CN106093130B - Method and system for carrying out thermoelectric combined test on test article coated with electric composite grease - Google Patents

Abstract

The invention relates to a method for conducting a combined thermoelectric test on a sample coated with electric power compound grease, the method comprising: measuring the resistance value of the test object coated with electric power compound grease; place in the combined heat and power test box; adjust the voltage of the input power supply to obtain a regulated test voltage; connect the regulated test voltage to the combined heat and power test box, thereby providing the The power supply to the test object in the combined test chamber; the combined thermoelectric test is performed on the test object coated with the power compound grease under the current working condition; the real-time data of the resistance value of the test object under the current working condition and the temperature rise value are obtained. Real-time data; determine whether the real-time data of the resistance value or temperature rise value of the test object increases linearly; and if the real-time data of the resistance value or temperature rise value does not increase linearly, stop the combined heat and power test.

Description

A method and method for conducting combined thermoelectric test on a sample coated with electrical compound grease system

technical field

The present invention relates to the field of metrology, and more particularly, to a method and a system for performing combined thermoelectric test on a test sample coated with electrical compound grease.

Background technique

Power compound grease is a neutral conductive dressing with good electrical contact performance. Power compound grease is suitable for the contact surface of the lap joint of high and low voltage electrical appliances and various electrical joints, which can significantly reduce the contact resistance and obtain good power-saving economic benefits. Power compound grease is widely used in the contact surface of the busbar and the busbar, the busbar and the equipment terminal connection and the contact surface of the switch contacts in the converter station. The electrical compound grease can be used for the connection of conductors of the same and different metal materials, which replaces and is superior to the tin-lining and silver-plating processes that fasten the contact surface of the connection, which can greatly reduce the contact resistance, thereby reducing the temperature rise.

Power compound grease improves the conductivity of the busbar connection, enhances the safety of power grid operation, saves a lot of power loss, and also avoids galvanic corrosion on the contact surface. Power compound grease is suitable for various environments. It has good high temperature resistance, moisture resistance, oxidation resistance, mildew resistance and chemical corrosion resistance. It also has the characteristics of no flow at high temperature, no cracking at low temperature, stable physical and chemical properties, and long service life. , which greatly improves the safety performance of the conductive paste, and provides a reliable guarantee for the safe operation of the converter station.

The power compound grease at the electrical contact connection of the converter station will gradually age and eventually fail over time, which will cause the temperature of the electrical contact connection to rise, resulting in accidents. In addition, the power compound grease at the electrical contact connection position of the converter station is often in the environment of current flow and temperature change, and its aging is a slow process, which often takes a long time. In order to replace the aging power compound grease at the electrical contact connection in time to avoid such accidents in the converter station, an aging model of the power compound grease at the electrical contact connection of the converter station is established to predict the aging life of the power compound grease in the converter station. Very necessary. In addition, when simulating the aging of the power compound grease, a combined thermoelectric test is usually performed on the sample coated with the power compound grease, and there is no means for performing a combined thermoelectric test in the prior art.

SUMMARY OF THE INVENTION

In order to replace the aged power compound grease at the electrical contact connection in time to avoid accidents caused by the temperature rise at the electrical contact connection of the converter station, this application establishes an accelerated aging model of the power compound grease under the action of thermal-electric coupling to predict the conversion Stream station power compound grease aging life. In addition, in order to determine the parameters in the accelerated aging model, the present application provides a combined thermal and electrical test method for electric power compound grease, and provides a multiple regression method for determining the parameters in the accelerated aging model.

In order to achieve the above goals, the present invention provides a method for conducting a combined thermoelectric test on a test sample coated with an electrical compound grease, the method comprising:

Measure the resistance value of the DUT coated with the power compound grease;

Place the test object coated with the power compound grease in the combined heat and power test box;

Adjust the voltage of the input power supply to obtain a regulated test voltage;

connecting the regulated test voltage to the combined heat and power test box to supply power to the combined heat and power test box and the DUT in the combined heat and power test box;

Under the current working conditions, the combined thermoelectric test is carried out on the DUT coated with the power compound grease;

Obtain the real-time data of the resistance value and the real-time data of the temperature rise value of the test object in the current working condition;

determine whether the real-time data of the resistance value or temperature rise of the DUT is a linear increase; and

If the real-time data of resistance value or temperature rise value does not increase linearly, stop the combined thermoelectric test.

Preferably, if the real-time data of the resistance value or the temperature rise value is a linear increase, the combined thermoelectric test is performed on the test object coated with the power compound grease under the next working condition, until the resistance value or the real-time temperature rise value in the real-time data. When one does not increase linearly, stop the combined thermoelectric test.

