High-voltage signal sampling circuit
Patent Information
- Application Number
- CN202522025988.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-22
- Publication Date
- 2026-11-03
- Estimated Expiration
- 2035-09-22
AI Technical Summary
Existing high-voltage signal measurement equipment is expensive, making large-scale deployment difficult and keeping the cost of high-voltage signal measurement high.
The high-voltage signal sampling circuit adopts a modular design, including an input voltage divider module, an operational amplifier conditioning module, and an output impedance module. Through voltage division, in-phase amplification, differential processing, and impedance transformation, it realizes the voltage reduction, conditioning, and isolation output of high-voltage signals.
It effectively reduces the cost of high-voltage signal measurement, improves measurement accuracy and safety, enhances the circuit's adaptability in complex environments, prevents signal distortion and attenuation, and ensures the integrity and stability of signal transmission.
Smart Images
Figure CN224934060U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of electrical variable measurement technology, and more specifically, to a high-voltage signal sampling circuit. Background Technology
[0002] In recent years, the global energy transition has shifted towards cleaner energy, leading to an explosive growth in the market for new energy products such as photovoltaic inverters, energy storage converters, and new energy vehicle charging piles. Consequently, the demand for high-voltage, high-power signal measurement has increased dramatically.
[0003] Faced with the current huge market demand, specialized equipment for measuring high-voltage and high-power signals has emerged. For example, the new energy field currently mainly uses professional waveform recorders to measure high-voltage AC and DC signals. However, such equipment is often expensive, resulting in high costs for high-voltage signal measurement and making large-scale deployment difficult. Utility Model Content
[0004] The problem this invention addresses is how to reduce the cost of high-voltage signal measurement.
[0005] To address the aforementioned problems, this utility model provides a high-voltage signal sampling circuit, comprising an input voltage divider module, an operational amplifier conditioning module, and an output impedance module connected in sequence; the operational amplifier conditioning module includes a first operational amplifier, a second operational amplifier, a first feedback resistor, a second feedback resistor, and a differential amplifier unit; The input terminal of the input voltage divider module is adapted to be connected to the signal source under test, and the non-inverting input terminal of the first operational amplifier and the non-inverting input terminal of the second operational amplifier are respectively connected to the two output terminals of the input voltage divider module; One end of the first feedback resistor is connected to the negative input terminal of the first operational amplifier, and the other end is connected to the output terminal of the first operational amplifier; one end of the second feedback resistor is connected to the negative input terminal of the second operational amplifier, and the other end is connected to the output terminal of the second operational amplifier; the output terminals of the first operational amplifier and the second operational amplifier are respectively connected to the two input terminals of the differential amplifier unit. The input terminal of the output impedance module is connected to the output terminal of the differential amplifier unit, and the output terminal of the output impedance module is adapted to be connected to a measuring device.
[0006] Optionally, the operational amplifier conditioning module further includes a third feedback resistor; one end of the third feedback resistor is connected to the negative input terminal of the first operational amplifier, and the other end is connected to the negative input terminal of the second operational amplifier.
[0007] Optionally, the differential amplifier unit includes a fourth feedback resistor, a fifth feedback resistor, a sixth feedback resistor, and a differential amplifier; One end of the fourth feedback resistor is connected to the output terminal of the first operational amplifier, and the other end is connected to the non-inverting input terminal of the differential amplifier; one end of the fifth feedback resistor is connected to the output terminal of the second operational amplifier, and the other end is connected to the negative input terminal of the differential amplifier; one end of the sixth feedback resistor is connected to the negative input terminal of the differential amplifier, and the other end is connected to the output terminal of the differential amplifier; the output terminal of the differential amplifier is connected to the input terminal of the output impedance module.
[0008] Optionally, the differential amplifier unit further includes a seventh feedback resistor; one end of the seventh feedback resistor is connected to the non-inverting input terminal of the differential amplifier, and the other end is grounded.
[0009] Optionally, the operational amplifier conditioning module further includes a plurality of first capacitors connected in parallel with the first feedback resistor, the second feedback resistor, the third feedback resistor, the fourth feedback resistor, the fifth feedback resistor, the sixth feedback resistor, and the seventh feedback resistor.
[0010] Optionally, the output impedance module includes a compensation resistor and a compensation capacitor connected in parallel; one end of the compensation resistor and the compensation capacitor connected in parallel is connected to the output terminal of the differential amplifier unit, and the other end of the parallel connection is adapted to be connected to the measuring device.
[0011] Optionally, the time constant determined by the compensation resistor and the compensation capacitor is matched with the time constant determined by the input resistance and the input capacitance of the measuring device.
[0012] Optionally, the input voltage divider module includes a first voltage divider resistor, a second voltage divider resistor, a third voltage divider resistor, and a fourth voltage divider resistor; One end of the first voltage divider resistor is adapted to be connected to the signal source under test, and the other end is connected to the third voltage divider resistor. The first connection point between the first voltage divider resistor and the third voltage divider resistor is connected to the non-inverting input terminal of the first operational amplifier. One end of the second voltage divider resistor is adapted to be connected to the signal source under test, and the other end is connected to the fourth voltage divider resistor. The second connection point between the second voltage divider resistor and the fourth voltage divider resistor is connected to the non-inverting input terminal of the second operational amplifier. The end of the third voltage divider resistor furthest from the first connection point is connected to the end of the fourth voltage divider resistor furthest from the second connection point and grounded.
