Three-phase terminal temperature monitoring fault early warning method and system for heavy truck motor

Abstract

The present application relates to the technical field of vehicle electrical system monitoring, and more particularly to a heavy truck motor three-phase terminal temperature monitoring fault early warning method and system, comprising: acquiring the temperature signal of the three-phase output terminal of the heavy truck motor and converting it into three-phase real-time temperature values, and acquiring the current working current value of the motor; based on the preset multi-level absolute temperature threshold, performing graded protection judgment on the three-phase real-time temperature values; based on the current working current value, generating a corresponding dynamic temperature difference threshold; based on the three-phase real-time temperature values, calculating the real-time temperature difference characteristic values between the three phases and the change rate thereof within a preset time window; comparing the real-time temperature difference characteristic values with the preset dynamic / static temperature difference threshold, and comparing the change rate with the preset rate threshold, judging whether there is a phase with abnormal connection state, and generating an early warning signal; the present application is used for temperature monitoring of the heavy truck large-current OT / bolt terminal connection structure, and realizes real-time monitoring and early fault warning of the connection state.

Description

Technical Field

[0001] This invention relates to the field of vehicle electrical system monitoring technology, and in particular to a method and system for fault early warning of three-phase terminal temperature monitoring of heavy-duty truck motors. Background Technology

[0002] In the electric drive system of heavy-duty trucks, the motor controller and the drive motor are connected by a large-section cable with extremely high operating current, with rated current exceeding 500 Arms and peak current even exceeding 900 Arms. Currently, this connection point is generally connected using OT terminals or bolt-type terminals with strong overcurrent capacity and high mechanical reliability. However, due to long-term exposure to extreme current surges, severe mechanical vibrations, thermal cycling stress, and possible fluctuations in installation processes, the contact resistance of this connection point is at risk of increasing. Increased contact resistance can lead to abnormal overheating of the connection point, which may cause terminal erosion, wiring harness melting, or even fire accidents in severe cases, making it one of the high-risk failure points of the electric drive system.

[0003] To address the aforementioned risks, existing technologies lack effective online monitoring solutions. Current vehicle control systems typically only monitor the temperatures of critical components such as the motor windings and IGBT modules, neglecting the equally critical external physical connection points (i.e., OT / bolt terminal connections), creating a safety monitoring blind spot. Furthermore, while integrated temperature sensor solutions exist for quick-connect connectors, their structure, installation method, and applicable electrical environment are completely different from the OT / bolt terminals commonly used in heavy-duty trucks. Quick-connect connectors have sealed structures and dedicated sensor mounting slots, while OT / bolt terminals are rigid, unsealed, and subjected to high-stress mechanical connections, making existing integrated temperature measurement solutions unsuitable for direct transplantation or adaptation. Moreover, even when temperature data is available, existing temperature difference diagnostic methods often rely on fixed threshold comparisons, failing to consider the impact of motor load current variations on the normal temperature rise of the connection point, leading to false alarms under low-current conditions and missed alarms under high-current conditions. Additionally, existing methods are mostly reactive alarms, unable to identify early deterioration trends in the connection status before a fault occurs.

[0004] Therefore, in view of the problems of existing technologies, such as the lack of effective monitoring methods leading to blind spots in safety monitoring, the inability to directly transplant or adapt existing integrated temperature measurement solutions, and the single diagnostic logic, there is an urgent need to propose a temperature monitoring and early warning solution that can directly and reliably address the high-current OT / bolt terminal connection structure of heavy-duty trucks, so as to achieve real-time monitoring of connection status and early fault warning. Summary of the Invention

[0005] In order to overcome the technical problems of existing technologies being unable to directly and reliably monitor the temperature of high-current OT / bolt terminal connection points of heavy trucks, and the lack of early warning due to the simplistic diagnostic logic.

[0006] The technical solution of this invention is: a method for fault early warning of three-phase terminal temperature monitoring of heavy-duty truck motors, comprising the following steps: S1: Real-time acquisition of temperature signals from the U-phase, V-phase, and W-phase output terminals of the heavy-duty truck motor, and conversion of the temperature signals into three-phase real-time temperature values ​​T_u, T_v, and T_w, while simultaneously acquiring the current operating current value I of the motor; S2: Based on preset multi-level absolute temperature thresholds, graded protection judgment is performed on the real-time temperature values ​​of the three phases; S3: Based on the current operating current value I, generate a dynamic temperature difference threshold ΔT_dyn_th corresponding to the operating current value; S4: Based on the real-time three-phase temperature values ​​T_u, T_v, and T_w, calculate the real-time temperature difference characteristic value ΔT between the three phases, and calculate the rate of change dΔT / dt of the real-time temperature difference characteristic value ΔT within a preset time window; S5: Compare the real-time temperature difference characteristic value ΔT with the preset static temperature difference threshold ΔT_static_th and the dynamic temperature difference threshold ΔT_dyn_th, and compare the rate of change dΔT / dt with the preset rate threshold. Based on the comparison results, comprehensively determine whether there is a phase with abnormal connection status, and generate a corresponding warning signal.

[0007] Preferably, the method for generating the dynamic temperature difference threshold ΔT_dyn_th in step S3 is as follows: Based on the pre-calibrated current-temperature difference baseline model ΔT_base(I), the reference temperature difference value ΔT_base under the current operating current value I is calculated. The dynamic temperature difference threshold ΔT_dyn_th = α·ΔT_base, where α is a reliability coefficient greater than 1, and its specific value is pre-calibrated according to the system safety margin requirements.

[0008] Preferably, the method for comprehensive judgment in step S5 includes: Condition A: If the real-time temperature difference characteristic value ΔT is greater than the static temperature difference threshold ΔT_static_th, then it is determined that the phase with the highest temperature corresponding to the real-time temperature difference characteristic value ΔT has a serious connection anomaly. Condition B: If the real-time temperature difference characteristic value ΔT is greater than the dynamic temperature difference threshold ΔT_dyn_th and the duration exceeds the first preset time, it is determined that the phase with the highest temperature has an early risk of connection state degradation. Condition C: If the rate of change dΔT / dt is greater than the preset rate threshold and the duration exceeds the second preset time, then the connection status is determined to be rapidly deteriorating; When any one of condition A, condition B, or condition C is met, a corresponding warning signal is generated.

