Method, circuit and equipment for testing turn-off loss of device series module and medium

Abstract

The invention discloses a turn-off loss test method, a turn-off loss test circuit, turn-off loss test equipment and a turn-off loss test medium for a device series module, and relates to the field of device series module test. A main power device in the device series module to be tested is controlled to be turned on and turned off by using double pulses in the double-pulse test circuit, and then the turn-off loss of the device series module is calculated by using the terminal voltage of the device series module and the current flowing through the main power device and the auxiliary power device. Accurate test of the turn-off loss of the device series module is realized, and subsequent evaluation and application of the device series module are facilitated.

Description

Technical Field

[0001] The present invention relates to the field of device series module testing, and in particular to a method, circuit, equipment and medium for testing a turn-off loss of a device series module. Background Art

[0002] In the DC distribution network, the voltage source converter (referred to as the converter) connects the medium voltage AC and DC distribution networks, which has an important impact on the efficiency and volume of the distribution network system. At present, the AC / DC converter of the medium voltage distribution network generally adopts MMC (Modular Multilevel Converter). The MMC contains a large number of sub-modules (more than 144), each of which contains 2 IGBT (Insulated Gate Bipolar Transistor) devices and a capacitor of several mF. Therefore, there are problems of large footprint and high land cost, especially in urban load-intensive areas. The problem is more significant. In order to reduce the footprint of the MMC, a two-level converter can be made by directly connecting multiple power devices in series to form a device series module. The capacitor in the original MMC sub-module can be omitted, and the number of power devices can be reduced by half. Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a packaged device series module provided by the prior art; in the case of power devices connected in series, it is necessary to connect an ACM (Active Clamping Module) in parallel on the power side of each power device in series to achieve dynamic and static voltage balancing between the power devices, and the ACM includes auxiliary power devices and clamping capacitors connected in series. However, in the application process, considering the volume of the clamping capacitor, only the main power devices in series and the corresponding auxiliary power devices in the ACM are integrated and packaged to form a device series module, such as Figure 1 shown.

[0003] Before the application of the converter, it is necessary to Figure 1 The device series module shown is subjected to dynamic testing to obtain parameters such as driving voltage, power side voltage and current during the operation of the device series module, so as to achieve accurate application of the converter. In the prior art, the packaged module is generally directly connected to the test circuit for dynamic testing. However, since there are only main power devices and corresponding auxiliary power devices in the packaged device series module, during the switching process of the device series module, there may be significant uneven pressure in each of the series-connected main power devices, causing the semiconductor chip inside the main power device to break down due to overvoltage, and it is also impossible to obtain the true working parameters of the module. Summary of the invention

[0004] The purpose of the present invention is to provide a turn-off loss test method, circuit, equipment and medium for a device series module. By supplementing the structure of a capacitor in the test circuit, voltage equalization between each main power device in the device series module is achieved, and dynamic and static voltage equalization between the main power devices in the entire test process is ensured, thereby avoiding overvoltage of the semiconductor chip inside the main power device, and improving the accuracy and reliability of the working parameters of the device series module finally obtained, so as to analyze the dynamic parameters and working process status of the device series module according to accurate working parameters, evaluate the dynamic performance of the device series module, and facilitate the subsequent accurate application of the device series module.

[0005] In a first aspect, the present invention provides a method for testing a turn-off loss of a device series module, wherein the device series module to be tested is arranged in a double pulse test circuit; the method for testing a turn-off loss of the device series module comprises:

[0006] Starting the double pulse test circuit to control the turning on and off of each main power device in the series module of the device under test;

[0007] Obtaining operating parameters during the opening and closing process of the series module of the device under test;

[0008] The turn-off loss of the series module of the device under test is determined based on the operating parameters of the series module of the device under test.

[0009] Optionally, after determining the turn-off loss of the series module of the device under test based on the operating parameters of the series module of the device under test, the method further includes:

[0010] The turn-off loss of the series module of the device under test is corrected based on the operating parameters of the series module of the device under test and the operating parameters of the double pulse test circuit.

[0011] Optionally, the device series module to be tested includes a plurality of main power devices connected in series and auxiliary power devices corresponding one-to-one to the main power devices, the double pulse test circuit includes capacitors connected in series one-to-one to the auxiliary power devices of the device series module, and the circuit after the auxiliary power devices and the capacitors are connected in series is connected in parallel with the corresponding main power devices; obtaining the working parameters during the opening and closing process of the device series module to be tested includes:

[0012] When the main power device is turned off, the voltage across the series module of the device under test and the current flowing through the series module of the device under test are obtained;

[0013] When the main power device is turned off, the current of the loop where each capacitor is located and / or the voltage across both ends of each capacitor are obtained.

