A static test system for integrated bus capacitor power modules

Abstract

This invention provides a static testing system for an integrated bus capacitor power module, relating to the field of power device technology. The system includes a capacitor charging / discharging module, a static testing module, a switching module, and a module under test (DUT). The DUT is integrated with a three-phase full-bridge IGBT module and a bus capacitor. Before static testing, the bus capacitor is pre-charged using an independent charging / discharging circuit to stabilize its voltage and avoid interference with test accuracy due to capacitor energy storage effects. After testing, residual charge is safely released through a discharge branch to prevent high-voltage residue from posing a hazard to personnel and equipment. The entire testing process is automatically switched via a relay array, enabling continuous static parameter testing of multiple IGBT modules, including collector-emitter saturation voltage, leakage current, and gate threshold voltage.

Description

Technical Field

[0001] This invention relates to the field of power device technology, and more specifically to a static testing system for an integrated bus capacitor power module. Background Technology

[0002] In the development and factory screening of power semiconductor modules, static parameter testing has always been regarded as a core link in measuring the intrinsic characteristics of devices and ensuring long-term reliability. Measuring the static parameter characteristics of power modules is mainly to characterize the intrinsic characteristics of devices, which are relevant parameters independent of operating conditions, such as the static DC parameters of power devices. The current industry generally follows standards such as IEC 60747-9:2019 to perform static testing on individual IGBT modules. For example, it measures discrete IGBTs or MOSFETs for items such as collector-emitter saturation voltage drop, cutoff leakage current, and gate threshold voltage. The test circuit is simple and the number of terminals under test is small, so it is easy to complete the voltage application, sampling and discharge in a very short time, and the data reproducibility is high. However, with the continuous improvement of the requirements for power density and bus harmonic suppression in new energy converters, servo drives and vehicle electric drive systems, integrated bus capacitor power modules have emerged. This structure directly connects a large-capacity DC support capacitor in parallel across the two ends of a three-phase full-bridge power semiconductor chip, reducing the stray inductance of the circuit with the shortest path and significantly improving the switching performance of the device and the overall efficiency. While the introduction of bus capacitors optimizes dynamic operating conditions, it brings unprecedented challenges to the traditional static testing process: in actual work, there are integrated bus capacitor power modules, and the capacitance on their buses affects the static testing process and results.

[0003] Specifically, firstly, in the test V CES During testing, charging the bus capacitor not only prolongs the measurement time but also affects the test data before it is fully charged. Furthermore, the charging and discharging of the bus capacitor during the test prolongs the test time. The residual charge in the bus capacitor can be released instantaneously upon contact or rewiring, resulting in a high-voltage discharge that may cause electric shock to the operator or burn out the instrument, posing a significant safety hazard.

[0004] In view of the above, this application is hereby submitted. Summary of the Invention

[0005] This invention provides a static testing system with an integrated bus capacitor power module, which can at least partially improve the above-mentioned problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A static testing system integrating a bus capacitor power module includes: a control module, a capacitor charging and discharging module, a static testing module, a switch module, a module under test, and a switching module. The module under test is connected to the static testing module through the switch module, and the output terminal of the control module is connected to the control terminal of the capacitor charging and discharging module, the control terminal of the static testing module, the control terminal of the switch module, and the control terminal of the switching module.

[0008] The capacitor charging and discharging module is configured to precharge the bus capacitor in the module under test; the static test module is configured to provide static test conditions to the module under test and perform static testing; the switching module is configured to switch the IGBT power module in the module under test; and the switching module is configured to switch the relay between the capacitor charging and discharging module and the static test module.

[0009] The control module is configured to perform the following steps by executing a computer program stored internally:

[0010] The bus capacitor in the module under test is pre-charged using the capacitor charging and discharging module to ensure that the bus capacitor reaches a stable voltage state.

[0011] The static test module is controlled to provide static test conditions to the IGBT power module in the module under test, perform static tests, and collect its static characteristic parameters;

[0012] The IGBT power modules are switched using the switching module, and static tests are performed on the switched IGBT power modules until all IGBT power modules in the tested module have completed the static test and the test results are obtained.