[0009] Preferably, the real-time temperature difference characteristic value ΔT is the difference between the maximum and minimum values ​​of the three-phase temperatures, i.e., ΔT = max(T_u, T_v, T_w) - min(T_u, T_v, T_w).

[0010] Preferably, in step S1, the temperature signals of the U-phase, V-phase, and W-phase output terminals are acquired simultaneously through synchronous sampling.

[0011] Preferably, a sensor self-diagnostic step is also included: Determine whether the voltage value of each temperature signal is within the preset effective physical range. If it exceeds the effective physical range, determine that the corresponding temperature sensing unit or transmission line has an open circuit or short circuit fault.

[0012] A three-phase terminal temperature monitoring system for heavy-duty truck motors, used to implement the above method, includes: An integrated sensor module includes three temperature sensing units, which are respectively disposed on the U-phase, V-phase, and W-phase output terminal blocks of the heavy truck motor. Each temperature sensing unit is thermally coupled to the conductive component of its corresponding output terminal block to sense the temperature of the conductive component and generate a temperature signal. A signal transmission harness is connected to the integrated sensor module for transmitting the temperature signal; A centralized signal processing and control module, connected to the signal transmission harness, is arranged inside the motor controller housing. The centralized signal processing and control module includes: The current acquisition unit is used to acquire the current operating current value I of the motor. The signal acquisition unit is used to receive and process the temperature signal, and convert it into three-phase real-time temperature values ​​T_u, T_v, and T_w. The storage unit is used to store the preset multi-level absolute temperature threshold, static temperature difference threshold ΔT_static_th, rate threshold, and current-temperature difference baseline model ΔT_base(I); The arithmetic unit is connected to the current acquisition unit, the signal acquisition unit, and the storage unit, respectively, and is configured to perform the following operations: Based on the current operating current value I and the current-temperature difference baseline model ΔT_base(I), a dynamic temperature difference threshold ΔT_dyn_th is generated; Calculate the real-time temperature difference characteristic value ΔT between the three phase temperatures; Calculate the rate of change dΔT / dt of the real-time temperature difference characteristic value ΔT within a preset time window; The real-time temperature difference characteristic value ΔT is compared with the static temperature difference threshold ΔT_static_th and the dynamic temperature difference threshold ΔT_dyn_th, and the rate of change dΔT / dt is compared with the rate threshold. A diagnostic output unit, connected to the arithmetic unit, is used to generate and output a corresponding warning signal based on the comparison result.

[0013] Preferably, the output terminal block includes a housing, and the housing has mounting windows corresponding to the positions of each phase conductive component. The temperature sensing unit is embedded in the mounting window, and the temperature sensing surface of the temperature sensing unit is in contact with the surface of the conductive component. The mounting window is filled with potting compound, and the potting compound covers the temperature sensing unit and the root of its lead.

[0014] Preferably, the signal transmission harness is a shielded twisted pair cable, comprising three signal lines and one conductor serving as a common reference ground. The three signal lines are respectively connected to three temperature sensing units, and the common ground is connected to the system signal reference ground along with the grounding terminals of the three temperature sensing units. The shielding layer of the shielded twisted pair cable is grounded at a single point at the interface of the centralized signal processing and control module.

[0015] Preferably, the signal acquisition unit includes: A multi-channel precision constant current source is used to provide independent excitation current for the three temperature sensing units; A multi-channel synchronous sampling analog-to-digital converter is used to synchronously acquire the voltage signals generated by the three temperature sensing units in response to the excitation current.

[0016] The beneficial effects of this invention are: 1. This invention fills the critical safety monitoring blind spot in the electric drive system of heavy trucks, realizing direct and online temperature monitoring of the high-current OT / bolt terminal connection points of heavy trucks, solving the safety hazard of this critical part being in a state of no monitoring for a long time; by directly integrating the temperature sensing unit into the terminal block and thermally coupling it with the conductive component, it can capture abnormal temperature rises caused by loosening, corrosion, aging, etc. in real time and accurately, providing basic data guarantee for the safe operation of the system. 2. This invention proposes a dynamic temperature difference diagnosis method that adapts to different operating conditions, thereby improving diagnostic accuracy. This invention abandons the traditional fixed-threshold temperature difference judgment method and introduces a dynamic temperature difference threshold based on real-time current. Through a pre-calibrated current-temperature difference baseline model ΔT_base(I), a temperature difference judgment standard ΔT_dyn_th = α·ΔT_base is dynamically generated to adapt to different load conditions. This mechanism solves the technical problems of false alarms under low current conditions and missed alarms under high current conditions caused by fixed thresholds, enabling the diagnostic logic to truly reflect changes in connection status rather than the impact of load changes, thus improving diagnostic accuracy and environmental adaptability. 3. This invention achieves a technological leap from post-event alarms to pre-event predictions. Specifically, by calculating the rate of change of temperature difference dΔT / dt, this invention can capture the dynamic process of contact resistance increasing rapidly. When the temperature difference has not yet exceeded the static or dynamic threshold, if the rate of change of temperature difference continues to exceed the rate threshold, the early deterioration trend of the connection status can be identified in advance and an early warning can be issued. This predictive diagnostic capability can advance the fault detection time, buy valuable time for the driver to safely stop or perform maintenance, and transform the maintenance mode from post-event inspection to predictive health management. 4. This invention constructs a multi-dimensional integrated hierarchical early warning system. Specifically, it organically combines static threshold exceedance judgment, dynamic threshold exceedance judgment, and rate of change trend judgment, designing differentiated response mechanisms for different stages of connection state degradation: rate of change trend judgment is used to identify early rapid degradation, dynamic threshold judgment is used to identify mid-term slow degradation, and static threshold judgment is used to identify late-stage severe faults. This hierarchical early warning system achieves full-cycle coverage from fault incubation to fault occurrence, avoiding the limitations of a single criterion and providing differentiated handling strategies for the vehicle controller. 5. This invention provides a highly reliable engineering implementation solution. In terms of sensor integration, a windowed embedding + potting structure is adopted, allowing the sensor's temperature-sensing surface to directly contact the conductive components, ensuring accurate temperature measurement. Simultaneously, the potting compound solves the problems of mechanical fixation in high-vibration environments, electrical insulation in high-voltage environments, and moisture and contamination prevention in harsh environments, providing an integrated engineering solution. Regarding system architecture, a passive sensor + remote centralized processing architecture is adopted. Precision constant current sources, ADCs, MCUs, and other circuits are placed inside an environmentally friendly controller, while high-temperature resistant PT sensors are placed at harsh terminals, improving overall system reliability. In terms of signal transmission, shielded twisted-pair cable and single-point grounding technology are used to effectively suppress strong electromagnetic interference, ensuring the faithful transmission of weak temperature signals.

