Dual-Pulse Testing Method for Three-Phase Conversion Circuit, Three-Phase Converter and Wind Power Inverter

Abstract

The present application provides a dual-pulse test method for a three-phase conversion circuit, a three-phase converter, and a wind power converter. Since by controlling the on and off of the switching tubes in the three-phase conversion circuit, a test loop can be constructed for the switching tubes to be tested, and the control of the on and off of the switching tubes in the three-phase conversion circuit can be implemented by software, the dual-pulse test method improves the test speed of the dual-pulse test. Therefore, the dual-pulse test method for the three-phase conversion circuit provided by the present application can improve the test efficiency of the dual-pulse test on the three-phase conversion circuit; in addition, in this dual-pulse test method, the dual-pulse test can be performed on each switching tube without disassembling the conversion circuit. Therefore, this dual-pulse test method can perform the dual-pulse test on each switching tube in the conversion circuit online, thus saving a large amount of repetitive mechanical operations, and further improving the test efficiency of the dual-pulse test on the conversion circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a double-pulse testing method for a three-phase conversion circuit, a three-phase converter and a wind power converter. Background Art

[0002] Before a three-phase converter leaves the factory, it is necessary to perform a double-pulse test on each power device in the three-phase converter to improve the reliability of the three-phase converter. Currently, most three-phase converters are two-level, so under normal circumstances, each power device in the three-phase converter is subjected to an offline double-pulse test, that is, before the three-phase converter is assembled, the power devices are subjected to a double-pulse test.

[0003] Currently, three-level three-phase converters are widely used. Compared to two-level three-phase converters, the main circuit is a three-level three-phase converter instead of a two-level three-phase converter. This results in a more complex structure and includes more power devices. Therefore, if the aforementioned test method is still used for double-pulse testing, the test workload will increase dramatically, reducing the efficiency of double-pulse testing of three-level three-phase converter circuits.

[0004] Therefore, how to improve the test efficiency of double-pulse testing on three-phase conversion circuits is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] In view of this, the present invention provides a double-pulse test method for a three-phase conversion circuit, a three-phase converter, and a wind power converter to improve the test efficiency of the double-pulse test on the three-phase conversion circuit.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] A first aspect of the present application provides a double-pulse test method for a three-phase conversion circuit, comprising:

[0008] Charging each DC side capacitor in the three-phase conversion circuit to a preset voltage, and short-circuiting each AC port of the three-phase conversion circuit in pairs;

[0009] Each switch tube in the three-phase conversion circuit is sequentially used as a switch tube under test, and after each switch tube is used as the switch tube under test, a test loop is constructed for the switch tube under test by controlling the conduction of the corresponding switch tube in the three-phase conversion circuit;

[0010] After each test loop is constructed, a double pulse signal is input to the control terminal of the switch tube under test, and the change of each inductor current of the three-phase conversion circuit during this period is sampled;

[0011] After each sampling is completed, each of the switch tubes is turned off respectively.

[0012] Optionally, by controlling the conduction of the corresponding switching tubes in the three-phase conversion circuit, a test loop is constructed for the switching tube to be measured, including:

[0013] Determine each of the switching tubes that need to be conducted when constructing the test loop according to the switching tube to be measured;

[0014] Conduct each of the switching tubes that need to be conducted when constructing the test loop respectively.

[0015] Optionally, if the three-phase conversion circuit is a three-level conversion circuit, determining each of the switching tubes that need to be conducted when constructing the test loop according to the switching tube to be measured includes:

[0016] Judge whether the switching tube to be measured is the outer tube of its own half-bridge arm;

[0017] If the switching tube to be measured is the outer tube of its own half-bridge arm, then determining each of the switching tubes that need to be conducted when constructing the test loop includes: the inner tube of the half-bridge arm where the switching tube to be measured is located, and the inner tubes of the target half-bridge arm in another phase bridge arm or two other phase bridge arms;

[0018] If the switching tube to be measured is the inner tube of its own half-bridge arm, then determining each of the switching tubes that need to be conducted when constructing the test loop includes: the inner and outer tubes of the target half-bridge arm in another phase bridge arm or two other phase bridge arms;

[0019] Wherein, the inner tube is the switching tube connected to the inductor in the half-bridge arm, the outer tube is the switching tube connected to the DC bus in the half-bridge arm, and the target half-bridge arm is the half-bridge arm located on the different side from the half-bridge arm where the switching tube to be measured is located.

[0020] Optionally, if the switching tube to be measured is the outer tube of its own half-bridge arm, conducting each of the switching tubes that need to be conducted when constructing the test loop respectively includes:

[0021] Except for the inner tube of the half-bridge arm where the switching tube to be measured is located, conduct the other switching tubes that need to be conducted when constructing the test loop simultaneously;

[0022] After waiting for the first preset time, conduct the inner tube of the half-bridge arm where the switching tube to be measured is located.

[0023] Optionally, if the switching tube to be measured is the inner tube of its own half-bridge arm, conducting each of the switching tubes that need to be conducted when constructing the test loop respectively includes:

[0024] Conduct the switching tubes that need to be conducted when constructing the test loop simultaneously.

[0025] Optionally, it further includes:

[0026] After each sampling is completed, each of the switching tubes is turned off respectively.

[0027] Optionally, if the three-phase conversion circuit is a three-level conversion circuit and the switching tube to be measured is the outer tube of its own half-bridge arm, turning off each of the switching tubes respectively includes:

[0028] Turn off the inner tube of the half-bridge arm where the switching tube to be measured is located;

[0029] After waiting for a second preset time, turn off simultaneously each of the remaining switching tubes in the conducting state;

[0030] If the switching tube to be measured is the inner tube of its own half-bridge arm, turning off each of the switching tubes respectively includes:

[0031] Turn off simultaneously each of the switching tubes in the conducting state.

