Method and circuit for testing overcurrent protection threshold and PCB (printed circuit board)

Abstract

The invention discloses an over-current protection threshold test method, a test circuit and a PCB, and the method comprises the steps: selecting a plurality of temperatures from a preset working temperature range as to-be-tested temperatures, and selecting any to-be-tested temperature for testing; controlling the intelligent power module to start working and transmitting a pulse signal to the intelligent power module; when the voltage of the PFC protection end is gradually increased or gradually reduced, if the real-time current value of the IGBT unit is suddenly changed, acquiring the real-time voltage of the PFC protection end at the suddenly changed moment as a to-be-verified turn-off threshold value or a to-be-verified reset threshold value; judging whether the turn-off threshold to be verified and the reset threshold to be verified are in a preset standard range or not; if yes, selecting another to-be-tested temperature for testing, and returning to execute the operation of controlling the intelligent power module to start working; according to the test method disclosed by the invention, whether the overcurrent protection function of the intelligent power module is normal or not can be verified under different temperature conditions, so that products with unqualified overcurrent protection turn-off thresholds and reset thresholds are prevented from flowing into the market.

Description

Technical Field

[0001] The present invention relates to the technical field of overcurrent testing, and in particular to a testing method, a testing circuit and a PCB board for an overcurrent protection threshold. Background Art

[0002] Intelligent power module, referred to as IPM, is a power drive product that combines power electronics technology with integrated circuit technology. It integrates power switching devices and high-voltage drive circuits, and has built-in fault detection functions such as overvoltage, overcurrent and overheating. The intelligent power module can not only receive control signals from the microcontroller to drive subsequent circuits, but also feed back detection signals of the system status to the MCU. Compared with traditional discrete solutions, IPM has won a growing market share with its high integration and high reliability. It is particularly suitable for motor drives of frequency converters and various inverter power supplies. It is an ideal power electronic component for variable frequency speed regulation, metallurgical machinery, electric traction, servo drive and variable frequency home appliances.

[0003] With the rapid development of industry, IPM intelligent power modules have been widely used in many fields. In IPM intelligent power modules, overcurrent protection function is very important. For example, in the IPM of three-phase full-bridge plus PFC circuit, if the PFC circuit has overcurrent, that is, the current value flowing through the IGBT exceeds the set overcurrent action current and lasts for more than toff, then the overcurrent protection mechanism will be triggered, the gate drive circuit will be blocked, and a fault signal will be output; similarly, if the load is short-circuited or the control system fails and causes a short circuit, and the current value flowing through the IGBT exceeds the short-circuit action current, the system will immediately perform short-circuit protection, block the gate drive circuit, and output a fault signal.

[0004] Therefore, when the IPM intelligent power module is produced, its PFC circuit overcurrent protection threshold voltage must be tested to see if it meets the standard. However, in current production workshops, there is a lack of detection of the overcurrent protection threshold voltage when the product is produced. It can be seen that the existing technology still needs to be improved and enhanced. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a testing method for overcurrent protection threshold, which can verify whether the overcurrent protection function of the intelligent power module is normal under different temperature conditions, so as to prevent products with unqualified overcurrent protection shutdown threshold and reset threshold from entering the market.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for testing an overcurrent protection threshold comprises: selecting a plurality of temperatures from an operating temperature range of an intelligent power module as temperatures to be tested, and adjusting a test environment of the intelligent power module to any temperature to be tested; controlling the intelligent power module to start working, and transmitting a pulse signal to a PFC input terminal and a PFC protection terminal of the intelligent power module; when the voltage at the PFC protection terminal gradually increases, if the real-time current value of an IGBT unit of the intelligent power module suddenly changes, obtaining the real-time voltage of the PFC protection terminal at the moment of sudden change as a shutdown threshold to be verified; when the voltage at the PFC protection terminal gradually decreases, if the real-time current value of the IGBT unit of the intelligent power module suddenly changes, obtaining the real-time voltage of the PFC protection terminal at the moment of sudden change as a reset threshold to be verified; judging whether the shutdown threshold to be verified and the reset threshold to be verified are within a preset standard range, and if not, outputting product unqualified information; if yes, adjusting the test environment of the intelligent power module to another temperature to be tested, and returning to execute control of the intelligent power module to start working.

