Method for evaluating safety of residual air leakage voltage and low-pressure discharge of thyristor in vacuum environment
By testing the leakage rate change relationship and internal air pressure of the thyristor, the residual air leakage pressure and low air pressure discharge risks of the thyristor in a vacuum environment are evaluated, and the problem of evaluation in the existing technology is solved, and the safety and life of the thyristor are achieved. Accurate assessment.
Patent Information
- Application Number
- CN202411373299.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-29
- Publication Date
- 2024-12-27
AI Technical Summary
The prior art is difficult to accurately evaluate the safety of gas-sealed high-power thyristors in vacuum environments, resulting in difficulty in evaluating safety and life.
By testing the leakage rate of the thyristor over time, determining the internal air pressure changes over time, calculating the residual air leakage pressure under the service life, defining the safety threshold for low-pressure discharge, and evaluating the risk of low-pressure discharge and the maximum safety life of the thyristor.
The accuracy and reliability of the safety evaluation of residual pressure and low air pressure discharge in the thyristor vacuum environment is achieved, and the safety and life evaluation accuracy of sealed devices is significantly improved.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention relates to a method for evaluating the safety of low-pressure discharge of a thyristor, and in particular to a method for evaluating the residual pressure of leakage and the safety of low-pressure discharge of a thyristor in a vacuum environment. Background Art
[0002] High-voltage and high-power semiconductor devices are widely used in power systems, charging power supplies, batteries, new energy vehicles, electric locomotives, ships and submarines, aerospace and other fields. In order to improve the stability, reliability, environmental adaptability and life of semiconductor devices, semiconductor devices such as thyristors, MOSFET and other sealed devices are all sealed and packaged, and the sealed device is filled with protective gases such as dry nitrogen at a certain pressure. When stored or used for a long time in a vacuum environment, there is always a certain leakage rate in the sealed device. Under the pressure difference between the internal and external air pressures, the protective gas sealed inside the sealed device will slowly leak into the external vacuum environment; when the air pressure inside the sealed device drops to a certain level due to long-term leakage, according to the Baschen curve, when the semiconductor device is working, high voltages are applied to both ends of the high-voltage electrode and the low-voltage electrode, and low-pressure breakdown discharge problems may occur, resulting in serious faults such as burning of the semiconductor device and short circuits in the associated circuits.
[0003] How to accurately and conveniently evaluate and analyze the gas leakage law of sealed high-voltage and high-power semiconductor devices such as thyristors under vacuum, evaluate the relationship between the internal residual pressure and the low-pressure discharge pressure threshold of gas-sealed thyristors during use, and then establish a set of methods to accurately evaluate the low-pressure discharge risk and safe service life of gas-sealed thyristors under vacuum environment, is of great significance and practical value to improving the safety and reliability of sealed devices.
[0004] Affected by factors such as thyristor sealing structure, sealing process stability, and product production batch dispersion, the leakage rate of thyristors in a vacuum environment is highly dispersed, and the law of leakage rate changing with the gas pressure inside the thyristor is complex. However, there is a certain range of thyristor low-pressure discharge pressure under working voltage. At present, there are few research reports on the residual pressure of leakage and the safety assessment method of low-pressure discharge when gas-sealed high-power thyristors are used in a vacuum environment. Summary of the invention
[0005] The purpose of the present invention is to solve the technical problem that it is difficult to evaluate the safety of leakage residual pressure and low-pressure discharge of existing gas-sealed high-power thyristors when used in a vacuum environment, and to provide a method for evaluating the safety of leakage residual pressure and low-pressure discharge of thyristors in a vacuum environment.