[0013] Optionally, the input voltage divider module further includes a first high-voltage capacitor connected in parallel with the first voltage divider resistor, and a second high-voltage capacitor connected in parallel with the second voltage divider resistor.
[0014] Optionally, the input impedance of the first operational amplifier is greater than the resistance of the third voltage divider resistor, and the input impedance of the second operational amplifier is greater than the resistance of the fourth voltage divider resistor.
[0015] This utility model's high-voltage signal sampling circuit adopts a modular design, including an input voltage divider module, an operational amplifier conditioning module, and an output impedance module connected in sequence. These modules work together to achieve voltage reduction, conditioning, and isolation of the high-voltage signal. First, by setting up the input voltage divider module, the high-voltage signal (i.e., the signal source under test) is attenuated to a low-voltage signal suitable for subsequent processing at a fixed ratio. This effectively isolates the high-voltage hazard source, preventing damage or safety accidents caused by high voltage directly entering sensitive electronic devices, significantly improving the safety and long-term reliability of the entire sampling system. Second, the operational amplifier conditioning module uses a dual-channel independent operational amplifier structure (i.e., a first operational amplifier and a second operational amplifier) to amplify the voltage-divided differential signal in phase, and corresponding first and second feedback resistors are configured for gain adjustment. This improves the symmetry of the two signals, providing high-quality input for subsequent differential processing and effectively improving overall measurement accuracy. Based on this, the output terminals of the first and second operational amplifiers are connected to the two input terminals of the differential amplifier unit, respectively. The differential amplifier unit performs differential processing on the conditioned dual-ended signal, effectively suppressing common-mode noise (such as power frequency interference, power fluctuations, and electromagnetic radiation), significantly improving the circuit's common-mode rejection ratio, ensuring accurate extraction of useful signals even in complex electromagnetic environments, and enhancing the circuit's adaptability to harsh environments such as industrial sites. Finally, the input terminal of the output impedance module in this invention is connected to the output terminal of the differential amplifier unit, and the output terminal is suitable for connecting to a measuring device. By setting the output impedance module, the output signal of the differential amplifier unit undergoes impedance transformation, providing a low-impedance buffered output, enhancing the circuit's ability to drive subsequent measuring devices, and helping to prevent signal distortion or attenuation caused by load changes, thus improving the integrity and stability of signal transmission.
[0016] Thus, in practical use, one end of the high-voltage signal sampling circuit is connected to the signal source under test, and the other end is connected to a measuring device (such as an oscilloscope). The high-voltage signal is sampled sequentially through the input voltage divider module, the operational amplifier conditioning module, and the output impedance module, and finally output to the measuring device for measurement. Through the modular design of the high-voltage signal sampling circuit in this invention, combined with the negative feedback mechanism and differential architecture, linear, stable, and low-distortion sampling of high-voltage signals is achieved, effectively reducing the cost of high-voltage signal measurement. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the high-voltage signal sampling circuit according to an embodiment of the present invention.
[0018] Explanation of reference numerals in the attached figures: Rk1 - First feedback resistor; Rk2 - Second feedback resistor; Rk3 - Third feedback resistor; Rk4 - Fourth feedback resistor; Rk5 - Fifth feedback resistor; Rk6 - Sixth feedback resistor; Rk7 - Seventh feedback resistor; OP1 - First operational amplifier; OP2 - Second operational amplifier; OP3 - Differential amplifier; Rb - Compensation resistor; Cb - Compensation capacitor; Rf1 - First voltage divider resistor; Rf2 - Second voltage divider resistor; Rf3 - Third voltage divider resistor; Rf4 - Fourth voltage divider resistor; Uin - Input terminal of the input voltage divider module; Uo - Output terminal of the output impedance module. Detailed Implementation
[0019] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Although some embodiments of this utility model are shown in the drawings, it should be understood that this utility model can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this utility model. It should be understood that the drawings and embodiments of this utility model are for illustrative purposes only and are not intended to limit the scope of protection of this utility model.
[0020] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first", "second", etc., mentioned in this utility model are only used to distinguish different devices, modules, or units, and are not used to limit the order of functions performed by these devices, modules, or units or their interdependencies.
[0021] It should be noted that the terms "a" and "a plurality of" used in this utility model are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".