[0008] In the test method of the overcurrent protection threshold, multiple temperatures are selected from the operating temperature range of the intelligent power module as the temperatures to be tested, and the test environment of the intelligent power module is adjusted to any temperature to be tested, including: obtaining the operating temperature range of the intelligent power module; selecting the starting point, the end point and one or more intermediate points of the operating temperature range as the temperatures to be tested from the acquired operating temperature range; sorting the multiple temperatures to be tested from low to high according to the temperature, and according to the sorting result, first adjusting the operating temperature of the temperature control box in the test environment to the lowest value of the temperature to be tested.

[0009] In the test method of the overcurrent protection threshold, the control of the intelligent power module to start working and transmit pulse signals to the PFC input terminal and the PFC protection terminal of the intelligent power module includes: controlling the first DC power supply to provide a 15V working voltage to the VCC terminal of the intelligent power module, and controlling the second DC power supply to provide a 5V working voltage to the FLTEN terminal of the intelligent power module, so that the intelligent power module starts working; controlling the first signal generator to transmit a pulse signal to the PFCIN terminal of the intelligent power module, and controlling the second signal generator to transmit a pulse signal to the PFCTRIP terminal of the intelligent power module, so that the real-time voltage of the PFCTRIP terminal of the intelligent power module gradually increases or decreases within the rated voltage range.

[0010] In the test method of the overcurrent protection threshold, when the voltage at the PFC protection end gradually increases, if the real-time current value of the IGBT unit of the intelligent power module is less than the preset minimum operating current, the real-time current value suddenly changes; when the voltage at the PFC protection end gradually increases, if the real-time current value of the IGBT unit of the intelligent power module is greater than the preset maximum operating current, the real-time current value suddenly changes.

[0011] In the test method for the overcurrent protection threshold, the determination of whether the shutdown threshold to be checked and the reset threshold to be checked are within a preset standard range, and if not, outputting product unqualified information includes: obtaining a preset standard range, and the preset standard range includes a shutdown upper limit value, a shutdown lower limit value, a reset upper limit value, and a reset lower limit value; determining whether the shutdown threshold to be checked is greater than or equal to the shutdown lower limit value and less than or equal to the shutdown upper limit value, and determining whether the reset threshold to be checked is greater than or equal to the reset lower limit value and less than or equal to the reset upper limit value, and if any one of them is not, outputting product unqualified information.

[0012] In the test method for the overcurrent protection threshold, the preset standard range includes the shutdown standard threshold, the reset standard threshold, the shutdown allowable error value and the reset allowable error; the shutdown upper limit value is equal to the shutdown standard threshold + the shutdown allowable error value, and the shutdown lower limit value is equal to the shutdown standard threshold - the shutdown allowable error value; the reset upper limit value is equal to the reset standard threshold + the reset allowable error value, and the reset lower limit value is equal to the reset standard threshold - the reset allowable error value.

[0013] The present invention also correspondingly provides a test circuit for an overcurrent protection threshold, the test circuit is used to implement any of the test methods described above, the test circuit includes an intelligent power module, a DC power supply unit, a pulse signal generating unit, a voltage detection unit and a current detection unit, the intelligent power module includes an IGBT unit; the output end of the DC power supply unit is respectively connected to the VCC end and the FLTEN end of the intelligent power module, the output end of the pulse signal generating unit is respectively connected to the PFCIN end and the PFCTRIP end of the intelligent power module, the voltage detection unit is used to obtain the real-time voltage of the PFCTRIP end, and the current detection unit is used to obtain the real-time current of the IGBT unit.

[0014] In the test circuit of the overcurrent protection threshold, the DC power supply unit includes a first DC power supply and a second DC power supply; the first DC power supply is connected to the VCC terminal and is used to provide a 15V DC voltage to the VCC terminal; the second DC power supply is connected to the FLTEN terminal through a first resistor R1 and is used to provide a 5V DC voltage to the FLTEN terminal.

