Power converter and PLC system

Abstract

The invention provides a power converter and a PLC system, and belongs to the field of photovoltaic technology. The power converter provided by the invention comprises N change-over switches, one ends of the N change-over switches are connected with a receiving filter, and the other ends of the N change-over switches are connected with N couplers in a one-to-one correspondence manner. The PLC chip can control the other change-over switches to be switched off in the process that one change-over switch is switched on, so that it is ensured that the receiving filter and the PLC chip only receive and process receiving signals from one coupler each time. Therefore, the noise signals transmitted by other couplers can be effectively prevented from being superposed on the received signals processed by the PLC chip, so that the signal-to-noise ratio of the received signals can be effectively improved, and the reliability of PLC communication is ensured.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and particularly to a power converter and a PLC system. Background Art

[0002] A photovoltaic (PV) power generation system generally includes devices such as photovoltaic panels, a power converter (also known as an inverter), and a box-type transformer (abbreviated as box transformer). Among them, the power converter is used to convert the direct current (DC) output by the photovoltaic panel into alternating current (AC). The box transformer is used to perform voltage conversion on the alternating current output by the inverter.

[0003] A photovoltaic power generation system generally also includes a photovoltaic optimizer, which can 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, and the output ends of multiple photovoltaic optimizers are connected in series to form an optimizer string, and this optimizer string is then connected to the power converter. Among them, the power converter and the photovoltaic optimizers in the optimizer string can communicate through power line communication (PLC) technology to achieve information interaction operations such as service query and command control. The power converter generally includes a PLC chip, a sending circuit, a receiving circuit, and multiple couplers. Among them, the sending circuit is used to process the sending signal output by the PLC chip, and the receiving circuit is used to process the receiving signals from multiple couplers and send the processed receiving signals to the PLC chip. The multiple couplers are used to connect to multiple optimizer strings through power lines.

[0004] Since multiple couplers are all connected to the PLC chip through the receiving circuit, when the PLC chip receives and processes the receiving signal transmitted by any one coupler, the noise signals transmitted by other couplers will also be superimposed on this receiving signal, affecting the signal-to-noise ratio of the receiving signal. Summary of the Invention

[0005] This application provides a power converter and a PLC system, which can solve the technical problem that the superimposition of noise signals of multiple couplers in the PLC system in the related art affects the signal-to-noise ratio of the receiving signal.

[0006] In a first aspect, a power converter is provided. The power converter includes: a PLC chip, a transmitting circuit, a receiving filter, N switching switches, and N couplers, where N is an integer greater than 1. Each of the N couplers is used to connect a plurality of series-connected photovoltaic optimizers, and each photovoltaic optimizer is used to connect to a photovoltaic panel. The PLC chip is respectively connected to the transmitting circuit and the receiving filter. The transmitting circuit is further connected to the N couplers. The receiving filter is further connected to one end of each of the N switching switches, and the other ends of the N switching switches are correspondingly connected to the N couplers. Among them, the PLC chip is used to: output a transmission signal; the transmitting circuit is used to process the transmission signal; each of the N couplers is used to couple the processed transmission signal to a power line and transmit it to a photovoltaic optimizer, and is used to receive a received signal from the photovoltaic optimizer transmitted by the power line. The PLC chip is used to: during the closing process of one of the N switching switches, control all other switching switches among the N switching switches to be turned off. The receiving filter is used to: filter the received signal and transmit the filtered received signal to the PLC chip.

[0007] In the solution provided in this application, since the PLC chip can control all other switching switches to be turned off during the closing process of one switching switch, it can be ensured that the receiving filter and the PLC chip receive and process only the received signal from one coupler each time. Thus, it can effectively avoid the noise signal (such as the noise signal from the DC / DC conversion circuit) transmitted by other couplers from being superimposed on the received signal processed by the PLC chip, thereby effectively improving the signal-to-noise ratio of the received signal.

[0008] Optionally, the correspondence between the plurality of photovoltaic optimizers and the N switching switches is stored in the PLC chip. The transmission signal output by the PLC chip carries the identifier of the target photovoltaic optimizer, and the transmission signal is used to instruct the target photovoltaic optimizer to report the received signal. The PLC chip is used to control the switching switch corresponding to the target photovoltaic optimizer among the N switching switches to be closed based on the correspondence between the plurality of photovoltaic optimizers and the N switching switches during the process of receiving the received signal from the target photovoltaic optimizer.

[0009] Among them, the correspondence can be obtained by the PLC chip through communication with the plurality of photovoltaic optimizers. For example, the PLC chip can control the N switching switches to be closed in sequence, and when each switching switch is closed, receive the identifiers (such as address information) reported by the respective photovoltaic optimizers corresponding to the switching switch. The PLC chip can then store the correspondence between the identifiers reported by the plurality of photovoltaic optimizers and the closed switching switch.

[0010] Optionally, the power converter may further include: a controller configured to control a plurality of photovoltaic optimizers. The PLC chip is further configured to modulate the information sent by the controller (such as a turn-off control instruction, a status query instruction, an upgrade instruction, etc.) to obtain the transmission signal, and to demodulate the received signal and transmit the demodulated received signal to the controller. Among them, the received signal may carry information reported by the photovoltaic optimizer to the controller (such as status information).

[0011] Optionally, the transmission circuit may include: N power amplifiers. The input ends of the N power amplifiers are all connected to the PLC chip, and the output ends of the N power amplifiers are respectively connected to the N couplers in one-to-one correspondence. Each of the N power amplifiers is configured to amplify the power of the transmission signal output by the PLC chip and transmit the transmission signal with amplified power to a corresponding coupler.

