A design method of adjustable high-precision sampling signal monitoring and protection circuit system

Abstract

This invention relates to the field of power electronics technology, and more particularly to a design method for an adjustable high-precision sampling signal monitoring and protection circuit system. The technical solution includes the following steps: threshold setting, by adjusting the first adjustable resistor RP1 in the signal input and reference module to set the maximum output voltage of a reference circuit; and by adjusting an external knob JP3 to control the voltage input to the first operational amplifier to obtain a pre-set threshold electrical signal. This invention, through step-by-step adjustment of the adjustable resistor and external knob, in conjunction with a precision reference source, instrumentation amplifier, operational amplifier comparison channel, and isolation optocoupler, achieves precise threshold tuning, flexible matching of sampling signals, and reliable isolated output. The design method provides a quantitative calculation formula, solving the problems of poor reference stability, low threshold tuning accuracy, insufficient signal matching, and weak isolation and anti-interference capabilities in existing technologies.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a design method for an adjustable high-precision sampling signal monitoring and protection circuit system. Background Technology

[0002] With the continuous development of power systems and industrial automation technologies, higher requirements are being placed on the real-time monitoring and reliable protection of voltage and current signals. In various power electronic devices and systems, signal acquisition, reference threshold setting, signal comparison and discrimination, protection command isolation output, and status visualization feedback constitute the core workflow of the monitoring and protection system. The coordination and parameter matching between these links directly determine the system's monitoring accuracy and the reliability of its protection actions.

[0003] In existing technologies, traditional voltage signal monitoring and protection systems typically employ discrete circuit module designs, where differential amplification, threshold setting, sampling ratio, and isolated transmission are implemented by separate functional circuit units, which are then combined through system cascading. This approach not only increases the complexity of circuit design and hardware costs but also suffers from several shortcomings:

[0004] (1) Poor stability of reference voltage: The threshold setting circuit often uses simple resistor voltage divider or ordinary Zener diode to provide reference. Its temperature drift coefficient is large and its resistance to power fluctuation is weak, which causes the preset threshold to shift with the ambient temperature and working time, affecting the accuracy and consistency of the protection criteria.

[0005] (2) Low threshold setting accuracy: Threshold adjustment usually relies on a single adjustable element, lacking a mechanism for coarse and fine adjustment, resulting in limited setting resolution and difficulty in meeting the requirements for precise setting of threshold voltage in high-precision monitoring scenarios.

[0006] (3) Insufficient matching degree between signal amplification and threshold: The voltage / current signals to be measured in the power system are mostly weak differential signals, which are easily affected by common-mode interference in the field, and their amplitude range varies greatly. In the existing schemes, the gain settings of the amplifier circuit are mostly fixed values ​​or have limited adjustable ranges, which makes it difficult to flexibly adapt to the signal conditioning requirements of different amplitude conditions, and easily leads to low sampling accuracy or distortion of the input of the subsequent circuit due to over-range.

[0007] (4) Weak isolation and anti-interference capability: The electrical isolation measures between the protection command output link and the control circuit are insufficient. Strong electrical interference in the field can easily enter the weak electrical control module, causing damage to core components or protection malfunctions and failures to operate. The long-term stability of the system is difficult to guarantee.

[0008] Existing technical literature, such as the Chinese patent publication "A Weak Signal and Wide Dynamic Range Acquisition Circuit for High-Precision Instruments" (CN119892074A), while achieving basic signal acquisition, monitoring, and protection functions and simplifying circuit debugging processes in small-scale application scenarios to some extent, still lacks a standardized parameter tuning and design methodology. Its circuit adjustability is limited, and its compatibility with different monitoring devices and power signals of varying amplitude characteristics is poor. Furthermore, this solution lacks reliable parameter constraints and quantitative design basis in the isolation output stage, and under long-term operating conditions, it still faces potential risks such as signal distortion, protection threshold drift, and abnormal operation logic, making it difficult to meet the core application requirements of high precision, high adaptability, and high stability for voltage monitoring and protection systems in the industrial and power sectors. Therefore, this application proposes a design method for an adjustable high-precision sampling signal monitoring and protection circuit system. Summary of the Invention

[0009] The purpose of this invention is to address the problems of poor reference voltage stability and low threshold setting accuracy in existing voltage signal monitoring and protection systems in the background art, and to propose a design method for an adjustable high-precision sampling signal monitoring and protection circuit system.

[0010] In a first aspect, this application provides a design method for an adjustable high-precision sampling signal monitoring and protection circuit system. The circuit system includes a signal input and reference module, a high-precision differential amplification module, a threshold comparison and isolation output module, and a display output and power supply module. The design method includes the following steps:

[0011] The threshold setting is achieved by adjusting the first adjustable resistor RP1 in the signal input and reference module to set the maximum output voltage of a reference circuit; and by adjusting an external knob JP3 to control the voltage input to the first operational amplifier to obtain a set threshold electrical signal.

