Enameled wire testing method and device based on heat engine stress

Abstract

The invention discloses an enamelled wire testing method and device based on heat engine stress, and belongs to the technical field of enamelled wire testing, and the method comprises the steps: S1, extracting a thermal tolerance range based on the historical operation data change characteristics of an enamelled wire; s2, adjusting the real-time temperature and the real-time mechanical stress of the enameled wire according to the thermal tolerance range and the automatic control principle; s3, after the real-time temperature of the enameled wire and the real-time mechanical stress of the enameled wire are adjusted, the real-time voltage of the enameled wire is controlled based on a boost rule for testing, and test data are recorded; s4, detecting the real-time state of the enameled wire, and when the real-time state is a failure state, ending the test; synchronously, when the real-time voltage of the enameled wire is greater than or equal to the cut-off voltage corresponding to the boost rule, ending the test; s5, generating an enamelled wire performance report based on the voltage corresponding to the enamelled wire failure state and the test data; the problem that complex working conditions are difficult to simulate to accurately test the real performance of the enameled wire due to the fact that relative static control of multiple test data is not considered in the prior art is solved.

Description

Technical Field

[0001] The invention relates to the technical field of enameled wire testing, and in particular to an enameled wire testing method and device based on thermomechanical stress. Background Art

[0002] Enameled wire often performs the dual functions of conductivity and insulation in electrical equipment such as motors and transformers. It faces complex environmental influences such as high temperature, vibration, and stress during operation. Factors such as high temperature, vibration, and stress can deteriorate the mechanical and electrical properties of the enameled wire, thereby reducing the safety of corresponding electrical equipment such as motors and transformers, and shortening the service life of the corresponding electrical equipment. Therefore, it is necessary to accurately test the mechanical and electrical properties of the enameled wire so that electrical equipment can be maintained based on the test results.

[0003] At present, there are some testing equipment on the market that can evaluate the electrical properties or mechanical properties of enameled wires respectively. For example, insulation resistance testers, high-voltage withstand voltage testers and other equipment can evaluate the electrical strength and leakage current of enameled wires. Tensile testing machines, fatigue testers and other equipment can apply mechanical stress to evaluate the tensile strength and fracture performance of enameled wires. However, these devices can only evaluate the corresponding performance of enameled wires in a single physical environment, that is, they cannot test the mechanical and electrical properties of enameled wires at the same time, and cannot fully reflect the true performance of enameled wires under complex working conditions.

[0004] Chinese patent, publication number: CN118195427B, publication date: August 6, 2024, discloses a comprehensive detection system for cable production, including: basic analysis module, performance detection module, usage detection module and summary evaluation module: basic analysis module, obtains the appearance data of N cables produced in the same batch from the database, and analyzes and processes the appearance data, and compares the analysis and processing results with the set appearance grade interval to perform cable appearance rating; its technical points are: starting from the basic data, performance data and usage data of the cable, each data is rated separately, and then the rating data is processed and scored; however, the invention does not consider relatively static control of multiple data ratings, which makes it difficult to simulate complex physical environments to test the true performance of cables. Summary of the invention

[0005] The purpose of the present invention is to address the problem that the prior art does not consider the relative static control of multiple test data, resulting in difficulty in simulating complex working conditions to accurately test the true performance of enameled wires; a method and device for testing enameled wires based on thermomechanical stress are proposed, and the change characteristics of multiple data when the enameled wires are running under complex working conditions, that is, the thermal tolerance range, are obtained through the historical operation data of the enameled wires, and the temperature and mechanical stress of the enameled wires are adjusted based on the thermal tolerance range. Under the premise that the temperature and mechanical stress of the enameled wires remain unchanged, the voltage of the enameled wires is adjusted for testing, and the test data of the enameled wires when the relative changes of the voltage, temperature and mechanical stress meet the actual complex working conditions are obtained and a corresponding enameled wire performance report is generated, which significantly improves the accuracy of the enameled wire performance test.

[0006] In a first aspect, a technical solution provided in an embodiment of the present invention is a method for testing an enameled wire based on thermomechanical stress, comprising the following steps: S1. Acquire historical operation data of the enameled wire, and extract a thermal tolerance range based on the change characteristics of the historical operation data of the enameled wire; S2. adjusting the real-time temperature and the real-time mechanical stress of the enameled wire according to the thermal tolerance range and the automatic control principle; S3, when the real-time temperature and the real-time mechanical stress of the enameled wire are adjusted, the real-time voltage of the enameled wire is controlled based on the voltage boost rule to perform a test and record the test data; S4, detecting the real-time state of the enameled wire, and ending the test when the real-time state is a failure state; Synchronously, when the real-time voltage of the enameled wire is greater than or equal to the cut-off voltage corresponding to the boost rule, the test is terminated; S5. Generate an enameled wire performance report based on the voltage corresponding to the enameled wire failure state and the test data.

