High precision feedback control circuit for industrial monitoring environments

Abstract

The utility model discloses a kind of high-precision feedback control circuit for industrial monitoring environment, including analog signal acquisition circuit, digital processing circuit and analog control output circuit;Analog signal acquisition circuit includes preamplifier protection circuit, sensor interface circuit, signal conditioning circuit and analog-digital conversion circuit;The collection of sensor analog signal, signal conditioning and analog-digital conversion are realized;Digital processing circuit connects the analog-digital conversion circuit of front end and the digital-analog conversion circuit of rear end, realizes the digital processing of signal, and the control of the analog-digital conversion circuit of front end and the digital-analog converter of rear end;Analog control output circuit includes digital-analog converter and gigabit ethernet communication circuit, converts the digital control quantity output by digital processing circuit into continuous adjustable analog signal, drives actuator to realize accurate adjustment to controlled object, guarantees the security and accuracy of measurement feedback system.

Description

Technical Field

[0001] This utility model belongs to the fields of data acquisition technology, digital-to-analog conversion technology, analog electronics technology, and industrial monitoring feedback control technology, specifically relating to a high-precision feedback control circuit for industrial monitoring environments. Background Technology

[0002] In the field of industrial monitoring, feedback control is a core technology for ensuring system stability, accuracy, and reliability. ADCs (Analog-to-Digital Converters) and DACs (Digital-to-Analog Converters) are crucial bridges connecting the analog physical world and the digital control system. The ADC converts analog signals acquired by sensors into digital signals for the controller to process, while the DAC converts the digital control signals output by the controller back into analog signals to drive actuators. Together, they form a complete feedback loop.

[0003] The basic logic of an industrial feedback control system is as follows:

[0004] Controlled object → Sensor (analog signal) → ADC (digital signal) → Controller (calculates deviation) → DAC (analog signal) → Actuator → Controlled object.

[0005] (1) The role of ADC: to convert the analog signals (voltage, current, etc.) output by sensors (such as temperature, pressure, flow sensors) into digital signals for the controller (such as PLC, MCU, DCS) to analyze and process (such as comparing with the set value and calculating the deviation).

[0006] (2) The function of DAC: to convert the digital control commands (such as the deviation compensation after PID adjustment) output by the controller into analog signals (such as 0-10V voltage and 4-20mA current) to drive actuators (such as valves, heaters and motors) to adjust the state of the controlled object.

[0007] (3) The core of feedback: The ADC collects the feedback signal of the controlled object in real time, and the controller dynamically adjusts the DAC output according to the deviation, so that the controlled object is stabilized at the set value and the influence of external interference (such as load fluctuations and environmental changes) is eliminated.

[0008] Temperature feedback control in industrial monitoring:

[0009] (1) The temperature control accuracy of high-temperature furnaces and chemical reactors directly affects product quality (such as material sintering and chemical synthesis), and stable control needs to be achieved through a feedback system. In temperature feedback control, thermocouples / resistance devices (temperature sensors) collect the furnace temperature → output analog signals (such as thermocouples outputting mV-level voltage, and resistance devices outputting resistance changes which are converted into 4-20mA current by a transmitter) → ADC converts the analog signals into digital temperature values ​​→ controller (such as PLC) compares the set temperature and uses a PID algorithm to calculate the deviation compensation amount → DAC outputs analog signals (such as 0-10V) → drives the power regulation module (such as a thyristor power regulator) of the heater (actuator) → after the furnace temperature changes, it is collected by the sensor again, forming feedback.

[0010] (2) The pressure of industrial pipelines (such as oil and gas pipelines) or hydraulic equipment must be kept stable within the set range to avoid overpressure leakage or insufficient pressure affecting production. In pressure feedback control, the pressure sensor (such as strain gauge type) collects the pipeline pressure → outputs an analog signal (such as 4-20mA corresponding to 0-10MPa) → ADC converts it into a digital pressure value → the controller (such as DCS system) calculates the deviation from the set pressure → DAC outputs an analog signal (such as 4-20mA) → drives the electric regulating valve (actuator) to adjust the opening degree (the larger the opening degree, the faster the pipeline pressure is released) → the pipeline pressure change is collected by the sensor again to form feedback.

