Anti-common-mode interference isolation type AC high-voltage signal acquisition circuit

Abstract

The utility model discloses an anti-common-mode interference isolation type AC high-voltage signal acquisition circuit, and an isolation power supply module is an independent power supply for establishing electrical isolation between a high-voltage side circuit and a low-voltage side circuit. The input attenuation and clamping module carries out attenuation and amplitude clamping on a high-voltage side alternating current signal. And the isolation amplification and signal conversion module isolates and transmits the attenuated signal to a low-voltage side, and outputs a low-voltage analog signal taking the low-voltage side ground as a reference. And the buffering and filtering output module is used for buffering and filtering the signal, enhancing the driving capability, inhibiting noise and outputting a stable acquisition signal. According to the utility model, fault voltage and surge at a high-voltage side are effectively blocked through electrical isolation, personnel and equipment are protected, and the reliability, control precision and robustness of the system in a severe environment are improved in combination with signal conditioning.

Description

Technical Field

[0001] This utility model relates to the field of high-voltage electrical signal detection technology, and in particular to an isolated AC high-voltage signal acquisition circuit that resists common-mode interference. Background Technology

[0002] In the monitoring and control of industrial high-voltage equipment (such as crane motor rotor circuits and inverter buses), it is often necessary to collect high-voltage AC signals and send them to a low-voltage microcontroller (such as an MCU) for processing. Traditional high-voltage acquisition schemes typically use a resistor divider method for direct sampling, but this method has the following problems:

[0003] 1. Unequal high and low voltage ground potential

[0004] The ground (GND_HV) on the high-voltage side (such as the motor drive bus) and the ground (GND_LV) on the low-voltage side (such as the MCU) may not be at the same potential. Due to factors such as high current and long cables, GND_H may fluctuate drastically relative to GND_LV by tens, hundreds, or even thousands of volts. If not isolated, common-mode voltage will be introduced into the acquisition circuit, interfering with signal acquisition and even damaging the back-end circuitry.

[0005] 2. Noise and interference issues exist.

[0006] High-voltage environments are typically high-noise environments. This noise can couple into sensitive low-voltage side circuits through the power supply and ground wires, leading to a decrease in signal quality, a reduction in measurement accuracy, and even causing system malfunctions or crashes.

[0007] 3. Security issues

[0008] Any circuit directly connected to the high-voltage side, if its ground is connected to the earth or the equipment casing, may break down the sampling circuit and threaten the safety of the equipment and personnel if a fault occurs on the high-voltage side. Utility Model Content

[0009] This invention provides an isolated AC high-voltage signal acquisition circuit that resists common-mode interference, thereby overcoming the aforementioned technical problems.

[0010] To achieve the above objectives, the technical solution of this utility model is as follows:

[0011] An isolated AC high-voltage signal acquisition circuit with common-mode interference suppression includes: an isolation power supply module, an input attenuation and clamping module, an isolation amplification and signal conversion module, and a buffer and filter output module;

[0012] The output of the isolated power supply module is connected to the power input of the input attenuation and clamping module and the isolation amplification and signal conversion module, respectively. It is used to establish an independent working power reference that can electrically isolate the low-voltage side circuit from the high-voltage side circuit.

[0013] The input attenuation and clamping module is connected to the isolation amplification and signal conversion module, and it can obtain its own power supply from the isolation power supply module. At the same time, it attenuates the input high-voltage AC signal and limits the amplitude of the attenuated AC signal to a preset safe voltage range.

[0014] The isolation amplification and signal conversion module is used to isolate the attenuated AC signal on the high-voltage side and transmit it to the low-voltage side, thereby outputting a low-voltage analog signal with the low-voltage side ground as the reference potential.

[0015] The buffer and filter output module is connected to the isolation amplification and signal conversion module. It is used to buffer and filter the low-voltage analog signal to enhance its driving capability and suppress noise, thereby outputting a stable analog voltage signal as the acquisition signal.

