Industrial monitoring slow-varying signal acquisition and processing circuit based on voltage-controlled silicon oscillator

Abstract

The utility model discloses an industrial monitoring slowly varying signal acquisition processing circuit based on pressure control silicon oscillator, including the front protection circuit, signal conditioning circuit, pressure control silicon oscillator circuit and data processing circuit that connect gradually, the original slowly varying signal of sensor input is accessed front protection circuit input, and the signal is input to signal conditioning circuit after passing through the front protection circuit and exports standard voltage signal after pre -treatment, then standard voltage signal is input to pressure control silicon oscillator circuit and carries out voltage and frequency's linear conversion, and linear conversion signal is input to data processing circuit and exports after processing. The utility model discloses adopting pressure control silicon oscillator to replace analog-digital converter, on one hand, has completed the high accuracy collection of voltage signal and current signal, on the other hand, has also greatly simplified hardware circuit design, has reduced the overall power consumption of data acquisition, has reduced the processing pressure of processor, has improved monitoring system reliability, has reduced monitoring system operation and maintenance cost and difficulty.

Description

Technical Field

[0001] This utility model belongs to the technical fields of slowly varying signal acquisition, analog electronics, voltage-controlled silicon oscillators, and industrial monitoring, and specifically relates to an industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator. Background Technology

[0002] Industrial monitoring, as the nerve center of industrial production, is crucial for the precise control and dynamic management of the entire production process. By tracking key information such as equipment operating parameters, process indicators, energy consumption data, and environmental impact in real time, it can provide timely warnings of equipment malfunctions and safety hazards, strengthening production safety and preventing casualties and property losses. Furthermore, by analyzing data, it can optimize production processes, stabilize product quality, reduce defect rates, and enhance the core competitiveness of enterprises. At the same time, detailed monitoring of energy and material consumption can promote efficient resource utilization, reduce production costs, and facilitate green and low-carbon transformation. It also provides data support for environmental compliance, achieving a synergistic balance between economic and environmental benefits, making it an indispensable technological cornerstone for the high-quality development of modern industry.

[0003] Slow-moving variables in industrial monitoring, such as current, temperature, humidity, and pressure signals, while not as drastically impacting systems as sudden fault signals, harbor progressive risks. These signals (such as the accumulation of minor wear after long-term equipment operation, the slow increase in pipeline corrosion rates, gradual shifts in temperature and humidity in the production environment, and subtle decreases in material purity) exhibit small fluctuations and long durations, easily masked by short-term monitoring data. However, their long-term cumulative effects can lead to equipment performance degradation, decreased product quality stability, and hidden increases in energy consumption. Capturing and analyzing slow-moving variables helps companies anticipate potential trends, take intervention measures at the nascent stage of faults, and prevent small problems from escalating into major failures. Furthermore, it provides long-term data support for optimizing equipment maintenance cycles, fine-tuning process parameters, and upgrading resource allocation strategies, making it a crucial link in achieving refined management and sustainable operation in industrial production.

[0004] In industrial monitoring, the acquisition of slowly varying signals typically involves first conditioning the slowly varying signals output from the front-end sensors, then digitizing them via an analog-to-digital converter (ADC) before they enter the system for monitoring. The signal conditioning process uses active devices such as operational amplifiers and low-pass filters to adapt the voltage of the slowly varying signals. The digitization process uses an ADC to convert analog signals into digital signals. The entire data acquisition process requires a certain number of circuit components and is complex. When there are many slowly varying signals in industrial monitoring (64 or 128 channels) or the back-end processing chip does not have enough drive signal pins to acquire slowly varying signals, two situations arise: the first is to reduce the requirements and decrease the number of channels, and the second is to increase the back-end processor capabilities by selecting a processor with more drive pins. This inevitably leads to increased costs, and neither the first nor the second solution is the optimal solution. Utility Model Content

[0005] The technical problem solved by this utility model is to provide an industrial monitoring slowly changing signal acquisition and processing circuit based on a voltage-controlled silicon oscillator (VCO) that replaces the analog-to-digital converter, thereby significantly reducing the number and complexity of signal links.