[0017] 6. This invention constructs a complete system-level solution. Its creativity is not only reflected in the independent contributions of each technical feature, but also in the synergistic effect of hardware integration and diagnostic algorithms. Specifically, the windowed potting integrated structure designed specifically for OT terminals provides the hardware foundation for high-precision temperature sensing, while the dynamic temperature difference threshold generation method based on real-time current and the temperature difference change rate trend judgment algorithm make full use of the high-quality data obtained from this hardware foundation. The two work together to achieve predictive diagnosis of early degradation of connection status. Its technical effect goes beyond the scope of simple temperature monitoring and realizes the leap from passive response to active prevention. Attached Figure Description

[0018] Figure 1 The diagram shown is a schematic representation of the overall architecture of the three-phase terminal temperature monitoring system for heavy-duty truck motors according to the present invention. Figure 2 The diagram shows the integrated installation of the temperature sensing unit of the three-phase terminal temperature monitoring system for heavy-duty truck motors of the present invention on the motor terminal block. Figure 3 The diagram shown is a schematic block diagram of the signal processing circuit at the controller end of the three-phase terminal temperature monitoring system for heavy-duty truck motors of the present invention. Figure 4 The diagram shown is a flowchart of the method for monitoring and warning of faults in the three-phase terminals of a heavy-duty truck motor according to the present invention. Explanation of reference numerals in the attached drawings: 101, output terminal block; 102, conductive component; 103, thin-film platinum resistance thermometer; 104, epoxy resin potting compound; 105, signal transmission cable. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Example 1: Please see Figure 1 , Figure 2 , Figure 3 and Figure 4 This invention provides an embodiment of a method for fault early warning of three-phase terminal temperature monitoring in heavy-duty truck motors, comprising the following steps: S1: Real-time acquisition of temperature signals from the U-phase, V-phase, and W-phase output terminals of the heavy-duty truck motor, and conversion of the temperature signals into three-phase real-time temperature values ​​T_u, T_v, and T_w, while simultaneously acquiring the motor's current operating current value I; This step uses temperature sensing units deployed on each phase terminal to perceive the actual temperature of the conductive component 102, and ensures the time consistency of the three-phase temperature data through synchronous sampling technology, providing a foundation for subsequent accurate analysis; S2: Based on preset multi-level absolute temperature thresholds, the three-phase real-time temperature values ​​are classified for protection judgment. This step serves as a basic safety redundancy, comparing the real-time temperature of each phase with the warning threshold, derating threshold, and shutdown threshold, and executing corresponding protection actions to ensure system safety under extreme conditions. S3: Based on the current operating current value I, generate a dynamic temperature difference threshold ΔT_dyn_th corresponding to the operating current value; this step introduces an adaptive operating condition mechanism, which dynamically adjusts the temperature difference judgment standard according to the real-time current, avoiding the misjudgment problem of fixed threshold under variable load conditions. S4: Based on the real-time three-phase temperature values ​​T_u, T_v, and T_w, calculate the real-time temperature difference characteristic value ΔT between the three phases, and calculate the rate of change dΔT / dt of the real-time temperature difference characteristic value ΔT within a preset time window; this step not only focuses on the static amplitude of the temperature difference, but also on its dynamic trend, providing a basis for predictive diagnosis. S5: Compare the real-time temperature difference characteristic value ΔT with the preset static temperature difference threshold ΔT_static_th and dynamic temperature difference threshold ΔT_dyn_th, and compare the rate of change dΔT / dt with the preset rate threshold. Based on the comparison results, comprehensively determine whether there is a phase with abnormal connection status and generate a corresponding warning signal. This step achieves accurate identification and graded warning of different stages of connection status degradation through multi-dimensional fusion judgment.

[0021] Furthermore, the method for generating the dynamic temperature difference threshold ΔT_dyn_th in step S3 is as follows: based on the pre-calibrated current-temperature difference baseline model ΔT_base(I), the reference temperature difference value ΔT_base under the current operating current value I is calculated, and the dynamic temperature difference threshold ΔT_dyn_th = α·ΔT_base, where α is a reliability coefficient greater than 1, and its specific value is pre-calibrated according to the system safety margin requirements; this current-temperature difference baseline model is based on thermodynamic principles, and the normal temperature rise at the connection point is proportional to the square of the current. The maximum allowable interphase temperature difference baseline under different currents can be pre-calibrated through bench experiments to ensure the scientific nature and accuracy of the dynamic threshold.

[0022] Furthermore, the comprehensive judgment method in step S5 includes: Condition A: If the real-time temperature difference characteristic value ΔT is greater than the static temperature difference threshold ΔT_static_th, then it is determined that the phase with the highest temperature corresponding to the real-time temperature difference characteristic value ΔT has a serious connection anomaly. Condition B: If the real-time temperature difference characteristic value ΔT is greater than the dynamic temperature difference threshold ΔT_dyn_th and the duration exceeds the first preset time, then it is determined that the phase with the highest temperature has an early risk of connection state degradation. Condition C: If the rate of change dΔT / dt is greater than the preset rate threshold and the duration exceeds the second preset time, then the connection status is determined to be rapidly deteriorating. When any one of conditions A, B, or C is met, a corresponding warning signal is generated. This hierarchical judgment logic is designed with differentiated response mechanisms for different stages of connection state degradation (slow degradation, rapid degradation, and severe failure), achieving complete coverage from fault prediction to fault alarm.

[0023] Furthermore, the real-time temperature difference characteristic value ΔT is the difference between the maximum and minimum values ​​of the three-phase temperatures, i.e., ΔT = max(T_u, T_v, T_w) - min(T_u, T_v, T_w). Using the maximum temperature difference as the characteristic value can most intuitively reflect the degree of imbalance of the three-phase temperatures, which is convenient for locating abnormal phases.

[0024] Furthermore, in step S1, the temperature signals of the U-phase, V-phase, and W-phase output terminals are acquired simultaneously through synchronous sampling. Synchronous sampling can eliminate the calculation error caused by the inconsistency in the three-phase temperature sampling time due to current transients, ensuring the accuracy of temperature difference calculation.