[0032] Optionally, it further includes:

[0033] After each sampling is completed, according to the sampling result, obtain the test result of the switching tube serving as the switching tube to be measured;

[0034] Or,

[0035] After all samplings are completed, according to each sampling result, obtain the test results of each of the switching tubes serving as the switching tube to be measured respectively.

[0036] Optionally, analyzing the test result of the switching tube serving as the switching tube to be measured according to the sampling result includes:

[0037] Judge whether the maximum value of the sampling result exceeds a preset value or is equal to zero;

[0038] If the maximum value of the sampling result does not exceed the preset value and is not equal to zero, it is determined that the switching tube serving as the switching tube to be measured is not failed;

[0039] If the maximum value of the sampling result exceeds the preset value or is equal to zero, it is determined that the switching tube serving as the switching tube to be measured is failed.

[0040] Optionally, after obtaining the test results of each of the switching tubes serving as the switching tube to be measured respectively, it further includes:

[0041] Judge whether each of the switching tubes is not failed;

[0042] If each of the switching tubes is not failed, discharge each DC-side capacitor in the three-phase conversion circuit to zero voltage and disconnect the short circuit between each AC port of the three-phase conversion circuit;

[0043] If at least one of the switching tubes fails, the tester is notified to replace the failed switching tube.

[0044] The second aspect of the present application provides a three-phase converter, including: a three-phase conversion circuit and a controller; where:

[0045] The controller is respectively connected to the control ends of the switching tubes in the three-phase conversion circuit, and is configured to execute the double-pulse test method of the three-phase conversion circuit as described in any one of the first aspects of the present application.

[0046] Optionally, it further includes: a switching device; where:

[0047] The connection ports on one side of the switching device are respectively connected to the AC ports of the three-phase conversion circuit, and the connection ports on the other side of the switching device are all connected;

[0048] The switching device is controlled by the controller and is configured to short-circuit the AC ports in pairs.

[0049] Optionally, the switching device is a contactor, and one ends of the normally open contacts in the contactor are respectively connected to the AC ports of the three-phase conversion circuit, and the other ends of the normally open contacts in the contactor are all connected.

[0050] Optionally, the switching tubes in the three-phase conversion circuit are insulated gate bipolar transistors IGBTs, integrated gate-commutated thyristors IGCTs, or gate-injected enhanced transistors IEGTs.

[0051] The third aspect of the present application provides a wind power converter, including: a controller, a machine-side converter, and a grid-side converter; where:

[0052] The DC side of the machine-side converter is connected to the DC side of the grid-side converter;

[0053] The main circuits of the machine-side converter and the grid-side converter are both three-phase conversion circuits;

[0054] The controller is respectively connected to the control ends of the switching tubes in each of the three-phase conversion circuits, and is configured to sequentially execute the double-pulse test method of the three-phase conversion circuit as described in any one of the first aspects of the present application on the machine-side converter and the grid-side converter.

[0055] Optionally, it further includes: two switching devices; where:

[0056] The switching devices correspond to the three-phase conversion circuits one by one;

[0057] Each connection port on one side of the switching device is respectively connected to each AC port of the corresponding three-phase conversion circuit, and all connection ports on the other side of the switching device are connected together;

[0058] The switching device is controlled by the controller and is used to short-circuit each pair of the AC ports.

[0059] Optionally, the switching device is a contactor. One end of each normally open contact in the contactor is respectively connected to each AC port of the corresponding three-phase conversion circuit, and the other ends of all the normally open contacts in the contactor are connected together.

[0060] Optionally, if both of the two switching devices are contactors, then the normally closed contact in each contactor is arranged between the relay in the other contactor and the AC power supply.

[0061] Optionally, the controller is further used for:

[0062] When it is detected that all the AC terminals of the two three-phase conversion circuits are short-circuited in pairs, stop executing the dual-pulse test method of the three-phase conversion circuit.

[0063] Optionally, if the wind power converter includes two switching devices and both of the two switching devices are contactors, then the controller is further used for:

[0064] When it is detected that the normally open contacts of the two contactors are closed simultaneously, stop executing the dual-pulse test method of the three-phase conversion circuit.

[0065] Optionally, the switching tubes in the three-phase conversion circuit are insulated gate bipolar transistors (IGBTs), integrated gate-commutated thyristors (IGCTs), or gate-injected enhanced transistors (IEGTs).

[0066] Optionally, the controller is integrated in the main controller of the wind turbine unit connected to the wind power converter.