[0011] (3) The speed / position control of industrial motors (such as servo motors and stepper motors) directly affects the accuracy of the production line (such as conveyor belt speed synchronization and machine tool machining dimensions). In motor feedback control, encoders / Hall sensors collect motor speed / position data (outputting analog or pulse signals, which need to be conditioned into analog quantities).

[0012] →ADC converts to digital signal →Controller (e.g., servo driver) compares with set speed / position and calculates deviation →DAC outputs analog current signal (e.g., 0-5A) →Drives motor windings (actuator) to adjust speed / torque →Motor state changes are collected again by sensor to form feedback.

[0013] (4) Vibrations in industrial machine tools (lathes, milling machines) and high-speed motors can lead to decreased machining accuracy (e.g., excessive surface roughness of parts) and increased equipment wear (e.g., shortened bearing life). Feedback control is needed to suppress vibration. A piezoelectric accelerometer (attached to the machine tool spindle or motor housing) collects vibration signals → outputs a mV-level analog voltage (proportional to acceleration) → an ADC (e.g., a 24-bit high-precision ADC) converts the signal into a digital signal (sampling rate must be ≥ twice the vibration frequency; e.g., 10kHz sampling for vibrations within 5kHz) → a controller (e.g., FPGA, low-latency processing) analyzes the vibration frequency (e.g., the first and second harmonic resonance of spindle rotation) → calculates the amplitude and phase of the reverse vibration → a DAC outputs an analog voltage (e.g., 0-5V) → drives a piezoelectric actuator (attached to the machine tool base) to generate reverse mechanical vibration → cancels spindle vibration → the ADC collects the vibration signal again, forming feedback.

[0014] In summary, in the field of industrial monitoring, ADCs and DACs, through feedback collaboration of "analog signal acquisition → digital processing → analog control output," achieve high-precision and high-stability control of key parameters such as temperature, pressure, motors, and vibration. This determines the reliability of industrial systems and is a core component of modern industrial automation. Currently, most industrial monitoring circuits do not specifically design feedback systems, only performing data acquisition, data processing, data analysis, and data monitoring. When data problems occur, manual intervention in equipment operation is often required. Circuits with integrated feedback control often suffer from unstable control and low control signal accuracy. This invention specifically proposes a high-precision feedback control circuit for the industrial monitoring field to improve the above problems. Utility Model Content

[0015] The technical problem solved by this utility model is to provide a high-precision feedback control circuit for industrial monitoring environments, which enables high-precision and high-stability control of key parameters such as temperature, pressure, motor, and vibration.

[0016] Technical solution: To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0017] A high-precision feedback control circuit for industrial monitoring environments includes an analog signal acquisition circuit, a digital processing circuit, and an analog control output circuit.

[0018] The analog signal acquisition circuit includes a pre-protection circuit, a sensor interface circuit, a signal conditioning circuit, and an analog-to-digital conversion circuit; it realizes the acquisition, signal conditioning, and analog-to-digital conversion of the sensor's analog signals.

[0019] The digital processing circuit connects the front-end analog-to-digital converter circuit and the back-end digital-to-analog converter circuit, including the ZYNQ core board, to realize the digital processing of signals and the control of the front-end analog-to-digital converter circuit and the back-end digital-to-analog converter.

[0020] The analog control output circuit includes a digital-to-analog converter and a gigabit Ethernet communication circuit, which converts the digital control quantity output by the digital processing circuit into a continuously adjustable analog signal to drive the actuator to achieve precise adjustment of the controlled object.

[0021] Furthermore, the pre-protection circuit includes a first-stage surge protection circuit, a second-stage surge protection circuit, and a common-mode and differential-mode suppression circuit connected in sequence.

[0022] Furthermore, the sensor interface circuit is implemented through a relay switching circuit, connecting sensors with different input types and converting them into a uniformly conditioned voltage signal.

[0023] Furthermore, the signal conditioning circuit includes a follower circuit and a second-order analog filter to amplify, filter, isolate, and nonlinearly correct the voltage signal output by the sensor interface circuit.