[0014] Optionally, the turn-off loss of the series module of the device under test is corrected based on the operating parameters of the series module of the device under test and the operating parameters of the double pulse test circuit, including:

[0015] Determine the current of any one of the loops where the capacitor is located;

[0016] Determine the corrected turn-off loss of the device series module based on a current correction relationship between the current of any one of the capacitor loops and the turn-off loss;

[0017] The current correction relationship is:

[0018] ;

[0019] in, is the turn-off loss of the device series module, is the real-time value of the voltage across the device series module, t x is the moment when the voltage across the device series module rises to 10% of the rated DC bus voltage during the shutdown process, t y is the moment when the current flowing through the device series module during the shutdown process drops to 10% of the current rating, i d is the real-time value of the current flowing through the device series module, i a It is the real-time value of the current in the loop where the capacitor is located.

[0020] Optionally, the turn-off loss of the series module of the device under test is corrected based on the operating parameters of the series module of the device under test and the operating parameters of the double pulse test circuit, including:

[0021] determining a voltage across any one of the capacitors;

[0022] Determine the corrected turn-off loss of the device series module based on the voltage across any one of the capacitors and the voltage correction relationship of the turn-off loss;

[0023] The voltage correction relationship is:

[0024] ;

[0025] in, is the turn-off loss of the device series module, is the real-time value of the voltage across the device series module, t x is the moment when the voltage across the device series module rises to 10% of the rated DC bus voltage during the shutdown process, t y is the moment when the current flowing through the device series module during the shutdown process drops to 10% of the current rating, i dis the real-time value of the current flowing through the device series module, N is the number of capacitors in the device series module, C is the capacitance of the capacitor, is the stable voltage value of the capacitor after the device series module is turned off, It is the stable voltage value of the capacitor when the device series module is turned on.

[0026] In a second aspect, the present invention provides a test circuit for a device series module, comprising a controller and a device series module to be tested, wherein the device series module to be tested comprises a plurality of main power devices connected in series and auxiliary power devices corresponding one-to-one to the main power devices, the double pulse test circuit comprises capacitors connected in series one-to-one to the respective auxiliary power devices of the device series module, the circuit after the auxiliary power devices and the capacitors are connected in series is connected in parallel with the corresponding main power devices, and the control ends of the main power devices and the auxiliary power devices are both connected to the controller;

[0027] The controller is used to implement the turn-off loss test method of the device series module as described in any one of claims 1 to 5.

[0028] Optionally, it further includes a discharge resistor and a bus capacitor, the discharge resistor and the bus capacitor are connected in parallel, and two ends of the parallel circuit are respectively connected to two ends of the DC bus.

[0029] Optionally, the output end of the controller is also connected to the control end of the double pulse test circuit, and the controller is also used to control the start and stop of the double pulse test circuit.

[0030] In a third aspect, the present invention provides an electronic device, comprising:

[0031] Memory for storing computer programs;

[0032] A processor is used to implement the steps of the method for testing the turn-off loss of a device series module as described above.

[0033] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the turn-off loss test method for a device series module as described above are implemented.

[0034] The present invention discloses a method, circuit, equipment and medium for testing the turn-off loss of a device series module. The method comprises the following steps: setting the device series module to be tested in a double pulse test circuit, using double pulses in the double pulse test circuit to control the main power device in the device series module to be tested to be turned on and off, and then using the working parameters of the device series module during the operation of the main power device to determine the turn-off loss of the device series module to be tested. The working parameters of the device series module under the action of the double pulse test circuit are used to analyze the dynamic parameters and working process status of the device series module. The method can effectively evaluate the dynamic performance of the device series module, realize the test of the turn-off loss of the device series module, and facilitate the subsequent accurate application of the device series module. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0036] Figure 1 A schematic diagram of the structure of a packaged device series module provided by the prior art;

[0037] Figure 2 A schematic flow chart of a method for testing the turn-off loss of a device series module provided by the present invention;

[0038] Figure 3 A schematic diagram of the structure of a test circuit for a device series module provided by the present invention;

[0039] Figure 4 A schematic diagram of a discharge circuit of a capacitor provided by the present invention;

[0040] Figure 5 A schematic diagram of signal waveforms during a test process of a device series module provided by the present invention;

[0041] Figure 6 A schematic diagram of signal waveforms during a simulation test of a device series module provided by the present invention;

[0042] Figure 7 The present invention provides a schematic structural diagram of an electronic device. DETAILED DESCRIPTION

[0043] The core of the present invention is to provide a turn-off loss test method, circuit, equipment and medium for a device series module. By supplementing the structure of a capacitor in the test circuit, voltage equalization between the main power devices in the device series module is achieved, ensuring dynamic and static voltage equalization between the main power devices during the entire test process, thereby avoiding overvoltage of the semiconductor chip inside the main power device, and improving the accuracy and reliability of the working parameters of the device series module finally obtained, so as to analyze the dynamic parameters and working process status of the device series module according to accurate working parameters, evaluate the dynamic performance of the device series module, and facilitate the subsequent accurate application of the device series module.

