An oil valve pressure pulse isolation differential acquisition circuit and peak identification method in a strong electromagnetic interference environment

Abstract

This invention belongs to the field of industrial field oil valve pressure monitoring technology, specifically an isolated differential acquisition circuit and peak identification method for oil valve pressure pulses under strong electromagnetic interference environments. The circuit includes a pressure sensor interface, a constant current source excitation circuit, a differential analog-to-digital converter circuit, a slave controller, a hybrid isolation unit, and an analog power switch. The differential analog-to-digital converter circuit is connected to the slave controller via a digital isolation branch, and the slave controller controls the analog power switch via an opto-isolation branch. The peak identification method calculates the idle baseline value and noise amplitude within an idle sampling window and generates an adaptive threshold accordingly. When the pressure sample value meets the conditions of rising trigger, peak hold, falling back confirmation, and stability confirmation, the effective pressure peak value is locked and the event data is output. This invention can reduce sampling drift, glitch false triggering, and missed peak capture, improving the reliability of oil valve pressure short pulse acquisition and identification.

Description

Technical Field

[0001] This invention relates to the field of embedded data acquisition and oil valve status monitoring technology in industrial settings, and particularly to an isolation differential acquisition circuit and peak identification method for short pressure pulses in oil valves under strong electromagnetic interference environments. Background Technology

[0002] In oil valve control, lubrication system monitoring, and industrial fluid control scenarios, it is typically necessary to collect pressure change signals generated during the opening, closing, or oil supply processes of oil valves using pressure sensors. These pressure signals are usually short-duration pressure pulse signals with rapid rise times and significant peak value variations. Accurately acquiring the pressure peak value and the number of effective actuations during oil valve operation is crucial for determining the valve's operating status, ensuring adequate oil supply, and identifying any blockages or leaks in the pipeline.

[0003] Existing oil valve pressure acquisition devices typically place the pressure sensor interface, sensor excitation branch, analog-to-digital converter, and microcontroller on the same acquisition board, lacking a clear isolation zone between the analog acquisition area and the digital control area. In some acquisition devices, the pressure sensor output is directly connected to the analog-to-digital converter in a single-ended manner, or there is a lack of effective isolation between the differential acquisition link and the digital control link. This makes it easy for common-mode interference, ground potential fluctuations, and external spatial radiation interference introduced during long cable transmission to be superimposed on the analog acquisition signal.

[0004] Meanwhile, in existing data acquisition devices, the digital communication terminal of the analog-to-digital converter is usually directly connected to the microcontroller. High-frequency digital noise generated during the high-speed switching of digital clock signals, chip select signals, and data transmission signals can easily couple to the analog acquisition terminal through signal lines, ground lines, or power lines. In some devices, the analog power switch is directly controlled by the microcontroller, and the control link lacks opto-isolation or equivalent isolation structures. During power switching or control signal switching, this can also easily cause disturbances to the pressure sensor excitation branch and the analog-to-digital conversion acquisition branch.

[0005] Furthermore, existing oil valve pressure sensors often employ ordinary voltage power supply or simple current-limiting structures in their excitation circuits, lacking stable constant current excitation and temperature compensation designs. When the ambient temperature changes, the power supply voltage fluctuates, or the sensor cable is long, the sensor excitation current is prone to drift, leading to a deviation in the pressure sensor's output baseline. These structural defects can cause zero-point drift, spikes, abnormal jumps, or false peaks in the short-pulse pressure acquisition signal of the oil valve, affecting the accuracy of subsequent peak identification.

[0006] In terms of signal processing, existing oil valve pressure acquisition schemes typically employ mean filtering, low-pass filtering, or fixed threshold judgment methods to process the pressure sampled values. While these methods can suppress random noise to some extent, for oil valve pressure pulses with short durations and fast rise times, large filtering windows can easily weaken the true peak value and introduce recognition delays; small filtering windows, on the other hand, are insufficient to filter out transient spikes generated under strong electromagnetic interference. Fixed threshold judgment methods also struggle to adapt to changes in ambient noise levels and zero-point drift of the pressure signal. When the threshold is set too low, spikes are easily misjudged as valid oil valve actions; when the threshold is set too high, the true pressure peak value is easily missed.

[0007] Therefore, existing oil valve pressure acquisition devices not only suffer from structural problems such as insufficient isolation between the analog acquisition end and the digital control end, insufficient excitation stability of the pressure sensor, and insufficient anti-interference capability of single-ended or weakly isolated acquisition links, but also face the challenge of balancing anti-interference performance and real-time processing with ordinary filtering and fixed threshold identification. There is an urgent need for an isolated differential acquisition circuit and peak identification method capable of stably acquiring short pulses of oil valve pressure and reliably identifying pressure peaks under strong electromagnetic interference environments. Summary of the Invention

[0008] The purpose of this invention is to provide an isolated differential acquisition circuit and peak identification method for oil valve pressure pulses under strong electromagnetic interference environments. This addresses the problems of sampling drift, spikes, missed peak captures, and the difficulty in balancing anti-interference performance and real-time performance in existing oil valve pressure acquisition devices under strong electromagnetic interference environments. This invention can reduce sampling drift, false spike triggering, and missed peak captures, thereby improving the reliability of short-pulse acquisition and identification of oil valve pressure.