[0012] The sampling ratio is adjusted by adjusting the second adjustable resistor RP2 to control the sampling ratio of the threshold electrical signal output to the sampling port of a display screen;

[0013] Gain adjustment: Based on the signal to be measured collected from the power system, the gain of the instrumentation amplifier is set by adjusting the resistance value of the third adjustable resistor RP3 connected to the gain setting terminal of the instrumentation amplifier in the high-precision differential amplifier module, so as to adjust the sampling voltage amplitude of the signal to be measured after differential amplification and obtain a processed sampling signal.

[0014] The comparison and isolation output module inputs the set threshold electrical signal and the processed sampling signal to the first comparison channel and the second comparison channel of the second operational amplifier in the threshold comparison and isolation output module for amplitude comparison, and outputs the comparison result after electrical isolation via an isolation optocoupler.

[0015] Optionally, the threshold setting step further includes:

[0016] An adjustable reference voltage branch is formed by a precision reference source and the first adjustable resistor RP1 to provide a reference voltage; and the reference voltage is divided twice by the voltage divider network formed by the external knob JP3 to obtain the voltage input to the first operational amplifier.

[0017] The highest output voltage of the reference circuit satisfies the following relationship:

[0018] The amplitude of the threshold electrical signal output by the first operational amplifier The following relationship must be satisfied:

[0019] In the formula, This indicates the highest output voltage of the reference circuit. The internal reference voltage value of the precision reference source. This is the nominal total resistance value of the first adjustable resistor. This is the fixed resistance value corresponding to the voltage divider terminal of the first adjustable resistor in the current adjustment state. This refers to the adjustable voltage divider resistance value corresponding to the external knob in the current adjustment state. Let be the total resistance of the branches in the voltage divider network. The output voltage value is the result of the reference voltage being divided twice.

[0020] Optionally, the sampling ratio adjustment step further includes:

[0021] A voltage divider-type adjustable sampling circuit is formed by the second adjustable resistor RP2 and a fixed matching resistor to proportionally attenuate the threshold electrical signal.

[0022] The signal sampling ratio satisfies the following relationship:

[0023] The sampled voltage value output to the sampling port of the display screen satisfies the following relationship and constraints:

[0024] In the formula, The sampling ratio of the signal. The threshold electrical signal amplitude before attenuation. The sampled voltage value is the output after attenuation. This is the rated maximum input voltage value of the sampling port of the display screen. This represents the real-time resistance value of the second adjustable resistor in the current adjustment state. The value of the fixed matching resistor.

[0025] Optionally, the gain adjustment step further includes: connecting the signal to be measured as a differential input signal to the input terminal of the instrumentation amplifier; wherein the gain of the instrumentation amplifier satisfies the following relationship: ,in, The resistor value is set to the preset gain of the instrumentation amplifier; the amplitude of the sampled voltage output after amplification and adjustment satisfies the following relationship and constraints: In the formula, For the gain of the instrumentation amplifier, The original differential voltage amplitude of the signal under test. The amplitude of the sampled voltage output after amplification and adjustment. This is the rated maximum input voltage value of the subsequent circuit. This is the real-time resistance value of the third adjustable resistor in the current adjustment state.

[0026] Optionally, the comparison and isolation output step further includes:

[0027] The first comparator channel of the second operational amplifier is configured to output a first logic level when the amplitude of the processed sampled signal is greater than the amplitude of the preset threshold electrical signal.

[0028] The second comparator channel of the second operational amplifier is configured to output a second logic level when the amplitude of the processed sampled signal is less than or equal to the amplitude of the preset threshold electrical signal.

[0029] The first logic level and the second logic level are respectively transmitted to the input side of the corresponding isolation optocoupler, so as to obtain an output signal corresponding to the comparison result and achieving electrical isolation at the output side of the isolation optocoupler.

[0030] Optionally, the precision reference source is a TL431 type adjustable precision reference source, whose internal reference voltage... It is 2.5V.

[0031] Optionally, the instrumentation amplifier is an INA114 type instrumentation amplifier, which has a preset gain setting resistor value. It is 50kΩ.

[0032] Optionally, the output side of the isolation optocoupler is connected to a status indication circuit, which is used to drive at least one light-emitting diode according to the output signal to provide a visual status indication corresponding to the comparison result.

[0033] Secondly, this application provides an adjustable high-precision sampling signal monitoring and protection circuit system, comprising:

[0034] The signal input and reference module is used to generate an adjustable threshold electrical signal;

[0035] A high-precision differential amplifier module is used to perform differential amplification with adjustable gain on the signal to be measured collected from the power system, so as to output the processed sampled signal.

[0036] The threshold comparison and isolation output module has its input terminals connected to the output terminals of the signal input and reference module and the high-precision differential amplifier module, respectively. It is used to compare the amplitude of the threshold electrical signal with the sampled signal and output the comparison result after electrical isolation.

[0037] The display output and power supply module is used to provide operating power to each module and output the current set value of the threshold electrical signal to a display screen for display.

[0038] The circuit parameters of the signal input and reference module, the high-precision differential amplifier module, and the threshold comparison and isolation output module are configured to be tuned using the design method described in the first aspect.

