Inverter and PLC system

Abstract

The present application relates to the technical field of photovoltaics, and provides an inverter and a PLC system. In the inverter provided by the present application, a power conversion circuit is configured to be connected to a power line, and a PLC circuit is coupled to a first transmission line and a second transmission line in the power line by means of a first transformer and a second transformer. The PLC circuit is coupled to the two transmission lines in the power line by means of the two transformers, so that common mode noise in the power line can be effectively suppressed. In addition, the PLC circuit is coupled to the power line in an electromagnetic induction manner by means of the two transformers, so that noise generated by the power conversion circuit can be effectively suppressed. Therefore, the inverter provided in the present application can ensure that a PLC signal in the PLC circuit has a high signal-to-noise ratio both when coupled to the power line and when coupled from the power line.

Description

Inverter and PLC system

[0001] The present application claims priority to the Chinese patent application No. 202420809118.8, filed on April 17, 2024, and entitled "Inverter and PLC system", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of photovoltaic technology, and in particular, to an inverter and a PLC system. BACKGROUND

[0003] A photovoltaic (PV) power generation system generally includes photovoltaic panels, photovoltaic optimizers, and inverters, etc. Among them, the inverter is used to convert the direct current (DC) output by the photovoltaic panel into alternating current (AC). The photovoltaic optimizer is used to perform maximum power point tracking (MPPT) on the photovoltaic panel to ensure that the output power of the photovoltaic panel is maximum. Generally, one photovoltaic optimizer can be connected to each photovoltaic panel to achieve power optimization at the component level. Moreover, the inverter and the photovoltaic optimizer can communicate through power line communication (PLC) technology to realize information interaction operations such as business query and command control.

[0004] The inverter generally includes a power conversion circuit, a monitoring circuit, and a communication circuit. The communication circuit can adopt PLC technology, and the communication circuit can include a modem circuit, a PLC circuit, and a coupler, etc. Among them, the modem circuit is used to realize modulation and demodulation of the PLC signal, the PLC circuit is coupled to the power line through the coupler, and is used to interact with the photovoltaic optimizer through the power line. The coupler is generally a capacitive single-ended direct coupler, that is, the coupler includes a capacitor, and the PLC circuit is coupled to the positive transmission line or the negative transmission line in the power line through the capacitor.

[0005] However, the above-mentioned coupler cannot effectively suppress the common-mode noise of the power line, resulting in poor signal-to-noise ratio of the PLC signal. SUMMARY

[0006] The present application provides an inverter and a PLC system, which can solve the technical problem that the coupler in the inverter cannot effectively suppress the common-mode noise of the power line, resulting in poor signal-to-noise ratio of the PLC signal.

[0007] In a first aspect, an inverter is provided, comprising: a power conversion circuit, a PLC circuit, a first transformer and a second transformer. The power conversion circuit is configured to be connected to a power line comprising a first transmission line and a second transmission line, and the PLC circuit is configured to transmit or receive a PLC signal via the power line. One end of a primary side of the first transformer is connected to one end of the PLC circuit, and a secondary side of the first transformer is connected in series between a port of the power conversion circuit and a port of the first transmission line. One end of a primary side of the second transformer is connected to the other end of the PLC circuit, and a secondary side of the second transformer is connected in series between the port of the power conversion circuit and a port of the second transmission line. The other end of the primary side of the first transformer is connected to the other end of the primary side of the second transformer.

[0008] In the inverter provided in the present application, the PLC circuit can be coupled to two transmission lines in the power line via the first transformer and the second transformer. Based on this coupling mode, common mode noise in the power line can be effectively suppressed, and the PLC signal coupled to the power line and the PLC signal coupled from the power line can have a high signal-to-noise ratio.

[0009] Optionally, the number of turns of the primary side of the first transformer can be equal to the number of turns of the primary side of the second transformer, and the number of turns of the secondary side of the first transformer can be equal to the number of turns of the secondary side of the second transformer.

[0010] By setting the number of turns of the primary sides of the two transformers to be the same and the number of turns of the secondary sides to be the same, the ability of the two transformers to suppress common mode noise in the power line can be effectively improved, thereby further improving the signal-to-noise ratio of the PLC signal.

[0011] Optionally, the number of turns of the primary side of the first transformer can be equal to the number of turns of the secondary side of the first transformer, and the number of turns of the primary side of the second transformer can be equal to the number of turns of the secondary side of the second transformer.

