Photovoltaic input port coupling voltage suppression circuit and photovoltaic system

Abstract

The utility model discloses a photovoltaic input port coupling voltage suppression circuit and a photovoltaic system, and belongs to the field of photovoltaic technology. The photovoltaic input port coupling voltage suppression circuit comprises at least two coupling voltage release modules which are respectively arranged corresponding to each path of photovoltaic input port in a photovoltaic inverter; the coupling voltage release module comprises a coupling voltage identification unit and a discharge unit which are connected between the positive input end and the negative input end of the photovoltaic input ports corresponding to the coupling voltage release module. The coupling voltage identification unit is used for outputting a first identification signal when the voltage between the positive input end and the negative input end is lower than a coupling voltage threshold value and outputting a second identification signal when the voltage is higher than a normal voltage threshold value; the normal voltage threshold value is greater than or equal to the coupling voltage threshold value; the discharging unit is used for being switched on according to the first identification signal and switched off according to the second identification signal. According to the embodiment of the utility model, the coupling voltage can be identified and released, and the reliability and safety of a photovoltaic system are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaics, and particularly to a photovoltaic input port coupling voltage suppression circuit and a photovoltaic system. Background Art

[0002] Traditional photovoltaic inverters include multiple photovoltaic input ports. The positive input terminal and the negative input terminal of each photovoltaic input port are connected to the ground through high-impedance sampling resistors, thus forming a high-resistance loop between two independent photovoltaic input ports. When one or several photovoltaic input ports have input voltage (or are powered on), while other photovoltaic input ports have no input voltage, the above input voltage will couple a certain voltage to the photovoltaic input ports without input voltage through the loop formed by the sampling resistors, and the coupling voltage is less than the input voltage.

[0003] In the case where there is a coupling voltage at the photovoltaic input port, the independence requirements of each photovoltaic input port cannot be met, which affects the judgment of the power-on situation of each port by the system control component and the subsequent control process. Moreover, the unpowered photovoltaic input port being charged also poses an electric shock risk to customers. Therefore, the reliability and safety of the existing photovoltaic system are relatively poor. Summary of the Utility Model

[0004] The utility model provides a photovoltaic input port coupling voltage suppression circuit and a photovoltaic system to identify and release the coupling voltage at the photovoltaic input port in the inverter, and improve the reliability and safety of the photovoltaic system.

[0005] In a first aspect, an embodiment of the utility model provides a photovoltaic input port coupling voltage suppression circuit, including:

[0006] At least two coupling voltage release modules, which are respectively arranged corresponding to each photovoltaic input port in the inverter; one path of the photovoltaic input port includes a positive input terminal and a negative input terminal;

[0007] The coupling voltage release module includes:

[0008] A coupling voltage identification unit, which is connected between the positive input terminal and the negative input terminal of the photovoltaic input port corresponding to the coupling voltage release module where it is located; the coupling voltage identification unit is used to output a first identification signal when the voltage between the positive input terminal and the negative input terminal is lower than the coupling voltage threshold value, and output a second identification signal when the voltage between the positive input terminal and the negative input terminal is higher than the normal voltage threshold value; wherein, the normal voltage threshold value is greater than or equal to the coupling voltage threshold value;

[0009] A discharge unit is connected between the positive input terminal and the negative input terminal of the corresponding photovoltaic input port in the coupling voltage release module where it is located; the discharge unit is used to conduct according to the first identification signal and turn off according to the second identification signal.

[0010] Optionally, in the coupling voltage release module, the output terminal of the coupling voltage identification unit is directly connected to the control terminal of the discharge unit;

[0011] Or,

[0012] The photovoltaic input port coupling voltage suppression circuit further includes: a control module, including at least two signal input terminals and at least two signal output terminals respectively corresponding to the at least two signal input terminals; each of the signal input terminals is respectively connected to the output terminal of each of the coupling voltage identification units, and each of the signal output terminals is respectively connected to the control terminal of each of the discharge units; wherein, a corresponding set of signal input terminal and signal output terminal are respectively connected to the coupling voltage identification unit and the discharge unit in the same coupling voltage release module; the control module is used to control the discharge unit receiving the first identification signal to conduct, and control the discharge unit receiving the second identification signal to turn off.

