Contactor function detection method and system based on multi-parameter fusion

Abstract

The invention discloses a contactor function detection method and system based on multi-parameter fusion, and belongs to the technical field of contactor detection. The method comprises the following steps: acquiring a voltage signal, a current signal and a temperature signal of the contactor in real time; based on a pre-established dynamic threshold value correction model, according to the currently collected temperature signal and current signal, dynamically correcting the voltage sampling comparison threshold value and the voltage and current change rate ratio threshold value; calculating a voltage-current change rate ratio based on the voltage signal and the current signal, and comparing the voltage-current change rate ratio with a corrected voltage-current change rate ratio threshold to obtain a first comparison result; voltage signals at the two ends of the contactor are sampled and compared to obtain a voltage sampling comparison value, and the voltage sampling comparison value is compared with the corrected voltage sampling comparison threshold to obtain a second comparison result; and performing fusion judgment according to the first comparison result and the second comparison result to determine whether the function of the contactor is normal or not.

Description

Technical Field

[0001] This application relates to the field of contactor testing technology, specifically to a contactor function testing method and system based on multi-parameter fusion. Background Technology

[0002] In industrial production and logistics handling scenarios, forklifts, as core handling equipment, directly impact personnel safety and production efficiency through their operational safety. The power output and operational control of a forklift rely on a DC contactor in its motor controller. This component controls the opening and closing of contacts via a control coil, enabling the connection, disconnection, and switching of the circuit between the DC power supply and the load. It is a crucial electrical component ensuring the stable operation of the power system. During forklift operation, malfunctions in the motor controller contactor (such as adhesion or poor contact) can directly lead to safety hazards such as loss of control of the forklift's power system and abnormal operation, seriously threatening the safety of personnel and equipment.

[0003] Current industry methods for detecting forklift contactors have significant limitations: they typically rely on single parameters such as voltage or current for judgment, which can easily lead to misjudgments under complex and variable forklift operating conditions (such as sudden load changes and system voltage fluctuations), making it impossible to distinguish between genuine contactor faults and normal operating interference. Furthermore, because they ignore the physical characteristics of DC contactors, such as their internal resistance and contact states changing significantly with operating temperature and current, traditional methods use fixed, uncompensated judgment thresholds. This results in the detection system being unable to accurately identify early faults or potential anomalies (such as slight adhesion or increased contact resistance) under extreme conditions such as high temperature and high current, leading to missed detections or false alarms. In addition, existing detection solutions do not effectively link with the forklift's overall safety system. Even if a fault is detected, it cannot trigger emergency stops, power cut-offs, or other safety measures in a timely manner, leaving only a passive response to the consequences of the fault and failing to achieve proactive safety protection, ultimately failing to meet the safety requirements of forklift operations.

[0004] Therefore, developing a contactor function detection solution with adaptive working conditions, high detection accuracy, and active safety protection has become a key requirement for solving current technical pain points and improving forklift operation safety. Summary of the Invention

[0005] Therefore, this application is proposed to address the problems and needs existing in the prior art. This application aims to construct a multi-dimensional, highly reliable detection system, combined with dynamic adaptive correction of detection thresholds, to solve the problems of poor anti-interference capability, insufficient detection accuracy, and lack of adaptive capability in existing technologies. This will achieve active safety protection for forklift electrical systems, ultimately providing forklifts with an active safety solution based on predictive diagnostics. The purpose of this application is achieved through the following technical solutions:

[0006] In a first aspect, embodiments of this application provide a contactor function detection method based on multi-parameter fusion, comprising the following steps:

[0007] Real-time acquisition of voltage, current, and temperature signals from the contactor;

[0008] Based on a pre-established dynamic threshold correction model, the voltage sampling comparison threshold and the voltage-current rate of change ratio threshold are dynamically corrected according to the currently acquired temperature and current signals.

[0009] Based on the voltage and current signals, the voltage-current rate of change ratio is calculated and compared with the corrected voltage-current rate of change ratio threshold to obtain a first comparison result.

