Variable speed reference-dead zone slow start method of NPC rectifier and terminal equipment

Abstract

The invention is suitable for the technical field of electric vehicle charging control, and provides a speed change reference-dead zone slow start method and terminal equipment of an NPC rectifier, and the method comprises the steps: obtaining a slow start coefficient, a real-time bus voltage sampling value and a bus voltage set value; a real-time bus voltage reference value is obtained by using an NPC three-level rectifier variable-speed reference slow start method; the method comprises the following steps: acquiring time required for each stepping value of a slow start coefficient, a target value of the slow start coefficient, a switching period, a switching period total count value and a target dead zone preset value, acquiring a real-time dead zone stepping value, and gradually approaching the actual dead zone time to the target dead zone preset value by using an NPC three-level rectifier dead zone slow start method and the dead zone stepping value. In the slow starting process of the NPC rectifier, the slow starting speed can be adjusted in a self-adaptive mode according to working condition changes, meanwhile, current impact in the starting process can be effectively prevented, a rectifier system can operate stably, and high robustness is achieved.

Description

Technical Field

[0003] The present invention belongs to the technical field of electric vehicle charging control, and in particular relates to a variable speed reference-dead zone slow starting method of a charging module and a terminal device. Background Art

[0005] The power modules in electric vehicle charging piles or energy storage use rectifiers for AC-DC conversion. Neutral Point Clamped (NPC) three-level rectifiers have the advantages of high output power quality, low switch tube voltage stress and switching loss, so they are often used in AC-DC conversion.

[0006] Traditional three-phase voltage source pulse width modulation rectifiers often adopt a dual closed-loop control strategy (i.e., bus voltage outer loop and input current inner loop). However, during the startup of the PWM rectifier, the bus voltage rises rapidly, resulting in excessive instantaneous impact current, causing the switch tube to bear extremely large current stress, reducing the reliability and safety of system operation. Therefore, it is necessary to study a suitable slow start method to suppress the impact current during startup and make the reference voltage smoothly transition to a given value. Summary of the invention

[0008] In view of this, an embodiment of the present invention provides a variable speed reference-dead zone slow start method and terminal equipment of an NPC rectifier, aiming to solve the problem in the prior art that the instantaneous impact current at startup is too large, and the reference speed cannot be adjusted during the slow start process, resulting in the inability to adapt according to the actual sampling situation during the slow start process. At the same time, it can solve the three-phase four-wire topology. When the three phases are unbalanced, there is a zero-sequence current on the N line during the slow start, which leads to instantaneous overcurrent, unstable slow start process, and output oscillation.

[0009] To achieve the above-mentioned purpose, a first aspect of an embodiment of the present invention provides a variable speed reference-dead zone slow start method for an NPC rectifier, comprising:

[0010] Get the real-time slow start coefficient;

[0011] Get the real-time bus voltage sampling value;

[0012] Get the bus voltage setting value;

[0013] Based on the variable speed reference slow start process of the NPC three-level rectifier, the bus voltage reference slow start speed is affected by the slow start coefficient, the real-time bus voltage sampling value, and the bus voltage setting value;

[0014] Get the time required for each step value of the slow start coefficient;

[0015] Get the total time after the slow start coefficient stabilizes;

[0016] Get the total value of the switching cycle;

[0017] Get the target dead zone preset value;

[0018] The dead zone step value is obtained based on the total time after the slow start coefficient is stabilized, the total value of the switching cycle and the preset value of the target dead zone.

[0019] Based on the dead-zone slow start process of the NPC three-level rectifier, the actual dead-zone time is gradually approached to the target dead-zone preset value.

[0020] A second aspect of an embodiment of the present invention provides a variable speed reference-dead zone slow start device for an NPC rectifier, comprising:

[0021] NPC three-level rectifier variable speed reference slow start module, used for bus voltage reference slow start speed is affected by slow start coefficient and real-time bus voltage sampling value and bus voltage setting value;

[0022] The NPC three-level rectifier dead zone slow start module is used to gradually approach the actual dead zone time to the target dead zone preset value.

[0023] A third aspect of an embodiment of the present invention provides a terminal device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps described in the method for unified communication management of the charging module as described in any of the above embodiments are implemented.