[0016] Furthermore, the input attenuation and clamping module includes a first resistor, a second resistor, a third resistor, and a clamping diode;

[0017] One end of the first resistor is connected to the high-voltage AC input signal terminal, and the other end is connected to one end of the second resistor. The other end of the second resistor is connected to one end of the third resistor, and the other end of the third resistor is connected to the isolation amplification and signal conversion module.

[0018] The two ends of the clamping diode are connected to the +5V power supply and the isolation amplifier and signal conversion module, respectively.

[0019] Furthermore, the isolated power supply module includes an isolated power supply chip, a first capacitor, and a second capacitor;

[0020] The first pin of the isolation power chip is grounded, and the second pin is connected to a +24V power supply.

[0021] One end of the first capacitor is grounded, and the other end is connected to a +24V power supply;

[0022] The third pin of the isolation power chip is grounded, and the fourth pin is connected to the +5V power supply; one end of the second capacitor is grounded, and the other end is connected to the output terminal of the isolation power chip.

[0023] Furthermore, the isolation amplification and signal conversion module includes a first operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor, and a fourth capacitor;

[0024] The two power input terminals of the first operational amplifier are connected to a +5V and a +3.3V power supply, respectively;

[0025] The non-inverting input and inverting input of the first operational amplifier are respectively connected to the two ends of the sixth resistor, and the sixth resistor is connected to the clamping diode;

[0026] The output of the first operational amplifier is connected to the buffer and filter output module;

[0027] One end of the fifth resistor is connected to a +5V power supply, and the other end is connected to one end of the seventh resistor, with the other end of the seventh resistor grounded.

[0028] One end of the third capacitor is connected to a +5V power supply, and the other end is grounded.

[0029] One end of the fourth capacitor is connected to the sixth resistor, and the other end is grounded.

[0030] Furthermore, the buffer and filter output module includes a second operational amplifier, an eighth resistor, a fifth capacitor, a sixth capacitor, and a seventh capacitor;

[0031] The non-inverting input of the second operational amplifier is connected to the output of the first operational amplifier, and the inverting input is connected to its own output.

[0032] One end of the eighth resistor is connected to the output terminal of the second operational amplifier, and the other end is connected to the sixth capacitor. The power supply terminal of the second operational amplifier is connected to a +3.3V power supply.

[0033] One end of the fifth capacitor is connected to a +3.3V power supply, and the other end is grounded;

[0034] The other end of the sixth capacitor is grounded;

[0035] One end of the seventh capacitor is connected to a +3.3V power supply, and the other end is grounded;

[0036] One end of the eighth resistor is connected to the output signal terminal.

[0037] Furthermore, it also includes a high-impedance common-reference measurement front-end network connected to the input attenuation and clamping module, which is used to establish a reference for the high-voltage side AC signal;

[0038] The high-impedance common-reference measurement front-end network includes a ninth resistor, a tenth resistor, and an eleventh resistor;

[0039] One end of the ninth resistor is connected to the high-voltage AC input signal terminal, and its other end is connected to one end of the tenth resistor. The other end of the tenth resistor is connected to one end of the eleventh resistor, and the other end of the eleventh resistor is grounded.

[0040] Beneficial effects: This invention establishes a high-impedance barrier between high and low voltage through an isolated power supply module and an isolated amplification and signal conversion module. This effectively prevents fault voltages and surges from the high-voltage side from impacting the low-voltage side, protecting operators and core control equipment, and greatly enhancing the system's survivability and long-term reliability in harsh electrical environments. The buffering and filtering output module buffers and filters the low-voltage analog signal, resulting in a cleaner output signal and more stable and reliable readings, thereby improving the system's control accuracy and robustness. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the isolated AC high-voltage signal acquisition circuit in this utility model. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0044] This embodiment provides an isolated AC high-voltage signal acquisition circuit that resists common-mode interference, such as... Figure 1 As shown, it includes: an isolated power supply module, an input attenuation and clamping module, an isolated amplification and signal conversion module, and a buffer and filter output module;

[0045] The output of the isolated power supply module is connected to the power input of the input attenuation and clamping module and the isolation amplification and signal conversion module, respectively. It is used to establish an independent working power reference that can electrically isolate the low-voltage side circuit from the high-voltage side circuit.