[0012] By setting the number of turns of the primary sides and the secondary sides of the two transformers in the inverter to be equal, on the one hand, the suppression effect on common mode noise in the power line can be ensured to be good, and on the other hand, the design and structural complexity of the inverter can be avoided.

[0013] Optionally, the PLC circuit can comprise a transmitting circuit and a receiving circuit. The output end of the transmitting circuit is connected to one end of the primary side of the first transformer and one end of the primary side of the second transformer, respectively, and the input end of the receiving circuit is connected to one end of the primary side of the first transformer and one end of the primary side of the second transformer, respectively.

[0014] It can be understood that the transmitting circuit is used for processing the transmitting signal, for example, for power amplifying the transmitting signal. The receiving circuit is used for processing the receiving signal, for example, for filtering the receiving signal. Since the transmitting circuit and the receiving circuit can share the primary sides of the two transformers to couple the PLC signal, the structural complexity of the inverter can be avoided from being increased, and the cost of the inverter can be avoided from being increased.

[0015] Optionally, the PLC circuit can include a transmitting circuit and a receiving circuit. The primary side of the first transformer includes a first winding and a second winding, and the primary side of the second transformer includes a third winding and a fourth winding. The output end of the transmitting circuit is connected with one end of the first winding and one end of the third winding respectively, and the other end of the first winding is connected with the other end of the third winding. The input end of the receiving circuit is connected with one end of the second winding and one end of the fourth winding respectively, and the other end of the second winding is connected with the other end of the fourth winding. Wherein, the number of turns of the first winding is equal to the number of turns of the third winding, and the number of turns of the second winding is equal to the number of turns of the fourth winding.

[0016] In the scheme provided in the present application, the transmitting circuit and the receiving circuit can also couple the PLC signal through different primary side windings, thereby effectively improving the flexibility of signal coupling.

[0017] Optionally, the first transmission line is a positive transmission line, and the second transmission line is a negative transmission line; or the first transmission line is a phase line, and the second transmission line is a zero line; or the first transmission line is a first phase line, and the second transmission line is a second phase line.

[0018] That is, in the scheme provided in the present application, the power line connected with the inverter can be a direct current line for transmitting direct current, or can be an alternating current line for transmitting alternating current. For example, if the power line is used to connect a photovoltaic panel, the power line can be a direct current line for transmitting direct current; if the power line is used to connect a box transformer or a power distribution cabinet, the power line can be an alternating current line for transmitting alternating current.

[0019] Optionally, the inverter can further include a capacitor, and the capacitor is connected in parallel with the port of the power conversion circuit. It can be understood that the capacitor can be connected across the two transmission lines of the power line, and can be used to eliminate differential mode interference, and the capacitor can also be referred to as a differential capacitor, a filter capacitor or an X capacitor. Alternatively, the inverter 20 can include a plurality of capacitors, each capacitor can be connected across a transmission line of the power line and the ground, and the capacitor can also be referred to as a Y capacitor, and the plurality of Y capacitors can be equivalent to a differential capacitor.

[0020] Optionally, the first transformer and the second transformer can be two independent magnetic rings. That is, the first transformer can be one magnetic ring, and the second transformer can be another independent magnetic ring.

[0021] Alternatively, the first transformer and the second transformer can be integrated on a circuit board, i.e. the first transformer and the second transformer can be on-board mounted. Moreover, the primary side and the secondary side of the first transformer and the primary side and the secondary side of the second transformer can be wound on the same magnetic core.

[0022] In a second aspect, a PLC system is provided, which comprises a data collector and at least one inverter provided in the first aspect above, the data collector being connected with the at least one inverter through power lines.

[0023] In an example, the PLC system can comprise a plurality of inverters, the data collector can be connected with the plurality of inverters through power lines and can perform PLC communication with the plurality of inverters.

[0024] In a third aspect, a PLC system is provided, which comprises an inverter provided in the first aspect above and at least one photovoltaic controller, the inverter being connected with the at least one photovoltaic controller through power lines.

[0025] In an example, the PLC system can comprise a plurality of photovoltaic controllers, the inverter can be connected with the plurality of photovoltaic controllers through power lines and can perform PLC communication with the plurality of photovoltaic controllers. The photovoltaic controller can be a photovoltaic optimizer or a photovoltaic shutdown device.