[0067] As can be seen from the above technical solutions, the present invention provides a dual-pulse test method for a three-phase conversion circuit. Since a test loop can be constructed for the switch tube to be tested by controlling the on / off of the switch tubes in the three-phase conversion circuit, and the on / off of the switch tubes in the three-phase conversion circuit can be realized by software, the dual-pulse test method improves the test speed of the dual-pulse test. Therefore, the dual-pulse test method for the three-phase conversion circuit provided in this application can improve the test efficiency of the dual-pulse test for the three-phase conversion circuit. In addition, in this dual-pulse test method, the dual-pulse test can be performed on each switch tube in the three-phase conversion circuit without disassembling the three-phase conversion circuit. Therefore, this dual-pulse test method can perform the dual-pulse test on each switch tube in the three-phase conversion circuit online, thus saving a large amount of repetitive mechanical operations, such as repeated assembly, and further improving the test efficiency of the dual-pulse test for the three-phase conversion circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0069] Figure 1 is a schematic structural diagram of a three-level three-phase conversion circuit;

[0070] Figure 2 is a schematic flowchart of the dual-pulse test method for the three-phase conversion circuit provided in the embodiment of the present application;

[0071] Figure 3a and Figure 3b are respectively two examples of dual-pulse signals;

[0072] Figure 4 is a schematic flowchart of an implementation manner for constructing a test loop for the switch tube to be tested provided in the embodiment of the present application;

[0073] Figure 5 is a schematic flowchart of an implementation manner of step S210 provided in the embodiment of the present application;

[0074] Figure 6a and Figure 6b are respectively schematic diagrams of the current flow directions on the test loop when the switch tube Sa1 is conducting and when the switch tube Sa1 is turned off;

[0075] Figure 7 is a schematic flowchart of an implementation manner of step S220 provided in the embodiment of the present application;

[0076] Figure 8When constructing a test circuit for the switch tube Sa1, Figure 1 Schematic diagram of the drive signals of each switch tube in

[0077] Figure 9a Schematic flow chart of another implementation manner of the dual-pulse test method for the three-phase conversion circuit provided by the embodiment of the present application;

[0078] Figure 9b Schematic flow chart of an implementation manner for separately turning off each switch tube provided by the embodiment of the present application;

[0079] Figure 10 and Figure 11 Schematic flow charts of another two implementation manners of the dual-pulse test method for the three-phase conversion circuit provided by the embodiment of the present application respectively;

[0080] Figure 12 Schematic flow chart of an implementation manner for analyzing the test result of the switch tube as the switch tube to be measured according to the sampling result provided by the embodiment of the present application;

[0081] Figure 13 Schematic flow chart of another implementation manner of the dual-pulse test method for the three-phase conversion circuit provided by the embodiment of the present application;

[0082] Figure 14 Another structural schematic diagram of the three-level three-phase converter;

[0083] Figures 15 - 18 Structural schematic diagrams of four implementation manners of the wind power converter provided by the embodiment of the present application respectively. Specific implementation manner

[0084] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present application.

[0085] In this application, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0086] In order to improve the test efficiency of the double-pulse test for a three-phase conversion circuit, an embodiment of this application provides a double-pulse test method for a three-phase conversion circuit. Among them, the three-phase conversion circuit is a mature circuit topology in the prior art, and can be, for example, Figure 1 the three-level three-phase conversion circuit shown as follows, which will not be elaborated in detail here.

[0087] The specific process of this double-pulse test method is as shown in Figure 2 and specifically includes the following steps:

[0088] S110: Charge each DC-side capacitor in the three-phase conversion circuit to a preset voltage, and short-circuit each pair of AC ports of the three-phase conversion circuit.

[0089] Among them, the preset voltage is preset according to the actual situation, and no specific limitation is made here, and all are within the protection scope of this application.

[0090] Taking Figure 1 the three-level three-phase conversion circuit shown as an example, the specific DC-side capacitors in the three-phase conversion circuit are: Figure 1 capacitor C1 and capacitor C2 in it. In addition, at this time, the connection point of capacitor C1 and capacitor C2 is the DC-side neutral point of the three-phase conversion circuit.

[0091] In practical applications, before charging each DC-side capacitor in the three-phase conversion circuit to the preset voltage, the three-phase conversion circuit can be first put into a stop state, and no specific limitation is made here, and all are within the protection scope of this application.

[0092] S120: Take each switch tube in the three-phase conversion circuit as the switch tube to be tested in turn, and after each switch tube is taken as the switch tube to be tested, build a test circuit for the switch tube to be tested by controlling the conduction of the corresponding switch tube in the three-phase conversion circuit.

[0093] S130. After each test loop is constructed, a double-pulse signal is input to the control terminal of the switch tube under test, and the changes in the inductor currents of each phase conversion circuit during this period are sampled.

[0094] Among them, the double-pulse signal is a signal with two rising edges and two falling edges, which can be as Figure 3a shown, and can be as Figure 3b shown; no specific limitation is made here, and it can be determined according to specific circumstances, and all are within the protection scope of this application.

[0095] In the double-pulse signal, the turn-off signal can be determined according to actual experience, and the duration of the turn-on signal is obtained by reverse deduction through the formula I = V dc *t / L.

[0096] Among them, I is the rated current value of the switch tube under test; V dc is the voltage difference between the positive pole of the DC side and the neutral point of the DC side of the three-phase conversion circuit, or the voltage difference between the neutral point of the DC side and the negative pole of the DC side of the three-phase conversion circuit; L is the total inductance in the test loop. For example, in the Figure 1 shown three-phase conversion circuit, when the switch tube Sa1 is the switch tube under test, L = the parallel inductance of inductor Ls2 and inductor L3 + inductor Ls1.

[0097] Since a test loop can be constructed for the switch tube under test by controlling the conduction of the corresponding switch tube in the three-phase conversion circuit, and the on-off of the switch tube in the three-phase conversion circuit can be realized by software, the double-pulse test method improves the test speed of the double-pulse test. Therefore, the double-pulse test method for the three-phase conversion circuit provided by this application can improve the test efficiency of the double-pulse test for the three-phase conversion circuit; in addition, in this double-pulse test method, the double-pulse test can be performed on each switch tube in the three-phase conversion circuit without disassembling the three-phase conversion circuit. Therefore, this double-pulse test method can perform the double-pulse test on each switch tube in the three-phase conversion circuit online, thus saving a large amount of repetitive mechanical operations, such as repeated assembly, and further improving the test efficiency of the double-pulse test for the three-phase conversion circuit.

