Inverter-based networking system

Abstract

The application 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, 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 the load and / or the power grid, and connecting the first neutral line and the second neutral line to configure a neutral line of the load and / or the power grid, the first inverter is used for controlling the output voltage between the first phase line, the second phase line and the neutral line according to the working mode, or controlling the grid-connected current of the first phase line and / or the second phase line, and the second inverter is used for controlling the output voltage between 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 above-mentioned networking system can adapt to various user scene requirements.

Description

Technical Field

[0001] This application relates to the field of power electronic conversion technology, and in particular to a network system based on an inverter. Background Technology

[0002] In some regions, household user loads mainly consist of single-phase devices (such as 120V single-phase devices and 240V single-phase devices), so user energy storage deployments are usually single-phase three-wire inverters.

[0003] However, some households may have three-phase loads (such as 208V three-phase equipment), which requires users to deploy an additional three-phase inverter, resulting in higher costs. Summary of the Invention

[0004] This application provides a network system based on an inverter, which can adapt to various user scenarios and reduce the cost of use for home users.

[0005] In some embodiments of this application, the inverter-based networking system includes: a first inverter, a second inverter, a dynamic phase 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-neutral single-phase load.

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

[0007] The dynamic phase configuration unit is used 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 configure the first neutral line as the neutral line of the load and / or the power grid after connecting the first neutral line and the second neutral line.

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

[0009] In one possible implementation, the operating mode of the above-described networking system includes a first mode; the dynamic phase line configuration unit is used for at least one of the following:

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

[0011] Configure the aforementioned third and fourth phase lines as phase lines for a single-phase load between lines;

[0012] Configure the aforementioned fourth phase line as a phase line of a line-neutral single-phase load.

[0013] In one possible implementation, the first inverter is used to: determine the 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 and fourth phase lines based on the target voltage value of the first phase line, and control the output voltage between the third and fourth phase lines and the neutral line according to the target voltage values ​​of the third and fourth phase lines.

[0015] In one possible implementation, the network system operates in a second mode; the dynamic phase configuration unit is used for at least one of the following:

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

[0017] Configure the aforementioned fourth phase line as a phase line of a line-neutral single-phase load.

[0018] In one possible implementation, the first inverter is further configured to: determine the grid phase sequence 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 aforementioned grid angular frequency to the second inverter.

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

[0020] In one possible implementation, the first inverter is the master inverter, and the second inverter is the 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 network system operates in a third mode; the dynamic phase configuration unit is used for at least one of the following:

[0024] Connect any three of the above-mentioned first power grid interface, second power grid interface, third power grid interface and fourth power grid interface to the phase line of the power grid;

[0025] Connect 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 the line-neutral single-phase load.

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

[0028] In 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 the closed state;

[0029] In 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 this application embodiment can configure different phase lines according to different loads of household users or grid scenarios, and realize multiple voltage outputs, including two single-phase voltage levels and one three-phase voltage level output simultaneously, which can meet the diverse load needs of household users and reduce the usage costs of household users. Attached Figure Description

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

[0032] Figure 1 This is a schematic diagram of a typical topology of a single-phase three-wire inverter provided in the embodiments of this application;

[0033] Figure 2 This is a schematic diagram of the architecture of a network system based on an inverter provided in the embodiments of this application;

[0034] Figure 3 This is a schematic diagram of a parallel network architecture for two single-phase three-wire inverters provided in an embodiment of this application;

[0035] Figure 4 This is a schematic diagram of another parallel networking architecture of two single-phase three-wire inverters provided in the embodiments of this application;

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

[0037] 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 the embodiments of this application;

[0038] Figure 7 This is a schematic diagram of an output voltage control loop provided in an embodiment of this application;

[0039] Figure 8 This application provides a phase diagram of a single-phase three-wire and a three-phase four-wire off-grid output mode.

