therefore, the response speed of the protection system is a core indicator of its performance. Currently, there are two main types of klystron protection schemes: Optical protection: Protection is achieved by monitoring the optical signal generated when the klystron output window or waveguide component arcs. The drawback of this method is that when visible arc light is detected, the fault has often already developed to a relatively serious stage, and the equipment may have already been damaged. It is a reactive protection method and cannot achieve early warning and suppression of faults. Reflected power monitoring method: Protection is triggered when the reflected microwave power exceeds a set threshold by monitoring the reflected microwave power through a directional coupler. This method is effective at higher operating power, but when the system starts up or runs at low power, the absolute value of the reflected power is very small, making it difficult to distinguish from system noise. There is a monitoring blind zone, and it cannot effectively identify early impedance mismatch faults at low power.
[0003] Existing systems cannot perform monitoring and protection with low latency and no blind spots, which affects the reliability of equipment operation and makes it difficult to meet the stringent requirements of modern high-precision large scientific facilities for the safe operation of core components. Summary of the Invention
[0004] The present invention aims to solve the problems of existing klystron protection systems being unable to achieve low-latency and blind-zone-free protection, thereby improving the reliability of klystron operation.
[0005] To address the aforementioned problems, this invention provides a low-delay klystron VSWR protection system and method based on a high-speed comparator circuit. The system includes an input terminal of an RF sampling and detection unit connected to a klystron RF output unit; an output terminal of the RF sampling and detection unit communicatively connected to a signal processing and decision-making unit; a signal processing and decision-making unit communicatively connected to a machine interlocking execution unit; a parallel communication connection between the signal processing and decision-making unit and the machine interlocking execution unit via a digital protection signal path and an analog protection signal path; and an output terminal of the machine interlocking execution unit connected to a downstream controlled system.
[0006] The low-delay klystron standing wave protection system and method based on a high-speed comparator circuit provided by this invention has, but is not limited to, the following beneficial effects compared to the prior art: The radio frequency sampling and detection unit of this invention is used to collect the forward and reflected microwave signals from the output of the klystron and convert them into two analog voltage signals; the digital protection path includes an analog-to-digital converter and a signal processor connected in sequence, used to convert the two analog voltage signals into digital signals, and to perform over-limit judgment by calculating the return loss value, generating a first interlocking signal; the machine interlocking execution unit is used to receive the first interlocking signal and the second interlocking signal, and to output a system shutdown command when either signal is valid.
[0007] This invention provides ultra-fast protection by introducing an independent analog protection path based on a high-speed comparator. By utilizing the inherent high-speed characteristics of the hardware circuit, the protection response time for critical faults such as high-power breakdown is compressed to the order of tens of nanoseconds, which greatly curbs the development of the fault and effectively protects the klystron.
[0008] This invention provides full-power range protection without blind spots. It calculates return loss in real time through a digital protection path. This parameter remains sensitive even at low power, successfully solving the monitoring blind spot problem of the traditional absolute value of reflected power monitoring method at low power. It achieves seamless protection across the entire range from startup to full-power operation.
[0009] This invention features dual protection and high reliability. Digital and analog paths operate in parallel, independently and as backups for each other. The digital path offers high accuracy and flexibility, capable of handling complex algorithms; the analog path boasts high speed and reliability. Protection is activated upon triggering of either path, significantly improving the overall reliability and fault tolerance of the system.
[0010] The invention features a flexible and easily integrated architecture. The system architecture is clear, and the analog threshold can be dynamically configured by the digital part, facilitating integration with the upper-level control system and enabling remote and intelligent management of protection thresholds to meet the needs of different operating conditions.
[0011] Furthermore, the RF sampling and detection unit includes a coupling module, an attenuation module, and a detection module, which are connected in series; the input terminal of the coupling module is connected to the klystron RF output unit.
[0012] Furthermore, the signal processing and decision unit is equipped with two sets of digital-to-analog conversion modules, a signal processing and signal discrimination module, and a high-speed comparison module; the first set of digital-to-analog conversion modules is connected to the input end of the signal processing and signal discrimination module, and the output end of the signal processing and signal discrimination module is connected to the high-speed comparison module through the second coarse digital-to-analog conversion module.