[0012] Since N power amplifiers are provided in the transmission circuit, it can be ensured that the power of the transmission signal emitted by each coupler is relatively high, thereby effectively improving the signal-to-noise ratio of the PLC system and ensuring the reliability of the PLC system communication.

[0013] Optionally, the isolation degree between the output ends of the N power amplifiers is greater than a threshold value. That is to say, the isolation degree between the output ends of the N power amplifiers can be relatively large, thereby effectively preventing the noise on one receiving channel from being fed back to other receiving channels through the power amplifier, affecting the independence between the receiving channels and the signal-to-noise ratio of the received signal.

[0014] In a second aspect, another power converter is provided. The power converter includes: N PLC chips, a transmission circuit, N receiving filters, and N couplers, where N is an integer greater than 1. Each of the N couplers is configured to connect a plurality of serially connected photovoltaic optimizers, and each photovoltaic optimizer is configured to connect to a photovoltaic panel. The input ends of the N receiving filters are respectively connected to the N couplers in one-to-one correspondence, and the output ends of the N receiving filters are respectively connected to the N PLC chips in one-to-one correspondence. One of the N PLC chips is a main PLC chip, the main PLC chip is connected to the transmission circuit, and the transmission circuit is further connected to the N couplers. The main PLC chip is configured to: output a transmission signal; the transmission circuit is configured to process the transmission signal. Each of the N couplers is configured to: couple the processed transmission signal to the power line and transmit it to the photovoltaic optimizer, and to receive the received signal from the photovoltaic optimizer transmitted by the power line. Each of the N receiving filters is configured to: receive the received signal transmitted by a corresponding coupler, filter the received signal, and transmit it to a corresponding PLC chip.

[0015] In the power converter provided by the present application, since N receiving filters and N PLC chips are provided, it can be ensured that the received signals transmitted by each coupler can be independently transmitted and processed. Thus, the superposition of noise signals (such as noise signals from the DC / DC conversion circuit) transmitted by other couplers can be effectively avoided, and the signal-to-noise ratio of the received signals is improved.

[0016] Optionally, the power converter may further include: a controller, and the N PLC chips are all connected to the controller. Each of the N PLC chips is configured to demodulate the received signal and transmit the demodulated received signal to the controller. The main PLC chip is further configured to modulate the information sent by the controller to obtain a transmission signal.

[0017] Since the N PLC chips are all connected to the controller and can directly transmit the demodulated received signals to the controller, that is, there is no need for the main PLC chip to converge the received signals and then transmit them to the controller, so the functional design of the main PLC chip can be effectively simplified.

[0018] Optionally, the power converter may further include: a controller, the main PLC chip is connected to the controller and is connected to the other slave PLC chips except the main PLC chip among the N PLC chips. The slave PLC chips are configured to demodulate the received signals and transmit the demodulated received signals to the main PLC chip. The main PLC chip is further configured to demodulate the received signals, transmit the demodulated received signals and the demodulated received signals transmitted by the slave PLC chips to the controller, and is configured to modulate the information sent by the controller to obtain a transmission signal.

[0019] Since the main PLC chip can converge the received signals demodulated by each slave PLC chip and then transmit them to the controller, the controller does not need to communicate with other slave PLC chips anymore, so the functional design of the controller can be effectively simplified.

[0020] Optionally, the transmission circuit may include N power amplifiers. The input ends of the N power amplifiers are all connected to the main PLC chip, and the output ends of the N power amplifiers are respectively connected to the N couplers in one-to-one correspondence. Each of the N power amplifiers is configured to amplify the power of the transmission signal output by the main PLC chip and transmit the transmission signal with amplified power to a corresponding coupler.

[0021] Optionally, the isolation degree between the output ends of the N power amplifiers is greater than a threshold value.

[0022] In a third aspect, a PLC system is provided, which includes: a plurality of photovoltaic optimizers, and a power converter provided as in the first aspect or the second aspect above. Among them, the power converter includes N couplers, each of the N couplers is connected to at least two serially connected photovoltaic optimizers among the plurality of photovoltaic optimizers, and each photovoltaic optimizer is used to connect to a photovoltaic panel, where N is an integer greater than 1.

[0023] In summary, the present application provides a power converter and a PLC system. In the solution provided by the present application, the power converter includes N switching switches, one end of each of the N switching switches is connected to a receiving filter, and the other end is connected to the N couplers in one-to-one correspondence. The PLC chip can control all other switching switches to turn off during the closing process of one of the switching switches, so as to ensure that the receiving filter and the PLC chip only receive and process the receiving signal from one coupler each time. Thus, it is possible to effectively avoid the noise signals transmitted by other couplers from being superimposed on the receiving signal processed by the PLC chip, thereby effectively improving the signal-to-noise ratio of the receiving signal. Description of the Drawings

[0024] Figure 1 is a schematic structural diagram of a PLC system provided by an embodiment of the present application;

[0025] Figure 2 is a schematic structural diagram of another PLC system provided by an embodiment of the present application;

[0026] Figure 3 is a schematic structural diagram of yet another PLC system provided by an embodiment of the present application;

[0027] Figure 4 is a schematic structural diagram of a power converter provided by an embodiment of the present application;

[0028] Figure 5 is a schematic structural diagram of still another PLC system provided by an embodiment of the present application;

[0029] Figure 6 is a schematic structural diagram of another power converter provided by an embodiment of the present application;

[0030] Figure 7 is a schematic structural diagram of yet another power converter provided by an embodiment of the present application. Detailed Embodiments

[0031] The power converter and the PLC system provided by the embodiments of the present application are introduced in detail below with reference to the drawings. First, the key terms related to the embodiments of the present application are introduced.