[0022] like Figure 1 As shown, this utility model provides a high-voltage signal sampling circuit, including an input voltage divider module, an operational amplifier conditioning module, and an output impedance module connected in sequence; the operational amplifier conditioning module includes a first operational amplifier OP1, a second operational amplifier OP2, a first feedback resistor Rk1, a second feedback resistor Rk2, and a differential amplifier unit; The input terminal of the input voltage divider module is suitable for connecting to the signal source under test. The non-inverting input terminal of the first operational amplifier OP1 and the non-inverting input terminal of the second operational amplifier OP2 are respectively connected to the two output terminals of the input voltage divider module. One end of the first feedback resistor Rk1 is connected to the negative input terminal of the first operational amplifier OP1, and the other end is connected to the output terminal of the first operational amplifier OP1; one end of the second feedback resistor Rk2 is connected to the negative input terminal of the second operational amplifier OP2, and the other end is connected to the output terminal of the second operational amplifier OP2; the output terminals of the first operational amplifier OP1 and the second operational amplifier OP2 are respectively connected to the two input terminals of the differential amplifier unit. The input terminal of the output impedance module is connected to the output terminal of the differential amplifier unit, and the output terminal of the output impedance module is suitable for connecting to a measuring device.
[0023] Specifically, in this embodiment, the input terminal of the input voltage divider module is adapted to connect to the high-voltage signal source under test. When it is necessary to measure the signal source under test (such as the bus voltage in a power system or the high-level signal at the output of a frequency converter), the input terminal of the input voltage divider module can be connected to the high-voltage signal source under test to achieve voltage reduction and output to the subsequent operational amplifier conditioning module. For example, in this embodiment, the input voltage divider module can be composed of two or more resistors connected in series to form a resistor voltage divider network. When the high-voltage signal under test is connected, the voltage divider network can generate differential voltage signals with reduced amplitude and fixed ratio at its two output terminals, which are then output to the non-inverting input terminals of the first operational amplifier OP1 and the second operational amplifier OP2, respectively.
[0024] Furthermore, in this embodiment, the operational amplifier conditioning module includes a first operational amplifier OP1, a second operational amplifier OP2, a first feedback resistor Rk1, a second feedback resistor Rk2, and a differential amplifier unit. One end of the first feedback resistor Rk1 is connected to the negative input terminal of the first operational amplifier OP1, and the other end is connected to the output terminal of the first operational amplifier OP1. That is, the first feedback resistor Rk1 is connected between the negative input terminal and the output terminal of the first operational amplifier OP1, forming a negative feedback loop to stabilize the gain and improve the input impedance. Similarly, one end of the second feedback resistor Rk2 is connected to the negative input terminal of the second operational amplifier OP2, and the other end is connected to the output terminal of the second operational amplifier OP2. That is, the second feedback resistor Rk2 is connected between the negative input terminal and the output terminal of the second operational amplifier OP2, also forming a negative feedback loop to stabilize the gain and improve the input impedance.
[0025] In this embodiment, the first operational amplifier OP1 and its corresponding first feedback resistor Rk1 form one non-inverting proportional amplifier circuit, and the second operational amplifier OP2 and its corresponding second feedback resistor Rk2 form another non-inverting proportional amplifier circuit. By setting appropriate values for the first feedback resistor Rk1 and the second feedback resistor Rk2, the gain of the two differential signals can be independently adjusted to compensate for signal mismatch caused by slight differences in the voltage divider resistors or asymmetrical wiring, thereby improving common-mode rejection capability. Simultaneously, the output terminals of the first operational amplifier OP1 and the second operational amplifier OP2 are connected to the two input terminals of the differential amplifier unit, respectively. This allows the two differential signals, after being stepped down by the input voltage divider module, to undergo independent gain adjustment through two amplifier circuits, and the conditioned signals are then sent to the differential amplifier unit to extract the difference between the two signals. In this embodiment, the differential amplifier unit can be composed of a differential amplifier OP3 and its peripheral resistor network, converting the dual-ended input signal output from the operational amplifier conditioning module into a single-ended output signal, effectively suppressing common-mode signals such as power frequency interference and electromagnetic noise, which is beneficial for improving the signal-to-noise ratio and measurement accuracy.
[0026] Furthermore, the input terminal of the output impedance module is connected to the output terminal of the differential amplifier unit, and the output terminal of the output impedance module is suitable for connecting to an external measuring device (such as an oscilloscope). In practical use, the signal output by the operational amplifier conditioning module is output to the external measuring device through the output impedance module, which helps to reduce the influence of high-frequency noise and also provides electrical isolation, further protecting sensitive downstream devices (such as oscilloscopes) from the influence of abnormal voltages at the front end. For example, in this embodiment, the output impedance module can be implemented using an RC circuit.
