Networking system based on inverter

Abstract

The invention provides an inverter-based networking system, and relates to the technical field of power electronic conversion, the inverter-based networking system comprises a first inverter, a second inverter, a dynamic phase line configuration unit, a load and / or a power grid, the first inverter comprises a first phase line, a second phase line and a first neutral line, and the second inverter comprises a third phase line, a fourth phase line and a second neutral line; the dynamic phase line configuration unit is used for configuring the at least one phase line as a phase line of a load and / or a power grid; and connecting the first neutral line and the second neutral line and then configuring the first neutral line and the second neutral line as a neutral line of a load and / or a power grid. The first inverter is used for controlling the output voltage among the first phase line, the second phase line and the neutral line or controlling the grid-connected current of the first phase line and / or the second phase line according to the working mode, and the second inverter is used for controlling the output voltage among the third phase line, the fourth phase line and the neutral line or controlling the grid-connected current of the third phase line and / or the fourth phase line. The networking system can adapt to various user scene requirements.

Description

Technical Field

[0001] The present application relates to the field of power electronic conversion technology, and in particular to an inverter-based networking system. Background Art

[0002] In some areas, household user loads mainly include single-phase devices (such as 120V single-phase devices and 240V single-phase devices), so user energy storage deployment is usually a single-phase three-wire inverter.

[0003] However, some home users may also have three-phase loads (such as 208V three-phase equipment), so users need to deploy additional three-phase inverters, resulting in higher costs. Summary of the Invention

[0004] The embodiments of the present application provide an inverter-based networking system that can adapt to various user scenario requirements and reduce usage costs for home users.

[0005] In some embodiments of the present application, the inverter-based networking system includes: a first inverter, a second inverter, a dynamic phase line configuration unit, a load and / or a power grid, wherein the load includes at least one of a three-phase load, a line-to-line single-phase load, and a line-to-neutral single-phase load;

[0006] The first inverter includes a first phase line, a second phase line, and a first neutral line, and the second inverter includes a third phase line, a fourth phase line, and a second neutral line;

[0007] The dynamic phase line configuration unit is used to configure at least one phase line among the first phase line, the second phase line, the third phase line and the fourth phase line as a phase line of the load and / or the power grid; and after connecting the first neutral line and the second neutral line, configure them as the neutral line of the load and / or the power grid;

[0008] The first inverter is used to control the output voltage between the first phase line, the second phase line and the above-mentioned neutral line, or control the grid-connected current of the first phase line and / or the second phase line according to the working mode of the networking system; the second inverter is used to control the output voltage between the third phase line, the fourth phase line and the above-mentioned neutral line, or control the grid-connected current of the third phase line and / or the fourth phase line according to the above-mentioned working mode.

[0009] In a possible implementation, the operating mode of the networking system includes a first mode; and the dynamic phase line configuration unit is configured to perform at least one of the following:

[0010] Configuring the first phase line, the second phase line, and the third phase line as phase lines of a three-phase load;

[0011] Configuring the third phase line and the fourth phase line as phase lines of line-to-line single-phase loads;

[0012] The fourth phase line is configured as a phase line of a line-neutral single-phase load.

[0013] In one possible implementation, the first inverter is configured to: determine target voltage values ​​of the first phase line and the second phase line, control the output voltage between the first phase line, the second phase line, and the neutral line according to the target voltage values ​​of the first phase line and the second phase line; and send the target voltage value of the first phase line to the second inverter;

[0014] The second inverter is used to: determine the target voltage values ​​of the third phase line and the fourth phase line based on the target voltage value of the first phase line, and control the output voltage between the third phase line, the fourth phase line and the above-mentioned neutral line according to the target voltage values ​​of the third phase line and the fourth phase line.

[0015] In one possible implementation, the operating mode of the networking system includes the second mode; and the dynamic phase line configuration unit is configured to perform at least one of the following:

[0016] Configuring the first phase line, the second phase line, and the third phase line as phase lines of a power grid;

[0017] The fourth phase line is configured as a phase line of a line-neutral single-phase load.

[0018] In one possible implementation, the first inverter is further configured to: determine a grid phase sequence and a phase angle of a first phase line, determine a phase angle of a second phase line and a phase angle of a third phase line according to a positive or negative phase sequence, and control a grid-connected current of the first phase line and the second phase line according to the phase angles of the first phase line and the second phase line, the sampled currents of the first phase line and the second phase line, and a grid angular frequency; and send the phase angle of the third phase line and the above-mentioned grid angular frequency to the second inverter;

[0019] The second inverter is further used to: control the grid-connected current of the third phase line based on the phase angle of the third phase line, the sampled current of the third phase line, and the grid angular frequency obtained by the first inverter; determine the target voltage value of the fourth phase line based on the phase angle of the third phase line, and control the output voltage between the fourth phase line and the above-mentioned neutral line based on the target voltage value of the fourth phase line.

[0020] In a possible implementation, the first inverter is a master inverter, and the second inverter is a slave inverter.