[0025] Furthermore, it also includes sensor self-diagnostic steps: The voltage value of each temperature signal is determined to be within the preset effective physical range. If it exceeds the effective physical range, the corresponding temperature sensing unit or transmission line is determined to have an open circuit or short circuit fault. This step ensures the reliability of the monitoring system itself and the validity of the data.

[0026] A three-phase terminal temperature monitoring system for heavy-duty truck motors, used to implement the above method, includes: The integrated sensor module includes three temperature sensing units, which are respectively set on the U-phase, V-phase, and W-phase output terminal blocks 101 of the heavy truck motor. Each temperature sensing unit is thermally coupled to the conductive component 102 of its corresponding output terminal block 101 to sense the temperature of the conductive component 102 and generate a temperature signal. The signal transmission harness connects to the integrated sensor module and is used to transmit temperature signals. A centralized signal processing and control module, connected to the signal transmission harness, is located inside the motor controller housing. The centralized signal processing and control module includes: The current acquisition unit is used to acquire the current operating current value I of the motor. The signal acquisition unit is used to receive and process temperature signals, converting them into three-phase real-time temperature values ​​T_u, T_v, and T_w. The storage unit is used to store the preset multi-level absolute temperature threshold, static temperature difference threshold ΔT_static_th, rate threshold, and current-temperature difference baseline model ΔT_base(I); The arithmetic unit is connected to the current acquisition unit, the signal acquisition unit, and the storage unit, and is configured to perform the following operations: Based on the current operating current value I and the current-temperature difference baseline model ΔT_base(I), a dynamic temperature difference threshold ΔT_dyn_th is generated; Calculate the real-time temperature difference characteristic value ΔT between the three phase temperatures; Calculate the rate of change dΔT / dt of the real-time temperature difference characteristic value ΔT within a preset time window; The real-time temperature difference characteristic value ΔT is compared with the static temperature difference threshold ΔT_static_th and the dynamic temperature difference threshold ΔT_dyn_th, and the rate of change dΔT / dt is compared with the rate threshold. The diagnostic output unit, connected to the arithmetic unit, is used to generate and output corresponding warning signals based on the comparison results.

[0027] The system architecture employs a passive sensor + remote centralized processing approach. It places the sophisticated signal processing circuitry within the relatively environmentally friendly controller, while placing the high-temperature resistant, highly reliable temperature sensing unit at the harsh terminal connection points. This achieves functional separation and synergy, enhancing the overall reliability of the system. Furthermore, the output terminal block 101 includes a housing, on which mounting windows are provided corresponding to the positions of each phase conductive component 102. The temperature sensing unit is embedded in the mounting window, and the temperature sensing surface of the temperature sensing unit is in contact with the surface of the conductive component 102. The mounting window is filled with potting compound, which covers the temperature sensing unit and the root of its lead wire. This integrated structure realizes direct thermal coupling between the sensor and the conductive component 102, ensuring the accuracy of temperature sensing. At the same time, the potting process simultaneously solves multiple problems such as sensor fixation, high voltage insulation, and moisture and dirt prevention in high vibration environments, making it an integrated engineering solution.

[0028] Furthermore, the signal transmission harness is a shielded twisted pair cable, comprising three signal lines and one conductor serving as a common reference ground. The three signal lines are connected to the three temperature sensing units one by one, and the common ground is connected to the system signal reference ground along with the grounding terminals of the three temperature sensing units. The shielding layer of the shielded twisted pair cable is grounded at a single point at the interface of the centralized signal processing and control module. This wiring method can effectively suppress electromagnetic interference and ensure reliable transmission of weak temperature signals in strong electromagnetic environments.

[0029] Furthermore, the signal acquisition unit includes: Multiple precision constant current sources are used to provide independent excitation current for the three temperature sensing units; A multi-channel synchronous sampling analog-to-digital converter is used to synchronously acquire the voltage signals generated by the three temperature sensing units in response to the excitation current. The use of independent constant current source excitation and synchronous sampling ADC can eliminate errors caused by crosstalk between channels and inconsistent sampling time, ensuring the comparability of three-phase temperature data.

[0030] Through the above steps, this invention, by directly integrating the temperature sensing unit into the terminal block and thermally coupling it with the conductive component 102, can capture abnormal temperature rises caused by loosening, corrosion, aging, etc., in real time and accurately, providing basic data assurance for the safe operation of the system; this invention proposes a dynamic temperature difference diagnosis method that adapts to operating conditions, improving diagnostic accuracy; this invention dynamically generates a temperature difference judgment standard ΔT_dyn_th = adapted to different load conditions through a pre-calibrated current-temperature difference baseline model ΔT_base(I). α·ΔT_base; This mechanism solves the technical problems of false alarms easily occurring under low current conditions and false alarms easily occurring under high current conditions with fixed thresholds. It enables the diagnostic logic to truly reflect changes in connection status rather than the effects of load changes, improving diagnostic accuracy and environmental adaptability. This invention can capture the dynamic process of accelerating increase in contact resistance by calculating the rate of change of temperature difference dΔT / dt. When the temperature difference has not yet exceeded the static or dynamic threshold, if the rate of change of temperature difference continues to exceed the rate threshold, the early deterioration trend of the connection status can be identified in advance and an early warning can be issued. This predictive diagnostic capability can advance the fault detection time, buy valuable time for the driver to safely stop or perform maintenance, and transform the maintenance mode from post-inspection to predictive health management. This invention organically combines static threshold over-limit judgment, dynamic threshold over-limit judgment, and rate of change trend judgment, and designs differentiated response mechanisms for different stages of connection status deterioration: the rate of change trend judgment is used to identify early rapid deterioration, and the dynamic threshold judgment... This hierarchical early warning system is used to identify slow degradation in the mid-term and to identify severe late-stage faults using static threshold judgment. It achieves full-cycle coverage from fault incubation to fault occurrence, avoiding the limitations of a single criterion and providing differentiated handling strategies for the vehicle controller. In terms of sensor integration, the invention employs a windowed embedding + potting structure, allowing the sensor's temperature-sensing surface to directly contact the conductive component 102 to ensure accurate temperature measurement. Simultaneously, the potting compound solves the problems of mechanical fixation under high vibration, electrical insulation under high pressure, and moisture and contamination prevention in harsh environments, providing an integrated engineering solution. Regarding system architecture, it adopts a passive sensor + remote centralized processing architecture, placing the precision constant current source, ADC, MCU, and other circuits inside the environmentally friendly controller, while placing the high-temperature resistant PT sensor at the harsh terminal, improving overall system reliability. In terms of signal transmission, shielded twisted-pair cable and single-point grounding technology are used to effectively suppress strong electromagnetic interference and ensure the faithful transmission of weak temperature signals.