[0027] In this embodiment, the high-voltage signal sampling circuit adopts a modular design, including an input voltage divider module, an operational amplifier conditioning module, and an output impedance module connected in sequence. These modules work together to achieve voltage reduction, conditioning, and isolation of the high-voltage signal. First, by setting up the input voltage divider module, the high-voltage signal (i.e., the signal source under test) is attenuated to a low-voltage signal suitable for subsequent processing at a fixed ratio. This effectively isolates the high-voltage hazard source, preventing damage or safety accidents caused by high voltage directly entering sensitive electronic devices, significantly improving the safety and long-term reliability of the entire sampling system. Second, the operational amplifier conditioning module uses a dual-channel independent operational amplifier structure (i.e., the first operational amplifier OP1 and the second operational amplifier OP2) to amplify the differential signal after voltage division in phase, and configures corresponding first feedback resistors Rk1 and second feedback resistors Rk2 for gain adjustment. This helps improve the symmetry of the two signals, providing high-quality input for subsequent differential processing and effectively improving the overall measurement accuracy. Based on this, the output terminals of the first operational amplifier OP1 and the second operational amplifier OP2 are respectively connected to the two input terminals of the differential amplifier unit. The differential amplifier unit performs differential processing on the conditioned dual-ended signal, effectively suppressing common-mode noise (such as power frequency interference, power fluctuations, electromagnetic radiation, etc.), significantly improving the circuit's common-mode rejection ratio, ensuring accurate extraction of useful signals even in complex electromagnetic environments, and enhancing the circuit's adaptability to harsh environments such as industrial sites. Finally, in this embodiment, the input terminal of the output impedance module is connected to the output terminal of the differential amplifier unit, and the output terminal is suitable for connecting to a measuring device. By setting the output impedance module, the output signal of the differential amplifier unit undergoes impedance transformation, providing a low-impedance buffered output, enhancing the circuit's ability to drive subsequent measuring devices, and helping to prevent signal distortion or attenuation caused by load changes, thus improving the integrity and stability of signal transmission.
[0028] Thus, in practical use, one end of the high-voltage signal sampling circuit is connected to the signal source under test, and the other end is connected to a measuring device (such as an oscilloscope). The high-voltage signal is sampled sequentially through the input voltage divider module, the operational amplifier conditioning module, and the output impedance module, and finally output to the measuring device for measurement. Through the modular design of the high-voltage signal sampling circuit in this embodiment, combined with the negative feedback mechanism and differential architecture, linear, stable, and low-distortion sampling of the high-voltage signal is achieved, effectively reducing the cost of high-voltage signal measurement.
[0029] Optionally, such as Figure 1 As shown, the operational amplifier conditioning module also includes a third feedback resistor Rk3; one end of the third feedback resistor Rk3 is connected to the negative input terminal of the first operational amplifier OP1, and the other end is connected to the negative input terminal of the second operational amplifier OP2.
[0030] Specifically, in this embodiment, the operational amplifier conditioning module further includes a third feedback resistor Rk3. One end of the third feedback resistor Rk3 is connected to the negative input terminal of the first operational amplifier OP1, and the other end is connected to the negative input terminal of the second operational amplifier OP2, thereby forming a cross-feedback path between the inverting input terminals of the two operational amplifiers. The third feedback resistor Rk3, together with the first feedback resistor Rk1 and the second feedback resistor Rk2, constitutes a balanced differential input conditioning network, which helps to reduce gain mismatch and offset errors caused by the dispersion of device parameters (such as differences in operational amplifier input bias current, resistance tolerance, etc.). In this embodiment, the resistance value of the third feedback resistor Rk3 can be matched with the first feedback resistor Rk1 and the second feedback resistor Rk2, which helps to ensure the symmetry of the circuit.
[0031] In this embodiment, the first operational amplifier OP1 and its first feedback resistor Rk1 form a non-inverting amplifier circuit, the second operational amplifier OP2 and its second feedback resistor Rk2 form another non-inverting amplifier circuit, and the third feedback resistor Rk3 couples the negative input terminals of both. When there is a slight deviation between the two differential signals output by the input voltage divider module or when external asymmetric interference is introduced, the third feedback resistor Rk3 can automatically adjust the potential relationship between the inverting terminals of the two operational amplifiers through a negative feedback mechanism, suppressing common-mode voltage drift and enhancing the dynamic matching capability between the two amplification channels.
[0032] Optionally, such as Figure 1 As shown, the differential amplifier unit includes a fourth feedback resistor Rk4, a fifth feedback resistor Rk5, a sixth feedback resistor Rk6, and a differential amplifier OP3; One end of the fourth feedback resistor Rk4 is connected to the output terminal of the first operational amplifier OP1, and the other end is connected to the non-inverting input terminal of the differential amplifier OP3; one end of the fifth feedback resistor Rk5 is connected to the output terminal of the second operational amplifier OP2, and the other end is connected to the negative input terminal of the differential amplifier OP3; one end of the sixth feedback resistor Rk6 is connected to the negative input terminal of the differential amplifier OP3, and the other end is connected to the output terminal of the differential amplifier OP3; the output terminal of the differential amplifier OP3 is connected to the input terminal of the output impedance module.
[0033] Specifically, in this embodiment, the differential amplifier unit includes a fourth feedback resistor Rk4, a fifth feedback resistor Rk5, a sixth feedback resistor Rk6, and a differential amplifier OP3. One end of the fourth feedback resistor Rk4 is connected to the output of the first operational amplifier OP1, and the other end is connected to the non-inverting input of the differential amplifier OP3. One end of the fifth feedback resistor Rk5 is connected to the output of the second operational amplifier OP2, and the other end is connected to the negative input of the differential amplifier OP3. The sixth feedback resistor Rk6 is connected between the negative input and output of the differential amplifier OP3, forming a negative feedback loop. The output of the differential amplifier OP3 is connected to the input of the output impedance module, transmitting the conditioned signal to an external measuring device.
