Grid-connected current harmonic optimization control method and device, controller and grid-connected converter

Abstract

The invention discloses a grid-connected current harmonic optimization control method and device, a controller and a grid-connected converter, and relates to the technical field of grid-connected control. The grid-connected current harmonic optimization control method comprises the following steps: determining target dead time according to bus voltage of a grid-connected converter; and controlling the grid-connected converter based on the target dead time, the bus voltage, and the grid-connected voltage and the grid-connected current of the grid-connected converter. According to the method, the dead time is dynamically adjusted by detecting the bus voltage of the grid-connected converter, so that the direct connection of complementary conduction switching devices in a direct-current / alternating-current conversion circuit of the grid-connected converter can be prevented, the harmonic content of grid-connected current can be reduced, and the method is simple and easy for engineering implementation.

Description

Technical Field

[0001] This application relates to the field of grid-connected control technology, and in particular to a grid-connected current harmonic optimization control method, device, controller, and grid-connected converter. Background Technology

[0002] In grid-connected control, the DC / AC conversion circuit in the grid-connected converter is mostly controlled using a fixed dead time. To prevent shoot-through in the upper and lower bridge arms of the DC / AC conversion circuit, a relatively large dead time is generally set. However, as the dead time increases, the harmonic content of the grid-connected current also increases, thus affecting the grid connection quality. Summary of the Invention

[0003] This application proposes a grid-connected current harmonic optimization control method, device, controller, and grid-connected converter to prevent the shoot-through of complementary switching devices in the DC / AC conversion circuit of the grid-connected converter by dynamically adjusting the dead time, and to reduce the harmonic content of the grid-connected current.

[0004] In a first aspect, embodiments of this application provide a grid-connected current harmonic optimization control method, the method comprising: determining a target dead time based on the bus voltage of the grid-connected converter; and controlling the grid-connected converter based on the target dead time, the bus voltage, and the grid-connected voltage and grid-connected current of the grid-connected converter.

[0005] In some embodiments, determining the target dead time based on the bus voltage of the grid-connected converter includes: determining the target dead time as a first time when the bus voltage is greater than a first voltage threshold; and determining the target dead time as a second time when the bus voltage is less than a second voltage threshold; wherein the second voltage threshold is less than the first voltage threshold, and the second time is less than the first time.

[0006] In some embodiments, the method further includes: determining a target drive speed based on the bus voltage; and controlling the grid-connected converter based on the target dead time, the target drive speed, the bus voltage, and the grid-connected voltage and grid-connected current of the grid-connected converter.

[0007] In some embodiments, determining the target drive speed based on the bus voltage includes: when the bus voltage is greater than the first voltage threshold, determining the target drive speed as a first speed; when the bus voltage is less than the second voltage threshold, determining the target drive speed as a second speed; wherein the second speed is greater than the first speed.

[0008] In some embodiments, the method further includes: when the bus voltage is greater than the first voltage threshold, first switching the dead time to the first time, and then switching the drive speed to the first speed; when the bus voltage is less than the second voltage threshold, first switching the drive speed to the second speed, and then switching the dead time to the second time.

[0009] In some embodiments, both the first voltage threshold and the second voltage threshold are negatively correlated with the grid-connected current.

[0010] Secondly, embodiments of this application provide a grid-connected current harmonic optimization control device, the device comprising: a determining module, configured to determine a target dead time based on the bus voltage of the grid-connected converter; and a control module, configured to control the grid-connected converter based on the target dead time, the bus voltage, and the grid-connected voltage and grid-connected current of the grid-connected converter.

[0011] In some embodiments, when the determining module determines the target dead time based on the bus voltage of the grid-connected converter, it is specifically configured to: determine the target dead time as a first time when the bus voltage is greater than a first voltage threshold; and determine the target dead time as a second time when the bus voltage is less than a second voltage threshold; wherein the second voltage threshold is less than the first voltage threshold, and the second time is less than the first time.

[0012] Thirdly, embodiments of this application provide a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, it implements the grid-connected current harmonic optimization control method described in the first aspect.

[0013] Fourthly, embodiments of this application provide a controller, including a memory, a processor, and a computer program stored in the memory. When the computer program is executed by the processor, it implements the grid-connected current harmonic optimization control method described in the first aspect.

[0014] Fifthly, embodiments of this application provide a grid-connected converter, including: a DC / AC conversion circuit; and the grid-connected current harmonic optimization control device described in the second aspect, and / or the controller described in the fourth aspect; wherein the grid-connected current harmonic optimization control device and the controller are used to control the DC / AC conversion circuit.