[0024] A fourth aspect of an embodiment of the present invention provides a computer-readable storage medium, comprising: the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, it implements the steps described in the method for unified communication management of the charging module as described in any of the above embodiments.

[0025] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: compared with the prior art, in the process of the slow start of the NPC three-level rectifier, the bus voltage reference value slowly rises to a given value, and the speed of the reference value rise can be adjusted according to the actual value of the real-time current bus voltage, thereby solving the problem of the low adaptability of the reference value rise speed caused by speed stability (i.e., stable rise according to a fixed step value) or speed change (i.e., stable rise according to a preset step value) in the prior art; at the same time, when the NPC three-level rectifier is slowly started, the four switch tubes are complementary to each other, thereby limiting the duty cycle of the outer tube. Since the duty cycle of the inner tube is complementary to that of the inner tube, the duty cycle of the inner tube becomes larger. When the three phases are unbalanced, the three-phase four-wire topology will have zero-sequence current on the N line, resulting in a problem of instantaneous impact overcurrent. By slowly starting the dead zone, the problem of the increase in the duty cycle of the inner tube is effectively solved, so that the conduction time of the inner and outer tubes is very short, thereby solving the instantaneous current impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1 It is a schematic diagram of the implementation flow of the variable speed reference-dead zone slow start method of the NPC rectifier provided by an embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of a three-phase four-wire NPC topology model provided by another embodiment of the present invention;

[0030] Figure 3 It is a schematic block diagram of a three-phase four-wire NPC topology bus voltage outer loop input current inner loop provided by another embodiment of the present invention;

[0031] Figure 4 It is a schematic block diagram of a variable speed reference slow starting method for an NPC rectifier provided by an embodiment of the present invention;

[0032] Figure 5 It is a schematic diagram of a variable speed reference-dead zone slow start device for an NPC rectifier provided by an embodiment of the present invention;

[0033] Figure 6 It is a schematic diagram of a terminal device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0036] In order to illustrate the technical solution of the present invention, a specific embodiment is provided below for illustration.

[0037] Figure 1 The following is a schematic diagram of the implementation flow of the slow start method provided by an embodiment of the invention. For the sake of convenience, only the part related to the embodiment of the invention is shown. The execution subject of the embodiment of the invention may be a terminal device. Figure 1 As shown, the method may include the following steps:

[0038] S101, obtaining a real-time slow start coefficient, a bus voltage sampling value, and a bus voltage setting value.

[0039] In the embodiment of the present invention, an NPC three-level rectifier system is taken as a research object, a slow starting process of the NPC three-level rectifier is considered, and a variable speed reference-dead zone slow starting method of the NPC rectifier is proposed.

[0040] In the embodiment of the present invention, a three-phase four-wire NPC topology is introduced.

[0041] See Figure 2 The three-phase four-wire NPC topology uses an LCL filter, where the grid-side inductor is Lg, the inverter-side inductor is Lf, the filter capacitor is Cf, the three-phase AC is Va, Vb, Vc, the DC-side capacitors are C1 and C2, and the three-phase bridge arm has four switches and two diodes on each bridge arm. For example, the switches of phase A are SA1, SA2, SA3, SA4, and the diodes are DA1 and DA2. The bus voltage (Vbussample) and input AC current (Iasample, Ibsample, Icsample) of the three-phase four-wire NPC system are sampled respectively, and the sampled inductor current is transformed into the abc / dq coordinate to obtain the d-axis input AC current Idsample and the q-axis input AC current Iqsample, and Vbussample, Idsample, and Iqsample are used for closed loop respectively.