[0026] In summary, the present application provides an inverter and a PLC system. The inverter provided by the present application comprises a power conversion circuit, a PLC circuit, a first transformer and a second transformer. The power conversion circuit is configured to be connected with power lines, and the PLC circuit is coupled with first and second transmission lines in the power lines through the first and second transformers. Since the PLC circuit is coupled with the two transmission lines in the power lines through the two transformers, common mode noise in the power lines can be effectively suppressed. Moreover, since the PLC circuit is coupled with the power lines in an electromagnetic induction manner through the two transformers, noise generated by the power conversion circuit can also be effectively suppressed. Therefore, the inverter provided by the present application can ensure that the PLC circuit is coupled with PLC signals in the power lines and the signal-to-noise ratio of the PLC signals coupled from the power lines is high. BRIEF DESCRIPTION OF DRAWINGS

[0027] FIG. 1 is a structural schematic diagram of a photovoltaic power generation system provided by an embodiment of the present application;

[0028] FIG. 2 is a structural schematic diagram of another photovoltaic power generation system provided by an embodiment of the present application;

[0029] FIG. 3 is a structural schematic diagram of a coupler provided by an embodiment of the present application;

[0030] Fig. 4 is a structural schematic diagram of another coupler according to an embodiment of the present application;

[0031] Fig. 5 is a structural schematic diagram of yet another coupler according to an embodiment of the present application;

[0032] Fig. 6 is a structural schematic diagram of an inverter according to an embodiment of the present application;

[0033] Fig. 7 is a structural schematic diagram of another inverter according to an embodiment of the present application;

[0034] Fig. 8 is a structural schematic diagram of yet another inverter according to an embodiment of the present application. DETAILED DESCRIPTION

[0035] The inverter and PLC system according to the embodiments of the present application will be described in detail below with reference to the accompanying drawings. First, key terms related to the embodiments of the present application will be introduced.

[0036] Photovoltaic panel: also known as photovoltaic module, is a device for converting light energy into electrical energy.

[0037] PLC: also known as power line carrier communication, is a communication method for transmitting data (also known as carrier signal) by using power line. Since power line has a very strong support structure and is usually provided with three or more conductors (for example, there are usually three-phase conductors and one or two overhead ground wires), the carrier signal can be transmitted while the power line is used to transmit power frequency current, which is both economical and very reliable.

[0038] Inverter: also known as power converter, is a DC-to-AC power supply, which is used to convert the DC power of photovoltaic panel into AC power.

[0039] Box transformer: a short name of box transformer, which has a low-voltage distribution cabinet and a transformer inside.

[0040] Data collector: a controller device for collecting and controlling the inverter, which can communicate with the inverter through PLC technology.

[0041] Photovoltaic controller: including photovoltaic optimizer or photovoltaic shutdown device. The photovoltaic optimizer is a DC-to-DC power supply, which is used to convert the DC power of photovoltaic panel into adjustable DC power to perform MPPT on the photovoltaic panel and ensure the maximum output power of the photovoltaic panel. One photovoltaic optimizer can be connected to one or more photovoltaic panels. The photovoltaic shutdown device is a switch that can cut off the output of the photovoltaic panel, and generally one photovoltaic panel is provided with one photovoltaic shutdown device.

[0042] Fig. 1 is a structural schematic diagram of a photovoltaic power generation system according to an embodiment of the present application. As shown in Fig. 1, the photovoltaic power generation system can include photovoltaic panels 10, inverters 20 and a data collector 30. The inverters 20 can be connected to a plurality of photovoltaic panels 10 (only one photovoltaic panel 10 is shown in Fig. 1) and can convert direct current output by the plurality of photovoltaic panels 10 into alternating current. The data collector 30 can be connected to the plurality of inverters 20 through power lines and can exchange information through the power lines, for example, the data collector 30 and the inverters 20 can exchange information such as service query and command control. In addition, the data collector 30 can be a master of a PLC and the inverters 20 can be slaves of the PLC.

[0043] With continued reference to Fig. 1, the photovoltaic power generation system can further include a box transformer 40, which can be connected to the plurality of inverters 20 through power lines and can convert voltage of alternating current output by the plurality of inverters 20. The data collector 30 can be disposed in the box transformer 40 or in the vicinity of the box transformer 40, and the plurality of inverters 20 can be connected to the data collector 30 through the box transformer 40.

[0044] Optionally, the inverters 20 in the photovoltaic power generation system can also be micro inverters, and the photovoltaic power generation system can include a plurality of micro inverters. Each micro inverter can be connected to one or more photovoltaic panels 10 and can convert direct current output by the one or more photovoltaic panels 10 into alternating current and transmit the alternating current to a distribution cabinet through power lines. The data collector 30 can be disposed in the distribution cabinet and can communicate with the plurality of micro inverters through the power lines.

