Intelligent test tool and test method for inrush current

Abstract

The application discloses a kind of intelligent test tool and test method of inrush current, and the intelligent test tool includes AC input module, pre-charge bypass module, rectifier module, power module, boost loop module, sampling module and interface module, pre-charge bypass module is used to limit the pre-charging of bus capacitor and provide short-circuit bypass after pre-charging is completed, rectifier module is used to convert AC into pulsating DC voltage, power module is used to convert AC input into required DC power respectively, boost loop module is used to simulate the inrush current generated by actual circuit, sampling module respectively real-time acquisition various current voltage signals, interface module is used for signal transmission and instruction reception with external control unit.The application provides a dedicated hardware carrier for SBD maximum inrush current test through standardized hardware module, and can work with external control unit, realize accurate and efficient intelligent test.

Description

Technical Field

[0001] This invention relates to the field of testing fixture technology, and in particular to an intelligent testing fixture and method for surge current. Background Technology

[0002] Current engineering testing includes surge testing of the power grid, but there is no separate testing for the surge current generated by the device itself during operation. In particular, with the widespread use of SiC (silicon carbide), boost diodes are easily damaged in engineering, mostly due to insufficient withstand current. It is impossible to effectively detect the magnitude of the surge current generated by the module during operation, and under what conditions it is at its maximum. To address these problems and deficiencies, this paper proposes an intelligent surge current testing fixture and method to perform self-simulation testing of boost diodes within the adapter device. Summary of the Invention

[0003] One of the objectives of this invention is to provide an intelligent testing fixture and method for surge current, so as to solve the problems of poor structural compatibility, low safety and inability to adapt to automated control of existing surge testing fixtures.

[0004] The present invention provides an intelligent testing fixture for surge current, comprising: The AC input module is used to connect to an AC power source and provides filtering, overload, and short-circuit protection. A pre-charge bypass module is electrically connected to the AC input module. The pre-charge bypass module is used to perform current-limited pre-charge of the bus capacitor and to provide a short-circuit bypass after the pre-charge is completed. It includes a parallel PTC current-limiting resistor and a PTC bypass relay. A rectifier module, which is electrically connected to the precharge bypass module, is used to convert alternating current into pulsating direct current voltage; The power module, which is electrically connected to the pre-charge bypass module, is used to convert the AC input into the required DC power and to provide overvoltage and overcurrent protection. A boost circuit module, which is electrically connected to the rectifier module and the power supply module respectively, is used to simulate the surge current generated by the actual circuit; The sampling module is electrically connected to the rectifier module, the power supply module, and the boost circuit module, respectively. The sampling module collects the pulsating DC voltage signal of the rectifier module, the surge current signal of the boost circuit module, and the bus voltage signal in real time. The interface module is electrically connected to the precharge bypass module, the power supply module, and the sampling module, respectively, and is used to transmit signals and receive commands with an external control unit.

[0005] Preferably, the boost circuit module includes a boost inductor L, a PFC-IGBT, a mounting base for the SBD under test, and a bus capacitor; the boost inductor L is a high-permeability power inductor for storing electrical energy; the PFC-IGBT has a parallel FRD, which is used to control the timing of energy storage and release of the boost inductor L; the SBD under test is detachably electrically connected to the mounting base of the SBD under test; the bus capacitor is a high-voltage, large-capacity electrolytic capacitor, which is used to stabilize the bus voltage.

[0006] Preferably, heat sinks are provided on the boost inductor L, the PFC-IGBT, and the SBD mounting bracket under test.

[0007] Preferably, an insulating protective cover is provided around the SBD mounting base under test.

[0008] Preferably, the sampling module includes a current sampling unit, a bus voltage sampling unit, and a pulsating voltage sampling unit; the current sampling unit is connected in series to the branch of the SBD mounting base under test; the bus voltage sampling unit is connected in parallel to both ends of the bus capacitor; and the pulsating voltage sampling unit is connected to the output terminal of the rectifier module.

[0009] Preferably, the AC input module includes an air switch and an EMI filter circuit.

[0010] Preferably, the PTC current-limiting resistor is a positive temperature coefficient resistor; the PTC bypass relay is a high-current magnetic protection relay.