[0013] Optionally, the discharge unit includes: a first transistor and a first resistor; the first transistor and the first resistor are connected in series between the positive input terminal and the negative input terminal of the corresponding photovoltaic input port in the coupling voltage release module where it is located, and the control electrode of the first transistor is connected to the control terminal of the discharge unit.

[0014] Optionally, the normal voltage threshold value is equal to the coupling voltage threshold value; the coupling voltage identification unit includes: a first adjustable precision voltage reference source, a second resistor and a third resistor;

[0015] The cathode of the first adjustable precision voltage reference source is respectively connected to the positive input terminal and the output terminal of the coupling voltage identification unit, the anode of the first adjustable precision voltage reference source is connected to the negative input terminal, the first end of the second resistor is connected to the positive input terminal, the second end of the second resistor is respectively connected to the first end of the third resistor and the reference electrode of the first adjustable precision voltage reference source, and the second end of the third resistor is connected to the negative input terminal; wherein, when the voltage at the second end of the second resistor is equal to the reference voltage of the first adjustable precision voltage reference source, the voltage between the positive input terminal and the negative input terminal is equal to the coupling voltage threshold value.

[0016] Optionally, the coupling voltage identification unit further includes:

[0017] A fourth resistor, connected between the positive input terminal and the cathode of the first adjustable precision voltage reference source;

[0018] and / or, a first voltage stabilizing diode connected between a reference electrode of the first controllable precision voltage stabilizing source and the negative input terminal;

[0019] And / or, a second voltage stabilizing diode is connected between the cathode of the first controllable precision voltage stabilizing source and the negative input terminal.

[0020] Optionally, the coupling voltage identification unit includes: a first voltage stabilizing subunit, a second voltage stabilizing subunit, a self-locking subunit and a discharge control subunit;

[0021] The first end of the first voltage stabilizing subunit is connected to the positive input end, and the second end of the first voltage stabilizing subunit is connected to the first control end of the self-locking subunit; the first voltage stabilizing subunit is configured to be turned on when the voltage between the positive input end and the negative input end is greater than the normal voltage threshold value;

[0022] The first end of the second voltage stabilizing subunit is connected to the positive input end, and the second end of the second voltage stabilizing subunit is connected to the second control end of the self-locking subunit; the second voltage stabilizing subunit is configured to be turned on when the voltage between the positive input end and the negative input end is greater than the coupling voltage threshold value;

[0023] The first input terminal of the self-locking subunit is connected to the positive input terminal, the second input terminal of the self-locking subunit is connected to the negative input terminal, and the output terminal of the self-locking subunit is connected to the first terminal of the discharge control subunit; the self-locking subunit is used to: control the connection between the second input terminal and the output terminal of the self-locking subunit when both the first voltage stabilizing subunit and the second voltage stabilizing subunit are turned on; enter a self-locking state when the first voltage stabilizing subunit is turned off and the second voltage stabilizing subunit is turned on; and release the self-locking state when the second voltage stabilizing subunit is turned off, and control the disconnection between the second input terminal and the output terminal of the self-locking subunit;

[0024] The second end of the discharge control subunit is connected to the positive input end, the third end of the discharge control subunit is connected to the negative input end, and the fourth end of the discharge control subunit is connected to the output end of the coupling voltage identification unit. The discharge control subunit is configured to: when the second input end and the output end of the self-locking subunit are connected, control the connection between the first end and the fourth end of the discharge control subunit so that the coupling voltage identification unit outputs the voltage received by the first end of the discharge control subunit; and when the second input end and the output end of the self-locking subunit are disconnected, control the disconnection between the first end and the fourth end of the discharge control subunit so that the coupling voltage identification unit outputs the voltage received by the second end of the discharge control subunit.