[0032] Inverter: Also known as a power converter, it is a DC-to-AC power supply used to convert the direct current of a photovoltaic panel into alternating current.

[0033] PV module: photovoltaic panel.

[0034] PV string: Multiple photovoltaic panels are connected in series to form a PV string, and multiple PV strings are connected in parallel to the inverter as DC input.

[0035] String inverter power station: All the photovoltaic modules in the power station are grouped. The DC power generated by each group of photovoltaic modules is converted into AC power through a string inverter, and then the AC power is converged, stepped up, and connected to the grid.

[0036] Box transformer: Abbreviation for box-type transformer, which contains a low-voltage distribution cabinet and a transformer.

[0037] Photovoltaic optimizer: A type of DC-to-DC power supply used to convert the DC power of a photovoltaic panel into adjustable DC power. One photovoltaic optimizer can be connected to one or more photovoltaic panels.

[0038] Optimizer string: Multiple photovoltaic optimizers are connected in series to form an optimizer string, and multiple optimizer strings are connected in parallel to the inverter as DC input.

[0039] Photovoltaic disconnect switch: A switch that can cut off the output of a photovoltaic panel. Generally, one photovoltaic disconnect switch is configured for one photovoltaic panel. In case of danger, it can quickly cut off the connection between photovoltaic panels and reduce the voltage of the PV string.

[0040] MPPT: Real-time detection of the power output (such as voltage and current) of a photovoltaic panel to ensure that the photovoltaic panel operates at the maximum power state.

[0041] Photovoltaic panels are the core components of a photovoltaic power generation system, which are greatly affected by light radiation. In case of shading, the power generation will be significantly reduced. Moreover, since the voltage is very high after photovoltaic panels are connected in series, in case of dangerous situations such as fires, there is a need to have a way to reduce the voltage of the photovoltaic panel string to protect personal safety. Therefore, a photovoltaic disconnect switch is generally also deployed in the photovoltaic power generation system, and this photovoltaic disconnect switch can control the on / off of the output voltage of the photovoltaic panel. Figure 1 It is a schematic structural diagram of a photovoltaic power generation system provided by an embodiment of the present application. As Figure 1As shown, each photovoltaic panel can be connected to a photovoltaic disconnect switch. Multiple photovoltaic disconnect switches can be connected in series to form a string. When the photovoltaic disconnect switch is closed, the voltage of the string is equal to the series voltage of each photovoltaic panel. When the photovoltaic disconnect switch is opened, the voltage of the string is basically equal to 0V. In case of danger, the connection between the photovoltaic panels can be quickly disconnected by controlling the photovoltaic disconnect switch, thereby reducing the voltage of the string. Among them, the power converter communicates with the photovoltaic disconnect switch through PLC technology, and the power converter is the CCO of the PLC system, and the photovoltaic disconnect switch is the STA of the PLC system.

[0042] Reference Figure 1 It can also be seen that the photovoltaic disconnect switch can be replaced by a photovoltaic optimizer, which has the MPPT function and can ensure the maximum output power of the photovoltaic panel. In the photovoltaic power generation system, the DC output of the photovoltaic optimizer or the photovoltaic disconnect switch will be controlled by the power converter to keep the DC bus voltage within a suitable and safe range. Therefore, the reliability of the PLC communication between the power converter and the photovoltaic optimizer or the photovoltaic disconnect switch is particularly important.

[0043] Figure 2 It is a schematic structural diagram of another photovoltaic power generation system provided by an embodiment of the present application. As Figure 1 and Figure 2 shown, the power converter can include a PLC host, multiple couplers, multiple DC / DC (direct current - direct current) conversion circuits, and a DC / AC circuit. Among them, the PLC host is used to communicate with the PLC slave in the photovoltaic optimizer or the photovoltaic disconnect switch to realize the sending and receiving of PLC signals; the multiple couplers are used to be respectively connected to multiple strings (optimizer strings or disconnect switch strings) through power lines; the multiple DC / DC conversion circuits can be used for voltage stabilization and to realize MPPT; the DC / AC circuit is used to convert alternating current into direct current and output it to the power grid. Among them, the PLC host can include a PLC chip, a sending circuit, and a receiving circuit, and the PLC slave can also include a PLC chip, a sending circuit, and a receiving circuit. The PLC chip is used to realize signal modulation and demodulation, the sending circuit is used to process the sending signal (such as amplifying the power of the sending signal), and the receiving circuit is used to process the receiving signal (such as filtering the receiving signal).

[0044] Reference Figure 2, the PLC host 031 is connected to the multiple couplers 032 (such as magnetic rings, inductors or capacitors). The transmission signal sent by the PLC host 031 can be coupled to the power line through the multiple couplers 032, and then transmitted to the PV optimizers or PV disconnectors 02 in multiple strings.

[0045] Such as Figure 2 As shown, taking the power converter 03 connecting 2 strings and using a magnetic ring as the coupler 032 as an example for illustration. When the PLC host 031 sends a signal, the transmission signal can be coupled to the power lines PV1- and PV2- through the magnetic ring 032, and then transmitted to the 2 strings through the power lines respectively. That is to say, the transmission signal will be split into 2 strings. When receiving a signal, the received signals sent by the 2 strings can be coupled to the PLC host 031 through the magnetic ring 032 respectively.