[0098] Another embodiment of this application provides a specific implementation manner for constructing a test loop for the switch tube under test. The specific process is as Figure 4 shown, and specifically includes the following steps:

[0099] S210. Determine each switch tube that needs to be turned on when constructing the test loop according to the switch tube under test.

[0100] S220. Turn on each switch tube that needs to be turned on when constructing the test loop respectively.

[0101] This embodiment provides a specific implementation manner of step S210, and its specific process is as follows Figure 5 shown, and specifically includes the following steps:

[0102] S310. Determine whether the switch tube under test is the outer tube of the half-bridge arm where it is located.

[0103] If the switch tube under test is the outer tube of the half-bridge arm where it is located, then execute step S320; if the switch tube under test is the inner tube of the half-bridge arm where it is located, that is, the switch tube under test is not the outer tube of the half-bridge arm where it is located, then execute step S330.

[0104] Among them, the inner tube is the switch tube connected to the inductor in the half-bridge arm, such as Figure 1 Sa2, Sa3, Sb2, Sb3, Sc2, Sc3 in Figure 1 The outer tube is the switch tube connected to the DC bus in the half-bridge arm, such as

[0105] Sa1, Sa4, Sb1, Sb4, Sc1, Sc4 in

[0106] Among them, the target half-bridge arm is the half-bridge arm on the different side from the half-bridge arm where the switch tube under test is located; for example, if the switch tube under test is in the upper half-bridge arm, the target half-bridge arm is the lower half-bridge arm.

[0107] S330. Determine that the switch tubes that need to be turned on when constructing the test circuit include: the inner tube and the outer tube of the target half-bridge arm in another phase bridge arm or the other two phase bridge arms.

[0108] Taking Figure 1 the three-level three-phase conversion circuit shown as an example, if all three-phase bridge arms are utilized when constructing the test circuit, then when Figure 1 the 12 switch tubes in the three-level three-phase conversion circuit shown are respectively used as the switch tubes under test, the on-off conditions of the remaining switch tubes in the three-phase conversion circuit are as shown in the following table:

[0109]

[0110] Among them, △ indicates that the corresponding switch tube is the switch tube under test, 0 indicates that the corresponding switch tube is turned off, and 1 indicates that the corresponding switch tube is turned on.

[0111] Taking the switch tube Sa1 as the switch tube under test as an example, the test circuit is described as follows:

[0112] As can be seen from the above table, when the switching transistor Sa1 is the switching transistor to be measured, the switching transistors Sa2, Sb3, and Sc3 are all turned on. At this time, the constructed test circuit includes: the switching transistor Sa2, the switching transistor Sb3, the switching transistor Sc3, the inductor Ls1, the inductor Ls2, and the inductor Ls3.

[0113] When the switching transistor Sa1 is turned on, as Figure 6a shown, the current flow is: Vdc+ → Sa1 → Sa2 → Ls1 → Ls2 → Sb2 → Db2 → O, and, Vdc+ → Sa1 → Sa2 → Ls1 → Ls3 → Sc3 → Dc2 → O.

[0114] When the switching transistor Sa1 is turned off, as Figure 6b shown, the current flow is: Ls2 → Sb2 → Db2 → O → Da1 → Sa2 → Ls1 → Ls2, Ls3 → Sc3 → Dc2 → O → Da1 → Sa2 → Ls1 → Ls3.

[0115] Another embodiment of the present application provides a specific implementation manner of step S220, which is applicable to the case where the switching transistor to be measured is the outer transistor of the half-bridge arm where it is located. The specific process of this implementation manner is as Figure 7 shown, and specifically includes the following steps:

[0116] S410: Except for the inner transistor of the half-bridge arm where the switching transistor to be measured is located, turn on all the other switching transistors that need to be turned on when constructing the test circuit at the same time.

[0117] S420: After waiting for the first preset time, turn on the inner transistor of the half-bridge arm where the switching transistor to be measured is located.

[0118] Among them, the first preset time is set according to the actual situation, and no specific limitation is made here, and all are within the protection scope of the present application.

[0119] Still taking the switching transistor Sa1 in the three-level conversion circuit shown in Figure 1 as an example of the switching transistor to be measured, when constructing a test circuit for the switching transistor Sa1, first turn on the switching transistors Sb3 and Sc3, and then turn on the switching transistor Sa2 after waiting for a period of time; among them, the drive signals of each switching transistor are as Figure 8 shown.

[0120] It should be noted that the above is only one implementation manner of step S220 in this case. In actual applications, including but not limited to this, for example, all the switching transistors that need to be turned on when constructing the test circuit can also be turned on at the same time. No specific limitation is made here, and it can be determined according to the specific situation, and all are within the protection scope of the present application.

[0121] This embodiment also provides another specific implementation of S220, which is applicable to the case where the switch tube under test is the inner tube of its own half-bridge arm. This implementation is specifically as follows: Turn on all the switch tubes that need to be turned on when constructing the test circuit simultaneously.

[0122] It should be noted that the above is only one implementation of step S220 in this case. In actual applications, including but not limited to this, for example, the switch tubes that need to be turned on when constructing the test circuit can also be turned on successively. No specific limitation is made here and it can be determined according to specific circumstances, and all are within the protection scope of this application.