[0024] Furthermore, the analog-to-digital conversion circuit uses the AD7768BSTZ chip and peripheral circuits to convert the conditioned analog signal output by the signal conditioning circuit into a digital signal.

[0025] Furthermore, the ZYNQ core board includes a PS processing system circuit and a PL core interface circuit, which are connected to the front-end analog-to-digital conversion circuit, the back-end digital-to-analog conversion circuit, and the actuator.

[0026] Furthermore, the analog-to-digital converter circuit of the analog control output circuit is connected to the digital processing circuit, and also to a detection device. The digital control quantity output by the digital processing circuit drives the actuator for precise adjustment. Beneficial effects: Compared with the prior art, this utility model has the following advantages:

[0027] This invention relates to a high-precision feedback control circuit for industrial environmental monitoring. It constructs a closed-loop system integrating high-precision pressure sensing, real-time signal processing, and intelligent feedback control. The system acquires gas or liquid pressure signals via a high-precision pressure sensor, amplifies and filters the signals through a low-noise signal conditioning module, performs analog-to-digital conversion via a high-speed ADC, and then performs data processing and error compensation through an embedded main control unit. Combined with a preset pressure threshold, dynamic feedback is achieved—when the measured pressure deviates from the set range, the system automatically drives the actuator (such as a regulating valve or pump) to adjust. Practical application and testing have shown that this significantly improves testing accuracy and ensures the safety and precision of the measurement feedback system. Attached Figure Description

[0028] Figure 1 This is a diagram of the overall hardware framework of this utility model.

[0029] Figure 2 This is the first-stage surge protection circuit of this utility model.

[0030] Figure 3 This invention relates to a second-stage surge protection circuit.

[0031] Figure 4 This invention relates to a common-mode and differential-mode filter circuit.

[0032] Figure 5 This invention relates to a relay switching circuit.

[0033] Figure 6 This is the follower circuit of this utility model.

[0034] Figure 7 This invention relates to a second-order low-pass filter circuit.

[0035] Figure 8 This utility model relates to a charge conversion circuit.

[0036] Figure 9 This invention relates to an analog-to-digital converter circuit.

[0037] Figure 10 This is a connection block diagram of the ZYNQ core board of this utility model.

[0038] Figure 11 This is a physical image of the ZYNQ core board of this utility model.

[0039] Figure 12 This utility model relates to a gigabit Ethernet communication circuit.

[0040] Figure 13 This invention relates to a digital-to-analog converter circuit.

[0041] Figure 14 This is a diagram showing the connection between the analog-to-digital converter, the digital-to-analog converter, and the gigabit network signal to the ZYNQ core board. Detailed Implementation

[0042] 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.

[0043] like Figure 1 As shown, the high-precision feedback control circuit for industrial monitoring environments of this utility model generally includes an analog signal acquisition circuit, a digital processing circuit, and an analog control output circuit.

[0044] The analog signal acquisition circuit includes a pre-protection circuit (first-stage surge protection circuit, second-stage surge protection circuit, and common-mode and differential-mode suppression circuit), a sensor interface circuit (relay switching circuit), a signal conditioning circuit (follower circuit, second-order analog filter), and an analog-to-digital conversion circuit. The digital processing circuit includes a power supply and basic power supply circuit, and the ZYNQ core board (including PS processing system circuit and PL core interface circuit). The analog control output circuit includes a digital-to-analog conversion circuit, a network transformer, and an RJ45 communication interface.

[0045] The monitoring equipment is equipped with various monitoring sensors, commonly including voltage-type temperature sensors, voltage-type pressure sensors, and vibration sensors. Sensor signals are connected to the circuit via shielded cables. For example... Figure 1 As shown, the circuit in this embodiment sequentially includes a monitoring device, an industrial sensor input, a first-stage surge protection circuit, a second-stage surge protection circuit, a common-mode and differential-mode suppression circuit, a relay switching circuit, a follower circuit, a second-order analog filter, an analog-to-digital converter, a ZYNQ core board, a digital-to-analog converter, and the monitoring device connected to it. The ZYNQ core board is also connected to a network transformer. Temperature, pressure, and vibration sensors are connected to the relay switching circuit.