Preferably, the internal temperature of the combined heat and power test box is controlled at 20°C to 22°C.

Preferably, the test article is powered according to the temperature rise value of 130Tt/°C, 150Tt/°C, 170Tt/°C or 190Tt/°C.

Preferably, wherein the DUT is powered for 3 hours under each operating condition.

According to another aspect of the present invention, there is provided a system for performing a combined thermoelectric test on a test sample coated with electrical compound grease, the system comprising:

The resistance measuring unit measures the resistance value of the DUT coated with the power compound grease;

Combined thermoelectric test box, used to accommodate the test object coated with electric compound grease;

A voltage adjustment unit, which adjusts the voltage of the input power supply to obtain the adjusted test voltage;

a voltage input unit, connecting the regulated test voltage to the combined heat and power test box, so as to supply power to the combined heat and power test box and the DUT in the combined heat and power test box;

The test unit performs a combined thermoelectric test on the DUT coated with the power compound grease under the current working condition, obtains the real-time data of the resistance value and the real-time data of the temperature rise value of the DUT under the current working condition, and determines the DUT Whether the real-time data of the resistance value or the temperature rise value increases linearly; and if the real-time data of the resistance value or the temperature rise value does not increase linearly, stop the combined heat and power test.

Preferably, if the test unit determines that the real-time data of the resistance value or the temperature rise value is a linear increase, the combined thermoelectric test is performed on the test object coated with the power compound grease under the next working condition, until the real-time data of the resistance value or the temperature rise value. When one of the data does not increase linearly, stop the combined heat and power test.

Preferably, the internal temperature of the combined heat and power test box is controlled at 20°C to 22°C.

Preferably, the test article is powered according to the temperature rise value of 130Tt/°C, 150Tt/°C, 170Tt/°C or 190Tt/°C.

Preferably, wherein the DUT is powered for 3 hours under each operating condition.

Description of drawings

Exemplary embodiments of the present invention may be more fully understood by reference to the following drawings:

1 is a flow chart of establishing an accelerated aging model of electric compound grease according to an embodiment of the present invention;

FIG. 2 is a flowchart of a method for establishing an accelerated aging model of electric compound grease according to another embodiment of the present invention;

3 is a schematic structural diagram of a test circuit according to an embodiment of the present invention;

4 is a flowchart of an accelerated aging test according to an embodiment of the present invention;

FIG. 5 is a flow chart of a method for performing a combined thermoelectric test on a test sample coated with a power compound grease according to another embodiment of the present invention; and.

FIG. 6 is a schematic structural diagram of a system for performing a combined thermoelectric test on a sample coated with an electrical compound grease according to another embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for the purpose of this thorough and complete disclosure invention, and fully convey the scope of the invention to those skilled in the art. The terms used in the exemplary embodiments shown in the drawings are not intended to limit the invention. In the drawings, the same elements/elements are given the same reference numerals.

Unless otherwise defined, terms (including scientific and technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is to be understood that terms defined in commonly used dictionaries should be construed as having meanings consistent with the context in the related art, and should not be construed as idealized or overly formal meanings.

FIG. 1 is a flowchart of a method 100 for establishing an accelerated aging model of an electrical compound grease according to an embodiment of the present invention. The aging of electrical contact connection electrical compound grease is mainly affected by factors such as current, temperature, salt spray, vibration, and ultraviolet light. According to the actual on-site analysis of the electrical contact connection in the line and the converter station, the patent of the present invention believes that the two most important factors affecting the aging performance of the electrical compound grease at the electrical contact connection part are: current and temperature. In addition, when the electrical contact is connected to the operating current and withstands temperature changes, the failure time of the power compound grease is too long, resulting in too long a test period or too little test data. In order to shorten the aging test period of the electric compound grease and obtain a large amount of aging data, the electro-thermal combined accelerated life test of the electric compound grease coated samples in the present application is carried out, and the Weibull distribution test is carried out on the obtained life data, and the parameters are estimated, so as to obtain the Weibull distribution Characteristic lifetime and shape parameters. As shown in FIG. 1 , method 100 begins at step 101 .

Preferably, in step 101, a combined thermoelectric test is performed on the product to be tested coated with the power compound grease under various working conditions by using a test circuit, and the test circuit is obtained under each working condition of the multiple working conditions. The data of resistance value and temperature rise value to determine the linear interval and inflection point value of resistance value or temperature rise value under each operating condition. Preferably, a combined thermoelectric test is performed on the object to be tested coated with the power compound grease under various operating conditions using a test circuit, and the resistance value and temperature of the object to be tested under each operating condition under various operating conditions are obtained. The value-added data, when either the resistance value or the temperature-rise value has an inflection point, the combined thermoelectric test is stopped. Alternatively, when there is no inflection point in both the resistance value and the temperature rise value, increase the current through the DUT until an inflection point occurs in either the resistance value or the temperature rise value, and stop the combined thermoelectric test (described in detail below). Preferably, the object to be tested may be an electrode coated with electrical compound grease.