[0042] See Figure 3, the bus voltage reference value Vbusset is subtracted from the bus voltage sampling value Vbussample to obtain a first difference. After the first difference is adjusted by PI, a first adjustment value is obtained to form a bus voltage outer loop. Then, the first adjustment value is used as the d-axis reference Idref of the input AC current, and is subtracted from the d-axis sampling value Idsample of the input AC current to obtain a second difference. The second difference PI regulator obtains the second adjustment value. At the same time, the q-axis reference 0 of the input AC current is subtracted from the q-axis sampling value Iqsample of the input AC current to obtain a third difference. The third difference PI regulator obtains the third adjustment value. The second adjustment value and the third adjustment value are subjected to the inverse transformation of dq / abc to obtain the abc three-phase modulation wave, which is compared with the carrier to obtain SPWM modulation. Among them, the SPWM waveform modulation rule when the carrier is compared with the modulation wave, taking phase A as an example: in the positive half cycle of the modulation wave: SA1 and SA3 are complementary and turned on at high frequency, SA2 is always turned on in the positive half cycle, and SA4 is always turned off in the positive half cycle. Negative half cycle of the modulation wave: SA2 and SA4 are turned on at high frequency and complementary, SA3 is turned on in the negative half cycle, and SA1 is turned off in the negative half cycle.

[0043] In one embodiment of the present invention, the above S101 may include the following steps:

[0044] Get the real-time slow start coefficient;

[0045] The sampling circuit constructed by hardware obtains the real-time bus voltage sampling value;

[0046] Get the bus voltage setting value;

[0047] S102: Based on the NPC three-level rectifier variable speed reference slow starting method, obtain a real-time bus voltage reference value.

[0048] In one embodiment of the present invention, the above S102 may include:

[0049] According to the formula , using the real-time slow start coefficient, the real-time bus voltage sampling value, and the bus voltage setting value, obtain the real-time bus voltage reference value.

[0050] Where k is the real-time slow start coefficient, Prek is the target value of the slow start coefficient, is the real-time bus voltage sampling value, is the real-time bus voltage setting value, is the bus voltage reference value, a and b are intermediate variables;

[0051] See also Figure 4, k ranges from 0 to the first preset value, so b ranges from (1, 0), that is, as the slow start coefficient k gradually increases from 0 to the first preset value, the coefficient of b gradually decreases from 1 to 0, and the bus voltage reference value gradually changes from Vbussample to Vbusset, that is, at the beginning, the bus voltage set value is the same as the sampled value, the error between the two is basically 0, and the adjustment duty cycle is very small. As the slow start coefficient increases, the bus voltage reference value gradually becomes the set value, so that the duty cycle gradually increases.

[0052] The a value adjusts the speed of change of the benchmark.

[0053] During the slow start adjustment process, when the bus voltage sampling value Vbussample is lower than the bus voltage setting value Vbusset, the closer Vbussample is to Vbusset, the more positive a value is, and the smaller the positive value is, the larger the final result Vbusref is; the further Vbussample is away from Vbusset, the more positive a value is, and the larger the positive value is, the smaller the final result bus voltage reference value Vbusref is, that is: when Vbussample < Vbusset, the closer the sampling value Vbussample is to Vbusset, the faster the reference change speed is, and the farther the sampling value Vbussample is from Vbusset, the slower the reference change speed is. To put it more simply, when Vbussample is far away from Vbusset, Vbusset can be slower to wait for Vbussample to rise, and when Vbussample catches up and is close to Vbusset, Vbusset can speed up the stepping pace.

[0054] During the adjustment process of the bus voltage sampling value Vbussample, when it is higher than the bus voltage setting value Vbusset, a is a negative value a < 0. For example, if the last bus voltage sampling value Vbussample is 10 higher than the bus voltage setting value Vbusset, then a = -10, ignoring the influence of b, and the final result is the bus voltage reference value Vbusref = Vbusset +10. If the current bus voltage sampling value Vbussample is 5 higher than the bus voltage setting value Vbusset, then a = -5, ignoring the influence of b, and the final result is Vbusref = Vbusset + 5. By comparing the two Vbusref results, it can be seen that the closer the bus voltage sampling value Vbussample is to the bus voltage setting value Vbusset, the smaller the step value of Vbusref rises, and the farther the bus voltage sampling value Vbussample is from the bus voltage setting value Vbusset, the larger the step value of Vbusref rises, which is consistent with the first conclusion.