[0010] The voltage signals at both ends of the contactor are sampled and compared to obtain a voltage sampling comparison value, which is then compared with a corrected voltage sampling comparison threshold to obtain a second comparison result.

[0011] The first comparison result and the second comparison result are combined to determine whether the contactor is functioning normally.

[0012] In the aforementioned contactor function detection method based on multi-parameter fusion, the dynamic threshold correction model is obtained in the following way:

[0013] Obtain calibration data of the contactor under different temperature and current conditions;

[0014] Based on the calibration data, a correlation model is established to reflect the changes in voltage sampling comparison threshold and voltage-current rate of change ratio threshold with temperature and current.

[0015] In the aforementioned contactor function detection method based on multi-parameter fusion, the acquisition of calibration data includes:

[0016] At multiple temperature points, voltage response data of the contactor under different operating voltages and current disturbances were collected.

[0017] Based on the voltage response data, a multidimensional calibration model is constructed to characterize the electrical characteristics of the contactor in relation to temperature and current.

[0018] In the aforementioned contactor function detection method based on multi-parameter fusion, the calculation of the voltage-current change rate ratio includes:

[0019] Differentiate the voltage signal and the current signal respectively to obtain the voltage change rate and the current change rate;

[0020] Calculate the ratio of the voltage change rate to the current change rate to obtain the voltage-current change rate ratio.

[0021] In the above-mentioned contactor function detection method based on multi-parameter fusion, the step of fusing and judging based on the first comparison result and the second comparison result includes:

[0022] When the first comparison result indicates that the voltage-current change rate ratio exceeds its corresponding threshold, and the second comparison result indicates that the voltage sampling comparison value exceeds its corresponding threshold, the contactor is determined to be malfunctioning.

[0023] In the aforementioned contactor function detection method based on multi-parameter fusion, after determining that the contactor function is abnormal, the method further includes:

[0024] Triggering a linkage response with the forklift's overall vehicle safety control system, the linkage response including at least one of fault alarm, power cut-off, or emergency stop protection.

[0025] In the aforementioned contactor function testing method based on multi-parameter fusion, the calibration data is obtained through laboratory experimental calibration or through learning from historical health data during equipment operation.

[0026] In the aforementioned contactor function detection method based on multi-parameter fusion, the multidimensional calibration model is implemented through a lookup table method or a polynomial regression model.

[0027] Secondly, embodiments of this application provide a contactor function detection system based on multi-parameter fusion, used to implement the aforementioned contactor function detection method based on multi-parameter fusion, comprising the following modules:

[0028] The signal acquisition module is used to acquire the voltage, current and temperature signals of the contactor in real time.

[0029] The dynamic threshold correction module is used to output the dynamically corrected voltage sampling comparison threshold and voltage-current change rate ratio threshold based on the currently acquired temperature and current signals and a pre-established dynamic threshold correction model.

[0030] The first comparison module is used to calculate the voltage-current rate of change ratio, compare it with the corrected voltage-current rate of change ratio threshold, and output the first comparison result.

[0031] The second comparison module is used to sample and compare the voltage signals at both ends of the contactor to obtain the voltage sampling comparison value, and compare it with the corrected voltage sampling comparison threshold to output the second comparison result.

[0032] The fusion judgment module is used to output a judgment result on whether the contactor function is normal based on the first comparison result and the second comparison result.

[0033] In the aforementioned contactor function detection system based on multi-parameter fusion, the system further includes a calibration modeling module and a safety execution module; the calibration modeling module is used to establish the dynamic threshold correction model based on the contactor calibration data; the safety execution module is used to execute a linkage response with the forklift vehicle safety control system when the fusion judgment module outputs a judgment result indicating that the contactor function is abnormal; the linkage response includes at least one of fault alarm, power cut-off, or emergency stop protection.