[0011] Preferably, the rectifier module uses a full-bridge rectifier circuit, and its output terminal is equipped with a filter capacitor.

[0012] Preferably, the interface module includes a control signal interface, a sampling signal interface, and a power interface.

[0013] This invention provides a surge current testing method, applied to any of the intelligent testing fixtures described above, comprising the following steps: S1, the SBD under test and the external control unit are electrically connected to the boost circuit module and the interface module respectively, and the AC power is turned on. The power supply module provides power to the boost circuit module, the sampling module and the interface module respectively. S2, AC power is sequentially connected to the rectifier module via the AC input module and the pre-charge bypass module and converted into pulsating DC voltage; S3, the PTC current-limiting resistor performs current-limiting charging of the bus capacitor in the boost circuit module, and the sampling module collects the bus voltage and pulsating voltage signals in real time and transmits them to the external control unit; S4, when the external control unit determines that the bus voltage is stable at a preset value, it sends a command to control the PTC bypass relay to engage and the PTC current limiting resistor to be shorted. S5, when the external control unit detects the pulsating voltage peak, it sends a command to control the PFC-IGBT in the boost circuit module to turn off, so that the energy stored in the boost inductor L is released to the bus capacitor through the measured SBD, generating a surge current; S6, the sampling module collects the surge current signal and transmits it to the external control unit, where the external control unit performs peak latching and data processing; S7. After the test is completed, the external control unit sends a command to control the PTC bypass relay to disconnect, the bus capacitor to discharge to 0V, and the test circuit to reset.

[0014] Compared with the prior art, the beneficial effects of the intelligent testing fixture and method for surge current of the present invention are as follows: This invention provides an intelligent surge current testing fixture and method. By incorporating comprehensive overload, overvoltage, overcurrent, and insulation protection mechanisms, along with a heat dissipation structure, it avoids device damage and electric shock risks during testing, thereby improving the reliability and safety of the testing fixture. The SBD mounting base is replaceable, adaptable to SBDs of different specifications and packages. Each module has standardized interfaces, allowing it to work collaboratively with different types of control units, thus broadening its applicability. The sampling module employs a high-precision, isolated design to reduce signal interference and ensure accurate current and voltage signals, providing reliable hardware support for SBD surge current testing. Connecting to an external control unit via standardized interfaces allows for receiving control commands and transmitting sampling signals, automating the testing process and significantly improving testing efficiency. The compact layout of modules shortens the current path, reduces line losses, and ensures the true amplitude of the surge current. It also facilitates miniaturization and mass production of the fixture, effectively solving the problems of poor structural compatibility, low safety, and inability to adapt to automated control in existing surge testing fixtures. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the electrical connection structure of an intelligent surge current testing fixture of the present invention, including a pre-charge and bypass module, a rectifier module and a boost circuit module; Figure 2 yesFigure 1 The circuit diagram of the precharge and bypass module, rectifier module and boost circuit module is shown. Figure 3 This is a flowchart illustrating a surge current testing method according to the present invention.

[0017] The diagram shows: 10, intelligent test fixture; 11, AC input module; 12, pre-charge bypass module; 13, rectifier module; 14, power supply module; 15, boost circuit module; 16, sampling module; 17, interface module; 20, external control unit. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] Please see Figure 1 and Figure 2As shown, the intelligent surge current testing fixture 10 of the present invention mainly includes an AC input module 11, a pre-charge bypass module 12, a rectifier module 13, a power supply module 14, a boost circuit module 15, a sampling module 16, and an interface module 17. The AC input module 11 is used to connect to the power frequency AC power, which provides input power to the intelligent testing fixture 10. The pre-charge bypass module 12 is electrically connected to the AC input module 11, and is used to perform current-limited pre-charge of the bus capacitor in the boost circuit module 15 and to provide a short-circuit bypass after pre-charge. The rectifier module 13 and the power supply module 14 are respectively electrically connected to the pre-charge bypass module 12. The rectifier module 13 is used to convert the AC input into a pulsating DC voltage, and the power supply module 14... The sampling module 16 is used to convert AC input into DC power required by the boost circuit module 15 and the sampling module 16, respectively. The boost circuit module 15 is electrically connected to the rectifier module 13 and the power supply module 14, respectively. The rectifier module 13 provides a stable input signal to the boost circuit module 15, and the power supply module 14 provides DC power to the boost circuit module 15. The sampling module 16 is electrically connected to the rectifier module 13, the power supply module 14 and the boost circuit module 15, respectively. The sampling module 16 collects the pulsating DC voltage signal of the rectifier module 13, the surge current signal of the boost circuit module 15 and the bus voltage signal in real time, respectively. The power supply module 14 provides DC power to the sampling module 16. The interface module 17 is electrically connected to the precharge bypass module 12, the power supply module 14 and the sampling module 16, respectively. The interface module 17 provides the external control unit 20 with a control signal interface, a sampling signal interface and a power interface.