[0046] The input attenuation and clamping module is connected to the isolation amplification and signal conversion module, and it can obtain its own power supply from the isolation power supply module. At the same time, it attenuates the input high-voltage AC signal and limits the amplitude of the attenuated AC signal to a preset safe voltage range.

[0047] Specifically, the input attenuation and clamping module is directly connected to the high-voltage signal source being measured. Through attenuation, the dangerous high-voltage signal is proportionally attenuated to a signal range that can be safely handled by the low-voltage side circuit. Through clamping, the voltage to ground of the attenuated signal is limited to the safe input voltage range of the subsequent circuit.

[0048] The isolation amplification and signal conversion module is used to isolate the attenuated AC signal on the high-voltage side and transmit it to the low-voltage side, thereby outputting a low-voltage analog signal with the low-voltage side ground as the reference potential.

[0049] The buffer and filter output module is connected to the isolation amplification and signal conversion module. It is used to buffer and filter the low-voltage analog signal to enhance its driving capability and suppress noise, thereby outputting a stable analog voltage signal as the acquisition signal.

[0050] In a specific embodiment, the input attenuation and clamping module includes a first resistor R59, a second resistor R60, a third resistor R61, and a clamping diode D13;

[0051] The first end of the first resistor R59 is connected to the high-voltage AC input signal terminal IN, and its other end is connected to one end of the second resistor R60. The other end of the second resistor R60 is connected to one end of the third resistor R61, and the other end of the third resistor R61 is connected to the isolation amplifier and signal conversion module.

[0052] The two ends of the clamping diode D13 are connected to the +5V power supply and the isolation amplifier and signal conversion module, respectively.

[0053] Specifically, the input attenuation and clamping module is responsible for safely attenuating the high-voltage signal to a low-voltage range and preventing overvoltage surges through clamping diode D13, thus protecting downstream devices. Specifically, clamping diode D13 is connected between the high-voltage network and the +5V isolation power supply. When the input AC signal changes periodically, whether it's the positive or negative half-cycle, one side of clamping diode D13 will conduct, thereby always maintaining a 5V voltage difference between the isolation power supply ground and the output pin.

[0054] In a specific embodiment, the isolated power supply module includes an isolated power chip U16, a first capacitor C64, and a second capacitor C66;

[0055] The first pin of the isolation power chip U16 is grounded, and the second pin is connected to the +24V power supply. One end of the first capacitor C64 is grounded, and the other end is connected to the +24V power supply.

[0056] The third pin of the isolation power chip U16 is grounded, and the fourth pin is connected to the +5V power supply, thereby providing an isolated +5V power supply to the high-voltage side circuit; one end of the second capacitor C66 is grounded, and the other end is connected to the output terminal of the isolation power chip U16.

[0057] Specifically, this embodiment achieves isolated energy transfer through the isolation power supply chip U16. The isolation power supply chip U16 converts the input-side DC24V power supply to the output-side DC power supply, and completely isolates the input-side DC24V power supply from the output-side DC5V power supply. This ensures that the DC24V power supply is unaffected by AC fluctuations, and that high-voltage short circuits or other faults on the 5V side will not damage the preceding circuitry or cause high-voltage leakage. Simultaneously, the output-side ground and the input-side ground are not at the same reference point, allowing them to withstand very high voltages without breakdown. This also provides a stable, clean, floating 5V operating power supply for the first operational amplifier U17.