[0034] Compared with the prior art, the beneficial effects of the present invention are at least as follows:

[0035] This application presents a contactor function detection method and system based on multi-parameter fusion. By integrating two core detection dimensions—voltage-to-current ratio (du / di) detection and voltage sampling comparison at both ends of the contactor—and combining them with a temperature compensation mechanism, a multi-parameter collaborative judgment system is constructed. The two parameters complement and verify each other, effectively distinguishing between real faults and operating condition interference (such as load sudden changes and voltage fluctuations). Under common complex operating conditions of forklifts, the stability, anti-interference ability, and reliability of the detection results are significantly improved. Through laboratory calibration or learning from historical health data, a dynamic threshold correction model based on temperature and current parameters is established. This model can dynamically and adaptively correct the voltage sampling comparison threshold and the du / di threshold according to the real-time collected temperature and current signals. It fully considers the changes in the contactor's electrical characteristics with temperature and current, ensuring that the judgment threshold always matches the actual working state of the contactor. Compared with traditional fixed threshold detection methods, the fault identification lead time is extended by 3 to 5 work cycles, allowing sufficient time for fault handling and reducing the probability of safety accidents from the source.

[0036] By deeply integrating precise fault detection results with the forklift's overall safety control system, a closed-loop protection mechanism of "detection-judgment-response" is formed. This proactive protection mode completely changes the passive situation of traditional detection solutions that "only detect but do not respond," minimizing the safety risks of forklift contactor failures and significantly improving the safety level and operational reliability of the forklift motor controller and even the entire vehicle. The dynamic threshold correction model can be built through laboratory calibration or learning from historical health data, supporting multiple common forklift power supply voltage levels such as 24V, 36V, 48V, and 80V, and is suitable for detecting DC contactors of different brands and models. Meanwhile, the system hardware structure is simple and cost-effective, and can be directly integrated into existing forklift motor controllers without significant modifications to the original forklift structure. This facilitates the upgrading and retrofitting of existing forklifts and the mass production and integration of new forklifts, demonstrating strong practical application value and promising prospects for widespread adoption. Attached Figure Description

[0037] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof.

[0038] Figure 1 This is a flowchart illustrating a contactor function detection method based on multi-parameter fusion provided in an embodiment of this application.

[0039] Figure 2 This is a schematic diagram of the structure of a contactor function detection system based on multi-parameter fusion provided in an embodiment of this application;

[0040] Figure 3 This is a schematic diagram of the voltage sampling signal conditioning and comparison output circuit of this application. Detailed Implementation

[0041] Hereinafter, exemplary embodiments according to this application will be described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only a part of the embodiments of this application, and this application is not limited to the exemplary embodiments described herein. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this invention.

[0042] It should be noted that, in the description of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. The terms "first," "second," etc., in this application are used to distinguish similar objects and are not used to describe a specific order or sequence.

[0043] Example 1

[0044] To address the problems of the existing technology mentioned in the background section, this embodiment provides a contactor function detection method based on multi-parameter fusion. This method is primarily applied to the function detection of DC contactors in forklift motor controllers, and can accurately identify faults such as contactor adhesion and poor contact, thus ensuring the overall safety of the forklift. Figure 1 As shown, the specific implementation process is as follows:

[0045] (a) First, conduct laboratory calibration: establish a dynamic threshold correction model.

[0046] The dynamic threshold correction model is obtained in the following way:

[0047] Obtain calibration data of the contactor under different temperature and current conditions;

[0048] Based on calibration data, a correlation model is established to reflect the changes in voltage sampling comparison threshold and voltage-current rate of change ratio threshold with temperature and current.

[0049] The dynamic threshold correction model is the core foundation for achieving dynamic adaptive adjustment of the detection threshold. Its establishment process requires obtaining sufficient data through laboratory calibration and completing the modeling, as detailed below:

[0050] Setting up a calibration experimental platform: The DC contactor of the model to be tested is placed in a programmable temperature chamber. The temperature chamber can be precisely adjusted to cover the actual working environment of a forklift (-40℃~80℃). The input terminal of the contactor is connected to a programmable DC power supply to simulate different battery voltage levels (24V, 36V, 48V, 80V, etc., common forklift power supply voltages). The output terminal is connected to a controllable electronic load, which can accurately apply small-amplitude current disturbances ΔI (ΔI range is 0.5A~5A, step size 0.5A). At the same time, a voltage sensor (measurement accuracy ±0.1V) is connected in parallel across the contactor, and a Hall current sensor (measurement accuracy ±0.05A) is connected in series. A PT100 thermistor (temperature measurement accuracy ±0.5℃) is attached to the surface of the contactor. All sensor signals are connected to a data acquisition card (sampling rate 1kHz).