[0045] Fig. 2 is a structural schematic diagram of another photovoltaic power generation system according to an embodiment of the present application. As shown in Fig. 2, the photovoltaic power generation system can include a plurality of photovoltaic panels 10, inverters 20 and a plurality of photovoltaic controllers 50. The photovoltaic controllers 50 can be photovoltaic optimizers or photovoltaic shutdown devices, and each photovoltaic panel 10 can be connected to one photovoltaic controller 50, i.e., the photovoltaic controller 50 can be a component-level controller. The photovoltaic shutdown device can shut down output of the photovoltaic panel 10, and the photovoltaic optimizer can optimize power of the photovoltaic panel 10.

[0046] As can be seen from Fig. 2, the inverters 20 can be connected to the plurality of photovoltaic panels 10 through power lines and can convert direct current output by the plurality of photovoltaic panels 10 into alternating current. In addition, the inverters 20 can communicate with the plurality of photovoltaic controllers 50 through the power lines to issue control instructions to the plurality of photovoltaic controllers 50. That is, the inverters 20 can be masters of a PLC and the plurality of photovoltaic controllers 50 can be slaves of the PLC.

[0047] It can be understood that, in the photovoltaic power generation system shown in FIG. 1, the power line between the inverter 20 and the data collector 30 is used to transmit alternating current, and therefore the PLC communication based on the power line can also be referred to as alternating current PLC communication. In the photovoltaic power generation system shown in FIG. 2, the power line between the inverter 20 and the photovoltaic controller 50 is used to transmit direct current, and therefore the PLC communication based on the power line can also be referred to as direct current PLC communication.

[0048] It can also be understood that, the communication between the inverter 20 and the data collector 30, or the communication between the inverter 20 and the photovoltaic controller 50, can be performed in a half-duplex manner. That is, each of the two devices performing PLC communication can send a signal to the other device, but the two devices do not send signals at the same time.

[0049] FIG. 3 is a structural schematic diagram of a coupler in an inverter according to an embodiment of the present application. As shown in FIG. 3, the inverter 20 generally includes a power conversion circuit, a PLC circuit, and a coupler. Since the power signal transmitted by the power line is a high-voltage signal, and the PLC signal transmitted by the PLC circuit is a low-voltage signal, the low-voltage signal needs to be coupled to the power line through the coupler. Referring to FIG. 3, the coupler can be a transformer, and the transformer can be connected to the PLC circuit and one transmission line (for example, a negative transmission line, a zero line, or a certain phase line) of the power line, respectively. The coupling mode of the coupler shown in FIG. 3 is also referred to as single-ended magnetic isolation coupling. The coupler cannot suppress the common-mode noise of the power line, resulting in a poor signal-to-noise ratio of the PLC signal.

[0050] FIG. 4 is a structural schematic diagram of another coupler in an inverter according to an embodiment of the present application. As shown in FIG. 4, the coupler in the inverter 20 can include two capacitors, and the PLC circuit can be directly connected to one transmission line of the power line through the two capacitors. The coupling mode of the coupler shown in FIG. 4 is also referred to as capacitive single-ended direct coupling. The coupler cannot suppress the common-mode noise, and the direct coupling mode cannot effectively suppress the noise generated by the power conversion circuit, resulting in a low signal-to-noise ratio of the PLC signal.

[0051] FIG. 5 is a structural schematic diagram of still another coupler in an inverter according to an embodiment of the present application. As shown in FIG. 5, the coupler in the inverter 20 can include two capacitors, and the PLC circuit can be directly connected to two transmission lines of the power line through the two capacitors. The coupling mode of the coupler shown in FIG. 5 is also referred to as capacitive differential direct coupling. The coupler can suppress the common-mode noise of the power line to a certain extent, but the direct coupling mode cannot effectively suppress the noise generated by the power conversion circuit, resulting in a low signal-to-noise ratio of the PLC signal.

[0052] The embodiment of the present application provides a kind of inverter, which can be applied to photovoltaic power generation system such as shown in Figure 1 or Figure 2.And the coupler in the inverter adopts the coupling mode of differential magnetic isolation, can better inhibit the common-mode noise of power line, ensure that the signal-to-noise ratio of PLC signal is higher.As shown in Figure 6, the inverter provided by the embodiment of the present application includes: power conversion circuit 201, power line communication PLC circuit 202, first transformer T1 and second transformer T2.