[0046] Referring to Figure 2 It can be known that for the transmission path of PLC signals (including transmission signals and received signals), 2 magnetic rings are equivalent to being in parallel. If the power converter 03 is connected to multiple strings and multiple magnetic rings, inductors or capacitors are used for coupling, for the transmission path of PLC signals, it is equivalent to multiple couplers 032 being in parallel. The parallel connection of the multiple couplers 032 will cause an increase in the loss of PLC signals. For example, when 2 magnetic rings are in parallel, theoretically it will cause the PLC signal to attenuate by half, that is, the intensity of the PLC signal transmitted to each string is theoretically only half of the intensity of the PLC signal sent by the PLC host 031. Correspondingly, when N (N is an integer greater than 1) magnetic rings are in parallel, the intensity of the PLC signal transmitted to each string is theoretically only 1 / N of the original. And, in the scheme of parallel connection of multiple couplers 032 when receiving a signal, as Figure 2 shown, the noise of multiple DC / DC conversion circuits 033 will be superimposed into the receiving channel of the PLC host 031 through the coupler 032, thus seriously affecting the signal-to-noise ratio of the received signal.

[0047] The embodiment of the present application provides a power converter, which can effectively reduce the superposition of noise signals in the receiving channel, thereby effectively improving the signal-to-noise ratio of the PLC system and ensuring the reliability of PLC communication. As Figure 3 And Figure 4 shown, the power converter provided by the embodiment of the present application includes: a PLC chip 10, a transmission circuit 20, a receiving circuit 30, and N couplers 40. Among them, the receiving circuit 30 includes a receiving filter 301 and N switching switches 302. Each of the N couplers 40 is used to connect multiple series-connected PV optimizers, and each PV optimizer is used to connect a PV panel. The structures of the N couplers 40 can be the same. For example, each coupler 40 can include coupling devices such as magnetic rings, inductors and / or capacitors.

[0048] Continue to refer to Figure 3 and Figure 4 The PLC chip 10 is respectively connected to the sending circuit 20 and the receiving filter 301. The sending circuit 20 is also connected to the N couplers 40. One end of each of the N switches 302 in the receiving filter 301 is connected to the N switches 302, and the other ends of the N switches 302 are connected to the N couplers 40 in a one-to-one correspondence.

[0049] The PLC chip 10 is used to output a sending signal. The sending circuit 20 is used to process the sending signal, for example, to amplify the power of the sending signal. Each of the N couplers 40 is used to couple the processed sending signal to the power line and transmit it to the PV optimizer, and is also used to receive the received signal from the PV optimizer transmitted by the power line. Wherein, the sending signal may include a turn-off control instruction, a status query instruction, and / or an upgrade instruction issued by the power converter. The received signal may carry the status information reported by the PV optimizer.

[0050] The PLC chip 10 is configured to: during the closing process of one of the N switches 302, control all other switches among the N switches 302 to be turned off.

[0051] The receiving filter 301 is configured to: filter the received signal and transmit the filtered received signal to the PLC chip 10.

[0052] In the embodiment of the present application, the PLC chip 10 can control only one switch 302 to close each time, so as to ensure that the receiving filter 301 and the PLC chip 10 receive and process the received signals from only one coupler 40 each time. Thereby, it is possible to effectively avoid the noise signals (such as the noise signals from the DC / DC conversion circuit) transmitted by other couplers 40 from being superimposed on the received signals processed by the PLC chip 10, so as to effectively improve the signal-to-noise ratio of the received signals and ensure the reliability of PLC communication.

[0053] Moreover, since the receiving filter 301 and the PLC chip 10 can receive and process the received signals transmitted by different couplers 40 in a time-division manner, so as to achieve isolation of the receiving channels, only one PLC chip 10 needs to be provided in the power converter provided by the embodiment of the present application. Thereby, the circuit design of the power converter is effectively simplified, and further the hardware cost and the structural complexity of the power converter are reduced.

[0054] Optionally, refer to Figure 4, the PLC chip 10 can output control signals to N switching switches 302 to achieve on / off control of the N switching switches. For example, the PLC chip 10 can output control signal 1 to the first switching switch 302 and control signal N to the Nth switching switch 302. Among them, if the control signal output by the PLC chip 10 to a certain switching switch 302 is the first level, then the switching switch 302 can be closed; if the control signal is the second level, then the switching switch 302 can be turned off. The first level can be a high level or a low level relative to the second level, and the embodiments of the present application do not limit this.

[0055] Optionally, each of the N switching switches 302 can include a triode or a metal-oxide-semiconductor field-effect transistor (MOSFET).

[0056] Optionally, the PLC chip 10 can store the corresponding relationships between multiple photovoltaic optimizers and the N switching switches 302. Moreover, the sending signal output by the PLC chip 10 can carry the identifier of the target photovoltaic optimizer, and the sending signal can be used to instruct the target photovoltaic optimizer to report the received signal. Among them, the target photovoltaic optimizer can refer to the photovoltaic optimizer that the controller 50 of the power converter needs to control or the information that needs to be obtained. The identifier of the target photovoltaic optimizer can be the address information of the target photovoltaic optimizer.

[0057] Correspondingly, the PLC chip 10 can be used to control the switching switch 302 corresponding to the target photovoltaic optimizer among the N switching switches to be closed based on the corresponding relationships between the multiple photovoltaic optimizers and the N switching switches 302 during the process of receiving the received signal from the target photovoltaic optimizer.