[0021] In one possible implementation, the first inverter includes a first grid interface, a second grid interface, a first grid-connected switch, a second grid-connected switch, a first load interface, a second load interface, a first load switch, and a second load switch; the first grid-connected switch is connected in series between the first phase line and the first grid interface, the second grid-connected switch is connected in series between the second phase line and the second grid interface, the first load switch is connected in series between the first phase line and the first load interface, and the second load switch is connected in series between the second phase line and the second load interface;

[0022] The second inverter includes a third grid interface, a fourth grid interface, a third grid-connected switch, a fourth grid-connected switch, a third load interface, a fourth load interface, a third load switch and a fourth load switch; the third grid-connected switch is connected in series between the third phase line and the third grid interface, the fourth grid-connected switch is connected in series between the fourth phase line and the fourth grid interface, the third load switch is connected in series between the third phase line and the third load interface, and the fourth load switch is connected in series between the fourth phase line and the fourth load interface.

[0023] In one possible implementation, the operating mode of the networking system includes a third mode; and the dynamic phase line configuration unit is configured to perform at least one of the following:

[0024] Connecting any three of the first grid interface, the second grid interface, the third grid interface, and the fourth grid interface to a phase line of a grid;

[0025] Connecting the first load interface, the second load interface, and the third load interface to the phase lines of the three-phase load;

[0026] Connect the fourth load interface to the phase line of a line-neutral single-phase load.

[0027] In one possible implementation, the third mode includes a grid-connected mode and an off-grid mode;

[0028] In the grid-connected mode, the first grid-connected switch, the second grid-connected switch, the third grid-connected switch, the fourth grid-connected switch, the first load switch, the second load switch, the third load switch, and the fourth load switch are all in a closed state;

[0029] In the off-grid mode, the first grid-connected switch, the second grid-connected switch, the third grid-connected switch and the fourth grid-connected switch are all in the open state; the first load switch, the second load switch, the third load switch and the fourth load switch are all in the closed state.

[0030] The inverter-based networking system provided in the embodiment of the present application can perform different phase line configurations according to the different loads or grid scenarios of household users, and realize multiple voltage outputs, including two single-phase voltage levels and one three-phase voltage level output at the same time, which can meet the diverse load requirements of household users and reduce the usage costs of household users. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0032] Figure 1 A schematic diagram of a typical topology of a single-phase three-wire inverter provided in an embodiment of the present application;

[0033] Figure 2 This is a schematic diagram of the architecture of an inverter-based networking system provided in an embodiment of the present application;

[0034] Figure 3 A schematic diagram of a parallel network architecture of two single-phase three-wire inverters provided in an embodiment of the present application;

[0035] Figure 4 This is another schematic diagram of a parallel network architecture of two single-phase three-wire inverters provided in an embodiment of the present application;

[0036] Figure 5 This is a schematic diagram of a parallel network architecture of N single-phase three-wire inverters provided in an embodiment of the present application;

[0037] Figure 6 A schematic diagram of a single-phase three-wire and three-phase four-wire off-grid output mode architecture provided in an embodiment of the present application;

[0038] Figure 7 A schematic diagram of an output voltage control loop provided in an embodiment of the present application;

[0039] Figure 8 A phase diagram of a single-phase three-wire and three-phase four-wire off-grid output mode provided in an embodiment of the present application;

[0040] Figure 9 A schematic diagram of a three-phase four-wire grid-connected and single-phase off-grid hybrid output mode provided in an embodiment of the present application;

[0041] Figure 10 This is another output voltage control loop schematic provided in an embodiment of the present application;

[0042] Figure 11 This is a schematic diagram of a three-phase four-wire parallel-off-grid and single-phase off-grid mixed output mode provided in an embodiment of the present application.

[0043] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0044] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0045] To facilitate a clear description of the technical solutions of the embodiments of this application, the words "exemplary," "for example," and the like are used in the embodiments of this application to indicate examples, illustrations, or explanations. Any embodiment or design described in this application as "exemplary" or "for example" should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0046] In the embodiments of the present application, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and subsequent associated objects are in an "or" relationship.

[0047] An inverter is a power electronic device that converts direct current (DC) into alternating current (AC). Its core function is to convert the input DC voltage into an AC output with adjustable frequency and amplitude through the rapid on-off control of semiconductor switching devices. It has been widely used in new energy power generation, electric vehicles, industrial drives, household appliances and other fields.

[0048] The inverter can achieve DC to AC conversion through the following steps:

[0049] S1. Rectification and filtering (in some scenarios): If the input is AC (such as mains electricity), it must first be converted to DC through a rectifier and then filtered by a capacitor to obtain a stable DC voltage.

[0050] S2. Inverter circuit: The core part is the inverter bridge (such as full-bridge or half-bridge topology), which chops the DC voltage into a high-frequency pulse sequence by controlling the on and off of the switching devices.

[0051] S3, filtering and voltage regulation: After the pulse sequence is smoothed by the LC filter, the output is a sinusoidal AC power. The duty cycle is adjusted through Pulse-Width Modulation (PWM) technology, which can accurately control the output voltage amplitude and frequency.

[0052] S4. Control and protection: The built-in microprocessor monitors voltage, current, temperature and other parameters in real time, and has protection functions such as overvoltage, overcurrent, short circuit and overtemperature.

[0053] In some areas, household user loads mainly include single-phase devices (such as 120V single-phase devices and 240V single-phase devices), so user energy storage deployment is usually 120 / 240V single-phase three-wire inverter.

[0054] For example, refer to Figure 1 , Figure 1 This is a typical topology diagram of a single-phase three-wire inverter provided in an embodiment of the present application.