[0015] The grid-connected current harmonic optimization control method, device, controller, and grid-connected converter of this application embodiment detect the bus voltage of the grid-connected converter, adjust the dead time in real time, and control the grid-connected converter based on the adjusted dead time. This can prevent the complementary switching devices in the DC / AC conversion circuit of the grid-connected converter from shoot-through and reduce the grid-connected current harmonic content.

[0016] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0017] Figure 1 This is a flowchart of a grid-connected current harmonic optimization control method according to an embodiment of this application;

[0018] Figure 2 This is a schematic diagram of the structure of a grid-connected converter according to an embodiment of this application;

[0019] Figure 3 This is a flowchart of another embodiment of the grid-connected current harmonic optimization control method of this application;

[0020] Figure 4 This is a flowchart of a specific embodiment of the grid-connected current harmonic optimization control method of this application;

[0021] Figure 5 This is a graph showing the relationship between the voltage threshold and the grid-connected current in one embodiment of this application;

[0022] Figure 6 This is an NPC-type three-level topology diagram according to an embodiment of this application;

[0023] Figure 7 This is a pulse width modulation waveform of an NPC-type grid-connected converter according to an embodiment of this application;

[0024] Figure 8 This is a waveform diagram of Q1 and Q3 driving according to an embodiment of this application;

[0025] Figure 9 This is a structural block diagram of the grid-connected current harmonic optimization control device according to an embodiment of this application;

[0026] Figure 10 This is a structural block diagram of the controller according to an embodiment of this application;

[0027] Figure 11 This is a structural block diagram of the grid-connected converter according to an embodiment of this application. Detailed Implementation

[0028] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0029] The following description, with reference to the accompanying drawings, describes the grid-connected current harmonic optimization control method, apparatus, medium, and controller according to embodiments of this application.

[0030] The switching devices in the DC / AC conversion circuit of a grid-connected converter typically use IGBTs (Insulated-Gate Bipolar Transistors) or MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). In grid-connected control, a fixed dead time is usually used for the DC / AC conversion circuit. To prevent shoot-through in the upper and lower bridge arms of the DC / AC conversion circuit, a relatively large dead time is generally set. However, as the dead time increases, the harmonic content of the grid-connected current also increases, thus affecting the grid connection quality.

[0031] The dead time of a switching transistor is a delay time set to prevent shoot-through of complementary switching devices (such as upper and lower bridge arms). This dead time can cause output voltage distortion, thereby generating harmonics. Current harmonics refer to the frequency components of the output current other than the fundamental frequency. These harmonics can affect power grid quality and need to be suppressed as much as possible.

[0032] To address this, this application proposes a grid-connected current harmonic optimization control method. By detecting the bus voltage of the grid-connected converter and adjusting the dead time in real time, the grid-connected converter is controlled based on the adjusted dead time. This method can prevent the shoot-through of complementary switching devices in the DC / AC conversion circuit of the grid-connected converter and reduce the harmonic content of the grid-connected current.

[0033] Figure 1 This is a flowchart of a grid-connected current harmonic optimization control method according to an embodiment of this application.

[0034] In embodiments of this application, the grid-connected current harmonic optimization control method is used in grid-connected converters. For example... Figure 2 As shown, the grid-connected converter 100 includes a DC / AC conversion circuit 10. The DC / AC conversion circuit 10 can employ NPC (Neutral-point-clamped) three-level topology, ANPC three-level topology, three-phase full-bridge topology, single-phase full-bridge topology, HERIC (Highly Efficient Reliable Inverter Concept), etc. Figure 2 Taking the NPC three-level topology as an example, regardless of the topology used, it includes switching devices such as IGBT transistors and MOSFETs.

[0035] like Figure 1 As shown, the grid-connected current harmonic optimization control method includes:

[0036] S11, determine the target dead time based on the bus voltage of the grid-connected converter.

[0037] As one implementation method, the target dead time can be determined based on the range in which the bus voltage is located.

[0038] Specifically, the target dead time is determined based on the bus voltage of the grid-connected converter, including: when the bus voltage is greater than a first voltage threshold, the target dead time is determined as a first time; when the bus voltage is less than a second voltage threshold, the target dead time is determined as a second time. The second voltage threshold is less than the first voltage threshold, and the second time is less than the first time. The values ​​of the second voltage threshold, the first voltage threshold, the second time, and the first time can be determined based on experiments, operating conditions, etc. To ensure reliable turn-off of the switching devices, if the driving speed of the switching devices remains constant, then the first time and the second time are greater than the turn-off time of the switching devices.