[0007] In this scheme, the thermal tolerance range is extracted based on the change characteristics of the historical operation data of the enameled wire, and the relative change trends of the corresponding temperature and mechanical stress when the enameled wire is running under actual complex working conditions are clarified. The real-time temperature and real-time mechanical stress of the enameled wire are adjusted based on the thermal tolerance range combined with the automatic control principle to simulate the actual complex working conditions, so that the changes of the enameled wire are consistent with the changes during actual work, and the ideal change of a certain factor is prevented from causing the test results to be inconsistent with the actual ones. Then, the real-time voltage of the enameled wire is controlled according to the boost rule for testing. With the help of the relative change trend of temperature and mechanical stress, that is, the thermal tolerance range, the relative change trends of voltage, temperature and mechanical stress are consistent with the actual complex working conditions, and an enameled wire performance report is generated based on the test data, which significantly improves the accuracy of the enameled wire performance test.

[0008] Preferably, in S1, the specific process of extracting the thermal tolerance range based on the change characteristics of the historical operation data of the enameled wire is: S11, drawing a temperature change curve according to the temperature data in the historical operation data of the enameled wire, and drawing a stress change curve according to the mechanical stress data in the historical operation data of the enameled wire; S12, fitting the temperature change curve and the stress change curve based on the time change scale of the historical operation data of the enameled wire to obtain a fitting curve; S13. Determine a thermal tolerance range according to the changing trend of the fitting curve and the time changing scale of the fitting curve.

[0009] In this scheme, a temperature change curve is drawn according to the corresponding temperature data of the enameled wire, and a stress change curve is drawn according to the corresponding mechanical stress data of the enameled wire, so that the temperature change characteristics and mechanical stress change characteristics of the enameled wire are visualized. Then, the temperature change curve and the stress change curve are fitted based on the time change scale of the historical operation data of the enameled wire, and the change characteristics of the corresponding relationship between the temperature and mechanical stress of the enameled wire in the same time period and under the same working environment are obtained, thereby determining the thermal tolerance range.

[0010] Preferably, in S2, the mathematical expression for adjusting the real-time temperature of the enameled wire and the real-time mechanical stress of the enameled wire according to the thermal tolerance range and the automatic control principle is: ; ; ; In the formula, is the PID control output at time t, 1 represents temperature, 2 represents mechanical stress, is the PID proportional parameter, is the error between the target value and the actual value of the control variable at time t, is the PID integral parameter, is the PID differential parameter, is the control variable at time t+1, is the control variable at time t, is the adjustment factor, Thermal tolerance range.

[0011] Preferably, in S3, the specific process of controlling the real-time voltage of the enameled wire based on the voltage boost rule is: The theoretical breakdown voltage of the enameled wire is compared with the voltage threshold corresponding to the boost rule. When the real-time voltage of the enameled wire is less than or equal to the first voltage threshold, the real-time voltage of the enameled wire is adjusted based on the first boost rate; when the real-time voltage of the enameled wire is greater than the first voltage threshold and less than or equal to the second voltage threshold, the real-time voltage of the enameled wire is adjusted based on the second boost rate; when the real-time voltage of the enameled wire is greater than the second voltage threshold, the real-time voltage of the enameled wire is adjusted based on the third boost rate.

[0012] In this scheme, the voltage boost rate of the enameled wire during the test is determined according to the theoretical breakdown voltage of the enameled wire and the voltage threshold corresponding to the voltage boost rule, which can prevent the missed detection problem caused by the test voltage not reaching the theoretical breakdown voltage of the enameled wire. The voltage change of the enameled wire during actual operation can be simulated through a suitable voltage boost rate, which truly reflects the electrical performance of the enameled wire, and prevents the safety problems caused by the breakdown of the enameled wire through a suitable voltage boost rate and voltage threshold.

[0013] Preferably, in S3, during the process of testing the real-time voltage of the enameled wire based on the voltage boost rule: It also monitors the real-time temperature of the enameled wire and adjusts the real-time temperature of the enameled wire according to a preset temperature range, thermal tolerance range and automatic control principle; Simultaneously, the real-time mechanical stress of the enameled wire is also monitored, and the real-time mechanical stress of the enameled wire is adjusted according to a preset mechanical stress range, a thermal tolerance range and an automatic control principle.

[0014] In this scheme, since the voltage, temperature, and mechanical stress may affect each other and change during the test, the temperature and mechanical stress of the enameled wire are monitored and adjusted in real time during the test process to ensure that the relative change trends of the voltage, temperature, and mechanical stress during the test remain unchanged.

[0015] Preferably, in S5, the specific process of generating the enameled wire performance report based on the voltage corresponding to the enameled wire failure state and the test data is as follows: S51, if the enameled wire fails, the voltage corresponding to the failure state of the enameled wire is marked as the breakdown voltage; if the enameled wire does not fail, the cut-off voltage corresponding to the end of the test of the enameled wire is marked as the breakdown voltage; S52, performing comparative analysis based on the breakdown voltage and the test data to obtain changes in electrical properties and mechanical properties of the enameled wire; S53, sorting out the changes in the electrical properties and mechanical properties of the enameled wire to obtain a performance report of the enameled wire.

