Inverter and PLC system

Abstract

The utility model provides an inverter and a PLC system, and belongs to the field of photovoltaic technology. In the inverter provided by the utility model, a power conversion circuit is used for being connected with a power line, and a PLC circuit is coupled with a first transmission line and a second transmission line in the power line through a first transformer and a second transformer. The PLC circuit is coupled with the two transmission lines in the power line through the two transformers, so that common-mode noise in the power line can be effectively suppressed. Moreover, the PLC circuit is coupled with the power line through two transformers in an electromagnetic induction mode, so that the noise generated by the power conversion circuit can be effectively suppressed. Therefore, the inverter provided by the invention can ensure that the signal-to-noise ratio of the PLC circuit coupled to the PLC signal in the power line and the signal-to-noise ratio of the PLC signal coupled from the power line are high.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to an inverter and a PLC system. Background Art

[0002] Photovoltaic (PV) power generation systems generally include photovoltaic panels, photovoltaic optimizers, inverters and other devices. 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 the maximum output power of the photovoltaic panel. Usually, each photovoltaic panel can be connected to a photovoltaic optimizer to achieve component-level power optimization. In addition, the inverter and the photovoltaic optimizer can communicate through power line communication (PLC) technology to achieve information interaction operations such as business query and command control.

[0003] The inverter generally includes a power conversion circuit, a monitoring circuit and a communication circuit. The communication circuit may adopt PLC technology, and the communication circuit may include a modulation and demodulation circuit, a PLC circuit and a coupler. Among them, the modulation and demodulation circuit is used to realize the modulation and demodulation of the PLC signal, and the PLC circuit is coupled to the power line through the coupler, and is used to exchange the PLC signal 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.

[0004] However, the above coupler cannot effectively suppress the common mode noise of the power line, resulting in a poor signal-to-noise ratio of the PLC signal. Utility Model Content

[0005] 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 a poor signal-to-noise ratio of the PLC signal.

[0006] In a first aspect, an inverter is provided, which includes: a power conversion circuit, a PLC circuit, a first transformer and a second transformer. The power conversion circuit is used to connect to a power line, which includes a first transmission line and a second transmission line; the PLC circuit is used to send or receive a PLC signal through the power line. One end of the primary side of the first transformer is connected to one end of the PLC circuit, and the 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 the primary side of the second transformer is connected to the other end of the PLC circuit, and the secondary side of the second transformer is connected in series between a 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.

[0007] In the inverter provided by the present application, the PLC circuit can be coupled to two transmission lines in the power line through the first transformer and the second transformer. Based on this coupling method, the common mode noise in the power line can be effectively suppressed, ensuring 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.

[0008] Optionally, the number of turns of the primary side of the first transformer may 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 may be equal to the number of turns of the secondary side of the second transformer.

[0009] 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 lines can be effectively improved, thereby further improving the signal-to-noise ratio of the PLC signal.

[0010] Optionally, the number of turns of the primary side of the first transformer may 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 may be equal to the number of turns of the secondary side of the second transformer.

[0011] By setting the number of turns of the primary and secondary sides of the two transformers in the inverter to be equal, on the one hand, it can ensure a 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.

[0012] Optionally, the PLC circuit may include: a transmitting circuit and a receiving circuit, wherein the output end of the transmitting circuit is respectively connected to one end of the primary side of the first transformer and one end of the primary side of the second transformer, and the input end of the receiving circuit is respectively connected to one end of the primary side of the first transformer and one end of the primary side of the second transformer.

[0013] It can be understood that the transmitting circuit is used to process the transmitting signal, for example, to amplify the power of the transmitting signal. The receiving circuit is used to process the receiving signal, for example, to filter 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, it is possible to avoid increasing the structural complexity of the inverter and the cost of the inverter.

[0014] Optionally, the PLC circuit may 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 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 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. 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.

[0015] In the solution provided in the present application, the transmitting circuit and the receiving circuit can also couple the PLC signal through different primary windings, thereby effectively improving the flexibility of signal coupling.

[0016] 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 neutral line; or, the first transmission line is a first phase line, and the second transmission line is a second phase line.

[0017] That is, in the solution provided by the present application, the power line connected to the inverter can be a DC line for transmitting direct current, or an AC line for transmitting alternating current. For example, if the power line is used to connect a photovoltaic panel, the power line can be a DC line for transmitting direct current; if the power line is used to connect a box transformer or a distribution cabinet, the power line can be an AC line for transmitting alternating current.