[0051] Acquiring calibration data includes:

[0052] At multiple temperature points, voltage response data of the contactor under different operating voltages and current disturbances were collected.

[0053] Based on voltage response data, a multidimensional calibration model is constructed to characterize the relationship between the electrical characteristics of the contactor and temperature and current.

[0054] Specifically, temperature gradient setting: adjust the temperature of the chamber to multiple temperature points T (such as -40℃, -20℃, 0℃, 20℃, 40℃, 60℃, 80℃) in sequence, and collect data after each temperature point T has been stable for 30 minutes to ensure that the contactor temperature is consistent with the ambient temperature;

[0055] Voltage and current disturbance combination test: At each temperature point T, the output voltage U of the programmable power supply is set to 24V, 36V, 48V, and 80V respectively, corresponding to each voltage level. At the same time, under each (T, U) combination, a small amplitude current disturbance ΔI of 0.5A, 1A, 1.5A, ..., 5A is applied sequentially through a controllable electronic load, with each disturbance lasting 1 second.

[0056] Response data recording: The voltage response ΔU across the contactor is recorded synchronously by the data acquisition card under each current disturbance, and the contact resistance R=ΔU / ΔI is calculated. At the same time, parameters such as the current temperature T, applied voltage U, and current disturbance ΔI are recorded to form a massive calibration data set (R, T, U, ΔI).

[0057] Correlation model construction: The model is constructed using a lookup table method or a multinomial regression model. Specifically, the multinomial regression model is used to fit the massive calibration data to a surface and establish the correlation equation between the contact current R and the temperature T and voltage U: R = a + b*T + c*U + d*T² + e*T*U + f*U² (where a, b, c, d, e, and f are coefficients obtained by fitting using the least squares method, and the goodness of fit R² ≥ 0.95).

[0058] Based on the contact resistance correlation model, the correlation model u=g(T,I) between voltage sampling comparison threshold and temperature T and current I is derived: According to the voltage-current characteristics of the contactor during normal operation, combined with the safety threshold requirements under different working conditions, the normal voltage range corresponding to each (T,I) combination is determined through experiments, and then a continuous threshold model is obtained by fitting.

[0059] Similarly, the voltage-to-current ratio (du / di, a physical quantity describing the numerical relationship between the voltage and current rates of change in a circuit, where du is the instantaneous change in voltage and di is the instantaneous change in current at the corresponding moment, and the ratio of the two can reflect the circuit impedance change characteristics caused by the state of the device under test, thus serving as a key dynamic characteristic for judging the functional state of the device under test) is derived as a correlation model between temperature T and current I: du / di = f(T, I). By analyzing the ratio of voltage to current in the calibration data and combining the characteristic differences under fault conditions, a threshold model of du / di under normal operating conditions is fitted.

[0060] In addition, calibration data can also be obtained by learning from historical health data during equipment operation: collect long-term operating data (voltage, current, temperature, du / di value, etc.) of the same model of contactor under normal operating conditions, remove abnormal data, and then use the same modeling method as laboratory calibration to build a dynamic threshold correction model, which is suitable for scenarios where laboratory calibration cannot be performed.

[0061] (ii) Real-time signal acquisition

[0062] Voltage signal acquisition: A voltage transformer (1:1000 ratio, bandwidth 10Hz~1MHz) is used to acquire the voltage signal u(t) between the contactor input terminal Vin and the output terminal BUS. The signal is then processed by a signal conditioning circuit (such as...). Figure 3 (As shown) The voltage signal is converted into a standard analog signal of 0-3.3V and connected to the ADC acquisition channel of the MCU, with the sampling frequency set to 1kHz;

[0063] Current signal acquisition: A closed-loop Hall current sensor (range 0~500A, response time ≤1μs) is connected in series in the contactor circuit to acquire the circuit current i(t). The sensor outputs an analog signal of 0~5V, which is filtered by an RC filter circuit (cutoff frequency 100Hz) and then connected to another ADC channel of the MCU. The sampling frequency is consistent with the voltage signal (1kHz).

