Inverter bypass current sharing control method and inversion system

Abstract

The invention relates to an inverter bypass current sharing control method and an inverter system, the system is used for realizing computing power scheduling, and the inverter bypass current sharing control method comprises the following steps: judging whether a local machine is a host; if the local computer is not the host computer, acquiring the bypass current of the local computer through a current sampling circuit, and acquiring the bypass current of the other computer through parallel communication; the current-sharing control unit calculates a non-current-sharing value of the local bypass current according to the local bypass current and the other bypass current; conducting time of a full-control power device of the bypass circuit is calculated through a software current sharing control algorithm; pulse driving square waves of the full-control power device are generated; and the driving circuit amplifies the driving signal and drives the full-control power device to be switched on. In the field of inverter systems, the problem of current sharing during bypass power supply is always one of technical difficulties in the industry, and the scheme provided by the invention can efficiently solve the problem of current sharing during bypass power supply.

Description

Technical Field

[0001] The present invention relates to the field of inverter systems, and in particular to an inverter bypass current sharing control method and an inverter system. Background Art

[0002] Inverter systems play a vital role in modern power supply, especially in application scenarios that require high reliability and high stability. Inverter systems not only need to ensure power continuity and stability in the main inverter power supply state, but also need to maintain good performance in the bypass power supply state. However, the current sharing problem during bypass power supply has always been one of the technical difficulties in the industry.

[0003] The existing inverter bypass circuit adopts the form of bidirectional thyristor, such as Figure 3 As shown. When the inverter is working in the bypass state, the inverter control unit will issue a command to close the bidirectional thyristor, and the AC power will directly supply power to the load through the bidirectional thyristor, thereby improving the overall operating efficiency. In a multi-inverter parallel system, the thyristors between the inverters have differences in internal resistance, circuit impedance, etc., which will cause the current between the bypasses of each inverter to have uneven current values ​​and bypass circulation. This phenomenon is particularly obvious when the current load is large. The uneven current between the bypasses will cause the inverter system with a smaller overall impedance to bear more load, or even overload. The uneven current between the bypasses reduces the load capacity and overall reliability of the inverter in the bypass working mode.

[0004] In order to avoid the problem of uneven current distribution in the bypass, the existing solution is to add a current distribution inductor to the bypass, such as Figure 4 As shown. The current-sharing inductor can improve the overall impedance of the system and thus reduce the bypass current inequality phenomenon. However, adding the current-sharing inductor from the hardware will bring two disadvantages: one is to reduce the overall operating efficiency of the system; the other is to increase the hardware cost. For the above problems, the existing technology has not yet provided a reasonable solution. Summary of the invention

[0005] The technical problem to be solved by the present invention is: how to design a current sharing control solution. The solution described in this application can efficiently solve the current sharing problem during bypass power supply.

[0006] In order to solve the above problems, the present invention proposes an inverter bypass current sharing control method and an inverter system to reduce the uneven current phenomenon caused by the bypass parallel power supply of multiple inverters. The traditional bypass circuit topology uses a bidirectional thyristor as a power device, and the bidirectional thyristor is a semi-controlled power device, which can only control its conduction but not its shutdown, which brings difficulties to the bypass current sharing control. Therefore, the present invention uses a fully controlled power device and combines it with a unidirectional power device as a bypass circuit topology, and on the basis of achieving bidirectional conduction, the controllability of the circuit on and off is guaranteed.

[0007] The bypass circuit uses Figure 5 Topology, taking single-phase as an example. Fully controlled devices can use metal oxide semiconductor field effect transistors (MOSFETs) or insulated gate bipolar transistors (IGBTs), and unidirectional power devices can use diodes or thyristors (SCRs). Using fully controlled power devices ensures that the on and off of the bypass circuit can be controlled, but since fully controlled power devices generally parasitize a reverse diode, an additional forward unidirectional power device is required. Figure 5 The circuit topology uses MOSFET as a fully controlled power device and a diode as a unidirectional power device.