[0018] Optionally, the inverter may further include: a capacitor; the capacitor is connected in parallel with the port of the power conversion circuit. It is understandable that the capacitor can be connected across two transmission lines of the power line, can be used to eliminate differential mode interference, and the capacitor can also be called a differential capacitor, a filter capacitor or an X capacitor. Alternatively, the inverter 20 may include multiple capacitors, each of which can be connected across a transmission line of the power line and the ground, the capacitor can also be called a Y capacitor, and the multiple Y capacitors can be equivalent to differential capacitors.

[0019] Optionally, the first transformer and the second transformer may be two independent magnetic rings, that is, the first transformer may be one magnetic ring, and the second transformer may be another independent magnetic ring.

[0020] Alternatively, the first transformer and the second transformer may be integrated on a circuit board, that is, the first transformer and the second transformer may be mounted on a board. Furthermore, the primary and secondary sides of the first transformer, and the primary and secondary sides of the second transformer may be wound on the same magnetic core.

[0021] In a second aspect, a PLC system is provided, comprising: a data collector, and at least one inverter as provided in the first aspect, wherein the data collector is connected to the at least one inverter via a power line.

[0022] For example, the PLC system may include multiple inverters, and the data collector may be connected to the multiple inverters via power lines and perform PLC communication with the multiple inverters.

[0023] In a third aspect, a PLC system is provided, which includes: the inverter provided in the first aspect, and at least one photovoltaic controller; the inverter is connected to the at least one photovoltaic controller via a power line.

[0024] For example, the PLC system may include multiple photovoltaic controllers, and the inverter may be connected to the multiple photovoltaic controllers via power lines and perform PLC communication with the multiple photovoltaic controllers. The photovoltaic controller may be a photovoltaic optimizer or a photovoltaic shut-off device.

[0025] In summary, the present application provides an inverter and a PLC system. The inverter provided in the present application includes a power conversion circuit, a PLC circuit, a first transformer and a second transformer. Among them, the power conversion circuit is used to connect to 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 two transformers, the common mode noise in the power line can be effectively suppressed. And because the PLC circuit is coupled with the power line by electromagnetic induction through two transformers, the noise generated by the power conversion circuit can also be effectively suppressed. It can be seen that the inverter provided in 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a structural schematic diagram of a photovoltaic power generation system provided in an embodiment of the present application;

[0027] Figure 2 is a structural schematic diagram of another photovoltaic power generation system provided in an embodiment of the present application;

[0028] Figure 3is a structural schematic diagram of a coupler provided in an embodiment of the present application;

[0029] Figure 4 is a schematic diagram of the structure of another coupler provided in an embodiment of the present application;

[0030] Figure 5 is a structural schematic diagram of another coupler provided in an embodiment of the present application;

[0031] Figure 6 is a structural schematic diagram of an inverter provided in an embodiment of the present application;

[0032] Figure 7 is a structural schematic diagram of another inverter provided in an embodiment of the present application;

[0033] Figure 8 It is a structural schematic diagram of another inverter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0034] The inverter and PLC system provided by the embodiment of the present application are described in detail below in conjunction with the accompanying drawings. First, the key terms involved in the embodiment of the present application are introduced.

[0035] Photovoltaic panel: also known as photovoltaic module, is a device used to convert light energy into electrical energy.

[0036] PLC: Also known as power line carrier communication, it is a communication method that uses power lines to transmit data (also known as carrier signals). Since power lines have a very strong support structure and are usually equipped with more than three conductors (for example, there are usually three-phase good conductors and one or two overhead ground wires), it is economical and reliable to use power lines to transmit industrial frequency current while also transmitting carrier signals.

[0037] Inverter: Also known as a power converter, it is a DC to AC power supply that is used to convert the direct current of the photovoltaic panel into alternating current.

[0038] Box transformer: The abbreviation of box-type transformer, which contains a low-voltage distribution cabinet and transformer.

[0039] Data collector: A controller device used to collect and control inverters, which can communicate with the inverter through PLC technology.

[0040] Photovoltaic controller: includes photovoltaic optimizer or photovoltaic shut-off device. Among them, photovoltaic optimizer is a DC-to-DC power supply, which is used to convert the direct current of photovoltaic panels into adjustable direct current to perform MPPT on photovoltaic panels to ensure the maximum output power of photovoltaic panels. A photovoltaic optimizer can be connected to one or more photovoltaic panels. Photovoltaic shut-off device is a switch that can cut off the output of photovoltaic panels. Generally, one photovoltaic panel is equipped with a photovoltaic shut-off device.