[0064] Temperature signal acquisition: The PT100 thermistor is attached to the surface of the contactor housing with thermally conductive adhesive. A three-wire temperature measurement circuit is connected to the analog input port of the MCU and powered by a constant current source (constant current 1mA). The current temperature T(t) is calculated based on the resistance change, and the temperature measurement period is 100ms.

[0065] (iii) Dynamic threshold correction

[0066] The MCU calls the pre-stored dynamic threshold correction model (u=g(T,I) and du / di=f(T,I)), reads the currently acquired temperature signal T(t) and current signal i(t) in real time, and substitutes them into the correction model to calculate the dynamically corrected voltage sampling comparison threshold under the current operating condition. and du / di threshold For example, when the current temperature T=40℃ and current I=50A are collected, the model calculations yield the following results. = 8V = 0.02V / A, enabling adaptive adjustment (dynamic compensation) of the judgment threshold according to the operating conditions (current operating current and temperature), so that the detection standard always matches the actual physical state of the contactor, thereby significantly improving the detection accuracy across the entire operating range;

[0067] (iv) Parameter calculation and comparison

[0068] The calculation of the voltage-current rate of change ratio includes:

[0069] Differentiate the voltage signal and the current signal respectively to obtain the rate of change of voltage and the rate of change of current.

[0070] Calculate the ratio of the voltage change rate to the current change rate to obtain the voltage-current change rate ratio;

[0071] Specifically, the voltage-to-current rate of change ratio (du / di) is calculated and compared:

[0072] Differential operation: The MCU performs numerical differentiation processing on the acquired voltage signal u(t) and current signal i(t), and calculates the rate of change using the first-order backward difference method: du / dt= [u(n) - u(n-1)] / Δt, di / dt= [i(n) - i(n-1)] / Δt, where Δt is the sampling period (1ms) and n is the current sampling point number;

[0073] Ratio calculation: Divide the rate of change of voltage by the rate of change of current to obtain du / di=(du / dt) / (di / dt), which is used as the first detection parameter;

[0074] Threshold comparison: Compare the calculated du / di with the dynamically corrected... If du / di > or du / di <- (Considering changes in positive and negative directions), the first comparison result is "abnormal", otherwise it is "normal";

[0075] Voltage sampling comparison and result judgment:

[0076] Voltage Conditioning: The voltage signal u(t) acquired from both ends of the contactor is conditioned by a voltage divider circuit (1:100 ratio) to convert the high voltage signal into a low voltage signal recognizable by the MCU. After passing through an active filter circuit (to suppress 50Hz power frequency interference), the voltage sampling comparison value is obtained. ;

[0077] Threshold comparison: With dynamic correction If a comparison is made, > or <0.8 (Set according to the normal operating voltage fluctuation range of the contactor), then the second comparison result is "abnormal", otherwise it is "normal";

[0078] (v) Multi-parameter fusion judgment

[0079] The fusion judgment based on the first comparison result and the second comparison result includes:

[0080] When the first comparison result indicates that the voltage-current change rate ratio exceeds its corresponding threshold, and the second comparison result indicates that the voltage sampling comparison value exceeds its corresponding threshold, the contactor is determined to be malfunctioning.

[0081] The fusion judgment adopts a "double anomaly" logic: only when the first comparison result is "anomaly" (du / di exceeds its threshold) and the second comparison result is "anomaly" (the voltage sampling comparison value exceeds its threshold), is it determined that the contactor function is abnormal; this logic can effectively exclude misjudgments when a single parameter is interfered. For example, when the forklift load suddenly changes and causes an instantaneous current fluctuation, du / di may briefly exceed the threshold, but the voltage sampling comparison value is still normal. At this time, it is determined as "normal" to avoid mis-triggering the safety response; when the contactor has an adhesion fault, it will simultaneously cause du / di and the voltage sampling comparison value to exceed the threshold, ensuring the accuracy of the fault determination.