[0123] Another embodiment of this application provides another implementation of the dual-pulse test method for the three-phase conversion circuit. Its specific process can be referred to Figure 9a (only shown on the basis of Figure 2 . On the basis of the above embodiment, after step S130, the following steps are further included:

[0124] S140. After each sampling is completed, turn off each switch tube separately.

[0125] This embodiment provides a specific implementation of turning off each switch tube separately, which is applicable to the case where the switch tube under test is the outer tube of its own half-bridge arm. The specific process of this implementation is as Figure 9b shown, and specifically includes the following steps:

[0126] S510. Turn off the inner tube of the half-bridge arm where the switch tube under test is located.

[0127] S520. After waiting for the second preset time, turn off all the remaining switch tubes that are in the on state simultaneously.

[0128] Still taking the switch tube Sa1 in the three-level conversion circuit shown in Figure 1 as an example of the switch tube under test. After the sampling of the test circuit of the switch tube Sa1 is completed, first turn off the switch tube Sa2, and then turn off the switch tubes Sb3 and Sc3 after waiting for a period of time; among them, the drive signals of each switch tube are as Figure 8 shown.

[0129] It should be noted that the above is only one implementation of turning off each switch tube separately in this case. In actual applications, including but not limited to this, for example, all the switch tubes in the on state can also be turned off simultaneously. No specific limitation is made here and it can be determined according to specific circumstances, and all are within the protection scope of this application.

[0130] This embodiment also provides another specific implementation manner for separately turning off each switching tube, which is applicable to the case where the switching tube to be measured is the inner tube of its own half-bridge arm. Specifically, this implementation manner is as follows: simultaneously turning off each switching tube that is in the conducting state.

[0131] It should be noted that the above is only one implementation manner for separately turning off each switching tube in this case. In actual applications, including but not limited to this, for example, each switching tube that is in the conducting state can also be turned off successively. No specific limitation is made here, and it can be determined according to specific situations, and all are within the protection scope of this application.

[0132] Another embodiment of this application also provides another two specific implementation manners for the dual-pulse test method of the three-phase conversion circuit.

[0133] The specific structure of the first implementation manner is as Figure 10 (shown only on the basis of Figure 2 ) shown. On the basis of the above implementation manner, the following steps are further included:

[0134] S610. After each sampling is completed, according to the sampling result, obtain the test result of the switching tube that serves as the switching tube to be measured.

[0135] The specific structure of the second implementation manner is as Figure 11 (shown only on the basis of Figure 2 ) shown. On the basis of the above implementation manner, the following steps are further included:

[0136] S710. After all samplings are completed, according to each sampling result, obtain the test results of the respective switching tubes that serve as the switching tubes to be measured.

[0137] It should be noted that the above two implementation manners can be determined according to specific situations. No specific limitation is made here, and all are within the protection scope of this application.

[0138] This embodiment also provides a specific implementation manner for analyzing the test result of the switching tube that serves as the switching tube to be measured according to the sampling result. The specific process of this implementation manner is as Figure 12 shown, and specifically includes the following steps:

[0139] S810. Determine whether the maximum value of the sampling result exceeds a preset value or is equal to zero.

[0140] If the maximum value of the sampling result does not exceed the preset value and is not equal to zero, then execute step S820; if the maximum value of the sampling result exceeds the preset value or is equal to zero, then execute step S830.

[0141] Among them, the preset value is a value preset according to the actual situation. No specific limitation is made here, and all are within the protection scope of this application.

[0142] S820. Determine that the switching device to be measured, i.e., the switching transistor, has not failed.

[0143] S830. Determine that the switching device to be measured, i.e., the switching transistor, has failed.

[0144] It should be noted that the above embodiments are relatively mature technologies in the prior art and will not be elaborated here. In addition, the above embodiments are only one way to analyze the test results of the switching device to be measured, i.e., the switching transistor, according to the sampling results in the prior art. In actual applications, including but not limited to this, no specific limitations are made here and it can be determined according to specific circumstances, all within the protection scope of this application.

[0145] In this embodiment, according to each sampling result, the test results of each switching device to be measured, i.e., each switching transistor, can be analyzed, so that the failed switching transistor can be effectively located, facilitating the tester to replace the failed switching transistor.

[0146] Another embodiment of this application provides another implementation of the dual-pulse test method for a three-phase conversion circuit. The specific process of this implementation is as Figure 13 (shown only by taking Figure 10 as an example). On the basis of the above embodiment, after obtaining the test results of each switching device to be measured, i.e., each switching transistor, the following steps are further included:

[0147] S910. Determine whether all the switching transistors have not failed.

[0148] If all the switching transistors have not failed, then execute step S920; if at least one switching transistor has failed, then execute step S930.

[0149] S920. Discharge all the DC-side capacitors in the three-phase conversion circuit to zero voltage and disconnect the short circuit between the AC ports of the three-phase conversion circuit.

[0150] It should be noted that after disconnecting the short circuit between the AC ports of the three-phase conversion circuit, when a start command is received, the three-phase conversion circuit can be controlled to start.

[0151] S930. Notify the tester to replace the failed switching transistor.

[0152] Another embodiment of this application provides a three-phase converter, which specifically includes: a three-phase conversion circuit and a controller; among them, the three-phase conversion circuit is a mature circuit topology in the prior art, such as Figure 1 the three-level three-phase conversion circuit shown, which will not be elaborated in detail here.

[0153] The connection relationship between each device is as described below:

[0154] The controller is respectively connected to the control ends of the switching tubes in the three-phase conversion circuit.