[0058] Specifically, the isolation power supply chip U16 and the first operational amplifier U17 together form a complete isolation barrier. A barrier with an insulation strength of several kilovolts is established between the high-voltage side (dangerous side) and the low-voltage side (safe side), providing fundamental safety assurance. Power equipment on the high-voltage side (such as motors and frequency converters) generates significant common-mode noise, causing drastic fluctuations in its ground potential. If the measurement circuit shares a common ground with this, this fluctuating noise will be directly superimposed on the measurement signal. In this circuit, the input of the first operational amplifier U17 is referenced to the plane ground of the high-voltage side, while its output is referenced to the ground of the low-voltage side. The isolation barrier cuts off the direct electrical connection between these two grounds, thereby completely eliminating ground loop current and common-mode noise interference caused by the ground potential difference. The analog signal ultimately sent to the microcontroller unit (MCU) is referenced to analog ground, thus ensuring stable data acquisition.

[0059] Specifically, the first capacitor C64 is directly connected between the fourth pin of the isolation power supply chip U16 and ground, serving as an output decoupling capacitor to filter out high-frequency noise on the output power supply and provide a locally stable operating voltage for the first operational amplifier U17.

[0060] In a specific embodiment, the isolation amplification and signal conversion module includes a first operational amplifier U17, a fifth resistor R65, a sixth resistor R66, a seventh resistor R68, a third capacitor C67, and a fourth capacitor C68.

[0061] The two power input terminals of the first operational amplifier U17 are connected to +5V and +3.3V power supplies, respectively;

[0062] The non-inverting input and inverting input of the first operational amplifier U17 are respectively connected to the two ends of the sixth resistor R66, and the sixth resistor R66 is connected to the clamping diode D13;

[0063] The output of the first operational amplifier U17 is connected to the buffer and filter output module;

[0064] One end of the fifth resistor R65 is connected to a +5V power supply, and the other end is connected to one end of the seventh resistor R68. The other end of the seventh resistor R68 is grounded.

[0065] One end of the third capacitor C67 is connected to the +5V power supply, and the other end is grounded.

[0066] One end of the fourth capacitor C68 is connected to the sixth resistor R66, and the other end is grounded.

[0067] Specifically, the first operational amplifier U17 amplifies and conditions the small signal after voltage division from the high voltage, converting it into a low-voltage DC signal. Simultaneously, the first operational amplifier U17 acts as a second isolation barrier in the circuit. Internally, it uses magnetic or optical coupling technology to transmit the signal from the input to the output while maintaining electrical isolation between the input and output. Even if the input ground wire carries a high voltage, it will not be conducted to the output, ensuring the safety of the downstream processing circuitry. Ultimately, it outputs a clean, low-impedance DC low-voltage small signal that is linearly proportional to the input high-voltage signal.

[0068] Specifically, the input of the first operational amplifier U17 is the voltage across the sixth resistor R66. Since the sixth resistor R66 is a sampling resistor, the small signal voltage across the sixth resistor R66 is the signal sent to the first operational amplifier U17 for measurement.

[0069] Specifically, at the intersection of the fifth resistor R65, the sixth resistor R66, and the seventh resistor R68, following Kirchhoff's current law, the algebraic sum of the currents flowing into or out of the node is zero. Thus, the voltage at the node can be calculated, and the voltage across the sixth resistor R66 can be determined. This is the basis for the accuracy of the entire signal acquisition.

[0070] In a specific embodiment, the buffer and filter output module includes a second operational amplifier U18, an eighth resistor R10, a fifth capacitor C4, a sixth capacitor C5, and a seventh capacitor C65;

[0071] The non-inverting input of the second operational amplifier U18 is connected to the output of the first operational amplifier U17, and the inverting input is connected to its own output. One end of the eighth resistor R10 is connected to the output of the second operational amplifier U18, and the other end is connected to the sixth capacitor C5. The power supply of the second operational amplifier U18 is connected to a +3.3V power supply.

