Three-level converter soft-start circuit and control method and device thereof

Abstract

The application discloses a three-level converter soft-start circuit and a control method and device thereof. The circuit comprises a power distribution power supply, a split transformer and a plurality of rectifier bridges. The plurality of rectifier bridges comprise a first rectifier bridge, a second rectifier bridge, a third rectifier bridge and a fourth rectifier bridge. The alternating current end of the first rectifier bridge and the alternating current end of the third rectifier bridge are connected in parallel, and the alternating current end of the second rectifier bridge and the alternating current end of the fourth rectifier bridge are connected in parallel. The output end of the power distribution power supply is connected with the input end of the split transformer. The first output end of the split transformer, the alternating current end of the first rectifier bridge and the alternating current end of the third rectifier bridge are connected. The second output end of the split transformer, the alternating current end of the second rectifier bridge and the alternating current end of the fourth rectifier bridge are connected. Through the application, the problem that when the three-level converter soft-start system is rectified from the power grid to charge the DC bus, the grid-connected impact current is large is solved.

Description

Technical Field

[0001] This application relates to the field of control circuit technology, and more specifically, to a three-level converter soft-start circuit and its control method and apparatus. Background Technology

[0002] Type I-NPC three-level technology has advantages such as low switching losses, high efficiency, and low output harmonic content. This technology is currently widely used in power electronic products, such as various types of full-power or doubly-fed wind power converters. A schematic diagram of the circuit topology for applying this three-level technology to a full-power wind power converter is shown below. Figure 1 As shown. Furthermore, combining this type of three-level technology with an 1140VAC voltage level can further increase the overall power and reduce the overall cost. Moreover, the dual-bus model can be matched with dual-winding motors, so in the 1140VAC three-level wind power converter system, the use of dual buses can provide the circuit system with a certain degree of operational redundancy and high flexibility. However, as the AC terminal voltage increases, the demand for DC bus voltage will also increase. If the existing 690VAC system's non-isolated soft-start scheme is still used in the 1140VAC three-level wind power converter system—that is, charging the DC bus after rectifying the power drawn from the grid—the soft-start circuit devices in this system will need to be reselected due to the high voltage, and this will lead to a large inrush current problem during grid connection.

[0003] There is currently no effective solution to the problem of large grid-connected inrush current when charging the DC bus after rectifying power drawn from the grid in a three-level converter soft-start system. Summary of the Invention

[0004] The main objective of this application is to provide a soft-start circuit for a three-level converter and its control method and device, so as to solve the problem in the related art that when the power is drawn from the grid and rectified to charge the DC bus in the soft-start system of the three-level converter, it will lead to a large grid-connected inrush current.

[0005] To achieve the above objectives, according to one aspect of this application, a three-level converter soft-start circuit is provided, comprising: a power distribution power supply; a split transformer; and a plurality of rectifier bridges, wherein the plurality of rectifier bridges includes a first rectifier bridge, a second rectifier bridge, a third rectifier bridge, and a fourth rectifier bridge, wherein the AC terminals of the first rectifier bridge and the third rectifier bridge are connected in parallel, and the AC terminals of the second rectifier bridge and the fourth rectifier bridge are connected in parallel; wherein the output terminal of the power distribution power supply is connected to the input terminal of the split transformer, the first output terminal of the split transformer, the AC terminal of the first rectifier bridge, and the AC terminal of the third rectifier bridge are connected, and the second output terminal of the split transformer, the AC terminal of the second rectifier bridge, and the AC terminal of the fourth rectifier bridge are connected.

[0006] Furthermore, the circuit further includes: a plurality of resistors, wherein the plurality of resistors includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor; the DC positive terminal of the first rectifier bridge is connected to a first terminal of the first resistor; the DC negative terminal of the first rectifier bridge, the DC positive terminal of the second rectifier bridge, and the first terminal of the second resistor are connected; the DC negative terminal of the second rectifier bridge and the first terminal of the third resistor are connected; the DC positive terminal of the third rectifier bridge and the DC positive terminal of the fourth rectifier bridge are connected to a first terminal of the fifth resistor; and the DC negative terminal of the fourth rectifier bridge and the first terminal of the sixth resistor are connected.

[0007] Furthermore, the circuit further includes: a plurality of bus capacitors, wherein the plurality of bus capacitors includes a first positive bus capacitor, a first negative bus capacitor, a second positive bus capacitor, and a second negative bus capacitor; the second end of the first resistor is connected to the first end of the first positive bus capacitor, the second end of the second resistor, the second end of the first positive bus capacitor, and the first end of the first negative bus capacitor are connected, the second end of the third resistor is connected to the second end of the first negative bus capacitor, the second end of the fourth resistor is connected to the first end of the second positive bus capacitor, the second end of the fifth resistor, the second end of the second positive bus capacitor, and the first end of the second negative bus capacitor are connected, and the second end of the sixth resistor is connected to the second end of the second negative bus capacitor.

[0008] Furthermore, the circuit further includes: a first type of switch and a second type of switch disposed between the power distribution power supply and the split transformer, wherein the first type of switch includes a first switch, a second switch, and a third switch, and the second type of switch includes a fourth switch, a fifth switch, and a sixth switch; a first output terminal of the power distribution power supply is connected to a first terminal of the first switch, a second terminal of the first switch is connected to a first terminal of the fourth switch, a second terminal of the fourth switch is connected to a first input terminal of the split transformer, a second output terminal of the power distribution power supply is connected to a first terminal of the second switch, a second terminal of the second switch is connected to a first terminal of the fifth switch, a second terminal of the fifth switch is connected to a second input terminal of the split transformer, a third output terminal of the power distribution power supply is connected to a first terminal of the third switch, a second terminal of the third switch is connected to a first terminal of the sixth switch, and a second terminal of the sixth switch is connected to a third input terminal of the split transformer.

[0009] To achieve the above objectives, according to one aspect of this application, a control method for a three-level converter soft-start circuit is provided. The control method is used to control the three-level converter soft-start circuit described in any one of the above claims, comprising: obtaining AC power one through the power distribution power supply; converting AC power one into AC power two and AC power three through the split transformer, wherein the voltage values ​​of AC power two and AC power three are both greater than the voltage value of AC power one; rectifying AC power two and AC power three to obtain DC power one and DC power two; charging the DC bus where the bus capacitor is located according to DC power one and / or DC power two; and controlling the operating state of a second type of switch according to the charging voltage value of the DC bus, thereby realizing the control of the three-level converter soft-start circuit.

[0010] Further, the DC bus where the first positive bus capacitor is located is the first positive DC bus, the DC bus where the first negative bus capacitor is located is the first negative DC bus, the DC bus where the second positive bus capacitor is located is the second positive DC bus, and the DC bus where the second negative bus capacitor is located is the second negative DC bus. The first positive DC bus and the first negative DC bus form a first group of DC buses, and the second positive DC bus and the second negative DC bus form a second group of DC buses. If the DC bus is the first group of DC buses and the second group of DC buses, charging the DC bus where the bus capacitor is located according to DC current one and / or DC current two includes: obtaining DC current one and DC current two; charging the first positive DC bus and the first negative DC bus in the first group of DC buses according to DC current one; and charging the second positive DC bus and the second negative DC bus in the second group of DC buses according to DC current two.

[0011] Further, controlling the operating state of the second type of switch based on the charging voltage value of the DC bus to achieve control of the soft-start circuit of the three-level converter includes: obtaining the charging voltage value of the first group of DC buses based on the charging voltage difference between the first positive DC bus and the first negative DC bus; obtaining the charging voltage value of the second group of DC buses based on the charging voltage difference between the second positive DC bus and the second negative DC bus; determining whether the charging voltage value of any one group of DC buses in the first group of DC buses and the second group of DC buses is equal to a first preset voltage value; if ... If the charging voltage of the DC bus group is equal to the first preset voltage value, the DC power on the first and second DC buses is inverted to obtain AC power four. It is then determined whether the frequency and phase of AC power four and the target AC power are the same. If the frequency and phase of AC power four and the target AC power are the same, it is then determined whether the voltage difference between AC power four and the target AC power is equal to the second preset voltage value. If the voltage difference between AC power four and the target AC power is equal to the second preset voltage value, the operating state of the second type of switch is controlled to be open, thereby achieving disconnection control of the three-level converter soft-start circuit.