[0053] Wherein, power conversion circuit 201 is used to be connected with power line, and the power line includes first transmission line L1 and second transmission line L2.It can be understood that if the power line is connected with photovoltaic controller 50, the power conversion circuit 201 is used to receive the direct current transmitted by photovoltaic panel through the power line, and direct current is converted into alternating current, i.e.the power line is used to transmit direct current.If the power line is connected with data collector 30, the power conversion circuit 201 is used to transmit alternating current to the power line after converting the direct current provided by photovoltaic panel into alternating current, i.e.the power line is used to transmit alternating current.

[0054] Continue to refer to Figure 6, one end of the primary side (the number of turns is N1) of the first transformer T1 is connected with one end of PLC circuit 202, and the secondary side (the number of turns is N2) of the first transformer T1 is connected between the port of power conversion circuit 201 and the port of first transmission line L1.

[0055] One end of the primary side (the number of turns is N1') of second transformer T2 is connected with the other end of PLC circuit 202, and the secondary side (the number of turns is N2') of second transformer T2 is connected between the port of power conversion circuit 201 and the port of second transmission line L2.The other end of the primary side of the first transformer T1 is connected with the other end of the primary side of the second transformer T2.

[0056] It can be understood that if the power line is connected with photovoltaic controller 50, the port of power conversion circuit 201 described above can be direct current input port, i.e.the port for receiving direct current.If the power line is connected with data collector 30, the port of power conversion circuit 201 described above can be alternating current output port, i.e.the port for outputting alternating current.

[0057] It can also be understood that the first transmission line L1 has two ports, one of which is connected with the secondary side of the first transformer T1, and the other is connected with photovoltaic controller 50 or data collector 30.The second transmission line L2 also has two ports, one of which is connected with the secondary side of the second transformer T2, and the other is connected with photovoltaic controller 50 or data collector 30.

[0058] In combination with FIG. 6 and the above description, the PLC circuit 202 can be coupled to the first transmission line L1 and the second transmission line L2 in the power line through the first transformer T1 and the second transformer T2, and transmit or receive PLC signals through the first transmission line L1 and the second transmission line L2 in the power line. Since the coupling mode can be coupled to the two transmission lines in the power line respectively, and is coupled to the power line in an electromagnetic induction manner through two transformers, the coupling mode belongs to differential magnetic isolation coupling. Based on the differential magnetic isolation coupling mode, common mode noise in the power line can be effectively suppressed, and noise generated by the power conversion circuit can be effectively suppressed. Thus, it can be ensured that the PLC circuit coupled to the PLC signal in the power line or the PLC signal coupled from the power line has a high signal-to-noise ratio.

[0059] In summary, the embodiment of the present application provides an inverter, and the PLC circuit in the inverter can be coupled to two transmission lines in the power line through a first transformer and a second transformer. Based on the coupling mode, common mode noise in the power line can be effectively suppressed, and noise generated by the power conversion circuit can be effectively suppressed, so as to ensure that the PLC signal has a high signal-to-noise ratio.

[0060] It can be understood that the number of turns N1 of the primary side, the number of turns N2 of the secondary side of the first transformer T1, and the number of turns N1' of the primary side, the number of turns N2' of the secondary side of the second transformer T2 can be flexibly set according to the requirements of the application scene, and the embodiment of the present application does not limit this. Wherein N1, N2, N1' and N2' can be integers greater than 1.

[0061] Optionally, the number of turns N1 of the primary side of the first transformer T1 can be equal to the number of turns N1' of the primary side of the second transformer T2, and the number of turns N2 of the secondary side of the first transformer T1 can be equal to the number of turns N2' of the secondary side of the second transformer T2. By setting the number of turns of the primary side of the two transformers to be the same, and the number of turns of the secondary side to be the same, the common mode noise in the power line can be effectively offset, that is, the ability of the two transformers to suppress the common mode noise in the power line is improved, thereby further improving the signal-to-noise ratio of the PLC signal.

[0062] It can be understood that the first transformer T1 can be equivalent to a first inductor and a second inductor, and the second transformer T2 can also be equivalent to a third inductor and a fourth inductor. Wherein the inductor coil of the first inductor is the primary side of the first transformer T1, and the inductor coil of the second inductor is the secondary side of the first transformer T1. The inductor coil of the third inductor is the primary side of the second transformer T2, and the inductor coil of the fourth inductor is the secondary side of the second transformer T2.