[0039] Optionally, the circuit system is used for monitoring and protecting a high-voltage pulse power supply, which includes a laser xenon lamp driver power supply or a pulse power device.

[0040] Compared with the prior art, this application includes at least one of the following beneficial technical effects:

[0041] This application sets the highest output voltage of the reference by using a precision reference source and a first adjustable resistor, and then uses an external high-precision knob for secondary voltage division adjustment to achieve a combination of coarse and fine adjustment of the threshold electrical signal. This improves the setting resolution, allows for quantitative calculation of the setting range, and meets the protection threshold setting requirements of different voltage levels.

[0042] A voltage divider circuit is formed by the second adjustable resistor and the fixed matching resistor to adjust the sampling ratio of the output to the sampling port of the display screen, so that the sampling voltage does not exceed the rated input range of the display screen, thus avoiding signal distortion due to exceeding the range or insufficient sampling accuracy.

[0043] The gain of the instrumentation amplifier is set by the third adjustable resistor, so that the original differential sampling signals of different amplitudes are amplified and adapted to the input range of the subsequent comparison circuit. The gain calculation formula is clear and the parameter tuning is based on the evidence, avoiding signal saturation distortion or recognition failure.

[0044] The threshold electrical signal and the amplified sampling signal are respectively connected to the two comparison channels of the second operational amplifier for amplitude comparison. The comparison result is output after electrical isolation by an isolation optocoupler, realizing electrical isolation between the control circuit and the monitoring circuit, and reducing the impact of field interference on protection action.

[0045] In summary, this invention achieves precise threshold tuning, flexible sampling signal matching, and reliable isolated output by adjusting the adjustable resistor and external knob in stages, in conjunction with a precision reference source, instrumentation amplifier, operational amplifier comparison channel, and isolation optocoupler. The design method provides a quantitative calculation formula, solving the problems of poor reference stability, low threshold tuning accuracy, insufficient signal matching, and weak isolation and anti-interference capabilities in existing technologies. Attached Figure Description

[0046] Figure 1 This is a structural diagram of the adjustable high-precision sampling signal monitoring and protection circuit system in this invention;

[0047] Figure 2 This is a flowchart of the adjustable high-precision sampling signal monitoring and protection circuit system in this invention;

[0048] Figure 3 This is a circuit diagram of the adjustable high-precision sampling signal monitoring and protection circuit system in this invention;

[0049] Figure 4 This is a waveform diagram of the normal operation of the 1900V high-voltage pulse in this invention;

[0050] Figure 5 This is a diagram showing the 1900V high-voltage pulse overvoltage threshold and the sampling signal waveform in this invention;

[0051] Figure 6 This is the waveform diagram of the 2000V high-voltage pulse reaching the trigger value in this invention;

[0052] Figure 7 This is a diagram showing the 2000V high-voltage pulse overvoltage threshold and the waveform of the sampled signal in this invention;

[0053] Figure 8 This is the waveform diagram of the 2500V high-voltage pulse overvoltage protection in this invention;

[0054] Figure 9 This is a diagram showing the 2500V high-voltage pulse overvoltage threshold and the sampling signal waveform in this invention. Detailed Implementation

[0055] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0056] Example: This example discloses a design method for an adjustable high-precision voltage signal monitoring and protection circuit system, proposing a system design scheme that meets the requirements of precise voltage and current control, real-time monitoring, and status indication in power systems. This method belongs to the field of power electronics technology. The adjustable high-precision voltage signal monitoring and protection system includes: a signal input and reference module, a display output and power supply module, a high-precision differential amplification module, and a threshold comparison and isolation output module. The parameter design method of this invention includes the following steps:

[0057] 1. Set the maximum output voltage of the reference circuit using the adjustable resistor RP1, then adjust the external high-precision knob on JP3 to control the voltage input to the OP2131 operational amplifier, thus completing the threshold signal setting. The threshold signal parameters are set as follows:

[0058] In high-precision voltage signal monitoring and protection systems, the precise setting of the threshold electrical signal directly determines the system's monitoring accuracy and the reliability of its protection actions, requiring both a wide adjustable range and high reference stability. To meet this requirement, a circuit combination of a precision reference voltage divider and an external knob linkage is adopted. In the front stage, the maximum output voltage of the reference circuit is set through the adjustable resistor RP1, establishing a stable and adjustable reference voltage branch. In the rear stage, the external high-precision knob JP3 is adjusted to regulate the voltage division ratio of the voltage divider branch, precisely controlling the voltage amplitude input to the OP2131 operational amplifier, thus completing the precise setting of the threshold electrical signal.

[0059] Assume the internal reference voltage of the TL431 precision reference source is The total resistance of the adjustable resistor RP1 is The voltage divider terminal set resistance is Then the highest output voltage of the reference circuit for: ;

[0060] Assume the adjustable voltage divider resistance value corresponding to the external high-precision knob of JP3 is... The total resistance of the voltage divider branch is The reference circuit outputs a voltage through a voltage divider via JP3. The threshold voltage output by the OP2131 op-amp is: ;

[0061] Based on the above formula, the setting range of the threshold electrical signal can be determined as follows: ,in This is the op-amp input voltage when the JP3 knob is adjusted to the minimum resistance value. This is the op-amp input voltage when JP3 knob is adjusted to its maximum resistance and RP1 is adjusted to the highest reference output.