[0055] The above-mentioned single-phase three-wire inverter includes a DC input side (BUS+ and BUS-), multiple switching tubes, diodes, and components such as inductors and capacitors.

[0056] In addition, the above-mentioned single-phase three-wire inverter further includes:

[0057] N line: Neutral line, which is drawn from the center tap of the inverter output filter circuit and provides a potential reference point for the entire circuit, usually close to the earth potential (the same potential as the earth in the grounding system).

[0058] Lines L1 and L2: These two lines are the live lines, carrying inverted and filtered AC power. They have the same voltage amplitude relative to the neutral line, but the phase relationship depends on the inverter's specific design and operating mode. In some applications, the voltages output by L1 and L2 are equal in magnitude and opposite in phase relative to the neutral line; in other applications, they can output different voltage levels to accommodate varying load requirements.

[0059] However, some users may also have three-phase loads (such as 208V). In this case, if users deploy an additional three-phase inverter, the cost will be high. Therefore, how to obtain three-phase power through the existing 120 / 240V single-phase three-wire inverter is a technical problem that needs to be solved urgently.

[0060] In response to the above technical problems, the embodiments of the present application provide an inverter-based networking system, specifically a parallel networking system based on single-phase three-wire inverters. Different phase line configurations can be performed according to the user's different loads or power grid scenarios, and in conjunction with corresponding control methods, the voltage output required by the user can be achieved, including the simultaneous output of up to two single-phase voltage levels and one three-phase voltage level, which can meet the user's diverse load requirements. For example, through dynamic phase line configuration and in conjunction with corresponding control algorithms, it is possible to achieve the simultaneous output of 120V single-phase, 240V single-phase, and 208V three-phase, that is, to simultaneously obtain 120 / 240V single-phase three-wire power and 120 / 208V three-phase power, thereby meeting the various load application requirements of home users.

[0061] Among them, the control method of the half-bridge inverter can be adopted for control. By adjusting the control voltage target value in the off-grid output voltage control loop, or adjusting the phase angle in the grid-connected current control loop, single-phase and three-phase voltages that meet the target requirements can be obtained.

[0062] The inverter-based networking system provided by the embodiment of the present application is described in detail below through specific implementation methods. It should be noted that the following embodiments can exist independently or in combination with each other, and the same or similar content will not be repeated in different embodiments.

[0063] For example, refer to Figure 2 , Figure 2 This is a schematic diagram of the architecture of an inverter-based networking system provided in an embodiment of the present application.

[0064] In some embodiments, the networking system includes: a first inverter 201, a second inverter 202, a dynamic phase line configuration unit 203, a load and / or a power grid 204, wherein the load includes at least one of a three-phase load, a line-to-line single-phase load, and a line-neutral single-phase load.

[0065] The first inverter 201 includes a first phase line and a second phase line (ie Figure 2 The second inverter 202 includes a third phase line and a fourth phase line (ie, Figure 2 Phase lines L1 and L2 connected to the second inverter 202).

[0066] The dynamic phase line configuration unit 203 is configured to configure at least one phase line among the first phase line, the second phase line, the third phase line, and the fourth phase line as a phase line of the load and / or the power grid 204 .

[0067] For example, the dynamic phase line configuration unit 203 may configure the first, second, and third phase lines as phase lines A, B, and C of the three-phase load or power grid, and configure the fourth phase line as phase line Aux of the line-neutral single-phase load.

[0068] In some embodiments, the first inverter 201 includes a first neutral line (ie Figure 2 The second inverter 202 includes a second neutral line (i.e. Figure 2 N line connected to the second inverter 202).

[0069] The dynamic phase line configuration unit 203 is used to connect the neutral line of the first inverter 201 and the neutral line of the second inverter 202 to configure them as the neutral line N of the load and / or the grid 204 .

[0070] The first inverter 201 is used to control the output voltage between the first phase line and the neutral line N, and the output voltage between the second phase line and the neutral line N according to the working mode of the networking system; or to control the grid-connected current of the first phase line and / or the second phase line.

[0071] The second inverter 202 is used to control the output voltage between the third phase line and the neutral line N, and the output voltage between the fourth phase line and the neutral line N according to the above working mode; or control the grid-connected current of the third phase line and / or the fourth phase line.

[0072] In some embodiments, the networking system further includes a host computer; the host computer is communicatively connected to the first inverter and the second inverter.

[0073] In some implementations, the host computer may be configured to send instruction information to the first inverter and the second inverter, where the instruction information is configured to indicate an operating mode of the networking system.

[0074] In the following embodiments, the first inverter may be referred to as a master or “inverter-M”, and the second inverter may be referred to as a slave or “inverter-S”.

[0075] For example, refer to Figure 3 , Figure 3 This is a schematic diagram of a parallel networking architecture of two single-phase three-wire inverters provided in an embodiment of the present application.

[0076] In some embodiments, the host computer is in communication with the inverter-M and the inverter-S via a bus (e.g., CANH and CANL). CANH and CANL are two physical signal lines on a controller area network (CAN) bus, where CANH represents the high-level signal line and CANL represents the low-level signal line.