[0063] And, the number of turns N1 of the inductor coil of the first inductor can be equal to the number of turns N1' of the inductor coil of the third inductor, and the number of turns N2 of the inductor coil of the second inductor can be equal to the number of turns N2' of the inductor coil of the fourth inductor. That is, the first inductor and the third inductor can be a set of symmetrical inductors, and the second inductor and the fourth inductor can be a set of symmetrical inductors. By setting two sets of symmetrical inductors to couple the PLC signal of the PLC circuit or to couple the PLC signal from the power line, it can be ensured that the noise on the first transmission line L1 and the second transmission line L2 is effectively cancelled, that is, the common mode noise of the power line is effectively suppressed, and the signal-to-noise ratio of the PLC signal is improved.

[0064] Optionally, in order to ensure better suppression effect on the common mode noise, the magnetic core of the first transformer T1 and the magnetic core of the second transformer T2 can be the same. Wherein, the same magnetic core can mean that the material, shape and size of the magnetic core are the same. For example, the first transformer T1 and the second transformer T2 can be integrated in one device and can share the same magnetic core.

[0065] Optionally, the number of turns of the primary side N1 of the first transformer T1 can be equal to the number of turns N2 of the secondary side of the first transformer T1, and the number of turns of the primary side of the second transformer T2 N1' can be equal to the number of turns N2' of the secondary side of the second transformer T2. That is, the number of turns of the first transformer T1 and the second transformer T2 satisfies: N1=N2=N1'=N2'.

[0066] By setting the number of turns of the primary side and the secondary side of the two transformers in the inverter 20 to be equal, on the one hand, it can ensure better suppression effect on the common mode noise in the power line, and on the other hand, it can avoid increasing the design and structural complexity of the inverter 20.

[0067] FIG. 7 is a structural schematic diagram of another inverter provided by an embodiment of the present application. Optionally, as shown in FIG. 7, the PLC circuit 202 can include a sending circuit 2021 and a receiving circuit 2022. Wherein, the sending circuit 2021 is configured to process a sending signal sent to other devices (such as the data collector 30 or the photovoltaic controller 50), for example, to perform power amplification on the sending signal. The receiving circuit 2022 is configured to process a receiving signal from other devices, for example, to perform filtering on the receiving signal.

[0068] It can be understood that the sending signal can refer to the PLC signal sent to the data collector 30 or the photovoltaic controller 50 through the power line, and the receiving signal can refer to the PLC signal received from the data collector 30 or the photovoltaic controller 50 through the power line.

[0069] Optionally, referring to FIG. 7, the output end of the transmitting circuit 2021 is connected to one end of the primary side of the first transformer T1 and one end of the primary side of the second transformer T2 respectively, and the input end of the receiving circuit 2022 is connected to one end of the primary side of the first transformer T1 and one end of the primary side of the second transformer T2 respectively. That is, the transmitting circuit 2021 and the receiving circuit 2022 can share the primary side of the two transformers to realize the coupling of the transmitting signal and the receiving signal. Thus, the increase of the structural complexity of the inverter 20 and the cost of the inverter can be effectively avoided.

[0070] FIG. 8 is a structural schematic diagram of another transformer provided by the embodiment of the present application. Optionally, as shown in FIG. 8, the primary side of the first transformer T1 can include a first winding (with a number of turns N1) and a second winding (with a number of turns N3), and the primary side of the second transformer T2 can include a third winding (with a number of turns N1') and a fourth winding (with a number of turns N3'). Wherein, the output end of the transmitting circuit 2021 is connected to one end of the first winding and one end of the third winding respectively, and the other end of the first winding is connected to the other end of the third winding. The input end of the receiving circuit 2022 is connected to one end of the second winding and one end of the fourth winding respectively, and the other end of the second winding is connected to the other end of the fourth winding. That is, the transmitting circuit 2021 and the receiving circuit 2022 can couple the PLC signal through independent primary side windings, thereby effectively improving the flexibility of the PLC signal coupling.

[0071] It can be understood that the number of turns N1 of the first winding can be equal to the number of turns N1' of the third winding, and the number of turns N3 of the second winding can be equal to the number of turns N3' of the fourth winding. Moreover, the number of turns N1 of the first winding can be equal to or different from the number of turns N3 of the second winding, and the number of turns N1' of the third winding can be equal to or different from the number of turns N3' of the fourth winding.