[0055] In summary, k controls the initial and final values ​​of Vbusref. When the influence of b is ignored, K can make the reference value grow at a uniform speed and step steadily, while b mainly plays a role in regulating the speed of the startup process. When the bus voltage sampling value Vbussample is close to the bus voltage setting value Vbusset, the bus voltage reference value Vbussample slows down. When the bus voltage sampling value Vbussample is less than the bus voltage setting value Vbusset, the bus voltage reference value Vbussample accelerates.

[0056] S103: Obtain the time required for each step value of the slow start coefficient, the target value of the slow start coefficient, the switching cycle, the total value of the switching cycle, and the target dead zone preset value, and obtain the real-time dead zone step value.

[0057] In one embodiment of the present invention, the above S103 may include:

[0058] according to Obtain a dead zone step value using the total time after the slow start coefficient is stabilized, the switching cycle, the total value of the switching cycle, and the target dead zone preset value;

[0059] in, is the first preset value, TimeStep is the time required for each step value of the slow start, Time is the total time after the slow start coefficient is stable, Ts is the switching cycle, PRD is the total value of the switching cycle, PreDB is the target dead zone preset value, and DBStep is the dead zone step value;

[0060] Although the NPC three-level rectifier variable speed reference slow start method can realize the speed regulation of the reference step value during the slow start process, the control process of the NPC three-level rectifier is: complementary conduction of the tubes, for example: the positive half cycle of the modulation wave: SA1 and SA3 are complementary conducted at high frequency, that is, when SA1 is turned on, SA3 is turned off; and when SA3 is turned on, SA1 is turned off; and the closed-loop variable speed reference slow start method can control the duty cycle of the SA1 switch tube, but at this time the duty cycle of the SA3 tube is complementary to the SA1 switch tube. If the duty cycle of the SA1 switch tube is very small, the duty cycle of the SA3 tube will be very large. The duty cycle of the SA3 tube is very large, which will cause the zero-sequence current on the N line to be too large when the three phases are unbalanced, which is also a problem. Therefore, in addition to being able to achieve speed regulation during the slow start process, it is also necessary to reduce the conduction time of the outer tube during the slow start process, and ensure that the conduction time of the inner tube cannot increase accordingly. Therefore, the dead zone slow start method is used, that is, the dead zone time is not fixed, but gradually increases according to the change time of the slow start coefficient k until it stabilizes to the first preset value.

[0061] Specifically, according to the time TimeStep required for each step value of the slow start coefficient and the first preset value , calculate the total time Time after the slow start coefficient stabilizes.

[0062] Specifically, the required number of switching cycles is calculated according to the total time Time after the slow start coefficient is stabilized and the switching cycle Ts.

[0063] Specifically, the required target dead zone difference is calculated according to the total value PRD of the switching cycles and the target dead zone preset value PreDB.

[0064] Specifically, the dead zone step value DBStep of each switching cycle is calculated according to the target dead zone difference and the required number of switching cycles.

[0065] S104: Based on the NPC three-level rectifier dead zone slow start method, the actual dead zone time is gradually approached to the target dead zone preset value by using the dead zone step value.

[0066] Specifically, the total value PRD of the switching cycle is used as the initial value, the target dead zone preset value PreDB is used as the target value, and DBStep is used as the dead zone step value of each switching cycle. Dead zone slow start is performed, and when the target dead zone preset value PreDB is reached, the dead zone time will no longer change.

[0067] By using the variable speed reference-dead zone slow start process of the NPC three-level rectifier in the embodiment of the present invention, it is possible to achieve that during the reference slow start process, the bus voltage reference value is adjusted according to the proximity between the bus voltage sampling value and the bus voltage setting value. The closer the two are, the faster the bus voltage reference value rises, and the farther the two are, the slower the bus voltage reference value rises. The bus voltage reference value can be adjusted according to different application scenarios and working conditions to adapt to the needs of various working conditions. At the same time, in the embodiment of the present invention, the problem that the outer tube duty ratio is relatively small and the inner tube duty ratio is relatively large during the slow start process due to the complementary tubes of the NPC three-level rectifier can be solved by making the inner and outer tube duty ratios relatively small during the slow start process to prevent the inner tube duty ratio from being relatively large, resulting in current overshoot.