[0040] Figure 9 This is a schematic diagram of a mixed output mode of three-phase four-wire grid-connected and single-phase off-grid provided in the embodiments of this application;

[0041] Figure 10 This is a schematic diagram of another output voltage control loop provided in the embodiments of this application;

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

[0043] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0044] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0045] To facilitate a clear description of the technical solutions in the embodiments of this application, terms such as "exemplary" and "for example" are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design scheme described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0046] In this application embodiment, "at least one" refers to one or more, and "more than one" refers to two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single 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 relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have 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 switching control of semiconductor switching devices. It is now widely used in new energy power generation, electric vehicles, industrial drives, and home appliances.

[0048] An inverter can convert DC to AC through the following steps:

[0049] S1. Rectification and Filtering (Some Scenarios): If the input is AC power (such as mains power), it needs to be converted to DC power by a rectifier first, 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 controls the switching devices to turn on and off, and chops the DC voltage into a high-frequency pulse sequence.

[0051] S3. Filtering and Voltage Regulation: After the pulse sequence is smoothed by an LC filter, a sinusoidal AC output is generated. By adjusting the duty cycle through pulse-width modulation (PWM) technology, the output voltage amplitude and frequency can be precisely controlled.

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

[0053] In some regions, household loads mainly consist of single-phase devices (such as 120V single-phase devices and 240V single-phase devices), so user energy storage deployments are typically 120 / 240V single-phase three-wire inverters.

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

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

[0056] In addition, the aforementioned single-phase three-wire inverter also includes:

[0057] N-line: also known as the neutral line, is drawn from the center tap of the inverter output filter circuit. It provides a potential reference point for the entire circuit and is usually close to the ground potential (equipotential with the ground in a grounding system).

[0058] L1 and L2 lines: These two lines are live lines. They carry the AC power after inversion and filtering, and have the same voltage amplitude relative to the neutral (N) line, but their phase relationship depends on the specific design and operating mode of the inverter. In some applications, the voltage output by L1 and L2 is equal in magnitude but opposite in phase to the N line; in other applications, they can output different voltage levels to meet different load requirements.

[0059] However, some users may have three-phase loads (such as 208V), and deploying an additional three-phase inverter would be costly. Therefore, how to obtain three-phase power from existing 120 / 240V single-phase three-wire inverters is a pressing technical problem that needs to be solved.

[0060] To address the aforementioned technical challenges, this application provides an inverter-based networking system, specifically a parallel networking system based on a single-phase three-wire inverter. This system allows for different phase configurations based on varying user loads or grid scenarios, coupled with appropriate control methods, to achieve the voltage output required by the user. This includes simultaneous output of up to two single-phase voltage levels and one three-phase voltage level, satisfying diverse user load needs. For example, through dynamic phase configuration and corresponding control algorithms, it is possible to simultaneously output 120V single-phase, 240V single-phase, and 208V three-phase power, thus simultaneously obtaining 120 / 240V single-phase three-wire power and 120 / 208V three-phase power, thereby meeting the diverse load application needs of residential users.

[0061] In terms of control, a half-bridge inverter control method can be adopted. By adjusting the target value of the control voltage 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 in this application will be 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 described again in different embodiments.

[0063] For example, refer to Figure 2 , Figure 2 This is a schematic diagram of the architecture of a network system based on an inverter provided in the embodiments of this application.

[0064] In some embodiments, the above-mentioned networking system includes: a first inverter 201, a second inverter 202, a dynamic phase 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 aforementioned first inverter 201 includes a first phase line and a second phase line (i.e., Figure 2 The second inverter 202 includes a third phase line and a fourth phase line (i.e., phase lines L1 and L2 connected to the first inverter 201). Figure 2 Phase lines L1 and L2 connected to the second inverter 202.

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

[0067] For example, the dynamic phase line configuration unit 203 can configure the first phase line, the second phase line, and the third phase line as phase line A, phase line B, and phase line 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 (i.e., Figure 2 The second inverter 202 includes a second neutral line (i.e., the N line connected to the first inverter 201). Figure 2 (The 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 to the neutral line of the second inverter 202, and then configure it as the neutral line N of the load and / or the power 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 to control the output voltage between the second phase line and the neutral line N, according to the working mode of the grid 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 to control the output voltage between the fourth phase line and the neutral line N, according to the above operating mode; or to 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 can be used to send instruction information to the first inverter and the second inverter, which is used to indicate the operating mode of the network system.