[0008] In this application, the overall block diagram of the bypass current sharing control system of the inverter system is as follows: Figure 6 As shown. The basic working process of the bypass current sharing control system is: when the multi-inverter system works in bypass, the bypass control system of the single inverter obtains the local bypass current by the current sampling circuit, obtains the bypass current of other machines by the parallel communication, and the current sharing control unit calculates the unbalanced current value △I of the local bypass current according to the local bypass current and the bypass current of other machines. The software current sharing control algorithm calculates the conduction time of the full-controlled power device of the bypass circuit, and generates a pulse drive square wave. The drive circuit amplifies the drive signal and drives the full-controlled power device to conduct. By controlling the conduction time of the full-controlled power device, the local bypass current is controlled to be close to the average bypass current of the parallel system, and finally the current sharing control of the entire parallel system is completed.

[0009] The present application adopts a master-slave control strategy, the host bypass is fixedly turned on, and the slave bypass adjusts the on-time according to the uneven current value. In the first aspect, an embodiment of the present invention proposes an inverter bypass current sharing control method, which is used to implement current sharing control in an inverter system, and the method includes: S1, judging whether the local machine is the host; S2, if the local machine is not the host, the local bypass current is obtained by the current sampling circuit, and the bypass current of the other machine is obtained by the parallel communication; S3, the current sharing control unit calculates the uneven current value of the local bypass current according to the local bypass current and the bypass current of the other machine; S4, the on-time of the fully controlled power device of the bypass circuit is calculated by the software current sharing control algorithm; S5, a pulse drive square wave of the fully controlled power device is generated; S6, the drive circuit amplifies the drive signal and drives the fully controlled power device to turn on.

[0010] Its further technical solution is that after S1 determines whether the machine is a host, the method also includes: S21, if the machine is a host, the control algorithm calculates the conduction time of the fully-controlled power device; S22, generates a pulse drive square wave for the fully-controlled power device; S23, the drive circuit amplifies the drive signal to drive the fully-controlled power device to turn on and off.

[0011] A further technical solution is that, in S3, the current sharing control unit calculates the unbalanced current value of the local bypass current according to the local bypass current and the other machine bypass current, including:

[0012] Calculate the average current I of the parallel system avg ;

[0013]

[0014] Calculate the uneven current value I of the local current diff ;

[0015] I diff =I avg -I self .

[0016] Its further technical solution is that S4, through the software current sharing control algorithm, calculates the conduction time of the fully controlled power device of the bypass circuit, including: S41, adopts the master-slave control strategy, the host bypass is fixedly turned on, and the slave bypass adjusts the conduction time according to the uneven current value, and then calculates the conduction time of the fully controlled power device of the bypass circuit.

[0017] A further technical solution is that the step S41 comprises:

[0018] The host bypass is fixedly turned on, and the slave limits the uneven current value to obtain a first limiting value D1;

[0019] The first limit value D1 is used as a calculation parameter, and the duty cycle adjustment value Da is obtained through calculation by the error elimination controller;

[0020] The duty cycle adjustment value Da is limited to obtain a second limit value D2;

[0021] According to the second limit value D2, the final duty cycle D3 and the value of the on-time T are calculated.

[0022] Further, the calculation of the final duty cycle D3 and the value of the on-time T according to the second limit value D2 includes:

[0023] Calculate the final duty cycle D3;

[0024] D3 = 100% - D2;

[0025] Calculate the conduction time T;

[0026] T=D3×T period ;

[0027] Among them, T period It refers to the control cycle. By configuring the operating cycle of the control chip, the control cycle can be preset.

[0028] In the second aspect, the present application proposes an inverter system, which is used to implement the inverter bypass current sharing control method as described in the first aspect. The performance of the inverter system is better than the existing inverter bypass circuit. The inverter system is connected to the AC power system and the load system. The inverter system also includes N current sharing control systems, and the current sharing control system is provided with a parallel communication unit. The number N is greater than or equal to three, and the N current sharing control systems are interconnected through the parallel communication unit.

[0029] Its further technical solution is that the current balancing control system also includes a bypass circuit, a current sampling circuit, a drive circuit, and a current balancing control unit. The AC power system is connected to the bypass circuit, the load system is connected to the bypass circuit, the bypass circuit is connected to the current sampling circuit, the current sampling circuit is connected to the current balancing control unit, the current balancing control unit is connected to the drive circuit, the drive circuit is connected to the bypass circuit, and the current balancing control unit is also connected to the parallel communication unit, and the interconnection between N current balancing control systems is achieved through the parallel communication.

