Method and system for testing electromagnetic radiation characteristics of IGBT module for converter valve

Abstract

The invention discloses a method and system for testing electromagnetic radiation characteristics of an IGBT module for a converter valve, and the method comprises the steps: selecting an inductive load connection mode according to the position of an IGBT to be tested during testing: testing an upper IGBT, and connecting the two ends of an inductive load with a first wiring terminal and a second wiring terminal (the first wiring terminal is a neutral point between the upper IGBT and a lower IGBT) of the converter valve; and when the lower tube IGBT is tested, the first wiring terminal and the positive terminal of the bus capacitor are connected. A combined electromagnetic field probe is arranged around the IGBT to be detected, a probe shell is grounded, and a lead is connected with a signal conversion device. Firstly, a bus capacitor is charged to a stable voltage, and environmental background noise is collected by a probe when no gate pole is triggered. And pulse parameters are set by the upper computer and are sent to the driving board through the optical fiber to trigger the IGBT double-pulse action. Electric signals output by the probe are converted into optical signals through the photoelectric converter and transmitted to external equipment through the optical fiber to be restored. And subtracting background noise from a double-pulse measurement result, extracting a net radiation electromagnetic signal, and separating electromagnetic interference signals in different processes according to the switching time of the IGBT. The invention aims to accurately measure the radiation electromagnetic interference signal of the IGBT in the converter valve module in the switching-on, switching-off and diode follow current processes, and provides a basis for the electromagnetic compatibility design and shielding reinforcement of the converter valve module.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic compatibility testing and relates to a method and system for testing electromagnetic radiation characteristics of an IGBT module for a converter valve. Background Art

[0002] High-power IGBT modules are widely used in renewable energy grid-connected converters and flexible direct current transmission projects. Their high-speed switching characteristics cause sudden changes in high voltage and current, generating radiated electromagnetic interference in the near-field space. Electromagnetic interference can be transmitted through spatial coupling or cable loops into the driver board, measurement and control unit, and communication harness in the near-field space, causing false triggering, sampling drift, and even device failure. Therefore, electromagnetic interference issues must be considered at the beginning of equipment design or before deployment. In combination with currently developed non-invasive status detection, pre-measurement of the electromagnetic radiation characteristics of the IGBT module is performed to provide quantitative thresholds and model parameters for subsequent online health monitoring.

[0003] The current common open-field and semi-anechoic chamber test methods require measuring electromagnetic radiation levels at a standard distance using a far-field antenna. However, the wavelength ratio between the antenna and the device under test is too high in the low-frequency band, and the test distance is insufficient to form far-field conditions. The field strength fluctuates significantly over time and space, resulting in poor test repeatability and large deviations in results, making it insufficient to complete electromagnetic interference measurements in the near-field space of the device. A handheld near-field probe is used to obtain an electromagnetic field amplitude diagram close to the module. However, factors such as slight deflections in the probe's posture, errors in the distance between the probe and the device, and electromagnetic fields generated by external devices can lead to significant differences in results even in repeated measurements at the same workstation. In addition, the IGBT modules used in the project need to be fixed to the busbar or test inverter for operation, and the packaging forms and terminal layouts are diverse. Designing a new busbar after disassembly not only increases costs but also introduces additional parasitic parameters. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides a method and system for testing the electromagnetic radiation characteristics of an IGBT module for a converter valve. The purpose is to accurately measure the radiated electromagnetic interference signal of the IGBT in the converter valve module during the opening, closing and diode freewheeling processes, thereby providing a basis for the electromagnetic compatibility design and shielding reinforcement of the converter valve module.

[0005] In order to solve the above technical problems, the present invention is implemented through the following technical solutions:

[0006] According to a first aspect of the present invention, a method for testing electromagnetic radiation characteristics of an IGBT module for a converter valve is provided, comprising:

[0007] Select the inductive load connection method based on the position of the IGBT to be tested. If testing the top IGBT, connect the two ends of the inductive load to the first terminal and the second terminal of the converter valve, respectively. The first terminal is the neutral point between the top and bottom IGBTs. If testing the bottom IGBT, connect the two ends of the inductive load to the first terminal of the converter valve and the exposed positive terminal of the bus capacitor, respectively.