[0013] The capacitor charging and discharging module is used to discharge the bus capacitor in the module under test to eliminate the impact of residual charge on test accuracy and the safety of test personnel.

[0014] In summary, this system includes a capacitor charging / discharging module, a static testing module, a switching module, and a module under test (DUT). The DUT is integrated with a three-phase full-bridge IGBT module and a bus capacitor. Before static testing, the system pre-charges the bus capacitor using an independent charging / discharging circuit to stabilize its voltage and avoid interference with test accuracy due to capacitor energy storage effects. After testing, residual charge is safely released through a discharge branch to prevent high-voltage residue from posing a hazard to personnel and equipment. The entire testing process is automatically switched via a relay array, enabling continuous static parameter testing of multiple IGBT modules, including collector-emitter saturation voltage, leakage current, and gate threshold voltage. This invention effectively solves the problems of long testing time, large data deviation, and high safety risks associated with traditional static testing methods for integrated bus capacitor power modules. It significantly improves testing efficiency, accuracy, and automation, and is suitable for batch testing of high-voltage power modules in new energy, electric drive, and other fields. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the main circuit of the static test system for the integrated bus capacitor power module provided in an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the static test process of the static test system for the integrated bus capacitor power module provided in an embodiment of the present invention.

[0017] Figure 3 This is a circuit diagram of the switching module of the static test system for the integrated bus capacitor power module provided in an embodiment of the present invention.

[0018] Figure 4 This is a circuit diagram of the module under test in the static test system of the integrated bus capacitor power module provided in an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] refer to Figure 1 As shown, the first embodiment of the present invention discloses a static test system for an integrated bus capacitor power module, which includes: a control module, a capacitor charging and discharging module, a static test module, a switch module, a module under test, and a switching module. The module under test is connected to the static test module through the switch module, and the output terminal of the control module is connected to the control terminal of the capacitor charging and discharging module, the control terminal of the static test module, the control terminal of the switch module, and the control terminal of the switching module.

[0021] The capacitor charging and discharging module is configured to precharge the bus capacitor C1 in the module under test; the static test module is configured to provide static test conditions to the module under test and perform static testing; the switching module is configured to switch the IGBT power module in the module under test; and the switching module is configured to switch the relay between the capacitor charging and discharging module and the static test module.

[0022] Specifically, in this embodiment, the system introduces an independent charging and discharging circuit into the testing system. By charging and discharging the bus capacitor C1 separately, the measurement deviation caused by the capacitance storage effect in the traditional testing method can be effectively overcome. This solves the problems that the bus capacitor will prolong the measurement time and affect the test results in static testing, and that the residual charge of the bus capacitor may pose a safety hazard. This significantly improves the accuracy and reliability of static parameter testing.

[0023] Please see Figure 4 Preferably, in this embodiment, the module under test includes a bus capacitor C1, six IGBT transistors, and six diodes FRD corresponding to the IGBT transistors. Each IGBT transistor is connected in parallel with its corresponding diode FRD to form an IGBT power module, resulting in a total of six IGBT power modules. The first IGBT power module Q1 is connected in series with the second IGBT power module Q2, the third IGBT power module Q3 is connected in series with the fourth IGBT power module Q4, and the fifth IGBT power module Q5 is connected in series with the sixth IGBT power module Q6, forming three upper and lower bridge arm circuits. The three upper and lower bridge arm circuits are connected in parallel to form a three-phase full-bridge power module. The bus capacitor C1 is connected in parallel across the two ends of the three-phase full-bridge power module to form an integrated bus capacitor power module. Two terminals are led out from the two ends of the bus capacitor C1, namely the first terminal CP and the second terminal CN.

[0024] Each of the IGBT power modules includes six terminals: collector terminal CQ, terminal CSQ, gate terminal GQ, terminal GSQ, emitter terminal EQ, and terminal ESQ.