[0021] Please see Figure 1 and Figure 2As shown, in this embodiment, the AC input module 11 includes an air switch and an EMI filter circuit. The air switch is used to provide overload and short-circuit protection for the intelligent test fixture 10, and the EMI filter circuit is used to suppress interference from the power grid, thereby ensuring the stability of the input AC power and protecting each module of the intelligent test fixture 10 from interference damage. In this embodiment, the pre-charge bypass module 12 includes a PTC current-limiting resistor and a PTC bypass relay connected in parallel. The PTC current-limiting resistor is a positive temperature coefficient resistor, which is used to limit the current of the bus capacitor in the boost circuit module 15 to prevent the initial charging current from being too large and damaging the bus capacitor. The PTC bypass relay is a high-current magnetic protection relay, which is used to short-circuit the PTC current-limiting resistor after pre-charging to provide a low-impedance path for the surge current, thereby ensuring the true amplitude of the surge current. Specifically, the PTC current-limiting resistor and the PTC bypass relay are closely arranged to shorten the current path and reduce line losses, thereby ensuring the current transmission efficiency during bypass. A freewheeling diode is connected in parallel across the two ends of the PTC bypass relay to prevent the spike voltage generated when the PTC bypass relay is engaged and disengaged from damaging other devices. In this embodiment, the rectifier module 13 adopts a full-bridge rectifier circuit, which uses a high-voltage, large-circuit rectifier chip to convert AC input into pulsating DC voltage, thereby providing a stable input signal for the boost circuit module 15; preferably, the output terminal of the rectifier module 13 is provided with a filter capacitor to reduce voltage ripple.

[0022] Please see Figure 1 As shown, in this embodiment, the power supply module 14 is an AC-DC power supply module, which is used to convert the AC input into DC power (such as 3.3V / 5V / 12V) required by the boost circuit module 15, the sampling module 16, and the interface module 17, respectively, so as to provide stable and reliable power supply to the boost circuit module 15, the sampling module 16, and the interface module 17 respectively; preferably, the power supply module 14 is provided with overvoltage and overcurrent protection circuits to prevent abnormal power supply from damaging the intelligent test fixture 10.

[0023] Please see Figure 1 and Figure 2As shown, in this embodiment, the boost circuit module 15 includes a boost inductor L, a PFC-IGBT (Power Factor Correction-Insulated Gate Bipolar Transistor), a mounting bracket for the SBD under test, and a bus capacitor. The boost inductor L is a high-permeability power inductor used to store electrical energy. The PFC-IGBT has a parallel FRD (Fast Recovery Diode) used to control the timing of energy storage and release in the boost inductor L. The mounting bracket for the SBD under test is a replaceable structure, which can be adapted to SBDs with different packages and specifications, facilitating batch testing. The bus capacitor is a high-voltage, high-capacity electrolytic capacitor used to stabilize the bus voltage and ensure the stability of the pre-charge voltage. Specifically, the boost inductor L, PFC-IGBT, and SBD mounting bracket are all equipped with heat sinks made of aluminum alloy with thermal patterns on their surface. This improves heat dissipation performance and prevents overheating of the boost inductor L, PFC-IGBT, and SBD mounting bracket during testing, thus ensuring the continuity and stability of the test. The SBD mounting bracket adopts a pluggable structure with flexible contact terminals, ensuring a reliable electrical connection between the SBD and the mounting bracket. It also allows for quick replacement of SBD devices with different packages and specifications, thereby improving the testing efficiency of the SBD. Preferably, an insulating protective cover is provided around the SBD mounting bracket to avoid the risk of high-voltage electric shock during testing.