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Please refer to Figure 2 , Figure 2 A schematic diagram of a method for testing the turn-off loss of a device series module provided by the present invention; please refer to Figure 3 , Figure 3 This is a schematic diagram of a test circuit for a device series module provided by the present invention; please refer to Figure 4 , Figure 4 A schematic diagram of a discharge circuit of a capacitor provided by the present invention; In a first aspect, the present invention provides a method for testing a turn-off loss of a device series module, wherein the device series module to be tested is arranged in a double pulse test circuit; the method for testing a turn-off loss of a device series module comprises:

[0046] S11: Start the double pulse test circuit to control the opening and closing of each main power device in the series module of the device under test;

[0047] It is understandable that if Figure 3As shown, the double pulse test circuit includes a freewheeling power device Q2, a freewheeling inductor L1 and a device-to-be-tested series module Q1. The device-to-be-tested series module refers to the device-to-be-tested series module. The device-to-be-tested series module Q1 includes a number of main power devices connected in series and auxiliary power devices connected one-to-one with the main power devices. The freewheeling power device Q2 is connected in series with the main power device of the device-to-be-tested series module, and the two ends of the series-connected circuit are respectively connected to the two ends of the DC bus. The freewheeling inductor L1 is connected in parallel with the freewheeling power device Q2. The test circuit also includes capacitors connected in series with each auxiliary power device of the device-to-be-tested series module one-to-one. The circuit after the auxiliary power device and the capacitor are connected in series is connected in parallel with the corresponding main power device. During the test, the device-to-be-tested series module will be placed in the lower tube position in the double pulse test circuit.

[0048] It should be noted that a double pulse test circuit is generally used to test the dynamic characteristics of the device series module. Based on the double pulse test circuit, capacitors (C1, C2, ..., CN) need to be connected in parallel to the capacitor terminals (C1+, C1-, C2+, C2-...CN+, CN-) reserved after the device series module is packaged. Capacitors Ci are connected in parallel at Ci+ and Ci-, where i represents an integer between 1 and N. During the test, the capacitors added in parallel are used as clamping capacitors to form an active clamping circuit with the auxiliary power device to achieve voltage balancing between the main power devices (S1, S2, ..., SN).

[0049] When the double pulse test circuit is started, after setting the capacitors corresponding to each main power device, it is necessary to pre-charge the capacitors before the start of the first pulse (i.e., the 0-t1 stage) to ensure that the capacitance voltage v of each capacitor is c1 -v cN The clamping voltage has risen to the clamping voltage. The clamping voltage needs to be adjusted and set according to the specific size of the DC bus connected to the test circuit. When the number of main power devices in series in the device series module is N, N is a positive integer greater than 1, and the clamping voltage is V dc / N,V dc is the voltage of the DC bus; at the same time, since the freewheeling power device Q2 needs to remain in the off state throughout the test, it is necessary to turn off the freewheeling power device Q2 at the beginning of the test. At this time, the freewheeling inductor L1 and the parasitic diode of the auxiliary power device can be used to pre-charge each capacitor. Pre-charging can charge the voltage across each capacitor to V dc / N, thereby maintaining the voltage balance of each main power device in series.

[0050] After the capacitor is pre-charged, the dual pulse signal can be used to test the series module of the device under test. The dual pulse signal refers to two pulse signals, the second pulse signal is later than the first pulse signal, and the main power device of the series module of the device under test will receive the first pulse signal and the second pulse signal in sequence, and turn on when the pulse signal arrives, and turn off after the pulse signal disappears, thus performing an action process. During the switching process, the voltage and current of the power module under test can be obtained using instruments such as oscilloscopes and probes, so as to analyze and evaluate the dynamic characteristics of the series module of the device under test.

[0051] It is understandable that when the first pulse signal arrives, each main power device in the series module of the device under test will be turned on for a period of time and then turned off under the action of the first pulse signal. During the conduction process, the voltage applied to the inductor L1 is V dc , inductor current ( Figure 3 in i L ) increases linearly with a slope of V dc / L, the inductor current flows through the power module to be tested. Assume that the current I d To evaluate the switching characteristics of the power module under test, the time of the first pulse can be determined by V dc At the end of the first pulse, the power module under test is at I d The current is shut off.