[0031] Example 2: Optionally, this embodiment provides a specific implementation process for a method for monitoring and warning of faults in the temperature of three-phase terminals of a heavy-duty truck motor; this method is applicable to the temperature monitoring and connection status diagnosis of the three-phase output terminals of the motor controller and the drive motor connected by OT terminals or bolt-type terminals in the electric drive system of a heavy-duty truck.

[0032] In this embodiment, the method includes the following steps: Step S101: Data Synchronization Acquisition and Temperature / Current Acquisition After the system is powered on and initialized, the main control unit controls multiple precision constant current sources to simultaneously provide stable excitation current to the temperature sensing units of the U, V, and W phases. In this embodiment, the temperature sensing unit uses a PT1000 platinum resistance thermometer, and the excitation current is set to 1mA. The high-precision analog-to-digital converter (ADC) synchronously samples the voltage response signals of the three sensing units to ensure that the timestamps of the three-phase temperature data are strictly consistent. The main control unit calculates the real-time resistance value of each phase PT1000 based on the voltage sampling values ​​V_u, V_v, V_w and the known excitation current I_ex (1mA) using the formula R_x = V_x / I_ex. Then, based on the PT1000 calibration table or using the formula R = R_0(1 + AT + BT^2) (where R_0 is the resistance value at 0℃, and A and B are temperature coefficients), it calculates the accurate real-time temperature values ​​T_u, T_v, and T_w. At the same time, the main control unit obtains the current effective value of the motor's operating current I_rms from the vehicle controller or motor controller via the Controller Area Network (CAN) bus.

[0033] Step S102: Absolute temperature graded protection The real-time temperature values ​​of each phase obtained in step S101 are compared with the multi-level absolute temperature thresholds pre-stored in the main control unit. In this embodiment, three threshold levels are set: warning threshold T_warn = 90℃, power derating threshold T_limit = 105℃, and safety shutdown threshold T_shutdown = 120℃. The comparison logic is as follows: If the temperature of any phase exceeds T_warn but does not exceed T_limit, a "connection point temperature too high warning" message is generated and reported to the instrument display via the CAN bus; If the temperature of any phase exceeds T_limit but does not exceed T_shutdown, a "power derating request" signal is sent to the vehicle controller to request limiting the motor output power and control the temperature rise trend. If the temperature of any phase exceeds T_shutdown, a safety shutdown action will be triggered immediately, and the motor controller will be controlled to cut off the high voltage output through hard-wired signals or CAN messages to protect the system safety. This step serves as a basic safety redundancy, ensuring that the system can respond promptly in extreme situations.

[0034] Step S103: Calculation of Adaptive Dynamic Temperature Difference Threshold under Operating Conditions The core of this step lies in dynamically adjusting the temperature difference judgment standard based on the real-time operating current to avoid misjudgment under variable load conditions with a fixed threshold. First, based on thermodynamic principles, the temperature rise of the connection point under normal operating conditions is proportional to the square of the current, that is, the maximum normal interphase temperature difference ΔT_normal is linearly related to I^2. The maximum allowable interphase temperature difference baseline model ΔT_base(I) under different currents is pre-calibrated through bench experiments. In this embodiment, the calibration data forms a two-dimensional lookup table. To simplify the description, a quadratic polynomial fitting is used: ΔT_base(I) = k·I^2 + c, where k and c are empirical constants obtained by fitting experimental data, for example, k = 0.0002, c = 2.0 (unit: ℃, I is in A). Based on the real-time collected current I_rms, the reference temperature difference value ΔT_base = k·I_rms^2 + c under the current operating condition is calculated; then the dynamic temperature difference threshold ΔT_dyn_th = α·ΔT_base is generated, where α is the reliability coefficient, with a value range of 1.2 to 1.5. In this embodiment, α = 1.3 is taken to reserve a safety margin.

[0035] Step S104: Multi-dimensional temperature difference feature extraction First, calculate the maximum temperature difference of the three phases as the real-time temperature difference characteristic value: ΔT_max = max(T_u, T_v,T_w) - min(T_u, T_v, T_w), and record the phase with the highest temperature, Ph_max. Next, the rate of change of ΔT_max within a preset time window is calculated. In this embodiment, the time window is set to 10 seconds, and the rate of change is calculated using sliding window linear regression or simple difference method: dΔT / dt = [ΔT_max(t) - ΔT_max(t-10)] / 10, with the unit being ℃ / second.

[0036] Step S105: Comprehensive logical judgment and early warning The ΔT_max and dΔT / dt obtained in step S104 are compared with the preset static temperature difference threshold ΔT_static_th, the dynamic temperature difference threshold ΔT_dyn_th generated in step S103, and the preset rate threshold. In this embodiment, the static temperature difference threshold ΔT_static_th is set to 25℃ (corresponding to severe connection abnormality), and the rate threshold is set to 2℃ / second. The rate threshold is set based on the following: This threshold can be determined through statistical analysis of historical fault data, or calibrated through experiments simulating temperature rise rates under different degrees of loosening. In this embodiment, 2℃ / second is taken as a typical value, based on experimental statistical results of temperature rise characteristics during the accelerated increase of contact resistance at connection points. This effectively captures abnormal trends in the early deterioration stage while avoiding false alarms caused by fluctuations in normal operating conditions. In practical applications, it can be adjusted according to the system response speed and false alarm tolerance.