[0012] Further, controlling the operating state of the second type of switch according to the charging voltage value of the DC bus to achieve control of the soft-start circuit of the three-level converter includes: obtaining the charging voltage value of the first group of DC buses based on the charging voltage difference between the first positive DC bus and the first negative DC bus; determining whether the charging voltage value of the first group of DC buses is equal to a first preset voltage value; if the charging voltage value of the first group of DC buses is equal to the first preset voltage value, then inverting the DC power on the first group of DC buses to obtain AC power 5; determining whether the frequency and phase of AC power 5 and the target AC power are the same; if the frequency and phase of AC power 5 and the target AC power are the same, then determining whether the voltage difference between AC power 5 and the target AC power is equal to a second preset voltage value; if the voltage difference between AC power 5 and the target AC power is equal to the second preset voltage value, then controlling the operating state of the second type of switch to the open state to achieve disconnection control of the soft-start circuit of the three-level converter.

[0013] Further, if the DC bus is the first group of DC buses, controlling the operating state of the second type of switch according to the charging voltage value of the DC bus to achieve control of the three-level converter soft-start circuit includes: obtaining the charging voltage value of the first group of DC buses based on the charging voltage difference between the first positive DC bus and the first negative DC bus; determining whether the charging voltage value of the first group of DC buses is equal to a first preset voltage value; if the charging voltage value of the first group of DC buses is equal to the first preset voltage value, then inverting the DC power on the first group of DC buses to obtain AC power VI; determining whether the frequency and phase of AC power VI and the target AC power are the same; if the frequency and phase of AC power VI and the target AC power are the same, then determining whether the voltage difference between AC power VI and the target AC power is equal to a second preset voltage value; if the voltage difference between AC power VI and the target AC power is equal to the second preset voltage value, then controlling the operating state of the second type of switch to the open state to achieve disconnection control of the three-level converter soft-start circuit.

[0014] Furthermore, before obtaining AC power from the power distribution source, the method further includes: triggering closing commands for a first type of switch and a second type of switch; and responding to the closing commands for the first type of switch and the second type of switch by performing the step of obtaining AC power from the power distribution source.

[0015] To achieve the above objectives, according to another aspect of this application, a control device for a three-level converter soft-start circuit is provided. The control device is used to control the three-level converter soft-start circuit described in any one of the above claims, comprising: a first acquisition unit for acquiring AC power one through the power distribution power supply; a first conversion unit for converting AC power one into AC power two and AC power three through the split transformer, wherein the voltage values ​​of AC power two and AC power three are both greater than the voltage value of AC power one; a first rectification unit for rectifying AC power two and AC power three to obtain DC power one and DC power two; a first charging unit for charging the DC bus where the bus capacitor is located according to DC power one and / or DC power two; and a first control unit for controlling the operating state of a second type of switch according to the charging voltage value of the DC bus, thereby realizing the control of the three-level converter soft-start circuit.

[0016] Further, the DC bus containing the first positive bus capacitor is the first positive DC bus, the DC bus containing the first negative bus capacitor is the first negative DC bus, the DC bus containing the second positive bus capacitor is the second positive DC bus, and the DC bus containing the second negative bus capacitor is the second negative DC bus. The first positive DC bus and the first negative DC bus form a first group of DC buses, and the second positive DC bus and the second negative DC bus form a second group of DC buses. If the DC buses are the first group of DC buses and the second group of DC buses, the first charging unit includes: a first acquisition module for acquiring DC power supply one and DC power supply two; a first charging module for charging the first positive DC bus and the first negative DC bus in the first group of DC buses according to DC power supply one; and a second charging module for charging the second positive DC bus and the second negative DC bus in the second group of DC buses according to DC power supply two.

[0017] Further, the first control unit includes: a first processing module, configured to obtain the charging voltage value of the first group of DC buses based on the charging voltage difference between the first positive DC bus and the first negative DC bus; a second processing module, configured to obtain the charging voltage value of the second group of DC buses based on the charging voltage difference between the second positive DC bus and the second negative DC bus; a first judgment module, configured to judge whether the charging voltage value of any one group of DC buses in the first group of DC buses and the second group of DC buses is equal to a first preset voltage value; and a first inverter module, configured to, if the charging voltage value of any one group of DC buses in the first group of DC buses and the second group of DC buses is equal to the first preset voltage value, then... The first preset voltage value is used to invert the DC power on the first and second DC buses to obtain AC power four; the second judgment module is used to determine whether the frequency and phase of AC power four and the target AC power are the same; the third judgment module is used to determine whether the voltage difference between AC power four and the target AC power is equal to the second preset voltage value if the frequency and phase of AC power four and the target AC power are the same; the first control module is used to control the working state of the second type of switch to the open state if the voltage difference between AC power four and the target AC power is equal to the second preset voltage value, so as to realize the disconnection control of the soft start circuit of the three-level converter.

[0018] Further, the first control unit includes: a third processing module, used to obtain the charging voltage value of the first group of DC buses based on the charging voltage difference between the first positive DC bus and the first negative DC bus; a fourth judgment module, used to judge whether the charging voltage value of the first group of DC buses is equal to a first preset voltage value; a second inverter module, used to invert the DC power on the first group of DC buses to obtain AC power if the charging voltage value of the first group of DC buses is determined to be equal to the first preset voltage value; a fifth judgment module, used to judge whether the frequency and phase of the AC power and the target AC power are the same; a sixth judgment module, used to judge whether the voltage difference between the AC power and the target AC power is equal to a second preset voltage value if the frequency and phase of the AC power and the target AC power are determined to be the same; and a second control module, used to control the working state of the second type of switch to the open state if the voltage difference between the AC power and the target AC power is determined to be equal to the second preset voltage value, so as to realize the disconnection control of the soft start circuit of the three-level converter.

[0019] Further, if the DC bus is the first group of DC buses, the first control unit includes: a fourth processing module, used to obtain the charging voltage value of the first group of DC buses based on the charging voltage difference between the first positive DC bus and the first negative DC bus; a seventh judgment module, used to determine whether the charging voltage value of the first group of DC buses is equal to a first preset voltage value; a third inverter module, used to invert the DC power on the first group of DC buses to obtain AC power if the charging voltage value of the first group of DC buses is determined to be equal to the first preset voltage value; an eighth judgment module, used to determine whether the frequency and phase of the AC power and the target AC power are the same; a ninth judgment module, used to determine whether the voltage difference between the AC power and the target AC power is equal to a second preset voltage value if the frequency and phase of the AC power and the target AC power are determined to be the same; and a third control module, used to control the working state of the second type of switch to the open state if the voltage difference between the AC power and the target AC power is determined to be equal to the second preset voltage value, so as to realize the disconnection control of the soft start circuit of the three-level converter.

[0020] Furthermore, the device further includes: a first triggering unit, configured to trigger a closing command for a first type of switch and a second type of switch before obtaining AC power from the power distribution source; and a first response unit, configured to respond to the closing commands for the first type of switch and the second type of switch and execute the step of obtaining AC power from the power distribution source.

[0021] To achieve the above objectives, according to another aspect of this application, a processor is provided for running a program, wherein the program executes the control method for the three-level converter soft-start circuit described in any one of the above claims.

[0022] To achieve the above objectives, according to another aspect of this application, a computer-readable storage medium is provided, the storage medium including a stored program, wherein the program, when executed, performs the control method of the three-level converter soft-start circuit described in any one of the above claims.

[0023] The three-level converter soft-start circuit provided in this application has the following structure: a power distribution power supply; a split transformer; and multiple rectifier bridges, including a first rectifier bridge, a second rectifier bridge, a third rectifier bridge, and a fourth rectifier bridge. The AC terminals of the first and third rectifier bridges are connected in parallel, and the AC terminals of the second and fourth rectifier bridges are also connected in parallel. The output terminal of the power distribution power supply is connected to the input terminal of the split transformer. The first output terminal of the split transformer, the AC terminal of the first rectifier bridge, and the AC terminal of the third rectifier bridge are connected. The second output terminal of the split transformer, the AC terminal of the second rectifier bridge, and the AC terminal of the fourth rectifier bridge are also connected. This solves the problem in related technologies where, when power is drawn from the grid, rectified, and then charged to the DC bus in a three-level converter soft-start system, a large grid-connected inrush current occurs. The three-level converter soft-start circuit provided in this application enables the system to draw power from the distribution power supply and charge the DC bus after conversion and rectification when the three-level converter soft-start system is in a high-voltage state. This improves the DC charging capacity of the soft-start circuit, reduces the grid connection inrush current, and solves the problem of difficult selection of soft-start devices in 1140V wind power systems. Attached Figure Description

[0024] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0025] Figure 1 This is a schematic diagram of the circuit topology for applying Type I-NPC three-level technology to full-power wind power converter products based on existing technology;