[0046] The specific implementation process of this application is described below with reference to the specific circuit structure and principle:

[0047] Analog signal acquisition circuit: In the feedback control process, the core objective of the analog signal acquisition circuit is to convert the weak, noisy analog signal output by the sensor into a high-quality signal suitable for ADC conversion, so as to provide a reliable input for subsequent digital processing.

[0048] First-level surge protection circuit: such as Figure 2 The diagram shows the first-stage surge protection circuit of the feedback control circuit, including varistor M1, varistor M2, and decoupling inductor L1. Varistors M1 and M2 are both RL1812A390K models. The two varistors M1 and M2 are connected in parallel to protect against surge voltages up to 3200V. L1 is the decoupling inductor, which, in conjunction with the second-stage surge protection circuit, accelerates the conduction speed of M1 and M2. Capacitors C11 and C17 are common-mode filter capacitors, filtering out high-frequency common-mode interference on the sensor cable.

[0049] Second-stage surge protection circuit: such as Figure 3The diagram shows the second-stage surge protection circuit of the feedback control circuit, which includes varistor M3, varistor M4, decoupling inductor L2, and diode D1. Varistor M3 is model RL1812A390K, and varistor M4 is model RL1812A390K. The two varistors M3 and M4 are connected in parallel to protect against surge voltages of up to 3200V. L2 is a decoupling inductor, which, together with transient suppression diode D1, accelerates the conduction rate of M3 and M4.

[0050] Industrial monitoring environments involve the start-up and shutdown of numerous high-power operating devices. During these start-up and shutdown operations, high-energy surge voltages are generated, making surge protection circuits essential. By employing a redundant design of two-stage surge protection circuits, the high reliability of the feedback control circuit is significantly enhanced.

[0051] Common-mode and differential-mode rejection circuits: such as Figure 4 As shown, the common-mode and differential-mode filter circuit of the feedback control circuit includes capacitor C13, common-mode inductor L3 and capacitor C14. Among them, capacitors C13 and C14 are differential-mode capacitors, which filter out high-frequency differential-mode interference on the sensor signal, and common-mode inductor L3 blocks high-frequency common-mode interference on the sensor signal from passing through.

[0052] Sensor interface circuit: Sensor output signals come in various forms (voltage, current, vibration, etc.), and the sensor interface circuit needs to convert them into a uniform, conditionable voltage signal. For voltage-type sensors (such as the mV-level signals output by thermocouples), a... Figure 6 The voltage follower shown implements high input impedance (≥10MΩ) for buffering to avoid signal attenuation caused by load effects. A ceramic capacitor C5 in series at the front end filters out high-frequency glitches. For current-type sensors (4-20mA standard signal), a metal film resistor R19 with 100Ω ±0.1% accuracy and 10ppm / ℃ temperature drift is used. Figure 5 The current is converted to a voltage of 0.4-2V, and the operational amplifier, in conjunction with resistors and capacitors, forms a second-order low-pass filter circuit. Figure 7 Suppress electromagnetic interference. For charge-type sensors (such as piezoelectric accelerometers), use ultra-low bias current operational amplifiers to construct charge amplifiers (such as... Figure 8 As shown in the diagram, the feedback loop uses a polypropylene capacitor C124 to convert the pC-level charge signal into voltage, while a bleeder resistor R117 is added to prevent charge accumulation. The sensor interface circuit uses, as shown in the diagram... Figure 5 The relay switching circuit shown below has the following specific circuit structure:

[0053] The relay switching circuit includes U2, resistor R5, capacitor C6, capacitor C7, relay U4, relay U5, and relay U7. U2 (PSSI2010SAY) is a constant current source driver. Resistor R5, capacitor C6, and capacitor C7 form a constant current source power supply circuit. Resistor R5 is the output current configuration resistor, configured by the formula Iout = 0.617 / R5 + 15uA, so the constant current value is 4mA. IEPE+POWER supplies power to U2 after passing through capacitors C6 and C7. Capacitor C12 and resistor R18 form a first-order high-pass filter with a cutoff frequency of 1 / 2 / 3.14 / C12 / R18 = 0.1Hz. The relay switching circuit switching modes are as follows:

[0054] CH1_SW1 low, CH1_SW2 low, CH1_SW3 low: Relays U4 pins 2-3 are on, relays U5 pins 2-3 are on, relays U7 pins 2-3 are on, signal conditioning mode is vibration acquisition mode.