[0052] After the power module to be tested is turned off, the inductor current i L The reverse diode of Q2 is used for freewheeling. At this time, the voltage drop applied to the inductor is only the voltage drop introduced by the reverse diode of Q2, the inductor and the parasitic resistance of the line. In addition, the interval between the first and second pulses is short, so it can be considered that the inductor current i L Next, a second pulse is applied to the power module to be tested, and the power module to be tested can be obtained at I d Turn-on characteristics under current.

[0053] By obtaining the voltage and current waveforms of the power to be measured through measuring instruments such as oscilloscopes, the turn-on and turn-off dynamic characteristics of the power module to be measured under a specific current can be analyzed.

[0054] Correspondingly, the test circuit charges the capacitor before the pulse signal arrives. After the test is completed using the double pulse signal, that is, after the second pulse signal ends (after t4), it is necessary to turn on all the auxiliary power devices in the device series module to discharge all the clamping capacitors. aThe driving circuits allocated to the auxiliary power devices Sa1-SaN turn on all the auxiliary power devices Sa1-SaN during the t5-t6 phase to discharge the clamping capacitor. To facilitate the discharge process of the capacitor, a discharge resistor connected in parallel at both ends of the DC bus can be further set in the test circuit so that the capacitor can be quickly discharged through the discharge resistor. The equivalent circuit of the test circuit during discharge is as follows: Figure 4 There are many options for the specific implementation of the third preset discharge time. Assuming that the capacitance of capacitors C1-CN is C and the resistance of the discharge resistor is R, the third preset discharge time t6-t5 is preferably greater than 3RC.

[0055] S12: Obtaining the operating parameters during the process of turning on and off the series module of the device under test;

[0056] By obtaining the voltage and current waveforms of the power to be measured through measuring instruments such as oscilloscopes, the turn-on and turn-off dynamic characteristics of the power module to be measured under a specific current can be analyzed.

[0057] S13: Determine the turn-off loss of the series module of the device under test based on the operating parameters of the series module of the device under test.

[0058] Please refer to Figure 5 , Figure 5 A schematic diagram of signal waveforms during the test of a device series module provided by the present invention; please refer to Figure 6 , Figure 6 The signal waveform diagram of the simulation test process of a device series module provided by the present invention; specifically, the entire test process includes the capacitor pre-charging stage, the first pulse stage, the freewheeling stage, the second pulse stage and the capacitor discharge stage. In the capacitor pre-charging stage (0-t1), the device series module under test and the freewheeling power device Q2 are both in the off state, and the DC bus V dc The capacitor C1-CN is pre-charged through the freewheeling inductor L1, and the capacitor voltage v c1 -v cN Charge to V dc / N. When the first pulse signal starts, the test process enters the first pulse stage (t1-t2), the device series module under test is turned on at t1 and turned off at t2. The turn-on time T1 of the device series module under test is T1=t2-t1; after the first pulse ends and before the second pulse starts, the test circuit will enter the freewheeling stage (t2-t3). At this time, the voltage drop applied to the inductor is only the voltage drop introduced by the Q2 anti-parallel diode, the inductor and the line parasitic resistance. In addition, the interval between the first and second pulses is short, so it can be considered that the inductor current i L Remain unchanged.

[0059] The signal timing diagram during the entire test process is as follows Figure 5 As shown, g is the driving signal of the device series module under test, v ds is the power terminal voltage of the device series module, i d is the current flowing through the device series module, g a is the driving signal of the auxiliary power device, v ci Yes c1 -v cN Typical waveform of capacitor voltage, V dc is the voltage value of the DC bus of the test circuit. g and g a The driving circuit can generate the driving voltage required by each main power device and auxiliary power device in the device series module. x Yes ds The time to rise to 10% of its rated value, v ds The rated value of the device series module when it is off is V dc , so t x Yes ds Rise to 10%V dc The moment; t y is i d When it drops to 10% of the rated value, i d The rated value is I d , so t y is i d Down to 10%I d moment.

[0060] It should be noted that the present application does not specifically limit the specific types and implementation methods of the freewheeling power device Q2, the freewheeling inductor L1, the main power device, the auxiliary power device and the capacitor; the main power device and the auxiliary power device can be implemented by controllable switch devices such as MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), IGBT (Insulated Gate Bipolar Transistor), etc. The freewheeling power device Q2 can be implemented by multiple series-connected power devices in the same way as the setting method of the device series module under test. At this time, it is also necessary to connect ACM in parallel at both ends of each series-connected power device to achieve voltage balancing between the series-connected power devices in the freewheeling power device Q2. Similarly, the ACM includes auxiliary power devices and clamping capacitors. The auxiliary power devices are arranged inside the module of the freewheeling power device Q2, and the clamping capacitors are added externally. Alternatively, the freewheeling power device Q2 can be directly implemented with a single high-voltage diode or a single high-voltage SiC MOSFET or IGBT, and the gate of the freewheeling power device Q2 is controlled to be in the off state. The test circuit may further include a bus capacitor Cin connected in parallel at both ends of the DC bus. The specific implementation of the test circuit is not specifically limited in this application, including but not limited to the circuit structure proposed in this application. The specific number and implementation of the main power device in the device series module are not specifically limited in this application. The main power device can be implemented by multiple semiconductor power chips connected in series.