[0009] To achieve the above objectives, the present invention provides an isolation differential acquisition circuit for oil valve pressure pulses under strong electromagnetic interference environment, including a pressure sensor interface, a constant current source excitation circuit, a differential analog-to-digital converter circuit, a slave controller, a hybrid isolation unit, and an analog power switch.

[0010] The excitation terminal of the pressure sensor interface is connected to the constant current source excitation circuit, and the differential signal output terminal of the pressure sensor interface is connected to the differential input terminal of the differential analog-to-digital converter circuit; the constant current source excitation circuit is used to provide a constant excitation current to the oil valve pressure sensor, and the differential analog-to-digital converter circuit is used to sample the differential pressure signal output by the oil valve pressure sensor and output the pressure sample value.

[0011] The differential analog-to-digital converter circuit, constant current source excitation circuit, and analog power switch are located in the analog signal domain, while the slave controller is located in the digital control domain. The hybrid isolation unit is located between the analog signal domain and the digital control domain, and the hybrid isolation unit includes a digital isolation branch and an opto-isolation branch. The digital isolation branch is connected to the digital communication link between the differential analog-to-digital converter circuit and the slave controller, and the opto-isolation branch is connected to the control link between the slave controller and the analog power switch.

[0012] With the above structure, the pressure sensor output signal enters the differential analog-to-digital converter circuit in a differential manner, which can suppress common-mode interference in long cable transmission; the digital communication link of the differential analog-to-digital converter circuit is connected to the slave controller through a digital isolation branch, which can reduce the coupling of digital clock signals and communication signals to the analog acquisition end; the control link of the slave controller to the analog power switch is connected through an opto-isolation branch, which can reduce the disturbance of control signal switching or power switching to the analog signal domain.

[0013] Furthermore, the differential analog-to-digital converter circuit includes multiple differential analog-to-digital converter chips, each of which includes at least two sets of differential sampling channels. The positive and negative input terminals of each differential sampling channel are respectively connected to the two differential output terminals of the corresponding oil valve pressure sensor to form a multi-channel oil valve pressure pulse acquisition link.

[0014] Furthermore, the constant current source excitation circuit includes multiple constant current source branches corresponding to the pressure sampling channels. Each constant current source branch includes a constant current source device, a precision setting resistor, and a temperature compensation diode. The output terminal of the constant current source device is connected to the excitation terminal of the corresponding pressure sensor interface. The precision setting resistor and the temperature compensation diode constitute a feedback regulation branch to reduce the influence of ambient temperature and power supply fluctuations on the excitation current of the pressure sensor.

[0015] Furthermore, the digital isolation branch includes a digital isolator, and at least one of the clock signal line, chip select signal line, data input signal line, and data output signal line of the differential analog-to-digital converter circuit is connected to the serial communication port of the slave controller via the digital isolator.

[0016] Furthermore, the opto-isolation branch includes an opto-isolator, the input terminal of which is connected to the control terminal of the slave controller, the output terminal of which is connected to the control terminal of the analog power switch, and the output terminal of the analog power switch is connected to the power supply terminals of the constant current source excitation circuit and the differential analog-to-digital converter circuit, respectively.

[0017] This invention also provides a method for identifying oil valve pressure pulse peak values ​​based on the above-mentioned isolation differential acquisition circuit. This method is executed by a slave controller and includes the following steps:

[0018] S1. A constant excitation current is provided to the oil valve pressure sensor through a constant current source excitation circuit, and the differential pressure signal output by the oil valve pressure sensor is acquired through a differential analog-to-digital converter circuit to obtain the pressure sampling value of each pressure sampling channel.

[0019] S2. In the idle sampling window when the oil valve is not activated, calculate the idle baseline value and noise amplitude of the corresponding pressure sampling channel based on the continuous pressure sampling values.

[0020] S3. Generate an adaptive rise trigger threshold, adaptive rate of change threshold, adaptive fallback confirmation threshold, and stability threshold for the corresponding pressure sampling channel based on the noise amplitude.

[0021] S4. When the increment of the current pressure sample value relative to the idle baseline value is greater than the adaptive rise trigger threshold, and the rate of change of the current pressure sample value is greater than the adaptive rate of change threshold, the corresponding pressure sampling channel is switched from idle state to rise state.

[0022] S5. In the rising state, the maximum pressure sampling value during the current oil valve pressure pulse process is continuously recorded by the peak holding variable;

[0023] S6. When the current pressure sample value falls back more than the peak hold variable, the corresponding pressure sampling channel is switched to the falling confirmation state.