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

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

[0076] In some implementations, the host computer is connected to "Inverter-M" and "Inverter-S" via a bus (such as CANH and CANL). CANH and CANL are two physical signal lines on the Controller Area Network (CAN) bus, with CANH representing the high-level signal line and CANL representing the low-level signal line.

[0077] Both the master and slave units have three-wire outputs (L1, L2, N), with their N-wires connected to form the N-wire of the entire system. Through a dynamic phase configuration unit, the L1 and L2 wires of the master and slave units are dynamically configured as phases A, B, and C, and the auxiliary phase Aux, based on the load or grid type. Corresponding control methods are then applied in both the master and slave units to achieve various operating modes, such as "single-phase three-wire and three-phase four-wire off-grid output mode," "single-phase three-wire output mode," "three-phase four-wire output mode," and "three-phase four-wire grid-connected and single-phase off-grid mixed output mode."

[0078] For example, Figure 2 In the network 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 network system, respectively, and configure the L1 and L2 lines of the slave as the C and Aux phase lines of the network system, respectively.

[0079] It should be understood that other configuration methods may exist in some embodiments of this application, such as those described above. Figure 4 , Figure 4 This is a schematic diagram of another parallel networking architecture of two single-phase three-wire inverters provided in the embodiments of this application.

[0080] exist Figure 4 In this configuration, the L1 and L2 lines of the host can be configured as the C and Aux phase lines of the network system, respectively, and the L1 and L2 lines of the slave can be configured as the A and B phase lines of the network system, respectively. Other dynamic configuration categories for phase lines are not listed here.

[0081] Furthermore, it should be understood that the parallel networking scheme provided in this application is not limited to two single-phase three-wire inverters connected in parallel. In some other embodiments of this application, it can be extended to N (N≥3) single-phase three-wire inverters connected in parallel, wherein the host can be selected by the user or by the user himself, 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 for N single-phase three-wire inverters provided in the embodiments of this application.

[0084] exist Figure 5 In this configuration, 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 so on. The L1 and L2 lines of inverter #N can be configured as the B and C phase lines of the network system, respectively. Other dynamic configuration categories for phase lines are not listed here.

[0085] It is understood that the common implementation of the above-mentioned single-phase three-wire system is a 120 / 240V voltage output, and the common implementation of the three-phase four-wire system is a 120 / 208V voltage output. In the embodiments of this application, the single-phase output between lines refers to the 240V output in the embodiment, and the single-phase output of the line neutral refers to the 120V output in the embodiment. It should be understood that 120 / 208V and 120 / 240V are only one embodiment, and in reality, different combinations of output voltages may exist depending on the power system conditions in different regions.

[0086] It should be noted that the L1 and L2 phase lines of the single-phase inverter in the above embodiments 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 parallel-off-grid inverter. This is only an abstract simplification.

[0087] To better understand this application, the following embodiments use two single-phase three-wire inverters connected in parallel as an example to illustrate the phase line configuration and control methods for various operating modes. The implementation methods for various operating modes of N single-phase three-wire inverters connected in parallel can be extended accordingly, and will not be elaborated in the embodiments of this application.

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

[0089] First mode: Off-grid output mode for single-phase three-wire and three-phase four-wire

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

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

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

[0093] Configure the aforementioned third and fourth phase lines as phase lines for the aforementioned single-phase load between lines;

[0094] Configure the aforementioned fourth phase line as the phase line of the aforementioned line-neutral single-phase load.

[0095] For example, such as 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 the embodiments of this application.

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

[0097] The L2 phase line of the slave inverter-S is configured with the Aux phase line, which, together with the L1 phase line of the slave, is configured as an inter-line single-phase load Z. 2P The phase line, and the Z line configured together with the N line as a line-neutral single-phase load. 1P The phase line enables single-phase three-wire output.

[0098] In some embodiments, the first inverter is configured to: determine the 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 based on 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 second inverter described above is used to: determine the target voltage values ​​of the third and fourth phase lines based on the target voltage value of the first phase line, and control the output voltage between the third and fourth phase lines and the neutral line according to the target voltage values ​​of the third and fourth phase lines.