[0013] Furthermore, the detection module is connected to the two input terminals of the first set of digital-to-analog converter modules through forward wave analog signals and reflected wave analog signals.
[0014] Furthermore, the detection module is communicatively connected to the input of the high-speed comparison module via a reflected wave analog signal.
[0015] Furthermore, the output of the signal processing and signal identification module is connected to the machine interlocking execution unit via a digital protection signal path.
[0016] Furthermore, the output of the high-speed comparison module is connected to the machine interlocking execution unit via an analog protection signal path.
[0017] The low-delay klystron standing wave protection method based on high-speed comparator circuit includes the following steps: S1. Acquire the forward microwave signal and the reflected microwave signal at the output of the klystron, and convert them into a forward analog voltage signal and a reflected analog voltage signal; S2. Parallel execution of digital protection processing flow and analog protection comparison flow; The digital protection processing flow is to convert the forward analog voltage signal and the reflected analog voltage signal into digital signals, calculate the protection parameters based on the digital signals, and generate the first interlocking signal by comparing the protection parameters with the first protection threshold. The analog protection comparison process involves comparing the reflected analog voltage signal with an analog voltage threshold in real time using hardware to generate a second interlocking signal. S3. Receive the first interlock signal and the second interlock signal, and generate and output a system shutdown command when either signal indicates a fault.
[0018] Furthermore, the calculation of protection parameters based on the digital signal in step S2 specifically involves:
[0019] The two digital signals are filtered; the filtered digital signals are converted into forward power and reflected power values through a lookup table; the difference between the forward power and reflected power values is calculated to obtain the return loss value as the protection parameter.
[0020] Furthermore, the analog voltage threshold in step S2 is dynamically generated by a signal processor based on the system operating status and provided via a digital-to-analog converter; real-time hardware comparison is performed by a high-speed comparator. Attached Figure Description
[0021] Figure 1 A schematic diagram of the fast protection system for a klystron provided in an embodiment of the present invention.
[0022] Figure 2A flowchart illustrating the implementation of a digital protection path in a signal processing and decision-making unit according to an embodiment of the present invention.
[0023] Figure 3 A schematic diagram of an independent simulation protection path provided in an embodiment of the present invention.
[0024] Figure 4 A schematic diagram of the power value mapping principle provided in an embodiment of the present invention. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings showing multiple embodiments according to this application. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.
[0026] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," etc., in the description, claims, and accompanying drawings of this application are open-ended terms. Therefore, "comprising," "including," or "having" refers to, for example, a method or apparatus having one or more steps or elements, but is not limited to having only these one or more elements. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.
[0027] In the description of this invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0028] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0029] It should be emphasized that when the term "comprising / including" is used in this specification, it is used to explicitly indicate the presence of the stated feature, integer, step, or component, but does not exclude the presence or addition of one or more other features, integers, steps, parts, or groups of features, integers, steps, or parts.
[0030] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.
[0031] See Figures 1-4 The low-delay klystron standing wave protection system and method based on a high-speed comparison circuit according to embodiments of the present invention includes an input terminal of an RF sampling and detection unit connected to a klystron RF output unit; an output terminal of the RF sampling and detection unit communicatively connected to a signal processing and decision unit; a signal processing and decision unit communicatively connected to a machine interlocking execution unit; a parallel communication connection between the signal processing and decision unit and the machine interlocking execution unit via a digital protection signal path and an analog protection signal path; and an output terminal of the machine interlocking execution unit connected to a lower-level controlled system.
[0032] The radio frequency sampling and detection unit of this invention is used to collect the forward and reflected microwave signals from the output of the klystron and convert them into two analog voltage signals; the digital protection path includes an analog-to-digital converter and a signal processor connected in sequence, used to convert the two analog voltage signals into digital signals, and to perform over-limit judgment by calculating the return loss value, generating a first interlocking signal; the machine interlocking execution unit is used to receive the first interlocking signal and the second interlocking signal, and to output a system shutdown command when either signal is valid.
[0033] This invention provides ultra-fast protection by introducing an independent analog protection path based on a high-speed comparator. By utilizing the inherent high-speed characteristics of the hardware circuit, the protection response time for critical faults such as high-power breakdown is compressed to the order of tens of nanoseconds, which greatly curbs the development of the fault and effectively protects the klystron.