[0082] Among them, after determining that the contactor function is abnormal, it also includes:

[0083] Trigger the linkage response with the forklift vehicle safety control system, and the linkage response includes at least one of fault alarm, power cut-off or emergency stop protection.

[0084] Specifically, after determining that the contactor function is abnormal, the MCU immediately sends a fault signal (such as fault code 0x0012, representing abnormal contactor function) to the forklift vehicle safety control system through the CAN bus, triggering at least one of the following linkage responses:

[0085] Fault alarm: The forklift dashboard displays the fault code "CONT-ERR", and at the same time, the audible and visual alarm device is started (the buzzer frequency is 1kHz, and the red alarm light flashes at a frequency of 2Hz) to remind the operator to handle it in time;

[0086] Power cut-off: The safety control system controls the motor controller to cut off the power output, prohibits the contactor from sucking in again, and prevents the fault from expanding;

[0087] Emergency stop protection: If the forklift is in a driving or operating state when the fault occurs, the safety control system triggers the emergency stop mechanism, controls the braking system to slow down to a stop slowly (to avoid sudden braking causing the goods to fall), and ensures the safety of personnel and equipment.

[0088] Embodiment 2

[0089] This embodiment provides a contactor function detection system based on multi-parameter fusion, which is used to implement the above-mentioned contactor function detection method based on multi-parameter fusion. This system is installed inside the forklift motor controller and is communicatively connected to the vehicle safety control system, as Figure 2 shown, and the specific structure is as follows:

[0090] This system includes a signal acquisition module, a calibration modeling module, a dynamic threshold correction module, a first comparison module, a second comparison module, a fusion judgment module and a safety execution module. Each module is connected by a PCB board, and the core control unit uses an STM32H7 series MCU. The functions and implementation details of each module are as follows:

[0091] The signal acquisition module includes the following units:

[0092] Voltage acquisition unit: It consists of a voltage transformer (model such as VT-01, input voltage 0~100V, output voltage 0~100mV), voltage divider resistors (R1=100kΩ, R2=1kΩ) and filter capacitor (C1=0.1μF). The output signal of the voltage transformer is divided and filtered before being connected to the ADC1 channel of the MCU to realize the acquisition of voltage signal u(t);

[0093] Current acquisition unit: A Hall current sensor (model such as ACS758-500B, range 0~500A, output 0~5V) is connected in series in the main circuit of the contactor. The sensor output terminal is connected in series with an RC filter circuit (R3=1kΩ, C2=1μF) and connected to the ADC2 channel of the MCU to complete the acquisition of the current signal i(t).

[0094] Temperature acquisition unit: It consists of a PT100 thermistor, a constant current source circuit (using a chip such as REF200 to provide a constant current of 1mA) and a differential amplifier circuit (using a chip such as INA128). The amplified temperature signal is connected to the ADC3 channel of the MCU to realize the acquisition of temperature T(t).

[0095] Calibration and modeling module: The hardware part includes sensors and data acquisition interfaces shared with the signal acquisition module, and is additionally equipped with an SD card storage unit (such as model W25Q64, storage capacity 64MB) for storing laboratory calibration data or equipment historical health data; the software part is integrated into the MCU, including data reading functions, multinomial regression fitting algorithms and model storage functions. By executing the calibration program, it completes the construction and storage of the dynamic threshold correction model, and the model parameters can be updated via the CAN bus;

[0096] The dynamic threshold correction module, whose core is the model calculation unit inside the MCU, receives real-time temperature T(t) and current i(t) data from the signal acquisition module by calling the stored dynamic threshold correction model (u=g(T,I) and du / di=f(T,I)) and performing threshold correction calculations; the calculation result (the corrected value) is then used to calculate the threshold correction. and The data is sent to the second comparison module and the first comparison module respectively via the internal data bus, and the operation period is consistent with the sampling period (1ms).