[0068] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0069] Corresponding to the above-mentioned slow start method, an embodiment of the present invention provides a slow start system, which has the same beneficial effects as the above-mentioned slow start method. Figure 5 1 is a schematic block diagram of a soft start system provided by an embodiment of the present invention. For ease of description, only the part related to the embodiment of the present invention is shown.

[0070] In an embodiment of the present invention, the slow start system 30 may include a slow start coefficient, a bus voltage sampling value, a bus voltage setting value acquisition module 301, a speed reference slow start speed regulation module 302, a real-time dead zone step value acquisition module 303 and a dead zone slow start module 304.

[0071] Among them, the slow start coefficient, bus voltage sampling value, bus voltage setting value acquisition module 301 is used to obtain the real-time slow start coefficient, real-time bus voltage sampling value and final bus voltage setting value of the power grid;

[0072] The variable speed reference slow start speed regulating module 302 obtains the real-time bus voltage reference value based on the variable speed reference slow start method of the NPC three-level rectifier;

[0073] The real-time dead zone step value acquisition module 303 is used to acquire the time required for each step value of the slow start coefficient, the target value of the slow start coefficient, the switching cycle, the total value of the switching cycle, and the target dead zone preset value, and acquire the real-time dead zone step value;

[0074] The dead zone slow start module 304 uses the dead zone step value to gradually approach the actual dead zone time to the target dead zone preset value based on the dead zone slow start method of the NPC three-level rectifier.

[0075] Optionally, the variable speed reference slow start speed regulating module 302 is further used for:

[0076] According to the formula , using the real-time slow start coefficient, the real-time bus voltage sampling value, and the bus voltage setting value, obtain the real-time bus voltage reference value.

[0077] Where k is the real-time slow start coefficient, Prek is the target value of the slow start coefficient, is the real-time bus voltage sampling value, is the real-time bus voltage setting value, is the bus voltage reference value, a and b are intermediate variables;

[0078] Optionally, the dead zone slow start module 304 is further used for:

[0079] according to Obtain a dead zone step value using the total time after the slow start coefficient is stabilized, the switching cycle, the total value of the switching cycle, and the target dead zone preset value;

[0080] in, is the first preset value, TimeStep is the time required for each step value of the slow start, Time is the total time after the slow start coefficient is stable, Ts is the switching cycle, PRD is the total value of the switching cycle, PreDB is the target dead zone preset value, and DBStep is the dead zone step value;

[0081] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the soft start system can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in one processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned device can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0082] Figure 6 is a schematic block diagram of a terminal device provided by an embodiment of the present invention. Figure 6 As shown, the terminal device 40 of this embodiment includes: one or more processors 401, a memory 402, and a computer program 403 stored in the memory 402 and executable on the processor 401. When the processor 401 executes the computer program 403, the steps in the above-mentioned various slow start method embodiments are implemented, for example Figure 1 Alternatively, when the processor 401 executes the computer program 403, the functions of each module / unit in the above-mentioned slow start system embodiment are realized, for example Figure 5 Functions of modules 301 to 304 are shown.

[0083] Exemplarily, the computer program 403 can be divided into one or more modules / units, and the one or more modules / units are stored in the memory 402 and executed by the processor 401 to complete the present application. The one or more modules / units can be a series of computer program instruction segments that can complete specific functions, and the instruction segments are used to describe the execution process of the computer program 403 in the terminal device 40. For example, the computer program 403 can be divided into a slow start coefficient, a bus voltage sampling value, a bus voltage setting value acquisition module, a speed reference slow start speed regulation module, a real-time dead zone step value acquisition module and a dead zone slow start module. The specific functions of each module are as follows:

[0084] A module for acquiring a slow start coefficient, a bus voltage sampling value, and a bus voltage setting value is used to acquire a real-time slow start coefficient, a real-time bus voltage sampling value, and a final bus voltage setting value of the power grid;

[0085] The variable speed reference slow start speed control module obtains the real-time bus voltage reference value based on the variable speed reference slow start method of the NPC three-level rectifier;

[0086] A real-time dead zone step value acquisition module is used to obtain the time required for each step value of the slow start coefficient, the target value of the slow start coefficient, the switching cycle, the total value of the switching cycle, the target dead zone preset value, and obtain the real-time dead zone step value;

[0087] The dead zone slow start module is based on the NPC three-level rectifier dead zone slow start method and uses the dead zone step value to gradually approach the actual dead zone time to the target dead zone preset value.