[0026] Figure 2 This is a schematic diagram of a three-level converter soft-start circuit provided according to an embodiment of this application. Figure 1 ;

[0027] Figure 3 This is a schematic diagram of a three-level converter soft-start circuit provided according to an embodiment of this application. Figure 2 ;

[0028] Figure 4 This is a flowchart of a control method for a three-level converter soft-start circuit according to an embodiment of this application;

[0029] Figure 5 This is a schematic diagram of the control device for a three-level converter soft-start circuit provided according to an embodiment of this application. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] Figure 2 This is a schematic diagram of a three-level converter soft-start circuit according to an embodiment of this application. Figure 1 .like Figure 2 As shown in the diagram, the schematic includes the following: a power distribution source; a split transformer; and multiple rectifier bridges, including a first rectifier bridge, a second rectifier bridge, a third rectifier bridge, and a fourth rectifier bridge. The AC terminals of the first and third rectifier bridges are connected in parallel, as are the AC terminals of the second and fourth rectifier bridges. The output terminal of the power distribution source is connected to the input terminal of the split transformer. The first output terminal of the split transformer, the AC terminal of the first rectifier bridge, and the AC terminal of the third rectifier bridge are connected. The second output terminal of the split transformer, the AC terminal of the second rectifier bridge, and the AC terminal of the fourth rectifier bridge are also connected.

[0034] It should be noted that the aforementioned power distribution source can be... Figure 3 The 400VAC power distribution box in the middle, the aforementioned split transformer can be Figure 3 The 400VAC / 690VAC*2 soft-start dual-split transformer mentioned above can be a soft-start rectifier bridge, and the first, second, third, and fourth rectifier bridges mentioned above can be... Figure 3 VD1, VD2, VD3, and VD4.

[0035] The three-level converter soft-start circuit provided in this application enables the system to draw power from the distribution power supply and charge the DC bus after conversion and rectification when the three-level converter soft-start system is in a high-voltage state. This improves the DC charging capacity of the soft-start circuit, reduces the grid connection inrush current, and solves the problem of difficult selection of soft-start devices in 1140V wind power systems.

[0036] Optionally, in the three-level converter soft-start circuit provided in the embodiments of this application, the circuit further includes: a plurality of resistors, wherein the plurality of resistors includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor; the DC positive terminal of the first rectifier bridge is connected to the first terminal of the first resistor; the DC negative terminal of the first rectifier bridge, the DC positive terminal of the second rectifier bridge, and the first terminal of the second resistor are connected; the DC negative terminal of the second rectifier bridge is connected to the first terminal of the third resistor; the DC positive terminal of the third rectifier bridge and the DC positive terminal of the fourth rectifier bridge are connected to the first terminal of the fifth resistor; and the DC negative terminal of the fourth rectifier bridge is connected to the first terminal of the sixth resistor.

[0037] It should be noted that the aforementioned resistors can be soft-start resistors, and the first, second, third, fourth, fifth, and sixth resistors can be... Figure 3 R1, R2, R3, R4, R5, and R6.

[0038] By connecting the resistor to the rectifier bridge, the DC bus can be charged, ensuring that the DC bus has a stable charging voltage.

[0039] Optionally, in the three-level converter soft-start circuit provided in the embodiments of this application, the circuit further includes: a plurality of bus capacitors, wherein the plurality of bus capacitors includes a first positive bus capacitor, a first negative bus capacitor, a second positive bus capacitor, and a second negative bus capacitor; the second end of a first resistor is connected to the first end of the first positive bus capacitor, the second end of a second resistor, the second end of the first positive bus capacitor, and the first end of the first negative bus capacitor are connected, the second end of a third resistor is connected to the second end of the first negative bus capacitor, the second end of a fourth resistor is connected to the first end of the second positive bus capacitor, the second end of a fifth resistor, the second end of the second positive bus capacitor, and the first end of the second negative bus capacitor are connected, and the second end of a sixth resistor is connected to the second end of the second negative bus capacitor.

[0040] It should be noted that the aforementioned first positive bus capacitor, first negative bus capacitor, second positive bus capacitor, and second negative bus capacitor can be... Figure 3 C1, C2, C3, and C4 in the example.

[0041] By connecting capacitors and resistors, a voltage difference can be created between the positive and negative bus capacitors, making it easy to calculate the charging voltage between them. Furthermore, while theoretically no current flows through the second resistor R2 and the fifth resistor R5, in practice, when there is a half-bus voltage imbalance in the circuit system, these two resistors can act as current limiters, thus balancing the positive and negative bus capacitors.

[0042] Optionally, in the three-level converter soft-start circuit provided in the embodiments of this application, the circuit further includes: setting a first type of switch and a second type of switch between the power distribution power supply and the split transformer, wherein the first type of switch includes a first switch, a second switch and a third switch, and the second type of switch includes a fourth switch, a fifth switch and a sixth switch; the first output terminal of the power distribution power supply is connected to the first terminal of the first switch, the second terminal of the first switch is connected to the first terminal of the fourth switch, the second terminal of the fourth switch is connected to the first input terminal of the split transformer, the second output terminal of the power distribution power supply is connected to the first terminal of the second switch, the second terminal of the second switch is connected to the first terminal of the fifth switch, the second terminal of the fifth switch is connected to the second input terminal of the split transformer, the third output terminal of the power distribution power supply is connected to the first terminal of the third switch, the second terminal of the third switch is connected to the first terminal of the sixth switch, and the second terminal of the sixth switch is connected to the third input terminal of the split transformer.

[0043] It should be noted that the aforementioned first type of switch can be a soft start motor switch or a soft start fuse, and the aforementioned first, second, and third switches can be Figure 3 S1, S2, and S3; the second type of switch mentioned above can be a soft-start contactor, and the fourth, fifth, and sixth switches mentioned above can be... Figure 3 S4, S5, and S6 in the example.

[0044] The first type of switch can create a break point when the soft-start rectifier bridge or soft-start resistor fails and short-circuits, thereby cutting off the connection between the failed device and the power supply; the second type of switch can control the operating state of the soft-start circuit of the three-level converter.

[0045] By using switches, the safety and reliability of the circuit system can be ensured, and the operating state of the circuit system can be effectively controlled.

[0046] The three-level converter soft-start circuit provided in this application enables the system to draw power from the distribution power supply and charge the DC bus after conversion and rectification when the three-level converter soft-start system is in a high-voltage state. This improves the DC charging capacity of the soft-start circuit, reduces the grid connection inrush current, and solves the problem of difficult selection of soft-start devices in 1140V wind power systems.

[0047] Figure 4 This is a flowchart of a control method for a three-level converter soft-start circuit according to an embodiment of this application. This control method can be used to control any of the aforementioned three-level converter soft-start circuits, such as… Figure 4 As shown, the method includes the following steps:

[0048] Step S401: Obtain AC power through the power distribution power supply.

[0049] from Figure 3 Power is drawn from the 400VAC power distribution box to obtain 400V AC power.

[0050] In step S402, AC power 1 is converted into AC power 2 and AC power 3 by a split transformer, wherein the voltage values ​​of AC power 2 and AC power 3 are both greater than the voltage values ​​of AC power 1.

[0051] pass Figure 3 The 400VAC / 690VAC*2 soft-start dual-split transformer converts 400V AC power into two 690V AC power streams.

[0052] Since the voltage values ​​of 400V and 690V are not as high as the grid voltage of 1140V, even when the three-level converter soft start system is in a high-voltage 1140V state, all the components of the above soft start circuit can continue to use the low-voltage power distribution components of the 690VAC system without having to reselect them, thereby improving the versatility of the soft start circuit and reducing the cost of the circuit system.

[0053] Step S403: Rectify AC power supply 2 and AC power supply 3 to obtain DC power supply 1 and DC power supply 2.

[0054] The two sets of 690V AC power are rectified to obtain DC power one and DC power two.

[0055] Step S404: Charge the DC bus where the bus capacitor is located according to DC power supply one and / or DC power supply two.

[0056] The rectified DC power 1 and / or DC power 2 are used to charge the positive bus where the positive bus capacitor is located and the negative bus where the negative bus capacitor is located, respectively. Theoretically, the voltage of each group of DC buses can be charged to a maximum of 1951V.

[0057] Step S405: Control the operating state of the second type of switch according to the charging voltage value of the DC bus, so as to realize the control of the soft start circuit of the three-level converter.

[0058] Based on the charging voltage value of each DC bus, the soft start contactor is controlled to open or close, i.e., the soft start contactor is controlled. Figure 3 The opening or closing of S4 to S6 in the circuit enables control of the soft-start circuit of the three-level converter.