[0030] Compared with the solution described in the present invention, the existing bypass circuit solution has shortcomings: the traditional bypass circuit topology uses bidirectional thyristors as power devices, and bidirectional thyristors are semi-controlled power devices, which can only control their conduction but not their shutdown, which brings difficulties to bypass current sharing control. Therefore, the present invention uses a fully controlled power device combined with a unidirectional power device as the bypass circuit topology, and ensures the on-off controllability of the circuit on the basis of achieving bidirectional conduction.

[0031] Taking single-phase as an example, the bypass circuit uses a combination of fully controlled devices and unidirectional power devices. Fully controlled devices can use metal oxide semiconductor field effect transistors (MOSFETs) or insulated gate bipolar transistors (IGBTs), and unidirectional power devices can use diodes or thyristors (SCRs). The use of fully controlled power devices can ensure the on-off controllability of the bypass circuit, but because fully controlled power devices generally parasitize a reverse diode, an additional forward unidirectional power device is required.

[0032] The basic working process of the bypass current sharing control system of the inverter system is as follows: when the multi-inverter system works in bypass, the bypass control system of the single inverter obtains the local bypass current through the current sampling circuit, and obtains the bypass current of other machines through parallel communication. The current sharing control unit calculates the uneven current value △I of the local bypass current based on the local bypass current and the bypass current of other machines, calculates the conduction time of the full-controlled power device of the bypass circuit through the software current sharing control algorithm, and generates a pulse drive square wave. The drive circuit amplifies the drive signal and drives the full-controlled power device to turn on. By controlling the conduction time of the full-controlled power device, the local bypass current is controlled to be close to the average bypass current of the parallel system, and finally the current sharing control of the entire parallel system is completed. This application adopts a master-slave control strategy, the host bypass is fixedly turned on, and the slave bypass adjusts the conduction time according to the uneven current value of the current.

[0033] In one embodiment, the fully controlled power device corresponding to the bypass circuit uses an IGBT, and the unidirectional power device uses a diode. The on-duty cycle of the fully controlled device of the host is fixed at 100%, and its on-time is calculated by the duty cycle and the on-cycle time. In the slave control strategy, the controller to eliminate the uneven current value uses a PI controller, that is, a proportional integral controller. The proportional controller can quickly reduce the error to a smaller value, but cannot completely eliminate the error; while the integral controller can eliminate the error, but at a slower speed. Combining the proportional controller with the integral controller can achieve the purpose of quickly eliminating the error.

[0034] In another embodiment, the fully controlled power device corresponding to the bypass circuit uses MOSFET, and the unidirectional power device uses thyristor. When the inverter parallel system works in bypass, the current sharing control unit first determines whether the machine is in the host mode. If it is in the host mode, the host control strategy is used. If the machine is in the slave mode, the slave control strategy is used. The method for eliminating the uneven current value of the current in the slave control strategy can be achieved by table lookup. After the uneven current value of the bypass current of the machine is calculated, the uneven current degree can be further calculated, and the duty cycle adjustment value can be directly obtained by looking up the table based on the uneven current degree. The advantage of using the table lookup method is that the duty cycle adjustment value can be obtained quickly; the disadvantage of using the table lookup method is that the table data needs to be obtained through experiments, which is related to the characteristics of the inverter itself, so the scope of application is relatively small.

[0035] In summary, the inverter system plays a vital role in modern power supply, especially in application scenarios that require high reliability and high stability. The inverter system not only needs to ensure the continuity and stability of power in the main inverter power supply state, but also needs to maintain good performance in the bypass power supply state. The current sharing problem during bypass power supply has always been one of the technical difficulties in the industry. The solution described in this application can efficiently solve the current sharing problem during bypass power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 The main flow chart of the inverter bypass current sharing control method provided in the embodiment of the present invention.

[0039] Figure 2 A sub-flow chart of the inverter bypass current sharing control method provided in an embodiment of the present invention.

[0040] Figure 3 A schematic diagram of an existing inverter bypass circuit using a bidirectional thyristor.

[0041] Figure 4 Schematic diagram of adding a current sharing inductor to an existing inverter bypass circuit.

[0042] Figure 5 A partial schematic diagram of an inverter system provided in an embodiment of the present invention.

[0043] Figure 6 An overall schematic diagram of an inverter system provided by an embodiment of the present invention.

[0044] Figure 7 A control strategy diagram of an inverter system provided in an embodiment of the present invention.

[0045] Figure 8 A control algorithm diagram of an inverter system provided in an embodiment of the present invention.