[0006] In order to achieve the above object, the present invention adopts the following technical solution:
[0007] A method for evaluating the leakage residual pressure and low-pressure discharge safety of thyristors in a vacuum environment, characterized in that it includes the following steps:
[0008] S1. Measure the leakage rate of the original sealed gas in the thyristor;
[0009] S2. Determine the relationship between the measured leakage rate of the thyristor and the leakage time, and obtain the coefficient n;
[0010] S3. Determine the relationship between the internal air pressure P(t) of the thyristor and time according to the relationship between the measured leakage rate of the thyristor and the leakage time and the coefficient n;
[0011] S4. Calculate the service life T according to the relationship between the internal air pressure P(t) of the thyristor and time life The internal leakage residual pressure P(T life ) of the thyristor below;
[0012] S5. Determine the low-pressure discharge safety of the thyristor:
[0013] Define the lower limit threshold of the air pressure at which no low-voltage discharge occurs inside the thyristor as P;
[0014] If P(T life ) < P, then the thyristor at the service life T life has a risk problem of low-pressure discharge caused by air leakage;
[0015] If P(T life ) ≥ P, then the thyristor at the service life T life can be used safely and there is no risk problem of low-pressure discharge caused by air leakage, and the evaluation of the leakage residual pressure and low-pressure discharge safety is completed.
[0016] Furthermore, when the thyristor can be used safely and there is no risk problem of low-pressure discharge caused by air leakage, it also includes:
[0017] S6. Determine the longest safe life of the thyristor.
[0018] Furthermore, step S1 is specifically:
[0019] 1.1. Define the internal air pressure and its volume of the sealed gas in the internal cavity of the gas-sealed thyristor at room temperature and atmospheric pressure as P0 and ΔV respectively;
[0020] P0 = m × 1.01 × 10 5 Pa
[0021] where m represents the number of atmospheric pressures, m ≥ 1;
[0022] 1.2. Place the thyristor with an internal air pressure of P0 in a helium tank for T0 time, and keep the helium pressure in the helium tank at P0 + m × 1.01 × 105 Pa; 5≤T0<10;
[0023] 1.3. Take out the thyristor from the helium tank and put it into the vacuum tank of the helium mass spectrometer leak rate tester. After standing for T0 time, read the thyristor test leak rate Q1 detected by the helium mass spectrometer leak rate tester.
[0024] If the thyristor test leakage rate Q1≤1×10 -7 Pa·m 3 / s, then execute step 1.4; otherwise, the thyristor leakage rate does not meet the standard, and does not have the safety of low-pressure discharge and leakage life assessment value in a vacuum environment;
[0025] 1.4. Take out the thyristor from the vacuum tank of the helium mass spectrometer leak rate tester and place it in room temperature for at least 12 hours;
[0026] 1.5. Put the thyristor back into the helium tank and let it stand for T0 time, and keep the helium pressure in the helium tank at P0+(m+1)×1.01×10 5 Pa;
[0027] 1.6. Take out the thyristor from the helium tank and put it into the vacuum tank of the helium mass spectrometer leak rate tester. After standing for T0 time, read the thyristor test leak rate Q2 detected by the helium mass spectrometer leak rate tester.
[0028] Furthermore, step S2 is specifically as follows:
[0029] 2.1. Define the atomic weight of the gas sealed in the thyristor cavity as M and the atomic weight of helium as M He The external environment pressure when the thyristor is stored or working is P E , P E ≤P0; According to the thyristor test leakage rates Q1 and Q2, the relationship between the leakage rate Q(t) of the thyristor internal pressure P0 at the time of leakage t and the leakage time t is:
[0030]
[0031] Where, P(t) is the internal pressure of the thyristor at the time when P0 leaks;
[0032] 2.2. The coefficient n can be obtained from the relationship between the leakage rate Q(t) and the leakage time t:
[0033]
[0034] Furthermore, step S3 is specifically as follows:
[0035] According to the relationship between the leakage rate of the thyristor test and the leakage time and the coefficient n, the pressure P(t) inside the thyristor is determined at the external environment pressure P EThe relationship between the leakage time and the leakage time t is:
[0036]
[0037] Further, step S4 is specifically as follows:
[0038] Define the thyristor under external ambient pressure P E The validity period is T life , according to the pressure P(t) inside the thyristor under the external ambient pressure P E The following relationship between the leakage time t and the service life T can be obtained by the following formula life The residual pressure of the internal leakage of the rear thyristor P(T life );
[0039]
[0040] Furthermore, step S6 is specifically as follows:
[0041] Defined by the external ambient air pressure P E When the thyristor can be used safely without the risk of low-pressure discharge due to gas leakage, the maximum life T is calculated by the following formula: max ;
[0042]
[0043] Furthermore, in step 1.1, m=1; in step 1.2, T0=5.