[0059] Through the above steps, the working state of the switch can be controlled to realize the control of the soft start circuit of the three-level converter. That is, when the three-level converter soft start system is in a high-voltage state, it can draw power from the power distribution power supply and charge the DC bus after conversion and rectification. This improves the charging capacity of DC power in the soft start circuit and reduces the grid connection inrush current. This solves the problem in related technologies where the grid connection inrush current is large when drawing power from the grid and charging the DC bus after rectification in the three-level converter soft start system.

[0060] Optionally, in the control method of the three-level converter soft-start circuit provided in the embodiments of this application, the DC bus where the first positive bus capacitor is located is the first positive DC bus, the DC bus where the first negative bus capacitor is located is the first negative DC bus, the DC bus where the second positive bus capacitor is located is the second positive DC bus, and the DC bus where the second negative bus capacitor is located is the second negative DC bus. The first positive DC bus and the first negative DC bus form a first group of DC buses, and the second positive DC bus and the second negative DC bus form a second group of DC buses. If the DC bus is the first group of DC buses and the second group of DC buses, charging the DC bus where the bus capacitor is located according to DC current one and / or DC current two includes: obtaining DC current one and DC current two; charging the first positive DC bus and the first negative DC bus in the first group of DC buses according to DC current one; and charging the second positive DC bus and the second negative DC bus in the second group of DC buses according to DC current two.

[0061] The aforementioned three-level converter can be used for an 1140VAC three-level wind power converter system. When both busbars operate simultaneously, the positive and negative busbars of the two DC busbars are charged according to the rectified DC power supply one and DC power supply two, respectively.

[0062] The above scheme can ensure that each busbar has a charging voltage.

[0063] Optionally, in the control method for the soft-start circuit of a three-level converter provided in this application embodiment, controlling the operating state of the second type of switch according to the charging voltage value of the DC bus to realize the control of the soft-start circuit of the three-level converter includes: obtaining the charging voltage value of the first group of DC buses according to the charging voltage difference between the first positive DC bus and the first negative DC bus; obtaining the charging voltage value of the second group of DC buses according to the charging voltage difference between the second positive DC bus and the second negative DC bus; determining whether the charging voltage value of any one group of DC buses in the first group of DC buses and the second group of DC buses is equal to a first preset voltage value; if the first group of DC buses is determined to be equal to a first preset voltage value, the control method for the soft-start circuit of the three-level converter includes: obtaining the charging voltage value of the first group of DC buses according to the charging voltage difference between the first positive DC bus and the first negative DC bus; obtaining the charging voltage value of the second group of DC buses according to the charging voltage difference between the second positive DC bus and the second negative DC bus; determining whether the charging voltage value of any one group of DC buses in the first group of DC buses is equal to a first preset voltage value; if the charging voltage value of any one group of DC buses in the first group of DC buses is equal to a first preset voltage value, the control method for the soft-start circuit of the three-level converter includes: obtaining the charging voltage value of the first group of DC buses according to the charging voltage difference between the first ... determining whether the charging voltage value of any one group of DC buses If the charging voltage of any one of the two DC bus groups is equal to the first preset voltage value, the DC power on the first and second DC bus groups is inverted to obtain AC power four. It is then determined whether the frequency and phase of AC power four and the target AC power are the same. If it is determined that the frequency and phase of AC power four and the target AC power are the same, it is then determined whether the voltage difference between AC power four and the target AC power is equal to the second preset voltage value. If it is determined that the voltage difference between AC power four and the target AC power is equal to the second preset voltage value, the operating state of the second type of switch is controlled to be in the open state to realize the disconnection control of the soft start circuit of the three-level converter.

[0064] When both sets of buses operate simultaneously, the charging voltage of the first DC bus can be calculated based on the voltage difference between the first positive DC bus and the first negative DC bus; similarly, the charging voltage of the second DC bus can be calculated based on the voltage difference between the second positive DC bus and the second negative DC bus. The system then checks whether the charging voltage of either the first or second DC bus equals a first preset voltage value. If either DC bus voltage reaches the first preset voltage value, the converter grid-side power modules on both buses simultaneously begin inverter power generation, inverting the DC power on both DC buses to AC power, and simultaneously initiating AC filter capacitor voltage synchronization closed-loop control and AC... Current synchronous closed-loop control: If the voltage of either DC bus fails to reach the first preset voltage value, the grid-side power modules of the converters on both buses cannot simultaneously invert and generate voltage, nor can they invert DC power to AC power. Then, it checks whether the frequency and phase of the obtained AC filter capacitor voltage are the same as the grid voltage. If they are the same, it checks whether the voltage difference between the AC filter capacitor voltage and the grid voltage is equal to the second preset voltage value. If they are not the same, it does not check the voltage difference between the AC filter capacitor voltage and the grid voltage. If the voltage difference reaches the second preset voltage value, the grid-connected switch is closed, the AC filter capacitor voltage control is turned off, the DC bus voltage stabilization control is started, and the soft-start contactor is simultaneously disconnected, i.e., the circuit is cut off. Figure 3 S4 to S6 indicate the end of the soft start process; if the differential voltage does not reach the second preset voltage value, the grid-connected switch will not be closed, nor will the soft start contactor be disconnected.

[0065] By using two sets of DC buses, the circuit system can have a certain degree of operational redundancy and high flexibility.

[0066] Optionally, in the control method of the three-level converter soft-start circuit provided in this application embodiment, controlling the working state of the second type of switch according to the charging voltage value of the DC bus to realize the control of the three-level converter soft-start circuit includes: obtaining the charging voltage value of the first group of DC buses according to the charging voltage difference between the first positive DC bus and the first negative DC bus; determining whether the charging voltage value of the first group of DC buses is equal to a first preset voltage value; if it is determined that the charging voltage value of the first group of DC buses is equal to the first preset voltage value, then inverting the DC power on the first group of DC buses to obtain AC power 5; determining whether the frequency and phase of AC power 5 and the target AC power are the same; if it is determined that the frequency and phase of AC power 5 and the target AC power are the same, then determining whether the voltage difference between AC power 5 and the target AC power is equal to a second preset voltage value; if it is determined that the voltage difference between AC power 5 and the target AC power is equal to the second preset voltage value, then controlling the working state of the second type of switch to the open state to realize the disconnection control of the three-level converter soft-start circuit.

[0067] When both bus groups operate simultaneously, the first bus group soft-starts and the grid-side power modules under it invert and generate AC current, synchronizing the AC filter capacitor voltage with the grid voltage. The second bus group only soft-starts, but the power modules under it do not invert and generate AC current. Specifically, the charging voltage of the first DC bus group is calculated based on the voltage difference between the first positive and first negative DC buses. The charging voltage of the first DC bus group is then checked against a preset voltage value. If the voltage of the first DC bus group reaches the preset voltage value, the grid-side power modules under it begin inverting and generating AC current, converting the DC power on the first DC bus group to AC power, and simultaneously initiating AC filter capacitor voltage synchronization closed-loop control and AC current synchronization closed-loop control. If the voltage of the first DC bus group does not reach the preset voltage value, the first bus group... The converter grid-side power module cannot invert and generate waves, nor can it invert DC power to AC power. Then, it checks whether the frequency and phase of the obtained AC filter capacitor voltage are the same as the grid voltage. If they are the same, it checks whether the voltage difference between the AC filter capacitor voltage and the grid voltage equals a second preset voltage value. If they are different, it does not check the voltage difference between the AC filter capacitor voltage and the grid voltage. If the voltage difference reaches the second preset voltage value, it closes the grid-connected switch, shuts off the AC filter capacitor voltage control, starts the DC bus voltage stabilization control, and simultaneously disconnects the soft-start contactor, i.e., cuts off... Figure 3 S4 to S6 indicate the end of the soft start process; if the differential voltage does not reach the second preset voltage value, the grid-connected switch will not be closed, nor will the soft start contactor be disconnected.

[0068] The above solution provides a simple and convenient way to control the circuit system.

[0069] Optionally, in the control method of the three-level converter soft-start circuit provided in the embodiments of this application, if the DC bus is a first group of DC buses, controlling the working state of the second type of switch according to the charging voltage value of the DC bus to realize the control of the three-level converter soft-start circuit includes: obtaining the charging voltage value of the first group of DC buses according to the charging voltage difference between the first positive DC bus and the first negative DC bus; determining whether the charging voltage value of the first group of DC buses is equal to a first preset voltage value; if it is determined that the charging voltage value of the first group of DC buses is equal to the first preset voltage value, then inverting the DC power on the first group of DC buses to obtain AC power; determining whether the frequency and phase of AC power and the target AC power are the same; if it is determined that the frequency and phase of AC power and the target AC power are the same, then determining whether the voltage difference between AC power and the target AC power is equal to a second preset voltage value; if it is determined that the voltage difference between AC power and the target AC power is equal to the second preset voltage value, then controlling the working state of the second type of switch to the open state to realize the disconnection control of the three-level converter soft-start circuit.