[0024] Please see Figure 1 As shown, in this embodiment, the sampling module 16 includes a current sampling unit, a bus voltage sampling unit, and a pulsating voltage sampling unit. The current sampling unit uses a high-precision shunt, which is connected in series to the branch of the SBD mounting base under test, for acquiring surge current signals. The bus voltage sampling unit uses a differential voltage sensor, which is connected in parallel to both ends of the bus capacitor, for acquiring bus voltage signals. The pulsating voltage sampling unit uses a high-speed voltage sensor, which is electrically connected to the output of the rectifier module 13, for acquiring the pulsating DC voltage signal at the output of the rectifier module 13. Specifically, the current sampling unit, the bus voltage sampling unit, and the pulsating voltage sampling unit all adopt an isolated design to achieve electrical isolation from the boost circuit module 15, avoiding high-voltage signal interference with sampling accuracy, and protecting the external control unit 20 from high-voltage surges. Preferably, the output of the sampling module 16 is provided with a standardized signal interface for transmitting the acquired signals to the external control unit 20.

[0025] Please see Figure 1As shown, in this embodiment, the interface module 17 includes a control signal interface, a sampling signal interface, and a power interface. The control signal interface is used to receive control commands from the external control unit 20 to activate the PTC bypass relay and deactivate the PFC-IGBT. The sampling signal interface is used to transmit the current and voltage signals collected by the sampling module 16 to the external control unit 20. The power interface is used to provide stable power supply to the external control unit 20.

[0026] This invention provides a method for testing surge current, comprising the following steps: S1, connect the SBD under test and the external control unit 20 to the boost circuit module 15 and the interface module 17 respectively, turn on the AC power, and the power supply module 14 provides power to the boost circuit module 15, the sampling module 16, and the interface module 17 respectively; S2, AC power is sequentially connected to rectifier module 13 via AC input module 11 and precharge bypass module 12 and converted into pulsating DC voltage; S3, the PTC current-limiting resistor in the pre-charge and bypass module 12 performs current-limited charging of the bus capacitor in the boost circuit module 15, and the sampling module 16 collects the bus voltage and pulsating voltage signals in real time and transmits them to the external control unit 20. S4, when the external control unit 20 determines that the bus voltage is stable at the preset value, it sends a command to control the PTC bypass relay in the pre-charge and bypass module 12 to engage and short-circuit the PTC current limiting resistor. S5, when the external control unit 20 detects the pulsating voltage peak, it sends a command to control the PFC-IGBT in the boost circuit module 15 to turn off, so that the energy stored in the boost inductor L is released to the bus capacitor through the measured SBD, generating a surge current. S6, the sampling module 16 collects the surge current signal and transmits it to the external control unit 20, which then performs peak latching and data processing. S7. After the test is completed, the external control unit 20 sends a command to control the PTC bypass relay to disconnect, the bus capacitor to discharge to 0V, and the test circuit to be reset.

[0027] This invention discloses an intelligent surge current testing fixture and method. It primarily uses an external control unit 20 and a sampling module 16 to detect bus voltage and peak current. In practical applications, it can simulate the maximum surge current that a boost diode can withstand during operation or abnormal startup, preventing board failure and providing more reliable testing for engineering selection. This intelligent surge current testing fixture is not limited to BOSST PFC circuits; it can be used for other similar circuits to detect surge currents, including those occurring during capacitor charging. This avoids serious consequences and significant economic losses caused by improper matching in engineering projects.