[0044] Furthermore, in steps 1.3 and 1.6, the vacuum degree in the vacuum tank is less than or equal to 5×10 -3 Pa.
[0045] Further, in step S5, the value of P is 10 kPa.
[0046] Beneficial effects of the present invention:
[0047] 1. The present invention provides a method for evaluating the safety of residual pressure of leakage and low-pressure discharge of thyristors in a vacuum environment. By testing the leakage rate of the original sealed gas in the thyristor, determining the relationship between the leakage rate of the original sealed gas in the thyristor and the leakage time, determining the relationship between the pressure in the thyristor and the time, calculating the residual pressure of leakage inside the thyristor under the service life, and determining the safety and maximum safe life of the low-pressure discharge of the thyristor, the difficult problem of evaluating the safety and reliability of residual pressure of leakage and low-pressure discharge when the thyristor is used in a vacuum environment is solved, and the leakage law, residual pressure of leakage and safety margin of low-pressure discharge of the thyristor are accurately evaluated.
[0048] 2. The present invention provides a method for evaluating residual pressure of thyristor leakage and low-pressure discharge safety in a vacuum environment, which is simple and convenient, and significantly improves the accuracy of evaluation of leakage rules, life, and low-pressure discharge safety and reliability of gas-sealed power semiconductor devices. DETAILED DESCRIPTION
[0049] A method for evaluating the safety of residual pressure of leakage and low-pressure discharge of thyristors under vacuum environment comprises the following steps:
[0050] S1. Test the leakage rate of the gas originally sealed in the thyristor;
[0051] 1.1. Define the internal pressure and volume of the gas sealed in the internal cavity of the gas-sealed thyristor at room temperature and atmosphere as P0 and ΔV respectively;
[0052] P0=m×1.01×10 5 Pa
[0053] Where m represents the number of atmospheric pressures, m≥1;
[0054] 1.2. Place the thyristor with internal pressure P0 into the helium tank for T0 time, and keep the helium pressure in the helium tank at P0+m×1.01×10 5 Pa;
[0055] 1.3. Take out the thyristor from the helium tank and put it into the vacuum tank of the helium mass spectrometer leak rate tester. After standing for T0 time, read the thyristor test leak rate Q1 detected by the helium mass spectrometer leak rate tester. The vacuum degree in the vacuum tank is less than or equal to 5×10 -3 Pa;
[0056] If the thyristor test leakage rate Q1≤1×10 -7 Pa·m 3 / s, then execute step 1.4; otherwise, the thyristor leakage rate does not meet the standard, and does not have the safety of low-pressure discharge and leakage life assessment value in a vacuum environment;
[0057] 1.4. Take out the thyristor from the vacuum tank of the helium mass spectrometer leak rate tester and place it in room temperature for at least 12 hours;
[0058] 1.5. Put the thyristor back into the helium tank and let it stand for T0 time, and keep the helium pressure in the helium tank at P0+(m+1)×1.01×10 5 Pa;
[0059] 1.6. Take out the thyristor from the helium tank and put it into the vacuum tank of the helium mass spectrometer leak rate tester. After standing for T0 time, read the thyristor test leak rate Q2 detected by the helium mass spectrometer leak rate tester. The vacuum degree in the vacuum tank is less than or equal to 5×10 -3 Pa;
[0060] S2. Determine the relationship between the leakage rate of the original sealed gas in the thyristor and the leakage time based on the measured leakage rates Q1 and Q2 of the thyristor, and obtain the coefficient n;
[0061] 2.1. Define the atomic weight of the gas sealed in the internal cavity of the thyristor as M, and the atomic weight of helium as M He , and the external ambient air pressure when the thyristor is stored or operating is P E , P E ≤P0; The relationship between the leakage rate Q(t) and the leakage time t at the time of leakage of the internal air pressure P0 of the thyristor obtained from the measured leakage rates Q1 and Q2 of the thyristor is:
[0062]
[0063]
[0064] In the formula, P(t) is the internal air pressure at the time t of leakage of the internal air pressure P0 of the thyristor;