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

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

[0102] After receiving the indication that the operating mode is "Mode 1", the "DSP-M" of the main unit "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 voltage is obtained with a 120° lag. The host synchronously sends the target voltage value u of phase A to the "DSP-S" of the slave "Inverter-S" via bus communication. A * "DSP-S" will respectively u A * The target voltage value u of phase C is obtained by lags of 240° and 60°. C * The target voltage value u of the Aux phase Aux * Then, phases A, B, C, and Aux each execute single-phase off-grid output voltage loop control.

[0103] Since the control loops for the off-grid output voltage of each phase only control the target value and the sampled value, the control loop will be explained 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 this application.

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

[0106] will u A_d * with u A_d Comparison, u A_q * with u A_q After comparison, the d-axis current reference value i is obtained through a proportional-integral (PI) controller. A_d * With q-axis current reference value i A_q * Then, respectively with i A_d i A_qAfter comparison with the PI controller, the modulation signal d of phase A is obtained through the inverse dq→αβ transform. A After passing through the Pulse Width Modulation (PWM) generation module, the A-phase switch S is obtained. A1 ~S A4 PWM control signal A This enables the control of the output voltage of phase A.

[0107] The following is a detailed explanation of 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 a three-phase four-wire off-grid output mode provided in the embodiments of this application.

[0109] In some implementations, the phase voltage u can be used. A As a reference, i.e., 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°). Therefore, the line voltage relationship can be obtained as:

[0110]

[0111] As can be seen from the above analysis, controlling the voltage of each phase as follows: Figure 8 As shown, this enables single-phase three-wire and three-phase four-wire off-grid output.

[0112] It should be noted that in this mode, since C simultaneously bears both three-phase load and single-phase inter-line load, overload and neutral point potential imbalance issues may arise. In some implementations, this can be resolved through conventional current limiting and auxiliary arm balancing of the neutral point potential.

[0113] Second mode: Mixed output mode of three-phase four-wire grid connection and single-phase off-grid.

[0114] When the user connects to the load or the power grid type is power grid and load: three-phase power grid e A e B e C With line-neutral single-phase load Z 1PAt this time, the network system operates in the second mode, namely the "mixed output mode of three-phase four-wire grid connection and single-phase off-grid".

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

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

[0117] Configure the aforementioned fourth phase line as the phase line of the aforementioned line-neutral single-phase load.

[0118] For example, refer to Figure 9 , Figure 9 This is a schematic diagram of a mixed output mode of three-phase four-wire grid connection and single-phase off-grid provided in the embodiments of this application.

[0119] The L1 and L2 phase lines of the main unit "Inverter-M" are configured as the A and B phase lines of the three-phase power grid (connected to the e-phase of the three-phase power grid). A e B (Connected), the L1 phase line of the slave unit "inverter-S" is configured as the C phase line of the three-phase power grid (connected to the e phase of the three-phase power grid). C (Connected in phase) 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, it is configured as a line-neutral single-phase load Z. 1P The phase line enables line-neutral single-phase off-grid output.

[0121] In some embodiments, the first inverter is further configured to: determine the grid phase sequence 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 also used to: control the grid-connected current of the third phase line based on the phase angle of the third phase line obtained by the first inverter, the sampled current of the third phase line, and the grid angular frequency; 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 neutral line based on the target voltage value of the fourth phase line.

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

[0124] In the above implementation, the phase angle of the third phase line is calculated by the master inverter and sent directly to the slave inverter, thereby reducing the computational load of the slave inverter.

[0125] In some implementations, phases A, B, and C can be used for single-phase grid-connected current control, and phase Aux 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 host computer sets the current working mode to the second mode. Then, the host computer publishes the current working mode to the host and slave devices through bus communication.

[0127] After receiving the indication that the current operating mode is the second mode, the DSP-M of the main unit "Inverter-M" starts to execute single-phase phase-locked loops for phase A and phase B respectively to obtain the phase relationship between phase A and phase B, and then determines whether the three-phase sequence is positive sequence "A→B→C" or negative sequence "A→C→B", thereby determining the phase relationship of the four phases A, B, C, and D and achieving phase synchronization.