[0039] Optionally, more voltage thresholds can be set for the bus voltage, such as 3 or 4, each corresponding to a different dead time. Taking 3 as an example, when the bus voltage is greater than the first voltage threshold, the target dead time is determined as the first time; when the bus voltage is less than the second voltage threshold, the target dead time is determined as the second time; when the bus voltage is greater than the third voltage threshold but less than the fourth voltage threshold, the target dead time is determined as the third time. The second voltage threshold is less than the third voltage threshold, the fourth voltage threshold is less than the first voltage threshold, the second time is less than the third time, and the third time is less than the first time.

[0040] As another implementation method, a mapping relationship between bus voltage and dead time can be established in advance, such as a one-to-one mapping relationship, which can be stored in tabular form. When in use, the corresponding target dead time can be obtained by looking up the table based on the bus voltage.

[0041] It should be noted that in the above embodiments, the bus voltage and dead time are positively correlated, that is, when the bus voltage is low, the dead time is small, and when the bus voltage is high, the dead time is large.

[0042] S12 controls the grid-connected converter based on the target dead time, bus voltage, and grid-connected voltage and current of the grid-connected converter.

[0043] Specifically, after determining the target dead time, the dead time can be switched to the target dead time. Then, based on the switched dead time, a control signal can be generated according to the bus voltage, grid voltage, and grid current. This control signal is then used to control the DC / AC conversion circuit in the grid-connected converter. Thus, by detecting the bus voltage of the grid-connected converter and adjusting the dead time in real time, and controlling the DC / AC conversion circuit based on the adjusted dead time, shoot-through of complementary switching devices in the DC / AC conversion circuit of the grid-connected converter can be prevented, and the harmonic content of the grid current can be reduced. Furthermore, the entire process is simple and easy to implement in engineering.

[0044] Figure 3 This is a flowchart of a grid-connected current harmonic optimization control method according to another embodiment of this application. Figure 3 As shown, the grid-connected current harmonic optimization control method includes:

[0045] S31, determine the target dead time and target drive speed based on the bus voltage.

[0046] In this embodiment, the implementation method for determining the target dead time based on the bus voltage can be found in the section on... Figure 1 The illustrated embodiment is described below. Similar to determining the target dead time, the method for determining the target drive speed based on the bus voltage may include: interval determination method and table lookup method.

[0047] For the interval determination method, the target driving speed is determined based on the bus voltage, including: when the bus voltage is greater than a first voltage threshold, the target driving speed is determined as a first speed; when the bus voltage is less than a second voltage threshold, the target driving speed is determined as a second speed; wherein the second speed is greater than the first speed.

[0048] The driving speed refers to the speed at which the driving switching device (such as an IGBT) is turned on and off. It can be adjusted by the driving current and driving voltage. For example, the driving current corresponding to the first speed is less than the driving current corresponding to the second speed, and the driving voltage corresponding to the first speed is less than the driving voltage corresponding to the second speed.

[0049] It should be noted that the first time is greater than the turn-off time of the switching device corresponding to the first speed, and the second time is greater than the turn-off time of the switching device corresponding to the second speed.

[0050] S32 controls the grid-connected converter based on the target dead time, target drive speed, bus voltage, and grid-connected voltage and grid-connected current of the grid-connected converter.

[0051] Compared to Figure 1The embodiment shown incorporates consideration of drive speed, adapting the drive speed to the dead time. This not only better ensures control reliability but also reduces grid-connected current harmonic content.

[0052] In some embodiments of this application, the grid-connected current harmonic optimization control method further includes: when the bus voltage is greater than a first voltage threshold, first switching the dead time to a first time, and then switching the drive speed to a first speed; when the bus voltage is less than a second voltage threshold, first switching the drive speed to a second speed, and then switching the dead time to a second time.

[0053] Before the dead time is switched to the first time, the drive speed may be a relatively fast second speed. In this case, switching the dead time back to the first time still ensures reliable turn-off of the switching device. Therefore, after switching the dead time to the first time, the drive speed can be switched to the slower second speed to reduce noise interference. Conversely, if the drive speed is a relatively slow first speed before switching the dead time to the second time, switching the dead time to the second time first might result in the switching device not being fully turned off when the dead time ends. Therefore, before switching the dead time to the second time, the drive speed should be switched to the faster second speed first.