[0025] Specifically, in this embodiment, the module under test includes a bus capacitor C1 and a three-phase full-bridge power module. The bus capacitor C1 is connected in parallel across the three-phase full-bridge power module to form an integrated bus capacitor power module, which is the module under test. The three-phase full-bridge power module consists of six IGBT power modules, with each pair of IGBT power modules forming an upper and lower bridge arm circuit, for a total of three upper and lower bridge arm circuits.

[0026] Among them, the IGBT transistor and the diode FRD are connected in parallel to form the first IGBT power module Q1, the second IGBT power module Q2, the third IGBT power module Q3, the fourth IGBT power module Q4, the fifth IGBT power module Q5, and the sixth IGBT power module Q6 (i.e., Figure 2 (Modules Q1 to Q6 in the IGBT module). Taking the first IGBT power module Q1 as an example, it has six terminals: collector terminal CQ1, terminal CSQ1, gate terminal GQ1, terminal GSQ1, emitter terminal EQ1, and terminal ESQ1. Similarly, the second, third, fourth, fifth, and sixth IGBT power modules Q2, Q3, Q4, Q5, and Q6 also have six terminals, just like the first IGBT power module Q1.

[0027] Please see Figure 3 Preferably, in this embodiment, the switching module includes thirty-six output terminals, six input terminals, and thirty-six switching relays (i.e., K11, K12, K13, K14, K15, K16, K21, K22, K23, K24, K25, K26, K31, K32, K33, K34, K35, K36, K41, K42, K43, K44, K45, K46, K51, K52, K53, K54, K55, K56, K61, K62, K63, K64, K65, K66). The input terminals are connected to the terminals of the IGBT power module of the module under test through the switching relays.

[0028] In this embodiment, the switching module is used to select and switch the power modules to improve testing efficiency. Taking input terminal C1 as an example, it is connected to terminals CQ1, CQ2, CQ3, CQ4, CQ5, and CQ6 of IGBT power modules Q1, Q2, Q3, Q4, Q5, and Q6 in the module unit under test via relays K11, K12, K13, K14, K15, and K16, respectively.

[0029] Specifically, the six input terminals in the switching module are connected to the terminals via switching relays, as described above. This enables switching between different IGBT power modules. The relays included in the switching module are referred to as the terminal relay section.

[0030] Preferably, in this embodiment, the capacitor charging and discharging module includes a power resistor R2 and a third relay K3. One end of the power resistor R2 is connected to the first terminal CP of the bus capacitor C1 of the module under test, and the other end of the power resistor R2 is connected to the third relay K3. The fifth contact 5 of the third relay K3 is connected to the first relay K1 of the switching module, and the sixth contact 6 of the third relay K3 is connected to the second terminal CN of the bus capacitor C1 of the module under test.

[0031] In this embodiment, the capacitor charging and discharging module connects to the voltage source and fuse via a switching relay to achieve controlled charging of the bus capacitor C1, thereby ensuring the charging and discharging of the capacitor and maintaining its state. Specifically, the capacitor charging and discharging circuit switches to the discharge branch via a relay, allowing the energy in the bus capacitor C1 to be released in a controlled manner, avoiding any impact on test data and equipment.

[0032] Preferably, in this embodiment, the switching module includes a first relay K1 and a second relay K2. The second terminal CN of the bus capacitor C1 of the module under test is connected to the fourth contact 4 of the second relay K2, and the second contact 2 of the first relay K1 is connected to the third relay K3 of the capacitor charging and discharging module.

[0033] In this embodiment, the switching module achieves the switching between the charging / discharging circuit and the testing circuit through the above-described connection.