[0155] During operation, the controller is used to execute the dual-pulse test method for the three-phase conversion circuit provided in the above embodiment; the dual-pulse test method for the three-phase conversion circuit has been described in detail in the above embodiment and will not be elaborated here.

[0156] Optionally, the controller collects the changes in the inductor currents of each phase in the three-phase conversion circuit through current sensors; in practical applications, including but not limited to this, specific limitations are not made here and it can be determined according to specific circumstances, all within the protection scope of this application.

[0157] This embodiment also provides another implementation manner of the three-phase converter, and its specific structure can be referred to Figure 14 (the controller is not shown in the figure), in the above implementation manner, it further includes: a switching device 10; the connection relationship between the switching device 10 and other devices is described as follows:

[0158] The respective connection ports on one side of the switching device 10 are respectively connected to the respective AC ports of the three-phase conversion circuit, the respective connection ports on the other side of the switching device 10 are all connected, and the control end of the switching device 10 is connected to the controller.

[0159] During operation, the switching device 10 short-circuits the respective AC ports in pairs under the control of the controller.

[0160] It should be noted that adding the switching device 10 is only a specific implementation manner for short-circuiting the respective AC ports in pairs. In practical applications, including but not limited to this, specific limitations are not made here and it can be determined according to specific circumstances, all within the protection scope of this application.

[0161] Preferably, the switching device 10 is a contactor; specifically, one end of each normally open contact in the contactor is respectively connected to the respective AC ports of the three-phase conversion circuit, and the other ends of each normally open contact in the contactor are all connected.

[0162] In practical applications, the implementation manner of the switching device 10 includes but is not limited to the above implementation manner. Specific limitations are not made here and it can be determined according to specific circumstances, all within the protection scope of this application.

[0163] Optionally, the switching devices in the three-phase conversion circuit may be IGBTs (Insulated Gate Bipolar Transistors), or IGCTs (Integrated Gate-Commutated Thyristors), or IEGTs (Injection Enhanced Gate Transistors); in practical applications, including but not limited to this, no specific limitation is made here, and it can be determined according to specific circumstances, and all are within the protection scope of this application.

[0164] Another embodiment of this application provides a wind power converter, and its specific structure is as Figure 15 (the controller is not shown in the figure), and specifically includes: a controller, a machine-side converter 100, and a grid-side converter 200; among them, the main circuits of the machine-side converter 100 and the grid-side converter 200 are both three-phase conversion circuits.

[0165] The connection relationships between the devices are as described below:

[0166] The DC side of the machine-side converter 100 is connected to the DC side of the grid-side converter 200; the AC side of the machine-side converter 100 serves as the machine side of the wind power converter and is connected to the wind turbine; the AC side of the grid-side converter 200 serves as the AC side of the wind power converter and is connected to the power grid; the controller is respectively connected to the control terminals of the switching devices in each three-phase conversion circuit.

[0167] It should be noted that since the DC side of the machine-side converter 100 is connected to the DC side of the grid-side converter 200, and the main circuits of the machine-side converter 100 and the grid-side converter 200 are both three-phase conversion circuits, so in practical applications, the two capacitors C1 can be combined into one capacitor C1, and the two capacitors C2 can be combined into one capacitor C2, as Figure 15 shown.

[0168] During operation, the controller successively performs the double-pulse test method for the three-phase conversion circuit provided in the above embodiment on the machine-side converter 100 and the grid-side converter 200.

[0169] Optionally, the controller collects the changes in the inductor currents of the three-phase conversion circuit through current sensors; in practical applications, including but not limited to this, no specific limitation is made here, and it can be determined according to specific circumstances, and all are within the protection scope of this application.

[0170] This embodiment also provides another implementation manner of the wind power converter, and its specific structure is as Figure 16 shown. On the basis of the above implementation manner, it further includes: two switching devices 10; among them, the switching devices 10 correspond to the three-phase conversion circuits one by one.

[0171] The connection relationship between the switching device 10 and other devices is described as follows:

[0172] Each connection port on one side of each switching device 10 is respectively connected to each AC port of the corresponding three-phase conversion circuit. Each connection port on the other side of each switching device 10 is connected together, and the control end of each switching device 10 is connected to the controller.

[0173] During operation, each switching device 10 short-circuits each pair of AC ports under the control of the controller.

[0174] It should be noted that adding the switching device 10 is only a specific implementation manner for short-circuiting each pair of the said AC ports. In practical applications, including but not limited to this, no specific limitation is made here and it can be determined according to specific situations, all within the protection scope of this application.

[0175] Preferably, the switching device 10 is a contactor; specifically, one end of each normally open contact in the contactor is respectively connected to each AC port of the corresponding three-phase conversion circuit, and the other ends of each normally open contact in the contactor are connected together.

[0176] In practical applications, the implementation manner of the switching device 10 includes but is not limited to the above implementation manner. No specific limitation is made here and it can be determined according to specific situations, all within the protection scope of this application.

[0177] Optionally, the switching tube in the three-phase conversion circuit can be an IGBT (Insulated Gate Bipolar Transistor), or an IGCT (Integrated Gate-Commutated Thyristor), or an IEGT (Injection Enhanced Gate Transistor); in practical applications, including but not limited to this, no specific limitation is made here and it can be determined according to specific situations, all within the protection scope of this application.

[0178] Optionally, the controller can be integrated into the main controller in the wind turbine unit connected to the wind power converter, or can be independently set; in practical applications, including but not limited to this, no specific limitation is made here and it can be determined according to specific situations, all within the protection scope of this application.