[0006] Technical solution: To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0007] An industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator (VCO) includes a pre-protection circuit, a signal conditioning circuit, a VCO circuit, and a data processing circuit connected in sequence. The original slowly varying signal input from the sensor is connected to the input terminal of the pre-protection circuit. After passing through the pre-protection circuit, the signal is input to the signal conditioning circuit for pre-processing and output as a standard voltage signal. Then, the standard voltage signal is input to the VCO circuit for linear conversion between voltage and frequency. The linearly converted signal is input to the data processing circuit for processing and output.

[0008] Furthermore, the pre-protection circuit includes a common-mode filter capacitor, a first-stage surge protection circuit, a second-stage surge protection circuit, and a precision common-mode and differential-mode filter circuit.

[0009] Furthermore, the signal conditioning circuit includes a signal switching circuit, a follower circuit, and a low-pass filter to realize the current-to-voltage conversion and linearization compensation of the signal, converting it into a standard voltage signal that the data acquisition unit can directly process.

[0010] Furthermore, the signal switching circuit includes a relay U7, resistors R18 and R19, and a transistor Q3. Pins 2 and 4 of the relay U7 are connected to the back end of the pre-protection circuit, pin 7 is connected to analog ground through resistor R18, pin 5 is connected to analog ground through resistor R19, and pins 3 and 6 are connected to the front end of the follower circuit.

[0011] Furthermore, the follower circuit includes resistors R17 and R14, capacitor C19, and operational amplifier U6. Capacitors C20 and C22 filter the negative power supply of operational amplifier U6A, and capacitors C29 and C27 filter the positive power supply of operational amplifier U6. The low-pass filter includes resistors R15 and R16, capacitors C26 and C21, and operational amplifier U6B, which allows low-frequency signals to pass through while attenuating high-frequency signals.

[0012] Furthermore, the voltage-controlled silicon oscillator circuit uses the LTC6990IS6#TRMPBF chip.

[0013] Furthermore, the DIV pin of the LTC6990IS6#TRMPBF chip is connected to two series voltage divider resistors: resistor R171 and resistor R172.

[0014] Furthermore, the output voltage of the low-pass filter is connected to the SET pin of the LTC6990IS6#TRMPBF chip through resistor R169, and the OUT pin is the frequency output of the LTC6990, which is connected to the FPGA processing circuit at the back end.

[0015] Furthermore, the data processing circuit includes an FPGA processor circuit and a 100Mbps Ethernet communication circuit, with the frequency output of the voltage-controlled silicon oscillator uniformly connected to the FPGA processor for data processing.

[0016] Furthermore, the 100Mbps network communication circuit uses a LAN8720AI-CP-TR physical layer chip to receive signals from the FPGA processor circuit and send the signals out.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0018] This invention relates to an industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator (VCO). By replacing the analog-to-digital converter with a VCO, it achieves high-precision acquisition of voltage and current signals while significantly simplifying hardware circuit design, reducing overall power consumption during data acquisition, and lessening the processor's processing load. This improves the reliability of the monitoring system, reduces its operation and maintenance costs and complexity, accelerates deployment and expansion, ensures data quality and decision-making effectiveness, and enhances the system's compatibility and integration.

[0019] This invention relates to an industrial monitoring slowly changing signal acquisition and processing circuit based on a voltage-controlled silicon oscillator (VCO). By using a VCO instead of an analog-to-digital converter, and implementing slowly changing measurement with a single I / O port, the number and complexity of signal links are significantly reduced. Attached Figure Description

[0020] Figure 1 This refers to the overall hardware framework of the system.

[0021] Figure 2 This is the pre-protection circuit for channel 1.

[0022] Figure 3 This is the signal conditioning circuit for channel 1.

[0023] Figure 4 This is a voltage-controlled silicon oscillator circuit.

[0024] Figure 5 This is the formula for the frequency output of a voltage-controlled oscillator.

[0025] Figure 6 This is a circuit diagram for data processing.