[0015] In the test circuit of the overcurrent protection threshold, the current detection unit includes a third DC power supply and an ammeter, the third DC power supply provides a working voltage for the ammeter, and the ammeter is used to obtain the real-time current of the IGBT unit.

[0016] The present invention also provides a PCB board accordingly, characterized in that a test circuit for the overcurrent protection threshold as described in any one of the above items is printed on the PCB board.

[0017] Beneficial effects:

[0018] The present invention provides a method for testing an overcurrent protection threshold. By selecting a plurality of different temperatures to be tested within an operating temperature range, it is possible to verify whether the overcurrent protection function of an intelligent power module is normal under different temperature conditions, thereby ensuring that the shutdown threshold to be tested and the reset threshold to be verified are both within a preset standard range, so as to prevent products with unqualified overcurrent protection shutdown threshold and reset threshold from entering the market, thereby improving product reliability and safety, ensuring that the intelligent power module can accurately respond to overcurrent protection in actual applications, and avoiding equipment damage or safety accidents caused by overcurrent. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A logic flow chart of the test method provided by the present invention;

[0020] Figure 2 A circuit structure diagram of a test circuit provided by the present invention;

[0021] Figure 3 This is a test timing diagram of the intelligent power module provided by the present invention.

[0022] Description of main component symbols: 11 - first DC power supply, 12 - second DC power supply, 21 - first signal generator, 22 - second signal generator, 31 - third DC power supply, 32 - ammeter. DETAILED DESCRIPTION

[0023] The present invention provides a test method, a test circuit and a PCB board for an overcurrent protection threshold. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples.

[0024] In the description of the present invention, it should be understood that the terms "installation", "connection" and the like should be understood in a broad sense, and a person skilled in the art can understand the specific meanings of the above terms in the present invention according to specific circumstances.

[0025] See also Figures 1 to 3 The present invention provides a method for testing an overcurrent protection threshold, comprising:

[0026] 100. Select multiple temperatures from the operating temperature range of the intelligent power module as the temperatures to be measured, and adjust the test environment of the intelligent power module to any temperature to be measured;

[0027] 200. Control the intelligent power module to start working, and transmit a pulse signal to the PFC input terminal and the PFC protection terminal of the intelligent power module;

[0028] 300. When the voltage at the PFC protection terminal gradually increases, if the real-time current value of the IGBT unit of the intelligent power module changes suddenly, the real-time voltage at the PFC protection terminal at the moment of the sudden change is obtained as the shutdown threshold to be verified;

[0029] In this embodiment, when the voltage at the PFC protection end gradually increases, if the real-time current value of the IGBT unit of the intelligent power module is less than the preset minimum operating current, a sudden change in the real-time current value will occur. The minimum operating current is 0.1 mA, which is related to the design parameters of the intelligent power module.

[0030] 400. When the voltage of the PFC protection terminal gradually decreases, if the real-time current value of the IGBT unit of the intelligent power module changes suddenly, the real-time voltage of the PFC protection terminal at the moment of the sudden change is obtained as the reset threshold to be verified;

[0031] In this embodiment, when the voltage at the PFC protection end gradually increases, if the real-time current value of the IGBT unit of the intelligent power module is greater than the preset maximum operating current, a sudden change in the real-time current value will occur. The maximum operating current is 0.9 mA, which is related to the design parameters of the intelligent power module.

[0032] In this embodiment, the real-time voltage is obtained through an oscilloscope, that is, the shutdown threshold to be verified and the reset threshold to be verified are obtained through the oscilloscope.

[0033] 500. Determine whether the shutdown threshold to be verified and the reset threshold to be verified are within a preset standard range. If not, output product unqualified information; if yes, adjust the test environment of the intelligent power module to another temperature to be tested, and return to execute control of the intelligent power module to start working;

[0034] In this embodiment, steps 100 to 500 are repeatedly executed until the selected temperatures to be measured are all tested through the overcurrent protection threshold, i.e., the overcurrent protection function of the intelligent power module is ensured to pass the test under different temperature conditions; when the test result corresponding to any temperature to be measured indicates that the product is unqualified, the product unqualified information is output, and the product qualified information is output only when the test results corresponding to all temperatures to be measured indicate that the product is qualified.