[0061] Different from the traditional double pulse test, since each main power device of the module under test is connected in parallel with a clamping capacitor, the current i d The falling slope is significantly slowed down. In the actual double pulse test circuit, there is usually parasitic inductance in the DC loop. When the module to be tested is turned off, the current of the parasitic inductance in series with it needs to be switched from I d Reduced to 0. In the traditional double pulse test, after the device under test is turned off, the parasitic inductance charges the junction capacitance of the device under test, and a voltage spike appears in the device under test, which can quickly reduce the parasitic inductance current to 0; while in this patent, the sum of the clamping capacitor voltage is close to the DC bus voltage, resulting in a longer time for the parasitic inductance current to drop to 0. During this period of time, the actual turn-off loss of the power device does not increase, but only charges the clamping capacitor, such as Figure 5 t2- If the traditional turn-off loss calculation method is used, that is:

[0062] ;

[0063] This will cause the measured turn-off loss to be significantly higher than the actual loss. Figure 5 As shown, as the power module under test is turned off, the voltage v of the clamping capacitor ci There will be a rise, and the clamping capacitor will be charged to a certain extent. This charging process will cause the measured value of the shutdown loss of the tested power module to be higher than the actual value, that is, the measured shutdown loss is significantly higher than the actual loss. At this time, if the shutdown loss of the power module is still determined according to the initial calculation relationship, there will be a significant error in the measurement result. Therefore, it is necessary to further determine the actual voltage and / or actual current of the capacitor when the power module is turned off to correct the shutdown loss. Specifically, considering the impact of the added capacitor in the test circuit on the test result of the shutdown loss, it is necessary to further determine the actual working electrical parameters of the capacitor during the test process to further correct the shutdown loss, avoid the impact of the capacitor on the test result of the shutdown loss, and improve the accuracy and reliability of the test results.

[0064] As an optional embodiment, the device-to-be-tested series module includes a plurality of main power devices connected in series and auxiliary power devices corresponding to the main power devices one by one, the double pulse test circuit includes capacitors connected in series corresponding to the respective auxiliary power devices of the device-to-be-tested series module, and the circuit after the auxiliary power devices and the capacitors are connected in series is connected in parallel with the corresponding main power devices; obtaining the working parameters during the opening and closing process of the device-to-be-tested series module includes:

[0065] When the main power device is turned off, the voltage across the series module of the device under test and the current flowing through the series module of the device under test are obtained;

[0066] When the main power device is turned off, the current of the loop where each capacitor is located and / or the voltage across each capacitor are obtained.

[0067] It can be understood that the working parameters of the series module of the device under test mainly include the voltage at both ends of the series module of the device under test and the current flowing through the series module of the device under test; at the same time, in order to subsequently correct the turn-off loss, it is also necessary to obtain the working parameters of the capacitor set in the double-pulse test circuit, including the current in the loop where each capacitor is located and the voltage at both ends of each capacitor, so as to facilitate the subsequent calculation and correction of the turn-off loss.

[0068] As an optional embodiment, the turn-off loss of the series module of the device under test is corrected based on the working parameters of the series module of the device under test and the working parameters of the double pulse test circuit, including:

[0069] Determine the current in the loop where any capacitor is located;

[0070] Determine the corrected turn-off loss of the device series module based on the current correction relationship between the current of the circuit where any capacitor is located and the turn-off loss;

[0071] The current correction relationship is:

[0072] ;

[0073] in, is the turn-off loss of the device series module, is the real-time value of the voltage across the device series module, t x t is the moment when the voltage across the device series module rises to 10% of the DC bus voltage rating during the shutdown process. y i is the moment when the current flowing through the device series module drops to 10% of the current rating during the shutdown process. d is the real-time value of the current flowing through the device series module, i a It is the real-time value of the current in the circuit where the capacitor is located.