Preferably, at step 102, it is determined whether the difference between the resistance value or the inflection point value of the temperature rise value under each of the plurality of operating conditions is within a predetermined range. Generally, the resistance value and temperature rise value of the DUT will increase significantly as the power-on time continues. However, the linear ranges of resistance value and temperature rise value increase are different for different DUTs in different environments. Also, when an inflection point occurs, the inflection point value is usually used as the end point of the linear interval.

Preferably, at step 103, if the difference between the resistance value or the inflection point value of the temperature rise value under each of the multiple operating conditions is within a predetermined range and the aging principle of the power compound grease is the same, then based on Weibull The distribution builds the initial model. Preferably, the Weibull distribution-based accelerated aging model of electric compound grease is:

lnη=a ₁ +a ₂ I(1+ε)R+b ₁ /T+b ₂ I(1+ε)/T,

Among them, η is the Weibull distribution characteristic life, T is the absolute temperature, I is the current passing through the test object, R is the resistance value of the electrical connection without coating the electric compound grease, εR is the electrical connection resistance after the electric compound grease is applied The change in value, a1, a2, b1 and b2 are constants.

Preferably, at step 104, multiple linear regression analysis is performed on the initial parameters in the initial model according to the data of the resistance value and the temperature rise value under each of the various operating conditions, so as to determine the acceleration of the electric compound grease based on the Weibull distribution Aging model.

FIG. 2 is a flowchart of a method 200 for establishing an accelerated aging model of an electrical compound grease according to another embodiment of the present invention. As shown in FIG. 2 , method 200 begins with step 201 . Preferably, at step 201, a combined thermoelectric test is performed on the DUT coated with the power compound grease under various operating conditions using a test circuit. Preferably, the combined thermoelectric test obtains the data of the resistance value and the temperature rise value of the test object under each working condition in various working conditions, so as to determine the linear interval and inflection point of the resistance value or the temperature rise value under each working condition value.

Preferably, at step 202, it is determined whether an inflection point occurs in one of the resistance value or the temperature rise value. Preferably, the combined thermoelectric test is stopped when an inflection point occurs in either the resistance value or the temperature rise value. Alternatively, when there is no inflection point in both the resistance value and the temperature rise value, increase the current through the DUT until an inflection point occurs in either the resistance value or the temperature rise value, and stop the combined thermoelectric test (described in detail below). Preferably, the object to be tested may be an electrode coated with electrical compound grease.

Preferably, at step 203, the combined heat and power test ends and the test data is analyzed.

Preferably, at step 204, a statistical law of electrical complex lipid aging is determined. And at step 205, a hypothesis test is performed on the statistical law. Preferably, if the statistical law passes the hypothesis test, a model is established (which will be described in detail below); if the statistical law fails the hypothesis test, return to step 204 . (detailed below) If and preferably, the method 200 uses a Weibull distribution to analyze the aging distribution characteristics of the electrical compound grease. Among them, the statistical analysis of aging data of Weibull distribution is based on the following two premises:

A1. Under each test level, the aging of the power compound grease obeys the Weibull distribution, that is, the aging distribution type does not change with the change of the accelerated test level; and

A2. Under different test levels, the aging failure mechanism of power compound grease must be consistent.

If the assumptions A1 and A2 are satisfied, it can be determined that the aging of the power compound grease follows a Weibull distribution. According to the aging test data of the power compound grease under different working conditions, using the wblplot function of the MATLAB statistical function to analyze the data, the Weibull probability diagram under each test point can be drawn. The life data of the electric compound grease samples at the same test temperature are grouped into one group and plotted on the Weibull probability map. Since there are n different test current levels at each test temperature, there are n Weibull probability lines on each Weibull probability map. If the lifetime probability data points of n samples of the electrical compound grease are all approximately around the same straight line in the Weibull probability plot at a current and temperature level, it can be assumed that the aging data of the electrical compound grease sample satisfies the assumption of the Weibull distribution A1 and A2, the sample lifetime obeys Weibull distribution.