[0070] A soft start can be successfully achieved even when any one group of buses is running independently. For example, when the first group of buses is running independently, the charging voltage value of the first group of DC buses is calculated based on the charging voltage difference between the first positive DC bus and the first negative DC bus; it is then checked whether the charging voltage value of the first group of DC buses is equal to a first preset voltage value; if the voltage of the first group of DC buses reaches the first preset voltage value, the power module on the grid side of the converter under the first group of buses starts inverter power generation and inverts the DC power on the first group of DC buses to obtain AC power, and simultaneously starts AC filter capacitor voltage synchronization closed-loop control and AC current synchronization closed-loop control; if the voltage of the first group of DC buses does not reach the first preset voltage value, ... If the converter grid-side power module on the first bus cannot invert and generate waves, nor can it invert DC power to AC power, then the frequency and phase of the obtained AC power filter capacitor voltage are checked to see if they are the same as the grid voltage. If they are the same, the voltage difference between the AC power filter capacitor voltage and the grid voltage is checked to see if it is equal to the second preset voltage value. If they are not the same, the voltage difference between the AC power filter capacitor voltage and the grid voltage is not checked. If the voltage difference reaches the second preset voltage value, the grid-connected switch is closed, the AC filter capacitor voltage control is turned off, the DC bus voltage stabilization control is started, and the soft start contactor is disconnected, i.e., the grid connection is cut off. Figure 3 S4 to S6 indicate the end of the soft start process; if the differential voltage does not reach the second preset voltage value, the grid-connected switch will not be closed, nor will the soft start contactor be disconnected.

[0071] The above solution facilitates redundant system operation.

[0072] Optionally, in the control method of the three-level converter soft-start circuit provided in the embodiments of this application, before obtaining AC power from the power distribution power supply, the method further includes: triggering the closing instructions of the first type of switch and the second type of switch; and responding to the closing instructions of the first type of switch and the second type of switch to perform the step of obtaining AC power from the power distribution power supply.

[0073] From Figure 3 Before obtaining 400V AC power from the 400VAC power distribution box, first close the soft start motor switch, that is, close... Figure 3 S1 to S3 are connected, and then after the converter issues a soft start command, the soft start contactor is closed, that is, closed. Figure 3 S4 to S6 in the text.

[0074] The above method can achieve control over the acquisition of alternating current, thereby ensuring the safety of the circuit system.

[0075] The control method for the three-level converter soft-start circuit provided in this application embodiment obtains AC power 1 from the power distribution power supply; converts AC power 1 into AC power 2 and AC power 3 through a split transformer, wherein the voltage values ​​of AC power 2 and AC power 3 are both greater than the voltage value of AC power 1; rectifies AC power 2 and AC power 3 to obtain DC power 1 and DC power 2; charges the DC bus where the bus capacitor is located according to DC power 1 and / or DC power 2; controls the working state of the second type of switch according to the charging voltage value of the DC bus, so as to realize the control of the three-level converter soft-start circuit. This solves the problem in related technologies where, when charging the DC bus after rectification of power drawn from the grid in a three-level converter soft-start system, a large grid-connected inrush current will occur. It can realize the function of drawing power from the power distribution power supply and charging the DC bus after conversion and rectification when the three-level converter soft-start system is in a high-voltage state, thereby improving the charging capacity of DC power in the soft-start circuit and reducing the grid-connected inrush current.

[0076] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0077] This application also provides a control device for a three-level converter soft-start circuit. It should be noted that the control device for the three-level converter soft-start circuit in this application can be used to execute the control method for the three-level converter soft-start circuit provided in this application. The control device for the three-level converter soft-start circuit provided in this application is described below.

[0078] Figure 5This is a schematic diagram of the control device for a three-level converter soft-start circuit according to an embodiment of this application. Figure 5 As shown, the device includes: a first acquisition unit 501, a first conversion unit 502, a first rectification unit 503, a first charging unit 504, and a first control unit 505.

[0079] Specifically, the first acquisition unit 501 is used to acquire AC power through the power distribution power supply;

[0080] The first conversion unit 502 is used to convert AC power 1 into AC power 2 and AC power 3 through a split transformer, wherein the voltage values ​​of AC power 2 and AC power 3 are both greater than the voltage value of AC power 1.

[0081] The first rectifier unit 503 is used to rectify AC power 2 and AC power 3 to obtain DC power 1 and DC power 2;

[0082] The first charging unit 504 is used to charge the DC bus where the DC bus capacitor is located according to DC power one and / or DC power two.

[0083] The first control unit 505 is used to control the working state of the second type of switch according to the charging voltage value of the DC bus, so as to realize the control of the soft start circuit of the three-level converter.

[0084] The control device for the three-level converter soft-start circuit provided in this application embodiment acquires AC power 1 through a power distribution power supply via a first acquisition unit 501; a first conversion unit 502 converts AC power 1 into AC power 2 and AC power 3 through a split transformer, wherein the voltage values ​​of AC power 2 and AC power 3 are both greater than the voltage value of AC power 1; a first rectification unit 503 rectifies AC power 2 and AC power 3 to obtain DC power 1 and DC power 2; a first charging unit 504 charges the DC bus where the bus capacitor is located according to DC power 1 and / or DC power 2; the first... The control unit 505 controls the operating state of the second type of switch according to the charging voltage value of the DC bus, so as to realize the control of the soft start circuit of the three-level converter. This solves the problem in related technologies that when the DC bus is charged after the power is taken from the grid and rectified, the grid-connected inrush current is large. It can realize the function of taking power from the distribution power supply and charging the DC bus after conversion and rectification when the three-level converter soft start system is in a high voltage state, thereby improving the charging capacity of DC power in the soft start circuit and reducing the grid-connected inrush current.

[0085] Optionally, in the control device of the three-level converter soft-start circuit provided in the embodiments of this application, the DC bus where the first positive bus capacitor is located is the first positive DC bus, the DC bus where the first negative bus capacitor is located is the first negative DC bus, the DC bus where the second positive bus capacitor is located is the second positive DC bus, and the DC bus where the second negative bus capacitor is located is the second negative DC bus. The first positive DC bus and the first negative DC bus form a first group of DC buses, and the second positive DC bus and the second negative DC bus form a second group of DC buses. If the DC buses are the first group of DC buses and the second group of DC buses, the first charging unit includes: a first acquisition module for acquiring DC current one and DC current two; a first charging module for charging the first positive DC bus and the first negative DC bus in the first group of DC buses according to DC current one; and a second charging module for charging the second positive DC bus and the second negative DC bus in the second group of DC buses according to DC current two.

[0086] Optionally, in the control device of the three-level converter soft-start circuit provided in this application embodiment, the first control unit includes: a first processing module, used to obtain the charging voltage value of the first group of DC buses based on the charging voltage difference between the first positive DC bus and the first negative DC bus; a second processing module, used to obtain the charging voltage value of the second group of DC buses based on the charging voltage difference between the second positive DC bus and the second negative DC bus; a first judgment module, used to judge whether the charging voltage value of any one of the first group of DC buses and the second group of DC buses is equal to a first preset voltage value; and a first inverter module, used to determine whether the charging voltage value of any one of the first group of DC buses and the second group of DC buses is equal to a first preset voltage value. If the charging voltage of the DC bus is equal to the first preset voltage value, the DC power on the first and second DC buses is inverted to obtain AC power four; the second judgment module is used to determine whether the frequency and phase of AC power four and the target AC power are the same; the third judgment module is used to determine whether the voltage difference between AC power four and the target AC power is equal to the second preset voltage value if the frequency and phase of AC power four and the target AC power are the same; the first control module is used to control the working state of the second type of switch to the open state if the voltage difference between AC power four and the target AC power is equal to the second preset voltage value, so as to realize the disconnection control of the soft start circuit of the three-level converter.