[0077] Both the master and slave units utilize three output lines: L1, L2, and N. The N line of the master and slave units is connected together, serving as the N line for the entire system. The dynamic phase line configuration unit dynamically configures the L1 and L2 lines of the master and slave units into phases A, B, and C, along with an auxiliary phase line (Aux), based on the load or grid type. Appropriate control methods are then implemented in the master and slave units to achieve various operating modes, including "single-phase three-wire and three-phase four-wire off-grid output modes," "single-phase three-wire output mode," "three-phase four-wire output mode," and "a mixed three-phase four-wire grid-connected and single-phase off-grid output mode."

[0078] For example, Figure 2 In the networking architecture shown, the dynamic phase line configuration unit can configure the L1 and L2 lines of the host as the A and B phase lines of the networking system respectively, and configure the L1 and L2 lines of the slave as the C and Aux phase lines of the networking system respectively.

[0079] It should be understood that in some embodiments of the present application, there may be other configuration methods, such as referring to Figure 4 , Figure 4 This is a schematic diagram of another parallel networking architecture of two single-phase three-wire inverters provided in an embodiment of the present application.

[0080] exist Figure 4 In the example, the master's L1 and L2 lines can be configured as the C and Aux phase lines of the network system, and the slave's L1 and L2 lines can be configured as the A and B phase lines of the network system. Other phase line dynamic configuration categories are not listed here.

[0081] In addition, it should be understood that the parallel networking solution provided by the present application is not limited to two single-phase three-wire inverters in parallel. In some other embodiments of the present application, it can also be extended to N (N≥3) single-phase three-wire inverters in parallel, where the host can be selected by the user or independently selected, and there is no restriction here.

[0082] The dynamic phase line configuration unit can obtain the A, B, C phase lines and the auxiliary phase line Aux by configuring the L1 and L2 lines of N inverters, and realize capacity expansion.

[0083] For example, refer to Figure 5 , Figure 5This is a schematic diagram of a parallel network architecture of N single-phase three-wire inverters provided in an embodiment of the present application.

[0084] exist Figure 5 In the example, the L1 and L2 lines of inverter #1 can be configured as the A and B phase lines of the network system, respectively; the L1 and L2 lines of inverter #2 can be configured as the C and Aux phase lines of the network system, respectively; and the L1 and L2 lines of inverter #N can be configured as the B and C phase lines of the network system, respectively. Other phase line dynamic configuration categories are not listed here.

[0085] It is understood that the common embodiment of the single-phase three-wire system described above has a 120 / 240V voltage output, and the common embodiment of the three-phase four-wire system has a 120 / 208V voltage output. In the embodiments of this application, the line-to-line single-phase output refers to the 240V output in the embodiments, and the line-to-neutral single-phase output refers to the 120V output in the embodiments. It should be understood that 120 / 208V and 120 / 240V are merely examples, and different output voltage combinations may be used depending on the specific conditions of the power system in each region.

[0086] It should be noted that the L1 and L2 phase lines of the single-phase inverter in the above embodiment are actually the grid-connected output phase lines of the grid-connected inverter, or the load phase lines of the off-grid inverter, or the grid-connected output phase lines and load phase lines of the grid-connected and off-grid inverters. This is only for abstract simplification.

[0087] In order to better understand the present application, the following embodiments take two single-phase three-wire inverters connected in parallel as an example to illustrate the phase line configuration method and control method of various working modes. The implementation method of various working modes of N single-phase three-wire inverters connected in parallel can be expanded accordingly and will not be repeated in the embodiments of the present application.

[0088] In some embodiments, the operating modes of the above networking system include:

[0089] The first mode: single-phase three-wire and three-phase four-wire off-grid output mode

[0090] When the user-connected load or grid type is a pure load, such as a three-phase load, and / or a line-to-line single-phase (corresponding to 240V voltage, etc.) load, and / or a line-to-neutral single-phase (corresponding to 120V voltage, etc.) load, the networking system operates in the first mode, namely the "single-phase three-wire and three-phase four-wire off-grid output mode".

[0091] In the first mode, the dynamic phase line configuration unit is used for at least one of the following:

[0092] Configuring the first phase line, the second phase line, and the third phase line as phase lines of the three-phase load;

[0093] Configuring the third phase line and the fourth phase line as phase lines of the line-to-line single-phase load;

[0094] The fourth phase line is configured as a phase line of the line-neutral single-phase load.

[0095] For example, Figure 6 As shown, Figure 6 This is a schematic diagram of a single-phase three-wire and three-phase four-wire off-grid output mode architecture provided in an embodiment of the present application.

[0096] In some embodiments, the L1 and L2 phase lines of the host "Inverter-M" are configured as a three-phase load Z 3P The A and B phase lines of the slave "Inverter-S" are configured as three-phase load Z 3P The C phase line realizes three-phase four-wire output.

[0097] The L2 phase line of the slave "Inverter-S" is configured as the Aux phase line, and is configured together with the L1 phase line of the slave to form a line-to-line single-phase load Z 2P The phase line and the N line are configured as a line-neutral single-phase load Z 1P phase line to achieve single-phase three-wire output.

[0098] In some embodiments, the first inverter is configured to: determine target voltage values ​​of the first phase line and the second phase line, control the output voltage between the first phase line, the second phase line, and the neutral line according to the target voltage values ​​of the first phase line and the second phase line; and send the target voltage value of the first phase line to the second inverter;

[0099] The above-mentioned second inverter is used to: determine the target voltage values ​​of the third phase line and the fourth phase line based on the target voltage value of the first phase line, and control the output voltage between the third phase line, the fourth phase line and the above-mentioned neutral line according to the target voltage values ​​of the third phase line and the fourth phase line.