[0058] It can be understood that the controller 50 in the power converter and the photovoltaic optimizer can communicate based on the master-slave protocol, that is, the controller 50 can first send a sending signal carrying the identifier (such as address information) of the target photovoltaic optimizer to each photovoltaic optimizer connected to the power converter. After the sending circuit 20 sends the sending signal to each photovoltaic optimizer through the N couplers 40, each photovoltaic optimizer can analyze the identifier in the sending signal and match the analyzed identifier with its own identifier. If the match is successful, then the photovoltaic optimizer (i.e., the target photovoltaic device) can report the received signal to the controller 50 in the power converter, such as reporting a received signal carrying status information.

[0059] In the embodiment of the present application, the PLC chip 10 may determine the identifier of the target PV optimizer during the process of modulating the information sent by the controller 50 to generate a transmission signal. Moreover, the PLC chip 10 may determine the switch 302 corresponding to the target PV optimizer based on the identifier of the target PV optimizer and the corresponding relationship between the identifiers of multiple PV optimizers pre-stored in the PLC chip 10 and the N switches 302. After determining that the transmission signal has been completely transmitted, the PLC chip 10 may control the switch 302 corresponding to the target PV optimizer to close and control the other switches 302 to remain in the off state. At this time, the closed switch 302 can transmit the received signal from the target PV optimizer to the receiving filter 301 for filtering by the receiving filter 301 and then transmission to the PLC chip 10.

[0060] It can also be understood that the controller 50 may instruct each PV optimizer to report its status information in a polling manner. For example, the PLC chip 10 may sequentially send transmission signals carrying the identifiers of different PV optimizers, and each PV optimizer may then report the received signal carrying its status information based on the identifier in the transmission signal.

[0061] Exemplarily, referring to Figure 4 , assume that each coupler 40 is connected to two serially-connected PV optimizers. Then, the PLC chip 10 may first output a transmission signal 1, which carries the identifier of the PV optimizer 1 connected to the first coupler 40. After that, the PLC chip 10 may control the first switch 302 connected to the first coupler 40 to close and control the other switches 302 to be turned off, so as to receive the received signal reported by the PV optimizer 1. Further, the PLC chip 10 may output a transmission signal 2, which carries the identifier of the PV optimizer 2 connected to the first coupler 40. After that, the PLC chip 10 can receive the received signal reported by the PV optimizer 2 through the closed first switch 302.

[0062] After obtaining the received signals reported by the two PV optimizers connected to the first coupler 40, the PLC chip 10 can output a transmission signal 3, and the identifier of the PV optimizer 3 connected to the second coupler 40 is carried in the transmission signal 3. Then, the PLC chip 10 can control the second switch 302 connected to the second coupler 40 to close, and control all other switches 302 to turn off, so as to receive the received signal reported by the PV optimizer 3. Further, the PLC chip 10 can output a transmission signal 4, and the identifier of the PV optimizer 4 connected to the second coupler 40 is carried in the transmission signal 4. Then, the PLC chip 10 can receive the received signal reported by the PV optimizer 4 through the closed second switch 302. And so on, the power converter can obtain the received signals of each PV optimizer connected to the N couplers 40 in sequence by sending transmission signals carrying different identifiers.

[0063] Optionally, the correspondence between the identifiers of multiple PV optimizers stored in the PLC chip 10 and the N switches 302 can be manually configured by the operation and maintenance personnel. Or, the PLC chip 10 can first control the N switches 302 to close in sequence, and during the closing process of each switch 302, obtain the identifiers (such as address information) reported by each PV optimizer connected to the switch 302. Then, the PLC chip 10 can generate and store the correspondence between the identifiers reported by each PV optimizer and the closed switch 302.

[0064] Optionally, as Figure 3 and Figure 4 , the transmission circuit 20 in the power converter may include N power amplifiers 201. The input ends of the N power amplifiers 201 are all connected to the PLC chip 10, and the output ends of the N power amplifiers 201 are respectively connected to the N couplers 40 in one-to-one correspondence. The N power amplifiers 201 are used to amplify the power of the transmission signal output by the PLC chip 10 and transmit the transmission signal with amplified power to the corresponding coupler 40. Among them, the power amplifier 201 can also be called a linear driver, abbreviated as line driver.

[0065] It can be understood that the N power amplifiers 201 in the transmission circuit 20 can amplify the power of the same transmission signal output by the PLC chip 10 at the same time. Therefore, the transmission signals output by the N power amplifiers 201 are the same. Correspondingly, the transmission signals transmitted by the N couplers 40 to the N PV strings are the same.

[0066] In the power converter provided by the embodiment of the present application, the transmitting circuit 20 includes N power amplifiers 201 respectively connected to N couplers 40 one by one, which can ensure that the power of the transmission signals sent by each coupler 40 to the photovoltaic optimizer connected thereto is relatively high. Thereby, the signal-to-noise ratio of the PLC system can be effectively improved, and the reliability of the PLC system communication can be ensured.

[0067] Optionally, the isolation degree between the output ends of the N power amplifiers 201 can be greater than a threshold value, that is, the isolation degree between the output ends can be relatively large. For example, the threshold value can be 20 decibels (dB) to 30 dB. Since the input ends of the N power amplifiers 201 are directly connected, by setting a relatively large isolation degree between the output ends of the power amplifiers 201, it is possible to prevent the noise of one receiving channel from being fed back to other receiving channels through the power amplifier 201, affecting the independence of each receiving channel and the signal-to-noise ratio of the received signal.

[0068] For example, during the process that the PLC chip 10 controls the first switching switch 302 to close to receive the received signal transmitted by the first coupler 40, the noise signals on other receiving channels may be fed back to the receiving channel where the first switching switch 302 is located through the power amplifier 201, thereby affecting the signal-to-noise ratio of the received signal transmitted by the first switching switch 302. In the embodiment of the present application, since the isolation degree between the output ends of the power amplifiers 201 is relatively large, effective isolation of the noise signals can be achieved, ensuring that the noise in other receiving channels is not superimposed on each receiving channel, and further effectively improving the signal-to-noise ratio of the received signal.