[0074] On the one hand, the turn-off loss can be corrected according to the actual working current of the capacitor that has been re-determined. Since the turn-off loss error is caused by the charging process of the capacitor, it can be considered that the current actually flowing through the main power device = the current i flowing through the device series module d –Clamping capacitor loop current i a Therefore, the operating current i of the clamping capacitor can be measured by adding an additional current probe. a , when calculating i d Subtract i a After further integration, the actual turn-off loss of the series module Q1 of the device under test is: ; where i a It can be i a1 ,i a2 ,…,i aN Any one of them, that is, the working current of the circuit where any capacitor is located, can also be the average working current of the circuit where all capacitors are located, that is: i a =(i a1 +i a2 +…+i aN) / N. If you only need to determine the working current corresponding to any one capacitor, you only need to add a current probe, which is simple to implement and low in cost; if the average value of the working currents corresponding to all capacitors is used to determine it, it is necessary to add N current probes connected to each capacitor one by one, and the test results obtained are more accurate. Both schemes can effectively realize the correction process of the turn-off loss, and can be flexibly selected according to the actual application situation. The method for obtaining the working current of the capacitor includes but is not limited to the current probe method proposed in this embodiment. The specific type and implementation method of the current probe are not particularly limited in this application.

[0075] Specifically, the test error of the turn-off loss is caused by the charging process of the capacitor, so the current used in calculating the turn-off loss can be corrected by determining the charging current when the capacitor is charged, thereby realizing the correction process of the turn-off loss.

[0076] As an optional embodiment, the turn-off loss of the series module of the device under test is corrected based on the working parameters of the series module of the device under test and the working parameters of the double pulse test circuit, including:

[0077] Determine the voltage across any capacitor;

[0078] Determine the corrected turn-off loss of the device series module based on the voltage across any capacitor and the voltage correction relationship of the turn-off loss;

[0079] The voltage correction relationship is:

[0080] ;

[0081] in, is the turn-off loss of the device series module, is the real-time value of the voltage across the device series module, t x t is the moment when the voltage across the device series module rises to 10% of the DC bus voltage rating during the shutdown process. y i is the moment when the current flowing through the device series module drops to 10% of the current rating during the shutdown process. d is the real-time value of the current flowing through the device series module, N is the number of capacitors in the device series module, C is the capacitance of the capacitor, is the stable voltage value of the capacitor after the device series module is turned off, It is the stable voltage value of the capacitor when the device series module is turned on.

[0082] On the other hand, the turn-off loss can be corrected according to the actual working voltage of the re-determined capacitor. Since the turn-off loss error is caused by the charging process of the capacitor, the charging process of the capacitor will also be reflected in the change of the voltage across the capacitor. Therefore, the clamping capacitor voltage can be measured by adding a voltage probe, and the turn-off loss of the device series module under test = calculated loss - energy stored in the clamping capacitor, that is, Specifically, a voltage probe is used to measure v c1 -v cN Any waveform v ci To get the voltage change of any capacitor, V a and V b Yes ci The stable voltage value before the main power device is turned off (between t1 and t2) and after it is turned off (between t2' and t3). To make the result accurate, select V a 、V b The timing needs to avoid the switch spikes.

[0083] Furthermore, in order to make the turn-off loss test result more accurate, N voltage probes can be added to obtain v c1 -v cN All waveforms are used to determine the voltage changes corresponding to all capacitors. The corrected turn-off loss of the module under test is: ; where V ai and V bi Yes ci The stable voltage value before the main power device is turned off (between t1 and t2) and after it is turned off (between t2' and t3). To make the result accurate, select V ai and V bi The time point needs to avoid the switch spike. Both solutions can effectively realize the correction process of the turn-off loss, and can be flexibly selected according to the actual application situation. The method of obtaining the stored energy of the capacitor includes but is not limited to the voltage probe method proposed in this embodiment. The specific type and implementation method of the voltage probe are not particularly limited in this application.

[0084] Specifically, the test error of the turn-off loss is caused by the charging process of the capacitor. Therefore, the energy stored in the capacitor during the charging process can be determined by determining the voltage change when the capacitor is charged, thereby realizing the correction process of the turn-off loss.

[0085] In a second aspect, the present invention further provides a test circuit for a device series module, comprising a controller and a device series module Q1 to be tested, wherein the device series module Q1 to be tested comprises a plurality of main power devices connected in series and auxiliary power devices corresponding one to one to the main power devices, wherein the double pulse test circuit comprises capacitors connected in series one to one to the respective auxiliary power devices of the device series module, wherein the circuit after the auxiliary power devices and the capacitors are connected in series is connected in parallel to the corresponding main power devices, and the control ends of the main power devices and the auxiliary power devices are both connected to the controller;

[0086] The controller is used to implement the aforementioned turn-off loss test method for the device series module.

[0087] For an introduction to a test circuit of a device series module provided by the present invention, please refer to the embodiment of the above-mentioned device series module turn-off loss test method, and the present invention will not be repeated here.