[0046] Fig. 9 Another control strategy diagram of the inverter system provided in an embodiment of the present invention.

[0047] Fig.10 Another control algorithm diagram of the inverter system provided by an embodiment of the present invention.

[0048] Fig.11 A simplified schematic diagram of the framework of an electronic device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or other features, integers, steps, operations, elements, components and / or combinations thereof.

[0051] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0052] It should be further understood that the term "and / or" used in the present specification and the appended claims refers to one or any combination and all possible combinations of the associated listed items, and includes these combinations.

[0053] As used in this specification and the appended claims, the term "if" may be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if [described condition or event] is detected" may be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0054] In this specification and the attached claims, there may be multiple ways of expressing the same technical feature or professional term, such as adopting different forms of expression such as superordinate generalization, subordinate limitation or synonym replacement; those skilled in the art can clearly understand the substantially same technical meanings pointed to by different ways of expression based on their professional knowledge and in combination with the overall content of the specification and the drawings; the differences between different ways of expression are only reflected in the diversity at the textual level, and do not constitute a substantial modification or limitation of the technical solution, and will not affect the certainty of the scope of protection of the claims of this patent and the full disclosure of the technical content of the specification.

[0055] Example 1

[0056] See also Figures 1 to 10 As shown, Figure 1 and Figure 2 , an inverter bypass current sharing control method is proposed in the embodiment of the present invention, and Figure 3 and Figure 4 The inverter bypass circuit is an existing one. The inverter bypass current sharing control method is used to realize current sharing control in the inverter system, and the method includes: S1, judging whether the local machine is the host machine; S2, if the local machine is not the host machine, the local machine bypass current is obtained by the current sampling circuit, and the bypass current of other machines is obtained by the parallel machine communication; S3, the current sharing control unit calculates the unbalanced current value of the local machine bypass current according to the local machine bypass current and the other machine bypass current; S4, the conduction time of the full-controlled power device of the bypass circuit is calculated by the software current sharing control algorithm; S5, a pulse driving square wave of the full-controlled power device is generated; S6, the driving circuit amplifies the driving signal and drives the full-controlled power device to conduct.

[0057] Its further technical solution is that after S1 determines whether the machine is a host, the method also includes: S21, if the machine is a host, the control algorithm calculates the conduction time of the fully-controlled power device; S22, generates a pulse drive square wave for the fully-controlled power device; S23, the drive circuit amplifies the drive signal to drive the fully-controlled power device to turn on and off.

[0058] A further technical solution is that, in S3, the current sharing control unit calculates the unbalanced current value of the local bypass current according to the local bypass current and the other machine bypass current, including:

[0059] Calculate the average current I of the parallel system avg ;

[0060]

[0061] Calculate the uneven current value I of the local current diff ;

[0062] I diff =I avg -I self .

[0063] Its further technical solution is that S4, through the software current sharing control algorithm, calculates the conduction time of the fully controlled power device of the bypass circuit, including: S41, adopts the master-slave control strategy, the host bypass is fixedly turned on, and the slave bypass adjusts the conduction time according to the uneven current value, and then calculates the conduction time of the fully controlled power device of the bypass circuit.

[0064] A further technical solution is that the step S41 comprises:

[0065] The host bypass is fixedly turned on, and the slave limits the uneven current value to obtain a first limiting value D1;

[0066] The first limit value D1 is used as a calculation parameter, and the duty cycle adjustment value Da is obtained through calculation by the error elimination controller;

[0067] The duty cycle adjustment value Da is limited to obtain a second limit value D2;

[0068] According to the second limit value D2, the final duty cycle D3 and the value of the on-time T are calculated.

[0069] Further, the calculation of the final duty cycle D3 and the value of the on-time T according to the second limit value D2 includes:

[0070] Calculate the final duty cycle D3;

[0071] D3 = 100% - D2;

[0072] Calculate the conduction time T;

[0073] T=D3×T period ;

[0074] Among them, T period It refers to the control cycle. By configuring the operating cycle of the control chip, the control cycle can be preset.

[0075] In the second aspect, the present application proposes an inverter system, which is used to implement the inverter bypass current sharing control method as described in the first aspect. The performance of the inverter system is better than the existing inverter bypass circuit. The inverter system is connected to the AC power system and the load system. The inverter system also includes N current sharing control systems, and the current sharing control system is provided with a parallel communication unit. The number N is greater than or equal to three, and the N current sharing control systems are interconnected through the parallel communication unit.