[0069] Optionally, as Figure 3 shown, the power converter may further include: at least one DC / DC conversion circuit 60 and a DC / AC conversion circuit 70. The at least one DC / DC conversion circuit 60 is connected to the N couplers 40 and is used for voltage conversion of the direct current transmitted by the N couplers 40. The DC / AC conversion circuit 70 is connected to the at least one DC / DC conversion circuit 60 and is used for converting the direct current output by the at least one DC / DC conversion circuit 60 into alternating current and then transmitting it to the power grid.

[0070] Exemplarily, the power converter may include N DC / DC conversion circuits 60, and the N DC / DC conversion circuits 60 may be respectively connected to the N couplers 40 one by one.

[0071] In summary, the embodiments of the present application provide a power converter. The power converter includes N switching switches. One end of the N switching switches is connected to a receiving filter, and the other end is connected to N couplers in one-to-one correspondence. The PLC chip can control all other switching switches to turn off during the closing process of one of the switching switches, so as to ensure that the receiving filter and the PLC chip only receive and process the received signal from one coupler each time. Thus, it is possible to effectively avoid the noise signal transmitted by other couplers from being superimposed on the received signal processed by the PLC chip, thereby effectively improving the signal-to-noise ratio of the received signal.

[0072] The embodiments of the present application also provide another power converter. This power converter can also effectively reduce the superposition of noise signals in the receiving channel, thereby effectively improving the signal-to-noise ratio of the PLC system and ensuring the reliability of PLC communication. As Figure 5 、 Figure 6 and Figure 7 shown, the power converter provided by the embodiments of the present application includes: N PLC chips 10, a transmitting circuit 20, a receiving circuit 30, and N couplers 40. Among them, the receiving circuit 30 includes N receiving filters 301, and N is an integer greater than 1. Each of the N couplers 40 is used to connect a plurality of photovoltaic optimizers connected in series, and each photovoltaic optimizer is used to connect a photovoltaic panel. The structures of the N couplers 40 can be the same. For example, each coupler 40 can include coupling devices such as a magnetic ring, an inductor, or a capacitor.

[0073] Referring to Figure 5 、 Figure 6 and Figure 7 , the input ends of the N receiving filters 301 are connected to the N couplers 40 in one-to-one correspondence, and the output ends of the N receiving filters 301 are connected to the N PLC chips 10 in one-to-one correspondence. One of the N PLC chips 10 is a main PLC chip 10, and the main PLC chip 10 is connected to the transmitting circuit 20, and the transmitting circuit 20 is also connected to the N couplers 40.

[0074] Among them, the main PLC chip 10 is used to output a transmission signal. The transmitting circuit 20 is used to process the transmission signal, for example, to amplify the power of the transmission signal. Each of the N couplers 40 is used to: couple the processed transmission signal to the power line and transmit it to the photovoltaic optimizer, and is used to receive the received signal from the photovoltaic optimizer transmitted by the power line.

[0075] Each of the N receiving filters 301 is used to: receive the received signal transmitted by the corresponding one of the couplers 40, filter the received signal, and then transmit it to the corresponding one of the PLC chips 10. Each PLC chip 10 can then demodulate the received signal.

[0076] In the embodiment of the present application, by providing N independent receiving filters 301 and N independent PLC chips 10, it can be ensured that the received signals transmitted by each coupler 40 can be independently transmitted and processed. That is, each PLC chip 10 and the connected receiving filter 301 will only receive the signals transmitted by one coupler 40, so that the noise signals (such as the noise signals from the DC / DC conversion circuit) transmitted by other couplers 40 can be effectively prevented from being superimposed on the received signals processed by this PLC chip 10. Thereby, the signal-to-noise ratio of the received signals can be effectively improved, and the reliability of PLC communication can be ensured.

[0077] Optionally, continuing to refer to Figure 5 、 Figure 6 and Figure 7 , the power converter may further include: a controller 50, which is used to control each photovoltaic optimizer connected to the power converter. The main PLC chip 10 can be used to modulate the information to be sent to the photovoltaic optimizer sent by the controller 50 to obtain a transmission signal. And each of the N PLC chips 10 is used to demodulate the received received signal for the controller 50 to process the demodulated received signal.

[0078] Based on the above analysis, it can be known that the main PLC chip 10 among the N PLC chips 10 can output a transmission signal, and can receive and process the received signals transmitted by the connected receiving filter 301. Among the N PLC chips 10, the slave PLC chips 10 other than the main PLC chip 10 can receive and process the received signals transmitted by the connected receiving filter 301 without processing the transmission signal.

[0079] As a first possible example, as Figure 7 shown, all of the N PLC chips 10 can be connected to the controller 50, and each of the N PLC chips 10 can directly transmit the demodulated received signal to the controller 50. For example, each PLC chip 10 can transmit the demodulated received signal to the controller 50 through a communication bus such as a CAN bus, an IIC bus, an SPI bus, or an RS485 bus.

[0080] As a second possible example, as Figure 5 and Figure 6 shown, among the N PLC chips 10 included in the PLC chip 10, only the main PLC chip 10 is connected to the controller 50, and the other slave PLC chips 10 are all connected to the main PLC chip 10. For example, the main PLC chip 10 is connected to the controller 50 through a communication bus, and each slave PLC chip 10 is connected to the main PLC chip 10 through a communication bus.