[0054] Specifically, such as Figure 4 As shown, V1 represents the first voltage threshold, Td1 represents the first time, v1 represents the first speed, V2 represents the second voltage threshold, Td2 represents the second time, and v2 represents the second speed. The switching process between dead time and drive speed includes:

[0055] S41, Begin;

[0056] S42, determine whether the bus voltage is greater than V1;

[0057] If yes, proceed to the next step; otherwise, proceed to step S45.

[0058] S43, switch dead time is Td1;

[0059] S44, switch driver speed to v1;

[0060] S45, determine whether the bus voltage is less than V2;

[0061] If yes, proceed to the next step; otherwise, proceed to step S48.

[0062] S46, switch drive speed to v2;

[0063] S47, switch dead time is Td2;

[0064] S48, End.

[0065] In some embodiments of this application, both the first voltage threshold and the second voltage threshold are negatively correlated with the grid-connected current.

[0066] The grid-connected current can be determined based on the three-phase grid currents iL_a, iL_b, and iL_c. It can be the maximum value among the three-phase grid currents iL_a, iL_b, and iL_c, or it can be the average of the effective values ​​of iL_a, iL_b, and iL_c.

[0067] As one implementation method, the relationship between the first voltage threshold, the second voltage threshold, and the grid-connected current is as follows: Figure 5 As shown, both the first and second voltage thresholds are linearly negatively correlated with the grid-connected current.

[0068] See Figure 5 As the grid-connected current increases, the bus voltage switching threshold (i.e., the first voltage threshold V1 and the second voltage threshold V2) gradually decreases. The interval between V1 and V2 is called the hysteresis interval. The first voltage threshold V1 varies in the range of [V1_min, V1_max], and the second voltage threshold V2 varies in the range of [V2_min, V2_max], and V2_max is less than V1_min.

[0069] Optionally, the first voltage threshold and the second voltage threshold may also have a gradient negative correlation with the grid-connected current. For example, the current range can be divided into a first current range, a second current range, and a third current range from small to large, with the voltage threshold of the first current range being greater than that of the second current range, and the voltage threshold of the second current range being greater than that of the third current range.

[0070] To facilitate understanding, the following will be combined with Figure 2 , Figure 6 , Figure 7 , Figure 8 Taking the DC / AC converter circuit 10 using the NPC three-level topology as an example, the principle of the grid-connected current harmonic optimization control method of this application embodiment is explained.

[0071] See Figure 2 The control chip samples the grid-connected voltage (Ugrid_a, Ugrid_b, Ugrid_c), grid-connected current (iL_a, iL_b, iL_c), and bus voltage (Ubus). After adjustment by the algorithm, it outputs a drive signal to the switching transistors (Q1, Q2, Q3, Q4) and simultaneously controls the grid-connected relay to connect to the power grid.

[0072] Figure 6 The diagram shows the NPC three-level topology used in the DC / AC conversion circuit of the grid-connected converter, and its drive waveform is as follows. Figure 7As shown. During the positive half-cycle of the grid voltage, Q1 / Q3 are chopped at high frequency (complementary), Q2 is turned on, and Q4 is turned off; during the negative half-cycle of the grid voltage, Q2 / Q4 are chopped at high frequency (complementary), Q3 is turned on, and Q1 is turned off.

[0073] Due to the presence of stray inductance in actual circuits ( Figure 2 Stray parameters (not shown in the diagram) cause a voltage superposition due to these stray parameters when the switching transistor operates. Therefore, the total voltage across the switching transistor is half the bus voltage (i.e., Ubus / 2) plus the voltage superposition caused by stray parameters, and its magnitude is shown in the following formula:

[0074] v sum (t)=v L (t)+v platform (t)

[0075] Where Vsum(t) represents the total voltage across the switching transistor, Vplatform(t) represents the half-bus voltage, and VL(t) represents the voltage superposition caused by stray inductance, as shown in the following equation:

[0076]

[0077] It is known that when the current is constant, the faster the driving speed (i.e., the smaller dt), the greater the voltage superposition caused by stray parameters. This is especially true when the switching transistor is turned on to off, where there is often greater stress. Therefore, when designing the switching transistor's turn-on and turn-off drive circuits, the turn-off speed is made slower than the turn-on speed. Thus, the dead time can be determined by the reliable turn-off time of the switching transistor. Based on the above considerations, for NPC-type three-level topologies, Q1 / Q3 and Q2 / Q4 transistors need to have a dead time. During the dead time, the switching transistors do not operate; otherwise, one switching transistor would bear the full bus voltage, causing damage. For example, during the positive half-cycle of the mains voltage, when Q1 is turned on, Q2 is not yet turned off. At this time, Q1 / Q2 / Q3 are conducting, and only Q4 is turned off, bearing the full bus voltage, causing overvoltage damage to switching transistor Q4.