[0024] S7. When the current pressure sampling value falls back to the vicinity of the idle baseline value and continues to meet the stability confirmation condition, lock the peak value holding variable as the effective pressure peak value of this oil valve pressure pulse, and accumulate one effective oil valve action count.

[0025] Furthermore, the idle baseline value in step S2 is calculated using an exponential smoothing method, and the noise amplitude is calculated using an exponential smoothing value of the deviation between the current pressure sampling value and the idle baseline value.

[0026] Furthermore, in step S3, the adaptive rise trigger threshold, adaptive rate of change threshold, adaptive fallback confirmation threshold, and stability threshold are all dynamically adjusted according to the noise amplitude. When the noise amplitude increases, the adaptive rise trigger threshold, adaptive rate of change threshold, and adaptive fallback confirmation threshold are increased accordingly; when the noise amplitude decreases, the adaptive rise trigger threshold, adaptive rate of change threshold, and adaptive fallback confirmation threshold are decreased accordingly.

[0027] Furthermore, in step S4, the switch from the idle state to the rising state also requires that the triggering condition is met for multiple consecutive sampling cycles, or that the duration of the pressure sampling value after a single trigger is greater than the preset minimum pulse width time, in order to filter out single-point spikes and glitches.

[0028] Furthermore, the stability confirmation conditions in step S7 include:

[0029] The difference between the current pressure sample value and the idle baseline value is less than the stability threshold, and this state continues to reach the preset stable sampling number; after the stability confirmation condition is met, the effective action number of the corresponding pressure sampling channel is incremented by one, and the effective pressure peak value and the effective action number are output as event data.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] First, the present invention adopts a data acquisition structure that combines constant current source excitation with differential analog-to-digital conversion, which can reduce the impact of sensor excitation current drift and common-mode interference on the sampling results and improve the stability of pressure short pulse acquisition.

[0032] Second, the present invention sets up a digital isolation branch and an opto-isolation branch between the analog signal domain and the digital control domain, so that the digital communication link and the analog power control link are isolated respectively, thereby reducing the coupling of digital high-frequency noise, communication noise and control switch noise to the analog acquisition end.

[0033] Third, the present invention establishes an idle baseline value and noise amplitude for each pressure sampling channel within the idle sampling window, and dynamically generates a rising trigger threshold, a rate of change threshold, a falling confirmation threshold, and a stabilization threshold based on the noise amplitude, which can adapt to the zero drift of different channels and changes in on-site noise.

[0034] Fourth, the present invention adopts a state recognition method that combines amplitude increment, rate of change, peak hold, fallback confirmation and stability confirmation. It can capture the peak value of short pressure pulses without relying on large window low-pass filtering, thereby reducing peak attenuation, recognition delay, false triggering of glitch and missed peak capture. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the overall structure of the oil valve pressure pulse acquisition and identification system provided in an embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram of the connection of the hybrid isolation differential acquisition circuit in an embodiment of the present invention.

[0037] Figure 3 This is a schematic diagram of the multi-channel constant current source excitation and differential acquisition structure in an embodiment of the present invention.

[0038] Figure 4 This is a flowchart of the oil valve pressure pulse peak recognition method in an embodiment of the present invention.

[0039] Figure 5This is a waveform diagram of the idle baseline, adaptive threshold, peak hold point, and stable confirmation interval in an embodiment of the present invention.

[0040] Explanation of reference numerals in the attached figures:

[0041] 100 - Isolation differential acquisition circuit; 101 - Pressure sensor interface; 102 - Constant current source excitation circuit; 1021~1028: First~Eighth constant current source branches; 103 - Differential analog-to-digital converter circuit; 1031~1034: First~Fourth differential analog-to-digital converter chips; 104 - Slave controller; 105 - Hybrid isolation unit; 106 - Analog power switch; 107 - Digital isolation branch; 108 - Opto-isolation branch; 109 - Analog signal domain; 110 - Digital control domain; 111 - Communication interface; 113 - Isolation boundary; 200 - Oil valve pressure sensor; 2001~2008: First~Eighth oil valve pressure sensors; 201 - Excitation end; 202 - Differential signal output end; 300 - External master control unit; 301 - Communication link; - Constant current excitation current; I1~I8: Constant current excitation current output from the first to eighth constant current source branches; D1~D8: Differential pressure signal pairs output from the first to eighth oil valve pressure sensors; CH1~CH8: First to eighth differential sampling channels. Detailed Implementation

[0042] The specific embodiments of the present invention will now be described with reference to the accompanying drawings. It should be understood that the following embodiments are only for illustrating the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Without departing from the technical concept of the present invention, those skilled in the art can make equivalent substitutions or adjustments to specific device models, connection methods, and parameters.