[0035] The present application discloses a method for testing an overcurrent protection threshold. By selecting a plurality of different temperatures to be tested within an operating temperature range, it is possible to verify whether the overcurrent protection function of an intelligent power module is normal under different temperature conditions, and ensure that the shutdown threshold to be tested and the reset threshold to be verified are both within a preset standard range, so as to prevent products with unqualified overcurrent protection shutdown threshold and reset threshold from entering the market, thereby improving product reliability and safety, and ensuring that the intelligent power module can accurately respond to overcurrent protection in actual applications, and avoiding equipment damage or safety accidents caused by overcurrent.

[0036] In this embodiment, step 100 specifically includes:

[0037] 101. Obtain an operating temperature range of the intelligent power module, where the operating temperature range is -40°C to 125°C;

[0038] 102. From the acquired working temperature range, select a starting point, an end point, and one or more intermediate points of the working temperature range as temperatures to be measured;

[0039] In this embodiment, since the working characteristics of the intelligent power module IPM will change to a certain extent at different temperatures, it is necessary to select multiple temperatures to be tested, and to test the overcurrent protection threshold of the intelligent power module at the test environment temperature corresponding to each temperature to be tested; specifically, the starting point, the end point and one or more key intermediate points of the operating temperature range are selected as the temperatures to be tested, which can ensure that the equipment can maintain stable performance under extreme conditions, thereby improving the reliability and durability of the product. Secondly, by testing at these key temperature points, the performance of the equipment in various temperature environments that may be encountered during actual use can be comprehensively evaluated to ensure that the product can provide stable and reliable services in various environments.

[0040] 103. Sort multiple temperatures to be tested from low to high. According to the sorting result, first adjust the working temperature of the temperature control box in the test environment to the lowest temperature to be tested.

[0041] In this embodiment, the operating temperature of the temperature control box is first adjusted to the lowest value of all temperatures to be tested, which not only lays a stable starting point for subsequent testing work, but also allows the ambient temperature to be adjusted incrementally subsequently, avoiding frequent adjustments to the temperature of the temperature control box during the test, thereby saving valuable time and resources; in addition, this orderly testing method helps to reduce errors caused by temperature fluctuations and ensures the accuracy and reliability of test data.

[0042] In this embodiment, step 200 specifically includes:

[0043] 201. Control the first DC power supply 11 to provide a 15V working voltage to the VCC terminal of the intelligent power module, and control the second DC power supply 12 to provide a 5V working voltage to the FLTEN terminal of the intelligent power module, so that the intelligent power module starts to work;

[0044] 202. Control the first signal generator 21 to transmit a pulse signal to the PFCIN terminal of the intelligent power module, and control the second signal generator 22 to transmit a pulse signal to the PFCTRIP terminal of the intelligent power module, so that the real-time voltage of the PFCTRIP terminal of the intelligent power module gradually increases or decreases within a rated voltage range;

[0045] In this embodiment, the rated voltage range is 0-5V.

[0046] In this embodiment, step 400 includes:

[0047] 401. Obtain a preset standard range, where the preset standard range includes a shutdown upper limit value, a shutdown lower limit value, a reset upper limit value, and a reset lower limit value;

[0048] In this embodiment, the preset standard range includes a shutdown standard threshold, a reset standard threshold, a shutdown allowable error value and a reset allowable error; the shutdown upper limit value is equal to the shutdown standard threshold + the shutdown allowable error value, and the shutdown lower limit value is equal to the shutdown standard threshold - the shutdown allowable error value; the reset upper limit value is equal to the reset standard threshold + the reset allowable error value, and the reset lower limit value is equal to the reset standard threshold - the reset allowable error value; the shutdown standard threshold and the reset standard threshold are related to the design parameters of the intelligent power module, the shutdown allowable error value is the shutdown standard threshold * 5%, and the reset allowable error value is the reset standard threshold * 0.5%.