[0034] Preferably, in this embodiment, the static test module includes a first voltage source VCC, a second voltage source VGG, a current source ICC, a first fuse R1, a third fuse R3, a fourth relay K4, a fifth relay K5, a sixth relay K6, a seventh relay K7, an eighth relay K8, a ninth relay K9, a voltmeter, and an ammeter. One end of the voltmeter is connected to terminal ES of the switching module, another end is connected to terminal CS of the switching module via the eighth relay K8, and another end is connected to terminal GS of the switching module via the ninth relay K9. The current source ICC is connected in series with the fifth relay K5. The first voltage source VCC is connected in series with the fourth relay K4 and the first fuse R1. After being connected in series, they are connected in parallel. One end of this parallel circuit is connected to the first relay K1, and the other end of this parallel circuit is connected to the second relay K2. The first contact 1 of the first relay K1 is connected to the terminal C of the switch module through an ammeter. The third contact 3 of the second relay K2 is connected to the terminal E of the switch module through a seventh relay K7. The second voltage source VGG is connected in series with the third fuse R3, the sixth relay K6, and the ammeter. One end of this series circuit is connected to the terminal E of the switch module, and the other end of this series circuit is connected to the terminal G of the switch module.

[0035] Specifically, in this embodiment, the static test module includes a static test circuit comprising a voltmeter and an ammeter for acquiring and recording the static electrical parameters of the power module under test; a number of relays for switching between different test circuits; two fuses for overload protection; and a voltage source and a current source for providing test conditions to the power module under test and powering the capacitor charging / discharging unit. This module switches between multiple relays to select different test paths, meaning that different static test targets can be switched by turning different relays on and off. This allows for the testing of different static parameters of the power module under test, including at least collector-emitter saturation voltage, gate-emitter voltage, leakage current, and collector cutoff current. This method effectively eliminates the potential interference of capacitor storage effects on measurement data and avoids test deviations.

[0036] Please see Figure 2 The control module is configured to perform the following steps by executing a computer program stored internally:

[0037] S1, the bus capacitor C1 in the module under test is pre-charged using the capacitor charging and discharging module to ensure that the bus capacitor C1 reaches a stable voltage state.

[0038] Specifically, in this embodiment, taking the first IGBT power module Q1 as an example, the static testing process of the integrated bus capacitor power module is described. First, during the capacitor charging stage, as... Figure 1 As shown, the first relay K1 is switched to the second contact 2, the second relay K2 is switched to the fourth contact 4, and the charging circuit is connected. The third relay K3 switches to contact 5, the fourth relay K4 is closed, and the fifth relay K5 is opened. At this time, the bus capacitor C1 is charged until the charging is complete.

[0039] S2, control the static test module to provide static test conditions to the IGBT power module in the module under test, perform static test, and collect its static characteristic parameters;

[0040] S3, the IGBT power modules are switched through the switching module, and static tests are performed on the switched IGBT power modules until all IGBT power modules in the tested module have completed the static test and the test results are obtained;

[0041] Specifically, in this embodiment, during the static testing phase, the first relay K1 is switched to the first contact 1, the second relay K2 is switched to the third contact 3, and the test circuit is connected. The temperature is set to a specified value, and the third relay K3 does not activate. Figure 3As shown, on the terminal connection side, closed switch relays K11, K21, K31, K41, K51, and K61, while the remaining switch relays in the terminal relay section are open.

[0042] Among them, the collector-emitter voltage (V) is tested. CES ),like Figure 1 As shown, shorting terminals G and E disconnects relays K5, K6, and K9, while closing relays K4, K7, and K8, increasing V. CES Continue until the specified value is reached, and measure the current I. CES Test collector-emitter saturation voltage V CEsat Relays K4 and K9 are open, while relays K5, K6, K7, and K8 are closed. The first voltage source VCC, combined with the third fuse R3, provides a constant collector current pulse. The pulse width can be set to 50. --300 Within this range. The pulse is long enough to achieve complete output saturation. Measuring this collector-emitter voltage gives the saturation voltage V. CEsat Test the gate-emitter threshold voltage. VGE（th） Relays K5 and K8 are open, while relays K4, K6, K7, and K9 are closed, setting the collector-emitter voltage to the specified value. Gate-emitter voltage V GS It is increased until the specified collector current I is reached. C Measure the gate-emitter voltage V at this current. GE（th） Test collector cutoff current I CES Shorting terminals G and E disconnects relays K5, K6, and K9, while closing relays K4, K7, and K8, thus increasing voltage V. CE Continue until it reaches the specified value. Read I on an ammeter or current probe. CES Test gate leakage current I GES Short-circuit terminals C and E, relays K4, K5, K7, and K8 are open, and relays K6 and K9 are closed. The gate-emitter voltage is set to the specified value. Measure the gate-emitter leakage current I. GES .