[0072] One end of the fifth capacitor C4 is connected to a +3.3V power supply, and the other end is grounded;

[0073] The other end of the sixth capacitor C5 is grounded;

[0074] One end of the seventh capacitor C65 is connected to a +3.3V power supply, and the other end is grounded;

[0075] One end of the eighth resistor R10 is connected to the output signal terminal Out.

[0076] Specifically, the non-inverting input of the second operational amplifier U18 receives the low-voltage analog signal output from the first operational amplifier U17. The output of the second operational amplifier U18 is connected to its inverting input via the eighth resistor R10, and the sixth capacitor C5 is connected between the final output and ground for output filtering. The final stable analog voltage signal output by the second operational amplifier U18 is directly sent to the output terminal Out. The second operational amplifier U18 significantly enhances its driving capability without changing the signal voltage magnitude and achieves isolation or buffering between the preceding and following stages. Due to its extremely high input impedance, the second operational amplifier U18 draws very little current from the signal source, thus obtaining almost the complete signal voltage. Simultaneously, due to its extremely low output impedance, it can provide a stable voltage to the subsequent load, unaffected by load variations.

[0077] Specifically, the sixth capacitor C5 and the eighth resistor R10 form a low-pass filter to further ensure the stability of the output signal.

[0078] Specifically, in this embodiment, the capacitors provided at the power supply pins of the isolation power chip U16 and the first operational amplifier U17 can filter out high-frequency noise on the power lines, provide the chip with a locally stable, low-impedance power supply, and prevent the chip from operating unstablely or oscillating.

[0079] In a specific embodiment, this embodiment also includes a high-impedance common reference measurement front-end network connected to the input attenuation and clamping module. It is used to establish a unified and stable reference benchmark for multiple AC signals without interfering with the original circuit, so as to realize multi-point synchronous, low-intrusion, and high-precision signal acquisition and correlation.

[0080] The high-impedance common-reference measurement front-end network includes a ninth resistor R71, a tenth resistor R72, and an eleventh resistor R73;

[0081] One end of the ninth resistor R71 is connected to the high-voltage AC input signal terminal, and its other end is connected to one end of the tenth resistor R72. The other end of the tenth resistor R72 is connected to one end of the eleventh resistor R73, and the other end of the eleventh resistor R73 is grounded. Figure 1 As shown, the other end of the eleventh resistor R73 is connected to GND.

[0082] Specifically, the three large-value resistors, the ninth resistor R71, the tenth resistor R72, and the eleventh resistor R73, are connected to the same reference plane in AC measurements of multiple identical circuits, which enables the correlation of multi-point measurements and accurate signal transmission, while minimizing the impact on the original circuit.

[0083] Specifically, this embodiment can be considered a fully functional module. On the high-voltage side, the AC signal to be tested is connected; on the low-voltage side, a 24V power supply is connected to the input terminal of the module, and the output terminal outputs an analog signal to the processing unit. Components on the high and low voltage sides can be wired separately and laid out in separate zones, avoiding complex crossover and mutual interference problems between high and low voltage, AC and DC signals. This greatly simplifies the design of the printed circuit board (PCB) and the difficulty of system integration, making the layout of the PCB and the system structure design more flexible and modular.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. An isolated AC high-voltage signal acquisition circuit with anti-common-mode interference, characterized in that, include: Isolated power supply module, input attenuation and clamping module, isolated amplification and signal conversion module, and buffer and filter output module; The output of the isolated power supply module is connected to the power input of the input attenuation and clamping module and the isolation amplification and signal conversion module, respectively. It is used to establish an independent working power reference that can electrically isolate the low-voltage side circuit from the high-voltage side circuit. The input attenuation and clamping module is connected to the isolation amplification and signal conversion module, and it can obtain its own power supply from the isolation power supply module. At the same time, it attenuates the input high-voltage AC signal and limits the amplitude of the attenuated AC signal to a preset safe voltage range. The isolation amplification and signal conversion module is used to isolate the attenuated AC signal on the high-voltage side and transmit it to the low-voltage side, thereby outputting a low-voltage analog signal with the low-voltage side ground as the reference potential. The buffer and filter output module is connected to the isolation amplification and signal conversion module. It is used to buffer and filter the low-voltage analog signal to enhance its driving capability and suppress noise, thereby outputting a stable analog voltage signal as the acquisition signal.