[0049] 402. Determine whether the shutdown threshold to be tested is greater than or equal to the shutdown lower limit value and less than or equal to the shutdown upper limit value, and determine whether the reset threshold to be checked is greater than or equal to the reset lower limit value and less than or equal to the reset upper limit value. If any one of them is not, output product unqualified information; if both are yes, it indicates that at the temperature to be tested, the over-temperature protection function of the intelligent power module is normal, and then adjust the ambient temperature of the test environment to another temperature to be tested until the over-temperature protection test under all the temperature conditions to be tested is completed; when the over-temperature protection test under all the temperature conditions to be tested indicates that the over-temperature protection function of the intelligent power module is normal, output product qualified information.

[0050] See also Figure 2 The present invention also provides a test circuit for an overcurrent protection threshold accordingly, the test circuit is used to implement any of the test methods described above, the test circuit includes an intelligent power module, a DC power supply unit, a pulse signal generating unit, a voltage detection unit and a current detection unit, the intelligent power module includes an IGBT unit; the output end of the DC power supply unit is respectively connected to the VCC end and the FLTEN end of the intelligent power module, the output end of the pulse signal generating unit is respectively connected to the PFCIN end and the PFCTRIP end of the intelligent power module, the voltage detection unit is used to obtain the real-time voltage of the PFCTRIP end, and the current detection unit is used to obtain the real-time current of the IGBT unit.

[0051] In this embodiment, the voltage detection unit includes an oscilloscope, and the oscilloscope is connected to the PFCTRIP terminal of the intelligent power module to obtain the real-time voltage of the PFCTRIP terminal.

[0052] For further information, see Figure 2 The DC power supply unit includes a first DC power supply 11 and a second DC power supply 12; the first DC power supply 11 is connected to the VCC terminal for providing a 15V DC voltage to the VCC terminal; the second DC power supply 12 is connected to the FLTEN terminal through a first resistor R1 for providing a 5V DC voltage to the FLTEN terminal; in this embodiment, the first resistor R1 is a pull-up resistor.

[0053] For further information, see Figure 2 The current detection unit includes a third DC power supply 31 and an ammeter 32. The third DC power supply 31 provides a working voltage for the ammeter 32, and the ammeter 32 is used to obtain the real-time current of the IGBT unit. In this embodiment, the third DC power supply 31 is used to provide a 1V DC voltage to ensure that the ammeter 32 works normally and stably.

[0054] The present invention also provides a PCB board accordingly, characterized in that a test circuit for the overcurrent protection threshold as described in any one of the above items is printed on the PCB board.

[0055] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the present invention.

Claims

1. A method for testing an overcurrent protection threshold, characterized in that: include: Selecting multiple temperatures from the operating temperature range of the intelligent power module as the temperatures to be tested, and adjusting the test environment of the intelligent power module to any of the temperatures to be tested; Control the intelligent power module to start working and send pulse signals to the PFC input terminal and PFC protection terminal of the intelligent power module; When the voltage at the PFC protection terminal gradually increases, if the real-time current value of the IGBT unit of the intelligent power module changes suddenly, the real-time voltage at the PFC protection terminal at the moment of the sudden change is obtained as the shutdown threshold to be checked; When the voltage of the PFC protection terminal gradually decreases, if the real-time current value of the IGBT unit of the intelligent power module changes suddenly, the real-time voltage of the PFC protection terminal at the moment of the sudden change is obtained as the reset threshold to be checked; Determine whether the shutdown threshold to be verified and the reset threshold to be verified are within the preset standard range. If not, output product unqualified information; If yes, the test environment of the intelligent power module is adjusted to another temperature to be tested, and the execution control of the intelligent power module is returned to start working.

2. The method for testing the overcurrent protection threshold according to claim 1, characterized in that: The step of selecting a plurality of temperatures from the operating temperature range of the intelligent power module as the temperatures to be measured, and adjusting the test environment of the intelligent power module to any temperature to be measured, comprises: Get the operating temperature range of the intelligent power module; From the obtained working temperature range, select the starting point, the end point and one or more intermediate points of the working temperature range as the temperatures to be measured; The multiple temperatures to be tested are sorted from low to high according to the temperature. According to the sorting result, the working temperature of the temperature control box in the test environment is first adjusted to the temperature to be tested with the lowest value.