[0097] The first comparison module includes a differential operation unit and a threshold comparison unit. The differential operation unit is implemented by the MCU's internal digital signal processing (DSP) module, calculating du / dt and di / dt by executing a first-order backward differential algorithm, and then obtaining du / di through division. The threshold comparison unit uses a voltage comparator (such as LM311) to compare the du / di analog signal output from the DSP module with the signal output from the dynamic threshold correction module. The signals are compared, and the output digital value "1" (abnormal) or "0" (normal) is the first comparison result, which is sent to the fusion judgment module;

[0098] The second comparison module consists of a voltage conditioning unit and a threshold comparison unit. The voltage conditioning unit includes a voltage divider circuit and an active filter circuit (built using an OP07 operational amplifier) ​​to step down and filter the acquired voltage signal u(t) to obtain the voltage sampling comparison value. The threshold comparison unit uses a dual-limit voltage comparator (such as the LM339) to... With dynamic correction Perform an upper and lower limit comparison, if If the value exceeds the threshold range, output "1" (abnormal); otherwise output "0" (normal), which is the second comparison result, and send it to the fusion judgment module.

[0099] Fusion Judgment Module: Employs AND gate circuits (e.g., 74LS08) and MCU-assisted judgment: The AND gate receives the first comparison result and the second comparison result. When both results are "1", it outputs a preliminary abnormal signal. The MCU performs anti-jitter processing on the preliminary abnormal signal (continuously detects for 2-3 sampling cycles; if the abnormal signal persists, the fault is confirmed), and finally outputs the contactor function status judgment result (normal / abnormal), which is sent to the safety execution module.

[0100] Safety execution module: includes a CAN communication unit and a drive unit. The CAN communication unit uses a CAN transceiver (such as TJA1050) to connect to the CAN bus of the forklift's overall safety control system and send fault signals and status information. The drive unit consists of a relay (such as HF3FF / 012-1ZS) and a power amplifier circuit (using a transistor such as 2N2222). When it receives an abnormal signal from the fusion judgment module, it drives the relay to activate, triggering the fault alarm device (buzzer, alarm light), controlling the power cut-off switch to disconnect the contactor main circuit, and sending an emergency stop signal to the braking system to achieve a safety linkage response.

[0101] The system workflow is as follows:

[0102] After the system is powered on, it first performs initialization: the calibration modeling module loads the pre-stored dynamic threshold correction model, the signal acquisition module completes sensor self-test, and each comparison module and fusion judgment module is reset to the initial state;

[0103] The signal acquisition module collects voltage u(t), current i(t), and temperature T(t) data in real time and sends them to the dynamic threshold correction module and the first and second comparison modules every 1ms (acquisition frequency);

[0104] The dynamic threshold correction module calculates the dynamic threshold based on real-time T(t) and i(t) and sends it to the corresponding comparison module;

[0105] The first comparison module calculates du / di and compares it with its dynamically corrected threshold. The second comparison module completes voltage sampling comparison and threshold judgment, and outputs the comparison results respectively.

[0106] The fusion judgment module performs logical operations and debouncing on the two comparison results, and outputs the judgment result.

[0107] If the judgment result is abnormal, the safety execution module will link with the forklift safety control system through the CAN bus to perform operations such as fault alarm, power cut-off, and emergency stop protection; if the judgment result is normal, the above process will continue to cycle.

[0108] This system achieves accurate detection and safe linkage of contactor functions through the collaborative work of multiple modules, solving the problems of poor anti-interference ability and insufficient accuracy of traditional detection methods, and is suitable for the complex and ever-changing working conditions of forklifts.

[0109] Those skilled in the art will understand that the specific functions and operations of each module and each unit in the module in the contactor function detection system based on multi-parameter fusion of this embodiment have been described in detail in the contactor function detection method based on multi-parameter fusion described in Embodiment 1 above. Therefore, the repeated description will be omitted here.