Preferably, at step 206, an initial model is established based on the Weibull distribution. Preferably, the failure time when both the electrical and thermal factors are added to the electrical compound grease at the same time is much shorter than the failure time when they are applied individually. This addition is not a simple algebraic superposition of thermal and electrical aging, so the combined electro-thermal accelerated life model must consider the interaction between the two factors. At step 206, the present application determines a combined accelerated aging model of electric power compound grease, which is derived as follows:

lnη=a+b/T (1)

a=a ₁ +a ₂ I(1+ε)R (2)

b=b ₁ +b ₂ I(1+ε)R (3)

Let U=I(1+ε)R

lnη=(a ₁ +a ₂ U)+(b ₁ +b ₂ U)/T (4)

It is further deduced from Equation 4

lnη=a ₁ +a ₂ I(1+ε)R+b ₁ /T+b ₂ I(1+ε)/T (5)

Among them, η is the Weibull distribution characteristic life, T is the absolute temperature, I is the current passing through the test object, R is the resistance value of the electrical connection without coating the electric compound grease, εR is the electrical connection resistance after the electric compound grease is applied The change in value, a1, a2, b1 and b2 are constants.

It can be seen from formula (5) that if lnη is regarded as the dependent variable, and I, T, εR are regarded as three independent variables, the model can be converted into a standard multiple linear regression model formula. Using the combined thermal and electric test data, combined with the given model, the multiple linear regression estimation of the model parameters can be realized by MATLAB programming, and the specific expression of the life prediction model of the power compound grease can be obtained.

Preferably, at step 207, multiple linear regression analysis is performed on the initial parameters in the initial model according to the data of the resistance value and the temperature rise value under each of the multiple operating conditions.

Preferably, at step 208, if the initial parameters in the initial model meet the requirements, the initial model is determined to be a Weibull distribution-based accelerated aging model for electrical compound grease.

FIG. 3 is a schematic structural diagram of a test circuit according to an embodiment of the present invention. As shown in FIG. 3 , the test circuit 300 includes: a 220V AC power supply 301 , a self-coupling voltage regulator 302 , a step-down transformer 303 , a protection resistor 304 , a coupling capacitor 305 , a combined thermoelectric test box 306 , a product to be tested 307 , and a ground wire 308 and ground terminal 309 .

Preferably, the 220V AC power supply 301 is an input power supply, which is connected to both ends of the self-coupling voltage regulator. Preferably, a self-coupled voltage regulator 302 is used to adjust the test voltage. Preferably, one end of the primary side of the step-down transformer 303 is connected to the adjustable end of the self-coupling voltage regulator 302 for reducing the voltage. The other end of the primary side of the step-down transformer 303 is grounded. Preferably, the protection resistor 304, which plays the role of current limiting protection, is connected to one end of the secondary side of the step-down transformer 303. One end of the coupling capacitor 305 and the protection resistor 304 and the other end of the secondary side of the step-down transformer 303 are used to return the test voltage to the console for display. Preferably, one end of the combined heat and power test box 306 is connected to one end of the coupling capacitor, and the other end of the combined heat and power test box 306 is grounded. The combined thermoelectric test box 306 is used for accommodating the object to be tested, and its internal size is 1000×1000×1000 (mm), the adjustable temperature range is -60～100°C, and the temperature fluctuation degree is ±0.2°C. Preferably, the DUT 307 includes a test electrode and a sample. Wherein the sample can be a power complex grease. Preferably, the ground wire 308 is used for the connection between the ground terminal and the ground electrode. The ground terminal 309 of the combined heat and power test box is used for grounding the test.

Preferably, during the test, the aging temperature of the power compound grease sample can be controlled by adjusting the internal temperature of the combined heat and power test chamber. During the test, the uniformity of the internal temperature of the combined heat-electric test box should be ensured, so as to achieve the purpose of conducting the combined electric-heat combined accelerated aging test of the sample in the test box during the test.

Preferably, the test can be divided into the following several working conditions, and the test flow is shown in Figure 4. 4 is a flow chart of an accelerated aging test according to an embodiment of the present invention. Preferably, the test steps are as follows:

Step 401 , before the test, test the resistance value of the object to be tested and then place the object to be tested in a combined thermoelectric test box.

Step 402 , according to the temperature rise value of 130Tt/°C, the current is connected to the test object, the internal temperature of the combined heat and power test chamber is controlled to vary between 20°C and 22°C, and the current-on time h=3 hours.

Step 403 , measure the contact resistance value R1 and the temperature rise value K1 of the DUT.

Step 404, repeat steps 402-403 for a total of 19 times (a total of 60 hours), and record the resistance value and temperature rise value of each test.

In step 405, it is determined whether the resistance value or the temperature rise value of the DUT increases linearly, that is, it is determined whether there is an inflection point value.

Step 406, if the resistance value or temperature rise value of the product to be tested has an inflection point, then stop the test, otherwise, in step 407, according to the temperature rise value of 150Tt/℃, the current is connected to the product to be tested, and the internal temperature of the combined thermoelectric test box is controlled at 20 °C Changes between ~22°C, current passing time h=3 hours.