[0179] Another embodiment of this application provides another implementation manner of the wind power converter. The specific structure of this implementation manner is as Figure 17 shown. This implementation manner is basically the same as the structure of the implementation manner shown in Figure 16 , the difference is:

[0180] In this embodiment, both of the two switching devices 10 are contactors, and the normally closed contacts in each contactor are arranged between the relay in the other contactor and the AC power supply, which is specifically described as follows:

[0181] The contactor connected to the machine-side converter is the first contactor, and the contactor connected to the grid-side converter is the second contactor. One end of each normally open contact K1.1 of the first contactor is respectively connected to each AC port of the machine-side converter, and the other ends of each normally open contact K1.1 of the first contactor are all connected. The AC power supply terminal of the relay KA1 of the first contactor is connected to the AC power supply VCC through the normally closed contact K2.2 of the second contactor. One end of each normally open contact K2.1 of the second contactor is respectively connected to each AC port of the grid-side converter, and the other ends of each normally open contact K2.1 of the second contactor are all connected. The AC power supply terminal of the relay KA2 of the second contactor is connected to the power grid VCC through the normally closed contact K1.2 of the first contactor.

[0182] Since the normally closed contacts in each contactor are arranged between the relay in the other contactor and the AC power supply, only when the normally open contact of one contactor is disconnected, that is, when the normally closed contact of this contactor is closed, can the normally open contact of the other contactor be closed. Therefore, under normal circumstances, only one of the normally open contacts of the two contactors can be closed, which realizes interlock at the hardware level, thus avoiding the controller from simultaneously performing double-pulse tests on the machine-side converter 100 and the grid-side converter 200, and further ensuring the effectiveness of the double-pulse test and improving the safety of the wind power converter, preventing damage to the wind power converter.

[0183] Another embodiment of the present application provides another two implementation manners of the wind power converter; the specific structure of the first implementation manner is basically the same as that of the implementation manner shown in Figure 15 The difference is that in this implementation manner, the controller detects each AC terminal of the two three-phase conversion circuits, and when it detects that each AC terminal of the two three-phase conversion circuits is short-circuited pairwise, it stops executing the double-pulse test method of the three-phase conversion circuit.

[0184] The specific structure of the second implementation manner is basically the same as that of the implementation manner shown in Figure 17 The difference is that in this implementation manner, the controller detects the normally closed contacts of the two contactors, and when it detects that the normally open contacts of the two contactors are closed simultaneously, it stops executing the double-pulse test method of the three-phase conversion circuit.

[0185] Among them, an example of the controller detecting the normally closed contacts of the two contactors is: as Figure 18As shown, a normally open contact K1.1 of a first contactor is arranged between an ARM in the controller and a DC power supply VDC, and a normally open contact K2.1 of a second contactor is arranged between another ARM in the controller and the DC power supply VDC. When the normally open contacts of the two contactors are closed simultaneously, the two ARMs are powered on simultaneously, and a fault signal is reported to the controller at this time.

[0186] The above is only an example of the controller detecting the normally closed contacts of the two contactors. In actual applications, it includes but is not limited to this, and no specific limitation is made here, and all are within the protection scope of this application.

[0187] In the above two embodiments, since in essence the controller stops executing the dual-pulse test method of the three-phase conversion circuit when the AC terminals of the two three-phase conversion circuits are short-circuited in pairs, the above two embodiments achieve interlocking at the software level, thereby avoiding the controller from simultaneously performing the dual-pulse test on the machine-side converter 100 and the grid-side converter 200. Furthermore, it not only ensures the effectiveness of the dual-pulse test but also improves the safety of the wind power converter and prevents damage to the wind power converter.

[0188] Regarding the above description of the disclosed embodiments, the features described in each embodiment of this specification can be replaced or combined with each other, enabling those skilled in the art to implement or use this application. The above are only preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A double-pulse test method for a three-phase conversion circuit, characterized in that, Including: Charging each DC-side capacitor in the three-phase conversion circuit to a preset voltage, and short-circuiting two by two each AC port of the three-phase conversion circuit; the three-phase conversion circuit is a three-level conversion circuit; Taking each switching tube in the three-phase conversion circuit as the measured switching tube in turn, and after each switching tube is taken as the measured switching tube, determining whether the measured switching tube is the outer tube of its own half-bridge arm; If the measured switching tube is the outer tube of its own half-bridge arm, then through software control, simultaneously turning on the other switching tubes that need to be turned on when constructing the test circuit except for the inner tube of the half-bridge arm where the measured switching tube is located, and after waiting for a first preset time, turning on the inner tube of the half-bridge arm where the measured switching tube is located; if the measured switching tube is the inner tube of its own half-bridge arm, then through software control, simultaneously turning on the switching tubes that need to be turned on when constructing the test circuit to construct a test circuit for the measured switching tube; After each test circuit is constructed, inputting a double-pulse signal to the control end of the measured switching tube, and sampling the changes in the inductor currents of each phase of the three-phase conversion circuit during this period.

2. The double-pulse test method for the three-phase conversion circuit according to claim 1, wherein If the measured switching tube is the outer tube of its own half-bridge arm, then the switching tubes that need to be turned on when constructing the test circuit include: the inner tube of the half-bridge arm where the measured switching tube is located, and the inner tubes of the target half-bridge arms in another phase bridge arm or the other two phase bridge arms; If the measured switching tube is the inner tube of its own half-bridge arm, then the switching tubes that need to be turned on when constructing the test circuit include: the inner tubes and outer tubes of the target half-bridge arms in another phase bridge arm or the other two phase bridge arms; Wherein, the inner tube is the switching tube connected to the inductor in the half-bridge arm, the outer tube is the switching tube connected to the DC bus in the half-bridge arm, and the target half-bridge arm is the half-bridge arm located on the different side from the half-bridge arm where the measured switching tube is located.