[0062] in, This indicates the internal reference voltage of the precision reference source. This indicates the total resistance of the adjustable resistor RP1. This indicates the fixed resistance value at the voltage divider terminal. This indicates the highest output voltage of the reference circuit. This indicates the adjustable voltage divider resistance value corresponding to the external high-precision knob of JP3. This represents the total resistance of the voltage divider branch. Indicates the output voltage of the reference circuit. This represents the threshold voltage output by the OP2131 op-amp.

[0063] 2. Adjust the adjustable resistor RP2 to control the signal sampling ratio of the threshold electrical signal output to the display sampling port; the sampling ratio parameter is calculated as follows:

[0064] In high-precision voltage signal monitoring and protection systems, the display screen's sampling port has a rated input range limitation. The threshold electrical signal amplitude must match the sampling port's adaptation range; direct transmission can easily lead to signal distortion due to exceeding the range or insufficient sampling accuracy. To meet this requirement, a voltage divider-type adjustable sampling circuit is used. By adjusting the adjustable resistor RP2, the resistance ratio of the voltage divider branches is changed, precisely controlling the sampling ratio of the threshold electrical signal output to the display screen's sampling port, ensuring stable and compliant sampling signals and accurate and effective data acquisition.

[0065] Let the resistance of the adjustable resistor RP2 be... The voltage divider branch has a fixed matching resistance value of Then the sampling ratio of the threshold electrical signal can be expressed as: ;

[0066] The original threshold electrical signal amplitude is That is, the threshold voltage output by the OP2131 operational amplifier, after proportional regulation, is the sampling voltage output to the sampling port of the display screen: ;

[0067] When the sampling range of the display screen is adapted, the sampling voltage meets the rated constraints: ≤ ,in The rated maximum input voltage for the display sampling port;

[0068] Based on the above formula, the value of the adjustable resistor RP2 for adapting the sampling range can be calculated as follows: ;

[0069] in, This indicates the sampling ratio of the threshold electrical signal output to the display sampling port. This represents the threshold voltage output by the OP2131 op-amp. This represents the sampled output voltage after regulation. This indicates the rated maximum input voltage of the display screen's sampling port. This indicates the real-time resistance value of the adjustable resistor RP2. Indicates the fixed matching resistance value of the voltage divider branch.

[0070] 3. Based on the voltage / current signals collected by the power system, the operational amplifier gain is adjusted by adjusting the external adjustable resistor RP3 of the high-precision operational amplifier to regulate the amplitude of the sampled voltage signal; the operational amplifier gain and sampled voltage amplitude parameters are calculated as follows:

[0071] The voltage / current signals acquired by power systems are mostly weak differential signals, which are susceptible to common-mode interference in the field. Furthermore, their amplitudes cannot be directly matched to the input ranges of subsequent monitoring and protection circuits, easily leading to low sampling accuracy and signal recognition failures. To meet this requirement, a circuit combination of a high-precision instrumentation operational amplifier and an external adjustable resistor is used. This circuit connects the raw voltage / current sampling signals acquired by the power system to the differential input of the operational amplifier. By adjusting the external adjustable resistor RP3 of the high-precision operational amplifier, the operating gain of the operational amplifier is set, precisely adjusting the amplitude of the sampled voltage signal to ensure that the signal is matched to the range of subsequent circuits and that the monitoring data is accurate and reliable.

[0072] The formula for calculating the rated gain of a high-precision operational amplifier is: ;

[0073] Let the original differential sampling voltage collected by the power system be... The amplitude of the output sampled voltage after amplification and adjustment by the operational amplifier for: ;

[0074] With the range adapted to the subsequent circuit, the adjusted output sampling voltage meets the constraints: ≤ ,in This is the rated maximum input voltage for the subsequent monitoring and protection circuit;

[0075] Based on the above formula, the value of the adjustable resistor RP3 for adapting the sampling voltage amplitude can be calculated as follows: ;

[0076] in, This indicates the operating gain of the high-precision operational amplifier. This represents the raw differential sampling voltage collected by the power system. This indicates the amplitude of the sampled output voltage after adjustment. This indicates the rated maximum input voltage of the subsequent monitoring and protection circuit. This indicates the real-time resistance value of the external adjustable resistor RP3 of the high-precision operational amplifier.