Step 408, repeat step 407 for a total of 20 times (60 hours in total), and record the resistance value and temperature rise value of each test.

Step 409 , determine whether the resistance value or the temperature rise value of the DUT increases linearly, that is, determine whether there is an inflection point value.

In step 410, if the resistance value or temperature rise value of the product to be tested has an inflection point, the test is stopped; otherwise, in step 411, the current is connected to the product to be tested according to the temperature rise value of 170Tt/°C, and the internal temperature of the combined thermoelectric test box is controlled at 20°C. Changes between ~22°C, current passing time h=3 hours.

Step 412, repeat step 411 for a total of 20 times (60 hours in total), and record the resistance value and temperature rise value of each test.

Step 413 , determine whether the resistance value or the temperature rise value of the DUT increases linearly, that is, determine whether there is an inflection point value.

Step 414, if the resistance value or temperature rise value of the product to be tested has an inflection point, then stop the test, otherwise, in step 415, according to the temperature rise value of 190Tt/℃, the current is connected to the product to be tested, and the internal temperature of the combined thermoelectric test box is controlled at 20 °C Changes between ~22°C, current passing time h=3 hours.

Step 416, repeat step 415 for a total of 20 times (60 hours in total), and record the resistance value and temperature rise value of each test.

Step 417 ends.

FIG. 5 is a flowchart of a method 500 for performing a combined thermoelectric test on a test sample coated with a power compound grease according to another embodiment of the present invention. The method 500 utilizes a test circuit to perform a combined thermoelectric test on a DUT coated with a power compound grease under various operating conditions. Preferably, the combined thermoelectric test obtains the data of the resistance value and the temperature rise value of the test object under each working condition in various working conditions, so as to determine the linear interval and inflection point of the resistance value or the temperature rise value under each working condition value.

Preferably, method 500 determines whether an inflection point occurs in one of the resistance value or the temperature rise value. Preferably, the combined thermoelectric test is stopped when an inflection point occurs in either the resistance value or the temperature rise value. Or, when there is no inflection point in both the resistance value and the temperature rise value, increase the current passing through the test object until the resistance value or the temperature rise value has an inflection point, and stop the combined thermoelectric test. Preferably, the object to be tested may be an electrode coated with electrical compound grease.

Preferably, in step 501, the resistance value of the DUT coated with the power compound grease is measured. Usually, it is necessary to measure the resistance value of the DUT coated with the power compound grease before the combined thermoelectric test is carried out, as the measurement basis for the increase of the resistance value.

Preferably, in step 502, the DUT coated with the electrical compound grease is placed in a combined thermoelectric test chamber. The combined thermoelectric test box is used to accommodate the test object, and its internal size is 1000×1000×1000 (mm), the adjustable temperature range is -60～100°C, and the temperature fluctuation is ±0.2°C. Preferably, the internal temperature of the combined heat and power test box is controlled at 20°C to 22°C.

Preferably, in step 503, the voltage of the input power supply is adjusted to obtain an adjusted test voltage. For example, take a 220V AC power supply as the input power supply, which is connected to both ends of the self-coupled voltage regulator. The method 500 uses a self-coupling voltage regulator to regulate the test voltage. In addition, one end of the primary side of the step-down transformer is connected to the adjustable end of the self-coupling voltage regulator for reducing the voltage. The other end of the primary side of the step-down transformer is grounded. Preferably, one end of the combined heat and power test box is connected to one end of the coupling capacitor, and the other end of the combined heat and power test box is grounded.

Preferably, in step 504, the regulated test voltage is connected to the combined heat and power test box to supply power to the combined heat and power test box and the DUT in the combined heat and power test box.

Preferably, in step 505, a combined thermoelectric test is performed on the DUT coated with the power compound grease under the current operating conditions. For example, according to the temperature rise value of 130Tt/°C, the current is connected to the test object, the internal temperature of the combined heat and power test box is controlled to change between 20°C and 22°C, and the current-on time h=3 hours. Measure the contact resistance value R1 and temperature rise value K of the product to be tested, and repeat the above steps for a total of 19 times (60 hours in total), and record the resistance value and temperature rise value of each test.

Preferably, in step 506, the real-time data of the resistance value and the real-time data of the temperature rise value of the DUT under the current working condition are obtained.

Preferably, in step 507, it is determined whether the real-time data of the resistance value or the temperature rise value of the DUT is a linear increase.

Preferably, in step 508, if the real-time data of the resistance value or the temperature rise value does not increase linearly, the combined heat and power test is stopped.