[0041] Figure 1 is a schematic diagram of a photovoltaic power generation system provided in an embodiment of the present application, such as Figure 1 As shown, the photovoltaic power generation system may include a photovoltaic panel 10, an inverter 20 and a data collector 30. The inverter 20 may be connected to a plurality of photovoltaic panels 10 ( Figure 1 Only one photovoltaic panel 10 is schematically shown in the figure, and the data collector 30 can convert the direct current output by multiple photovoltaic panels 10 into alternating current. The data collector 30 can be connected to multiple inverters 20 through power lines, and exchange information through the power lines. For example, information exchange operations such as business query and command control can be performed between the data collector 30 and the inverter 20. In addition, the data collector 30 can be the host of the PLC, and the inverter 20 can be the slave of the PLC.

[0042] Continue to refer Figure 1 The photovoltaic power generation system may further include a box transformer 40, which may be connected to the plurality of inverters 20 via power lines and may perform voltage conversion on the AC power output by the plurality of inverters 20. The data collector 30 may be disposed in the box transformer 40 or near the box transformer 40, and the plurality of inverters 20 may be connected to the data collector 30 via the box transformer 40.

[0043] Optionally, the inverter 20 in the photovoltaic power generation system may also be a micro-inverter, and the photovoltaic power generation system may include multiple micro-inverters, each of which may be connected to one or more photovoltaic panels 10, and may convert the direct current output by the one or more photovoltaic panels 10 connected thereto into alternating current, and transmit the alternating current to a distribution cabinet via a power line. The distribution cabinet may be provided with a data collector 30, which may communicate with multiple micro-inverters via a power line.

[0044] Figure 2 Schematic diagram of another photovoltaic power generation system provided in the embodiment of the present application. Figure 2 As shown, the photovoltaic power generation system may include a plurality of photovoltaic panels 10, an inverter 20, and a plurality of photovoltaic controllers 50. The photovoltaic controller 50 may be a photovoltaic optimizer or a photovoltaic shut-off device, and each photovoltaic panel 10 may be connected to a photovoltaic controller 50, that is, the photovoltaic controller 50 may be a component-level controller. The photovoltaic shut-off device may shut off the output of the photovoltaic panel 10, and the photovoltaic optimizer may optimize the power of the photovoltaic panel 10.

[0045] from Figure 2It can be seen that the inverter 20 can be connected to the multiple photovoltaic panels 10 through the power line, and can convert the direct current output by the multiple photovoltaic panels 10 into alternating current. In addition, the inverter 20 can also communicate with multiple photovoltaic controllers 50 through the power line, so as to send control instructions to the multiple photovoltaic controllers 50. That is, the inverter 20 can be the host of the PLC, and the multiple photovoltaic controllers 50 can be the slaves of the PLC.

[0046] It is understandable that in Figure 1 In the photovoltaic power generation system shown, the power line between the inverter 20 and the data collector 30 is used to transmit AC power, so the PLC communication based on the power line can also be called AC PLC communication. Figure 2 In the photovoltaic power generation system shown, the power line between the inverter 20 and the photovoltaic controller 50 is used to transmit direct current, so the PLC communication based on the power line can also be called direct current PLC communication.

[0047] It can also be understood that the inverter 20 and the data collector 30, or the inverter 20 and the photovoltaic controller 50, can communicate in a half-duplex manner. That is, each of the two devices communicating through PLC can send a signal to the other end, but the two devices will not send a signal at the same time.

[0048] Figure 3 is a schematic diagram of the structure of a coupler in an inverter provided in an embodiment of the present application, such as Figure 3 As shown, 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, it is necessary to couple the low voltage signal to the power line through a coupler. Figure 3 The coupler may be a transformer, and the transformer may be connected to the PLC circuit and a transmission line in the power line (eg, a negative transmission line, a neutral line, or a phase line) respectively. Figure 3 The coupling mode of the coupler shown is also called 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.

[0049] Figure 4 is a schematic diagram of the structure of another coupler in an inverter provided in an embodiment of the present application, such as Figure 4 As shown, the coupler in the inverter 20 may include two capacitors, and the PLC circuit may be directly connected to one of the transmission lines in the power line through the two capacitors. Figure 4The coupling method of the coupler shown is also called capacitive single-ended direct coupling. The coupler cannot suppress common-mode noise, and the direct coupling method cannot effectively suppress the noise generated by the power conversion circuit, which leads to a low signal-to-noise ratio of the PLC signal.