[0100] In some implementations, the four phases A, B, C, and Aux can each be controlled as a single-phase output. By setting the phase relationship between the target voltage values ​​of the four phases A, B, C, and Aux, the required output voltage of each phase can be obtained. The specific control process is as follows:

[0101] After the user configures the phase line, the current working mode is set to "single-phase three-wire and three-phase four-wire off-grid output mode" on the host computer, and then the host computer indicates the current working mode to the host and slave through bus communication.

[0102] After receiving the instruction information indicating that the working mode is "first mode", the "DSP-M" of the host "Inverter-M" sets the target voltage value u of phase A A * The target voltage value u of phase B B* , where u B * by u A * The master sends the target voltage value u of phase A to the "DSP-S" of the "Inverter-S" of the slave through bus communication. A * , "DSP-S" respectively A * The target voltage value u of phase C is obtained by lagging 240° and 60° C * The target voltage value u of the Aux phase Aux * ,Then, the four phases A, B, C, and Aux respectively perform single-phase off-grid output voltage loop control.

[0103] Since the control loop of the off-grid output voltage of each phase only controls the difference between the target value and the sampled value, the control loop is described below using phase A as an example.

[0104] like Figure 7 As shown, Figure 7 This is a schematic diagram of an output voltage control loop provided in an embodiment of the present application.

[0105] In some embodiments, the target voltage value of phase A can be set to The orthogonal signal is constructed by shifting the phase by 90°, and then the d-axis voltage reference value u is obtained by αβ→dq transformation. A_d * and q-axis voltage reference value u A_q * Similarly, the A phase voltage u can be obtained A With the phase current i A The d-axis component u of the sampled value A_d 、i A_d and the q-axis component u A_q 、i A_q .

[0106] will u A_d * with u A_d Compare, u A_q * with u A_q After comparison, the d-axis current reference value i is obtained by the proportional integral (PI) controller. A_d * and the q-axis current reference value i A_q * , and then respectively with i A_d 、i A_qAfter comparison with the PI controller, the modulation signal d of phase A is obtained through dq→αβ inverse transformation. A After the pulse width modulation (PWM) generation module, the A phase switch tube S is obtained. A1 ~S A4 The control signal PWM A , thereby realizing the A-phase output voltage control.

[0107] The following describes in detail the phase relationship and output voltage relationship of the four phases A, B, C, and Aux in the first mode.

[0108] Reference Figure 8 , Figure 8 This is a phase diagram of a single-phase three-wire and three-phase four-wire off-grid output mode provided in an embodiment of the present application.

[0109] In some embodiments, the phase voltage u A As the benchmark, that is, u A =U m sinωt, then the phase voltage u B for u B =U m sin(ωt-120°), phase voltage u C for u C =U m sin(ωt+120°), phase voltage u Aux for u Aux =U m sin(ωt-60°). From this, we can get the line voltage relationship as:

[0110]

[0111] From the above analysis, we can know that controlling the voltage of each phase is as follows: Figure 8 After the display is shown, single-phase three-wire and three-phase four-wire off-grid output can be achieved.

[0112] It should be noted that in this mode, since phase C bears both three-phase load and line-to-line single-phase load, it may cause overload and midpoint potential balance issues. In some embodiments, this can be solved by conventional current limiting and auxiliary bridge arm midpoint potential balance.

[0113] Second mode: three-phase four-wire grid-connected and single-phase off-grid mixed output mode

[0114] When the user connects to the load or the grid type is grid and load: three-phase grid e A 、e B 、e C With line-neutral single-phase load Z 1PWhen the system is in the second mode, the networking system works in the second mode, namely the "three-phase four-wire grid-connected and single-phase off-grid mixed output mode".

[0115] In some embodiments, the dynamic phase line configuration unit is used for at least one of the following:

[0116] Configuring the first phase line, the second phase line, and the third phase line as phase lines of a power grid;

[0117] The fourth phase line is configured as a phase line of the line-neutral single-phase load.

[0118] For example, refer to Figure 9 , Figure 9 This is a schematic diagram of a three-phase four-wire grid-connected and single-phase off-grid hybrid output mode provided in an embodiment of the present application.

[0119] The L1 and L2 phase lines of the host "Inverter-M" are configured as the A and B phase lines of the three-phase grid (with the e A 、e B Phase connection), the L1 phase line of the slave "Inverter-S" is configured as the C phase line of the three-phase grid (connected to the e phase of the three-phase grid). C phase connection) to achieve three-phase four-wire grid-connected output.

[0120] The L2 phase line of the slave "Inverter-S" is configured as the Aux phase line, and together with the N line is configured as a line-neutral single-phase load Z 1P The phase line can realize line-neutral single-phase off-grid output.

[0121] In some embodiments, the first inverter is also used to: determine the phase sequence of the grid and the phase angle of the first phase line, determine the phase angle of the second phase line and the phase angle of the third phase line according to the positive or negative phase sequence, control the grid-connected current of the first phase line and the second phase line according to the phase angle of the first phase line and the second phase line, the sampled current of the first phase line and the second phase line, and the grid angular frequency; and send the phase angle of the third phase line and the grid angular frequency to the second inverter.