[0026] Figure 7 It is a 100Mbps network communication circuit. Detailed Implementation

[0027] The present invention will be further illustrated below with reference to specific embodiments. The embodiments are implemented based on the technical solution of the present invention. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0028] like Figure 1 The diagram shows the hardware framework of the industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator (VCO) of this invention. The circuit includes a pre-protection circuit, a signal conditioning circuit, a VCO oscillator circuit, and a data processing circuit connected in sequence. The pre-protection circuit protects against various sudden overvoltage and overcurrent surges, preventing damage to the sensor, signal conditioning circuit, and downstream data acquisition equipment due to instantaneous energy impacts. The signal conditioning circuit primarily performs signal conversion and data communication. The VCO oscillator circuit performs linear voltage-to-frequency conversion. The data processing circuit performs signal conversion and data communication.

[0029] The original slowly varying signal input from the sensor is connected to the input terminal of the pre-protection circuit. After passing through the pre-protection circuit, the signal is input to the signal conditioning circuit for preprocessing and output as a standard voltage signal. Then, the standard voltage signal is input to the voltage-controlled silicon oscillator circuit for linear conversion between voltage and frequency. The linearly converted signal is then input to the data processing circuit for processing and output.

[0030] This utility model is based on a distributed temperature and displacement monitoring project for 64 channels of electromechanical equipment in a large steel plant. The temperature signal is a voltage signal from 0V to 1V, and the displacement signal is a current signal from 4mA to 20mA. For example... Figure 1 As shown, the overall hardware framework of the system is mainly divided into four sub-parts: pre-protection, signal conditioning circuit, voltage-controlled silicon oscillator circuit, and data processing circuit.

[0031] like Figure 2 As shown, the pre-protection circuit includes a common-mode filter capacitor, a first-stage surge protection circuit, a second-stage surge protection circuit, and a precision common-mode and differential-mode filter circuit. Figure 2 This is the pre-protection circuit for channel 1. Channels 2 through 64 are the same as channel 1.

[0032] Capacitors C23 and C28: Capacitors C23 and C28 are common-mode filter capacitors with a capacitance of 100pF and a filtering frequency band of 100MHz. One end of capacitor C23 is connected to the positive signal of the sensor, and the other end is connected to the housing of the data acquisition terminal. One end of capacitor C28 is connected to the negative signal of the sensor, and the other end is connected to the housing of the data acquisition terminal. When common-mode interference signals of equal magnitude and phase appear on the sensor cable, the common-mode interference will flow back to the housing of the data acquisition terminal through capacitors C23 and C28 immediately, reducing the harm of common-mode interference to monitoring accuracy and system stability. Furthermore, in industrial monitoring applications, the housing of the data acquisition terminal is generally connected to the equipment ground.

[0033] The first-stage surge protection circuit includes varistor M5, varistor M6, and decoupling inductor L4. Varistors M5 and M6 connected in parallel have a current capacity of 1600A, capable of protecting against surges up to 3200V. The decoupling inductor L4 utilizes the principle that inductor current cannot change abruptly; it generates a high electromotive force the moment the surge current passes through, forcing varistor M5 and M6 to conduct faster.

[0034] The second-stage surge protection circuit includes varistor M7, varistor M8, decoupling inductor L5, and transient voltage suppressor diode D4. The parameters of varistor M7, varistor M8, and decoupling inductor L5 are the same as those of varistor M5, varistor M6, and decoupling inductor L4. The transient voltage suppressor diode D4 is an SMCJ14CA type, and its main function is to provide precise protection for downstream components, preventing excessive residual voltage from the varistor from damaging them.

[0035] Precision common-mode and differential-mode filter circuit: includes capacitor C24, common-mode inductor L6, and capacitor C25. Capacitors C24 and C25 have a capacitance of 1nF and a filtering frequency band of 10MHz. Capacitors C24 and C25 are connected in parallel across the two ends of common-mode inductor L6, one end connected to the positive sensor signal and the other to the negative sensor signal. When high-frequency differential-mode interference occurs on the sensor cable, the interference can flow back to the negative sensor signal through capacitors C24 and C25. The function of common-mode inductor L6 is the same as that of capacitors C23 and C28; when a common-mode interference signal of equal magnitude and phase appears on the sensor cable, common-mode inductor L6 will prevent the common-mode interference signal from passing through the signal link.