[0055] CH1_SW1 high, CH1_SW2 high, CH1_SW3 low: Relay U4 pins 5-6 are on, relay U5 pins 3-4 are on, relay U7 pins 2-3 are on, signal conditioning mode is pressure voltage acquisition mode, R18 is the circuit input resistance of 1.5M ohms.

[0056] CH1_SW1 high, CH1_SW2 high, CH1_SW3 high: Relay U4 pins 5-6 are on, relay U5 pins 3-4 are on, relay U7 pins 3-4 are on. The signal conditioning mode is temperature current mode. R19 is the circuit current sampling resistor with a current of 100 ohms. The 4-20mA current is converted into 400-2000mV after passing through the sampling resistor.

[0057] Signal conditioning circuits: such as Figure 6 and 7 As shown, the signal conditioning circuit mainly includes a follower circuit ( Figure 6 (U3A) and second-order low-pass filter ( Figure 7 The conditioning module (U3B) is the core component for improving signal quality, amplifying, filtering, isolating, and correcting nonlinearities in the voltage signal output from the sensor interface circuit. The voltage follower, while transmitting the signal, also provides impedance matching. The preceding signal source requires a "high-impedance load" (to avoid current loss), while the following load requires a "low-impedance drive source" (to ensure distortion-free signal transmission). The voltage follower is the ideal bridge between "high input impedance and low output impedance," achieving impedance matching between the preceding and following stages and improving signal transmission efficiency and quality. The low-pass filter suppresses high-frequency noise while preserving the effective signal.

[0058] Follower circuit: such as Figure 6As shown, the follower circuit includes resistors R8 and R4, capacitor C5, and operational amplifier U3A. AVCC-12V supplies power to the negative power supply of the operational amplifier through capacitors C8 and C10, and AVCC+12V supplies power to the positive power supply of the operational amplifier through capacitors C18 and C16.

[0059] Second-order analog filter (second-order low-pass filter circuit): such as Figure 7 As shown, the second-order low-pass filter circuit includes resistors R6 and R7, capacitors C15 and C9, and operational amplifier U3B, with a cutoff frequency of 100kHz (-3dB).

[0060] Analog-to-Digital Conversion Circuit: The analog-to-digital conversion circuit in analog signal acquisition is the core component that converts the conditioned analog signal into a digital signal. It utilizes a high-precision ADC chip to meet high accuracy requirements, and a stable reference voltage is provided by a precision reference source. A low-noise operational amplifier forms a buffer circuit at the front end to prevent load changes from affecting signal integrity. An RC low-pass filter is connected in series between the ADC and the pre-stage driver circuit to filter out super-Nyquist frequency noise. A multi-stage decoupling network consisting of a 10μF electrolytic capacitor and a 0.1μF ceramic capacitor is connected in parallel at the power supply to suppress power supply noise coupling. The digital interface uses a parallel bus to connect to the microprocessor.

[0061] like Figure 9 The diagram shows the circuit schematic of the analog-to-digital converter (ADC). The ADC mainly consists of the ADC U17 and peripheral circuitry. The ADC U17 uses the AD7768BSTZ chip. The AD7768 is a high-performance analog-to-digital converter (ADC) that uses Δ-Σ modulation technology to achieve high-precision data acquisition. Its working principle is as follows: The input signal first passes through an analog anti-aliasing filter to filter out components exceeding the Nyquist frequency, preventing aliasing. Then, the signal enters the Δ-Σ modulator, where, through internal differential and integral feedback loops, the analog signal is converted into a series of 1-bit data streams at a high sampling rate. This process improves signal linearity. Subsequently, the 1-bit data stream enters a digital filter, which typically uses an FIR or IIR structure to convert the oversampled data into a higher-bit digital signal conforming to the Nyquist sampling theorem, while reducing noise. Finally, the processed digital signal is output through the SPI interface for data exchange with an external processor. The AD7768 supports hardware FIFO buffering and software buffering, effectively managing high-speed data streams.