3. The method for testing the overcurrent protection threshold according to claim 1, characterized in that: The controlling the intelligent power module to start working and transmitting a pulse signal to the PFC input terminal and the PFC protection terminal of the intelligent power module includes: Control the first DC power supply to provide a 15V operating voltage to the VCC terminal of the intelligent power module, and control the second DC power supply to provide a 5V operating voltage to the FLTEN terminal of the intelligent power module, so that the intelligent power module starts working; The first signal generator is controlled to transmit a pulse signal to the PFCIN terminal of the intelligent power module, and the second signal generator is controlled to transmit a pulse signal to the PFCTRIP terminal of the intelligent power module, so that the real-time voltage of the PFCTRIP terminal of the intelligent power module gradually increases or decreases within the rated voltage range.

4. The method for testing the overcurrent protection threshold according to claim 1, characterized in that: When the voltage at the PFC protection end gradually increases, if the real-time current value of the IGBT unit of the intelligent power module is less than the preset minimum operating current, the real-time current value suddenly changes; when the voltage at the PFC protection end gradually increases, if the real-time current value of the IGBT unit of the intelligent power module is greater than the preset maximum operating current, the real-time current value suddenly changes.

5. The method for testing the overcurrent protection threshold according to claim 1, characterized in that: The step of judging whether the shutdown threshold to be verified and the reset threshold to be verified are within a preset standard range, and if not, outputting product unqualified information includes: Obtaining a preset standard range, wherein the preset standard range includes a shutdown upper limit value, a shutdown lower limit value, a reset upper limit value, and a reset lower limit value; Determine whether the shutdown threshold to be tested is greater than or equal to the shutdown lower limit value and less than or equal to the shutdown upper limit value, and determine whether the reset threshold to be checked is greater than or equal to the reset lower limit value and less than or equal to the reset upper limit value. If any of them is not, output product unqualified information.

6. The method for testing the overcurrent protection threshold according to claim 5, characterized in that: The preset standard range includes the shutdown standard threshold, the reset standard threshold, the shutdown allowable error value and the reset allowable error; the shutdown upper limit value is equal to the shutdown standard threshold + the shutdown allowable error value, and the shutdown lower limit value is equal to the shutdown standard threshold - the shutdown allowable error value; the reset upper limit value is equal to the reset standard threshold + the reset allowable error value, and the reset lower limit value is equal to the reset standard threshold - the reset allowable error value.

7. Overcurrent protection threshold test circuit, characterized in that: The test circuit is used to implement the test method according to any one of claims 1 to 6, the test circuit includes an intelligent power module, a DC power supply unit, a pulse signal generating unit, a voltage detection unit and a current detection unit, the intelligent power module includes an IGBT unit; the output end of the DC power supply unit is respectively connected to the VCC end and the FLTEN end of the intelligent power module, the output end of the pulse signal generating unit is respectively connected to the PFCIN end and the PFCTRIP end of the intelligent power module, the voltage detection unit is used to obtain the real-time voltage of the PFCTRIP end, and the current detection unit is used to obtain the real-time current of the IGBT unit.

8. The overcurrent protection threshold test circuit according to claim 7, characterized in that: The DC power supply unit includes a first DC power supply and a second DC power supply; the first DC power supply is connected to the VCC terminal and is used to provide a 15V DC voltage to the VCC terminal; the second DC power supply is connected to the FLTEN terminal through a first resistor R1 and is used to provide a 5V DC voltage to the FLTEN terminal.

9. The overcurrent protection threshold test circuit according to claim 7, characterized in that: The current detection unit includes a third DC power supply and an ammeter. The third DC power supply provides an operating voltage for the ammeter, and the ammeter is used to obtain the real-time current of the IGBT unit.

10. A PCB board, characterized in that: The PCB board is printed with a test circuit for the overcurrent protection threshold as described in any one of claims 7 to 9.

Images