[0122] The second inverter is further used to: control the grid-connected current of the third phase line based on the phase angle of the third phase line, the sampled current of the third phase line, and the above-mentioned grid angular frequency obtained by the first inverter; determine the target voltage value of the fourth phase line based on the phase angle of the third phase line, and control the output voltage between the fourth phase line and the above-mentioned neutral line based on the target voltage value of the fourth phase line.

[0123] In some embodiments, the first inverter is a master inverter, and the second inverter is a slave inverter.

[0124] In the above embodiment, the master inverter calculates and determines the phase angle of the third phase line and directly sends it to the slave inverter, thereby reducing the amount of calculation of the slave inverter.

[0125] In some implementations, the A, B, and C phases can each be used for single-phase grid-connected current control, and the Aux phase can be used for single-phase off-grid voltage control. By setting the phase relationship between the four phases A, B, C, and Aux, the output voltage can be obtained. The specific control process is as follows:

[0126] First, after the user configures the phase line, the current working mode is set to the second mode on the host computer, and then the host computer publishes the current working mode to the host and slave through bus communication.

[0127] After receiving the indication information that the current working mode is the second mode, the "DSP-M" of the host "Inverter-M" starts to execute the single-phase phase-locked loop on phase A and phase B respectively to obtain the phase relationship between phase A and phase B, and then determine the three-phase phase sequence as the positive sequence "A→B→C" or the negative sequence "A→C→B", thereby determining the phase relationship of the four phases A, B, C, and D to achieve phase synchronization.

[0128] In some embodiments, phase A is continuously phase-locked to obtain a phase angle θ of phase A. A and grid angular frequency ω g , set the phase angle θ of phase B B =θ A -120°. The master sends the A phase angle θ to the slave "Inverter-S" "DSP-S" synchronously through bus communication. A and grid angular frequency ω g , “DSP-S” sets the phase angle θ of phase C C =θ A +120°, and set the target value of the Aux phase off-grid output voltage control loop Then the A, B, and C phases respectively perform single-phase grid-connected current loop control, and the Aux phase performs single-phase off-grid output voltage loop control.

[0129] The Aux phase control loop is the same as that in the aforementioned "single-phase three-wire and three-phase four-wire off-grid output modes" and is not described in detail here.

[0130] For the single-phase grid-connected current loop control of phases A, B, and C, only phase A needs to perform single-phase phase locking. The remaining phases only differ in phase angle and sampling value. Therefore, the control loop is described below using phase A as an example, and the remaining phases can be deduced analogously.

[0131] like Figure 10 As shown, Figure 10 This is another output voltage control loop schematic provided in an embodiment of the present application.

[0132] in, Figure 10 The three-phase sequence is shown as a positive sequence for illustration, and the negative sequence only needs to adjust the phase angle of each phase accordingly.

[0133] First, the A-phase grid voltage is passed through a single-phase phase-locked loop (PLL) to obtain the grid angular frequency ω g Phase angle θ with phase A A Then sample the A phase current i A , construct its orthogonal signal by shifting the phase by 90°, and then transform it through αβ→dq to obtain the d-axis component i of the A-phase current A_d and the q-axis component i A_q Similarly, the d-axis component e of the A-phase grid voltage can be obtained A_d and the q-axis component e A_q .

[0134] Then, i A_d and the d-axis current reference value i A_d * Compare, i A_q and the q-axis current reference value i A_q * After comparison, they are respectively passed through PI controllers and then superimposed with the grid feedforward component e A_d With e A_q After that, the same grid angular frequency ω g Phase angle θ with phase A A After being sent to the dq→αβ inverse transformation module, the modulation signal d of phase A is obtained. A After the PWM generation module, the A phase switch tube S is obtained. A1 ~S A4 The control signal PWM A , thereby realizing the A-phase grid-connected current control.

[0135] It should be noted that the above phase synchronization method obtains the phase angle of phase A and then synchronizes the phase angles of phases B and C via high-speed CAN communication. Phase synchronization here can also independently phase-lock phases A, B, and C. However, this may lead to control loop instability due to asynchronous sampling and accumulated phase errors. Therefore, in some implementations, corresponding sampling synchronization and phase compensation measures are required.

[0136] The third mode: three-phase four-wire off-grid and single-phase off-grid mixed output mode

[0137] When the user connects to the load or the grid type is grid and load, such as three-phase grid e A 、e B 、e C With three-phase load Z 3P and line-neutral single-phase load Z 1P When the system is in the third mode, the networking system works in the third mode, namely the "three-phase four-wire parallel off-grid and single-phase off-grid mixed output mode".

[0138] In some embodiments, the above-mentioned first inverter includes a first grid interface, a second grid interface, a first grid-connected switch, a second grid-connected switch, a first load interface, a second load interface, a first load switch and a second load switch; the first grid-connected switch is connected in series between the first phase line and the first grid interface, the second grid-connected switch is connected in series between the second phase line and the second grid interface, the first load switch is connected in series between the first phase line and the first load interface, and the second load switch is connected in series between the second phase line and the second load interface.