[0036] In the field of industrial monitoring, surge protection design of sensor interfaces is a safety barrier to ensure the reliable operation of the entire monitoring system. The function of the pre-protection circuit is to resist various sudden overvoltage and overcurrent surge impacts, prevent damage to sensors, signal conditioning circuits, and downstream data acquisition equipment due to instantaneous energy impacts, and maintain the integrity and accuracy of monitoring signals.

[0037] like Figure 3 As shown, the signal conditioning circuit mainly includes a signal switching circuit, a follower circuit, and a low-pass filter. Figure 3 The signal conditioning circuit for channel 1 is shown below; channels 2 through 64 are identical to channel 1. Because the specific requirement is compatibility with both voltage and current acquisition, the current signal needs to be pre-converted into a standard voltage signal. Therefore, a relay switching circuit is required to achieve this function. The low-pass filter acts as a "purifier" to ensure signal quality. Its core function is to selectively attenuate high-frequency signals and retain useful low-frequency signals, effectively suppressing high-frequency noise interference commonly found in industrial environments. This ensures that the raw signals output by the sensor (such as slow variables like temperature, pressure, and flow rate) can be accurately acquired and processed by the back-end circuitry.

[0038] Signal switching circuit: Includes relay U7, resistors R18 and R19, and transistor Q3. Pins 2 and 4 of relay U7 are connected to the back end of the pre-protection circuit. Pin 7 is connected to analog ground through a 240K resistor R18, and pin 5 is connected to analog ground through a 49.9 ohm resistor R19. Pins 3 and 6 are connected to the front end of the follower circuit. When the sensor signal is a voltage signal, CH1_SW3 is low, transistor Q3 is not conducting, and relay U7 is in its default initial state, with pins 2 and 3 conducting, and pins 1 and 6 conducting. When the sensor signal is a current signal, CH1_SW3 is high, transistor Q3 conducts, relay U7 switches to the energized state, with pins 4 and 3 conducting, and pins 5 and 6 conducting.

[0039] Follower circuit: Resistors R17 and R14, capacitor C19, and operational amplifier U6A form the basic follower circuit. Although the follower circuit does not amplify the signal, its "high input impedance, low output impedance" characteristics make it a "bridge" in the signal link. Its core functions are to stabilize signal transmission, isolate impedance effects, and protect the preceding and following circuits. Capacitors C20 and C22 filter the negative 12V power supply of operational amplifier U6, while capacitors C29 and C27 filter the positive 12V power supply of operational amplifier U6.

[0040] Low-pass filter: Resistors R15 and R16, capacitors C26 and C21, and operational amplifier U6B form an active second-order low-pass filter. Its core function is to allow low-frequency signals to pass through while attenuating high-frequency signals, and it has superior performance compared to passive filters.

[0041] Signal conditioning circuits play an indispensable and core role in data acquisition systems, their importance manifesting in several key aspects. They perform precise preprocessing of raw, slowly varying signals. For example, weak current, pressure, and temperature signals from sensors often contain noise; conditioning circuits, through low-pass filtering, effectively eliminate this interference, significantly improving the signal-to-noise ratio and providing a clean signal source for subsequent data acquisition. Different sensors output signals with significantly different ranges, some potentially in the millivolt or even microvolt range. The amplification or attenuation functions of the conditioning circuit precisely scale the signal to a suitable range, ensuring that subsequent conversions do not suffer from accuracy loss due to excessively small signals or saturation distortion due to excessively large signals. Some sensors output current or nonlinear signals; conditioning circuits perform current-to-voltage conversion and linearization compensation, converting these signals into standard voltage signals that the data acquisition system can directly process, ensuring the accuracy of signal conversion. Furthermore, conditioning circuits provide electrical isolation, preventing common-mode interference and grounding loops between the sensor and the acquisition system, protecting the acquisition equipment from damage caused by high voltage and high current, and improving the stability and reliability of the entire system.