[0088] Other modules or units can refer to Figure 5 The description in the illustrated embodiment will not be repeated here.

[0089] The terminal device 40 may be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The terminal device 40 includes but is not limited to a processor 401 and a memory 402. Those skilled in the art will appreciate that Figure 6 It is only an example of the terminal device 40 and does not constitute a limitation of the terminal device 40. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the terminal device 40 may also include an input device, an output device, a network access device, a bus, etc.

[0090] The processor 401 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0091] The memory 402 may be an internal storage unit of the terminal device 40, such as a hard disk or memory of the terminal device 40. The memory 402 may also be an external storage device of the terminal device 40, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the terminal device 40. Further, the memory 402 may also include both an internal storage unit of the terminal device 40 and an external storage device. The memory 402 is used to store the computer program 403 and other programs and data required by the terminal device 40. The memory 402 may also be used to temporarily store data that has been output or is to be output.

[0092] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0093] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0094] In the embodiments provided in the present application, it should be understood that the disclosed slow-start system and method can be implemented in other ways. For example, the slow-start system embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0095] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0096] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0097] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0098] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A variable speed reference-dead zone slow start method for an NPC rectifier, characterized in that: include: Get the real-time slow start coefficient; Get the real-time bus voltage sampling value; Get the bus voltage setting value; Based on the variable speed reference slow start process of the NPC three-level rectifier, the bus voltage reference slow start speed is affected by the slow start coefficient, the real-time bus voltage sampling value, and the bus voltage setting value; Get the time required for each step value of the slow start coefficient; Get the total time after the slow start coefficient stabilizes; Get the total value of the switching cycle; Get the target dead zone preset value; Based on the total time after the slow start coefficient is stabilized, the total value of the switching cycle and the preset value of the target dead zone, the dead zone step value is obtained; Based on the dead-zone slow start process of the NPC three-level rectifier, the actual dead-zone time is gradually approached to the target dead-zone preset value.

2. The variable speed reference-dead zone slow start method of the NPC rectifier according to claim 1, characterized in that: The NPC three-level rectifier variable speed reference slow start process includes: according to The real-time slow start coefficient, the real-time bus voltage sampling value, and the bus voltage setting value are used to obtain a real-time bus voltage reference value. Where k is the real-time slow start coefficient, Prek is the target value of the slow start coefficient, is the real-time bus voltage sampling value, is the real-time bus voltage setting value, is the bus voltage reference value, a and b are intermediate variables.

3. The variable speed reference-dead zone slow start method of the NPC rectifier according to claim 2, characterized in that: The target value Prek of the slow start coefficient is a first preset value.

4. The variable speed reference-dead zone slow start method of the NPC rectifier according to claim 1, characterized in that: The bus voltage setting value is a second preset value.

5. The variable speed reference-dead zone slow start method of the NPC rectifier according to claim 1, characterized in that: The total time after the slow start coefficient is stabilized is calculated according to the time required for each step value of the slow start coefficient and the first preset value.

6. The variable speed reference-dead zone slow start method of the NPC rectifier according to claim 5, characterized in that: The required number of switching cycles is calculated based on the total time after the slow start coefficient is stabilized and the switching cycle.

7. The variable speed reference-dead zone slow start method of the NPC rectifier according to claim 1, characterized in that: The required target dead zone difference is calculated based on the total value of the switching cycles and the preset value of the target dead zone.

8. The variable speed reference-dead zone slow start method of the NPC rectifier according to claims 1 to 7, characterized in that: The dead zone slow start process based on the NPC three-level rectifier includes: according to Obtain a dead zone step value using the total time after the slow start coefficient is stabilized, the switching cycle, the total value of the switching cycle, and the target dead zone preset value; in, is the first preset value, TimeStep is the time required for each step value of the slow start, Time is the total time after the slow start coefficient is stable, Ts is the switching cycle, PRD is the total value of the switching cycle, PreDB is the target dead zone preset value, and DBStep is the dead zone step value.

9. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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