[0076] Its further technical solution is that the current balancing control system also includes a bypass circuit, a current sampling circuit, a drive circuit, and a current balancing control unit. The AC power system is connected to the bypass circuit, the load system is connected to the bypass circuit, the bypass circuit is connected to the current sampling circuit, the current sampling circuit is connected to the current balancing control unit, the current balancing control unit is connected to the drive circuit, the drive circuit is connected to the bypass circuit, and the current balancing control unit is also connected to the parallel communication unit, and the interconnection between N current balancing control systems is achieved through the parallel communication.

[0077] In one embodiment, the bypass circuit and host control strategy are shown in Figure 7 As shown, the bypass circuit corresponding to the full-controlled power device uses IGBT, and the unidirectional power device uses a diode; the host's full-controlled device conduction duty cycle is fixed at 100%, and its conduction time is calculated by the duty cycle and the conduction cycle time. In this embodiment, the slave control strategy, the corresponding slave current sharing control algorithm block diagram is as follows Figure 8 , its workflow refers to the technical content described in the first aspect of this application.

[0078] When the inverter parallel system works in bypass mode, the current sharing control unit first determines whether the machine is in the master mode. If it is in the master mode, the master control strategy is used. If the machine is in the slave mode, the slave control strategy is used. The controller that eliminates the uneven current value in the slave control strategy adopts a PI controller, which is a proportional integral controller, and its mathematical formula is:

[0079] (K p *err)+∫(K i *err);

[0080] The proportional controller can quickly reduce the error to a smaller value, but it cannot completely eliminate the error; the integral controller can eliminate the error, but its speed is slower; combining the proportional controller with the integral controller can achieve the purpose of quickly eliminating the error.

[0081] In one embodiment, the bypass circuit and host control strategy are shown in Fig. 9As shown, the full-control power device corresponding to the bypass circuit uses MOSFET, and the unidirectional power device uses thyristor; when the inverter parallel system works in bypass, the current sharing control unit first determines whether the machine is in the master mode. If it is in the master mode, the master control strategy is used. If the machine is in the slave mode, the slave control strategy is used.

[0082] The method to eliminate the uneven current value in the slave control strategy can be done by looking up a table. After calculating the uneven current value of the local bypass current, the uneven current degree can be further calculated:

[0083]

[0084] The duty cycle adjustment value can be directly obtained by looking up the table based on the uneven current. The advantage of using the table lookup method is that the duty cycle adjustment value can be obtained quickly; the disadvantage is that the table data needs to be obtained through experiments, which is related to the characteristics of the inverter itself and has a small scope of application.

[0085] In one embodiment, the error elimination controller in the slave control strategy can be implemented in a variety of ways, such as combining the table lookup method with the integral controller, which can further improve the control speed and expand the applicable scope of the table data to a certain extent. Furthermore, the scheme described in the embodiment of the present invention can also be used for single-phase inverters, three-phase four-wire inverters, and three-phase three-wire inverters.

[0086] In summary, the inverter system plays a vital role in modern power supply, especially in application scenarios that require high reliability and high stability. The inverter system not only needs to ensure the continuity and stability of power in the main inverter power supply state, but also needs to maintain good performance in the bypass power supply state. The current sharing problem during bypass power supply has always been one of the technical difficulties in the industry. The solution described in this application can efficiently solve the current sharing problem during bypass power supply.

[0087] Example 2

[0088] See also Fig.11 , Fig.11 The block diagram of an electronic device provided by the present invention. The electronic device can be a terminal or a server, wherein the terminal can be an electronic device with communication function such as a smart phone, a tablet computer, a laptop computer, a desktop computer, a personal digital assistant, and a wearable device. It includes a processor 111, a communication interface 112, a memory 113, and a communication bus 114, wherein the processor 111, the communication interface 112, and the memory 113 communicate with each other through the communication bus 114.

[0089] The memory 113 is used to store computer programs.

[0090] In one embodiment of the present invention, the processor 111 is used to implement the method provided by any one of the aforementioned method embodiments when executing the program stored in the memory 113 .