[0042] like Figure 4 As shown, the voltage-controlled silicon oscillator (VCO) circuit: The main task of the VCO circuit is to achieve linear conversion between voltage and frequency, and it is also the core of the entire system. The VCO oscillator uses the LTC6990IS6#TRMPBF chip, which is a precision silicon oscillator.

[0043] The principle of a voltage-controlled oscillator (VCO) is mainly based on an internal master oscillator, a programmable frequency divider, and a voltage control mechanism, enabling fixed-frequency or voltage-controlled oscillation. The frequency of the internal master oscillator can be programmed using a single resistor, RSET. The master oscillator generates a reference frequency, which, together with the internal frequency divider NDIV, determines the final output frequency. NDIV is programmable to eight settings from 1 to 128. By changing its division ratio, the flexibility of frequency selection is further expanded, making the device's programmable frequency range from 488Hz to 2MHz. The LTC6990 is a voltage-controlled oscillator (VCO). Adding a second resistor to the SET input enables linear voltage control of the output frequency for frequency modulation. By appropriately selecting these two resistors, a narrow-body or wide-body VCO tuning range can be configured, and the user can adjust the oscillation frequency by changing the voltage applied to the SET terminal. The following are the pin definitions and connections of the voltage-controlled oscillator:

[0044] 1. V+ (Pin 5): Power supply voltage (2.25V to 5.5V). This power supply must be noise-free and ripple-free. The DVCC+3V3 power supply is bypassed directly to the ground pin using a C22 0.1μF capacitor.

[0045] 2. DIV (Pin 4): The chip contains an internal analog-to-digital converter (A / D converter) referenced to V+. It generates a 4-bit binary code (DIVCODE) by monitoring the voltage (VDIV) on the DIV pin. This 4-bit code directly determines the division ratio of the internal frequency divider, thus adjusting the output frequency (final output frequency = main oscillator frequency / division ratio corresponding to DIVCODE). VDIV is typically generated by a resistor divider between V+ and ground (i.e., through two series resistors, with the intermediate node connected to the DIV pin). To ensure the accuracy of the A / D conversion, a resistor with a 1% accuracy must be connected to avoid VDIV deviating from the target value due to resistor errors, which would cause an incorrect division ratio. In the design, the series voltage divider resistors are a 1000K resistor R171 and an 887K resistor R172, with Ndiv = 128.

[0046] 3. SET (Pin 3): The SET pin uses a fixed 1V voltage and an external resistor to form a stable current ISET, which is used to program the main oscillator frequency. It is the "core input port" for frequency control of the LTC6990. Figure 4 In this circuit, the output voltage of the low-pass filter is connected to the SET pin through a 100K resistor R169, allowing the LTC6990 to operate as a voltage-controlled oscillator in its simplest form. The final output frequency formula for FOUT is as follows: Figure 5 As shown. Substituting the parameters one by one into the formula, where Ndiv=128, Rvco=100K, Rset=100K, Vset=1V, the final formula for the voltage-controlled oscillator is: Vctrl is the output voltage of the low-pass filter, ranging from 0V to 1V.

[0047] 4. GND (Pin2): The ground pin of LTC6990, directly grounded.

[0048] 5. OUT (Pin6): Frequency output of LTC6990, connected to the back-end FPGA processor.