[0016] On the other hand, a technical solution also provided in an embodiment of the present invention is a thermomechanical stress-based enameled wire testing device, comprising: a temperature control module, a mechanical stress loading module, a synchronous control module, a closed cavity and a testing module; The control end of the temperature control module is electrically connected to the first controlled end of the sealed cavity, the temperature collection end of the temperature control module is electrically connected to the temperature collection end of the sealed cavity, the controlled end of the temperature control module is electrically connected to the first control end of the synchronous control module, the control end of the mechanical stress loading module is connected to the second controlled end of the sealed cavity, the controlled end of the mechanical stress loading module is electrically connected to the second control end of the synchronous control module, the temperature collection end of the synchronous control module is electrically connected to the temperature collection end of the sealed cavity, the stress collection end of the synchronous control module is connected to the stress collection end of the sealed cavity, and the test output end of the test module is electrically connected to the test input end of the sealed cavity.

[0017] In this solution, the test environment of the enameled wire is isolated from the outside world by a closed cavity, thereby ensuring that the test environment of the enameled wire can be highly consistent with the actual working environment, preventing external non-test factors from affecting the test results.

[0018] Furthermore, the enclosed cavity includes: a cavity, a high-pressure observation window, an oil filling and discharge port, a cable lead-out hole, and a heating pipeline; A high-pressure observation window is provided on the top of the cavity, a cable lead-out hole is provided on one side of the high-pressure observation window, an oil filling and discharge port is provided on the side of the cavity, a heating pipeline is provided on one side of the oil filling and discharge port, the input end of the heating pipeline is electrically connected to the control end of the temperature control module as the first controlled end of the closed cavity, the output end of the heating pipeline is electrically connected to the temperature collection end of the temperature control module and the temperature collection end of the synchronous control module as the temperature collection end of the closed cavity, a mechanical stress point is provided inside the cavity as the second controlled end of the closed cavity, connected to the control end of the mechanical stress loading module, and the mechanical stress point is also connected to the stress collection end of the synchronous control module as the stress collection end of the closed cavity, and the cable lead-out hole is electrically connected to the test output end of the test module as the test input end of the closed cavity.

[0019] In this solution, the changes in the enameled wire test process can be observed in real time through the high-voltage observation window, and the test results can be corrected using images or manually. In addition, the oil filling and discharge ports cooperate with the cable lead-out holes to convert the medium in the cavity, such as air, transformer oil, etc., under the premise that the closed cavity is completely closed, while ensuring that the process of the enameled wire entering and exiting the cavity is not affected.

[0020] Furthermore, the mechanical stress loading module includes: a servo motor, a stress loading component, and a sample fixing bracket; The sample fixing bracket is used to fix the position of the enameled wire in the closed cavity during testing; The servo motor applies mechanical stress to the enameled wire through a stress loading assembly; The force-applying end of the stress loading component is connected to the second controlled end of the closed cavity as the control end of the mechanical stress loading module, and the controlled end of the servo motor is electrically connected to the second control end of the synchronous control module as the controlled end of the mechanical stress loading module.

[0021] Further, the test module includes: a transformer, a current limiting resistor, a resistor-capacitor voltage divider, a ball gap protection resistor, a ball gap, and a test terminal; The positive terminal of the transformer is electrically connected to the first end of the current limiting resistor, the second end of the current limiting resistor is electrically connected to the first end of the resistor-capacitor voltage divider, the second end of the resistor-capacitor voltage divider is electrically connected to the negative terminal of the transformer, the second end of the current limiting resistor is electrically connected to the first end of the ball gap protection resistor, the second end of the ball gap protection resistor is electrically connected to the input end of the ball gap, the output end of the ball gap is electrically connected to the negative terminal of the transformer, the second end of the current limiting resistor is electrically connected to the positive pole of the test end, the negative pole of the test end is electrically connected to the negative terminal of the transformer, and the test end is electrically connected to the test input end of the sealed cavity as the test output end of the test module.

[0022] The present invention has at least the following substantial effects: The present application extracts the thermal tolerance range based on the change characteristics of the historical operation data of the enameled wire, clarifies the relative change trends of the corresponding temperature and mechanical stress when the enameled wire is running under actual complex working conditions, adjusts the real-time temperature and real-time mechanical stress of the enameled wire based on the thermal tolerance range in combination with the automatic control principle, simulates the actual complex working conditions, and makes the changes of the enameled wire match the changes during actual work, preventing the ideal change of a certain factor from causing the test results to be inconsistent with the actual conditions, and then controls the real-time voltage of the enameled wire according to the boost rule for testing, and uses the relative change trends of temperature and mechanical stress, that is, the thermal tolerance range, to make the relative change trends of voltage, temperature and mechanical stress match the actual complex working conditions, and at the same time, monitors and adjusts the temperature and mechanical stress of the enameled wire in real time during the test to ensure that the relative change trends of voltage, temperature and mechanical stress during the test remain unchanged, and finally generates an enameled wire performance report based on the test data, significantly improving the accuracy of the enameled wire performance test. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings. The drawings are only for the purpose of illustrating preferred embodiments and are not to be considered as limiting the present invention. Also, the same reference symbols are used throughout the drawings to represent the same parts.