3. The double-pulse test method for the three-phase conversion circuit according to claim 1, characterized in that, It further includes: After each sampling is completed, turning off each switching tube separately.

4. The double-pulse test method for the three-phase conversion circuit according to claim 3, characterized in that, If the measured switching tube is the outer tube of its own half-bridge arm, turning off each switching tube separately includes: Turning off the inner tube of the half-bridge arm where the measured switching tube is located; After waiting for a second preset time, simultaneously turning off the other switching tubes in the conducting state; If the measured switching tube is the inner tube of its own half-bridge arm, turning off each switching tube separately includes: Simultaneously turning off the switching tubes in the conducting state.

5. The double-pulse test method for a three-phase conversion circuit according to any one of claims 1 to 4, characterized in that It further includes: After each sampling is completed, obtaining the test result of the switching tube as the measured switching tube according to the sampling result; Or, After all samplings are completed, obtaining the test results of the switching tubes as the measured switching tubes respectively according to each sampling result.

6. The dual-pulse test method for the three-phase conversion circuit according to claim 5, wherein Analyzing the test result of the switching tube as the measured switching tube according to the sampling result includes: Judging whether the maximum value of the sampling result exceeds a preset value or is equal to zero; If the maximum value of the sampling result does not exceed the preset value and is not equal to zero, then determining that the switching tube as the measured switching tube has not failed; If the maximum value of the sampling result exceeds a preset value or is equal to zero, it is determined that the switching device, which is the measured switching device, fails.

7. The double-pulse test method for the three-phase conversion circuit according to claim 6, characterized in that, After obtaining the test results of each of the switching devices that are the measured switching devices respectively, it further includes: Judging whether each of the switching devices fails; If each of the switching devices does not fail, discharge each DC-side capacitor in the three-phase conversion circuit to zero voltage, and disconnect the short circuit between each AC port of the three-phase conversion circuit; If at least one of the switching devices fails, notify the tester to replace the failed switching device.

8. A three-phase converter, characterized in that, It includes: A three-phase conversion circuit and a controller; where: The controller is respectively connected to the control terminals of each switching device in the three-phase conversion circuit, and is used to execute the double-pulse test method of the three-phase conversion circuit according to any one of claims 1 to 7.

9. The three-phase converter according to claim 8, characterized in that It further includes: a switching device; where: Each connection port on one side of the switching device is respectively connected to each AC port of the three-phase conversion circuit, and each connection port on the other side of the switching device is connected; The switching device is controlled by the controller and is used to short-circuit each pair of the AC ports.

10. The three-phase converter according to claim 9, wherein, The switching device is a contactor, and one end of each normally open contact in the contactor is respectively connected to each AC port of the three-phase conversion circuit, and the other ends of each normally open contact in the contactor are connected to each other.

11. The three-phase converter according to any one of claims 8 to 10, characterized in that, The switching device in the three-phase conversion circuit is an insulated gate bipolar transistor IGBT, an integrated gate-commutated thyristor IGCT, or a gate-injected enhanced transistor IEGT.

12. A wind power converter, characterized in that, It includes: A controller, a machine-side converter, and a grid-side converter; where: The DC side of the machine-side converter is connected to the DC side of the grid-side converter; The main circuits of the machine-side converter and the grid-side converter are both three-phase conversion circuits; The controller is respectively connected to the control terminals of each switching device in each of the three-phase conversion circuits, and is used to successively execute the double-pulse test method of the three-phase conversion circuit according to any one of claims 1 to 7 on the machine-side converter and the grid-side converter.

13. The wind power converter according to claim 12, characterized in that, It further includes: Two switching devices; where: The switching device corresponds to the three-phase conversion circuit one by one; Each connection port on one side of the switching device is respectively connected to each AC port of the corresponding three-phase conversion circuit, and each connection port on the other side of the switching device is connected; The switching device is controlled by the controller and is used to short-circuit each pair of the AC ports.

14. The wind power converter according to claim 13, wherein The switching device is a contactor, and one end of each normally open contact in the contactor is respectively connected to each AC port of the corresponding three-phase conversion circuit, and the other ends of each normally open contact in the contactor are connected to each other.

15. The wind power converter according to claim 14, characterized in that, If both of the two switching devices are contactors, the normally closed contact in each contactor is arranged at: between the relay in the other contactor and the AC power supply.

16. The wind power converter according to any one of claims 12 to 15, characterized in that, The controller is further used for: When it is detected that each AC end of the two three-phase conversion circuits is short-circuited in pairs, stop executing the double-pulse test method of the three-phase conversion circuit.

17. The wind power converter according to claim 16, characterized in that, If the wind power converter includes two switching devices and both of the two switching devices are contactors, the controller is further used for: When it is detected that the normally open contacts of the two contactors are closed simultaneously, stop executing the dual-pulse test method of the three-phase conversion circuit.

18. The wind power converter according to any one of claims 12 to 15, characterized in that, The switching tubes in the three-phase conversion circuit are insulated gate bipolar transistors (IGBTs), integrated gate-commutated thyristors (IGCTs), or gate-injected enhanced transistors (IEGTs).

19. The wind power converter according to any one of claims 12 to 15, characterized in that, The controller is integrated into the main controller in the wind turbine unit connected to the wind power converter.

Images