[0139] The above-mentioned second inverter includes a third grid interface, a fourth grid interface, a third grid-connected switch, a fourth grid-connected switch, a third load interface, a fourth load interface, a third load switch and a fourth load switch; the third grid-connected switch is connected in series between the third phase line and the third grid interface, the fourth grid-connected switch is connected in series between the fourth phase line and the fourth grid interface, the third load switch is connected in series between the third phase line and the third load interface, and the fourth load switch is connected in series between the fourth phase line and the fourth load interface.

[0140] In some embodiments, the dynamic phase line configuration unit is used for at least one of the following:

[0141] Connecting any three of the first grid interface, the second grid interface, the third grid interface, and the fourth grid interface to a phase line of the grid;

[0142] Connecting the first load interface, the second load interface, and the third load interface to the phase lines of the three-phase load;

[0143] Connect the fourth load interface to the phase line of the above line-neutral single-phase load.

[0144] In some embodiments, the third mode includes a grid-connected mode and an off-grid mode.

[0145] In the grid-connected mode, the first grid-connected switch, the second grid-connected switch, the third grid-connected switch, the fourth grid-connected switch, the first load switch, the second load switch, the third load switch, and the fourth load switch are all in a closed state.

[0146] In the off-grid mode, the first grid-connected switch, the second grid-connected switch, the third grid-connected switch and the fourth grid-connected switch are all in the open state; the first load switch, the second load switch, the third load switch and the fourth load switch are all in the closed state.

[0147] For example, refer to Figure 11 , Figure 11 This is a schematic diagram of a three-phase four-wire parallel-off-grid and single-phase off-grid mixed output mode provided in an embodiment of the present application.

[0148] In some embodiments, the master inverter-M and the slave inverter-S are equipped with grid interfaces G-L1 and G-L2 (the first and second grid interfaces) and load interfaces Backup-L1 and Backup-L2 (the first and second load interfaces). The master's G-L1 and G-L2 phase lines are configured as the GA and GB phase lines of the grid, and the slave inverter-S's G-L1 (the third grid interface) is configured as the GC phase line of the grid, achieving three-phase four-wire grid-connected output.

[0149] The master's Backup-L1 and Backup-L2 are configured as the Backup-A and Backup-B phase lines of the three-phase load, and the slave's Backup-L1 (the third load interface mentioned above) is configured as the Backup-C phase line of the three-phase load, realizing three-phase four-wire off-grid output.

[0150] The slave's Backup-L2 (the fourth load interface) is configured as the Backup-Aux phase line and together with the N line is configured as a line-neutral single-phase load Z 1P The phase line can realize line-neutral off-grid output.

[0151] The master and slave devices switch between on-grid and off-grid modes through the grid-connected switch. The control process is as follows:

[0152] First, after the user configures the phase line, the current working mode is set to the third mode on the host computer, and then the host computer publishes the current working mode to the host and slave through bus communication.

[0153] After receiving the indication information that the current working mode is the third mode, the DSP-M of the host "Inverter-M" first detects the voltage of the grid interfaces G-L1 and G-L2, determines the current grid status, and thus enters the grid-connected mode or off-grid mode.

[0154] In the grid-connected mode, all the above-mentioned grid-connected switches and load switches are closed, and the three-phase GA, GB, and GC perform grid-connected current control. The grid and inverter jointly supply power to the load. The control method is the same as the control method of the three-phase A, B, and C in the "three-phase four-wire grid-connected and single-phase off-grid mixed output mode" and is not repeated here.

[0155] In off-grid mode, the above-mentioned grid-connected switches are disconnected, the above-mentioned load switches are closed, and the three-phase Backup-A, Backup-B, and Backup-C perform off-grid output voltage control. The control method of the three-phase A, B, and C in the "single-phase three-wire and three-phase four-wire off-grid output modes" is the same and will not be repeated here.

[0156] In both grid-connected and off-grid modes, the Backup-Aux phase performs off-grid output voltage control to ensure continuous power supply to the line-neutral single-phase load. The control method is the same as the Aux phase control method in the "three-phase four-wire grid-connected and single-phase off-grid mixed output mode" and is not repeated here.

[0157] It should be noted that in the embodiment of the present application, the phase line is dynamically configured, so it is compatible with conventional parallel modes, such as a single-phase three-wire parallel output mode, in which the phase line is configured as a conventional wiring method and the control method is controlled according to the conventional method, which will not be described in detail.

[0158] The single-phase, three-wire inverter parallel networking solution proposed in this application embodiment can simultaneously achieve three user-required voltage outputs, adapting to a wider range of user scenarios. Furthermore, by connecting the N lines of the parallel inverters and configuring the phase line configuration based on user needs through a dynamic phase line configuration unit, wiring becomes more flexible and convenient.

[0159] In the description of the embodiments of this application, it should be noted that, unless otherwise expressly specified or limited, the term "connection" should be understood in a broad sense. For example, it can refer to a fixed connection, an indirect connection via an intermediate medium, internal communication between two components, or an interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of this application based on specific circumstances.

[0160] The above specific implementation methods further illustrate the purpose, technical solutions and beneficial effects of this application in detail. It should be understood that the above are only specific implementation methods of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent replacements, improvements, etc. made on the basis of the technical solutions of this application should be included in the scope of protection of this application.