[0025] Optionally, the first voltage stabilizing sub-unit includes: a third zener diode and a first diode; the anode of the first diode is connected to the first end of the first voltage stabilizing sub-unit, the cathode of the first diode is connected to the cathode of the third zener diode, and the anode of the third zener diode is connected to the second end of the first voltage stabilizing sub-unit;

[0026] The second voltage stabilizing sub-unit includes: a second adjustable precision voltage reference source, a fifth resistor, and a sixth resistor; the cathode of the second adjustable precision voltage reference source is respectively connected to the first end of the second voltage stabilizing sub-unit and the first end of the fifth resistor, the reference pole of the second adjustable precision voltage reference source is respectively connected to the second end of the fifth resistor and the first end of the sixth resistor, and the anode of the second adjustable precision voltage reference source is respectively connected to the second end of the second voltage stabilizing sub-unit and the second end of the sixth resistor;

[0027] The self-locking sub-unit includes: a second transistor, a third transistor, a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor; the second transistor is connected between the first control end and the second control end of the self-locking sub-unit, the seventh resistor is connected between the first control end of the self-locking sub-unit and the second input end, the third transistor is connected between the second input end and the output end of the self-locking sub-unit, the eighth resistor is connected between the first input end and the output end of the self-locking sub-unit, the ninth resistor is connected between the control pole of the second transistor and the output end of the self-locking sub-unit, and the tenth resistor is connected between the control pole of the third transistor and the first control end of the self-locking sub-unit;

[0028] The discharge control sub-unit includes: a second diode, a first capacitor, an eleventh resistor, a twelfth resistor, and a thirteenth resistor; the cathode of the second diode is connected to the first end of the discharge control sub-unit, the anode of the second diode is respectively connected to the first end of the first capacitor, the first end of the eleventh resistor, the first end of the twelfth resistor, and the first end of the thirteenth resistor, the second end of the eleventh resistor is connected to the second end of the discharge control sub-unit, the second ends of the first capacitor and the thirteenth resistor are both connected to the third end of the discharge control sub-unit, and the second end of the twelfth resistor is connected to the fourth end of the discharge control sub-unit.

[0029] Optionally, the coupling voltage identification unit includes:

[0030] A sampling sub-unit, the first input end of the sampling sub-unit is connected to the negative input end, and the second input end of the sampling sub-unit is connected to the positive input end; the sampling sub-unit is used for collecting the voltage between the positive input end and the negative input end and converting it into a sampling voltage for output;

[0031] A hysteresis comparator subunit, an input end of the hysteresis comparator subunit is connected to an output end of the sampling subunit, and an output end of the hysteresis comparator subunit is connected to an output end of the coupled voltage identification subunit; the hysteresis comparator subunit is configured to control the coupled voltage identification subunit to output the first identification signal or the second identification signal according to the sampling voltage.

[0032] Optionally, the sampling subunit includes: a first operational amplifier, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, and a second capacitor; the fifteenth resistor is connected between a first input end of the sampling subunit and a negative input end of the first operational amplifier, the sixteenth resistor is connected between a second input end of the sampling subunit and a positive input end of the first operational amplifier, an output end of the first operational amplifier is connected to an output end of the sampling subunit, the fourteenth resistor is connected between the negative input end and the output end of the first operational amplifier, and the second capacitor and the seventeenth resistor are connected in parallel between the positive input end of the first operational amplifier and the ground;

[0033] The hysteresis comparator subunit includes: a second operational amplifier, a third capacitor, a fourth capacitor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a twenty-second resistor, and a twenty-third resistor; the eighteenth resistor is connected between an input end of the hysteresis comparator subunit and a negative input end of the second operational amplifier, the nineteenth resistor and the third capacitor are connected in parallel between the negative input end of the second operational amplifier and the ground, a first end of the twentieth resistor is connected to a first power supply signal, a second end of the twentieth resistor is connected to a positive input end of the second operational amplifier, the fourth capacitor and the twenty-first resistor are connected in parallel between the positive input end of the second operational amplifier and the ground, an output end of the second operational amplifier is connected to an output end of the hysteresis comparator subunit, the twenty-second resistor is connected between the positive input end and the output end of the second operational amplifier, a first end of the twenty-third resistor is connected to a second power supply signal, and a second end of the twenty-third resistor is connected to the output end of the second operational amplifier.