[0037] The comprehensive judgment logic is as follows: Condition A (Static Exceedance): If ΔT_max > ΔT_static_th, then immediately determine that there is a serious connection anomaly in the phase with the highest temperature, Ph_max, generate a "serious connection fault" fault code, and report it through the CAN bus; Condition B (Dynamic Exceeding Limit): If ΔT_max > ΔT_dyn_th and the duration exceeds the first preset time (set to 30 seconds in this embodiment), it is determined that the phase with the highest temperature, Ph_max, has an early degradation risk in the connection state, and a "early degradation warning of connection state" fault code is generated. Condition C (Abnormal Trend): If dΔT / dt > rate threshold (2℃ / second) and the duration exceeds the second preset time (set to 10 seconds in this embodiment), it indicates that the contact resistance is rapidly deteriorating. Even if the current ΔT_max has not yet exceeded the dynamic threshold, a "rapid deterioration warning of connection status" fault code will be generated immediately. The first and second preset times are set based on the following: The first preset time (30 seconds) is used to filter out interference caused by instantaneous current surges or sampling noise, ensuring the reliability of dynamic threshold over-limit judgment. Its value is based on statistical analysis of the typical thermal time constant of the motor and load fluctuation characteristics. The second preset time (10 seconds) is used to capture continuous rapid deterioration trends and avoid false alarms caused by single fluctuations. Its value is based on experimental observation results of the early fault evolution speed of the connection point. In specific applications, these two time parameters can be adaptively adjusted according to the system time constant, sampling frequency and false alarm rate requirements.

[0038] When any one of conditions A, B, or C is met, the diagnostic output unit sends the corresponding warning signal to the vehicle controller via the CAN bus for instrument display, log recording, and adjustment of the vehicle energy management strategy.

[0039] Step S106: Sensor self-diagnosis To ensure the reliability of the monitoring system itself, this embodiment also includes a sensor self-diagnosis step; the main control unit monitors in real time whether the sampled values ​​V_u, V_v, and V_w of each ADC are within the preset effective physical range; the voltage range corresponding to the PT1000 in the temperature measurement range of -40℃ to 200℃ is approximately 0.96V to 1.78V (under 1mA excitation); if the sampled value of a certain channel is close to 0V (less than 0.1V), it is determined to be a short circuit fault; if the sampled value is close to the ADC reference voltage (e.g., 3.3V) or exceeds the upper limit (greater than 2.0V), it is determined to be an open circuit fault; once a fault is detected, the corresponding sensor fault code is immediately generated and reported.

[0040] Example 3: Optionally, this embodiment provides a specific structure for a three-phase terminal temperature monitoring system for heavy-duty truck motors used to implement the method of Embodiment 2. The system consists of three main parts: an integrated sensor module, a signal transmission harness, and a centralized signal processing and control module.

[0041] Integrated sensor module: The integrated sensor module includes three temperature sensing units, which are respectively set on the U-phase, V-phase, and W-phase output terminal blocks 101 of the heavy truck motor. In this embodiment, the temperature sensing unit adopts an insulated encapsulated PT1000 thin film platinum resistance thermometer 103, which has the characteristics of high temperature resistance, high precision, and good long-term stability. The output terminal block 101 has mounting windows on its housing corresponding to the positions of the conductive components 102 for each phase. The conductive components 102 can be nut inserts or built-in copper busbars. During installation, a PT1000 thin-film platinum resistance thermometer 103 is inserted into the window, ensuring that its temperature-sensing surface is in close contact with the surface of the conductive component 102 to achieve good thermal coupling. Subsequently, a high-temperature resistant, high-thermal-conductivity epoxy resin potting compound 104 with good insulation properties is used to fill the remaining space of the window and completely cover the sensor body and the root of the lead wire. After the potting compound cures, it forms an integrated sealing structure, simultaneously achieving the following functions: Mechanical fixing: to prevent the sensor from shifting or falling off under severe vibration; Enhanced thermal conductivity: Fills tiny gaps to reduce contact thermal resistance; Electrical insulation: Ensure high-voltage insulation between the sensor and conductive component 102; Environmental protection: Sealed against moisture, oil, and corrosion; The lead wire of the temperature sensing unit is connected to the signal transmission cable 105 and led out to the centralized signal processing and control module.

[0042] Signal transmission harness: The signal transmission harness uses a four-core shielded twisted pair cable, including three signal lines (S_U, S_V, S_W) and one common ground line (GND_COM). The three signal lines are connected to the temperature sensing units of the U, V, and W phases respectively, and the common ground line is connected to the system signal reference ground. The shielding layer of the shielded twisted pair cable is grounded at a single point at the interface of the centralized signal processing and control module to effectively suppress electromagnetic interference and ensure reliable transmission of weak temperature signals in strong electromagnetic environments.

[0043] Centralized signal processing and control module: The centralized signal processing and control module is located inside the motor controller housing and mainly includes the following units: Signal input protection circuit: Composed of transient voltage suppressor diodes (TVS) and RC filter circuit, it is used to suppress surges and electromagnetic interference from the wiring harness and protect the precision circuits at the back end; Multiple precision constant current sources: Three independent 1mA constant current sources are formed by a precision voltage reference source and an operational amplifier, which provide excitation current for the PT1000 sensing units of the U, V and W phases respectively; each constant current source is independent of each other to avoid crosstalk between channels; Multi-channel synchronous sampling analog-to-digital converter (ADC): This embodiment uses the AD7124-8 chip from ADI, which supports 8-channel differential input, has a built-in programmable gain amplifier, and has synchronous sampling function; the voltage signals of the three sensing units are connected to the three channels of the ADC and configured in synchronous sampling mode to ensure that the three-phase voltage signals are acquired at the same time, eliminating the sampling time error caused by current transients; Main control unit (MCU): It adopts Infineon TC275 automotive-grade microcontroller, which communicates with ADC through SPI interface to read sampled data; it communicates with the vehicle network through CAN interface to obtain the real-time motor current and report the diagnostic results; the MCU integrates a storage unit to store preset multi-level absolute temperature thresholds, static temperature difference threshold ΔT_static_th, rate threshold, and lookup table or fitting coefficients of current-temperature difference baseline model ΔT_base(I); The arithmetic unit, as a software functional module of the MCU, is configured to execute steps S103 to S105 of Embodiment 2, including: The dynamic temperature difference threshold ΔT_dyn_th is generated based on the real-time current I_rms and the current-temperature difference baseline model. Calculate the maximum temperature difference ΔT_max between the three phases; Calculate the rate of change dΔT / dt of ΔT_max within a 10-second window; Compare ΔT_max with the static threshold ΔT_static_th and the dynamic threshold ΔT_dyn_th, and compare dΔT / dt with the rate threshold. Make a comprehensive logical judgment based on the comparison results.