[0034] In this embodiment, differential amplifier OP3 receives two conditioned differential signals output from the operational amplifier conditioning module through the fourth feedback resistor Rk4 and the fifth feedback resistor Rk5, respectively. Since the first operational amplifier OP1 and the second operational amplifier OP2 of the operational amplifier conditioning module have performed in-phase amplification and impedance isolation on the original voltage divider signals, the signal input to this stage of differential amplifier OP3 has high driving capability and good matching. Differential amplifier OP3 utilizes its inherent differential input characteristics to amplify only the voltage difference between the two input signals while suppressing their common-mode components (such as power supply noise and ground interference).
[0035] Furthermore, in this embodiment, the negative feedback network formed by the sixth feedback resistor Rk6 and the differential amplifier OP3 can set the closed-loop gain of the differential amplifier OP3, ensuring a linear and stable proportional relationship between the output signal and the input differential voltage. In practical applications, the voltage gain of the entire differential amplifier unit can be precisely controlled by appropriately selecting the resistance ratios of the fourth feedback resistor Rk4, the fifth feedback resistor Rk5, and the sixth feedback resistor Rk6, thereby meeting the signal amplitude matching requirements in different application scenarios.
[0036] Optionally, such as Figure 1 As shown, the differential amplifier unit also includes a seventh feedback resistor Rk7; one end of the seventh feedback resistor Rk7 is connected to the non-inverting input terminal of the differential amplifier OP3, and the other end is grounded.
[0037] Specifically, in this embodiment, the differential amplifier unit also includes a seventh feedback resistor Rk7. By connecting the seventh feedback resistor Rk7 between the non-inverting input terminal of the differential amplifier OP3 and ground, a stable discharge path is provided for the input bias current, ensuring that the non-inverting input terminal of the differential amplifier OP3 has a defined reference potential under static conditions. Simultaneously, the seventh feedback resistor Rk7 helps balance the equivalent impedance of the two input terminals of the differential amplifier OP3: when the negative input terminal is connected to the output terminal through the sixth feedback resistor Rk6, its AC and DC impedance characteristics are relatively clear; however, if the non-inverting input terminal is in a high-impedance floating state, it may lead to impedance mismatch, introducing additional common-mode to differential-mode error. By setting the seventh feedback resistor Rk7, the equivalent input impedance of the non-inverting input terminal can be better matched with that of the negative input terminal, thereby reducing offset error and improving the symmetry and stability of the entire differential amplifier circuit.
[0038] In this embodiment, the seventh feedback resistor Rk7, which is connected to the non-inverting input of the differential amplifier OP3 at one end and grounded at the other end, makes the equivalent impedance of the non-inverting input more clearly defined. This helps to match the impedance network formed by the fifth feedback resistor Rk5 and the sixth feedback resistor Rk6 at the negative input, reducing the conversion of common-mode signals to differential-mode signals and further improving the common-mode rejection ratio of the circuit.
[0039] Optionally, such as Figure 1 As shown, the operational amplifier conditioning module also includes multiple first capacitors connected in parallel with the first feedback resistor Rk1, the second feedback resistor Rk2, the third feedback resistor Rk3, the fourth feedback resistor Rk4, the fifth feedback resistor Rk5, the sixth feedback resistor Rk6, and the seventh feedback resistor Rk7.
[0040] Specifically, in this embodiment, the operational amplifier conditioning module also includes multiple first capacitors connected in parallel with the first feedback resistor Rk1, the second feedback resistor Rk2, the third feedback resistor Rk3, the fourth feedback resistor Rk4, the fifth feedback resistor Rk5, the sixth feedback resistor Rk6, and the seventh feedback resistor Rk7. That is, each feedback resistor can be connected in parallel with an additional capacitor to achieve a low-pass filtering effect. In this embodiment, each first capacitor and its corresponding feedback resistor together constitute a low-pass filter, and its cutoff frequency can be selected according to the bandwidth of the measured signal and the anti-interference requirements. In practical use, by reasonably selecting the capacitance value of the first capacitor (e.g., a 0.1μF or 1nF ceramic capacitor), high-frequency components can be effectively attenuated without affecting the main signal transmission, thereby improving the signal-to-noise ratio and operational stability of each amplification stage.
[0041] In this embodiment, a first capacitor is connected in parallel across the first feedback resistor Rk1 to form a local filter network for the first feedback loop; another first capacitor is connected in parallel across the second feedback resistor Rk2 to form a filter structure for the second feedback loop; and yet another first capacitor is connected in parallel across the third feedback resistor Rk3, which helps to suppress high-frequency interference coupled between the negative input terminals of the first operational amplifier OP1 and the second operational amplifier OP2.
[0042] Similarly, a first capacitor connected in parallel across the fourth feedback resistor Rk4 helps filter out high-frequency noise transmitted from the output of the first operational amplifier OP1 to the non-inverting input of the differential amplifier OP3; a first capacitor connected in parallel across the fifth feedback resistor Rk5 reduces the impact of spikes in the output signal of the second operational amplifier OP2 on the negative input of the differential amplifier OP3; a first capacitor connected in parallel across the sixth feedback resistor Rk6 forms a phase compensation network for the feedback path of the differential amplifier OP3, helping to improve loop stability and prevent high-frequency oscillations. Furthermore, a first capacitor connected in parallel across the seventh feedback resistor Rk7 limits the frequency characteristics of the AC impedance to ground at the non-inverting input of the differential amplifier OP3, suppressing high-frequency common-mode noise from coupling into sensitive input nodes through this path.