[0088] As an optional embodiment, it further includes a discharge resistor R0 and a bus capacitor Cin, the discharge resistor R0 and the bus capacitor Cin are connected in parallel, and two ends of the parallel circuit are respectively connected to two ends of the DC bus.

[0089] It is not difficult to understand that, in order to facilitate the test of the final discharge process of the capacitor, a discharge resistor R0 connected in parallel at both ends of the DC bus is also added to the test circuit to speed up the discharge speed of the capacitor. At the same time, a bus capacitor Cin connected in parallel at both ends of the DC bus can also be set, and the bus capacitor Cin can play a filtering role. The specific type and implementation method of the discharge resistor R0 and the bus capacitor Cin are not particularly limited in this application.

[0090] Furthermore, in the pre-charging stage, the DC bus voltage V dc The capacitors C1-CN are charged via the freewheeling inductor L1 and the anti-parallel diodes of the auxiliary power devices Sa1-SaN. dc When it rises slowly, the charging process will not have a large current, and when V dc When the rated voltage suddenly increases from 0V to 3.6kV, the charging process may generate a large current. At this time, a contactor and a pre-charging resistor can be further added to the charging circuit. The pre-charging resistor is connected in series in the charging circuit, and the contactor is connected in parallel at both ends of the pre-charging resistor. During the charging process, the contactor is turned off to limit the charging current using the pre-charging resistor. After charging is completed, the contactor is closed to bypass the pre-charging resistor. The specific types and implementation methods of the contactor and the pre-charging resistor are not specifically limited in this application.

[0091] Specifically, the test circuit can also flexibly add circuit structures according to actual application conditions, which has high flexibility and a wide range of applications. The entire circuit structure is simple and easy to implement, which is conducive to the simple implementation of the entire test circuit.

[0092] As an optional embodiment, the output end of the controller is also connected to the control end of the double pulse test circuit, and the controller is also used to control the start and stop of the double pulse test circuit.

[0093] It is not difficult to understand that the entire test process needs to be carried out based on the start-up of the double pulse test circuit, so the controller can also control the start and stop of the double pulse test circuit. Controlling the start and stop of the double pulse test circuit specifically refers to controlling the opening or closing of the upper tube and the lower tube in the double pulse test circuit, that is, the start and stop of the double pulse test circuit is achieved by controlling the opening or closing of the freewheeling power device Q2 and the series module Q1 of the device under test.

[0094] Please refer to Figure 7 , Figure 7 A schematic diagram of the structure of an electronic device provided by the present invention. In a third aspect, the present invention further provides an electronic device, comprising:

[0095] A memory 21, used for storing computer programs;

[0096] The processor 22 is used to implement the steps of the aforementioned method for testing the turn-off loss of a device series module.

[0097] Among them, the processor 22 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 22 can be implemented in at least one hardware form of DSP (Digital Signal Processor), FPGA (Field-Programmable Gate Array), and PLA (Programmable Logic Array). The processor 22 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a central processing unit; the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 22 may integrate a GPU (graphics processing unit), which is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 22 may also include an AI (Artificial Intelligence) processor, which is used to process computing operations related to machine learning.

[0098] The memory 21 may include one or more computer-readable storage media, which may be non-transitory. The memory 21 may also include a high-speed random access memory, and a non-volatile memory, such as one or more disk storage devices, flash memory storage devices. In this embodiment, the memory 21 is at least used to store the following computer program, wherein, after the computer program is loaded and executed by the processor 22, it can implement the relevant steps of the turn-off loss test method of the device series module disclosed in any of the aforementioned embodiments. In addition, the resources stored in the memory 21 may also include an operating system and data, etc., and the storage method may be temporary storage or permanent storage. Among them, the operating system may include Windows, Unix, Linux, etc. The data may include but is not limited to the data of the turn-off loss test method of the device series module, etc.

[0099] In some embodiments, the electronic device may further include a display screen, an input and output interface, a communication interface, a power supply, and a communication bus.

[0100] It can be understood by those skilled in the art that Figure 7 The structure shown in the figure does not constitute a limitation on the electronic device, and may include more or fewer components than shown in the figure.

[0101] For an introduction to an electronic device provided by the present invention, please refer to the embodiment of the above-mentioned method for testing the turn-off loss of a device series module, and the present invention will not be described in detail here.

[0102] In a fourth aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the aforementioned method for testing the turn-off loss of a device series module.

[0103] It is understandable that if the method in the above embodiment is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium to execute all or part of the steps of the method described in each embodiment of the present application. Specifically, the computer-readable storage medium may include but is not limited to any type of disk, including a floppy disk, an optical disk, and a mobile hard disk, or any type of medium or device suitable for storing instructions, data, etc., and the present application does not make any special restrictions here.