[0050] Figure 5 is a structural diagram of a coupler in another inverter provided in an embodiment of the present application, such as Figure 5 As shown, the coupler in the inverter 20 may include two capacitors, and the PLC circuit may be directly connected to two transmission lines in the power line through the two capacitors. Figure 5 The coupling method of the coupler shown is also called capacitive differential direct coupling. The coupler can suppress the common-mode noise of the power line to a certain extent, but the direct coupling method cannot effectively suppress the noise generated by the power conversion circuit, which leads to a low signal-to-noise ratio of the PLC signal.

[0051] The present application provides an inverter, which can be applied to Figure 1 or Figure 2 In the photovoltaic power generation system shown in FIG. 1 , the coupler in the inverter adopts a differential magnetic isolation coupling method, which can effectively suppress the common mode noise of the power line and ensure that the signal-to-noise ratio of the PLC signal is relatively high. Figure 6 As shown, the inverter provided in the embodiment of the present application includes: a power conversion circuit 201, a power line communication PLC circuit 202, a first transformer T1 and a second transformer T2.

[0052] The power conversion circuit 201 is used to connect to the power line, which includes a first transmission line L1 and a second transmission line L2. It can be understood that if the power line is connected to the photovoltaic controller 50, the power conversion circuit 201 is used to receive the direct current transmitted by the photovoltaic panel through the power line and convert the direct current into alternating current, that is, the power line is used to transmit direct current. If the power line is connected to the data collector 30, the power conversion circuit 201 is used to convert the direct current provided by the photovoltaic panel into alternating current and then transmit it to the power line, that is, the power line is used to transmit alternating current.

[0053] Continue to refer Figure 6 One end of the primary side (number of turns N1) of the first transformer T1 is connected to one end of the PLC circuit 202, and the secondary side (number of turns N2) of the first transformer T1 is connected in series between the port of the power conversion circuit 201 and the port of the first transmission line L1.

[0054] One end of the primary side (number of turns N1') of the second transformer T2 is connected to the other end of the PLC circuit 202, and the secondary side (number of turns N2') of the second transformer T2 is connected in series between the port of the power conversion circuit 201 and the port of the second transmission line L2. The other end of the primary side of the first transformer T1 is connected to the other end of the primary side of the second transformer T2.

[0055] It is understandable that if the power line is connected to the photovoltaic controller 50, the port of the power conversion circuit 201 mentioned above may refer to a DC input port, that is, a port for receiving DC power. If the power line is connected to the data collector 30, the port of the power conversion circuit 201 mentioned above may refer to an AC output port, that is, a port for outputting AC power.

[0056] It can also be understood that the first transmission line L1 has two ports, one of which is connected to the secondary side of the first transformer T1, and the other is connected to the photovoltaic controller 50 or the data collector 30. The second transmission line L2 also has two ports, one of which is connected to the secondary side of the second transformer T2, and the other is connected to the photovoltaic controller 50 or the data collector 30.

[0057] Combination Figure 6 As can be seen from 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 send or receive PLC signals through the first transmission line L1 and the second transmission line L2 in the power line. Since this coupling method can be coupled with the two transmission lines in the power line respectively, and is coupled with the power line by electromagnetic induction through two transformers, this coupling method belongs to differential magnetic isolation coupling. Based on the coupling method of differential magnetic isolation, the common mode noise in the power line can be effectively suppressed, and the noise generated by the power conversion circuit can be effectively suppressed. As a result, it can be ensured that the PLC circuit is coupled to the PLC signal in the power line, or the signal-to-noise ratio of the PLC signal coupled from the power line is high.

[0058] In summary, the embodiment of the present application provides an inverter, in which a PLC circuit can be coupled to two transmission lines in a power line through a first transformer and a second transformer. Based on this coupling mode, the common mode noise in the power line can be effectively suppressed, and the noise generated by the power conversion circuit can be effectively suppressed, ensuring that the signal-to-noise ratio of the PLC signal is high.

[0059] It is understandable that the number of turns N1 of the primary side of the first transformer T1, the number of turns N2 of the secondary side, and the number of turns N1' of the primary side of the second transformer T2, the number of turns N2' of the secondary side can be flexibly set according to the requirements of the application scenario, and the embodiment of the present application does not limit this. Among them, N1, N2, N1' and N2' can all be integers greater than 1.