[0044] Diagnostic output unit: Also a software function module of the MCU, it generates corresponding fault codes and warning signals based on the judgment results of the calculation unit, and sends them to the vehicle controller via the CAN bus.

[0045] Example 4: Optionally, to further illustrate the method for generating the dynamic temperature difference threshold in step S103, in this embodiment, the current-temperature difference baseline model obtained through bench testing is assumed to be: ΔT_base(I) = 0.00018·I 2 +1.8 Where I is the effective value of the motor operating current, in A; ΔT_base is in °C; the reliability coefficient α is taken as 1.3, then the dynamic temperature difference threshold is: ΔT_dyn_th = 1.3 × (0.00018·I 2 + 1.8) For example, when the motor operates at a rated current of 500A, ΔT_base = 0.00018×250000 + 1.8 = 45 + 1.8 = 46.8℃, ΔT_dyn_th = 1.3×46.8 ≈ 60.8℃; when the motor operates at a low current of 100A, ΔT_base = 0.00018×10000 + 1.8 = 1.8 + 1.8 = 3.6℃, ​​ΔT_dyn_th = 1.3×3.6 ≈ 4.7℃. It can be seen that the dynamic threshold adaptively adjusts with changes in current, effectively avoiding missed alarms caused by an excessively high fixed threshold at low currents and false alarms caused by an excessively low fixed threshold at high currents.

[0046] The calibration process for the above current-temperature difference baseline model ΔT_base(I) is as follows: First, select the motor under test and its three-phase terminal assembly with good connection status, and install it in the test bench environment to ensure that the connection points of each phase are reliable and free of initial defects. Secondly, by means of the motor controller or external power supply, a number of stable load currents Ii of different levels are applied to the motor. In this embodiment, 20%, 40%, 60%, 80%, and 100% of the rated current are selected as the calibration operating points, i.e., Ii = 100A, 200A, 300A, 400A, and 500A (taking 500A as an example). Next, under each rated current Ii, continue running until the system reaches thermal equilibrium (the criterion is that the temperature of each phase does not change by more than ±0.5℃ within 10 minutes). Record the stable temperature values ​​T_u_i, T_v_i, and T_w_i of the three phases U, V, and W at this time, and calculate the maximum temperature difference of the three phases ΔT_base_i = max(T_u_i, T_v_i, T_w_i) - min(T_u_i, T_v_i, T_w_i) under this current. Then, curve fitting was performed on multiple sets of calibration data points (Ii, ΔT_base_i). Based on thermodynamic principles, the temperature rise of the connection point under normal operating conditions is proportional to the square of the current. Therefore, a quadratic polynomial model ΔT_base(I) = k·I was adopted. 2 The least squares fit is performed with c to obtain the specific values ​​of the empirical coefficients k and c (for example, in this embodiment, k=0.00018, c=1.8). Finally, the fitted function expression or the corresponding lookup table is stored in the controller storage unit as a benchmark model for calculating the dynamic temperature difference threshold.

[0047] The calibration process can be completed in one go when the motor product is finalized. Motors of the same model can use the same calibration parameters, without the need for individual calibration of each motor.

[0048] Example 5: Optionally, this embodiment illustrates the working timing of the multi-dimensional diagnostic logic through a typical fault evolution process; suppose that the three-phase connection of a heavy truck motor is normal at time t0 and the three-phase temperature is balanced; subsequently, the U-phase connection point gradually loosens due to vibration, and the contact resistance begins to increase slowly.

[0049] At time t1 (trend anomaly warning): the temperature of phase U begins to rise at a relatively rapid rate, and ΔT_max gradually increases; at time t1, dΔT / dt exceeds 2℃ / second and lasts for 10 seconds, at which point ΔT_max is 15℃, which has not yet exceeded the dynamic threshold (assuming the current current corresponds to a dynamic threshold of 25℃); the system determines that condition C is met and generates a "rapid deterioration warning of connection status", prompting maintenance personnel to check the connection point of phase U; At time t2 (early degradation warning): As the contact resistance of phase U increases further, ΔT_max continues to rise to 28℃, exceeding the current dynamic threshold of 25℃, and remains there for 30 seconds; at this time, condition B is met, and the system upgrade warning is "early degradation warning of connection status". It is recommended to arrange maintenance as soon as possible. At time t3 (serious fault alarm): If not handled in time, the temperature of phase U continues to rise, and ΔT_max reaches 26℃, exceeding the static threshold of 25℃, which meets condition A. The system will immediately issue a "serious connection fault" alarm and may trigger derating or shutdown protection.

[0050] As can be seen from the above timing sequence, the multi-dimensional diagnostic logic of the present invention can provide differentiated early warning information at different stages of fault development, achieving complete coverage from fault prediction to fault alarm.

[0051] Example 6 Optionally, this embodiment details the implementation of the sensor self-diagnostic steps; the MCU reads the sampled values ​​of each ADC in real time and compares them with preset upper and lower threshold values; settings: Short circuit threshold: V_short = 0.1V (corresponding to a PT1000 resistor of approximately 100Ω, far below the normal range); Open circuit threshold: V_open = 2.0V (corresponding to a PT1000 resistor of approximately 2000Ω, far exceeding the normal range); Normal range: 0.96V~1.78V (corresponding to -40℃~200℃).

[0052] If the sampled value of a certain channel is less than V_short and the duration exceeds 1 second, the channel is determined to be short-circuited and a "U-phase sensor short circuit" (or other corresponding phase) fault code is reported. If the sampled value of a certain channel is greater than V_open and the duration exceeds 1 second, the channel is determined to be open circuit fault, and the "U-phase sensor open circuit" fault code is reported. If the sampled value is within the normal range, continue with the normal temperature calculation.

[0053] This self-diagnostic function ensures that the system can detect sensor or circuit faults in a timely manner, avoid making misjudgments based on erroneous data, and improve the reliability and security of the system.