[0024] Figure 1 This is a flow chart of an enameled wire testing method based on thermomechanical stress of the present invention; Figure 2It is a schematic diagram of the results of an enameled wire testing device based on thermomechanical stress; Figure 3 A top view of the closed cavity. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation method described herein is only an optimal embodiment of the present invention, which is only used to explain the present invention and does not limit the scope of protection of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe the operations (or steps) as sequential processes, many of the operations (or steps) therein can be implemented in parallel, concurrently, or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but can also have additional steps not included in the drawings; the process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0027] Embodiment 1: like Figure 1 As shown, this embodiment provides an enameled wire testing method based on thermomechanical stress, comprising the following steps: S1. Acquire historical operation data of the enameled wire, and extract a thermal tolerance range based on the change characteristics of the historical operation data of the enameled wire; S11, drawing a temperature change curve according to the temperature data in the historical operation data of the enameled wire, and drawing a stress change curve according to the mechanical stress data in the historical operation data of the enameled wire; S12, fitting the temperature change curve and the stress change curve based on the time change scale of the historical operation data of the enameled wire to obtain a fitting curve; S13. Determine a thermal tolerance range according to the changing trend of the fitting curve and the time changing scale of the fitting curve.

[0028] In this embodiment, during the working process of the enameled wire, the temperature and mechanical stress of the enameled wire change with time and various factors, and there is a certain connection between them. The voltage of the enameled wire is related to the corresponding transmission line, etc., and usually will not change significantly. Therefore, the connection between temperature and mechanical stress is extracted as the thermal tolerance range to participate in the control process of temperature, mechanical stress and voltage during the enameled wire testing process, so as to support the simulation of the complex working conditions of the actual working of the enameled wire.

[0029] S2. adjusting the real-time temperature and the real-time mechanical stress of the enameled wire according to the thermal tolerance range and the automatic control principle; In one embodiment, the mathematical expression for adjusting the real-time temperature of the enameled wire and the real-time mechanical stress of the enameled wire according to the thermal tolerance range and the automatic control principle is: ; ; ; In the formula, is the PID control output at time t, 1 represents temperature, 2 represents mechanical stress, is the PID proportional parameter, is the error between the target value and the actual value of the control variable at time t, is the PID integral parameter, is the PID differential parameter, is the control variable at time t+1, is the control variable at time t, is the adjustment factor, Thermal tolerance range.

[0030] S3. After the real-time temperature and the real-time mechanical stress of the enameled wire are adjusted, the real-time voltage of the enameled wire is controlled based on a voltage boost rule to perform a test and record the test data.

[0031] In one embodiment, the specific process of controlling the real-time voltage of the enameled wire based on the boost rule is: The theoretical breakdown voltage of the enameled wire is compared with the voltage threshold corresponding to the boost rule. When the real-time voltage of the enameled wire is less than or equal to the first voltage threshold, the real-time voltage of the enameled wire is adjusted based on the first boost rate; when the real-time voltage of the enameled wire is greater than the first voltage threshold and less than or equal to the second voltage threshold, the real-time voltage of the enameled wire is adjusted based on the second boost rate; when the real-time voltage of the enameled wire is greater than the second voltage threshold, the real-time voltage of the enameled wire is adjusted based on the third boost rate.

[0032] In this embodiment, when the theoretical breakdown voltage of the enameled wire is less than or equal to 500V, the boost rate is determined to be 20V / s; when the theoretical breakdown voltage of the enameled wire is greater than 500V and the theoretical breakdown voltage of the enameled wire is less than or equal to 2500V, the boost rate is determined to be 100V / s; when the theoretical breakdown voltage of the enameled wire is greater than 2500V, the boost rate is determined to be 500V / s.

[0033] In one embodiment, during the process of controlling the real-time voltage of the enameled wire based on the voltage boost rule for testing: It also monitors the real-time temperature of the enameled wire and adjusts the real-time temperature of the enameled wire according to a preset temperature range, thermal tolerance range and automatic control principle; Simultaneously, the real-time mechanical stress of the enameled wire is also monitored, and the real-time mechanical stress of the enameled wire is adjusted according to a preset mechanical stress range, a thermal tolerance range and an automatic control principle.