[0072] In the embodiment of the present application, in order to ensure a better suppression effect on common mode noise, the number of turns N1 of the first winding and the number of turns N3 of the second winding can be equal, and both are equal to the number of turns N2 of the secondary side of the first transformer T1. Similarly, the number of turns N1' of the third winding and the number of turns N3' of the fourth winding can be equal, and both are equal to the number of turns N2' of the secondary side of the second transformer T2.

[0073] Optionally, if the power line connected to the inverter 20 is used to transmit direct current, the power line can be a direct current line, and the first transmission line L1 in the power line can be a positive transmission line, and the second transmission line L2 can be a negative transmission line. That is, the PLC circuit 202 can inject the PLC signal into the positive transmission line and the negative transmission line.

[0074] If the power line to which the inverter 20 is connected is used to transmit AC power, the power line can be an AC line, for example, can be a three-phase AC line. The first transmission line L1 in the power line can be a phase line, and the second transmission line L2 can be a zero line. Alternatively, the first transmission line L1 is a first phase line, and the second transmission line L2 can be a second phase line. That is, the PLC circuit 202 can inject a PLC signal into a phase line and a zero line, or into two phase lines.

[0075] Optionally, with reference to FIGS. 6-8, the inverter 20 can further include a capacitor C1, which can be connected in parallel with the port of the power conversion circuit 201.

[0076] As shown in FIGS. 6-8, the capacitor C1 can be connected across two transmission lines of the power line, and can be used to eliminate differential mode interference. The capacitor C1 can also be referred to as a differential capacitor, a filter capacitor, or an X capacitor. Alternatively, the inverter 20 can include a plurality of capacitors C1, each of which can be connected across a transmission line of the power line and ground. The capacitor C1 can also be referred to as a Y capacitor, and the plurality of Y capacitors can be equivalent to a differential capacitor.

[0077] Since the PLC signal has a high frequency, and the capacitor has the characteristics of passing high frequency and blocking low frequency, and passing AC and blocking DC, the impedance of the capacitor C1 to the PLC signal is usually less than 0.1 ohm (Ω). Thus, if the PLC circuit 202 directly injects or extracts a PLC signal into or from the power line, the PLC signal will be short-circuited by the capacitor C1 (i.e., the energy of the PLC signal is all absorbed by the capacitor C1). Therefore, in the embodiments of the present application, the PLC signal needs to be effectively coupled to the power line or from the power line to the PLC circuit 202 by the first transformer T1 and the second transformer T2, that is, the effective injection and extraction of the PLC signal can be achieved by two transformers.

[0078] As an optional implementation, the first transformer T1 and the second transformer T2 can be two magnetic rings independent of each other. That is, the first transformer T1 (i.e., the first inductor and the second inductor) can be one magnetic ring, and the second transformer T2 (i.e., the third inductor and the fourth inductor) can be another magnetic ring.

[0079] As another optional implementation, the first transformer T1 and the second transformer T2 are integrated on a circuit board, that is, the first transformer T1 and the second transformer T2 can be mounted on the board. Moreover, the primary side and the secondary side of the first transformer, and the primary side and the secondary side of the second transformer can be wound on the same magnetic core.

[0080] It can be understood that the inverter provided by the embodiments of the present application can include two groups of communication circuits, and each group of communication circuits includes a PLC circuit, a first transformer and a second transformer. One group of communication circuits can communicate with the data collector 30 through the power line, and the other group of communication circuits can communicate with the photovoltaic controller 50 through the power line.

[0081] In summary, the embodiments of the present application provide an inverter, and the power conversion circuit of the inverter is used to be connected with the power line, and the PLC circuit is coupled with the first transmission line and the second transmission line in the power line through the first transformer and the second transformer. Since the PLC circuit is coupled with the two transmission lines in the power line through the two transformers, the common mode noise in the power line can be effectively suppressed. Moreover, since the PLC circuit is coupled with the power line in the form of electromagnetic induction through the two transformers, the noise generated by the power conversion circuit can be effectively suppressed. Therefore, the inverter provided by the embodiments of the present application can ensure that the PLC circuit is coupled to the PLC signal in the power line, and the signal-to-noise ratio of the PLC signal coupled from the power line is high.

[0082] The embodiments of the present application also provide a PLC system, as shown in FIG. 1, which includes the data collector 30 and at least one inverter 20 provided by the above-mentioned embodiments, and the data collector 30 is connected with the at least one inverter 20 through the power line. Since the power line is used to transmit alternating current, the PLC system can be called an alternating current PLC system.