[0034] In a second aspect, an embodiment of the present invention further provides a photovoltaic system, including: an inverter and a photovoltaic input port coupled voltage suppression circuit as provided in any embodiment of the present invention.

[0035] The photovoltaic input port coupling voltage suppression circuit provided by the embodiment of the present utility model provides a discharge solution for suppressing the coupling voltage of the photovoltaic input port. Specifically, in the embodiment of the present utility model, a coupling voltage release module is respectively arranged for each photovoltaic input port; in the coupling voltage release module, the coupling voltage identification unit can judge whether the voltage of the connected photovoltaic input port needs to be discharged according to the coupling voltage threshold value and the normal voltage threshold value. When the voltage between the positive input terminal and the negative input terminal is less than the coupling voltage threshold value, it can be determined that the voltage is the coupling voltage. At this time, the coupling voltage identification unit outputs a first identification signal to control the conduction of the discharge unit, so as to provide a discharge path, enabling the coupling voltage of the photovoltaic input port without power supply to discharge quickly, avoiding the influence of the coupling voltage on the control process of the photovoltaic system and reducing the risk of electric shock to personnel; when the voltage between the positive input terminal and the negative input terminal is greater than the normal voltage threshold value, it can be determined that the voltage is the normal input voltage. At this time, the coupling voltage identification unit outputs a second identification signal to control the disconnection of the discharge unit, without affecting the normal transmission of the input voltage. Therefore, the embodiment of the present utility model can identify and release the coupling voltage of the photovoltaic input port in the inverter, improving the reliability and safety of the photovoltaic system.

[0036] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present utility model, nor is it used to limit the scope of the present utility model. Other features of the present utility model will become easily understood through the following description. Brief Description of the Drawings

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0038] Figure 1 is a schematic diagram of the connection relationship of each photovoltaic input port of the inverter in the related art;

[0039] Figure 2 is a schematic diagram of the structure of a photovoltaic input port coupling voltage suppression circuit provided by the embodiment of the present utility model;

[0040] Figure 3 is a schematic diagram of the structure of another photovoltaic input port coupling voltage suppression circuit provided by the embodiment of the present utility model;

[0041] Figure 4 is a schematic diagram of the structure of a coupling voltage release module provided by the embodiment of the present utility model;

[0042] Figure 5It is a schematic structural diagram of another coupling voltage release module provided by an embodiment of the present utility model;

[0043] Figure 6 It is a schematic structural diagram of yet another coupling voltage release module provided by an embodiment of the present utility model. Detailed implementation manners

[0044] In order to enable those skilled in the art to better understand the solution of the present utility model, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0045] It should be noted that the terms "first", "second", etc. in the description and claims of the present utility model and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present utility model described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion.

[0046] As pointed out in the background art, there may be a coupling voltage at the unpowered photovoltaic input port of the inverter in the related art due to the influence of other powered photovoltaic input ports. The specific analysis is as follows:

[0047] Figure 1 It is a schematic diagram of the connection relationship of each photovoltaic input port of the inverter in the related art. Refer to Figure 1 , the inverter includes multiple photovoltaic input ports, and each photovoltaic input port includes a positive input terminal and a negative input terminal PV-. Figure 1Exemplarily, two photovoltaic input ports are given. Among them, the positive input terminal of the first photovoltaic input port is denoted as PV1+, and the positive input terminal of the second photovoltaic input port is denoted as PV2+; the negative input terminals PV- of each photovoltaic input port are electrically connected to each other. Among them, the positive input terminals and the negative input terminals PV- of each photovoltaic input port are connected to the ground GND through high-impedance sampling resistors R0, so that a high-resistance loop is formed between the two independent photovoltaic input ports. When one or several photovoltaic input ports have input voltages, the voltage sampling circuits of different photovoltaic input ports are all connected to the ground GND through the sampling resistors R0 to form an impedance loop. At this time, the voltage of the powered-on port will couple the voltage to the unpowered port through this impedance network. The above-mentioned coupled voltage can be sampled via the sampling resistor R0 and provided to the control component of the photovoltaic system for processing. For example, it will be shown on the screen of the host computer or the APP of the mobile device that there are coupled voltages on the unpowered photovoltaic input ports. Taking the photovoltaic input port as an energy storage port for connecting photovoltaic modules as an example, both the positive input terminal and the negative input terminal PV- can be grounded with a sampling resistor R0 of megohm level; for example, the first photovoltaic input port has an input voltage U, the second photovoltaic input port has no input voltage but there is a coupled voltage U1, the input voltage U is greater than two hundred volts, and the coupled voltage U1 can reach about one hundred volts. The above-mentioned coupled voltage affects the safety and reliability of the photovoltaic system.

[0048] To solve the above problems, an embodiment of the present invention provides a photovoltaic input port coupled voltage suppression circuit, which can be applied to an inverter in a photovoltaic system, can identify the coupled voltage of the photovoltaic input port in the inverter and discharge it, which is beneficial to improving the reliability and safety of the photovoltaic system. Figure 2 It is a schematic structural diagram of a photovoltaic input port coupled voltage suppression circuit provided by an embodiment of the present invention. Refer to Figure 2 In this photovoltaic input port coupled voltage suppression circuit, it includes: at least two coupled voltage release modules 10, which are respectively arranged corresponding to each photovoltaic input port in the photovoltaic inverter. Among them, one photovoltaic input port includes a positive input terminal PV+ and a negative input terminal PV-, and the negative input terminals PV- of each photovoltaic input port can be electrically connected together; each positive input terminal PV+ and each negative input terminal PV- can be connected to the ground GND through a sampling resistor R0.

[0049] Each coupling voltage release module 10 may include: a coupling voltage recognition unit 110 and a discharge unit 120. The coupling voltage recognition unit 110 is connected between the positive input terminal PV+ and the negative input terminal PV- in the corresponding photovoltaic input port of the coupling voltage release module 10 where it is located. The coupling voltage recognition unit 110 is configured to output a first recognition signal S1 when the voltage between the connected positive input terminal PV+ and negative input terminal PV- is lower than the coupling voltage threshold value, and output a second recognition signal S2 when the voltage between the positive input terminal PV+ and negative input terminal PV- is higher than the normal voltage threshold value. Herein, the voltage between the positive input terminal PV+ and the negative input terminal PV- is the voltage of the photovoltaic input port, hereinafter referred to as the port voltage. Taking the voltage of the negative input terminal PV- as the zero voltage of the ground signal as an example, the port voltage is actually equal to the voltage of the positive input terminal PV+. The normal voltage threshold value is greater than or equal to the coupling voltage threshold value. The discharge unit 120 is connected between the positive input terminal PV+ and the negative input terminal PV- in the corresponding photovoltaic input port of the coupling voltage release module 10 where it is located; the discharge unit 120 is configured to conduct according to the first recognition signal S1 and turn off according to the second recognition signal S2.

[0050] Specifically, the coupling voltage recognition unit 110 may include a first connection end, a second connection end, and an output end; the first connection end of the coupling voltage recognition unit 110 is connected to the positive input terminal PV+, the second connection end is connected to the negative input terminal PV-, and the output end is configured to output the first recognition signal S1 or the second recognition signal S2. The discharge unit 120 may include a control end, an input end, and an output end; the control end of the discharge unit 120 is directly or indirectly connected to the output end of the coupling voltage recognition unit 110, the input end is connected to the positive input terminal PV+, and the output end is connected to the negative input terminal PV-; the discharge unit 120 is configured to control whether the input end and the output end are connected according to the voltage at its control end.