[0091] It should be understood that in the embodiment of the present application, the processor 111 may be a central processing unit (CPU), and the processor 502 may also be 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. Among them, the general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0092] It is understood by those skilled in the art that all or part of the processes in the method for implementing the above embodiment can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a storage medium, which is a computer-readable storage medium. The computer program is executed by at least one processor in the computer system to implement the process steps of the embodiment of the above method.

[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, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions, but such implementation should not be considered to be beyond the scope of the present invention.

[0094] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of each unit is only a logical function division, and there may be other division methods in actual implementation. For example, units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0095] The steps in the method of the embodiment of the present invention can be adjusted in order, combined and deleted according to actual needs. The units in the device of the embodiment of the present invention can be combined, divided and deleted according to actual needs. In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0096] If the integrated 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 storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, terminal, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention.

[0097] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0098] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0099] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for controlling bypass current sharing of an inverter, characterized in that: The inverter bypass current sharing control method is used for implementing current sharing control in an inverter system, and the method comprises: S1, determine whether this machine is the host; S2, if the local machine is not the host machine, the local machine bypass current is obtained by the current sampling circuit, and the other machine bypass current is obtained by the parallel communication; S3, the current sharing control unit calculates the unbalanced current value of the local bypass current according to the local bypass current and the other machine bypass current; S4, the conduction time of the fully controlled power device of the bypass circuit is calculated by the software current sharing control algorithm; S5, generates a pulse drive square wave for fully controlled power devices; S6, the driving circuit amplifies the driving signal and drives the fully controlled power device to turn on.

2. The inverter bypass current sharing control method according to claim 1, characterized in that: After determining whether the local device is a host in S1, the method further includes: S21, if the machine is the host, the control algorithm calculates the conduction time of the fully controlled power device; S22, generates a pulse drive square wave for fully controlled power devices; S23, the driving circuit amplifies the driving signal to drive the fully controlled power device to turn on and off.

3. The inverter bypass current sharing control method according to claim 1, characterized in that: The current sharing control unit in step S3 calculates the unbalanced current value of the local bypass current according to the local bypass current and the other machine bypass current, including: Calculate the average current I of the parallel system avg ; Calculate the uneven current value I of the local current diff ; I diff =I avg -I self 。 4. The inverter bypass current sharing control method according to claim 3, characterized in that: The S4, which is calculated by the software current sharing control algorithm to obtain the conduction time of the fully controlled power device of the bypass circuit, includes: S41, adopting the master-slave control strategy, the master bypass is fixedly turned on, and the slave bypass adjusts the on-time according to the uneven current value, and then calculates the on-time of the full-control power device of the bypass circuit.

5. The inverter bypass current sharing control method according to claim 4, characterized in that: The step of S41 comprises: The host bypass is fixedly turned on, and the slave limits the uneven current value to obtain a first limiting value D1; The first limit value D1 is used as a calculation parameter, and the duty cycle adjustment value Da is obtained through calculation by the error elimination controller; The duty cycle adjustment value Da is limited to obtain a second limit value D2; According to the second limit value D2, the final duty cycle D3 and the value of the on-time T are calculated.

6. The inverter bypass current sharing control method according to claim 5, characterized in that: The calculation of the final duty cycle D3 and the value of the on-time T according to the second limit value D2 includes: Calculate the final duty cycle D3; D3 = 100% - D2; Calculate the conduction time T; T=D3×T period ; Among them, T period It refers to the control cycle. By configuring the operating cycle of the control chip, the control cycle can be preset.

7. An inverter system, characterized in that: The inverter system is used to implement the inverter bypass current sharing control method as described in any one of claims 1 to 6. The inverter system is connected to the mains system and the load system. The inverter system also includes N current sharing control systems. A parallel communication unit is provided in the current sharing control system. The number N is greater than or equal to three. The N current sharing control systems are interconnected through the parallel communication unit.

8. The inverter bypass current sharing control method according to claim 7, characterized in that: The current balancing control system also includes a bypass circuit, a current sampling circuit, a drive circuit, and a current balancing control unit. The AC power system is connected to the bypass circuit, the load system is connected to the bypass circuit, the bypass circuit is connected to the current sampling circuit, the current sampling circuit is connected to the current balancing control unit, the current balancing control unit is connected to the drive circuit, the drive circuit is connected to the bypass circuit, the current balancing control unit is also connected to the parallel communication unit, and the interconnection between N current balancing control systems is achieved through the parallel communication.

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