[0077] 4. The pre-set threshold electrical signal is compared with the sampled signal processed by the high-precision differential amplifier module, and then sent to the upper and lower channels of the operational amplifier LM358. The comparison result is output after isolation by the optocoupler PC817. The signal comparison and isolation output parameters are adjusted as follows:

[0078] In high-precision voltage signal monitoring and protection systems, it is necessary to accurately determine the relationship between the amplitude of the sampled signal and the preset threshold. Furthermore, the control loop and monitoring loop must be electrically isolated to prevent strong electrical interference from entering the weak current module and damaging core components, while ensuring reliable transmission of protection action commands. To meet this requirement, a circuit combination of operational amplifier comparison and optocoupler isolation is adopted. This circuit compares the preset threshold electrical signal with the sampled signal processed by the high-precision differential amplifier module, sending them to the upper and lower channels of the operational amplifier LM358. The comparison result is then electrically isolated by the optocoupler PC817 before being output, completing the dual functions of signal comparison and isolated transmission.

[0079] The on-channel compare-to-flip threshold of the LM358 op-amp meets the following requirements: The channel compare-to-flip threshold of the LM358 op-amp satisfies: ,in, The amplitude of the sampled signal after differential amplification. This represents the threshold voltage output by the OP2131 op-amp;

[0080] Figure 1 The diagram shows the system structure of an adjustable high-precision sampling signal monitoring and protection circuit, illustrating the connection relationships and signal transmission directions of the system's four core modules (signal input and reference module, display output and power supply module, high-precision differential amplifier module, threshold comparison and isolation output module).

[0081] The system's operation strictly follows a closed-loop logic: signal acquisition—reference setting—amplitude comparison—graded triggering—isolation output—status feedback. The specific steps are as follows:

[0082] 1. System Startup and Module Initialization: After the system is powered on, it enters the "Start" stage. The reference circuit and operational amplifier circuit synchronously complete the power supply initialization to prepare for subsequent signal processing and threshold determination.

[0083] 2. Threshold voltage setting and display: The reference circuit outputs a stable and adjustable threshold voltage by adjusting the internal adjustable resistors (RP1 / RP2); this threshold voltage is synchronously sent to the display screen to display the currently set protection threshold parameters in real time, which is convenient for on-site debugging and monitoring.

[0084] 3. Sampling signal amplification and preprocessing: The operational amplifier circuit sets the operating gain of the operational amplifier by adjusting the gain resistor (RP3), and performs high-precision amplification processing on the differential voltage / current signal collected by the power system to generate a sampling voltage that is adapted to the range of the subsequent circuit.

[0085] 4. Signal amplitude comparison and determination: The threshold voltage and the sampled voltage are sent to the upper and lower channels of the operational amplifier for signal comparison, and then proceed to the signal amplitude determination stage.

[0086] Operating conditions not exceeding limits: If the sampled voltage is less than the threshold voltage, the system is determined to be in normal operating condition, there is no protection trigger, the sampled voltage is continuously collected in a loop, and normal monitoring is maintained.

[0087] Over-limit conditions: If the sampled voltage is greater than or equal to the threshold voltage, the system further distinguishes between two levels of protection thresholds:

[0088] Threshold trigger: When the sampled voltage reaches the preset threshold, the threshold trigger process is initiated. The optocoupler is driven by adjusting the corresponding resistor to output an isolated threshold trigger signal.

[0089] Overvoltage threshold trigger: When the sampled voltage exceeds the preset overvoltage threshold, the overvoltage trigger process is initiated. The corresponding resistor is adjusted to drive the optocoupler, and an isolated overvoltage trigger signal is output to trigger the emergency protection action.

[0090] 5. Isolation Output and Status Feedback: The overvoltage trigger signal is electrically isolated and output via optocoupler to prevent strong and weak electrical interference from entering the subsequent circuits; at the same time, the display screen updates the system voltage demand status synchronously to achieve visual feedback; under the condition of not exceeding the limit, the signal is continuously collected in a loop to complete closed-loop real-time monitoring.

[0091] Figure 2 This is a flowchart illustrating the operation of an adjustable high-precision sampling signal monitoring and protection circuit system. It shows the closed-loop operation logic of the system from startup initialization to signal acquisition, reference tuning, amplitude comparison, graded triggering, isolation output, and status feedback.

[0092] To demonstrate the reliability of the circuit system in practice and operation, the following circuit is designed with the following parameters:

[0093] (1) Signal Input and Reference Module

[0094] The reference source uses a TL431 precision reference chip, along with a 10kΩ adjustable resistor RP1, a 1kΩ fixed resistor R31, and 10kΩ voltage divider resistors R33 / R37, to achieve precise adjustment of the highest reference output voltage. The signal buffer uses an OP2131 low-noise operational amplifier (U10A) to buffer and amplify the threshold signal. The input signal is controlled by an external high-precision knob connected to JP3 in conjunction with the reference circuit. The filtering design incorporates multiple 1µF (Type 105) capacitors (C31 / C32 / C34), 0.1µF (Type 104) capacitors (C33 / C35), and a 1kΩ fixed resistor R34 for power supply decoupling and signal filtering to suppress interference.

[0095] Power supply: ±12VDC dual power supply to ensure stable operation of operational amplifiers and reference sources.

[0096] (2) Display output and power supply module

[0097] The proportional adjustment is achieved through a 10kΩ adjustable resistor RP2, a 10kΩ fixed resistor R50, and a 1µF filter capacitor C36, which adjusts the sampling ratio of the threshold electrical signal to the display sampling port (Screen+). The display interface JP4 provides +5VDC, GND, and Screen+ signals for connecting to the display screen to visualize the threshold parameters.