[0062] The input terminal of analog-to-digital converter U17 is connected to Figure 7 The output terminals of the second-order analog filter shown are AIN0+, AIN0- to AIN7+, AIN7-: these are the inputs of signals 1 to 8, respectively. The input terminals of the analog-to-digital converter U17 are connected to... Figure 10The ZYNQ core board shown has DOUT0-7 as the data output pins for channels 1-8 of the AD7768, respectively. DCLK: AD7768 conversion data clock output, DRDY: AD7768 data ready output.

[0063] exist Figure 9 In the diagram, U18 is the ADR444ARMZ. The ADR444ARMZ is an ultra-low noise, high-precision LDOXFET reference voltage source chip from Analog Devices (ADI). The system AVCC+5V is filtered by capacitors C114 and C115 and then connected to the VIN pin of the ADR444ARMZ. The VOUT pin of the ADR444ARMZ is filtered by capacitors C116 and C117 to form the system AVCC+4V reference voltage.

[0064] Digital processing circuitry: This includes the ZYNQ core board, power supply and basic power supply circuitry, and its peripheral circuitry. For example... Figure 10 The image shown is a schematic diagram of the ZYNQ core board. Figure 11 The image shows the physical diagram of the ZYNQ core board for the feedback control circuit, specifically including:

[0065] Marker 1: XC7Z020-2CLG400I processor, responsible for analog-to-digital conversion, feedback control algorithm calculation, digital-to-analog conversion, etc.

[0066] Mark 2: MT41K256M16TW-107IT:P model DDR3, two 512MB DDR3 chips together make up 1GB DDR3 memory.

[0067] Mark 3: SDINBDA4-128G model 128GB EMMC, used for offline storage of acquired industrial data.

[0068] Logo 4: RTL8211F-CG Gigabit Ethernet chip, responsible for data communication between the ZYNQ core board and the application layer.

[0069] Logo 5: The power conditioning circuit of the ZYNQ core board is responsible for providing a stable power system to the XC7Z020-2CLG400I processor.

[0070] Mark 6: FX8-100P-SV1(91)B2B inter-board connector, responsible for signal connection between ZYNQ core board and feedback circuit.

[0071] The ZYNQ core board features a heterogeneous architecture of "ARM Cortex-A9 processor (PS, processing system) + FPGA (PL, programmable logic)". Specifically:

[0072] In the feedback control process, the digital processing circuit solution based on the ZYNQ series (such as ZYNQ-7000) fully utilizes the advantages of its heterogeneous architecture of "ARM Cortex-A9 processor (PS, processing system) + FPGA (PL, programmable logic)" to achieve a balance between real-time performance and flexibility, and is especially suitable for high dynamic and high-precision industrial control scenarios (such as motor servo, vibration suppression, and multivariable process control).

[0073] Power Supply and Basic Power Supply Circuit: The PS and PL sections of the ZYNQ core board require multiple voltage power supplies. This invention adopts a multi-level power management scheme to ensure stability. An industrial-grade DC-DC module converts the 24V industrial power supply to 15V, which is then used by a multi-level power management chip to generate the PS core voltage (1.0V), PL core voltage (1.0V), DDR core voltage (1.5V), I / O voltage (3.3V / 2.5V), and auxiliary voltage (1.8V). Each power output is connected in parallel with a 10μF capacitor and a 0.1μF ceramic capacitor for decoupling and to suppress high-frequency noise.

[0074] The ZYNQ core board's PS processing system circuitry: The PS is responsible for adaptive PID control, model predictive control, system management, and human-machine interaction. It has an external 1GB DDR3 SDRAM, connected to the PS's DDR controller via a 16-bit data bus, supporting the PS to run Linux systems or complex control algorithms (such as multivariable decoupling logic). It also has an external 128MB QSPI flash memory, connected to the PS via an SPI interface, used to store the boot program (BOOT.bin) and configuration files for automatic loading upon system power-on. A Gigabit Ethernet (RGMII interface) connection is reserved for connection to industrial switches, supporting the transmission of real-time data (such as control parameters and status feedback) to host computers (such as SCADA systems). Two integrated UART interfaces are used for debugging (such as printing intermediate algorithm variables) and connecting low-speed sensors (such as temperature and humidity modules).