[0161] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present application, rather than to limit them. Although the embodiments of the present application have been described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the above embodiments, or replace some or all of the technical features therein with equivalents. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A networking system based on an inverter, characterized in that: The networking system includes: a first inverter, a second inverter, a dynamic phase line configuration unit, a load and / or a power grid, wherein the load includes at least one of a three-phase load, a line-to-line single-phase load, and a line-to-neutral single-phase load; The first inverter includes a first phase line, a second phase line and a first neutral line, and the second inverter includes a third phase line, a fourth phase line and a second neutral line; The dynamic phase line configuration unit is configured to configure at least one of the first phase line, the second phase line, the third phase line, and the fourth phase line as a phase line of the load and / or the power grid; and to connect the first neutral line and the second neutral line to configure them as the neutral line of the load and / or the power grid; The first inverter is used to control the output voltage between the first phase line, the second phase line and the neutral line, or control the grid-connected current of the first phase line and / or the second phase line, according to the working mode of the networking system; the second inverter is used to control the output voltage between the third phase line, the fourth phase line and the neutral line, or control the grid-connected current of the third phase line and / or the fourth phase line, according to the working mode.

2. The system according to claim 1, wherein: The working mode of the networking system includes a first mode; the dynamic phase line configuration unit is used for at least one of the following: configuring the first phase line, the second phase line, and the third phase line as phase lines of the three-phase load; Configuring the third phase line and the fourth phase line as phase lines of the line-to-line single-phase load; The fourth phase line is configured as a phase line of the line-neutral single-phase load.

3. The system according to claim 2, characterized in that The first inverter is configured to: determine target voltage values ​​of the first phase line and the second phase line, control the output voltage between the first phase line, the second phase line, and the neutral line according to the target voltage values ​​of the first phase line and the second phase line; and send the target voltage value of the first phase line to the second inverter; The second inverter is used to: determine the target voltage values ​​of the third phase line and the fourth phase line based on the target voltage value of the first phase line, and control the output voltage between the third phase line, the fourth phase line and the neutral line according to the target voltage values ​​of the third phase line and the fourth phase line.

4. The system according to claim 1, wherein: The working mode of the networking system includes the second mode; the dynamic phase line configuration unit is used for at least one of the following: configuring the first phase line, the second phase line, and the third phase line as phase lines of the power grid; The fourth phase line is configured as a phase line of the line-neutral single-phase load.

5. The system according to claim 4, characterized in that The first inverter is further configured to: determine a grid phase sequence and a phase angle of the first phase line, determine a phase angle of the second phase line and a phase angle of the third phase line according to a positive or negative phase sequence, control a grid-connected current of the first phase line and the second phase line according to the phase angle of the first phase line and the second phase line, the sampled current of the first phase line and the second phase line, and a grid angular frequency; and send the phase angle of the third phase line and the grid angular frequency to the second inverter; The second inverter is further configured to: control the grid-connected current of the third phase line according to the phase angle of the third phase line, the sampled current of the third phase line, and the grid angular frequency obtained by the first inverter; A target voltage value of the fourth phase line is determined according to the phase angle of the third phase line, and an output voltage between the fourth phase line and the neutral line is controlled according to the target voltage value of the fourth phase line.

6. The system according to claim 5, characterized in that The first inverter is a master inverter, and the second inverter is a slave inverter.

7. The system according to claim 1, wherein: The first inverter includes a first grid interface, a second grid interface, a first grid-connected switch, a second grid-connected switch, a first load interface, a second load interface, a first load switch, and a second load switch; the first grid-connected switch is connected in series between the first phase line and the first grid interface, the second grid-connected switch is connected in series between the second phase line and the second grid interface, the first load switch is connected in series between the first phase line and the first load interface, and the second load switch is connected in series between the second phase line and the second load interface; The second inverter includes a third grid interface, a fourth grid interface, a third grid-connected switch, a fourth grid-connected switch, a third load interface, a fourth load interface, a third load switch, and a fourth load switch; the third grid-connected switch is connected in series between the third phase line and the third grid interface, the fourth grid-connected switch is connected in series between the fourth phase line and the fourth grid interface, the third load switch is connected in series between the third phase line and the third load interface, and the fourth load switch is connected in series between the fourth phase line and the fourth load interface.

8. The system according to claim 7, characterized in that The working mode of the networking system includes a third mode; the dynamic phase line configuration unit is used for at least one of the following: connecting any three of the first grid interface, the second grid interface, the third grid interface, and the fourth grid interface to a phase line of the grid; Connecting the first load interface, the second load interface, and the third load interface to phase lines of the three-phase load; The fourth load interface is connected to a phase line of the line-neutral single-phase load.

9. The system according to claim 8, characterized in that The third mode includes a grid-connected mode and an off-grid mode; In the grid-connected mode, the first grid-connected switch, the second grid-connected switch, the third grid-connected switch, the fourth grid-connected switch, the first load switch, the second load switch, the third load switch, and the fourth load switch are all in a closed state; In the off-grid mode, the first grid-connected switch, the second grid-connected switch, the third grid-connected switch, and the fourth grid-connected switch are all in an off state; The first load switch, the second load switch, the third load switch, and the fourth load switch are all in a closed state.

10. The system according to any one of claims 1 to 9, characterized in that The networking system also includes a host computer; The host computer is communicatively connected with the first inverter and the second inverter; The host computer is used to send instruction information to the first inverter and the second inverter, and the instruction information is used to indicate the working mode of the networking system.

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