[0098] (3) High-precision differential amplifier module

[0099] Differential sampling employs the INA114 high-precision differential amplifier (U11) to perform differential sampling of power system voltage / current signals. Gain adjustment is achieved through a 500kΩ adjustable resistor RP3, along with external components such as 10kΩ fixed resistors R65 / R70, allowing for flexible amplifier gain settings to accommodate sampling signals of different amplitudes. The filtering design incorporates 47µF (C41 / C43) and 1µF (C42 / C48) capacitors to perform power supply and signal filtering, thereby improving sampling accuracy.

[0100] Power supply: ±12VDC dual power supply.

[0101] (4) Threshold comparison and isolation output module

[0102] The signal comparison uses LM358 dual op-amps (U9A / U9B) to construct two comparison channels, which perform threshold comparisons on the "overvoltage (Uover)" and "upset (Uset)" signals respectively. Electrical isolation is achieved through PC817 linear optocouplers (IC2 / IC3) to avoid interference in subsequent stages. Protection and indication are configured with 1000Ω / 300Ω / 200Ω current-limiting resistors (R36 / R39 / R40, etc.) to protect the optocouplers, and red LEDs (D13 / D14), yellow LEDs (D15), and green LEDs (D17) to provide visual indication of overvoltage, upset, and normal status. Output sampling is completed through 10kΩ voltage divider resistors (R53 / R54), 20kΩ resistors (R57 / R58), and 1µF capacitors (C39 / C40) to complete the sampling and filtering of the output signal.

[0103] Figure 3 The circuit diagram of the adjustable high-precision sampling signal monitoring and protection circuit system shows the specific component selection, parameter configuration, circuit connection and signal interface design of the four major modules.

[0104] To verify the reliability of the circuit system, the design will be adapted to the operational monitoring requirements of industrial high-voltage pulse power supplies (such as laser xenon lamp power supplies and pulse power devices). The threshold triggering accuracy, sampling linearity, and system stability of the designed high-voltage pulse monitoring circuit under different amplitude high-voltage pulse conditions will be verified. This ensures the circuit can accurately identify "operation at the set value" and "overvoltage fault" states, providing a reliable basis for the safety protection and status monitoring of the power system. Test objects: OP2131 threshold based on TL431 precision reference, xenon lamp capacitor energy storage high voltage, INA114 differential sampling, output status signal after LM358 comparison and PC817 optocoupler isolation. A high-voltage pulse signal capable of outputting three amplitude levels (1900V / 2000V / 2500V), a repetition frequency of 1kHz, and a duty cycle of 50% will be used to simulate actual pulse conditions in a power system.

[0105] (1) Test waveforms and operating conditions

[0106] This test focused on the high-voltage pulse monitoring circuit of the power system. The physical meaning of each test waveform was clear: the measured high voltage of the circuit... (Scale 1kV / Div) is defined as the high-voltage pulse signal input to the system; the voltage after the reference signal is processed by the operational amplifier. The sampling signal taken with the step-down voltage (Scale 2V / Div), where To represent the threshold voltage output by the OP2131 op-amp, This is the amplitude of the sampled signal after differential amplification; the user sets the charging state voltage to the corresponding threshold. (Scale 5V / Div), Overvoltage state output signal voltage (Scale 5V / Div) is defined as the status output signal when the high voltage pulse exceeds the set overvoltage threshold.

[0107] (2) Voltage level test response: Under the actual high voltage condition of 1900V, the actual high voltage... Presenting a regular pulse waveform, the threshold voltage output by the OP2131 op-amp Sampling signal Maintain a period consistent with the high-voltage pulse, and adapt the amplitude to the level range of the subsequent comparator circuit. (Reach signal) Continuous low output, reaching the target value but not triggered; overvoltage signal. Maintaining a low level and not triggering an overvoltage condition indicates that the voltage condition is either at the set value or overvoltage.

[0108] In the actual high-voltage operating condition of 2000V, with the high voltage... The increased pulse amplitude demonstrates good sampling linearity, and the sampled signal... It maintains the same period as the high-voltage pulse, and its amplitude matches the level range of the subsequent comparator circuit. (Reach signal) Continuous high-level output, maintaining a stable state upon reaching the target value; overvoltage signal. It remains at a low level, verifying that the threshold voltage is triggered within the 2000V range, while the overvoltage threshold is still higher than 2000V.

[0109] In the actual measured high-voltage condition of 2500V, with the high voltage... When the pulse amplitude further increases to 2500V, the sampling signal It continues to synchronously follow the changes in the high-voltage pulse without distortion or falsification, maintaining stable sampling linearity. At this point, the signal reaches its maximum value. Continuous high-level output (value reached continuously), overvoltage signal A synchronous high-level output triggers an overvoltage condition, indicating that the overvoltage threshold has been accurately applied within the 2000V~2500V range, and the circuit can accurately identify overvoltage conditions.