[0075] The ZYNQ core board's PL core interface circuit: The PL is responsible for real-time signal processing and control quantity generation, and needs to be connected to the front-end analog-to-digital converter circuit, the back-end digital-to-analog converter, and the actuator. For high sampling rate sensor signals in industrial feedback (such as vibration acceleration, motor current, 24-bit resolution, 10Ksps~100Ksps sampling rate), the PL is connected to the analog-to-digital converter circuit (ADC) via a parallel bus. The core algorithms of feedback control (PID, Model Predictive Control, MPC) are implemented in hardware within the PL using Verilog / VHDL.

[0076] Analog Control Output Circuit: In feedback control, the analog control output circuit is a crucial link connecting the digital controller and the actuator. Its core function is to convert the digital control quantities (such as binary code or PWM signals) output by the digital controller (ZYNQ's PL section) into continuously adjustable analog signals (voltage or current) to drive the actuator (such as proportional valves, servo motors, and heaters) to achieve precise regulation of the controlled object. This circuit must balance output accuracy, linearity, anti-interference capability, and compatibility with the actuator. The digital controller (ZYNQ's PL section) drives a 16-bit high-voltage converter via an SPI interface, providing ±1LSB INL, ±1LSB DNL performance, and a noise spectral density of 7.5nV / √Hz. To ensure the specified linearity, the digital-to-analog converter uses a precision architecture that requires forced detection buffering of its reference voltage input.

[0077] Gigabit Ethernet communication circuit: Figure 12 This is a gigabit Ethernet communication circuit, where U85 and U86 are electrostatic discharge protection diodes to protect the downstream PHY chip from damage due to electrostatic discharge, and U84 is an HR911130C Ethernet transformer.

[0078] Digital-to-analog converter circuits: such as Figure 13 As shown, the digital-to-analog converter circuit mainly includes the digital-to-analog converter U109 and its peripheral circuits. The digital-to-analog converter U109 uses the ADI AD5760BCPZ chip. The AD5760BCPZ is a true 16-bit voltage output DAC with ±0.5LSB integral nonlinearity (INL), an output noise spectral density of 8nV / √Hz, and a long-term linear error stability of 0.00625LSB. The AD5760BCPZ can ensure that the deviation between the converted analog signal and the ideal value is extremely small. For applications requiring precise analog signal output, such as precision test and measurement instruments and high-end scientific experimental equipment, this can effectively reduce measurement errors and improve the accuracy and reliability of data. The main pins and connection methods of the AD5760BCPZ are as follows:

[0079] SYNC: Level-triggered control input (active low). This is the frame synchronization signal for the input data. When SYNC is low, the input shift register is enabled, and then the data is input to the shift register on the falling edge of the subsequent clock cycle, connecting to the ZYNQ core board.

[0080] SCLK: Serial clock input. Data is read into the shift register on the falling edge of the serial clock input. Data can be transmitted at a maximum rate of 35MHz, connected to the ZYNQ core board.

[0081] SDIN: Serial Data Input. This device has a 24-bit input shift register. Data is read into the register on the falling edge of the serial clock input and connected to the ZYNQ core board.

[0082] SDO: Serial data output, connected to the ZYNQ core board.

[0083] LDAC: Active low loads the DAC logic input. This pin is used to update the DAC register and analog output. When permanently low, the output is updated on the rising edge of SYNC. If LDAC is held high during a write cycle, the input register is updated, but the output is not updated until the falling edge of LDAC. The LDAC pin must not be disconnected and is connected to the ZYNQ core board.

[0084] CLR: Active low. Setting this pin sets the DAC register to a user-defined value and updates the DAC output. The output value depends on the encoding format of the DAC register used: binary or two's complement, connected to the ZYNQ core board.

[0085] RESET: Active low reset. Setting this pin returns the AD5760BCPZ to power-on state when connected to the ZYNQ core board.