[0043] Example 1: Overall Structure and Isolation Differential Acquisition Circuit

[0044] like Figure 1 As shown, this embodiment provides an oil valve pressure pulse acquisition and identification system, which includes an external main control unit 300, a communication link 301, an isolation differential acquisition circuit 100, and an oil valve pressure sensor 200. The external main control unit 300 is connected to the isolation differential acquisition circuit 100 via the communication link 301, and the isolation differential acquisition circuit 100 is connected to the oil valve pressure sensor 200. The isolation differential acquisition circuit 100 is used to perform anti-interference acquisition of the pressure pulse signal output by the oil valve pressure sensor 200, and to obtain the effective pressure peak value and effective number of actions of the oil valve pressure pulse locally.

[0045] The isolated differential acquisition circuit 100 includes a constant current source excitation circuit 102, a differential analog-to-digital converter circuit 103, a slave controller 104, a hybrid isolation unit 105, an analog power switch 106, and a communication interface 111. The constant current source excitation circuit 102 is connected to the excitation terminal 201 of the oil valve pressure sensor 200, the differential analog-to-digital converter circuit 103 is connected to the differential signal output terminal 202 of the oil valve pressure sensor 200, and the slave controller 104 is connected to the differential analog-to-digital converter circuit 103, the hybrid isolation unit 105, and the communication interface 111.

[0046] The external main control unit 300 can be a motherboard, host computer, gateway, or industrial controller; the communication link 301 can be an RS485 bus, CAN bus, or other industrial communication link. It should be noted that the external main control unit 300 and communication link 301 are used to represent the application environment and event data output path of this invention. The core of this invention lies in the isolated differential acquisition circuit 100 and its peak identification method.

[0047] like Figure 2 As shown, in the isolated differential acquisition circuit 100, the differential analog-to-digital converter circuit 103, the constant current source excitation circuit 102, and the analog power switch 106 are located in the analog signal domain 109, and the slave controller 104 is located in the digital control domain 110. An isolation boundary 113 is provided between the analog signal domain 109 and the digital control domain 110. The hybrid isolation unit 105 includes a digital isolation branch 107 and an opto-isolation branch 108.

[0048] The oil valve pressure sensor 200 includes an excitation terminal 201 and a differential signal output terminal 202. The constant current source excitation circuit 102 outputs a constant current excitation current to the excitation terminal 201. During the operation of the oil valve, the oil valve pressure sensor 200 outputs a differential pressure signal, which is input to the differential input terminal of the differential analog-to-digital converter circuit 103 via the differential signal output terminal 202.

[0049] The differential analog-to-digital converter circuit 103 is used to convert the differential pressure signal output by the oil valve pressure sensor 200 into a digital pressure sample value. The serial communication signal of the differential analog-to-digital converter circuit 103 is transmitted to the slave controller 104 via the digital isolation branch 107. In one embodiment, the serial communication signal includes at least one of SCLK, CS, MOSI, and MISO.

[0050] Opto-isolation branch 108 is connected to the control link between slave controller 104 and analog power switch 106. The PO_ON control signal output by slave controller 104 is transmitted to analog power switch 106 via opto-isolation branch 108. The output of analog power switch 106 provides analog power supply VA to constant current source excitation circuit 102 and differential analog-to-digital converter circuit 103 respectively.

[0051] pass Figure 2 As shown in the structure, the digital communication link between the differential analog-to-digital converter circuit 103 and the slave controller 104 is isolated by the digital isolation branch 107, which can reduce the influence of the coupling of digital clock signals and communication signals to the analog signal domain 109; the control link between the slave controller 104 and the analog power switch 106 is isolated by the opto-isolation branch 108, which can reduce the disturbance of control signal flipping or power switching to the analog acquisition end.

[0052] The constant current source excitation circuit 102 is used to provide a constant excitation current to the oil valve pressure sensor 200. In one embodiment, the constant current source excitation circuit 102 includes a constant current source device, a precision setting resistor, and a temperature compensation diode. The constant current source device can be an LM334 or a device with similar constant current output function, and the temperature compensation diode can be a diode with temperature compensation function. The specific models mentioned above are merely examples and are not intended to limit the scope of protection of this invention.

[0053] In this embodiment, the constant current source excitation current can be expressed as:

[0054]

[0055] in, This represents the excitation current of the constant current source. This indicates a precision-set resistor. This indicates the internal reference voltage of the constant current source device. This represents the forward voltage drop of the temperature compensation diode. This indicates the ambient temperature. By selecting appropriate precision setting resistors and temperature compensation diode parameters, the excitation current drift caused by changes in ambient temperature can be reduced, thereby mitigating the impact of pressure sensor output baseline shift with temperature variations.

[0056] The slave controller 104 is used to control the sampling process of the differential analog-to-digital converter circuit 103, receive digital pressure sampling values, and maintain idle baseline values, noise amplitude, adaptive threshold, state variables and peak hold variables for each pressure sampling channel to perform oil valve pressure pulse peak identification.