[0128] In some implementations, phase-locking is continuously performed on phase A to obtain the phase angle θ of phase A. A With the angular frequency ω of the power grid g Set the phase angle θ of phase B. B =θ A -120°. The master unit synchronously sends the A-phase phase angle θ to the slave unit "DSP-S" of "Inverter-S" via bus communication. A With the angular frequency ω of the power grid g "DSP-S" sets the C-phase phase angle θ C =θ A +120°, and set the target value for the Aux phase off-grid output voltage control loop. Then, phases A, B, and C respectively execute single-phase grid-connected current loop control, while phase Aux executes 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 will not be repeated here.

[0130] In the single-phase grid-connected current loop control of the three phases A, B, and C, only phase A needs to perform single-phase phase locking. The others are only different in phase angle and sampling value. Therefore, the control loop is explained below using phase A as an example. The other phases can be deduced by analogy.

[0131] like Figure 10 As shown, Figure 10 This is a schematic diagram of another output voltage control loop provided in the embodiments of this application.

[0132] in, Figure 10 The above three-phase sequence is used as an example for illustration. For negative sequence, only the phase angle of each phase needs to be adjusted accordingly.

[0133] First, the A-phase grid voltage is passed through a single-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 By constructing an orthogonal signal through a 90° phase shift, and then performing an αβ→dq transformation, the d-axis component i of the A-phase current is obtained. A_d With q-axis component i A_q Similarly, the d-axis component e of the A-phase grid voltage can be obtained. A_d With q-axis component e A_q .

[0134] Then, i A_d With d-axis current reference value i A_d * Comparison, i A_q With q-axis current reference value i A_q * After comparison, the results are passed through a PI controller and then superimposed with the grid feedforward component e. A_d With e A_q Then, the same as the grid angular frequency ω g Phase angle θ with phase A A After being fed into the dq→αβ inverse transform module, the modulation signal d of phase A is obtained. A After passing through the PWM generation module, the A-phase switch S is obtained. A1 ~S A4 PWM control signal A This enables grid-connected current control of phase A.

[0135] It should be noted that the phase synchronization method described above, after obtaining the phase angle of phase A, uses high-speed CAN communication to synchronously obtain the phase angles of phases B and C. Phase synchronization can also be achieved by independently phase-locking phases A, B, and C, but this may lead to control loop instability due to asynchronous sampling and accumulated phase errors. Therefore, in some implementations, appropriate sampling synchronization and phase compensation measures are required.

[0136] Third mode: Mixed output mode of three-phase four-wire parallel-off-grid and single-phase off-grid.

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

[0138] In some embodiments, 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.

[0139] The aforementioned 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 described above is used for at least one of the following:

[0141] Connect any three of the following grid interfaces—the first grid interface, the second grid interface, the third grid interface, and the fourth grid interface—to the phase lines of the power grid;

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

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

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

[0145] In 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 the closed state.

[0146] In 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 mixed output mode of three-phase four-wire parallel-off-grid and single-phase off-grid provided in the embodiments of this application.

[0148] In some implementations, the master inverter "M" and the slave inverter "S" each have grid interfaces G-L1 and G-L2 (the aforementioned first grid interface and second grid interface) and load interfaces Backup-L1 and Backup-L2 (the aforementioned first load interface and second load interface), respectively. The G-L1 and G-L2 phase lines of the master inverter are configured as the GA and GB phase lines of the power grid, and the G-L1 (the aforementioned third grid interface) of the slave inverter "S" is configured as the GC phase line of the power grid, realizing three-phase four-wire grid-connected output.

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

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

[0151] The master and slave units switch between grid-connected and off-grid modes via a grid-connection 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. Then, the host computer publishes the current working mode to the host and slave devices through bus communication.

[0153] After receiving the indication that the current working mode is the third mode, the "DSP-M" of the main unit "Inverter-M" first detects the voltage of the grid interface G-L1 and G-L2 to determine the current grid status, and then enters the grid-connected mode or the off-grid mode.