[0008] Arrange combined electromagnetic field probes around the upper and lower IGBTs to be tested. The probe housings are grounded to the converter valve body, and the leads of each probe are connected to a signal conversion device.

[0009] After charging the bus capacitor to a stable voltage, the ambient noise of the converter valve is collected using a probe in the absence of gate triggering.

[0010] The on-pulse width and off-pulse interval parameters are set by the host computer and sent to the driver board via optical fiber to trigger the IGBT to be tested to perform double pulse on-off action;

[0011] The electrical signal output by the probe is converted into an optical signal by a photoelectric converter, and then transmitted to an external device through an optical fiber and restored to an electrical signal;

[0012] Subtract the background noise from the double-pulse measurement results to extract the net radiated electromagnetic signals during the turn-on, turn-off and diode freewheeling phases of the IGBT under test.

[0013] According to the switching moment of the IGBT to be tested, the electromagnetic interference signals of the forward conduction turn-on / turn-off process and the reverse freewheeling / reverse recovery process are separated.

[0014] In a possible implementation of the first aspect, the combined electromagnetic field probe includes an electric field probe and a magnetic field probe. The electric field probe and the magnetic field probe adopt a time-sharing independent measurement mode. During the two independent measurement modes, the bus capacitor voltage, gate drive pulse width, inductive load connection method and test environment remain consistent.

[0015] In a possible implementation of the first aspect, separating the electromagnetic interference signals of the forward conduction turn-on / turn-off process and the reverse freewheeling / reverse recovery process according to the switching moment of the IGBT to be tested is specifically as follows:

[0016] When testing the top IGBT, the top probe signal corresponds to the top IGBT forward conduction turn-on / turn-off radiation; the bottom probe signal corresponds to the bottom IGBT anti-parallel diode freewheeling / reverse recovery radiation;

[0017] When testing the lower IGBT, the lower probe signal corresponds to the forward conduction turn-on / turn-off radiation of the lower IGBT; the upper probe signal corresponds to the freewheeling / reverse recovery radiation of the upper IGBT anti-parallel diode.

[0018] In a possible implementation of the first aspect, the following conditions must be met when collecting the background noise of the converter valve environment:

[0019] The gate driver board, switching power supply and all equipment complete power-on self-test.

[0020] In a possible implementation of the first aspect, the dual pulse parameters further include a bus capacitor voltage value and a number of repeated tests, which are dynamically set by a host computer;

[0021] The results of repeated tests were averaged to improve the signal-to-noise ratio.

[0022] According to a second aspect of the present invention, a system for testing electromagnetic radiation characteristics of an IGBT module for a converter valve is provided, which is used to implement the aforementioned method for testing electromagnetic radiation characteristics of an IGBT module for a converter valve, and is characterized by comprising:

[0023] The converter valve module includes a half-bridge structure of an upper IGBT and a lower IGBT connected in parallel, and provides a first terminal, a second terminal, and an exposed positive terminal of a bus capacitor. The first terminal is a neutral point between the upper IGBT and the lower IGBT.

[0024] The switchable load circuit consists of an inductive load and a current harness. By connecting the first terminal to the second terminal, or the first terminal to the exposed positive terminal of the bus capacitor, the upper IGBT / lower IGBT test mode can be switched.

[0025] A near-field probe array includes a combination of electromagnetic field probes distributed around the upper tube IGBT and the lower tube IGBT, and the probe housing is conductively connected to the valve body of the converter valve;

[0026] Photoelectric isolation transmission unit, including photoelectric converter and optical fiber, converts the probe electrical signal into optical signal for transmission, and restores the optical signal into electrical signal;

[0027] The control center includes a high-voltage DC power supply, a host computer, and an optical signal generator, and is used for bus capacitor charging, dual-pulse parameter transmission, signal processing, and background noise calibration.

[0028] In a possible implementation of the second aspect, the combined electromagnetic field probe is an integration of an electric field probe and a magnetic field probe, and each probe lead is centrally introduced into the photoelectric converter using a shielded twisted pair cable.

[0029] In a possible implementation of the second aspect, the exposed positive terminal of the bus capacitor is configured as an exposed copper busbar structure, which is used to directly connect to a current harness of an inductive load loop.