[0034] This invention provides full-power range protection without blind spots. It calculates return loss in real time through a digital protection path. This parameter remains sensitive even at low power, successfully solving the monitoring blind spot problem of the traditional absolute value of reflected power monitoring method at low power. It achieves seamless protection across the entire range from startup to full-power operation.
[0035] This invention features dual protection and high reliability. Digital and analog paths operate in parallel, independently and as backups for each other. The digital path offers high accuracy and flexibility, capable of handling complex algorithms; the analog path boasts high speed and reliability. Protection is activated upon triggering of either path, significantly improving the overall reliability and fault tolerance of the system.
[0036] The invention features a flexible and easily integrated architecture. The system architecture is clear, and the analog threshold can be dynamically configured by the digital part, facilitating integration with the upper-level control system and enabling remote and intelligent management of protection thresholds to meet the needs of different operating conditions.
[0037] Furthermore, the RF sampling and detection unit includes a coupling module, an attenuation module, and a detection module, which are connected in series; the input terminal of the coupling module is connected to the klystron RF output unit.
[0038] The coupling module of this invention can be applied not only to directional couplers, but also to any device capable of signal coupling, such as branch-line couplers, circulators combined with coupling ports, and even other novel coupling structures that may emerge in the future. As long as it can extract the forward and reflected signals from the main transmission path, it falls within the scope of the coupling module.
[0039] Attenuation modules are not limited to fixed attenuators; they can also include adjustable attenuators, resistor attenuation networks, or any other circuits or components that can attenuate signal amplitude. Detection modules are not limited to "diode detectors"; they can also include transistor-based detection circuits, logarithmic detector amplifiers, or any device that can convert RF power into DC or low-frequency voltage signals.
[0040] Furthermore, the signal processing and decision unit is equipped with two sets of digital-to-analog conversion modules, a signal processing and signal discrimination module, and a high-speed comparison module; the first set of digital-to-analog conversion modules is connected to the input end of the signal processing and signal discrimination module, and the output end of the signal processing and signal discrimination module is connected to the high-speed comparison module through the second coarse digital-to-analog conversion module.
[0041] The analog protection path of this invention includes a digital-to-analog converter and a high-speed comparator. The first input terminal of the high-speed comparator is directly connected to the output terminal of the reflected wave analog voltage signal of the radio frequency sampling and detection unit. The input terminal of the digital-to-analog converter is connected to the signal processor, and the output terminal is connected to the second input terminal of the high-speed comparator. It is used to perform real-time hardware comparison between the reflected wave analog voltage signal and a configurable analog voltage threshold to generate a second interlock signal. Furthermore, the detection module is connected to the two input terminals of the first set of digital-to-analog converter modules through forward wave analog signals and reflected wave analog signals.
[0042] This invention effectively ensures the input of information, facilitates the transmission of communication signals, and makes subsequent work easier.
[0043] Furthermore, the detection module is communicatively connected to the input of the high-speed comparison module via a reflected wave analog signal.
[0044] This invention facilitates the transmission of the reflected wave analog signal to the high-speed comparison module, making subsequent comparison easier and improving the workflow.
[0045] Furthermore, the output of the signal processing and signal identification module is connected to the machine interlocking execution unit via a digital protection signal path.
[0046] This invention illustrates the logical process of digital protection signals flowing from the signal processing module to the interlocking execution unit. It emphasizes the functional path: echoing the previously mentioned analog protection path, it highlights the dual-path architecture of this invention.
[0047] Furthermore, the output of the high-speed comparison module is connected to the machine interlocking execution unit via an analog protection signal path.
[0048] This invention illustrates the logical process of analog protection signals flowing from the high-speed comparison module to the interlocking execution unit. It emphasizes that the functional path echoes the previously mentioned digital protection path, highlighting the dual-path architecture of this invention.