[0057] Example 2: Multi-channel constant current source excitation and differential acquisition structure

[0058] like Figure 3 As shown, the constant current source excitation circuit 102 includes first to eighth constant current source branches 1021 to 1028, which respectively provide constant current excitation current to the first to eighth oil valve pressure sensors 2001 to 2008. ~ The pressure sensors 2001 to 2008 for the first to eighth oil valves respectively output differential pressure signals. ~ .

[0059] The differential pressure signal D1 output by the first oil valve pressure sensor 2001 is connected to the first differential sampling channel CH1 of the first differential analog-to-digital converter chip 1031; the differential pressure signal D2 output by the second oil valve pressure sensor 2002 is connected to the second differential sampling channel CH2 of the first differential analog-to-digital converter chip 1031; the differential pressure signal D3 output by the third oil valve pressure sensor 2003 is connected to the first differential sampling channel CH3 of the second differential analog-to-digital converter chip 1032; and the differential pressure signal D4 output by the fourth oil valve pressure sensor 2004 is connected to the second differential sampling channel CH4 of the second differential analog-to-digital converter chip 1032. The differential pressure signal D5 output by the fifth oil valve pressure sensor 2005 is connected to the first differential sampling channel CH5 of the third differential analog-to-digital converter chip 1033; the differential pressure signal D6 output by the sixth oil valve pressure sensor 2006 is connected to the second differential sampling channel CH6 of the third differential analog-to-digital converter chip 1033; the differential pressure signal D7 output by the seventh oil valve pressure sensor 2007 is connected to the first differential sampling channel CH7 of the fourth differential analog-to-digital converter chip 1034; and the differential pressure signal D8 output by the eighth oil valve pressure sensor 2008 is connected to the second differential sampling channel CH8 of the fourth differential analog-to-digital converter chip 1034. The first to fourth differential analog-to-digital converter chips 1031 to 1034 are connected to the slave controller 104 via SPI serial communication links, and transmit the pressure sampling values ​​corresponding to each differential sampling channel to the slave controller 104.

[0060] pass Figure 3 As shown in the structure, each oil valve pressure sensor has a corresponding constant current source branch, which is differentially connected to the corresponding differential analog-to-digital converter chip. This reduces the impact of sensor excitation drift and common-mode interference on the sampling results and provides corresponding pressure sampling values ​​for subsequent independent peak identification of each channel.

[0061] Example 3: Idle Baseline, Noise Amplitude, and Adaptive Threshold

[0062] like Figure 4 As shown, the slave controller 104 targets the first Each pressure sampling channel performs a peak identification process. First, the current pressure sampling value is acquired. and read the state variable .in, Indicates the pressure sampling channel number. Indicates the sampling period number.

[0063] For the The pressure sampling channel is set as follows: The pressure sample value obtained in each sampling period is The pressure sampling value of the previous sampling period is The current sampling rate of change It can be represented as:

[0064]

[0065] Slave controller 104 maintains an idle baseline value for each pressure sampling channel. Noise amplitude Adaptive rising trigger threshold Adaptive rate of change threshold Adaptive fallback confirmation threshold Stability threshold State variables and peak hold variables Among them, state variables Including idle state, rising state, and falling confirmation state, peak hold variable Used to record the maximum pressure sampling value of the corresponding pressure sampling channel during a single oil valve pressure pulse.

[0066] When the corresponding pressure sampling channel is in an idle state, it indicates that no valid oil valve pressure pulse has been detected. The slave controller 104 updates the idle baseline value and noise amplitude within the idle sampling window. The idle baseline value represents the current background pressure level of the pressure sampling channel when the oil valve is not activated. Due to temperature drift, power fluctuations, and sensor zero-point offset in industrial environments, the idle baseline value is not fixed and therefore needs to be updated slowly over time.

[0067] The idle baseline value is calculated using an exponential smoothing method, and the calculation formula is as follows:

[0068]

[0069] in, For the first The pressure sampling channel is in the first The idle baseline value for each sampling period. This is the idle baseline value from the previous sampling period. This is the current pressure sample value. is the baseline smoothing coefficient, and ( ).

[0070] Noise amplitude represents the degree of fluctuation of the pressure sample value around the idle baseline value when the pressure sampling channel is idle. The noise amplitude is calculated using the exponentially smoothed value of the deviation between the current pressure sample value and the idle baseline value, as shown in the formula:

[0071]

[0072] in, For the first The pressure sampling channel is in the first Noise amplitude per sampling period The noise amplitude of the previous sampling period. is the noise smoothing coefficient, and ( ).

[0073] Using formulas (3) and (4), the slave controller 104 can establish dynamically updated idle baseline values ​​and noise amplitudes for each pressure sampling channel when the oil valve is not activated. The idle baseline value is used to compensate for zero-point drift, and the noise amplitude is used to reflect the intensity of on-site interference. Compared with fixed zero points and fixed thresholds, this method enables different channels to form independent judgment benchmarks based on their respective sensor status, cable status, and noise environment.