[0030] In a possible implementation of the second aspect, the host computer has a built-in noise separation algorithm that automatically divides the radiation signals in the forward conduction and reverse freewheeling stages according to the IGBT switching moment.

[0031] In a possible implementation of the second aspect, the high-voltage direct current power supply adopts a constant current charging mode, and the charging rate is dynamically controlled by a host computer.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] The present invention provides a method for testing the electromagnetic radiation characteristics of an IGBT module for a converter valve. By connecting an inductive load through the external lead-out path of the converter valve and its own port, two dual-pulse test operating modes for the upper tube IGBT and the lower tube IGBT are completed without disassembling the metal structure of the converter valve module. This method retains the true parasitic parameters of the laminated busbar, so that the dv / dt and di / dt at the moment of opening and closing are highly consistent with the on-site operating conditions, thereby ensuring that the measurement results can truly reflect the working scenario of the IGBT module in the project, and avoiding the measurement deviation caused by assembly and disassembly errors, stray parameters introduced by additional fixtures, and changes in the radiation space environment when performing far-field or darkroom scanning after the IGBT module is disassembled in the prior art. Electromagnetic field probes are respectively set on the upper tube IGBT and lower tube IGBT modules, and electromagnetic signals are collected in real time under dual-pulse excitation and the background noise is subtracted. Since the upper tube IGBT and lower tube IGBT modules only work in one of the two working modes of forward conduction and reverse freewheeling according to the time of opening and closing triggers, the working space of the power modules is relatively independent. Therefore, the electromagnetic interference radiated during the forward conduction and reverse freewheeling of the IGBT can be separately measured in the same converter valve, providing an accurate basis for subsequent electromagnetic compatibility design and shielding reinforcement. The present invention can simulate the electromagnetic radiation characteristics of the IGBT module during the switching process in the converter valve module, and realize the repeatable and quantitative measurement of the intensity and characteristics of the IGBT radiation source in the near-field space. Through the switchable load extraction method, the double pulse test of the upper tube IGBT and the lower tube IGBT in the same physical space is realized. Without disassembling the device or adding simulation accessories, the current loop in the converter valve submodule can be truly reproduced, avoiding the measurement deviation caused by the additional introduction of parasitic inductance and resistance mismatch, and ensuring the repeatability of the measurement results. At the same time, in conjunction with the transmission of the photoelectric converter, the system noise is effectively suppressed, and the electric field and magnetic field realize directional near-field measurement, making the measurement results more accurate and reliable, and realizing quantitative measurement. At the same time, the present invention eliminates the tedious processes of frequent disassembly and recalibration in the prior art. It eliminates the need for complex disassembly and assembly of the IGBT module and the design of a new busbar, reducing costs while also saving testing time and manpower and improving testing efficiency. By sampling background noise during the steady-state phase and dividing the double-pulse conduction, shutdown, and diode freewheeling time domains, it achieves separate measurement of electromagnetic interference during the IGBT forward conduction and reverse recovery of the anti-parallel diode. This provides a deeper understanding of the electromagnetic radiation characteristics of the IGBT module in different operating stages, providing more detailed information for electromagnetic compatibility design and fault diagnosis.

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the specific embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 This is a flow chart of a method for testing electromagnetic radiation characteristics of an IGBT module for a converter valve according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the wiring for the external double pulse test of the converter valve module;

[0038] Figure 3 This is a schematic diagram of the IGBT near-field probe layout;

[0039] Figure 4 Schematic diagram of the current path of the IGBT half-bridge in the converter valve module. DETAILED DESCRIPTION

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0041] In one possible implementation, combining Figures 1 to 4 As shown, the electromagnetic radiation characteristic test process of the upper tube IGBT module provided in this embodiment is as follows:

[0042] S101, select the upper IGBT to be tested. Figure 2 Connection method 1: Connect the inductive load to the first and second terminals of the converter valve, respectively. Terminal 1 is the neutral point between the top and bottom IGBTs. Ensure the bottom IGBT is always off, ensuring that the dual-pulse circuit aligns with the actual operating path without changing the metal structure of the converter valve and without disassembling the valve body.