[0049] The low-delay klystron standing wave protection method based on high-speed comparator circuit includes the following steps: S1. Acquire the forward microwave signal and the reflected microwave signal at the output of the klystron, and convert them into a forward analog voltage signal and a reflected analog voltage signal; S2. Parallel execution of digital protection processing flow and analog protection comparison flow; The digital protection processing flow is to convert the forward analog voltage signal and the reflected analog voltage signal into digital signals, calculate the protection parameters based on the digital signals, and generate the first interlocking signal by comparing the protection parameters with the first protection threshold. The analog protection comparison process involves comparing the reflected analog voltage signal with an analog voltage threshold in real time using hardware to generate a second interlocking signal. S3. Receive the first interlock signal and the second interlock signal, and generate and output a system shutdown command when either signal indicates a fault.
[0050] Example 1: A fast protection method for a klystron based on VSWR, based on the above system, includes the following steps: Step 1: Extract the forward and reflected RF signals from the output of the klystron using a directional coupler. After precise attenuation by a fixed attenuator, the signals are converted into two DC analog voltage signals by a diode detector.
[0051] Step 2: The two analog signals are converted into digital signals via an ADC. The FPGA then filters, calibrates, and calculates the VSWR value in real time. The VSWR value is compared with a preset threshold. If it exceeds the threshold, a digital interlocking signal is generated within ≤290ns. The reflected analog signal output from the diode detector is directly sent to a high-speed comparator and compared in real time with an analog threshold set by the FPGA and converted by a DAC. If it exceeds the threshold, an analog interlocking signal is generated within ≤60ns.
[0052] Step 3: Receive the two protection signals mentioned above through the interlocking module, and after judgment by "OR logic", immediately send a shutdown command to all lower-level controlled systems when either path is triggered to achieve rapid protection.
[0053] Example 2: A signal processing flow for a low-delay klystron standing wave ratio (VSWR) protection system based on a high-speed comparator circuit is completed in a signal processor (FPGA). Its core objective is to perform full-process digital processing of the forward and reflected microwave signals from the klystron, achieving real-time, high-precision calculation of the VSWR, and quickly comparing the calculation result with a preset protection threshold, thereby providing high-speed protection for the klystron and downstream RF systems. The specific signal processing steps are as follows: Step 1: The analog-to-digital converter converts the analog voltage signal detected by the diode detector into a digital signal.
[0054] The second step is to perform windowed acquisition on the two digital signals, that is, to synchronously capture digital signal samples of the forward wave and the reflected wave at a preset time interval, forming two sets of parallel digital sequences, which provide time-aligned raw data for subsequent filtering processing.
[0055] The third step is to apply identical low-pass digital filters to the two windowed digital sequences in parallel to remove high-frequency noise. The key is to ensure that the amplitude and phase frequency characteristics of the two filters are consistent to avoid introducing additional errors in subsequent differential calculations.
[0056] Step 4: Receive the two filtered digital voltage signals and convert the digital voltage values into corresponding forward microwave power values (Pf) and reflected microwave power values (Pr) by consulting a pre-stored "digital voltage-microwave power" mapping table (lookup table). This mapping table is generated based on the linear characteristics of the diode detector and system calibration data to ensure the accuracy of power conversion.
[0057] Step 5: To meet the high-speed processing requirements of FPGA and avoid complex VSWR formula calculations, this invention does not directly calculate VSWR, but instead calculates its equivalent parameter—Return Loss (RL).
[0058] The formula for calculating return loss RL is as follows: RL=Pf-Pr Here, Pf and Pr are both in dBm. Since subtraction of the power ratio in the dBm domain is equivalent to division in the linear domain, this calculation can be efficiently implemented in an FPGA using only a single subtractor. There is a unique and fixed mathematical correspondence between return loss and VSWR.
[0059] Step 6: Compare the calculated return loss value with one or more preset protection thresholds in real time. These protection thresholds are pre-calculated and set based on the required VSWR limit and its fixed correspondence with return loss. When the measured return loss value is greater than the threshold, the system is functioning normally; when the measured return loss value is less than the threshold, it indicates that the VSWR has exceeded the threshold, and an interlocking signal is immediately generated.
[0060] Furthermore, the calculation of protection parameters based on the digital signal in step S2 specifically involves:
[0061] The two digital signals are filtered; the filtered digital signals are converted into forward power and reflected power values through a lookup table; the difference between the forward power and reflected power values is calculated to obtain the return loss value as the protection parameter.