[0074] Slave controller 104 based on noise amplitude Dynamically generate adaptive rising trigger threshold, adaptive rate of change threshold, adaptive falling back confirmation threshold, and stability threshold.

[0075] The adaptive rising trigger threshold is calculated as follows:

[0076]

[0077] in, For the first The pressure sampling channel is in the first An adaptive rising trigger threshold for each sampling period Based on the rising trigger threshold, This is the adjustment coefficient for the rising trigger threshold.

[0078] The adaptive rate of change threshold is calculated as follows:

[0079]

[0080] in, For the first The pressure sampling channel is in the first Adaptive rate of change threshold for each sampling period Based on the threshold rate of change, This is the threshold adjustment coefficient for the rate of change.

[0081] The adaptive fallback confirmation threshold is calculated as follows:

[0082]

[0083] in, For the first The pressure sampling channel is in the first Adaptive fallback confirmation threshold for each sampling period Based on the basic pullback confirmation threshold, The threshold adjustment coefficient is used to confirm the fallback.

[0084] The stability threshold is calculated as follows:

[0085]

[0086] in, For the first The pressure sampling channel is in the first The stability threshold for each sampling period Based on the stability threshold, The threshold adjustment coefficient is used to stabilize the threshold.

[0087] In this way, when the ambient noise amplitude increases, the judgment thresholds are raised accordingly, thereby reducing the false triggering of transient spikes caused by strong electromagnetic interference; when the ambient noise amplitude decreases, the judgment thresholds are lowered accordingly, thereby preventing the short pulses of oil valve pressure with small actual amplitude from being missed.

[0088] Example 4: Peak Hold State Machine

[0089] like Figure 4 As shown, when the pressure sampling channel is in an idle state, the slave controller 104 continuously updates the idle baseline value. and noise amplitude The adaptive threshold is updated based on the noise amplitude. A valid pressure pulse rising edge is determined to have occurred in the pressure sampling channel when the following conditions are met:

[0090]

[0091] and:

[0092]

[0093] Formula (9) indicates that the increment of the current pressure sample value relative to the idle baseline value is greater than the adaptive rise trigger threshold, and Formula (10) indicates that the rate of change of the current pressure sample value is greater than the adaptive rate of change threshold.

[0094] To avoid false triggering due to single-point spikes, in a preferred embodiment, the switch from idle to rising state requires that the trigger condition be met for multiple consecutive sampling cycles, or that the duration of the pressure sampling value after a single trigger is greater than a preset minimum pulse width time. After meeting these conditions, the slave controller 104 switches the corresponding pressure sampling channel from idle to rising state and initializes the peak hold variable. .

[0095] When the pressure sampling channel is in the rising state, the slave controller 104 continuously compares the current pressure sampling value. With peak preservation variable If the following conditions are met:

[0096]

[0097] Then update:

[0098]

[0099] In the rising state, the slave controller 104 does not quickly update the idle baseline value, or reduces the update speed of the idle baseline value, in order to avoid the oil valve pressure pulse itself being mistakenly included in the baseline estimation, thereby affecting the peak value judgment.

[0100] When the current pressure sample value falls relative to the peak value of the variable, the following conditions must be met:

[0101]

[0102] At that time, the slave controller 104 switches the corresponding pressure sampling channel from the rising state to the falling confirmation state.

[0103] When the pressure sampling channel is in a declining confirmation state, the slave controller 104 determines whether the pressure sampling value has fallen back to near the idle baseline value. If the following conditions are met:

[0104]

[0105] If this state continues for a preset number of stable samplings, the current oil valve pressure pulse is considered to have ended. At this point, the slave controller 104 locks the peak hold variable. The effective pressure peak value of this oil valve pressure pulse:

[0106]

[0107] in, Indicates the first The effective pressure peak value of the oil valve pressure pulse in this pressure sampling channel.

[0108] After locking the effective pressure peak, the slave controller 104 increments the effective action count of the corresponding pressure sampling channel and generates event data. The event data includes at least one of the following: channel number, effective pressure peak, effective action count, and sampling time information. Subsequently, the slave controller 104 can send the event data to the external master control unit 300 via the communication interface 111, or store it in a non-volatile memory.

[0109] pass Figure 4 As shown in the process, the slave controller 104 can dynamically update the baseline and noise in the idle state, perform peak hold in the rising state, and determine whether the pressure sampling value has fallen back and stabilized in the falling confirmation state, thereby identifying the effective peak value of the oil valve pressure short pulse without relying on large window low-pass filtering.

[0110] Example 5: Waveform State Relationship

[0111] like Figure 5 As shown, the oil valve pressure sampling value hovers around the idle baseline value when the oil valve is not activated. Slight fluctuations. Idle baseline value. This indicates the background pressure level of the current channel when the oil valve is not activated. The background pressure level can be dynamically updated as temperature, power supply, or sensor zero point changes slowly.