[0028] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0029] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A smart testing fixture for surge current, characterized in that, include: The AC input module is used to connect to an AC power source and provides filtering, overload, and short-circuit protection. A pre-charge bypass module is electrically connected to the AC input module. The pre-charge bypass module is used to perform current-limited pre-charge of the bus capacitor and to provide a short-circuit bypass after the pre-charge is completed. It includes a parallel PTC current-limiting resistor and a PTC bypass relay. A rectifier module, which is electrically connected to the precharge bypass module, is used to convert alternating current into pulsating direct current voltage; The power module, which is electrically connected to the pre-charge bypass module, is used to convert the AC input into the required DC power and to provide overvoltage and overcurrent protection. A boost circuit module, which is electrically connected to the rectifier module and the power supply module respectively, is used to simulate the surge current generated by the actual circuit; The sampling module is electrically connected to the rectifier module, the power supply module, and the boost circuit module, respectively. The sampling module collects the pulsating DC voltage signal of the rectifier module, the surge current signal of the boost circuit module, and the bus voltage signal in real time. The interface module is electrically connected to the precharge bypass module, the power supply module, and the sampling module, respectively, and is used to transmit signals and receive commands with an external control unit.

2. The intelligent surge current testing fixture according to claim 1, characterized in that, The boost circuit module includes a boost inductor L, a PFC-IGBT, a mounting base for the SBD under test, and a bus capacitor. The boost inductor L is a high-permeability power inductor used for storing electrical energy. The PFC-IGBT has a parallel FRD, which is used to control the timing of energy storage and release of the boost inductor L. The SBD under test is detachably electrically connected to the mounting base. The bus capacitor is a high-voltage, high-capacity electrolytic capacitor used to stabilize the bus voltage.

3. The intelligent testing fixture for surge current according to claim 2, characterized in that, Heat sinks are provided on the boost inductor L, the PFC-IGBT, and the SBD under test mounting base.

4. The intelligent surge current testing fixture according to claim 2, characterized in that, An insulating protective cover is provided around the SBD mounting base under test.

5. The intelligent testing fixture for surge current according to claim 2, characterized in that, The sampling module includes a current sampling unit, a bus voltage sampling unit, and a pulsating voltage sampling unit; the current sampling unit is connected in series to the branch of the SBD mounting base under test; the bus voltage sampling unit is connected in parallel to both ends of the bus capacitor; and the pulsating voltage sampling unit is connected to the output terminal of the rectifier module.

6. The intelligent surge current testing fixture according to claim 1, characterized in that, The AC input module includes an air switch and an EMI filter circuit.

7. The intelligent surge current testing fixture according to claim 1, characterized in that, The PTC current-limiting resistor is a positive temperature coefficient resistor; the PTC bypass relay is a high-current magnetic protection relay.

8. The intelligent testing fixture for surge current according to claim 1, characterized in that, The rectifier module uses a full-bridge rectifier circuit, and its output terminal is equipped with a filter capacitor.

9. The intelligent testing fixture for surge current according to claim 1, characterized in that, The interface module includes a control signal interface, a sampling signal interface, and a power interface.

10. A method for testing surge current, applied in the intelligent testing fixture described in any one of claims 1-9, characterized in that, Includes the following steps: S1, the SBD under test and the external control unit are electrically connected to the boost circuit module and the interface module respectively, and the AC power is turned on. The power supply module provides power to the boost circuit module, the sampling module and the interface module respectively. S2, AC power is sequentially connected to the rectifier module via the AC input module and the pre-charge bypass module and converted into pulsating DC voltage; S3, the PTC current-limiting resistor performs current-limiting charging of the bus capacitor in the boost circuit module, and the sampling module collects the bus voltage and pulsating voltage signals in real time and transmits them to the external control unit; S4, when the external control unit determines that the bus voltage is stable at a preset value, it sends a command to control the PTC bypass relay to engage and the PTC current limiting resistor to be shorted. S5, when the external control unit detects the pulsating voltage peak, it sends a command to control the PFC-IGBT in the boost circuit module to turn off, so that the energy stored in the boost inductor L is released to the bus capacitor through the measured SBD, generating a surge current; S6, the sampling module collects the surge current signal and transmits it to the external control unit, where the external control unit performs peak latching and data processing; S7. After the test is completed, the external control unit sends a command to control the PTC bypass relay to disconnect, the bus capacitor to discharge to 0V, and the test circuit to reset.

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