[0087] Optionally, in the control device for the three-level converter soft-start circuit provided in this application embodiment, the first control unit includes: a third processing module, used to obtain the charging voltage value of the first group of DC buses based on the charging voltage difference between the first positive DC bus and the first negative DC bus; a fourth judgment module, used to determine whether the charging voltage value of the first group of DC buses is equal to a first preset voltage value; a second inverter module, used to invert the DC power on the first group of DC buses to obtain AC power if the charging voltage value of the first group of DC buses is determined to be equal to the first preset voltage value; a fifth judgment module, used to determine whether the frequency and phase of AC power and the target AC power are the same; a sixth judgment module, used to determine whether the voltage difference between AC power and the target AC power is equal to a second preset voltage value if the frequency and phase of AC power and the target AC power are determined to be the same; and a second control module, used to control the working state of the second type of switch to the open state if the voltage difference between AC power and the target AC power is determined to be equal to the second preset voltage value, so as to realize the disconnection control of the three-level converter soft-start circuit.

[0088] Optionally, in the control device for the three-level converter soft-start circuit provided in this application embodiment, if the DC bus is a first group of DC buses, the first control unit includes: a fourth processing module, used to obtain the charging voltage value of the first group of DC buses based on the charging voltage difference between the first positive DC bus and the first negative DC bus; a seventh judgment module, used to determine whether the charging voltage value of the first group of DC buses is equal to a first preset voltage value; a third inverter module, used to invert the DC power on the first group of DC buses to obtain AC power if the charging voltage value of the first group of DC buses is determined to be equal to the first preset voltage value; an eighth judgment module, used to determine whether the frequency and phase of AC power and the target AC power are the same; a ninth judgment module, used to determine whether the voltage difference between AC power and the target AC power is equal to a second preset voltage value if the frequency and phase of AC power and the target AC power are determined to be the same; and a third control module, used to control the working state of the second type of switch to the open state if the voltage difference between AC power and the target AC power is determined to be equal to the second preset voltage value, so as to realize the disconnection control of the three-level converter soft-start circuit.

[0089] Optionally, in the control device of the three-level converter soft-start circuit provided in the embodiments of this application, the device further includes: a first triggering unit, used to trigger a first type of switch and a second type of switch closing command before obtaining AC power from the power distribution power supply; and a first response unit, used to respond to the first type of switch and the second type of switch closing command and perform the step of obtaining AC power from the power distribution power supply.

[0090] The control device of the three-level converter soft-start circuit includes a processor and a memory. The first acquisition unit 501, the first conversion unit 502, the first rectification unit 503, the first charging unit 504, and the first control unit 505 are all stored in the memory as program units. The processor executes the program units stored in the memory to realize the corresponding functions.

[0091] The processor contains a core, which retrieves the corresponding program unit from memory. One or more cores can be configured, and adjusting core parameters can reduce the inrush current during grid connection.

[0092] The memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0093] This invention provides a storage medium storing a program that, when executed by a processor, implements a control method for the soft-start circuit of a three-level converter.

[0094] This invention provides a processor for running a program, wherein the program executes a control method for the soft-start circuit of the three-level converter.

[0095] This invention provides a device including a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it performs the following steps: obtaining AC power 1 from the power distribution power supply; converting AC power 1 into AC power 2 and AC power 3 through the split transformer, wherein the voltage values ​​of AC power 2 and AC power 3 are both greater than the voltage value of AC power 1; rectifying AC power 2 and AC power 3 to obtain DC power 1 and DC power 2; charging the DC bus where the bus capacitor is located according to DC power 1 and / or DC power 2; and controlling the operating state of a second type of switch according to the charging voltage value of the DC bus to achieve control of the soft-start circuit of the three-level converter.

[0096] When the processor executes the program, it also implements the following steps: the DC bus where the first positive bus capacitor is located is the first positive DC bus, the DC bus where the first negative bus capacitor is located is the first negative DC bus, the DC bus where the second positive bus capacitor is located is the second positive DC bus, and the DC bus where the second negative bus capacitor is located is the second negative DC bus. The first positive DC bus and the first negative DC bus form a first group of DC buses, and the second positive DC bus and the second negative DC bus form a second group of DC buses. If the DC bus is the first group of DC buses and the second group of DC buses, charging the DC bus where the bus capacitor is located according to DC current one and / or DC current two includes: obtaining DC current one and DC current two; charging the first positive DC bus and the first negative DC bus in the first group of DC buses according to DC current one; and charging the second positive DC bus and the second negative DC bus in the second group of DC buses according to DC current two.

[0097] When the processor executes the program, it also performs the following steps: controlling the operating state of the second type of switch according to the charging voltage value of the DC bus, so as to realize the control of the soft start circuit of the three-level converter, including: obtaining the charging voltage value of the first group of DC buses according to the charging voltage difference between the first positive DC bus and the first negative DC bus; obtaining the charging voltage value of the second group of DC buses according to the charging voltage difference between the second positive DC bus and the second negative DC bus; determining whether the charging voltage value of any group of DC buses in the first group of DC buses and the second group of DC buses is equal to a first preset voltage value; if the charging voltage value of the first group of DC buses and the second group of DC buses is equal to a first preset voltage value; if the charging voltage value of the first group of DC buses and the second group of DC buses is equal to a first preset voltage value, the processor performs the following steps: controlling the operating state of the second type of switch according to the charging voltage value of the DC bus, so as to realize the control of the soft start circuit of the three-level converter, including: obtaining the charging voltage value of the first group of DC buses according to the charging voltage difference between the first positive DC bus and the second negative DC bus; determining whether the charging voltage value of any group of DC buses in ... determining whether the charging voltage value of any group of DC buses in the first group of DC buses and the second group of DC buses is equal to a first preset voltage value; determining whether the charging voltage value of any group of DC If the charging voltage of any set of DC buses in the busbar is equal to the first preset voltage value, then the DC power on the first set of DC buses and the second set of DC buses is inverted to obtain AC power four; it is determined whether the frequency and phase of AC power four and the target AC power are the same; if it is determined that the frequency and phase of AC power four and the target AC power are the same, then it is determined whether the voltage difference between AC power four and the target AC power is equal to the second preset voltage value; if it is determined that the voltage difference between AC power four and the target AC power is equal to the second preset voltage value, then the working state of the second type of switch is controlled to be in the open state, so as to realize the disconnection control of the soft start circuit of the three-level converter.

[0098] When the processor executes the program, it also performs the following steps: controlling the operating state of the second type of switch according to the charging voltage value of the DC bus to achieve control of the soft-start circuit of the three-level converter, including: obtaining the charging voltage value of the first group of DC buses according to the charging voltage difference between the first positive DC bus and the first negative DC bus; determining whether the charging voltage value of the first group of DC buses is equal to a first preset voltage value; if it is determined that the charging voltage value of the first group of DC buses is equal to the first preset voltage value, then inverting the DC power on the first group of DC buses to obtain AC power 5; determining whether the frequency and phase of AC power 5 and the target AC power are the same; if it is determined that the frequency and phase of AC power 5 and the target AC power are the same, then determining whether the voltage difference between AC power 5 and the target AC power is equal to a second preset voltage value; if it is determined that the voltage difference between AC power 5 and the target AC power is equal to the second preset voltage value, then controlling the operating state of the second type of switch to the open state to achieve disconnection control of the soft-start circuit of the three-level converter.

[0099] When the processor executes the program, it also performs the following steps: If the DC bus is the first group of DC buses, the operating state of the second type of switch is controlled according to the charging voltage value of the DC bus to achieve control of the soft-start circuit of the three-level converter, including: obtaining the charging voltage value of the first group of DC buses according to the charging voltage difference between the first positive DC bus and the first negative DC bus; determining whether the charging voltage value of the first group of DC buses is equal to a first preset voltage value; if it is determined that the charging voltage value of the first group of DC buses is equal to the first preset voltage value, then the DC power on the first group of DC buses is inverted to obtain AC power VI; determining whether the frequency and phase of AC power VI and the target AC power are the same; if it is determined that the frequency and phase of AC power VI and the target AC power are the same, then determining whether the voltage difference between AC power VI and the target AC power is equal to a second preset voltage value; if it is determined that the voltage difference between AC power VI and the target AC power is equal to the second preset voltage value, then the operating state of the second type of switch is controlled to be in the open state to achieve disconnection control of the soft-start circuit of the three-level converter.

[0100] When the processor executes the program, it also performs the following steps: before obtaining AC power from the power distribution source, the method further includes: triggering closing instructions for a first type of switch and a second type of switch; and responding to the closing instructions for the first type of switch and the second type of switch, performing the step of obtaining AC power from the power distribution source. The device in this document can be a server, PC, PAD, mobile phone, etc.