[0078] Figure 8 The diagram shows the driving waveforms of transistors Q1 and Q3 after adding dead time. It can be seen that introducing dead time shortens the turn-on time. During the dead time, the switching transistors do not operate, causing a deviation between the actual output pulse width and the theoretical value, especially at low modulation ratios. This deviation will cause voltage errors, which in turn will lead to an increase in current harmonics.

[0079] As shown above, when Vplatform(t) is low, a smaller dead time can be used, and a faster drive speed can also be used, while the total stress Vsum(t) will not exceed the specifications of the switching transistor, thereby optimizing the harmonics caused by the dead time.

[0080] Figure 9 This is a structural block diagram of the grid-connected current harmonic optimization control device according to an embodiment of this application.

[0081] like Figure 9 As shown, the grid-connected current harmonic optimization control device 20 includes: a determination module 21 and a control module 22.

[0082] The determining module 21 is used to determine the target dead time based on the bus voltage of the grid-connected converter. The control module 22 is used to control the grid-connected converter based on the target dead time, the bus voltage, and the grid-connected voltage and grid-connected current of the grid-connected converter.

[0083] In one implementation, when determining the target dead time based on the bus voltage of the grid-connected converter, the determining module 21 is specifically used to: determine the target dead time as a first time when the bus voltage is greater than a first voltage threshold; and determine the target dead time as a second time when the bus voltage is less than a second voltage threshold; wherein the second voltage threshold is less than the first voltage threshold, and the second time is less than the first time.

[0084] In some embodiments of this application, the determining module 21 is further configured to determine the target drive speed based on the bus voltage; the control module 22 is further configured to control the grid-connected converter based on the target dead time, the target drive speed, the bus voltage, and the grid-connected voltage and grid-connected current of the grid-connected converter.

[0085] In one implementation, when determining the target driving speed based on the bus voltage, the determining module 21 is specifically used to: determine the target driving speed as a first speed when the bus voltage is greater than a first voltage threshold; and determine the target driving speed as a second speed when the bus voltage is less than a second voltage threshold; wherein the second speed is greater than the first speed.

[0086] In some embodiments of this application, the control module 22 is further configured to: when the bus voltage is greater than a first voltage threshold, first switch the dead time to a first time, and then switch the drive speed to a first speed; when the bus voltage is less than a second voltage threshold, first switch the drive speed to a second speed, and then switch the dead time to a second time.

[0087] In some embodiments of this application, both the first voltage threshold and the second voltage threshold are negatively correlated with the grid-connected current.

[0088] It should be noted that for other specific implementations of the grid-connected current harmonic optimization control device 20 in this application embodiment, please refer to the specific implementations of the grid-connected current harmonic optimization control method in the above embodiment.

[0089] Based on the grid-connected current harmonic optimization control method of the above embodiments, this application proposes a computer-readable storage medium.

[0090] In the embodiments of this application, a computer program is stored on a computer-readable storage medium. When the computer program is executed by a processor, it implements the grid-connected current harmonic optimization control method of the above embodiments.

[0091] Figure 10 This is a structural block diagram of the controller according to an embodiment of this application.

[0092] like Figure 10 As shown, the controller 500 includes a processor 501 and a memory 503. The processor 501 and the memory 503 are connected, for example, via a bus 502. Optionally, the controller 500 may also include a transceiver 504. It should be noted that in practical applications, the transceiver 504 is not limited to one type, and the structure of the controller 500 does not constitute a limitation on the embodiments of this application.

[0093] Processor 501 may be a CPU (Central Processing Unit), a general-purpose processor, a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this application. Processor 501 may also be a combination that implements computational functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc.

[0094] Bus 502 may include a pathway for transmitting information between the aforementioned components. Bus 502 may be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. Bus 502 can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 10 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0095] The memory 503 stores a computer program corresponding to the grid-connected current harmonic optimization control method of the above embodiments of this application. This computer program is executed by the processor 501. The processor 501 executes the computer program stored in the memory 503 to implement the content shown in the aforementioned method embodiments.