2. The isolated AC high-voltage signal acquisition circuit for resisting common-mode interference according to claim 1, characterized in that, The input attenuation and clamping module includes a first resistor, a second resistor, a third resistor, and a clamping diode; One end of the first resistor is connected to the high-voltage AC input signal terminal, and the other end is connected to one end of the second resistor. The other end of the second resistor is connected to one end of the third resistor, and the other end of the third resistor is connected to the isolation amplification and signal conversion module. The two ends of the clamping diode are connected to the +5V power supply and the isolation amplifier and signal conversion module, respectively.

3. The isolated AC high-voltage signal acquisition circuit for resisting common-mode interference according to claim 2, characterized in that, The isolated power supply module includes an isolated power chip, a first capacitor, and a second capacitor. The first pin of the isolation power chip is grounded, and the second pin is connected to a +24V power supply. One end of the first capacitor is grounded, and the other end is connected to a +24V power supply; The third pin of the isolation power chip is grounded, and the fourth pin is connected to the +5V power supply; one end of the second capacitor is grounded, and the other end is connected to the output terminal of the isolation power chip.

4. The isolated AC high-voltage signal acquisition circuit for resisting common-mode interference according to claim 3, characterized in that, The isolation amplification and signal conversion module includes a first operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor, and a fourth capacitor; The two power input terminals of the first operational amplifier are connected to a +5V and a +3.3V power supply, respectively; The non-inverting input and inverting input of the first operational amplifier are respectively connected to the two ends of the sixth resistor, and the sixth resistor is connected to the clamping diode; The output of the first operational amplifier is connected to the buffer and filter output module; One end of the fifth resistor is connected to a +5V power supply, and the other end is connected to one end of the seventh resistor, with the other end of the seventh resistor grounded. One end of the third capacitor is connected to a +5V power supply, and the other end is grounded. One end of the fourth capacitor is connected to the sixth resistor, and the other end is grounded.

5. The isolated AC high-voltage signal acquisition circuit for resisting common-mode interference according to claim 4, characterized in that, The buffer and filter output module includes a second operational amplifier, an eighth resistor, a fifth capacitor, a sixth capacitor, and a seventh capacitor; The non-inverting input of the second operational amplifier is connected to the output of the first operational amplifier, and the inverting input is connected to its own output. One end of the eighth resistor is connected to the output terminal of the second operational amplifier, and the other end is connected to the sixth capacitor. The power supply terminal of the second operational amplifier is connected to a +3.3V power supply. One end of the fifth capacitor is connected to a +3.3V power supply, and the other end is grounded; The other end of the sixth capacitor is grounded; One end of the seventh capacitor is connected to a +3.3V power supply, and the other end is grounded; One end of the eighth resistor is connected to the output signal terminal.

6. The isolated AC high-voltage signal acquisition circuit for resisting common-mode interference according to claim 5, characterized in that, It also includes a high-impedance common-reference measurement front-end network connected to the input attenuation and clamping module, which is used to establish a reference for the high-voltage side AC signal; The high-impedance common-reference measurement front-end network includes a ninth resistor, a tenth resistor, and an eleventh resistor; One end of the ninth resistor is connected to the high-voltage AC input signal terminal, and its other end is connected to one end of the tenth resistor. The other end of the tenth resistor is connected to one end of the eleventh resistor, and the other end of the eleventh resistor is grounded.

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