[0104] For an introduction to a computer-readable storage medium provided by the present invention, please refer to the embodiment of the above-mentioned method for testing the turn-off loss of a device series module, and the present invention will not be repeated here.

[0105] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0106] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0107] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0108] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for testing the turn-off loss of a device series module, characterized in that: The device-to-be-tested series module is arranged in a double-pulse test circuit; The turn-off loss test method of the device series module includes: Starting the double pulse test circuit to control the turning on and off of each main power device in the series module of the device under test; Obtaining operating parameters during the opening and closing process of the series module of the device under test; The turn-off loss of the series module of the device under test is determined based on the operating parameters of the series module of the device under test.

2. The method for testing the turn-off loss of a device series module according to claim 1, characterized in that: After determining the turn-off loss of the series module of the device under test based on the operating parameters of the series module of the device under test, the method further includes: The turn-off loss of the series module of the device under test is corrected based on the operating parameters of the series module of the device under test and the operating parameters of the double pulse test circuit.

3. The method for testing the turn-off loss of a device series module according to claim 2, characterized in that: The device series module to be tested includes a plurality of main power devices connected in series and auxiliary power devices corresponding to the main power devices one by one, the double pulse test circuit includes capacitors connected in series with the auxiliary power devices of the device series module one by one, and the circuit after the auxiliary power devices and the capacitors are connected in series is connected in parallel with the corresponding main power devices; obtaining the working parameters during the opening and closing process of the device series module to be tested, including: When the main power device is turned off, the voltage across the series module of the device under test and the current flowing through the series module of the device under test are obtained; When the main power device is turned off, the current of the loop where each capacitor is located and / or the voltage across both ends of each capacitor are obtained.

4. The method for testing the turn-off loss of a device series module according to claim 3, characterized in that: Correcting the turn-off loss of the series module of the device under test based on the operating parameters of the series module of the device under test and the operating parameters of the double pulse test circuit, including: Determine the current of any one of the capacitor circuits; Determine the corrected turn-off loss of the device series module based on a current correction relationship between the current of any one of the capacitor loops and the turn-off loss; The current correction relationship is: ； in, is the turn-off loss of the device series module, is the real-time value of the voltage across the device series module, t x is the moment when the voltage across the device series module rises to 10% of the rated DC bus voltage during the shutdown process, t y is the moment when the current flowing through the device series module during the shutdown process drops to 10% of the current rating, i d is the real-time value of the current flowing through the device series module, i a It is the real-time value of the current in the loop where the capacitor is located.

5. The method for testing the turn-off loss of a device series module according to claim 3, characterized in that: Correcting the turn-off loss of the series module of the device under test based on the operating parameters of the series module of the device under test and the operating parameters of the double pulse test circuit, including: determining a voltage across any one of the capacitors; Determine the corrected turn-off loss of the device series module based on the voltage across any one of the capacitors and the voltage correction relationship of the turn-off loss; The voltage correction relationship is: ； in, is the turn-off loss of the device series module, is the real-time value of the voltage across the device series module, t x is the moment when the voltage across the device series module rises to 10% of the rated DC bus voltage during the shutdown process, t y is the moment when the current flowing through the device series module during the shutdown process drops to 10% of the current rating, i d is the real-time value of the current flowing through the device series module, N is the number of capacitors in the device series module, C is the capacitance of the capacitor, is the stable voltage value of the capacitor after the device series module is turned off, It is the stable voltage value of the capacitor when the device series module is turned on.

6. A test circuit for a device series module, characterized in that: It comprises a controller and a device series module to be tested, wherein the device series module to be tested comprises a plurality of main power devices connected in series and auxiliary power devices corresponding to the main power devices one by one, the double pulse test circuit comprises capacitors connected in series one by one with the auxiliary power devices of the device series module, the circuit after the auxiliary power devices and the capacitors are connected in series is connected in parallel with the corresponding main power devices, and the control ends of the main power devices and the auxiliary power devices are both connected to the controller; The controller is used to implement the turn-off loss test method of the device series module as described in any one of claims 1 to 5.

7. The device series module test circuit according to claim 6, characterized in that: It also includes a discharge resistor and a bus capacitor, the discharge resistor and the bus capacitor are connected in parallel, and two ends of the parallel circuit are respectively connected to two ends of the DC bus.

8. The device series module test circuit according to claim 6, characterized in that: The output end of the controller is also connected to the control end of the double pulse test circuit, and the controller is also used to control the start and stop of the double pulse test circuit.

9. An electronic device, characterized in that: include: Memory for storing computer programs; A processor, used to implement the steps of the method for testing the turn-off loss of a device series module as described in any one of claims 1 to 5.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the turn-off loss test method of the device series module according to any one of claims 1 to 5 are implemented.

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