[0081] In this second example, among the N PLC chips 10, each slave PLC chip 10 can be used to transmit the demodulated received signal to the master PLC chip 10. The master PLC chip 10 can then be used to transmit its demodulated received signal, as well as the demodulated received signals transmitted by other slave PLC chips 10, to the controller 50.

[0082] Based on the above two examples, it can be seen that the N PLC chips 10 included in the power converter can directly transmit the demodulated received signal to the controller 50, or alternatively, the master PLC chip 10 can aggregate the signals of each slave PLC chip 10 and then report them to the controller 50 uniformly. For the first example above, since each slave PLC chip 10 can directly communicate with the controller 50 without the need for the master PLC chip 10 to aggregate and forward the signals, the circuit design of the master PLC chip 10 can be effectively simplified. For the second example above, since the master PLC chip 10 can aggregate the signals and then forward them to the controller 50, the controller 50 does not need to communicate with each slave PLC chip 10 separately, thus effectively simplifying the circuit design of the controller.

[0083] Optionally, as Figures 5 to 7 shown, the transmission circuit 20 in the power converter may include N power amplifiers 201. The input ends of the N power amplifiers 201 are all connected to the master PLC chip 10, and the output ends of the N power amplifiers 201 are respectively connected to the N couplers 40 in one-to-one correspondence. The N power amplifiers 201 are used to amplify the power of the transmission signal output by the master PLC chip 10 and transmit the transmission signal with amplified power to the corresponding coupler 40.

[0084] It can be understood that the N power amplifiers 201 in the transmission circuit 20 can simultaneously amplify the power of the same transmission signal output by the master PLC chip 10, so the transmission signals output by the N power amplifiers 201 are the same. Correspondingly, the transmission signals transmitted by the N couplers 40 to the N PV strings are the same.

[0085] In the power converter provided in the embodiment of the present application, the transmission circuit 20 includes N power amplifiers 201 connected to the N couplers 40 in one-to-one correspondence, which can ensure that the power of the transmission signal sent by each coupler 40 to the photovoltaic optimizer connected thereto is relatively high. Thereby, the signal-to-noise ratio of the PLC system can be effectively improved, ensuring the reliability of PLC system communication.

[0086] Optionally, the isolation degree between the output ends of the N power amplifiers 201 can be greater than a threshold value, that is, the isolation degree between each output end can be relatively large. For example, the threshold value can be 20 dB to 30 dB. Since the input ends of the N power amplifiers 201 are directly connected, by setting a relatively large isolation degree between the output ends of each power amplifier 201, the noise of one receiving channel can be prevented from being fed back to other receiving channels through the power amplifier 201, which affects the independence of each receiving channel and the signal-to-noise ratio of the received signal.

[0087] For example, during the process that the PLC chip 10 controls the first switching switch 302 to close to receive the received signal transmitted by the first coupler 40, the noise signals on other receiving channels may be fed back to the receiving channel where the first switching switch 302 is located through the power amplifier 201, thereby affecting the signal-to-noise ratio of the received signal transmitted by the first switching switch 302. In the embodiment of the present application, since the isolation degree between the output ends of each power amplifier 201 is relatively large, effective isolation of the noise signals can be achieved, ensuring that the noise in other receiving channels will not be superimposed on each receiving channel, and further effectively improving the signal-to-noise ratio of the received signal.

[0088] Optionally, as Figure 5 shown, the power converter may further include: at least one DC / DC conversion circuit 60, and a DC / AC conversion circuit 70. The at least one DC / DC conversion circuit 60 is connected to the N couplers 40 and is used for voltage conversion of the direct current transmitted by the N couplers 40. The DC / AC conversion circuit 70 is connected to the at least one DC / DC conversion circuit 60 and is used for converting the direct current output by the at least one DC / DC conversion circuit 60 into alternating current and then transmitting it to the power grid.

[0089] Exemplarily, the power converter may include N DC / DC conversion circuits 60, and the N DC / DC conversion circuits 60 may be connected to the N couplers 40 in one-to-one correspondence.

[0090] In summary, the embodiment of the present application provides a power converter, which includes N PLC chips, and N receiving filters connected to the N PLC chips in one-to-one correspondence. The N receiving filters are also connected to N couplers in one-to-one correspondence. Based on this structural design, it can be ensured that each PLC chip and its connected receiving filter will only receive the signal transmitted by one coupler, thereby effectively preventing the noise signals (such as the noise signals from the DC / DC conversion circuit) transmitted by other couplers from being superimposed on the received signal processed by the PLC chip. Thereby, the signal-to-noise ratio of the PLC system can be effectively improved, and the reliability of the PLC system communication can be ensured.

[0091] The embodiment of the present application also provides a PLC system, as Figure 3 and Figure 5 shown. The PLC system includes: a plurality of photovoltaic optimizers 02, and a power converter 03 provided as in the above example.

[0092] Referring to Figure 3 and Figure 5 , the power converter 03 includes N couplers 40. Each of the N couplers 40 is connected to at least two series-connected photovoltaic optimizers 02 among the plurality of photovoltaic optimizers 02. Each photovoltaic optimizer 02 can be used to connect to a photovoltaic panel 01. Wherein, N is an integer greater than 1.

[0093] It can be understood that the PLC system provided by the embodiment of the present application can be applied to a photovoltaic power station system, for example, it can be applied to a string inverter power station. And, the photovoltaic power station system can include a household power station and an industrial and commercial power station, etc. In addition, the solution provided by the embodiment of the present application can also be applied to other technical fields, such as PLC communication of a multi-machine parallel communication power supply, or PLC communication of an energy storage system, etc.