[0101] This application also provides a computer program product, which, when executed on a data processing device, is suitable for executing an initialization program with the following steps: obtaining AC power one through the power distribution power supply; converting AC power one into AC power two and AC power three through the split transformer, wherein the voltage values ​​of AC power two and AC power three are both greater than the voltage value of AC power one; rectifying AC power two and AC power three to obtain DC power one and DC power two; charging the DC bus where the bus capacitor is located according to DC power one and / or DC power two; controlling the operating state of a second type of switch according to the charging voltage value of the DC bus to realize the control of the soft start circuit of the three-level converter.

[0102] When executed on a data processing device, it is also suitable to execute an initialization program with the following steps: the DC bus where the first positive bus capacitor is located is the first positive DC bus, the DC bus where the first negative bus capacitor is located is the first negative DC bus, the DC bus where the second positive bus capacitor is located is the second positive DC bus, and the DC bus where the second negative bus capacitor is located is the second negative DC bus, wherein the first positive DC bus and the first negative DC bus form a first group of DC buses, and the second positive DC bus and the second negative DC bus form a second group of DC buses. If the DC bus is the first group of DC buses and the second group of DC buses, charging the DC bus where the bus capacitor is located according to DC current one and / or DC current two includes: obtaining DC current one and DC current two; charging the first positive DC bus and the first negative DC bus in the first group of DC buses according to DC current one; and charging the second positive DC bus and the second negative DC bus in the second group of DC buses according to DC current two.

[0103] When executed on a data processing device, it is also suitable to execute an initialization program with the following steps: controlling the operating state of the second type of switch according to the charging voltage value of the DC bus to realize the control of the soft-start circuit of the three-level converter, including: obtaining the charging voltage value of the first group of DC buses according to the charging voltage difference between the first positive DC bus and the first negative DC bus; obtaining the charging voltage value of the second group of DC buses according to the charging voltage difference between the second positive DC bus and the second negative DC bus; determining whether the charging voltage value of any group of DC buses in the first group of DC buses and the second group of DC buses is equal to a first preset voltage value; if the first group of DC buses is determined to be equal to the charging voltage value of the second group of DC buses, the charging voltage value of the second group of DC buses is equal to the charging voltage value of the third group of DC buses. If the charging voltage of any one of the second set of DC buses is equal to the first preset voltage value, then the DC power on the first set of DC buses and the second set of DC buses is inverted to obtain AC power four; it is determined whether the frequency and phase of AC power four and the target AC power are the same; if it is determined that the frequency and phase of AC power four and the target AC power are the same, then it is determined whether the voltage difference between AC power four and the target AC power is equal to the second preset voltage value; if it is determined that the voltage difference between AC power four and the target AC power is equal to the second preset voltage value, then the working state of the second type of switch is controlled to be in the open state, so as to realize the disconnection control of the soft start circuit of the three-level converter.

[0104] When executed on a data processing device, it is also suitable to execute an initialization program with the following steps: controlling the operating state of the second type of switch according to the charging voltage value of the DC bus to achieve control of the soft-start circuit of the three-level converter, including: obtaining the charging voltage value of the first group of DC buses according to the charging voltage difference between the first positive DC bus and the first negative DC bus; determining whether the charging voltage value of the first group of DC buses is equal to a first preset voltage value; if it is determined that the charging voltage value of the first group of DC buses is equal to the first preset voltage value, then inverting the DC power on the first group of DC buses to obtain AC power; determining whether the frequency and phase of the AC power and the target AC power are the same; if it is determined that the frequency and phase of the AC power and the target AC power are the same, then determining whether the voltage difference between the AC power and the target AC power is equal to a second preset voltage value; if it is determined that the voltage difference between the AC power and the target AC power is equal to the second preset voltage value, then controlling the operating state of the second type of switch to the open state to achieve disconnection control of the soft-start circuit of the three-level converter.

[0105] When executed on a data processing device, it is also suitable to execute an initialization program with the following steps: If the DC bus is the first group of DC buses, control the operating state of the second type of switch according to the charging voltage value of the DC bus to realize the control of the soft start circuit of the three-level converter, including: obtaining the charging voltage value of the first group of DC buses according to the charging voltage difference between the first positive DC bus and the first negative DC bus; determining whether the charging voltage value of the first group of DC buses is equal to a first preset voltage value; if it is determined that the charging voltage value of the first group of DC buses is equal to the first preset voltage value, then inverting the DC power on the first group of DC buses to obtain AC power VI; determining whether the frequency and phase of AC power VI and the target AC power are the same; if it is determined that the frequency and phase of AC power VI and the target AC power are the same, then determining whether the voltage difference between AC power VI and the target AC power is equal to a second preset voltage value; if it is determined that the voltage difference between AC power VI and the target AC power is equal to the second preset voltage value, then controlling the operating state of the second type of switch to the open state to realize the disconnection control of the soft start circuit of the three-level converter.

[0106] When executed on a data processing device, it is also suitable to execute an initialization program having the following method steps: before obtaining AC power from the power distribution source, the method further includes: triggering closing instructions for a first type of switch and a second type of switch; and in response to the closing instructions for the first type of switch and the second type of switch, performing the step of obtaining AC power from the power distribution source.

[0107] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0108] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1A device that provides the functions specified in one or more boxes.

[0109] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0110] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0111] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0112] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, like read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0113] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0114] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0115] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0116] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A soft-start circuit for a three-level converter, characterized in that, include: Power distribution; Split transformer; Multiple rectifier bridges, including a first rectifier bridge, a second rectifier bridge, a third rectifier bridge and a fourth rectifier bridge, wherein the AC terminals of the first rectifier bridge and the third rectifier bridge are connected in parallel, and the AC terminals of the second rectifier bridge and the fourth rectifier bridge are connected in parallel. The output terminal of the power distribution power supply is connected to the input terminal of the split transformer; the first output terminal of the split transformer, the AC terminal of the first rectifier bridge, and the AC terminal of the third rectifier bridge are connected; and the second output terminal of the split transformer, the AC terminal of the second rectifier bridge, and the AC terminal of the fourth rectifier bridge are connected. The soft-start circuit of the three-level converter is controlled by the following steps: AC power is obtained through the power distribution source; The split transformer converts AC power 1 into AC power 2 and AC power 3, wherein the voltage values ​​of AC power 2 and AC power 3 are both greater than the voltage value of AC power 1. The AC power supply 2 and the AC power supply 3 are rectified to obtain DC power supply 1 and DC power supply 2. Charge the DC bus where the bus capacitor is located according to DC power supply one and / or DC power supply two; The operating state of the second type of switch is controlled according to the charging voltage value of the DC bus to realize the control of the soft start circuit of the three-level converter. The second type of switch is a soft start contactor, which is set between the power distribution power supply and the split transformer. The control of the soft-start circuit of the three-level converter by adjusting the operating state of the second type of switch according to the charging voltage value of the DC bus includes: The charging voltage values ​​of the first group of DC buses are obtained based on the charging voltage difference between the first positive DC bus and the first negative DC bus. The charging voltage values ​​of the second set of DC buses are obtained based on the charging voltage difference between the second positive DC bus and the second negative DC bus. Determine whether the charging voltage value of any one of the first group of DC buses and the second group of DC buses is equal to the first preset voltage value; If it is determined that the charging voltage value of any one of the first group of DC buses and the second group of DC buses is equal to the first preset voltage value, then the DC power on the first group of DC buses and the second group of DC buses is inverted to obtain AC power. If it is determined that the charging voltage value of any one of the first group of DC buses and the second group of DC buses is not equal to the first preset voltage value, then the working state of the second type of switch is kept closed, and the DC bus is continued to be charged until the charging voltage value of the DC bus is equal to the first preset voltage value. Determine whether the frequency and phase of the AC current and the target AC current are the same; If it is determined that the frequency and phase of the AC power supply and the target AC power supply are the same, then it is determined whether the voltage difference between the AC power supply and the target AC power supply is equal to the second preset voltage value. If it is determined that the frequency and phase of the AC power supply and the target AC power supply are not the same, then the step of detecting the voltage difference between the AC power supply and the target AC power supply will not be performed. If it is determined that the voltage difference between the AC power supply and the target AC power supply is equal to the second preset voltage value, then the working state of the second type of switch is controlled to be in the open state, so as to realize the disconnection control of the soft start circuit of the three-level converter. If it is determined that the voltage difference between the AC power supply and the target AC power supply is not equal to the second preset voltage value, then the second type of switch is kept in the closed state, and the step of determining whether the voltage difference is equal to the second preset voltage value is continued.