[0110] The basic principles of this application have been described above with reference to specific embodiments. It should be understood that the specific details disclosed above are for illustrative and illustrative purposes only, and are not intended to limit the scope of protection of this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A contactor function detection method based on multi-parameter fusion, characterized in that, Includes the following steps: Real-time acquisition of voltage, current, and temperature signals from the contactor; Based on a pre-established dynamic threshold correction model, the voltage sampling comparison threshold and the voltage-current rate of change ratio threshold are dynamically corrected according to the currently acquired temperature and current signals. Based on the voltage and current signals, the voltage-current rate of change ratio is calculated and compared with the corrected voltage-current rate of change ratio threshold to obtain a first comparison result. The voltage signals at both ends of the contactor are sampled and compared to obtain a voltage sampling comparison value, which is then compared with a corrected voltage sampling comparison threshold to obtain a second comparison result. The first comparison result and the second comparison result are combined to determine whether the contactor is functioning normally.

2. The method as described in claim 1, characterized in that, The dynamic threshold correction model is obtained through the following method: Obtain calibration data of the contactor under different temperature and current conditions; Based on the calibration data, a correlation model is established to reflect the changes in voltage sampling comparison threshold and voltage-current rate of change ratio threshold with temperature and current.

3. The method as described in claim 2, characterized in that, The acquisition of calibration data includes: At multiple temperature points, voltage response data of the contactor under different operating voltages and current disturbances were collected. Based on the voltage response data, a multidimensional calibration model is constructed to characterize the electrical characteristics of the contactor in relation to temperature and current.

4. The method as described in claim 1, characterized in that, The calculation of the voltage-current rate of change ratio includes: Differentiate the voltage signal and the current signal respectively to obtain the voltage change rate and the current change rate; Calculate the ratio of the voltage change rate to the current change rate to obtain the voltage-current change rate ratio.

5. The method as described in claim 1, characterized in that, The step of fusing the first comparison result and the second comparison result includes: When the first comparison result indicates that the voltage-current change rate ratio exceeds its corresponding threshold, and the second comparison result indicates that the voltage sampling comparison value exceeds its corresponding threshold, the contactor is determined to be malfunctioning.

6. The method as described in claim 1 or 5, characterized in that, After determining that the contactor is malfunctioning, the following steps are also included: Triggering a linkage response with the forklift's overall vehicle safety control system, the linkage response including at least one of fault alarm, power cut-off, or emergency stop protection.

7. The method as described in claim 2, characterized in that, The calibration data is obtained through laboratory experiments or by learning from historical health data during equipment operation.

8. The method as described in claim 3, characterized in that, The multidimensional calibration model is implemented using a lookup table method or a multinomial regression model.

9. A contactor function detection system based on multi-parameter fusion, used to implement the method as described in any one of claims 1-8, characterized in that, Includes the following modules: The signal acquisition module is used to acquire the voltage, current and temperature signals of the contactor in real time. The dynamic threshold correction module is used to output the dynamically corrected voltage sampling comparison threshold and voltage-current change rate ratio threshold based on the currently acquired temperature and current signals and a pre-established dynamic threshold correction model. The first comparison module is used to calculate the voltage-current rate of change ratio, compare it with the corrected voltage-current rate of change ratio threshold, and output the first comparison result. The second comparison module is used to sample and compare the voltage signals at both ends of the contactor to obtain the voltage sampling comparison value, and compare it with the corrected voltage sampling comparison threshold to output the second comparison result. The fusion judgment module is used to output a judgment result on whether the contactor function is normal based on the first comparison result and the second comparison result.

10. The system as described in claim 9, characterized in that, The system further includes a calibration modeling module and a safety execution module; the calibration modeling module is used to establish the dynamic threshold correction model based on the calibration data of the contactor; the safety execution module is used to execute a linkage response with the forklift vehicle safety control system when the fusion judgment module outputs a judgment result indicating that the contactor is malfunctioning; the linkage response includes at least one of fault alarm, power cut-off, or emergency stop protection.

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