[0154] In grid-connected mode, all grid-connected switches and load switches are closed. GA, GB, and GC three-phase grid-connected current control is implemented, and the power grid and inverter jointly supply power to the load. The control method is the same as the A, B, and C three-phase control method in the "three-phase four-wire grid-connected and single-phase off-grid hybrid output mode", which will not be elaborated here.

[0155] In off-grid mode, all the above-mentioned grid-connected switches are disconnected, and all the above-mentioned load switches are closed. Backup-A, Backup-B, and Backup-C three-phases perform off-grid output voltage control, which is the same as the A, B, and C three-phase control method in the "single-phase three-wire and three-phase four-wire off-grid output modes", and will not be described in detail 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. Its control method is the same as that of the Aux phase in the "three-phase four-wire grid-connected and single-phase off-grid mixed output mode", and will not be described in detail here.

[0157] It should be noted that in the embodiments of this application, the phase wires are dynamically configured, so they are compatible with conventional parallel modes, such as single-phase three-wire parallel output mode, where the phase wires are configured using conventional wiring methods and the control method is controlled using conventional methods, without further details.

[0158] The parallel networking scheme for single-phase three-wire inverters proposed in this application can simultaneously achieve three different user-demand voltage outputs, adapting to a wider range of user scenarios. Furthermore, by connecting the neutral (N) lines of the parallel inverters and configuring the phase lines according to 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 explicitly specified and limited, the term "connection" should be interpreted broadly. For example, it can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal connection of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0160] The above specific embodiments further illustrate the purpose, technical solution and beneficial effects of this application. It should be understood that the above are only specific embodiments of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made on the basis of the technical solution of this application should be included within 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 this application, and are not intended to limit them; although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An inverter-based networking system, comprising: The network system includes: a first inverter, a second inverter, a dynamic phase-line configuration unit, loads and / or the power grid, wherein the loads include at least one of three-phase loads, line-to-line single-phase loads, and line-neutral single-phase loads; The first inverter includes a first phase line, a second phase line, and a first neutral line; the second inverter includes a third phase line, a fourth phase line, and a second neutral line. The dynamic phase line configuration unit is used 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 configure the first neutral line as the neutral line of the load and / or the power grid after connecting the first neutral line and the second neutral line. The dynamic phase line configuration unit configures the fourth phase line as an auxiliary phase line to achieve simultaneous output of single-phase and three-phase voltages. The first inverter is used to control the output voltage between the first phase line, the second phase line and the neutral line, or to control the grid-connected current of the first phase line and / or the second phase line, according to the operating mode of the network 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 to control the grid-connected current of the third phase line and / or the fourth phase line, according to the operating mode.

2. The system according to claim 1, characterized in that, The network system operates in a first mode; the dynamic phase line configuration unit is used for at least one of the following: Configure the first phase line, the second phase line, and the third phase line as the phase lines of the three-phase load; Configure the third phase line and the fourth phase line as the phase lines of the inter-line single-phase load; The fourth phase line is configured as the 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 the 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, characterized in that, The network system operates in a second mode; the dynamic phase line configuration unit is used for at least one of the following: The first phase line, the second phase line, and the third phase line are configured as phase lines of the power grid; The fourth phase line is configured as the 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 the grid phase sequence 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. The second inverter is further configured to: control the grid-connected current of the third phase line based on the phase angle of the third phase line obtained by the first inverter, the sampled current of the third phase line, and the grid angular frequency; Based on the phase angle of the third phase line, the target voltage value of the fourth phase line is determined, and based on the target voltage value of the fourth phase line, the output voltage between the fourth phase line and the neutral line is controlled.

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

7. The system according to claim 1, characterized in that, 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 network system operates in a third mode; the dynamic phase line configuration unit is used for at least one of the following: Connect any three of the following power grid interfaces—the first, second, third, and fourth—to the phase lines of the power grid. Connect the first load interface, the second load interface, and the third load interface to the phase lines of the three-phase load; Connect the fourth load interface to the phase line of the line-neutral single-phase load.

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

Images