[0062] This invention filters two digital signals; converts the filtered digital signals into forward power and reflected power values using a lookup table; calculates the difference between the forward power and reflected power values to obtain the return loss value as the protection parameter.
[0063] Furthermore, the analog voltage threshold in step S2 is dynamically generated by a signal processor based on the system operating status and provided via a digital-to-analog converter; real-time hardware comparison is performed by a high-speed comparator.
[0064] The threshold in this invention is dynamically generated, originating from a digital signal processor. This demonstrates the precise control of analog hardware by digital intelligence. It is not a patchwork of two independent systems, but an organic whole, in which the signal processor sets the threshold for the high-speed comparator in real time.
[0065] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.
Claims
1. A low-delay klystron standing wave protection system based on a high-speed comparator circuit, characterized in that, The radio frequency sampling and detection unit's input is connected to the klystron radio frequency output unit; the radio frequency sampling and detection unit's output is connected to the signal processing and decision unit; the signal processing and decision unit is connected to the machine interlocking execution unit; the signal processing and decision unit and the machine interlocking execution unit are connected through parallel communication via digital protection signal paths and analog protection signal paths; and the machine interlocking execution unit's output is connected to the lower-level controlled system.
2. The low-delay klystron standing wave protection system based on a high-speed comparator circuit according to claim 1, characterized in that, The radio frequency sampling and detection unit includes a coupling module, an attenuation module, and a detection module, which are connected in series. The input terminal of the coupling module is connected to the klystron radio frequency output unit.
3. The low-delay klystron standing wave protection system based on a high-speed comparator circuit according to claim 2, characterized in that, The signal processing and decision unit is equipped with two sets of digital-to-analog conversion modules, a signal processing and signal discrimination module, and a high-speed comparison module. The first set of digital-to-analog conversion modules is connected to the input end of the signal processing and signal discrimination module, and the output end of the signal processing and signal discrimination module is connected to the high-speed comparison module through the second coarse digital-to-analog conversion module.
4. The low-delay klystron standing wave protection system based on a high-speed comparator circuit according to claim 3, characterized in that, The detection module is connected to the two input terminals of the first set of digital-to-analog converter modules through forward wave analog signals and reflected wave analog signals.
5. The low-delay klystron standing wave protection system based on a high-speed comparator circuit according to claim 4, characterized in that, The detection module is communicatively connected to the input of the high-speed comparison module via a reflected wave analog signal.
6. The low-delay klystron standing wave protection system based on a high-speed comparator circuit according to claim 5, characterized in that, The output of the signal processing and signal identification module is connected to the machine interlocking execution unit via a digital protection signal path.
7. The low-delay klystron standing wave protection system based on a high-speed comparator circuit according to claim 6, characterized in that, The output of the high-speed comparison module is connected to the machine interlocking execution unit via an analog protection signal path.
8. The control method for a low-delay klystron standing wave protection system based on a high-speed comparator circuit as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Acquire the forward microwave signal and the reflected microwave signal at the output of the klystron, and convert them into a forward analog voltage signal and a reflected analog voltage signal; S2. Parallel execution of digital protection processing flow and analog protection comparison flow; The digital protection processing flow is to convert the forward analog voltage signal and the reflected analog voltage signal into digital signals, calculate the protection parameters based on the digital signals, and generate the first interlocking signal by comparing the protection parameters with the first protection threshold. The analog protection comparison process involves comparing the reflected analog voltage signal with an analog voltage threshold in real time using hardware to generate a second interlocking signal. S3. Receive the first interlock signal and the second interlock signal, and generate and output a system shutdown command when either signal indicates a fault.
9. The control method for the low-delay klystron standing wave protection system based on a high-speed comparator circuit according to claim 8, characterized in that, The specific steps in step S2 for calculating the protection parameters based on the digital signal are as follows: The two digital signals are filtered; the filtered digital signals are converted into forward power and reflected power values through a lookup table; the difference between the forward power and reflected power values is calculated to obtain the return loss value as the protection parameter.
10. The control method for the low-delay klystron standing wave protection system based on a high-speed comparator circuit according to claim 9, characterized in that, The analog voltage threshold in step S2 is dynamically generated by a signal processor based on the system operating status and provided by a digital-to-analog converter; real-time hardware comparison is performed by a high-speed comparator.