2. The three-level converter soft-start circuit according to claim 1, characterized in that, The circuit also includes: A plurality of resistors, wherein the plurality of resistors includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor; The positive DC terminal of the first rectifier bridge is connected to the first terminal of the first resistor. The negative DC terminal of the first rectifier bridge, the positive DC terminal of the second rectifier bridge, and the first terminal of the second resistor are connected. The negative DC terminal of the second rectifier bridge is connected to the first terminal of the third resistor. The positive DC terminal of the third rectifier bridge is connected to the first terminal of the fourth resistor. The negative DC terminal of the third rectifier bridge, the positive DC terminal of the fourth rectifier bridge, and the first terminal of the fifth resistor are connected. The negative DC terminal of the fourth rectifier bridge is connected to the first terminal of the sixth resistor.

3. The three-level converter soft-start circuit according to claim 2, characterized in that, The circuit also includes: Multiple bus capacitors, wherein the multiple bus capacitors include a first positive bus capacitor, a first negative bus capacitor, a second positive bus capacitor, and a second negative bus capacitor; The second end of the first resistor is connected to the first end of the first positive bus capacitor; the second end of the second resistor, the second end of the first positive bus capacitor, and the first end of the first negative bus capacitor are connected; the second end of the third resistor is connected to the second end of the first negative bus capacitor; the second end of the fourth resistor is connected to the first end of the second positive bus capacitor; the second end of the fifth resistor, the second end of the second positive bus capacitor, and the first end of the second negative bus capacitor are connected; and the second end of the sixth resistor is connected to the second end of the second negative bus capacitor.

4. The three-level converter soft-start circuit according to claim 2, characterized in that, The circuit also includes: A first type of switch is provided between the power distribution source and the split transformer, wherein the first type of switch includes a first switch, a second switch and a third switch, and the second type of switch includes a fourth switch, a fifth switch and a sixth switch; The first output terminal of the power distribution power supply is connected to the first terminal of the first switch, the second terminal of the first switch is connected to the first terminal of the fourth switch, the second terminal of the fourth switch is connected to the first input terminal of the split transformer, the second output terminal of the power distribution power supply is connected to the first terminal of the second switch, the second terminal of the second switch is connected to the first terminal of the fifth switch, the second terminal of the fifth switch is connected to the second input terminal of the split transformer, the third output terminal of the power distribution power supply is connected to the first terminal of the third switch, the second terminal of the third switch is connected to the first terminal of the sixth switch, and the second terminal of the sixth switch is connected to the third input terminal of the split transformer.

5. A control method for a soft-start circuit of a three-level converter, characterized in that, The control method is used to control the soft-start circuit of the three-level converter according to any one of claims 1 to 4, including: AC power is obtained through the power distribution source; The split transformer converts AC power 1 into AC power 2 and AC power 3, wherein the voltage values ​​of AC power 2 and AC power 3 are both greater than the voltage value of AC power 1. The AC power supply 2 and the AC power supply 3 are rectified to obtain DC power supply 1 and DC power supply 2. Charge the DC bus where the bus capacitor is located according to DC power supply one and / or DC power supply two; The operating state of the second type of switch is controlled according to the charging voltage value of the DC bus, so as to realize the control of the soft start circuit of the three-level converter.

6. The method according to claim 5, characterized in that, The DC bus containing the first positive bus capacitor is the first positive DC bus, the DC bus containing the first negative bus capacitor is the first negative DC bus, the DC bus containing the second positive bus capacitor is the second positive DC bus, and the DC bus containing the second negative bus capacitor is the second negative DC bus. The first positive DC bus and the first negative DC bus form a first group of DC buses, and the second positive DC bus and the second negative DC bus form a second group of DC buses. If the DC bus is the first group of DC buses and the second group of DC buses, charging the DC bus containing the bus capacitor according to DC current one and / or DC current two includes: Obtain DC current one and DC current two; The first positive DC bus and the first negative DC bus in the first group of DC buses are charged according to the DC current. The second positive DC bus and the second negative DC bus in the second group of DC buses are charged according to the DC current.

7. The method according to claim 5, characterized in that, When the first group of DC buses and the second group of DC buses are running simultaneously, the operating state of the second type of switch is controlled according to the charging voltage value of the DC buses to achieve control of the soft-start circuit of the three-level converter, including: The charging voltage value of the first group of DC buses is obtained based on the charging voltage difference between the first positive DC bus and the first negative DC bus. Determine whether the charging voltage value of the first group of DC buses is equal to the first preset voltage value; If it is determined that the charging voltage value of the first group of DC buses is equal to the first preset voltage value, then the DC power on the first group of DC buses is inverted to obtain AC power. If it is determined that the charging voltage value of the first group of DC buses is not equal to the first preset voltage value, then the working state of the second type of switch is kept closed, and the DC bus is continued to be charged until the charging voltage value of the DC bus is equal to the first preset voltage value. Determine whether the frequency and phase of the AC current and the target AC current are the same; If it is determined that the frequency and phase of the AC power supply and the target AC power supply are the same, then it is determined whether the voltage difference between the AC power supply and the target AC power supply is equal to the second preset voltage value. If it is determined that the frequency and phase of the AC power supply and the target AC power supply are not the same, then the step of detecting the voltage difference between the AC power supply and the target AC power supply will not be performed. If it is determined that the voltage difference between the AC power supply and the target AC power supply is equal to the second preset voltage value, then the working state of the second type of switch is controlled to be in the open state, so as to realize the disconnection control of the soft start circuit of the three-level converter. If it is determined that the voltage difference between the AC power supply and the target AC power supply is not equal to the second preset voltage value, then the working state of the second type of switch is maintained in the closed state, and the step of determining whether the voltage difference is equal to the second preset voltage value is continued.

8. The method according to claim 5, characterized in that, When the first group of DC buses operates independently, if the DC bus is the first group of DC buses, the operating state of the second type of switch is controlled according to the charging voltage value of the DC bus to realize the control of the soft-start circuit of the three-level converter, including: The charging voltage value of the first group of DC buses is obtained based on the charging voltage difference between the first positive DC bus and the first negative DC bus. Determine whether the charging voltage value of the first group of DC buses is equal to the first preset voltage value; If it is determined that the charging voltage value of the first group of DC buses is equal to the first preset voltage value, then the DC power on the first group of DC buses is inverted to obtain AC power. If it is determined that the charging voltage value of the first group of DC buses is not equal to the first preset voltage value, then the working state of the second type of switch is kept closed, and the DC bus is continued to be charged until the charging voltage value of the DC bus is equal to the first preset voltage value. Determine whether the frequency and phase of the AC current and the target AC current are the same; If it is determined that the frequency and phase of the AC power supply and the target AC power supply are the same, then it is determined whether the voltage difference between the AC power supply and the target AC power supply is equal to the second preset voltage value. If it is determined that the frequency and phase of the AC power supply VI and the target AC power supply are not the same, then the step of detecting the voltage difference between the AC power supply VI and the target AC power supply will not be performed. If it is determined that the voltage difference between the AC power supply and the target AC power supply is equal to the second preset voltage value, then the working state of the second type of switch is controlled to be in the open state, so as to realize the disconnection control of the soft start circuit of the three-level converter. If it is determined that the voltage difference between the AC current and the target AC current is not equal to the second preset voltage value, then the second type of switch is kept in the closed state, and the step of determining whether the voltage difference is equal to the second preset voltage value is continued.

9. The method according to claim 5, characterized in that, Before obtaining AC power from the power distribution source, the method further includes: Trigger the closing commands of the first type of switch and the second type of switch; In response to the closing commands of the first type of switch and the second type of switch, the step of obtaining AC power from the power distribution source is performed.

10. A control device for a soft-start circuit of a three-level converter, characterized in that, The control device is used to control the soft-start circuit of the three-level converter according to any one of claims 1 to 4, including: The first acquisition unit is used to acquire AC power through the power distribution power supply; The first conversion unit is used to convert AC power one into AC power two and AC power three through the split transformer, wherein the voltage values ​​of AC power two and AC power three are both greater than the voltage value of AC power one. The first rectifier unit is used to rectify the AC power supply 2 and the AC power supply 3 to obtain DC power supply 1 and DC power supply 2; The first charging unit is used to charge the DC bus where the DC power supply one and / or the DC power supply two bus capacitors are located. The first control unit is used to control the operating state of the second type of switch according to the charging voltage value of the DC bus, so as to realize the control of the soft start circuit of the three-level converter.

11. A computer-readable storage medium, characterized in that, The storage medium includes a stored program, wherein the program executes the control method for the three-level converter soft-start circuit according to any one of claims 5 to 9.

12. A processor, characterized in that, The processor is used to run a program, wherein the program executes the control method of the three-level converter soft-start circuit according to any one of claims 5 to 9.

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