[0094] The above embodiments are all described by taking the power converter 03 connected to the photovoltaic optimizer 02 as an example. It can also be understood that the power converter 03 provided by the embodiment of the present application can also be connected to a plurality of series-connected photovoltaic disconnectors through the coupler 40, and perform PLC communication with the photovoltaic disconnector based on the solution provided by the above embodiment.

[0095] In the embodiment 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 "a plurality" means two or more.

[0096] The term "and / or" in the present application is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0097] The above is only an alternative embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within 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. A power converter, characterized in that, The power converter includes: a power line communication (PLC) chip, a transmitting circuit, a receiving filter, N switching switches, and N couplers, where N is an integer greater than 1; each of the N couplers is used to connect a plurality of photovoltaic optimizers connected in series, and each photovoltaic optimizer is used to connect to a photovoltaic panel; The PLC chip is respectively connected to the transmitting circuit and the receiving filter. The transmitting circuit is further connected to the N couplers. The receiving filter is further connected to one end of each of the N switching switches, and the other ends of the N switching switches are connected to the N couplers in one-to-one correspondence; The PLC chip is configured to: output a transmission signal; The transmitting circuit is used to process the transmission signal; Each of the N couplers is used to couple the processed transmission signal to the power line and transmit it to the photovoltaic optimizer, and is used to receive the received signal from the photovoltaic optimizer transmitted by the power line; The PLC chip is configured to: during the closing process of one of the N switching switches, control the other N switching switches to be turned off; The receiving filter is used to: filter the received signal and transmit the filtered received signal to the PLC chip.

2. The power converter according to claim 1, characterized in that, The corresponding relationship between the plurality of photovoltaic optimizers and the N switching switches is stored in the PLC chip; The transmission signal output by the PLC chip carries the identifier of the target photovoltaic optimizer, and the transmission signal is used to instruct the target photovoltaic optimizer to report the received signal; The PLC chip is configured to, during the process of receiving the received signal from the target photovoltaic optimizer, based on the corresponding relationship between the plurality of photovoltaic optimizers and the N switching switches, control the switching switch corresponding to the target photovoltaic optimizer among the N switching switches to be closed.

3. The power converter according to claim 1 or 2, characterized in that, The power converter further includes: a controller; The PLC chip is further used to modulate the information sent by the controller to obtain the transmission signal, and is used to demodulate the received received signal and transmit the demodulated received signal to the controller.

4. The power converter according to any one of claims 1 to 3, characterized in that, The transmitting circuit includes: N power amplifiers; The input ends of the N power amplifiers are all connected to the PLC chip. The output ends of the N power amplifiers are connected to the N couplers in one-to-one correspondence. Each of the N power amplifiers is used to amplify the power of the transmission signal output by the PLC chip and transmit the transmission signal with amplified power to a corresponding coupler.

5. The power converter according to claim 4, wherein, The isolation degree between the output ends of the N power amplifiers is greater than a threshold.

6. A power converter, characterized in that, The power converter includes: N PLC chips, a transmitting circuit, N receiving filters, and N couplers, where N is an integer greater than 1; each of the N couplers is used to connect a plurality of photovoltaic optimizers connected in series, and each photovoltaic optimizer is used to connect to a photovoltaic panel; The input ends of the N receiving filters are respectively connected to the N couplers one by one, the output ends of the N receiving filters are respectively connected to the N PLC chips one by one, one of the N PLC chips is a main PLC chip, the main PLC chip is connected to the sending circuit, and the sending circuit is also connected to the N couplers; The main PLC chip is configured to: output a sending signal; The sending circuit is configured to process the sending signal; Each of the N couplers is configured to: couple the processed sending signal to the power line and transmit it to the PV optimizer, and receive the receiving signal from the PV optimizer transmitted by the power line; Each of the N receiving filters is configured to: receive the receiving signal transmitted by a corresponding coupler, and filter the receiving signal and then transmit it to a corresponding PLC chip.

7. The power converter according to claim 6, characterized in that, The power converter further includes: a controller, and the N PLC chips are all connected to the controller; Each of the N PLC chips is configured to demodulate the received receiving signal and transmit the demodulated receiving signal to the controller; The main PLC chip is further configured to modulate the information sent by the controller to obtain the sending signal.

8. The power converter according to claim 6, wherein The power converter further includes: a controller, the main PLC chip is connected to the controller and is also connected to other slave PLC chips among the N PLC chips except the main PLC chip; The slave PLC chip is configured to demodulate the received receiving signal and transmit the demodulated receiving signal to the main PLC chip; The main PLC chip is further configured to demodulate the received receiving signal, transmit the demodulated receiving signal and the demodulated receiving signal transmitted by the slave PLC chip to the controller, and modulate the information sent by the controller to obtain the sending signal.

9. The power converter according to any one of claims 6 to 8, characterized in that, The sending circuit includes N power amplifiers; The input ends of the N power amplifiers are all connected to the main PLC chip, the output ends of the N power amplifiers are respectively connected to the N couplers one by one, and each of the N power amplifiers is configured to amplify the power of the sending signal output by the main PLC chip and transmit the sending signal with amplified power to a corresponding coupler.

10. The power converter according to claim 9, wherein, The isolation degree between the output ends of the N power amplifiers is greater than a threshold value.

11. A PLC system, characterized in that, The PLC system includes: a plurality of PV optimizers, and a power converter as described in any one of claims 1 to 10; The power converter includes N couplers, each of the N couplers is connected to at least two series-connected PV optimizers among the plurality of PV optimizers, and each PV optimizer is used to connect a PV panel, and N is an integer greater than 1.

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