[0043] Furthermore, after testing the first IGBT power module Q1, the system switches to other IGBT power modules via a switching module until all IGBT power modules have completed static testing. The static testing process described above can be simplified to a truth table for the static test module, as shown in Table 1. The first contact 1 of the first relay K1 is recorded as 1, and the second contact 2 as 0; the third contact 3 of the second relay K2 is recorded as 1, and the fourth contact 4 as 0; the fifth contact 5 of the third relay K3 is recorded as 1, and the sixth contact 6 as 0; and the closing of relays K4, K5, K6, K7, K8, and K9 is recorded as 1, and their opening as 0.

[0044] Table 1 Truth Table for Static Test Module

[0045]

[0046] S4. The capacitor charging and discharging module is used to discharge the bus capacitor in the module under test to eliminate the impact of residual charge on test accuracy and the safety of test personnel.

[0047] Specifically, in this embodiment, static testing can be completed through the above steps. After all IGBT power modules have been tested, the third relay K3 is switched to the sixth contact 6 to discharge, so as to prevent residual charge from causing harm to operators or test equipment.

[0048] In short, before static testing, this system first pre-charges the bus capacitor through an independent capacitor charging and discharging circuit to eliminate its influence on subsequent testing processes, thus avoiding interference from capacitor energy storage on test results. After pre-charging, the relay switches to the static testing module, where voltage and current sources provide test conditions to the power module under test, and static characteristic parameters are collected by voltmeters and ammeters. After testing one power module, the relay in the switching module selects and switches to another power module under test. After completing the static parameter test, the residual charge of the bus capacitor is released through the discharge branch, thus avoiding interference from the bus capacitor on measurement data, measurement time, and test safety. For power modules with integrated bus capacitors, this system effectively eliminates measurement deviations caused by capacitor storage effects, improving the efficiency, accuracy, and safety of static testing personnel.

[0049] In summary, this system retains the complete structure of the bus capacitor, three-phase full-bridge IGBT power module, and Kelvin terminals within the module under test. By utilizing a capacitor charging and discharging module to independently pre-charge the bus capacitor before testing, the bus voltage stabilizes in advance, fundamentally eliminating the time extension and current superposition errors caused by traditional "charging and testing simultaneously." During testing, the switching module isolates the bus capacitor from the sampling circuit, and the static testing module uses terminals to measure the V of each IGBT power module. CEsat VGE(th) I CES I GES Precise sampling of parameters ensures data is no longer affected by lead impedance and charging current. After testing, the system immediately discharges residual charge to a safe voltage below the controlled level via power resistor R2, avoiding the risk of arcing during manual insertion and removal, achieving "zero-wait" component replacement. Thus, this invention simultaneously improves the efficiency, accuracy, and safety of static testing without compromising the module's dynamic performance advantages, providing a reliable and scalable batch testing solution for high-voltage, high-power applications such as new energy vehicles, rail transit, and industrial frequency converters.