[0112] When the pressure sample value is relative to the idle baseline value The increment exceeds the adaptive rise trigger threshold When the rate of change condition is met, the system determines that the oil valve pressure pulse has entered the rising phase. During the rising phase, the slave controller 104 maintains the variable at its peak value. The maximum value among the pressure samples is continuously recorded and used as the peak hold point.

[0113] Subsequently, when the pressure sample value is relative to the peak hold variable The pullback magnitude meets the adaptive pullback confirmation threshold. At this point, the system determines that the oil valve pressure pulse has entered the descent confirmation phase. When the pressure sampling value falls back to near the idle baseline value and continues to meet the stability threshold within the stable confirmation interval... When the corresponding stability confirmation condition is met, the slave controller 104 locks the effective pressure peak value for this time.

[0114] Figure 5 The stable confirmation interval is used to avoid misjudgments caused by short-term spikes, secondary fluctuations, or sampling jitter. The oil valve pressure pulse is only considered to have ended when the pressure sample value remains near the idle baseline value within a preset number of stable samplings.

[0115] Example 6: Collaborative Working Process under Strong Electromagnetic Interference Environment

[0116] During the actual operation of the oil valve, the switching of the solenoid valve coil may generate transient voltage spikes, the motor driver may generate high-frequency switching noise, the wireless communication module may generate radio frequency interference, and long-distance sensor cables may introduce common-mode interference. These interferences may manifest as instantaneous spikes in the pressure sampling values, slow baseline drift, or random fluctuations.

[0117] This invention first reduces the possibility of interference entering the acquisition link through a hardware-level isolated differential acquisition structure. The oil valve pressure sensor 200 uses a constant current source excitation to reduce measurement errors caused by excitation power supply fluctuations; the output signal of the oil valve pressure sensor 200 enters the differential analog-to-digital converter circuit 103 in a differential manner to suppress common-mode interference; the differential analog-to-digital converter circuit 103 communicates with the slave controller 104 through a digital isolation branch 107 to reduce the high-frequency noise coupling from the digital control domain 110 to the analog signal domain 109; the control link of the slave controller 104 controlling the analog power switch 106 is isolated through an opto-isolation branch 108 to reduce sampling disturbances caused by cross-domain coupling of control signals.

[0118] Building upon hardware-based anti-interference measures, this invention further processes residual interference using an idle baseline, noise amplitude, and an adaptive threshold. The idle baseline value is used to track the current background pressure level of each channel when the oil valve is not activated. The noise amplitude is used to characterize the interference intensity of the current channel. The adaptive threshold is used to dynamically adjust the pressure pulse triggering and fallback confirmation conditions based on the interference intensity.

[0119] When the ambient noise is strong, the noise amplitude increases, and the adaptive rising trigger threshold and adaptive falling confirmation threshold increase accordingly. Single-point spikes and small random fluctuations are less likely to trigger the peak identification process. When the ambient noise is weak, the noise amplitude decreases, and the adaptive threshold decreases accordingly. Short pulses of oil valve pressure with small amplitude but real existence can still be captured.

[0120] Therefore, this invention does not simply rely on large-window low-pass filtering to suppress interference, but rather improves the reliability of identifying effective pressure peak and number of actions under strong electromagnetic interference environment by using a collaborative approach of "isolated differential acquisition circuit + idle baseline exponential smoothing estimation + noise amplitude exponential smoothing estimation + adaptive threshold + peak hold state machine".

[0121] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, modifications or equivalent substitutions can be made to the specific device model, threshold calculation method, sampling frequency, communication interface, and structural layout without departing from the technical concept of the present invention, and all such modifications or equivalent substitutions should be included within the protection scope of the present invention.

Claims

1. An isolation differential acquisition circuit for oil valve pressure pulses under strong electromagnetic interference environment, characterized in that, Includes a pressure sensor interface, a constant current source excitation circuit, a differential analog-to-digital converter circuit, a slave controller, a hybrid isolation unit, and an analog power switch; The excitation terminal of the pressure sensor interface is connected to the constant current source excitation circuit, and the differential signal output terminal of the pressure sensor interface is connected to the differential input terminal of the differential analog-to-digital converter circuit. The differential analog-to-digital converter circuit, the constant current source excitation circuit, and the analog power switch are located in the analog signal domain, while the slave controller is located in the digital control domain. The hybrid isolation unit is disposed between the analog signal domain and the digital control domain. The hybrid isolation unit includes a digital isolation branch and an opto-isolation branch. The digital isolation branch is connected to the digital communication link between the differential analog-to-digital converter circuit and the slave controller. The opto-isolation branch is connected to the control link between the slave controller and the analog power switch. The slave controller includes a storage unit and a peak identification processing unit. The storage unit contains baseline variables, noise amplitude variables, adaptive threshold variables, state variables, and peak hold variables corresponding to each pressure sampling channel. The peak identification processing unit identifies the peak value of the oil valve pressure pulse based on the pressure sampling value.