[0065] 2.2. The coefficient n can be obtained from the relationship between the leakage rate Q(t) and the leakage time t as:
[0066]
[0067] S3. Determine the relationship between the internal air pressure P(t) of the thyristor and the leakage time t under the external ambient air pressure P E as:
[0068]
[0069] S4. Define the service life of the thyristor under the external ambient air pressure P E as T life , and according to the relationship between the internal air pressure P(t) of the thyristor and the leakage time t under the external ambient air pressure P E , the service life T life and the residual air pressure P(T life ) after internal air leakage of the thyristor can be obtained through the following formula;
[0070]
[0071] S5. Determine the low-pressure discharge safety of the thyristor:
[0072] Define the lower limit threshold of the air pressure at which no low-voltage discharge occurs inside the thyristor as P;
[0073] If P(T life ) < P, then the thyristor under the service life T life has a risk problem of low-pressure discharge caused by air leakage;
[0074] If P(T life )≥P, then the useful life is T life The thyristors under the test can be used safely without the risk of low-pressure discharge caused by leakage. The safety assessment of leakage residual pressure and low-pressure discharge is completed.
[0075] S6, defined as the external ambient air pressure P E When the thyristor can be used safely without the risk of low-pressure discharge due to gas leakage, the maximum life T is calculated by the following formula: max ;
[0076]
[0077] In this embodiment, the existing flat sealed DC1600V500A thyristor is processed according to the method of the present invention, specifically as follows:
[0078] (1) Testing the leakage rate of the gas originally sealed in the sealed thyristor;
[0079] The internal pressure of the sealed gas in the sealed thyristor cavity at room temperature is defined as P0, P0 = m × 1.01 × 10 5 Pa, where m = 1; the volume of the sealed gas in the sealed thyristor is ΔV = 8 × 10 -6 m 3 ;
[0080] Place the sealed thyristor with an internal pressure of P0 into a helium tank and keep the helium pressure in the tank at 2.02×10 5 Pa, the sealed thyristor was placed in the helium tank for T0 = 5 hours; then the thyristor was taken out and placed in the vacuum tank of the helium mass spectrometer leak rate tester for 5 hours, and the vacuum degree in the vacuum tank was 2×10 -3 Pa; the thyristor test leak rate detected by the helium mass spectrometer leak rate tester is Q1=7×10 -9 Pa·m 3 / s; take out the sealed thyristor and place it in room temperature atmosphere for 12.5 hours;
[0081] The same thyristor was placed in the helium tank again, and the helium pressure in the tank was maintained at 3.03×10 5 Pa, the thyristor was placed in the helium tank for T0 = 5 hours; then the thyristor was taken out and placed in the vacuum tank of the helium mass spectrometer leak rate tester for 5 hours, and the vacuum degree in the vacuum tank was 3×10 -3 Pa; the thyristor test leak rate detected by the helium mass spectrometer leak rate tester is Q2 = 1.67 × 10 -8 Pa·m 3 / s;
[0082] (2) Determine the relationship between the leakage rate of the gas originally sealed in the thyristor and the leakage time and obtain the coefficient n;
[0083] At the thyristor test leakage rate Q1 and Q2 levels, the leakage gas flow is approximately molecular flow; the gas sealed inside the thyristor is pure nitrogen (N2), whose atomic weight is M=28, and the atomic weight of helium is M He =4;
[0084] The external ambient pressure P of the sealed thyristor E ≈0; define the leakage time of nitrogen sealed inside the thyristor as t, and the leakage rate as Q(t); due to the leakage, the gas pressure inside the thyristor leaks from the initial P0 to P(t) after t;
[0085] Working at external ambient pressure P E Under this condition, the leakage rate Q(t) of nitrogen sealed inside the sealed thyristor varies with the leakage time t as follows: Q(t) = 2.64 × 10 -53.6 P(t) 8.92 , n = 8.92;
[0086] (3) According to the relationship between the leakage rate of the thyristor test and the leakage time and the coefficient n, determine the pressure P(t) inside the thyristor at the external environment pressure P E The relationship between the leakage time and the leakage time t is given by the following transcendental integral equation:
[0087]