[0034] In this embodiment, a real-time feedback mechanism is established in each control cycle of the enameled wire test. The real-time monitoring and adjustment of the temperature and mechanical stress of the enameled wire are realized in the real-time feedback mechanism as follows: ; ; In the formula, is the error between the target value and the actual value of the control variable in n control cycles, 1 represents temperature, 2 represents mechanical stress, The target value set for the control variable in n control cycles, is the actual value of the control variable in n control cycles, is the PID control output in n control cycles, is the PID proportional parameter, is the PID integral parameter, is the PID differential parameter, is the error between the target value and the actual value of the control variable in the jth control cycle, is the time of a single control cycle, is the error between the target value and the actual value of the control variable in n-1 control cycles.

[0035] S4, detecting the real-time state of the enameled wire, and ending the test when the real-time state is a failure state; Synchronously, when the real-time voltage of the enameled wire is greater than or equal to the cut-off voltage corresponding to the boost rule, the test is terminated.

[0036] In this embodiment, the failure state of the enameled wire at least includes the enameled wire being broken down and the enameled wire discharging. When any of the three phenomena occurs, the enameled wire being broken down, the enameled wire discharging, or the real-time voltage of the enameled wire being greater than or equal to the cut-off voltage corresponding to the boost rule, the test is terminated immediately.

[0037] S5, generating an enameled wire performance report based on the voltage corresponding to the enameled wire failure state and the test data; S51, if the enameled wire fails, the voltage corresponding to the failure state of the enameled wire is marked as the breakdown voltage; if the enameled wire does not fail, the cut-off voltage corresponding to the end of the test of the enameled wire is marked as the breakdown voltage; S52, performing comparative analysis based on the breakdown voltage and the test data to obtain changes in electrical properties and mechanical properties of the enameled wire; S53, sorting out the changes in the electrical properties and mechanical properties of the enameled wire to obtain a performance report of the enameled wire.

[0038] In this embodiment, the obtained test data are compared and analyzed to compare the performance changes of the enameled wire under different temperature and pressure conditions, analyze the tolerance and performance retention of the enameled wire in an alternating temperature and pressure environment, and perform statistical analysis on the resistance, insulation resistance, dielectric strength and mechanical property data of the enameled wire under different conditions to evaluate the performance of the enameled wire in complex working conditions.

[0039] like Figure 2 As shown, a technical solution also provided in the embodiment of the present invention is an enameled wire testing device based on thermomechanical stress, comprising: a temperature control module, a mechanical stress loading module, a synchronous control module, a closed cavity and a testing module; The control end of the temperature control module is electrically connected to the first controlled end of the sealed cavity, the temperature collection end of the temperature control module is electrically connected to the temperature collection end of the sealed cavity, the controlled end of the temperature control module is electrically connected to the first control end of the synchronous control module, the control end of the mechanical stress loading module is connected to the second controlled end of the sealed cavity, the controlled end of the mechanical stress loading module is electrically connected to the second control end of the synchronous control module, the temperature collection end of the synchronous control module is electrically connected to the temperature collection end of the sealed cavity, the stress collection end of the synchronous control module is connected to the stress collection end of the sealed cavity, and the test output end of the test module is electrically connected to the test input end of the sealed cavity.

[0040] In this embodiment, the temperature control system is responsible for adjusting the temperature in the closed cavity to provide stable temperature conditions for the test. The temperature control system includes a heating component and a temperature sensor. The heating component includes a resistance heating element and a heating pipeline. A PIC ceramic heating plate with a positive temperature coefficient is used as the resistance heating element. The resistance heating element is placed in the oil or air flow path of the closed cavity through the heating pipeline to achieve uniform heating and make the temperature in the closed cavity rise rapidly. The temperature sensor is arranged around the enameled wire sample through a transmission cable to sense the temperature of the adjacent enameled wire in real time and transmit the data to the temperature control module to achieve parameter setting and monitoring. The synchronous control module is the core of the enameled wire testing device, which is used to coordinate the operation of the temperature control module and the mechanical stress loading module to achieve precise synchronization between the modules. The synchronous control module obtains the temperature and mechanical stress of the enameled wire sample in real time through multi-channel data acquisition, and dynamically adjusts each module based on feedback combined with the PID control algorithm to ensure the stability and consistency of the test conditions.

[0041] In one embodiment, Figure 3 As shown, the enclosed cavity includes: a cavity, a high-pressure observation window, an oil filling and discharge port, a cable lead-out hole, and a heating pipeline; A high-pressure observation window is provided on the top of the cavity, a cable lead-out hole is provided on one side of the high-pressure observation window, an oil filling and discharge port is provided on the side of the cavity, a heating pipeline is provided on one side of the oil filling and discharge port, the input end of the heating pipeline is electrically connected to the control end of the temperature control module as the first controlled end of the closed cavity, the output end of the heating pipeline is electrically connected to the temperature collection end of the temperature control module and the temperature collection end of the synchronous control module as the temperature collection end of the closed cavity, a mechanical stress point is provided inside the cavity as the second controlled end of the closed cavity, connected to the control end of the mechanical stress loading module, and the mechanical stress point is also connected to the stress collection end of the synchronous control module as the stress collection end of the closed cavity, and the cable lead-out hole is electrically connected to the test output end of the test module as the test input end of the closed cavity.