[0110] Figures 4-9 The diagram shows the operating waveforms of the adjustable high-precision sampling signal monitoring and protection circuit system. (a) and (b) are the waveforms under normal operating conditions of 1900V, (c) and (d) are the waveforms under operating conditions of 2000V reaching the target value, and (e) and (f) are the waveforms under operating conditions of 2500V overvoltage. Each sub-diagram shows the waveform changes and corresponding relationships of the measured high voltage, reference threshold, sampling signal, target value signal, and overvoltage signal.

[0111] It is worth noting that this invention constructs a reference branch with adjustable maximum output voltage by using a precision reference source (TL431) and a first adjustable resistor (RP1), and uses an external high-precision knob (JP3) to achieve secondary voltage division adjustment of the reference voltage. This combines coarse and fine adjustment, improves the setting resolution of the threshold electrical signal, and allows the setting range to be quantitatively calculated and set, meeting the precise setting requirements of protection thresholds for monitoring scenarios of different voltage levels.

[0112] In this invention, a voltage divider-type adjustable sampling circuit composed of a second adjustable resistor (RP2) and a fixed matching resistor can quantitatively adjust the sampling ratio of the threshold electrical signal output to the sampling port of the display screen, so that the sampling voltage is always adapted to the rated input range of the sampling port of the display screen, avoiding the problem of signal distortion due to exceeding the range or insufficient sampling accuracy, and ensuring the stability and accuracy of the display parameters.

[0113] In addition, by setting the gain of the instrumentation amplifier (INA114) through the third adjustable resistor (RP3), the amplification factor of the weak differential signal collected from the power system can be flexibly adjusted, so that the amplitude of the amplified sampling voltage is adapted to the input range of the subsequent comparator circuit. The gain calculation formula is clear, and the parameter tuning is based on evidence, which solves the problem of low sampling accuracy or saturation distortion of the subsequent circuit caused by signal amplitude mismatch.

[0114] Furthermore, this invention compares the threshold electrical signal and the amplified sampled signal by inputting them separately into two independent comparison channels of the second operational amplifier (LM358). The comparison logic is clear, corresponding to the judgment of two operating conditions: "reaching the threshold" and "overvoltage." The comparison result is output after electrical isolation via an isolation optocoupler (PC817), achieving electrical isolation between the control loop and the monitoring loop, reducing the impact of strong electrical interference on the weak electrical module, and reducing the probability of protection malfunction or failure to operate. The design method provided by this invention gives clear calculation formulas and constraints for the parameter tuning of each key link, including the threshold voltage range, sampling ratio, operational amplifier gain, and output sampled voltage amplitude, etc., transforming circuit design from relying on experience-based debugging to quantitative calculation based on formulas, improving the reproducibility of the design method and its adaptability to different application scenarios. The circuit system consists of a signal input and reference module, a high-precision differential amplifier module, a threshold comparison and isolation output module, and a display output and power supply module. Each module has independent functions and clear interfaces, facilitating parameter adjustment or module replacement for different monitoring objects, reducing the complexity of system debugging and subsequent maintenance.

[0115] In summary, the adjustable high-precision sampling signal monitoring and protection circuit system design method of this invention, through step-by-step adjustment of adjustable resistors (RP1, RP2, RP3) and external knob (JP3), in conjunction with a precision reference source, instrumentation amplifier, operational amplifier comparison channel, and isolation optocoupler, achieves precise threshold voltage setting, flexible matching of sampling signals, and reliable isolated output. This method provides clear parameter calculation formulas and constraints, making the circuit design process quantitative and standardized. It solves the problems of poor reference stability, low threshold setting accuracy, insufficient signal matching, and weak isolation and anti-interference capabilities in existing technologies, and can meet the technical requirements for precise voltage and current monitoring and protection in power systems.

[0116] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A design method for an adjustable high-precision sampling signal monitoring and protection circuit system, the circuit system comprising a signal input and reference module, a high-precision differential amplification module, a threshold comparison and isolation output module, and a display output and power supply module, characterized in that, The design method includes the following steps: The threshold setting is achieved by adjusting the first adjustable resistor RP1 in the signal input and reference module to set the maximum output voltage of a reference circuit; and by adjusting an external knob JP3 to control the voltage input to the first operational amplifier to obtain a set threshold electrical signal. The sampling ratio is adjusted by adjusting the second adjustable resistor RP2 to control the sampling ratio of the threshold electrical signal output to the sampling port of a display screen; Gain adjustment: Based on the signal to be measured collected from the power system, the gain of the instrumentation amplifier is set by adjusting the resistance value of the third adjustable resistor RP3 connected to the gain setting terminal of the instrumentation amplifier in the high-precision differential amplifier module, so as to adjust the sampling voltage amplitude of the signal to be measured after differential amplification and obtain a processed sampling signal. The comparison and isolation output module inputs the set threshold electrical signal and the processed sampling signal to the first comparison channel and the second comparison channel of the second operational amplifier in the threshold comparison and isolation output module for amplitude comparison, and outputs the comparison result after electrical isolation via an isolation optocoupler.