[0060] Optionally, the number of turns N1 of the primary side of the first transformer T1 may 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 may 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 sides of the two transformers to be the same, and the number of turns of the secondary sides 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.

[0061] It can be understood that the first transformer T1 can be equivalently formed by the first inductor and the second inductor, and the second transformer T2 can also be equivalently formed by the third inductor and the fourth inductor. Among them, 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.

[0062] Furthermore, the number of turns N1 of the inductor coil of the first inductor may 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 may 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 may be a group of symmetrical inductors, and the second inductor and the fourth inductor may be a group of symmetrical inductors. By setting two groups of symmetrical inductors to couple the PLC signal of the PLC circuit, or coupling 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 offset, 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.

[0063] Optionally, in order to ensure a better suppression effect on common mode noise, the magnetic core of the first transformer T1 and the magnetic core of the second transformer T2 may be the same. The same magnetic core may refer to the same material, shape and size of the magnetic core. For example, the first transformer T1 and the second transformer T2 may be integrated into one device and may share the same magnetic core.

[0064] Optionally, the number of turns of the primary side N1 of the first transformer T1 may be equal to the number of turns N2 of the secondary side of the first transformer T1, and the number of turns N1' of the primary side of the second transformer T2 may 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 may satisfy: N1=N2=N1'=N2'.

[0065] By setting the number of turns of the primary and secondary sides of the two transformers in the inverter 20 to be equal, on the one hand, it can ensure a 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.

[0066] Figure 7 is a schematic diagram of the structure of another inverter provided in an embodiment of the present application. Figure 7 As shown, the PLC circuit 202 may include: a sending circuit 2021 and a receiving circuit 2022. The sending circuit 2021 is used to process the sending signal sent to other devices (such as the data collector 30 or the photovoltaic controller 50), for example, to amplify the power of the sending signal. The receiving circuit 2022 is used to process the receiving signal from other devices, for example, to filter the receiving signal.

[0067] It can be understood that the transmission signal may refer to a PLC signal transmitted to the data collector 30 or the photovoltaic controller 50 via the power line, and the reception signal may refer to a PLC signal received from the data collector 30 or the photovoltaic controller 50 via the power line.

[0068] Optionally, refer to Figure 7 , the output end of the transmitting circuit 2021 is respectively 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, and the input end of the receiving circuit 2022 is respectively 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. That is, the transmitting circuit 2021 and the receiving circuit 2022 can share the primary sides of the two transformers to achieve the coupling of the transmitting signal and the receiving signal. Thus, the increase in the structural complexity of the inverter 20 can be effectively avoided, and the increase in the cost of the inverter can be avoided.

[0069] Figure 8 is a schematic diagram of the structure of another transformer provided in an embodiment of the present application. Figure 8As shown, the primary side of the first transformer T1 may include a first winding (with N1 turns) and a second winding (with N3 turns), and the primary side of the second transformer T2 may include a third winding (with N1' turns) and a fourth winding (with N3' turns). The output end of the transmitting circuit 2021 is respectively connected to one end of the first winding and one end of the third winding, 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 respectively connected to one end of the second winding and one end of the fourth winding, 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 windings, thereby effectively improving the flexibility of PLC signal coupling.

[0070] 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. In addition, 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.

[0071] 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.

[0072] 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.

[0073] If the power line connected to the inverter 20 is used to transmit AC power, the power line can be an AC line, for example, 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 neutral 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 the PLC signal into the phase line and the neutral line, or into the two phase lines.

[0074] Optionally, continue to refer to Figures 6 to 8 The inverter 20 may further include: a capacitor C1; the capacitor C1 may be connected in parallel with a port of the power conversion circuit 201.

[0075] like Figures 6 to 8As shown, 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 called a differential capacitor, a filter capacitor, or an X capacitor. Alternatively, the inverter 20 can include multiple capacitors C1, each capacitor C1 can be connected across a transmission line of the power line and the ground, the capacitor C1 can also be called a Y capacitor, and the multiple Y capacitors can be equivalent to differential capacitors.