[0043] It should be noted that the first and second terminals refer to the two terminals on the converter valve port (which can serve as both an input and an output). The first terminal is connected to the neutral point between the top and bottom IGBTs. It should be understood that this connection to the neutral point between the top and bottom IGBTs is a characteristic of the converter valve's design.

[0044] S102. Arrange combined electromagnetic field probes around the upper tube IGBT and lower tube IGBT to be tested. The probe housing is grounded to the valve body of the converter valve. The leads of each probe are centrally introduced into the photoelectric converter using shielded twisted-pair cables and connected to the signal conversion device.

[0045] Preferably, combined Figure 3 As shown, a combined electromagnetic field probe is installed in four directions around the upper tube IGBT and the lower tube IGBT to be tested, front, back, left, and right, at a moderate and consistent distance, to collect electromagnetic signals radiated in different directions.

[0046] S103. Complete the connection and installation of power cables, optical fibers, probes, and other equipment. The host computer controls the high-voltage DC power supply to charge the bus capacitor to a predetermined voltage using a constant current and stabilize the voltage. Simultaneously, the IGBT driver board, switching power supply, test probe, and other equipment are powered on and self-tested to ensure that the measurement results reflect the inherent background interference of the test system.

[0047] S104. In the static state where the IGBT is not triggered and the gate driver board, switching power supply, and all devices have completed power-on self-test, the background electromagnetic interference signal inside the converter valve module is collected through the probe, and the background noise inside the converter valve module is recorded to provide a reference for subsequent electromagnetic signal processing.

[0048] S105. Set the bus voltage value, pulse width, pulse interval time and number of repeated tests of the double pulse through the host computer interface.

[0049] S106, start executing the double pulse control signal, and perform the on and off operation on the upper tube IGBT through the driving circuit. The host computer sets the on pulse width and off pulse interval parameters, and sends them to the driving board through the optical fiber to trigger the upper tube IGBT to be tested to perform the double pulse on and off action. Figure 4 The current flow path shown.

[0050] During the test, the probe measurement results are converted into optical signals through a photoelectric converter, transmitted to an external device via optical fiber, restored to electrical signals, and transmitted to the host computer for processing.

[0051] S107. If the test number has not been reached, the bus voltage drops due to discharge, and the bus capacitor is charged to the test voltage before S106 is performed; if the test number has been reached, continue with S108.

[0052] S108. The electromagnetic interference data obtained from each test round is combined with the previously recorded background noise for data processing. The background noise signal is subtracted to obtain the electromagnetic interference intensity caused by the dynamic behavior of the top-side IGBT module (i.e., the net radiated electromagnetic signal reflecting the actual turn-on, turn-off, and diode freewheeling phases of the IGBT and its associated busbars). When testing the top-side IGBT, the top-side probe signal corresponds to the top-side IGBT forward conduction turn-on / turn-off radiation; the bottom-side probe signal corresponds to the bottom-side IGBT anti-parallel diode freewheeling / reverse recovery radiation, achieving separate measurement of the radiated electromagnetic interference during the IGBT forward conduction and reverse freewheeling processes.

[0053] After the test is completed, the system controls the bus capacitor to discharge and the power supply to all equipment is disconnected.

[0054] In one possible implementation, combining Figures 1 to 4 As shown, the electromagnetic radiation characteristic test process of the lower tube IGBT module provided in this embodiment is specifically as follows:

[0055] S201, select the lower IGBT to be tested. Figure 2 Connection method 2 uses a high-current wiring harness to connect the inductive load across the first terminal of the converter valve and the exposed positive terminal of the bus capacitor, while keeping the upper IGBT off. This ensures that the dual-pulse circuit aligns with the actual operating path, eliminating the need to disassemble or modify the valve body. The exposed positive terminal of the bus capacitor is configured as an exposed copper busbar for direct connection to the current harness of the inductive load circuit.

[0056] S202. Arrange combined electromagnetic field probes around the upper tube IGBT and lower tube IGBT to be tested. The probe housing is grounded to the valve body of the converter valve. The leads of each probe are centrally introduced into the photoelectric converter using shielded twisted-pair cables and connected to the signal conversion device.

[0057] S203: Complete the connection and installation of power cables, optical fibers, probes, and other equipment. The host computer controls the high-voltage DC power supply to charge the bus capacitor to a predetermined voltage using a constant current method and stabilize the voltage. Simultaneously, the IGBT driver board, switching power supply, test probe, and other equipment are powered on and self-tested.