[0042] In this embodiment, the closed cavity is a key component in the enameled wire electrical performance test device, which mainly provides a controllable test environment for the enameled wire sample and isolates it from external interference. The structure of the closed cavity is made of stainless steel or aluminum alloy, and has the characteristics of high temperature resistance, high pressure resistance and corrosion resistance. The interior can be filled with transformer oil to ensure good insulation. At the same time, it is equipped with a temperature control system to maintain the set temperature range (-20°C to 250°C) to achieve a simulation test of temperature influence; secondly, an insulating layer is also provided on the cavity wall of the closed cavity, and the insulating layer includes a basic insulating layer and an enhanced insulating layer, wherein the basic insulating layer is composed of epoxy resin to ensure electrical isolation, and the enhanced insulating layer is composed of silicone rubber composite material, which can enhance the pressure resistance and mechanical strength of the closed cavity. Specifically, the insulation performance is enhanced by coating the high-voltage electrode connection part with epoxy resin and heat shrink tube, that is, the cable lead-out hole and the heating pipe, and the insulation performance of the medium is regularly maintained. Before the test, an overall insulation test is required to ensure that the device has no risk of breakdown or leakage under the test voltage.

[0043] In one embodiment, the mechanical stress loading module includes: a servo motor, a stress loading component, and a sample fixing bracket; The sample fixing bracket is used to fix the position of the enameled wire in the closed cavity during testing; The servo motor applies mechanical stress to the enameled wire through a stress loading assembly; The force-applying end of the stress loading component is connected to the second controlled end of the closed cavity as the control end of the mechanical stress loading module, and the controlled end of the servo motor is electrically connected to the second control end of the synchronous control module as the controlled end of the mechanical stress loading module.

[0044] In this embodiment, the servo motor adopts a high-torque, low-inertia servo motor to ensure high responsiveness and precise control capabilities during stress loading, and remotely controls the mechanical stress loading module in real time through a control circuit. After the stress loading component receives the control signal, the stress loading component applies axial tension, compression and other stresses to the enameled wire sample. The tensile stress range is generally 0N to 500N. The mechanical stress is the tension generated by the enameled wire in the transformer winding due to thermal expansion and contraction and during operation, which is used to simulate the tensile strength of the enameled wire under long-term tension. The compressive stress range is generally 0N to 1000N, which is used to simulate the deformation and microcrack risk of the enameled wire insulation layer due to compressive stress; the sample fixing bracket is used to stabilize the enameled wire. Sample, ensure accurate stress transmission during tensile, compressive or bending stress loading to avoid sliding or deformation. The sample fixing bracket is constructed of corrosion-resistant metal and coated with an insulating layer to prevent short circuit or leakage current during electrical testing. Specifically, the sample fixing bracket includes an adjustable V-shaped clamp and a guide rail and supports the fixation and precise positioning of samples of multiple sizes to ensure uniform stress application and avoid test deviation. The base of the sample fixing bracket is made of high-rigidity material to provide stable support and ensure the correct stress loading process through precise docking with the transmission mechanism. In addition, the sample fixing bracket should be resistant to high temperature and fatigue, and can withstand a temperature control environment of up to 250°C and long-term stress cycles to ensure the stability and consistency of the test data.

[0045] In one embodiment, the test module includes: a transformer, a current limiting resistor, a resistor-capacitor voltage divider, a ball gap protection resistor, a ball gap, and a test terminal; The positive terminal of the transformer is electrically connected to the first end of the current limiting resistor, the second end of the current limiting resistor is electrically connected to the first end of the resistor-capacitor voltage divider, the second end of the resistor-capacitor voltage divider is electrically connected to the negative terminal of the transformer, the second end of the current limiting resistor is electrically connected to the first end of the ball gap protection resistor, the second end of the ball gap protection resistor is electrically connected to the input end of the ball gap, the output end of the ball gap is electrically connected to the negative terminal of the transformer, the second end of the current limiting resistor is electrically connected to the positive pole of the test end, the negative pole of the test end is electrically connected to the negative terminal of the transformer, and the test end is electrically connected to the test input end of the sealed cavity as the test output end of the test module.

[0046] In this embodiment, the transformer should meet the following conditions: the rated power of the transformer is at least 500VA, and it can output an AC voltage with a nearly sinusoidal waveform under test conditions, with a peak factor of √2×(1±5%) (1.34~1.48), and the capacity of the transformer can ensure that the maximum voltage drop when outputting 5mA current is 2%; in this embodiment, a YDJ (G) 1.5 / 50 light AC test transformer with a rated capacity of 1.5KVA and a rated high voltage voltage of 50KV is specifically used.