[0096] The controller 500 includes, but is not limited to, a CPU (Central Processing Unit), such as... Figure 2 The control chip shown. Figure 10 The controller 500 shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0097] Figure 11 This is a structural block diagram of the grid-connected converter according to an embodiment of this application.

[0098] like Figure 11 As shown, the grid-connected converter 100 includes: a DC / AC conversion circuit 10; and a grid-connected current harmonic optimization control device 20 as described in the above embodiment, and / or, a controller 500 as described in the above embodiment. Figure 11 (The example shown includes controller 500). The grid-connected current harmonic optimization control device 20 and controller 500 are used to control the DC / AC conversion circuit 10.

[0099] For example, the DC / AC converter circuit 10 adopts an NPC three-level topology.

[0100] In summary, the grid-connected current harmonic optimization control method, device, controller, and grid-connected converter of this application, by detecting the bus voltage of the grid-connected converter and adjusting the dead time in real time, and controlling the DC / AC conversion circuit in the grid-connected converter based on the adjusted dead time, can not only prevent the complementary switching devices in the DC / AC conversion circuit of the grid-connected converter from shoot-through, but also reduce the grid-connected current harmonic content. Moreover, the solution is simple and easy to apply in engineering.

[0101] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0102] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0103] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0104] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0105] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0106] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0107] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0108] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A grid-connected current harmonic optimization control method, characterized in that, The method includes: Determine the target dead time based on the bus voltage of the grid-connected converter; The grid-connected converter is controlled based on the target dead time, the bus voltage, and the grid-connected voltage and grid-connected current of the grid-connected converter.

2. The grid-connected current harmonic optimization control method according to claim 1, characterized in that, Determining the target dead time based on the bus voltage of the grid-connected converter includes: When the bus voltage is greater than the first voltage threshold, the target dead time is determined as the first time. When the bus voltage is less than the second voltage threshold, the target dead time is determined as the second time; Wherein, the second voltage threshold is less than the first voltage threshold, and the second time is less than the first time.

3. The grid-connected current harmonic optimization control method according to claim 2, characterized in that, The method further includes: The target drive speed is determined based on the bus voltage. The grid-connected converter is controlled based on the target dead time, the target drive speed, the bus voltage, and the grid-connected voltage and grid-connected current of the grid-connected converter.

4. The grid-connected current harmonic optimization control method according to claim 3, characterized in that, Determining the target drive speed based on the bus voltage includes: When the bus voltage is greater than the first voltage threshold, the target driving speed is determined to be the first speed; When the bus voltage is less than the second voltage threshold, the target driving speed is determined to be the second speed; The second speed is greater than the first speed.

5. The grid-connected current harmonic optimization control method according to claim 4, characterized in that, The method further includes: When the bus voltage is greater than the first voltage threshold, the dead time is first switched to the first time, and then the drive speed is switched to the first speed. When the bus voltage is less than the second voltage threshold, the drive speed is first switched to the second speed, and then the dead time is switched to the second time.

6. The grid-connected current harmonic optimization control method according to any one of claims 2-5, characterized in that, Both the first voltage threshold and the second voltage threshold are negatively correlated with the grid-connected current.

7. A grid-connected current harmonic optimization control device, characterized in that, The device includes: The determination module is used to determine the target dead time based on the bus voltage of the grid-connected converter; The control module is used to control the grid-connected converter based on the target dead time, the bus voltage, and the grid-connected voltage and grid-connected current of the grid-connected converter.

8. The grid-connected current harmonic optimization control device according to claim 7, characterized in that, When determining the target dead time based on the bus voltage of the grid-connected converter, the determining module is specifically used for: When the bus voltage is greater than the first voltage threshold, the target dead time is determined as the first time. When the bus voltage is less than the second voltage threshold, the target dead time is determined as the second time; Wherein, the second voltage threshold is less than the first voltage threshold, and the second time is less than the first time.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the grid-connected current harmonic optimization control method as described in any one of claims 1-6.

10. A controller, characterized in that, It includes a memory, a processor, and a computer program stored in the memory, wherein when the computer program is executed by the processor, it implements the grid-connected current harmonic optimization control method as described in any one of claims 1-6.

11. A grid-connected converter, characterized in that, include: DC / AC converter circuit; as well as The grid-connected current harmonic optimization control device as described in claim 7 or 8, and / or the controller as described in claim 10; The grid-connected current harmonic optimization control device and the controller are used to control the DC / AC conversion circuit.

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