[0088] (4) Define the external ambient pressure P of the thyristor E The validity period is T life 6 years (1.89×10 8 s), according to the pressure P(t) inside the thyristor at the external ambient pressure P E The following relationship between the leakage time t and the service life T can be obtained by the following formula life The residual pressure of the internal leakage of the rear thyristor P(T life );
[0089]
[0090] The predicted residual nitrogen pressure P(T) inside the thyristor after 6 years of use in vacuum environment is obtained. life )=82.5kPa;
[0091] (5) Determine the safety of thyristor low-pressure discharge;
[0092] The lower pressure threshold for low-voltage discharge inside the thyristor is generally 10 kPa. The nitrogen residual pressure P(Tlife ) and 10kPa: P(T life =6 years)>>10kPa, the service life is estimated to be T life = Sealed thyristors can be used safely for 6 years without the risk of low-pressure discharge due to leakage;
[0093] (6) Defined by the external ambient pressure P E When the thyristor can be used safely without the risk of low-pressure discharge due to gas leakage, the maximum life T is calculated by the following formula: max ;
[0094]
[0095] That is, T max =2727 years.
[0096] Even if the thyristor is considered to be leaking at the maximum leakage rate under the internal pressure P0, the maximum safe service life of the thyristor is T max Estimate according to the following formula:
[0097]
[0098] That is, T max ≥12.27 years.
[0099] The method of the present invention is used to evaluate and predict the leakage rate and internal leakage residual pressure of the flat sealed DC1600V500A thyristor implemented according to the method of the present invention. The thyristor is sealed with 101kPa nitrogen gas from the factory. The leakage rate of the helium mass spectrometer is 7×10 -9 Pa·m 3 / s, and then the thyristor was stored in a vacuum environment for 4 years. Then it was taken out and re-tested with a helium mass spectrometer in the same way. The test leakage rate of the thyristor was 1.7×10 -9 Pa·m 3 / s, the test results are basically consistent with the leak rate results predicted by the method of the present invention, indicating that the method of the present invention can be used to accurately evaluate the leak rate and pressure change law of sealed devices. The test results prove that the method of the present invention solves the problem of leak rate change law, leakage residual pressure and low-pressure discharge safety and reliability evaluation when gas-sealed high-power thyristors are used in a vacuum environment.
[0100] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.
Claims
1. A method for evaluating the safety of residual pressure and low-pressure discharge of thyristors under vacuum conditions, characterized in that: The following steps are involved: S1. Test the leakage rate of the gas originally sealed in the thyristor; S2. Determine the relationship between the thyristor test leakage rate and leakage time, and obtain the coefficient n; S3. Determine the relationship between the change of the gas pressure P(t) inside the thyristor and time according to the relationship between the change of the thyristor test leakage rate and the leakage time and the coefficient n; S4. Calculate the service life T according to the relationship between the pressure P(t) inside the thyristor and time. life The residual pressure of internal leakage of the lower thyristor P(T life ); S5. Determine the safety of thyristor low-pressure discharge: The lower pressure threshold at which low-voltage discharge does not occur inside the thyristor is defined as P; If P(T life ) < P, then the thyristor under the service life T life has the risk problem of low-pressure discharge caused by air leakage; If P(T life )≥P, then the useful life is T life The thyristors under test can be used safely without the risk of low-pressure discharge due to gas leakage, and the safety assessment of gas leakage residual pressure and low-pressure discharge is completed.
2. The method for evaluating the safety of residual pressure and low-pressure discharge of thyristors under vacuum environment according to claim 1, characterized in that: When the thyristor can be used safely and there is no risk of low-pressure discharge due to leakage, it also includes: S6. Determine the maximum safe life of the thyristor.