2. The design method for an adjustable high-precision sampling signal monitoring and protection circuit system according to claim 1, characterized in that, The threshold setting step further includes: An adjustable reference voltage branch is formed by a precision reference source and the first adjustable resistor RP1 to provide a reference voltage; and the reference voltage is divided twice by the voltage divider network formed by the external knob JP3 to obtain the voltage input to the first operational amplifier. The highest output voltage of the reference circuit satisfies the following relationship: ; The amplitude of the threshold electrical signal output by the first operational amplifier The following relationship must be satisfied: ; In the formula, This indicates the highest output voltage of the reference circuit. The internal reference voltage value of the precision reference source. This is the nominal total resistance value of the first adjustable resistor. This is the fixed resistance value corresponding to the voltage divider terminal of the first adjustable resistor in the current adjustment state. This refers to the adjustable voltage divider resistance value corresponding to the external knob in the current adjustment state. Let be the total resistance of the branches in the voltage divider network. The output voltage value is the result of the reference voltage being divided twice.

3. The design method for an adjustable high-precision sampling signal monitoring and protection circuit system according to claim 1, characterized in that, The sampling ratio adjustment step further includes: A voltage divider-type adjustable sampling circuit is formed by the second adjustable resistor RP2 and a fixed matching resistor to proportionally attenuate the threshold electrical signal. The signal sampling ratio satisfies the following relationship: ; The sampled voltage value output to the sampling port of the display screen satisfies the following relationship and constraints: ; In the formula, The sampling ratio of the signal. The threshold electrical signal amplitude before attenuation. The sampled voltage value is the output after attenuation. This is the rated maximum input voltage value of the sampling port of the display screen. This represents the real-time resistance value of the second adjustable resistor in the current adjustment state. The value of the fixed matching resistor.

4. The design method for an adjustable high-precision sampling signal monitoring and protection circuit system according to claim 1, characterized in that, The gain adjustment step further includes: connecting the signal to be measured as a differential input signal to the input terminal of the instrumentation amplifier; wherein the gain of the instrumentation amplifier satisfies the following relationship: ,in, The resistor value is set to the preset gain of the instrumentation amplifier; the amplitude of the sampled voltage output after amplification and adjustment satisfies the following relationship and constraints: In the formula, For the gain of the instrumentation amplifier, The original differential voltage amplitude of the signal under test. The amplitude of the sampled voltage output after amplification and adjustment. This is the rated maximum input voltage value of the subsequent circuit. This is the real-time resistance value of the third adjustable resistor in the current adjustment state.

5. The design method for an adjustable high-precision sampling signal monitoring and protection circuit system according to claim 1, characterized in that, The comparison and isolation output step further includes: The first comparator channel of the second operational amplifier is configured to output a first logic level when the amplitude of the processed sampled signal is greater than the amplitude of the preset threshold electrical signal. The second comparator channel of the second operational amplifier is configured to output a second logic level when the amplitude of the processed sampled signal is less than or equal to the amplitude of the preset threshold electrical signal. The first logic level and the second logic level are respectively transmitted to the input side of the corresponding isolation optocoupler, so as to obtain an output signal corresponding to the comparison result and achieving electrical isolation at the output side of the isolation optocoupler.

6. The design method for an adjustable high-precision sampling signal monitoring and protection circuit system according to claim 2, characterized in that, The precision reference source is a TL431 adjustable precision reference source, whose internal reference voltage It is 2.5V.

7. The design method for an adjustable high-precision sampling signal monitoring and protection circuit system according to claim 4, characterized in that, The instrumentation amplifier is an INA114 type instrumentation amplifier, with a preset gain setting resistor value inside. It is 50kΩ.

8. The design method for an adjustable high-precision sampling signal monitoring and protection circuit system according to claim 5, characterized in that, The output side of the isolation optocoupler is connected to a status indication circuit, which drives at least one light-emitting diode according to the output signal to provide a visual status indication corresponding to the comparison result.

9. An adjustable high-precision sampling signal monitoring and protection circuit system, characterized in that, include: The signal input and reference module is used to generate an adjustable threshold electrical signal; A high-precision differential amplifier module is used to perform differential amplification with adjustable gain on the signal to be measured collected from the power system, so as to output the processed sampled signal. The threshold comparison and isolation output module has its input terminals connected to the output terminals of the signal input and reference module and the high-precision differential amplifier module, respectively. It is used to compare the amplitude of the threshold electrical signal with the sampled signal and output the comparison result after electrical isolation. The display output and power supply module is used to provide operating power to each module and output the current set value of the threshold electrical signal to a display screen for display. The circuit parameters of the signal input and reference module, the high-precision differential amplifier module, and the threshold comparison and isolation output module are configured to be tuned by the design method described in any one of claims 1 to 8.

10. The adjustable high-precision sampling signal monitoring and protection circuit system according to claim 9, characterized in that, The circuit system is used for monitoring and protecting high-voltage pulse power supplies, which include laser xenon lamp driver power supplies or pulse power devices.

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