[0049] This invention simplifies the signal link by abandoning the traditional digital-to-analog converter (DAC). The DAC works by converting voltage into digital code in real time before it enters the back-end processing chip. Without a DAC, the voltage signal must enter the back-end processing chip in a different linear form. This is where the role of the voltage-controlled silicon controlled oscillator (VCO) in gradually changing voltage conversion becomes apparent. The VCO (typically referring to an oscillator composed of a thyristor-controlled silicon controlled oscillator) in electronic circuits primarily functions to efficiently convert DC power into AC signals of a specific frequency. Its core value lies in utilizing the unidirectional conductivity and trigger control characteristics of the thyristor to flexibly control the frequency, amplitude, or duty cycle of the output AC signal. Specifically, this type of oscillator uses the thyristor's trigger-activated on / off state switching, combined with energy storage elements such as inductors and capacitors, to form an oscillation circuit: when the thyristor is triggered and turned on, the DC power supply releases energy to the energy storage element; when the thyristor is turned off, the energy storage element discharges through a reverse circuit, forming periodic current or voltage oscillations, thereby outputting an AC waveform. Its unique advantages lie in the strong current carrying capacity and high temperature resistance of the silicon controlled rectifier (SCR), enabling it to operate stably in high-power scenarios (such as industrial heating, motor speed control, and high-frequency induction equipment). Furthermore, by adjusting the phase or frequency of the trigger signal, the frequency or power of the output AC signal can be directly changed to meet the energy requirements of different loads. This technical solution uses a voltage-controlled silicon oscillator to achieve linear voltage-frequency conversion. The core is to precisely design the control circuit to ensure a strictly proportional relationship between the change in the input control voltage (Vin) and the frequency (fout) of the output AC signal. The back-end processing chip then calculates the frequency in a time-division multiplexing manner (at 1-second or 2-second intervals), ultimately enabling a single I / O port to complete the function of acquiring slowly changing signals.

[0050] like Figure 6 and 7 As shown, the data processing circuit includes an FPGA processor circuit and a 100Mbps network communication circuit. Figure 6 As shown, the back-end FPGA processor uses an XC7A35T-2CSG324I FPGA. All 64 frequency outputs are uniformly connected to BANK14 and BANK15 of U3 for calculation. Utilizing the parallel processing capability of the FPGA, all 64 frequencies can be calculated simultaneously.

[0051] 100Mbps network communication circuit: such as Figure 7As shown, the 100Mbps Ethernet communication circuit is designed using the LAN8720AI-CP-TR physical layer chip. The LAN8720AI-CP-TR and the FPGA use an RMII interface. Compared to the MII interface, the RMII interface reduces the number of pins, saving PCB space and reducing costs, making it suitable for applications such as embedded systems with strict size requirements. It transmits Ethernet data using fewer signal lines, typically including transmit data signals, receive data signals, clock signals, and control signals, and can connect to processors or FPGAs that support the RMII interface. RMII interface signal definitions:

[0052] PC4 / RMII_RXD0, PC5 / RMII_RXD1: Receive data signal lines used to receive data from the Ethernet link. They function as receive signal lines after the PHY chip has booted up, and can also function as MODE signal lines during PHY startup.

[0053] PG13 / RMII_TXD0, PG14 / RMII_TXD1: Transmit data signal lines, used to output the data to be transmitted by the chip to the Ethernet link.

[0054] PG11 / RMII_TX_EN: Send enable signal line, but this signal line is generally not used in RMII interfaces.

[0055] PA7 / RMII_CRS_DV: Carrier Sense / Data Valid signal line, used to indicate whether data is currently being transmitted and whether a carrier signal is present.

[0056] PA1 / RMII_REF_CLK: Reference clock signal, typically 50MHz, provides the operating clock for the chip.

[0057] PA2 / ETH_MDIO: Media Independent Interface Data Signal Line, used for communication with external devices. It is mainly used to access the registers of the PHY chip to implement configuration and status reading functions.

[0058] PC1 / ETH_MDC: Media Independent Interface Clock Signal Line, providing clock for MDIO and working with MDIO to access PHY chip registers.

[0059] PB0 / ETH_RESET: Ethernet link reset signal line, used to perform a global reset of the Ethernet link.

[0060] The data processing circuit mainly performs two functions: signal conversion and data communication. Signal conversion is to convert the pulse signal output by the voltage-controlled silicon oscillator circuit into analog quantities output by the sensor, such as temperature in degrees Celsius, pressure in Newtons, and current in milliamperes. The data communication function is to send the converted analog quantities to the industrial monitoring terminal through the 100 Mbps Ethernet port, so that the industrial monitoring terminal can monitor and control them in a unified manner.