[0058] S204. In a static state where the IGBT is not triggered and the gate driver board, the switching power supply, and all devices have completed power-on self-test, a probe is used to collect the background electromagnetic interference signal inside the converter valve module and record the background noise inside the converter valve module.

[0059] S205. Set the bus voltage value, pulse width, pulse interval time and number of repeated tests of the double pulses through the host computer interface.

[0060] S206, start executing the double pulse control signal, and perform the on and off operation on the lower tube IGBT through the driving circuit. The host computer sets the on pulse width and off pulse interval parameters, and sends them to the driving board through the optical fiber to trigger the lower tube IGBT to be tested to perform the double pulse on and off action. Figure 4 The current flow path shown.

[0061] During the test, the probe measurement results are converted into optical signals through a photoelectric converter, transmitted to an external device via optical fiber, restored to electrical signals, and transmitted to the host computer for processing.

[0062] S207. If the test number has not been reached, the bus voltage drops due to discharge, and the bus capacitor is charged to the test voltage before S206 is performed; if the test number has been reached, continue with S208.

[0063] S208. The electromagnetic interference data obtained from each test round is combined with the previously recorded background noise and processed. The background noise signal is subtracted to obtain the electromagnetic interference intensity caused by the dynamic behavior of the bottom-side IGBT module. When testing the bottom-side IGBT, the bottom-side probe signal corresponds to the forward conduction, turn-on / off radiation of the bottom-side IGBT; the top-side probe signal corresponds to the freewheeling / reverse recovery radiation of the top-side IGBT's anti-parallel diode. This allows for separate measurement of the radiated electromagnetic interference during the forward conduction and reverse freewheeling processes of the IGBT.

[0064] After the test is completed, the system controls the capacitor to discharge and all equipment power is disconnected.

[0065] In addition to the aforementioned embodiments, a more preferred embodiment employs a combined electromagnetic field probe comprising an electric field probe and a magnetic field probe. To avoid coupling and mutual interference between the probes during electromagnetic field measurements, the electric and magnetic field probes are tested sequentially, employing a time-sharing independent measurement mode. During the two independent measurement modes, the busbar capacitor voltage, gate drive pulse width, inductive load connection method, and test environment remain consistent. During the first measurement, only the electric field probe is used to record the electric field signal; during the second measurement, only the magnetic field probe is used to record the magnetic field signal. The electric and magnetic field signals obtained from these two measurements are processed separately to analyze the electromagnetic interference characteristics.

[0066] It should be understood that the host computer has a built-in noise separation algorithm, which automatically divides the radiation signals into the forward conduction and reverse freewheeling phases based on the IGBT switching timing. During data processing, the noise separation algorithm is used to separate the electromagnetic interference signals at different stages.

[0067] Preferably, the high-voltage DC power supply adopts a constant current charging mode, and the charging rate is dynamically controlled by the host computer. During the test, the charging rate is adjusted in real time by the host computer to ensure that the bus capacitor is charged to a stable voltage.

[0068] Through the above specific implementation methods, the present invention can simulate the electromagnetic radiation characteristics of the IGBT module during the switching process in the converter valve module, and realize the repeatable and quantitative measurement of the intensity and characteristics of the IGBT radiation source in the near-field space, providing a basis for the electromagnetic compatibility design and shielding reinforcement of the converter valve module, and at the same time providing data support for the health status inversion of the power module and the establishment of the life prediction model.

[0069] The embodiment of the present invention provides a system for testing electromagnetic radiation characteristics of an IGBT module for a converter valve, which is used to implement the above-mentioned method for testing electromagnetic radiation characteristics of an IGBT module for a converter valve, specifically comprising:

[0070] The converter valve module includes a half-bridge structure of an upper IGBT and a lower IGBT connected in parallel, providing a first terminal, a second terminal and an exposed positive terminal of the bus capacitor. The first terminal is the neutral point between the upper IGBT and the lower IGBT.

[0071] Preferably, the exposed positive terminal of the bus capacitor is configured as an exposed copper busbar structure for directly connecting to the current harness of the inductive load loop.