[0054] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for fault early warning by monitoring the temperature of three-phase terminals of a heavy-duty truck motor, characterized in that: Includes the following steps: S1: Real-time acquisition of temperature signals from the U-phase, V-phase, and W-phase output terminals of the heavy-duty truck motor, and conversion of the temperature signals into three-phase real-time temperature values ​​T_u, T_v, and T_w, while simultaneously acquiring the current operating current value I of the motor; S2: Based on preset multi-level absolute temperature thresholds, graded protection judgment is performed on the real-time temperature values ​​of the three phases; S3: Based on the current operating current value I, generate a dynamic temperature difference threshold ΔT_dyn_th corresponding to the operating current value; S4: Based on the real-time three-phase temperature values ​​T_u, T_v, and T_w, calculate the real-time temperature difference characteristic value ΔT between the three phases, and calculate the rate of change dΔT / dt of the real-time temperature difference characteristic value ΔT within a preset time window; S5: Compare the real-time temperature difference characteristic value ΔT with the preset static temperature difference threshold ΔT_static_th and the dynamic temperature difference threshold ΔT_dyn_th, and compare the rate of change dΔT / dt with the preset rate threshold. Based on the comparison results, comprehensively determine whether there is a phase with abnormal connection status, and generate a corresponding warning signal.

2. The method for fault early warning of three-phase terminal temperature monitoring of heavy-duty truck motors according to claim 1, characterized in that: The method for generating the dynamic temperature difference threshold ΔT_dyn_th in step S3 is as follows: Based on the pre-calibrated current-temperature difference baseline model ΔT_base(I), the reference temperature difference value ΔT_base under the current operating current value I is calculated. The dynamic temperature difference threshold ΔT_dyn_th = α·ΔT_base, where α is a reliability coefficient greater than 1, and its specific value is pre-calibrated according to the system safety margin requirements.

3. The method for monitoring and warning of faults in the three-phase terminals of a heavy-duty truck motor according to claim 1, characterized in that: The comprehensive judgment method in step S5 includes: Condition A: If the real-time temperature difference characteristic value ΔT is greater than the static temperature difference threshold ΔT_static_th, then it is determined that the phase with the highest temperature corresponding to the real-time temperature difference characteristic value ΔT has a serious connection anomaly. Condition B: If the real-time temperature difference characteristic value ΔT is greater than the dynamic temperature difference threshold ΔT_dyn_th and the duration exceeds the first preset time, it is determined that the phase with the highest temperature has an early risk of connection state degradation. Condition C: If the rate of change dΔT / dt is greater than the preset rate threshold and the duration exceeds the second preset time, then the connection status is determined to be rapidly deteriorating; When any one of condition A, condition B, or condition C is met, a corresponding warning signal is generated.

4. The method for fault early warning of three-phase terminal temperature monitoring of heavy-duty truck motors according to claim 1, characterized in that: The real-time temperature difference characteristic value ΔT is the difference between the maximum and minimum values ​​of the three-phase temperatures, i.e., ΔT = max(T_u, T_v, T_w) - min(T_u, T_v, T_w).

5. The method for fault early warning of three-phase terminal temperature monitoring of heavy-duty truck motors according to claim 1, characterized in that: In step S1, the temperature signals of the U-phase, V-phase, and W-phase output terminals are acquired simultaneously through synchronous sampling.

6. The method for fault early warning of three-phase terminal temperature monitoring of heavy-duty truck motors according to claim 1, characterized in that: It also includes sensor self-diagnostic steps: Determine whether the voltage value of each temperature signal is within the preset effective physical range. If it exceeds the effective physical range, determine that the corresponding temperature sensing unit or transmission line has an open circuit or short circuit fault.

7. A three-phase terminal temperature monitoring system for heavy-duty truck motors, used to implement the method described in any one of claims 1-6, characterized in that: include: An integrated sensor module includes three temperature sensing units, which are respectively disposed on the U-phase, V-phase, and W-phase output terminal blocks of the heavy truck motor. Each temperature sensing unit is thermally coupled to the conductive component of its corresponding output terminal block to sense the temperature of the conductive component and generate a temperature signal. A signal transmission harness is connected to the integrated sensor module for transmitting the temperature signal; A centralized signal processing and control module, connected to the signal transmission harness, is arranged inside the motor controller housing. The centralized signal processing and control module includes: The current acquisition unit is used to acquire the current operating current value I of the motor. The signal acquisition unit is used to receive and process the temperature signal, and convert it into three-phase real-time temperature values ​​T_u, T_v, and T_w. The storage unit is used to store the preset multi-level absolute temperature threshold, static temperature difference threshold ΔT_static_th, rate threshold, and current-temperature difference baseline model ΔT_base(I); The arithmetic unit is connected to the current acquisition unit, the signal acquisition unit, and the storage unit, respectively, and is configured to perform the following operations: Based on the current operating current value I and the current-temperature difference baseline model ΔT_base(I), a dynamic temperature difference threshold ΔT_dyn_th is generated; Calculate the real-time temperature difference characteristic value ΔT between the three phase temperatures; Calculate the rate of change dΔT / dt of the real-time temperature difference characteristic value ΔT within a preset time window; The real-time temperature difference characteristic value ΔT is compared with the static temperature difference threshold ΔT_static_th and the dynamic temperature difference threshold ΔT_dyn_th, and the rate of change dΔT / dt is compared with the rate threshold. A diagnostic output unit, connected to the arithmetic unit, is used to generate and output a corresponding warning signal based on the comparison result.

8. The three-phase terminal temperature monitoring system for heavy-duty truck motors according to claim 7, characterized in that: The output terminal block includes a housing, on which mounting windows are provided corresponding to the positions of each phase conductive component. The temperature sensing unit is embedded in the mounting window, and the temperature sensing surface of the temperature sensing unit is in contact with the surface of the conductive component. The mounting window is filled with potting compound, which covers the temperature sensing unit and the root of its lead.

9. The three-phase terminal temperature monitoring system for heavy-duty truck motors according to claim 7, characterized in that: The signal transmission harness is a shielded twisted pair cable, including three signal lines and one conductor as a common reference ground. The three signal lines are connected to three temperature sensing units respectively. The common ground and the grounding terminals of the three temperature sensing units are connected to the system signal reference ground. The shielding layer of the shielded twisted pair cable is grounded at a single point at the interface of the centralized signal processing and control module.

10. The three-phase terminal temperature monitoring system for heavy-duty truck motors according to claim 7, characterized in that: The signal acquisition unit includes: A multi-channel precision constant current source is used to provide independent excitation current for the three temperature sensing units; A multi-channel synchronous sampling analog-to-digital converter is used to synchronously acquire the voltage signals generated by the three temperature sensing units in response to the excitation current.

Images