Preferably, in step 509, if the real-time data of the resistance value or the temperature rise value increases linearly, the combined thermoelectric test is performed on the test object coated with the power compound grease under the next working condition, until the real-time data of the resistance value or the temperature rise value increases. When one of the data does not increase linearly, stop the combined heat and power test. Preferably, the next working condition is, for example: according to the temperature rise value of 150Tt/℃, the current is connected to the test object, the internal temperature of the combined heat and power test box is controlled to change between 20 °C and 22 °C, and the current passing time is h=3 hours; according to The temperature rise value is 170Tt/℃, the current is connected to the test object, the internal temperature of the combined thermoelectric test box is controlled to change between 20℃～22℃, the current passing time is h=3 hours; and the test object is connected according to the temperature rise value 190Tt/℃ The internal temperature of the combined current and heat and power test box is controlled to vary between 20°C and 22°C, and the current-on time h=3 hours.

FIG. 6 is a schematic structural diagram of a system 600 for performing a combined thermoelectric test on a test sample coated with electrical compound grease according to another embodiment of the present invention. The system 600 uses a test circuit to perform a combined thermoelectric test on the DUT coated with the power compound grease under various operating conditions. Preferably, the combined thermoelectric test obtains the data of the resistance value and the temperature rise value of the test object under each working condition in various working conditions, so as to determine the linear interval and inflection point of the resistance value or the temperature rise value under each working condition value.

As shown in FIG. 1 , the system 600 includes: a resistance measurement unit 601 , a combined heat and power test box 602 , a voltage adjustment unit 603 , a voltage input unit 604 and a test unit 605 . The resistance measurement unit 601 is used to measure the resistance value of the DUT coated with the power compound grease. Usually, it is necessary to measure the resistance value of the DUT coated with the power compound grease before the combined thermoelectric test is carried out, as the measurement basis for the increase of the resistance value.

Preferably, the combined thermoelectric test box 602 is used to accommodate the test object coated with the electrical compound grease. The combined thermoelectric test box 602 is used for accommodating the object to be tested, and its internal size is 1000×1000×1000 (mm), the adjustable temperature range is -60～100°C, and the temperature fluctuation degree is ±0.2°C. Preferably, the internal temperature of the combined heat and power test box 602 is controlled at 20°C to 22°C.

Preferably, the voltage adjustment unit 603 is used to adjust the voltage of the input power supply to obtain the adjusted test voltage. For example, take a 220V AC power supply as the input power supply, which is connected to both ends of the self-coupled voltage regulator. System 600 uses a self-coupling voltage regulator to regulate the test voltage. In addition, one end of the primary side of the step-down transformer is connected to the adjustable end of the self-coupling voltage regulator for reducing the voltage. The other end of the primary side of the step-down transformer is grounded. Preferably, one end of the combined heat and power test box is connected to one end of the coupling capacitor, and the other end of the combined heat and power test box is grounded.

Preferably, the voltage input unit 604 connects the regulated test voltage to the combined heat and power test box, so as to supply power to the combined heat and power test box and the DUT in the combined heat and power test box.

Preferably, the test unit 605 performs a combined thermoelectric test on the DUT coated with the power compound grease under the current working condition, obtains real-time data of the resistance value and real-time data of the temperature rise value of the DUT under the current working condition, and determines Whether the real-time data of the resistance value or temperature rise value of the test object increases linearly; and if the real-time data of the resistance value or temperature rise value does not increase linearly, stop the combined thermoelectric test. Among them, the current working conditions are, for example, the current is connected to the test object according to the temperature rise value of 130Tt/℃, the internal temperature of the combined heat and power test box is controlled to change between 20°C and 22°C, and the current-on time h=3 hours. Among them, the next working condition is, for example, according to the temperature rise value of 150Tt/℃, the current is connected to the test object, the internal temperature of the combined thermoelectric test box is controlled to change between 20℃～22℃, and the current passing time is h=3 hours; according to the temperature rise value of 170Tt /℃ The current is connected to the test object, the internal temperature of the combined thermoelectric test box is controlled to change between 20℃～22℃, the current passing time is h=3 hours; The internal temperature of the combined test box was controlled to vary between 20°C and 22°C, and the current-carrying time h=3 hours.