[0061] This invention is designed based on the actual needs of large-scale steel plant electromechanical equipment monitoring systems. Due to the large number of sensors in practical applications, conventional data acquisition frameworks significantly increase the complexity of the monitoring system. This invention reduces the complexity of data acquisition by employing redundancy removal, standardization, and lightweight design, making data acquisition more adaptable to the harsh physical environment, dense equipment layout, and high-efficiency production demands of steel plants. Ultimately, it achieves the monitoring goals of stable operation, low-cost maintenance, and efficient decision-making, providing fundamental support for continuous production and equipment reliability in steel plants.

[0062] This invention uses a voltage-controlled silicon oscillator (VCO) to replace the analog-to-digital converter (ADC), achieving high-precision acquisition of voltage and current signals while significantly simplifying hardware circuit design, reducing overall power consumption during data acquisition, and decreasing processor load. To date, over 100 devices (with a total of over 6000 acquisition channels) have been successfully operating for more than six months, improving the reliability of the monitoring system, reducing its operation and maintenance costs and complexity, accelerating deployment and expansion, ensuring data quality and decision-making effectiveness, and enhancing its compatibility and integration.

[0063] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. An industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator, characterized in that: It includes a pre-protection circuit, a signal conditioning circuit, a voltage-controlled silicon oscillator circuit, and a data processing circuit connected in sequence. The original slowly changing signal input from the sensor is connected to the input terminal of the pre-protection circuit. After passing through the pre-protection circuit, the signal is input to the signal conditioning circuit for pre-processing and output as a standard voltage signal. Then, the standard voltage signal is input to the voltage-controlled silicon oscillator circuit for linear conversion between voltage and frequency. The linearly converted signal is input to the data processing circuit for processing and output.

2. The industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator according to claim 1, characterized in that: The pre-protection circuit includes a common-mode filter capacitor, a first-stage surge protection circuit, a second-stage surge protection circuit, and a precision common-mode and differential-mode filter circuit.

3. The industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator according to claim 1, characterized in that: The signal conditioning circuit includes a signal switching circuit, a follower circuit, and a low-pass filter, which realizes the current-to-voltage conversion and linearization compensation of the signal, converting it into a standard voltage signal that the data acquisition unit can directly process.

4. The industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator according to claim 3, characterized in that: The signal switching circuit includes relay U7, resistor R18, resistor R19 and transistor Q3. Pins 2 and 4 of relay U7 are connected to the back end of the pre-protection circuit, pin 7 is connected to analog ground through resistor R18, pin 5 is connected to analog ground through resistor R19, and pins 3 and 6 are connected to the front end of the follower circuit.

5. The industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator according to claim 3, characterized in that: The follower circuit includes resistors R17 and R14, capacitor C19, and operational amplifier U6. Capacitors C20 and C22 filter the negative power supply of operational amplifier U6A, while capacitors C29 and C27 filter the positive power supply of operational amplifier U6. The low-pass filter includes resistors R15 and R16, capacitors C26 and C21, and operational amplifier U6B, which allows low-frequency signals to pass through while attenuating high-frequency signals.

6. The industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator according to claim 1, characterized in that: The voltage-controlled silicon oscillator circuit uses the LTC6990IS6#TRMPBF chip.

7. The industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator according to claim 6, characterized in that: The DIV pin of the LTC6990IS6#TRMPBF chip is connected to two series voltage divider resistors: resistor R171 and resistor R172.

8. The industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator according to claim 6, characterized in that: The output voltage of the low-pass filter is connected to the SET pin of the LTC6990IS6#TRMPBF chip through resistor R169. The OUT pin is the frequency output of the LTC6990, which is connected to the FPGA processing circuit at the back end.

9. The industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator according to claim 1, characterized in that: The data processing circuit includes an FPGA processor circuit and a 100Mbps network communication circuit. The frequency output of the voltage-controlled silicon oscillator is uniformly connected to the FPGA processor for data processing.

10. The industrial monitoring slowly varying signal acquisition and processing circuit based on a voltage-controlled silicon oscillator according to claim 9, characterized in that: The 100Mbps network communication circuit uses the LAN8720AI-CP-TR physical layer chip to receive signals from the FPGA processor circuit and send the signals out.

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