[0043] Optionally, such as Figure 1 As shown, the output impedance module includes a compensation resistor Rb and a compensation capacitor Cb connected in parallel; one end of the compensation resistor Rb and the compensation capacitor Cb connected in parallel is connected to the output terminal of the differential amplifier unit, and the other end of the parallel connection is suitable for connecting to a measuring device.
[0044] Specifically, in this embodiment, the output impedance module includes a compensation resistor Rb and a compensation capacitor Cb connected in parallel. One end of the compensation resistor Rb and the compensation capacitor Cb connected in parallel is connected to the output terminal of the differential amplifier unit. When it is necessary to measure the high voltage signal using a high voltage signal acquisition circuit and a measuring device, the other end of the compensation resistor Rb and the compensation capacitor Cb connected in parallel can be connected to the measuring device.
[0045] In this embodiment, the compensation resistor Rb and the compensation capacitor Cb are connected in parallel to the output path of the circuit to adjust the output characteristics of the output impedance module. The compensation resistor Rb provides a stable DC path and a defined output impedance value, ensuring the output signal has good load-carrying capacity and preventing signal attenuation caused by changes in the input impedance of the subsequent measurement device. The compensation capacitor Cb exhibits low impedance characteristics to high-frequency components, absorbing high-frequency noise spikes in the output signal, suppressing signal reflection and ringing, and improving the integrity of the signal's rising and falling edges.
[0046] Optionally, the time constants determined by the compensation resistor Rb and the compensation capacitor Cb are matched with the time constants determined by the input resistance and the input capacitance of the measuring device.
[0047] Specifically, when the signal source under test is turned on, current flows through the compensation resistor Rb to charge the compensation capacitor Cb, and the voltage across the compensation capacitor Cb gradually increases. When the signal source under test is turned off or the voltage changes, the compensation capacitor Cb discharges through the compensation resistor Rb, and the voltage gradually decreases. In this embodiment, the resistance value of the compensation resistor Rb and the capacitance of the compensation capacitor Cb together determine the charging and discharging speed, and their product is the time constant. Similarly, when the output impedance module outputs a signal to an external measuring device, the input terminal of the measuring device typically includes its own input resistance and input capacitance, which together determine the time constant of the measuring device. In the output compensation module, compensation can be achieved by using a compensation resistor Rb in parallel with a compensation capacitor Cb, based on the input impedance (i.e., input resistance and input capacitance) of different external measuring devices (such as oscilloscopes). For example, suppose an oscilloscope has an input resistance of 1MΩ and an input capacitance of 12pF. Although its nominal bandwidth can reach 20MHz, in actual measurement, phase deviation may occur when the input signal reaches 1MHz. A compensation resistor Rb with the same resistance value (such as 1MΩ) and a compensation capacitor Cb with the same capacitance (such as 12pF) can be connected in parallel to compensate for the phase.
[0048] In this embodiment, by appropriately selecting the resistance value of the compensation resistor Rb and the capacitance value of the compensation capacitor Cb, the time constants determined by the compensation resistor Rb and the compensation capacitor Cb are made equal to or approximately equal to (i.e., matched) the time constants determined by the input resistance and output capacitance of the measuring device, thereby achieving matching of the signal path in terms of dynamic response characteristics. This ensures that the frequency response of the signal output from the high-voltage signal sampling circuit remains consistent during transmission to the measuring device, avoiding problems such as signal waveform distortion, phase shift, or amplitude attenuation that occur when the output of the differential amplifier OP3 is directly connected to the measuring device.
[0049] Optionally, such as Figure 1 As shown, the input voltage divider module includes a first voltage divider resistor Rf1, a second voltage divider resistor Rf2, a third voltage divider resistor Rf3, and a fourth voltage divider resistor Rf4; One end of the first voltage divider resistor Rf1 is suitable for connecting to the signal source under test, and the other end is connected to the third voltage divider resistor Rf3. The first connection point of the first voltage divider resistor Rf1 and the third voltage divider resistor Rf3 is connected to the non-inverting input terminal of the first operational amplifier OP1. One end of the second voltage divider resistor Rf2 is suitable for connecting to the signal source under test, and the other end is connected to the fourth voltage divider resistor Rf4. The second connection point of the second voltage divider resistor Rf2 and the fourth voltage divider resistor Rf4 is connected to the non-inverting input terminal of the second operational amplifier OP2. The end of the third voltage divider resistor Rf3 furthest from the first connection point is connected to the end of the fourth voltage divider resistor Rf4 furthest from the second connection point and grounded.