[0047] In summary, when the test module cooperates with other modules to perform the enameled wire test method based on thermomechanical stress to perform performance test on the enameled wire sample, the test voltage is applied from 0, and the test voltage uses an alternating voltage with a nominal frequency of 50 Hz to perform alternating tests on temperature and stress respectively; The temperature alternating test is specifically as follows: the temperature is set to different values ​​(100°C, 120°C, 140°C, 160°C, 180°C, 200°C), samples with the same parameters are selected, the loading time is 8 hours each time, the pressure value is fixed, and the performance test is performed after the parameters are stabilized each time; The stress alternation test is specifically as follows: setting the pressure to different values ​​(100 N, 200 N, 300 N, 400 N, 500 N), selecting samples with the same parameters, loading for 8 hours each time, fixing the temperature value, and performing performance testing after the parameters are stabilized each time.

[0048] This embodiment has at least the following substantial effects: This embodiment extracts the thermal tolerance range based on the change characteristics of the historical operation data of the enameled wire, clarifies the relative change trends of the corresponding temperature and mechanical stress when the enameled wire is running under actual complex working conditions, adjusts the real-time temperature and real-time mechanical stress of the enameled wire based on the thermal tolerance range in combination with the automatic control principle, simulates the actual complex working conditions, makes the changes of the enameled wire match the changes during actual work, and prevents the ideal change of a certain factor from causing the test results to be inconsistent with the actual conditions, then controls the real-time voltage of the enameled wire according to the boost rule for testing, and uses the relative change trends of temperature and mechanical stress, that is, the thermal tolerance range, to make the relative change trends of voltage, temperature and mechanical stress match the actual complex working conditions, and at the same time, monitors and adjusts the temperature and mechanical stress of the enameled wire in real time during the test to ensure that the relative change trends of voltage, temperature and mechanical stress during the test remain unchanged, and finally generates an enameled wire performance report based on the test data, significantly improving the accuracy of the enameled wire performance test.

[0049] The above specific embodiments are preferred embodiments of the present invention, and are not intended to limit the specific implementation scope of the present invention. The scope of the present invention includes but is not limited to the present specific embodiments. All equivalent changes made in accordance with the shape, structure, and method of the present invention are within the protection scope of the present invention.

Claims

1. A method for testing enameled wire based on thermomechanical stress, characterized in that: The method comprises the following steps: S1. Acquire historical operation data of the enameled wire, and extract a thermal tolerance range based on the change characteristics of the historical operation data of the enameled wire; S2. adjusting the real-time temperature and the real-time mechanical stress of the enameled wire according to the thermal tolerance range and the automatic control principle; S3, when the real-time temperature and the real-time mechanical stress of the enameled wire are adjusted, the real-time voltage of the enameled wire is controlled based on the voltage boost rule to perform a test and record the test data; S4, detecting the real-time state of the enameled wire, and ending the test when the real-time state is a failure state; Synchronously, when the real-time voltage of the enameled wire is greater than or equal to the cut-off voltage corresponding to the boost rule, the test is terminated; S5. Generate an enameled wire performance report based on the voltage corresponding to the enameled wire failure state and the test data.

2. The enameled wire testing method based on thermomechanical stress according to claim 1, characterized in that: In S1, the specific process of extracting the thermal tolerance range based on the change characteristics of the historical operation data of the enameled wire is: S11, drawing a temperature change curve according to the temperature data in the historical operation data of the enameled wire, and drawing a stress change curve according to the mechanical stress data in the historical operation data of the enameled wire; S12, fitting the temperature change curve and the stress change curve based on the time change scale of the historical operation data of the enameled wire to obtain a fitting curve; S13. Determine a thermal tolerance range according to the changing trend of the fitting curve and the time changing scale of the fitting curve.

3. The enameled wire testing method based on thermomechanical stress according to claim 1, characterized in that: In S2, the mathematical expression for adjusting the real-time temperature of the enameled wire and the real-time mechanical stress of the enameled wire according to the thermal tolerance range and the automatic control principle is: ； ； ； In the formula, is the PID control output at time t, 1 represents temperature, 2 represents mechanical stress, is the PID proportional parameter, is the error between the target value and the actual value of the control variable at time t, is the PID integral parameter, is the PID differential parameter, is the control variable at time t+1, is the control variable at time t, is the adjustment factor, Thermal tolerance range.

4. The enameled wire testing method based on thermomechanical stress according to claim 1, characterized in that: In S3, the specific process of controlling the real-time voltage of the enameled wire based on the voltage boost rule is as follows: The theoretical breakdown voltage of the enameled wire is compared with the voltage threshold corresponding to the boost rule. When the real-time voltage of the enameled wire is less than or equal to the first voltage threshold, the real-time voltage of the enameled wire is adjusted based on the first boost rate; when the real-time voltage of the enameled wire is greater than the first voltage threshold and less than or equal to the second voltage threshold, the real-time voltage of the enameled wire is adjusted based on the second boost rate; when the real-time voltage of the enameled wire is greater than the second voltage threshold, the real-time voltage of the enameled wire is adjusted based on the third boost rate.