[0086] VOUT, INV, RFB: Analog output ports of the AD5760BCPZ, which, when used with the precision operational amplifier AD8675ARMZ, output voltage signals ranging from VREFN to VREFP.

[0087] Capacitors C987 and C988, common-mode inductor L98, transient suppression diode D155, and differential-mode filter capacitors C986 and C990 are differential-mode and common-mode protection circuits designed to adapt to harsh industrial monitoring environments.

[0088] The technical solution of this embodiment is actually applied to a pressure measurement feedback system project, constructing a closed-loop system integrating high-precision pressure sensing, real-time signal processing, and intelligent feedback control. By selecting a ±0.01%FS-level high-precision pressure sensor to collect gas or liquid medium pressure signals, after amplification and filtering by a low-noise signal conditioning module, analog-to-digital conversion is completed by a 24-bit high-speed ADC, and then data calculation and error compensation are performed by an embedded main control unit. Combined with a preset pressure threshold, dynamic feedback is achieved - when the measured pressure deviates from the set range, the system can automatically drive the actuator (such as a regulating valve or pump group) to adjust. At the same time, it supports real-time data display, storage, and remote communication functions.

[0089] Table 1 shows the measured data of a pressure measurement feedback system.

[0090] Table 1. Measured data of a pressure measurement feedback system.

[0091]

[0092]

[0093] After observing 20 sets of data measurements, the highest accuracy of pressure measurement reached 0.012%, or 0.012%, and the highest accuracy of reverse voltage output of the drive actuator reached 0.02%, or 0.02%. These indicators far exceeded the project requirements, ensuring the safety and accuracy of the pressure measurement feedback system.

[0094] 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. A high-precision feedback control circuit for industrial environmental monitoring, characterized in that: It includes analog signal acquisition circuits, digital processing circuits, and analog control output circuits; The analog signal acquisition circuit includes a pre-protection circuit, a sensor interface circuit, a signal conditioning circuit, and an analog-to-digital conversion circuit; it realizes the acquisition, signal conditioning, and analog-to-digital conversion of the sensor's analog signals. The digital processing circuit connects the front-end analog-to-digital converter circuit and the back-end digital-to-analog converter circuit. It mainly includes the ZYNQ core board, which realizes the digital processing of signals and the control of the front-end analog-to-digital converter circuit and the back-end digital-to-analog converter. The analog control output circuit includes a digital-to-analog converter and a gigabit Ethernet communication circuit, which converts the digital control quantity output by the digital processing circuit into a continuously adjustable analog signal to drive the actuator to achieve precise adjustment of the controlled object.

2. The high-precision feedback control circuit for industrial monitoring environment according to claim 1, characterized in that: The pre-protection circuit includes a first-stage surge protection circuit, a second-stage surge protection circuit, and a common-mode and differential-mode suppression circuit connected in sequence.

3. The high-precision feedback control circuit for industrial monitoring environment according to claim 1, characterized in that: The sensor interface circuit is implemented through a relay switching circuit, connecting sensors with different input types and converting them into adjustable voltage signals.

4. The high-precision feedback control circuit for industrial monitoring environment according to claim 1, characterized in that: The signal conditioning circuit includes a follower circuit and a second-order analog filter, which amplifies, filters, isolates, and corrects the nonlinearity of the voltage signal output from the sensor interface circuit.

5. The high-precision feedback control circuit for industrial monitoring environment according to claim 1, characterized in that: The analog-to-digital conversion circuit uses the AD7768BSTZ chip and peripheral circuits to convert the conditioned analog signal output by the signal conditioning circuit into a digital signal.

6. The high-precision feedback control circuit for industrial monitoring environment according to claim 1, characterized in that: The ZYNQ core board includes a PS processing system circuit and a PL core interface circuit, which are connected to the front-end analog-to-digital conversion circuit, the back-end digital-to-analog conversion circuit, and the actuator.

7. The high-precision feedback control circuit for industrial monitoring environment according to claim 1, characterized in that: The analog-to-digital conversion circuit of the analog control output circuit is connected to the digital processing circuit, and also to the detection equipment. The digital control quantity output by the digital processing circuit drives the actuator to make precise adjustments.

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