[0050] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A static testing system for an integrated bus capacitor power module, characterized in that, include: The system includes a control module, a capacitor charging / discharging module, a static test module, a switch module, a module under test, and a switching module. The module under test is connected to the static test module via the switch module. The output terminal of the control module is connected to the control terminals of the capacitor charging / discharging module, the static test module, the switch module, and the switching module. The module under test is integrated with a three-phase full-bridge IGBT module and a bus capacitor. The module under test includes a bus capacitor, six IGBT transistors, and six diodes (FRDs) corresponding to the IGBT transistors. Each IGBT transistor and its corresponding diode (FRD) are connected in parallel to form an IGBT power module, resulting in a total of six IGBT power modules. The first IGBT power module is connected in series with the second IGBT power module, the third IGBT power module is connected in series with the fourth IGBT power module, and the fifth IGBT power module is connected in series with the sixth IGBT power module, forming three upper and lower bridge arm circuits. The three upper and lower bridge arm circuits are connected in parallel to form a three-phase full-bridge power module. The bus capacitor is connected in parallel across the two ends of the three-phase full-bridge power module to form an integrated bus capacitor power module. Two terminals are led out from the two ends of the bus capacitor, namely the first terminal and the second terminal. The capacitor charging and discharging module is configured to precharge the bus capacitor in the module under test; the static test module is configured to provide static test conditions to the module under test and perform static testing; the switching module is configured to switch the IGBT power module in the module under test; and the switching module is configured to switch the relay between the capacitor charging and discharging module and the static test module. The control module is configured to perform the following steps by executing a computer program stored internally: The bus capacitor in the module under test is pre-charged using the capacitor charging and discharging module to ensure that the bus capacitor reaches a stable voltage state. The static test module is controlled to provide static test conditions to the IGBT power module in the module under test, perform static tests, and collect its static characteristic parameters; The IGBT power modules are switched using the switching module, and static tests are performed on the switched IGBT power modules until all IGBT power modules in the tested module have completed the static test and the test results are obtained. The capacitor charging and discharging module is used to discharge the bus capacitor in the module under test to eliminate the impact of residual charge on test accuracy and the safety of test personnel.

2. The static testing system for the integrated bus capacitor power module according to claim 1, characterized in that, Each of the IGBT power modules includes six terminals: collector terminal CQ, terminal CSQ, gate terminal GQ, terminal GSQ, emitter terminal EQ, and terminal ESQ.

3. The static testing system for the integrated bus capacitor power module according to claim 2, characterized in that, The switching module includes thirty-six output terminals, six input terminals, and thirty-six switching relays. The input terminals are connected to the terminals of the IGBT power module of the module under test through the switching relays. The six input terminals are terminal C, terminal E, terminal G, terminal CS, terminal ES, and terminal GS.

4. The static testing system for the integrated bus capacitor power module according to claim 3, characterized in that, The capacitor charging and discharging module includes a power resistor and a third relay. One end of the power resistor is connected to the first terminal of the bus capacitor of the module under test, and the other end of the power resistor is connected to the third relay. The fifth contact of the third relay is connected to the first relay of the switching module, and the sixth contact of the third relay is connected to the second terminal of the bus capacitor of the module under test.

5. The static testing system for the integrated bus capacitor power module according to claim 4, characterized in that, The switching module includes a first relay and a second relay. The second terminal of the bus capacitor of the module under test is connected to the fourth contact of the second relay, and the second contact of the first relay is connected to the third relay of the capacitor charging and discharging module.

6. The static testing system for the integrated bus capacitor power module according to claim 5, characterized in that, The static test module includes a first voltage source, a second voltage source, a current source, a first fuse, a third fuse, a fourth relay, a fifth relay, a sixth relay, a seventh relay, an eighth relay, a ninth relay, a voltmeter, and an ammeter. One end of the voltmeter is connected to terminal ES of the switch module, and the other end of the voltmeter is connected to terminal CS of the switch module via the eighth relay. The other end of the voltmeter is connected to terminal GS of the switch module via the ninth relay. The current source is connected in series with the fifth relay to form a first series circuit. The first voltage source, the fourth relay, and the first fuse are connected in series to form a second series circuit. The first and second series circuits are connected in parallel, with one end of the parallel circuit connected to the first relay and the other end connected to the second relay. The first contact of the first relay is connected to terminal C of the switch module via the ammeter, and the third contact of the second relay is connected to terminal E of the switch module via the seventh relay. The second voltage source, the third fuse, the sixth relay, and the ammeter are connected in series to form a third series circuit, with one end of the third series circuit connected to terminal E of the switch module and the other end connected to terminal G of the switch module.

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