[0072] The switchable load circuit consists of an inductive load and a current harness. By selecting to connect the first terminal and the second terminal, or the first terminal and the exposed positive terminal of the bus capacitor, the upper tube IGBT / lower tube IGBT test mode is switched.

[0073] The near-field probe array includes a combined electromagnetic field probe distributed around the upper tube IGBT and the lower tube IGBT, and the probe housing is conductively connected to the valve body of the converter valve.

[0074] Preferably, the combined electromagnetic field probe is an integration of an electric field probe and a magnetic field probe, and each probe lead is centrally introduced into the photoelectric converter using a shielded twisted pair cable.

[0075] The photoelectric isolation transmission unit, including a photoelectric converter and optical fiber, converts the probe electrical signal into an optical signal for transmission and restores the optical signal to an electrical signal.

[0076] The control center includes a high-voltage DC power supply, a host computer, and an optical signal generator, and is used for bus capacitor charging, dual-pulse parameter transmission, signal processing, and background noise calibration.

[0077] Preferably, the high-voltage DC power supply adopts a constant current charging mode, and the charging rate is dynamically controlled by the host computer. The host computer has a built-in noise separation algorithm that automatically divides the radiation signal of the forward conduction and reverse freewheeling phases according to the IGBT switching time.

[0078] This method connects an inductive load via the converter valve's external lead-out path and its own port, completing dual-pulse testing of both the top-tube IGBT and the bottom-tube IGBT without disassembling the valve module's metal structure. This preserves the true parasitic parameters of the laminated busbar, ensuring that the dv / dt and di / dt at the turn-on and turn-off moments are consistent with field operating conditions. The measurement results are consistent with the IGBT module's operational scenarios in real engineering projects. Compared to the prior art practice of disassembling the IGBT module for far-field or darkroom scanning, this method avoids assembly and disassembly errors, the introduction of spurious parameters from additional fixtures, and changes in the radiation environment.

[0079] The present invention uses near-field probes and photoelectric isolation to measure electromagnetic interference, adopts time-sharing independent measurement to avoid mutual interference between probes, and transmits the electromagnetic interference results to the host computer for processing via optical fiber, thereby realizing directional measurement of radiated electromagnetic interference and improving data signal-to-noise ratio and test safety.

[0080] The present invention installs electromagnetic field probes in both the upper and lower IGBT modules. Under dual-pulse excitation, electromagnetic signals are collected in real time and background noise is subtracted. Depending on the timing of the on / off triggers, the upper and lower IGBT modules operate in either forward conduction or reverse freewheeling mode. The power modules operate in opposite directions, enabling separate measurements of radiated electromagnetic interference (EMI) during forward conduction and reverse freewheeling within the same converter valve.

[0081] In the description of the present invention, it should be understood that the terms "upper", "lower", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0082] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0083] In the present invention, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can mean fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0084] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0085] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0086] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above-mentioned embodiments, ordinary technicians in this field should understand that any technician familiar with this technical field can still modify the technical solutions recorded in the above-mentioned embodiments within the technical scope disclosed by the present invention, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered by the protection scope of the present invention.

Claims

1. A method for testing electromagnetic radiation characteristics of an IGBT module for a converter valve, characterized in that: include: Select the inductive load connection method based on the position of the IGBT to be tested. If testing the top IGBT, connect the two ends of the inductive load to the first terminal and the second terminal of the converter valve, respectively. The first terminal is the neutral point between the top and bottom IGBTs. If testing the bottom IGBT, connect the two ends of the inductive load to the first terminal of the converter valve and the exposed positive terminal of the bus capacitor, respectively. Arrange combined electromagnetic field probes around the upper and lower IGBTs to be tested. The probe housings are grounded to the converter valve body, and the leads of each probe are connected to a signal conversion device. After charging the bus capacitor to a stable voltage, the ambient noise of the converter valve is collected using a probe in the absence of gate triggering. The on-pulse width and off-pulse interval parameters are set by the host computer and sent to the driver board via optical fiber to trigger the IGBT to be tested to perform double pulse on-off action; The electrical signal output by the probe is converted into an optical signal by a photoelectric converter, and then transmitted to an external device through an optical fiber and restored to an electrical signal; Subtract the background noise from the double-pulse measurement results to extract the net radiated electromagnetic signals during the turn-on, turn-off and diode freewheeling phases of the IGBT under test. According to the switching moment of the IGBT to be tested, the electromagnetic interference signals of the forward conduction turn-on / turn-off process and the reverse freewheeling / reverse recovery process are separated.