[0083] For example, the PLC system can include a plurality of inverters 20, and the data collector 30 can be connected with the plurality of inverters 20 through the power line and perform PLC communication with the plurality of inverters 20.

[0084] The embodiments of the present application also provide another PLC system, as shown in FIG. 2, which includes the inverter 20 provided by the above-mentioned embodiments and at least one photovoltaic controller 50, and the inverter 20 is connected with the at least one photovoltaic controller 50 through the power line. Since the power line is used to transmit direct current, the PLC system can be called a direct current PLC system.

[0085] For example, the PLC system can include a plurality of photovoltaic controllers 50, and the inverter 20 can be connected with the plurality of photovoltaic controllers 50 through the power line and perform PLC communication with the plurality of photovoltaic controllers 50. The photovoltaic controller 50 can be a photovoltaic optimizer or a photovoltaic shutdown device.

[0086] In the embodiments of the present application, the terms "first", "second" and "third" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance. The term "at least one" means one or more, and "multiple" means two or more.

[0087] The above merely provides the optional embodiments of the present application, but the protection scope of the present application is not limited thereto, and any modification or replacement within the technical range disclosed by the present application can be easily thought by those skilled in the art, and these modifications or replacements should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An inverter, characterized by comprising: The inverter comprises a power conversion circuit, a power line communication (PLC) circuit, a first transformer and a second transformer; The power conversion circuit is configured to be connected with a power line, and the power line comprises a first transmission line and a second transmission line; The PLC circuit is configured to send or receive a PLC signal through the power line; One end of a primary side of the first transformer is connected with one end of the PLC circuit, and a secondary side of the first transformer is connected in series between a port of the power conversion circuit and a port of the first transmission line; One end of a primary side of the second transformer is connected with the other end of the PLC circuit, and a secondary side of the second transformer is connected in series between the port of the power conversion circuit and a port of the second transmission line; The other end of the primary side of the first transformer is connected with the other end of the primary side of the second transformer.

2. The inverter of claim 1, wherein, The number of turns of the primary side of the first transformer is equal to the number of turns of the primary side of the second transformer, and the number of turns of the secondary side of the first transformer is equal to the number of turns of the secondary side of the second transformer.

3. The inverter of claim 2, wherein, The number of turns of the primary side of the first transformer is equal to the number of turns of the secondary side of the first transformer, and the number of turns of the primary side of the second transformer is equal to the number of turns of the secondary side of the second transformer.

4. The inverter according to any one of claims 1 to 3, characterized by The PLC circuit comprises a sending circuit and a receiving circuit; The output end of the sending circuit is connected with one end of the primary side of the first transformer and one end of the primary side of the second transformer respectively, and the input end of the receiving circuit is connected with one end of the primary side of the first transformer and one end of the primary side of the second transformer respectively.

5. The inverter according to claim 1 or 2, characterized by The PLC circuit comprises a sending circuit and a receiving circuit; the primary side of the first transformer comprises a first winding and a second winding, and the primary side of the second transformer comprises a third winding and a fourth winding; The output end of the sending circuit is connected with one end of the first winding and one end of the third winding respectively, and the other end of the first winding is connected with the other end of the third winding; The input end of the receiving circuit is connected with one end of the second winding and one end of the fourth winding respectively, and the other end of the second winding is connected with the other end of the fourth winding; The number of turns of the first winding is equal to the number of turns of the third winding, and the number of turns of the second winding is equal to the number of turns of the fourth winding.

6. The inverter according to any one of claims 1 to 5, characterized by The first transmission line is a positive transmission line, and the second transmission line is a negative transmission line; Alternatively, the first transmission line is a phase line, and the second transmission line is a zero line; Alternatively, the first transmission line is a first phase line, and the second transmission line is a second phase line.

7. The inverter according to any one of claims 1 to 6, characterized by The inverter further comprises a capacitor; The capacitor is connected in parallel with the port of the power conversion circuit.

8. The inverter according to any one of claims 1 to 7, characterized by The first transformer and the second transformer are two independent magnetic rings; Alternatively, the first transformer and the second transformer are integrated on a circuit board.

9. A PLC system characterized by comprising: The PLC system comprises a data collector and at least one inverter as claimed in any one of claims 1 to 8; the data collector is connected with at least one inverter through the power line.

10. A PLC system characterized by comprising: The PLC system comprises the inverter as claimed in any one of claims 1 to 8, and at least one photovoltaic controller; the inverter is connected with the at least one photovoltaic controller through the power line.

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