[0050] Specifically, in this embodiment, the input voltage divider module includes a first voltage divider resistor Rf1, a second voltage divider resistor Rf2, a third voltage divider resistor Rf3, and a fourth voltage divider resistor Rf4. One end of the first voltage divider resistor Rf1 is adapted to connect to the signal source under test, and the other end is connected to the third voltage divider resistor Rf3. A first connection point is formed between the first voltage divider resistor Rf1 and the third voltage divider resistor Rf3, and this first connection point is connected to the non-inverting input terminal of the first operational amplifier OP1. Furthermore, one end of the second voltage divider resistor Rf2 is adapted to connect to the signal source under test, and the other end is connected to the fourth voltage divider resistor Rf4. A second connection point is formed between the second voltage divider resistor Rf2 and the fourth voltage divider resistor Rf4, and this second connection point is connected to the non-inverting input terminal of the second operational amplifier OP2. Simultaneously, the end of the third voltage divider resistor Rf3 furthest from the first connection point and the end of the fourth voltage divider resistor Rf4 furthest from the second connection point are connected and grounded together.
[0051] Optionally, in this embodiment, the resistance values of the first voltage divider resistor Rf1 and the second voltage divider resistor Rf2 are equal, and the resistance values of the third voltage divider resistor Rf3 and the fourth voltage divider resistor Rf4 are equal. This helps to ensure that the voltage division ratios of the two circuits are consistent, and further improves the symmetry of the circuit and the accuracy of the measurement.
[0052] In this embodiment, the first voltage divider resistor Rf1 and the third voltage divider resistor Rf3 form one series voltage divider branch, and the second voltage divider resistor Rf2 and the fourth voltage divider resistor Rf4 form another series voltage divider branch. The two voltage divider branches proportionally attenuate the measured high-voltage signal, outputting a differential voltage signal with reduced amplitude at the first connection point and the second connection point. By grounding the ends of the third voltage divider resistor Rf3 and the fourth voltage divider resistor Rf4 together, a unified reference potential is ensured for the two voltage divider circuits, avoiding common-mode voltage deviation caused by ground wire separation or potential drift. Simultaneously, this symmetrical dual-branch structure helps improve the matching degree of the two output signals, providing balanced differential input conditions for the subsequent operational amplifier conditioning module.
[0053] Optionally, the input voltage divider module further includes a first high-voltage capacitor connected in parallel with the first voltage divider resistor Rf1, and a second high-voltage capacitor connected in parallel with the second voltage divider resistor Rf2.
[0054] Specifically, in this embodiment, the input voltage divider module also includes a first high-voltage capacitor connected in parallel with the first voltage divider resistor Rf1, and a second high-voltage capacitor connected in parallel with the second voltage divider resistor Rf2. Since the first high-voltage capacitor is connected in parallel across the first voltage divider resistor Rf1, and one end of the first voltage divider resistor Rf1 is suitable for connecting to the high-voltage signal source being measured, this capacitor needs to withstand high voltage stress. Similarly, the second high-voltage capacitor is connected in parallel across the second voltage divider resistor Rf2, and is also in a high-voltage operating environment. To ensure long-term safe and reliable operation, the first and second high-voltage capacitors can be high-voltage capacitors with high withstand voltage ratings, such as ceramic high-voltage capacitors, which possess good insulation performance, low dielectric loss, and excellent temperature stability.
[0055] In this embodiment, the first high-voltage capacitor and the second high-voltage capacitor not only withstand high voltage, but also have excellent high-frequency response characteristics. The RC network formed by them, together with the first voltage divider resistor Rf1 and the second voltage divider resistor Rf2, can provide controllable phase lag or lead in the high-frequency band to compensate for the phase shift caused by parasitic inductance or op-amp input capacitance in the signal path, thereby improving the timing consistency of the two differential signals.
[0056] Optionally, the input impedance of the first operational amplifier OP1 is greater than the resistance of the third voltage divider resistor Rf3, and the input impedance of the second operational amplifier OP2 is greater than the resistance of the fourth voltage divider resistor Rf4.
[0057] Specifically, in this embodiment, the input impedance of the first operational amplifier OP1 is greater than the resistance of the third voltage divider resistor Rf3, and the input impedance of the second operational amplifier OP2 is greater than the resistance of the fourth voltage divider resistor Rf4. That is, both the first operational amplifier OP1 and the second operational amplifier OP2 have high input impedance characteristics, which helps ensure that the current flowing into the input terminals of the operational amplifiers is small, and almost no current is drawn from the voltage divider nodes. In this embodiment, the resistance values of the third voltage divider resistor Rf3 and the fourth voltage divider resistor Rf4 can be determined based on the input impedances of the first operational amplifier OP1 and the second operational amplifier OP2. The input impedances of the first operational amplifier OP1 and the second operational amplifier OP2 are divided into common-mode input impedance and differential-mode input impedance. The common-mode input impedance refers to the impedance presented by each input terminal of the operational amplifier to ground (or power supply), often reaching tens of megaohms. The differential-mode input impedance refers to the impedance presented between the two input terminals of the operational amplifier, generally above 1 megaohm. The third voltage divider resistor Rf3 and the fourth voltage divider resistor Rf4 can be selected with a resistance value of less than 50 kΩ. This ensures that the operational amplifier has high input impedance characteristics while also helping to avoid the first voltage divider resistor Rf1 and the second voltage divider resistor Rf2 having excessively high resistance values.