Preferably, according to the preferred embodiment of the present invention, the selection of the next working condition may be gradually selected according to the increase of the temperature rise value, until the real-time data of the resistance value or the temperature rise value does not increase linearly, that is, an inflection point occurs. The present invention has been described with reference to a few embodiments. However, as is known to those skilled in the art, other embodiments than the above disclosed invention are equally within the scope of the invention, as defined by the appended patent claims.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/the/the [means, component, etc.]" are open to interpretation as at least one instance of said means, component, etc., unless expressly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Claims (6)

1. A method for modeling electrical composite grease accelerated aging, the method comprising:

the method comprises the following steps of carrying out a combined heat and power test on a to-be-tested sample coated with electric composite grease under various working conditions by using a test circuit, obtaining data of a resistance value and a temperature rise value of the to-be-tested sample under each working condition in the various working conditions, and determining a linear interval and an inflection point value of the resistance value or the temperature rise value under each working condition, wherein the data comprises the following steps:

the test circuit is used for carrying out the combined heat and power test on the to-be-tested sample coated with the electric composite grease under various working conditions,

acquiring real-time data of the resistance value and the temperature rise value of the to-be-tested sample under the current working condition, and determining whether the resistance value or the real-time data of the temperature rise value of the to-be-tested sample is linearly increased or not; and stopping the combined heat and power test if the real-time data of the resistance value or the temperature rise value is not linearly increased;

if the test unit determines that the real-time data of the resistance value or the temperature rise value is linearly increased, performing a combined heat and power test on the to-be-tested sample coated with the electric composite grease under the next working condition, and stopping the combined heat and power test until one of the real-time data of the resistance value or the temperature rise value is not linearly increased;

determining whether a difference between the resistance value or the inflection point value of the temperature increase value for each of the plurality of operating conditions is within a predetermined range,

if the difference value between the inflection point values of the resistance value or the temperature rise value under each working condition in the multiple working conditions is within a preset range and the aging principle of the power compound grease is the same, establishing an initial model based on Weibull distribution; the electric composite grease accelerated aging model based on Weibull distribution is as follows:

lnη＝a₁+a₂I(1+)R+b₁/T+b₂I(1+)/T，

wherein eta is the characteristic life of Weibull distribution, T is the absolute temperature, I is the current passing through the sample to be tested, R is the resistance value of the electric connection part without being coated with the electric composite grease, R is the change value of the resistance value of the electric connection part after being coated with the electric composite grease, and a1, a2, b1 and b2 are constants;

performing multiple linear regression analysis on initial parameters in the initial model according to data of the resistance value and the temperature rise value under each working condition in multiple working conditions to determine a power composite grease accelerated aging model based on Weibull distribution;

wherein the test circuit comprises: the device comprises a 220V alternating current power supply, a self-coupling voltage regulator, a step-down transformer, a protective resistor, a coupling capacitor, a combined heat and power test box, a to-be-tested sample, a grounding wire and a grounding end;

the 220V alternating current power supply is an input power supply and is connected to two ends of the self-coupling voltage regulator;

the self-coupling voltage regulator is used for regulating the test voltage;

one end of the primary side of the step-down transformer is connected to the adjustable end of the self-coupling regulator and used for reducing voltage, and the other end of the primary side of the step-down transformer is grounded;

the protective resistor plays a role of current-limiting protection and is connected to one end of the secondary side of the step-down transformer;

the coupling capacitor is connected with one end of the protective resistor and the other end of the secondary side of the step-down transformer and used for returning the test voltage to the console for displaying;

one end of the combined heat and power test box is connected with one end of the coupling capacitor, the other end of the combined heat and power test box is grounded, the combined heat and power test box is used for accommodating a to-be-tested sample, the inner size of the combined heat and power test box is 1000 multiplied by 1000mm, the adjustable temperature range is-60-100 ℃, and the temperature fluctuation degree is +/-0.2 ℃;

the test sample to be tested comprises a test electrode and a sample, wherein the sample is the electric composite grease;

the grounding wire is used for connecting the grounding end with the grounding electrode;

and the grounding end is used for grounding in a test mode.

2. The method as claimed in claim 1, wherein the performing, by using the test circuit, the combined heat and power test on the sample coated with the electrical compound grease under multiple working conditions to obtain data of the resistance value and the temperature rise value of the sample under each of the multiple working conditions, so as to determine the linear interval and the inflection point value of the resistance value or the temperature rise value under each working condition, includes:

the method comprises the steps of carrying out a combined heat and power test on a to-be-tested sample coated with electric composite grease under various working conditions by using a test circuit, obtaining data of a resistance value and a temperature rise value of the to-be-tested sample under each working condition in the various working conditions, and stopping the combined heat and power test when an inflection point appears in one of the resistance value or the temperature rise value.

3. The method as claimed in claim 1, wherein the performing, by using the test circuit, the combined heat and power test on the sample coated with the electrical compound grease under multiple working conditions to obtain data of the resistance value and the temperature rise value of the sample under each of the multiple working conditions, so as to determine the linear interval and the inflection point value of the resistance value or the temperature rise value under each working condition, includes:

the method comprises the steps of carrying out thermoelectric combined test on a to-be-tested sample coated with electric composite grease under various working conditions by using a test circuit, obtaining data of a resistance value and a temperature rise value of the to-be-tested sample under each working condition in the various working conditions, increasing current passing through the to-be-tested sample when no inflection point appears in the resistance value and the temperature rise value, and stopping the thermoelectric combined test until the inflection point appears in one of the resistance value or the temperature rise value.