2. The electromagnetic radiation characteristic testing method of an IGBT module for a converter valve according to claim 1, characterized in that: The combined electromagnetic field probe includes an electric field probe and a magnetic field probe. The electric field probe and the magnetic field probe adopt a time-sharing independent measurement mode. During the two independent measurement modes, the bus capacitor voltage, gate drive pulse width, inductive load connection method and test environment remain consistent.

3. The electromagnetic radiation characteristic testing method of an IGBT module for a converter valve according to claim 1, characterized in that: The method of separating the electromagnetic interference signals of the forward conduction turn-on / turn-off process and the reverse freewheeling / reverse recovery process according to the switching moment of the IGBT to be tested is specifically as follows: When testing the top IGBT, the top probe signal corresponds to the top IGBT forward conduction turn-on / turn-off radiation; the bottom probe signal corresponds to the bottom IGBT anti-parallel diode freewheeling / reverse recovery radiation; When testing the lower IGBT, the lower probe signal corresponds to the forward conduction turn-on / turn-off radiation of the lower IGBT; the upper probe signal corresponds to the freewheeling / reverse recovery radiation of the upper IGBT anti-parallel diode.

4. The method for testing electromagnetic radiation characteristics of an IGBT module for a converter valve according to claim 1, characterized in that: The following conditions must be met when collecting the background noise of the converter valve environment: The gate driver board, switching power supply and all equipment complete power-on self-test.

5. The method for testing electromagnetic radiation characteristics of an IGBT module for a converter valve according to claim 1, characterized in that: The double pulse parameters also include the busbar capacitor voltage value and the number of repeated tests, which are dynamically set by the host computer; The results of repeated tests were averaged to improve the signal-to-noise ratio.

6. A system for testing electromagnetic radiation characteristics of an IGBT module for a converter valve, used to implement the method for testing electromagnetic radiation characteristics of an IGBT module for a converter valve according to any one of claims 1 to 5, characterized in that: include: The converter valve module includes a half-bridge structure of an upper IGBT and a lower IGBT connected in parallel, and provides a first terminal, a second terminal, and an exposed positive terminal of a bus capacitor. The first terminal is a neutral point between the upper IGBT and the lower IGBT. The switchable load circuit consists of an inductive load and a current harness. By connecting the first terminal to the second terminal, or the first terminal to the exposed positive terminal of the bus capacitor, the upper IGBT / lower IGBT test mode can be switched. A near-field probe array includes a combination of electromagnetic field probes distributed around the upper tube IGBT and the lower tube IGBT, and the probe housing is conductively connected to the valve body of the converter valve; Photoelectric isolation transmission unit, including photoelectric converter and optical fiber, converts the probe electrical signal into optical signal for transmission, and restores the optical signal into electrical signal; The control center includes a high-voltage DC power supply, a host computer, and an optical signal generator, and is used for bus capacitor charging, dual-pulse parameter transmission, signal processing, and background noise calibration.

7. The electromagnetic radiation characteristics testing system for an IGBT module for a converter valve according to claim 6, characterized in that: The combined electromagnetic field probe is an integration of an electric field probe and a magnetic field probe, and each probe lead is centrally introduced into the photoelectric converter using a shielded twisted pair cable.

8. The method for testing electromagnetic radiation characteristics of an IGBT module for a converter valve according to claim 6, characterized in that: The exposed positive terminal of the bus capacitor is configured as an exposed copper busbar structure for directly connecting to a current harness of an inductive load loop.

9. The electromagnetic radiation characteristics testing system for an IGBT module for a converter valve according to claim 6, characterized in that: The host computer has a built-in noise separation algorithm, which automatically divides the radiation signals in the forward conduction stage and the reverse freewheeling stage according to the IGBT switching moment.

10. The electromagnetic radiation characteristics testing system for an IGBT module for a converter valve according to claim 6, characterized in that: The high-voltage direct current power supply adopts a constant current charging mode, and the charging rate is dynamically controlled by the host computer.

Images