5. The enameled wire testing method based on thermomechanical stress according to claim 4, characterized in that: In S3, during the test of controlling the real-time voltage of the enameled wire based on the voltage boost rule: It also monitors the real-time temperature of the enameled wire and adjusts the real-time temperature of the enameled wire according to a preset temperature range, thermal tolerance range and automatic control principle; Simultaneously, the real-time mechanical stress of the enameled wire is also monitored, and the real-time mechanical stress of the enameled wire is adjusted according to a preset mechanical stress range, a thermal tolerance range and an automatic control principle.

6. The enameled wire testing method based on thermomechanical stress according to claim 1, characterized in that: In S5, the specific process of generating the enameled wire performance report based on the voltage corresponding to the enameled wire failure state and the test data is as follows: S51, if the enameled wire fails, the voltage corresponding to the failure state of the enameled wire is marked as the breakdown voltage; if the enameled wire does not fail, the cut-off voltage corresponding to the end of the test of the enameled wire is marked as the breakdown voltage; S52, performing comparative analysis based on the breakdown voltage and the test data to obtain changes in electrical properties and mechanical properties of the enameled wire; S53, sorting out the changes in the electrical properties and mechanical properties of the enameled wire to obtain a performance report of the enameled wire.

7. An enameled wire testing device based on thermomechanical stress, applicable to an enameled wire testing method based on thermomechanical stress as claimed in any one of claims 1 to 6, characterized in that: It includes: temperature control module, mechanical stress loading module, synchronous control module, closed cavity and test module; The control end of the temperature control module is electrically connected to the first controlled end of the sealed cavity, the temperature collection end of the temperature control module is electrically connected to the temperature collection end of the sealed cavity, the controlled end of the temperature control module is electrically connected to the first control end of the synchronous control module, the control end of the mechanical stress loading module is connected to the second controlled end of the sealed cavity, the controlled end of the mechanical stress loading module is electrically connected to the second control end of the synchronous control module, the temperature collection end of the synchronous control module is electrically connected to the temperature collection end of the sealed cavity, the stress collection end of the synchronous control module is connected to the stress collection end of the sealed cavity, and the test output end of the test module is electrically connected to the test input end of the sealed cavity.

8. The enameled wire testing device based on thermomechanical stress according to claim 7, characterized in that: The sealed cavity includes: a cavity, a high-pressure observation window, an oil filling and discharge port, a cable lead-out hole, and a heating pipeline; A high-pressure observation window is provided on the top of the cavity, a cable lead-out hole is provided on one side of the high-pressure observation window, an oil filling and discharge port is provided on the side of the cavity, a heating pipeline is provided on one side of the oil filling and discharge port, the input end of the heating pipeline is electrically connected to the control end of the temperature control module as the first controlled end of the closed cavity, the output end of the heating pipeline is electrically connected to the temperature collection end of the temperature control module and the temperature collection end of the synchronous control module as the temperature collection end of the closed cavity, a mechanical stress point is provided inside the cavity as the second controlled end of the closed cavity, connected to the control end of the mechanical stress loading module, and the mechanical stress point is also connected to the stress collection end of the synchronous control module as the stress collection end of the closed cavity, and the cable lead-out hole is electrically connected to the test output end of the test module as the test input end of the closed cavity.

9. The enameled wire testing device based on thermomechanical stress according to claim 7, characterized in that: The mechanical stress loading module includes: a servo motor, a stress loading component, and a sample fixing bracket; The sample fixing bracket is used to fix the position of the enameled wire in the closed cavity during testing; The servo motor applies mechanical stress to the enameled wire through a stress loading assembly; The force-applying end of the stress loading component is connected to the second controlled end of the closed cavity as the control end of the mechanical stress loading module, and the controlled end of the servo motor is electrically connected to the second control end of the synchronous control module as the controlled end of the mechanical stress loading module.

10. The enameled wire testing device based on thermomechanical stress according to claim 7, characterized in that: The test module includes: a transformer, a current limiting resistor, a resistor-capacitor voltage divider, a ball gap protection resistor, a ball gap, and a test terminal; The positive terminal of the transformer is electrically connected to the first end of the current limiting resistor, the second end of the current limiting resistor is electrically connected to the first end of the resistor-capacitor voltage divider, the second end of the resistor-capacitor voltage divider is electrically connected to the negative terminal of the transformer, the second end of the current limiting resistor is electrically connected to the first end of the ball gap protection resistor, the second end of the ball gap protection resistor is electrically connected to the input end of the ball gap, the output end of the ball gap is electrically connected to the negative terminal of the transformer, the second end of the current limiting resistor is electrically connected to the positive pole of the test end, the negative pole of the test end is electrically connected to the negative terminal of the transformer, and the test end is electrically connected to the test input end of the sealed cavity as the test output end of the test module.

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