[0058] Thus, in this embodiment, the voltage at the first connection point can be determined by the resistance ratio of the first voltage divider resistor Rf1 to the third voltage divider resistor Rf3. Similarly, the voltage at the second connection point can be determined by the resistance ratio of the second voltage divider resistor Rf2 to the fourth voltage divider resistor Rf4. This will not cause a significant shift due to the connection of an operational amplifier, ensuring that the differential voltage signal output from the input voltage divider module truly reflects the proportional relationship of the measured high-voltage signal.
[0059] Although the present invention has been disclosed above, its protection scope 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 protection scope of the present invention.
Claims
1. A high-voltage signal sampling circuit, characterized in that, It includes an input voltage divider module, an operational amplifier conditioning module, and an output impedance module connected in sequence; the operational amplifier conditioning module includes a first operational amplifier, a second operational amplifier, a first feedback resistor, a second feedback resistor, and a differential amplifier unit; The input terminal of the input voltage divider module is adapted to be connected to the signal source under test, and the non-inverting input terminal of the first operational amplifier and the non-inverting input terminal of the second operational amplifier are respectively connected to the two output terminals of the input voltage divider module; One end of the first feedback resistor is connected to the negative input terminal of the first operational amplifier, and the other end is connected to the output terminal of the first operational amplifier; one end of the second feedback resistor is connected to the negative input terminal of the second operational amplifier, and the other end is connected to the output terminal of the second operational amplifier; the output terminals of the first operational amplifier and the second operational amplifier are respectively connected to the two input terminals of the differential amplifier unit. The input terminal of the output impedance module is connected to the output terminal of the differential amplifier unit, and the output terminal of the output impedance module is adapted to be connected to a measuring device.
2. The high-voltage signal sampling circuit according to claim 1, characterized in that, The operational amplifier conditioning module further includes a third feedback resistor; one end of the third feedback resistor is connected to the negative input terminal of the first operational amplifier, and the other end is connected to the negative input terminal of the second operational amplifier.
3. The high-voltage signal sampling circuit according to claim 2, characterized in that, The differential amplifier unit includes a fourth feedback resistor, a fifth feedback resistor, a sixth feedback resistor, and a differential amplifier; One end of the fourth feedback resistor is connected to the output terminal of the first operational amplifier, and the other end is connected to the non-inverting input terminal of the differential amplifier; one end of the fifth feedback resistor is connected to the output terminal of the second operational amplifier, and the other end is connected to the negative input terminal of the differential amplifier; one end of the sixth feedback resistor is connected to the negative input terminal of the differential amplifier, and the other end is connected to the output terminal of the differential amplifier; the output terminal of the differential amplifier is connected to the input terminal of the output impedance module.
4. The high-voltage signal sampling circuit according to claim 3, characterized in that, The differential amplifier unit also includes a seventh feedback resistor; one end of the seventh feedback resistor is connected to the non-inverting input terminal of the differential amplifier, and the other end is grounded.
5. The high-voltage signal sampling circuit according to claim 4, characterized in that, The operational amplifier conditioning module also includes a plurality of first capacitors connected in parallel with the first feedback resistor, the second feedback resistor, the third feedback resistor, the fourth feedback resistor, the fifth feedback resistor, the sixth feedback resistor, and the seventh feedback resistor.
6. The high-voltage signal sampling circuit according to claim 1, characterized in that, The output impedance module includes a compensation resistor and a compensation capacitor connected in parallel; one end of the compensation resistor and the compensation capacitor connected in parallel is connected to the output terminal of the differential amplifier unit, and the other end of the parallel connection is adapted to be connected to the measuring device.
7. The high-voltage signal sampling circuit according to claim 6, characterized in that, The time constants determined by the compensation resistor and the compensation capacitor are matched with the time constants determined by the input resistance and the input capacitance of the measuring device.
8. The high-voltage signal sampling circuit according to claim 1, characterized in that, The input voltage divider module includes a first voltage divider resistor, a second voltage divider resistor, a third voltage divider resistor, and a fourth voltage divider resistor; One end of the first voltage divider resistor is adapted to be connected to the signal source under test, and the other end is connected to the third voltage divider resistor. The first connection point between the first voltage divider resistor and the third voltage divider resistor is connected to the non-inverting input terminal of the first operational amplifier. One end of the second voltage divider resistor is adapted to be connected to the signal source under test, and the other end is connected to the fourth voltage divider resistor. The second connection point between the second voltage divider resistor and the fourth voltage divider resistor is connected to the non-inverting input terminal of the second operational amplifier. The end of the third voltage divider resistor furthest from the first connection point is connected to the end of the fourth voltage divider resistor furthest from the second connection point and grounded.
9. The high-voltage signal sampling circuit according to claim 8, characterized in that, The input voltage divider module further includes a first high-voltage capacitor connected in parallel with the first voltage divider resistor, and a second high-voltage capacitor connected in parallel with the second voltage divider resistor.
10. The high-voltage signal sampling circuit according to claim 8, characterized in that, The input impedance of the first operational amplifier is greater than the resistance of the third voltage divider resistor, and the input impedance of the second operational amplifier is greater than the resistance of the fourth voltage divider resistor.