3. The method for evaluating the safety of residual pressure and low-pressure discharge of thyristors under vacuum environment according to claim 2, characterized in that: Step S1 is specifically as follows: 1.
1. Define the internal pressure and volume of the gas sealed in the internal cavity of the gas-sealed thyristor at room temperature and atmosphere as P0 and ΔV respectively; P0=m×1.01×10 5 By Where m represents the number of atmospheric pressures, m≥1; 1.
2. Place the thyristor with internal pressure P0 into the helium tank for T0 time, and keep the helium pressure in the helium tank at P0+m×1.01×10 5 Pa; said 5≤T0<10; 1.
3. Take out the thyristor from the helium tank and put it into the vacuum tank of the helium mass spectrometer leak rate tester. After standing for T0 time, read the thyristor test leak rate Q1 detected by the helium mass spectrometer leak rate tester. If the thyristor test leakage rate Q1≤1×10 -7 Pa·m 3 / s, then execute step 1.4; otherwise, the thyristor leakage rate does not meet the standard, and does not have the safety of low-pressure discharge and leakage life assessment value in a vacuum environment; 1.
4. Take out the thyristor from the vacuum tank of the helium mass spectrometer leak rate tester and place it at room temperature for at least 12 hours; 1.
5. Put the thyristor back into the helium tank and let it stand for T0 time, and keep the helium pressure in the helium tank at P0+(m+1)×1.01×10 5 Pa; 1.
6. Take out the thyristor from the helium tank and put it into the vacuum tank of the helium mass spectrometer leak rate tester. After standing for T0 time, read the thyristor test leak rate Q2 detected by the helium mass spectrometer leak rate tester.
4. The method for evaluating the safety of residual pressure and low-pressure discharge of thyristors under vacuum environment according to claim 3 is characterized in that: Step S2 is specifically as follows: 2.
1. Define the atomic weight of the gas sealed in the thyristor cavity as M and the atomic weight of helium as M He The external environment pressure when the thyristor is stored or working is P E , P E ≤P0; According to the thyristor test leakage rates Q1 and Q2, the relationship between the leakage rate Q(t) of the thyristor internal pressure P0 at the time of leakage t and the leakage time t is: Where, P(t) is the internal pressure of the thyristor at the time when P0 leaks; 2.
2. The coefficient n can be obtained from the relationship between the leakage rate Q(t) and the leakage time t:
5. The method for evaluating the safety of residual pressure and low-pressure discharge of thyristors under vacuum environment according to claim 4, characterized in that: Step S3 is specifically as follows: According to the relationship between the leakage rate of the thyristor test and the leakage time and the coefficient n, the pressure P(t) inside the thyristor is determined at the external environment pressure P E The relationship between the leakage time and the leakage time t is:
6. The method for evaluating the safety of residual pressure and low-pressure discharge of thyristors under vacuum environment according to claim 5, characterized in that: Step S4 is specifically as follows: Define the thyristor under external ambient pressure P E The validity period is T life , according to the pressure P(t) inside the thyristor under the external ambient pressure P E The following relationship between the leakage time t and the service life T can be obtained by the following formula life The residual pressure of the internal leakage of the rear thyristor P(T life ); 7. The method for evaluating the safety of residual pressure and low-pressure discharge of thyristors under vacuum environment according to claim 6, characterized in that: Step S6 is specifically as follows: Defined by the external ambient pressure P E When the thyristor can be used safely without the risk of low-pressure discharge due to gas leakage, the maximum life T is calculated by the following formula: max ; 8. The method for evaluating the safety of residual pressure and low-pressure discharge of thyristors under vacuum environment according to claim 7, characterized in that: In step 1.1, m=1; In step 1.2, T0=5.
9. The method for evaluating the safety of residual pressure and low-pressure discharge of thyristors under vacuum environment according to claim 8, characterized in that: In steps 1.3 and 1.6, the vacuum degree in the vacuum tank is less than or equal to 5×10 -3 Pa.
10. The method for evaluating the safety of residual pressure and low-pressure discharge of thyristors under vacuum environment according to claim 9, characterized in that: In step S5, the value of P is 10 kPa.