4. A system for establishing an electrical composite grease accelerated aging model, the system comprising:

the device comprises an obtaining device, a test circuit and a control device, wherein the obtaining device is used for carrying out a combined heat and power test on a to-be-tested sample coated with electric composite grease under various working conditions by utilizing the test circuit to obtain data of a resistance value and a temperature rise value of the to-be-tested sample under each working condition in various working conditions so as to determine a linear interval and an inflection point value of the resistance value or the temperature rise value under each working condition;

the test device is used for carrying out a combined heat and power test on a to-be-tested sample coated with the electric composite grease under various working conditions by using a test circuit, obtaining real-time data of the resistance value and the temperature rise value of the to-be-tested sample under the current working condition, and determining whether the real-time data of the resistance value or the temperature rise value of the to-be-tested sample is linearly increased or not; and stopping the combined heat and power test if the real-time data of the resistance value or the temperature rise value is not linearly increased; if the test unit determines that the real-time data of the resistance value or the temperature rise value is linearly increased, performing a combined heat and power test on the to-be-tested sample coated with the electric composite grease under the next working condition, and stopping the combined heat and power test until one of the real-time data of the resistance value or the temperature rise value is not linearly increased;

a determination device that determines whether a difference between the resistance value or the inflection point value of the temperature increase value in each of the plurality of operating conditions is within a predetermined range,

the device for establishing the electric power composite grease comprises a device for establishing an initial model based on Weibull distribution if the difference value between the inflection point values of the resistance value or the temperature rise value under each working condition in a plurality of working conditions is within a preset range and the aging principle of the electric power composite grease is the same; the electric composite grease accelerated aging model based on Weibull distribution is as follows:

lnη＝a₁+a₂I(1+)R+b₁/T+b₂I(1+)/T，

wherein eta is the characteristic life of Weibull distribution, T is the absolute temperature, I is the current passing through the sample to be tested, R is the resistance value of the electric connection part without being coated with the electric composite grease, R is the change value of the resistance value of the electric connection part after being coated with the electric composite grease, and a1, a2, b1 and b2 are constants; performing multiple linear regression analysis on initial parameters in the initial model according to data of the resistance value and the temperature rise value under each working condition in multiple working conditions to determine a Weibull distribution-based electric power compound grease accelerated aging model

Wherein the test circuit comprises: the device comprises a 220V alternating current power supply, a self-coupling voltage regulator, a step-down transformer, a protective resistor, a coupling capacitor, a combined heat and power test box, a to-be-tested sample, a grounding wire and a grounding end;

the 220V alternating current power supply is an input power supply and is connected to two ends of the self-coupling voltage regulator;

the self-coupling voltage regulator is used for regulating the test voltage;

one end of the primary side of the step-down transformer is connected to the adjustable end of the self-coupling regulator and used for reducing voltage, and the other end of the primary side of the step-down transformer is grounded;

the protective resistor plays a role of current-limiting protection and is connected to one end of the secondary side of the step-down transformer;

the coupling capacitor is connected with one end of the protective resistor and the other end of the secondary side of the step-down transformer and used for returning the test voltage to the console for displaying;

one end of the combined heat and power test box is connected with one end of the coupling capacitor, the other end of the combined heat and power test box is grounded, the combined heat and power test box is used for accommodating a to-be-tested sample, the inner size of the combined heat and power test box is 1000 multiplied by 1000mm, the adjustable temperature range is-60-100 ℃, and the temperature fluctuation degree is +/-0.2 ℃;

the test sample to be tested comprises a test electrode and a sample, wherein the sample is the electric composite grease;

the grounding wire is used for connecting the grounding end with the grounding electrode;

and the grounding end is used for grounding in a test mode.

5. The system as claimed in claim 4, wherein the obtaining device performs the combined heat and power test on the test object coated with the electrical compound grease under a plurality of working conditions by using the test circuit, obtains data of the resistance value and the temperature rise value of the test object under each working condition, and stops the combined heat and power test when an inflection point appears in one of the resistance value or the temperature rise value.

6. The system as claimed in claim 4, wherein the obtaining device performs the combined heat and power test on the sample coated with the electric compound grease under a plurality of operating conditions by using the test circuit, obtains data of the resistance value and the temperature rise value of the sample under each operating condition, and increases the current passing through the sample when the resistance value and the temperature rise value do not have an inflection point, and stops the combined heat and power test until the inflection point appears in one of the resistance value and the temperature rise value.

Images