[0076] Since the frequency of the PLC signal is relatively high, and the capacitor has the characteristics of passing high frequencies and blocking low frequencies, passing alternating current and isolating direct current, the impedance of the capacitor C1 to the PLC signal is usually less than 0.1 ohms (Ω). As a result, if the PLC circuit 202 directly injects a PLC signal into the power line or extracts a PLC signal, the PLC signal will be short-circuited by the capacitor C1 (that is, the energy of the PLC signal is absorbed by the capacitor C1). Therefore, in an embodiment of the present application, it is necessary to effectively couple the PLC signal to the power line through the first transformer T1 and the second transformer T2, or to couple the PLC signal from the power line to the PLC circuit 202, that is, the effective injection and extraction of the PLC signal can be achieved through two transformers.

[0077] As an optional implementation, the first transformer T1 and the second transformer T2 may be two independent magnetic rings. That is, the first transformer T1 (i.e., the first inductor and the second inductor) may be one magnetic ring, and the second transformer T2 (i.e., the third inductor and the fourth inductor) may be another magnetic ring.

[0078] 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 a board. In addition, the primary and secondary sides of the first transformer, and the primary and secondary sides of the second transformer can be wound on the same magnetic core.

[0079] It is understandable that the inverter provided in the embodiment of the present application may include two groups of communication circuits, each group of communication circuits includes a PLC circuit, a first transformer and a second transformer. Among them, 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.

[0080] In summary, an embodiment of the present application provides an inverter, wherein a power conversion circuit of the inverter is used 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 through a first transformer and a second transformer. Since the PLC circuit is coupled to two transmission lines in the power line through two transformers, the common mode noise in the power line can be effectively suppressed. Furthermore, since the PLC circuit is coupled to the power line by electromagnetic induction through two transformers, the noise generated by the power conversion circuit can be effectively suppressed. It can be seen from this that the inverter provided in the embodiment 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.

[0081] The present application also provides a PLC system, such as Figure 1 As shown, the PLC system includes: a data collector 30, and at least one inverter 20 as provided in the above embodiment, and the data collector 30 is connected to the at least one inverter 20 via a power line. Since the power line is used to transmit alternating current, the PLC system can be called an AC PLC system.

[0082] For example, the PLC system may include a plurality of inverters 20 , and the data collector 30 may be connected to the plurality of inverters 20 via power lines and perform PLC communication with the plurality of inverters 20 .

[0083] The present application also provides another PLC system, such as Figure 2 As shown, the PLC system includes: an inverter 20 as provided in the above embodiment, and at least one photovoltaic controller 50; the inverter 20 is connected to the at least one photovoltaic controller 50 via a power line. Since the power line is used to transmit direct current, the PLC system can be called a direct current PLC system.

[0084] For example, the PLC system may include multiple photovoltaic controllers 50, and the inverter 20 may be connected to the multiple photovoltaic controllers 50 via power lines and perform PLC communication with the multiple photovoltaic controllers 50. The photovoltaic controller 50 may be a photovoltaic optimizer or a photovoltaic shut-off device.

[0085] In the embodiments of the present application, the terms "first", "second" and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The term "at least one" means one or more, and "plurality" means two or more.

[0086] The above is only an optional implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. An inverter, characterized in that: The inverter includes: a power conversion circuit, a power line communication PLC circuit, a first transformer and a second transformer; The power conversion circuit is used to connect to a power line, and the power line includes a first transmission line and a second transmission line; The PLC circuit is used to send or receive a PLC signal via the power line; One end of the primary side of the first transformer is connected to one end of the PLC circuit, and the 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 the primary side of the second transformer is connected to the other end of the PLC circuit, and the secondary side of the second transformer is connected in series between a 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.

2. The inverter according to claim 1, characterized in that: 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 according to claim 2, characterized in that: 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 in that: The PLC circuit includes: a sending circuit and a receiving circuit; The output end of the transmitting circuit is respectively connected to one end of the primary side of the first transformer and one end of the primary side of the second transformer, and the input end of the receiving circuit is respectively connected to one end of the primary side of the first transformer and one end of the primary side of the second transformer.

5. The inverter according to claim 1 or 2, characterized in that: The PLC circuit includes: 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 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 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; 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 in that: 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 neutral 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 in that: The inverter further includes: a capacitor; The capacitor is connected in parallel with a port of the power conversion circuit.

8. The inverter according to any one of claims 1 to 7, characterized in that: 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 in that: The PLC system comprises: a data collector and at least one inverter according to any one of claims 1 to 8; the data collector is connected to at least one inverter via the power line.

10. A PLC system, characterized in that: The PLC system comprises: an inverter as described in any one of claims 1 to 8, and at least one photovoltaic controller; the inverter is connected to the at least one photovoltaic controller via the power line.

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