2. The isolated differential acquisition circuit according to claim 1, characterized in that, The differential analog-to-digital converter circuit includes multiple differential analog-to-digital converter chips. Each differential analog-to-digital converter chip includes at least two sets of differential sampling channels. The positive input terminal and negative input terminal of each differential sampling channel are respectively connected to the two differential output terminals of the corresponding oil valve pressure sensor to form a multi-channel oil valve pressure pulse acquisition link.

3. The isolated differential acquisition circuit according to claim 1, characterized in that, The constant current source excitation circuit includes multiple constant current source branches corresponding to the pressure sampling channels. Each constant current source branch includes a constant current source device, a precision setting resistor, and a temperature compensation diode. The output terminal of the constant current source device is connected to the excitation terminal of the corresponding pressure sensor interface. The precision setting resistor and the temperature compensation diode constitute a feedback adjustment branch.

4. The isolated differential acquisition circuit according to claim 1, characterized in that, The digital isolation branch includes a digital isolator, and at least one of the clock signal line, chip select signal line, data input signal line, and data output signal line of the differential analog-to-digital converter circuit is connected to the serial communication port of the slave controller via the digital isolator.

5. The isolated differential acquisition circuit according to claim 1, characterized in that, The opto-isolation branch includes an opto-isolator. The input terminal of the opto-isolator is connected to the control terminal of the slave controller, and the output terminal of the opto-isolator is connected to the control terminal of the analog power switch. The output terminal of the analog power switch is connected to the power supply terminals of the constant current source excitation circuit and the differential analog-to-digital converter circuit, respectively.

6. A method for identifying oil valve pressure pulse peak values ​​based on the isolation differential acquisition circuit described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. A constant excitation current is provided to the oil valve pressure sensor through a constant current source excitation circuit, and the differential pressure signal output by the oil valve pressure sensor is acquired through a differential analog-to-digital converter circuit to obtain the pressure sampling value of each pressure sampling channel. S2. In the idle sampling window when the oil valve is not activated, calculate the idle baseline value and noise amplitude of the corresponding pressure sampling channel based on the continuous pressure sampling values. S3. Generate an adaptive rise trigger threshold, adaptive rate of change threshold, adaptive fallback confirmation threshold, and stability threshold for the corresponding pressure sampling channel based on the noise amplitude. S4. When the increment of the current pressure sample value relative to the idle baseline value is greater than the adaptive rise trigger threshold, and the rate of change of the current pressure sample value is greater than the adaptive rate of change threshold, the corresponding pressure sampling channel is switched from idle state to rise state. S5. In the rising state, the maximum pressure sampling value during the current oil valve pressure pulse process is continuously recorded by the peak holding variable; S6. When the current pressure sample value falls back more than the peak hold variable, the corresponding pressure sampling channel is switched to the falling confirmation state. S7. When the current pressure sampling value falls back to the vicinity of the idle baseline value and continues to meet the stability confirmation condition, lock the peak value holding variable as the effective pressure peak value of this oil valve pressure pulse.

7. The method for identifying oil valve pressure pulse peak values ​​according to claim 6, characterized in that, The idle baseline value in step S2 is calculated using an exponential smoothing method, and the noise amplitude is calculated using the exponential smoothing value of the deviation between the current pressure sampling value and the idle baseline value.

8. The method for identifying oil valve pressure pulse peak values ​​according to claim 6, characterized in that, In step S3, the adaptive rise trigger threshold, adaptive rate of change threshold, adaptive fallback confirmation threshold, and stability threshold are all dynamically adjusted according to the noise amplitude. When the noise amplitude increases, the adaptive rise trigger threshold, adaptive rate of change threshold, and adaptive fallback confirmation threshold are increased accordingly; when the noise amplitude decreases, the adaptive rise trigger threshold, adaptive rate of change threshold, and adaptive fallback confirmation threshold are decreased accordingly.

9. The method for identifying oil valve pressure pulse peak values ​​according to claim 6, characterized in that, In step S4, the switch from the idle state to the rising state also requires that the triggering condition is met for multiple consecutive sampling cycles, or that the duration of the pressure sampling value after a single trigger is greater than the preset minimum pulse width time, in order to filter out single-point spikes and glitch.

10. The method for identifying oil valve pressure pulse peak values ​​according to claim 6, characterized in that, The stability confirmation conditions in step S7 include: The difference between the current pressure sample value and the idle baseline value is less than the stability threshold, and this state continues to reach the preset stable sampling number; after the stability confirmation condition is met, the effective action number of the corresponding pressure sampling channel is incremented by one, and the effective pressure peak value and the effective action number are output as event data.

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