[0051] Among them, the output signal of the coupling voltage recognition unit 110 is used to characterize the type of the port voltage: when the coupling voltage recognition unit 110 outputs the first recognition signal S1, it indicates that the photovoltaic input port receives a coupling voltage that needs to be released. At this time, the discharge unit 120 conducts according to the first recognition signal S1 as a discharge path, so that the coupling voltage is released through the discharge unit 120. Exemplarily, when the discharge unit 120 conducts, it forms a low-impedance discharge path to achieve the rapid release of the coupling voltage. When the coupling voltage recognition unit 110 outputs the second recognition signal S2, it indicates that the photovoltaic input port receives a normal input voltage and does not need to be released. At this time, the discharge unit 120 turns off according to the second recognition signal S2, which is equivalent to cutting off the discharge path, so that the port voltage can be normally transmitted backward, for example, to the DC bus of the inverter and undergo subsequent power conversion processing via the inverter.

[0052] Exemplarily, the normal voltage threshold is equal to the coupled voltage threshold, which is equivalent to configuring only one threshold voltage value in the coupled voltage identification unit 110, mainly used to determine whether the port voltage is a coupled voltage; if the port voltage is less than the threshold value, it is considered a coupled voltage and needs to be released; if the port voltage is greater than the threshold value, it is considered a normal voltage and does not need to be released. Such a setting can simplify the structure of the coupled voltage identification unit 110 and the voltage identification process. Among them, the coupled voltage threshold can be equal to or slightly higher than the upper limit value of the coupled voltage range of the photovoltaic input port, and the coupled voltage range can be obtained through multiple measurements and statistics before the circuit is put into use.

[0053] Alternatively, according to the foregoing analysis, it can be known that the photovoltaic input port without input voltage obtains the coupled voltage through the sampling resistor path. The coupled voltage is less than the input voltage when the photovoltaic input port is normally connected, and there is a certain gap from the normal input voltage. Accordingly, the normal voltage threshold can be set greater than the coupled voltage threshold, so as to realize the hysteresis control of the on-off state of the discharge unit 120 and improve the system stability. Specifically, when the port voltage is less than the coupled voltage threshold, it is determined as the coupled voltage, and the coupled voltage identification unit 110 outputs the first identification signal S1; when the port voltage is greater than the normal voltage threshold, it is determined as the normal voltage, and the coupled voltage identification unit 110 outputs the second identification signal S2; when the port voltage is between the coupled voltage threshold and the normal voltage threshold, the coupled voltage identification unit 110 maintains the output state, that is, the coupled voltage identification unit 110 maintains the output state before the port voltage enters between the coupled voltage threshold and the normal voltage threshold. In other words, the coupled voltage threshold is used as the switching condition for the coupled voltage identification unit 110 to switch from outputting the second identification signal S2 to outputting the first identification signal S1, and the normal voltage threshold is used as the switching condition for the coupled voltage identification unit 110 to switch from outputting the first identification signal S1 to outputting the second identification signal S2. Exemplarily, the normal voltage threshold is equal to or slightly lower than the lower limit value of the normal input voltage range of the photovoltaic input port, and the normal input voltage range can be obtained through multiple measurements and statistics before the circuit is put into use.

[0054] The photovoltaic input port coupling voltage suppression circuit provided by the embodiment of the present utility model provides a discharge scheme for suppressing the coupling voltage of the photovoltaic input port. Specifically, in the embodiment of the present utility model, a coupling voltage release module 10 is respectively arranged for each photovoltaic input port; in the coupling voltage release module 10, the coupling voltage identification unit 110 can judge whether the voltage of the connected photovoltaic input port needs to be discharged according to the coupling voltage threshold value and the normal voltage threshold value. When the voltage between the positive input terminal PV+ and the negative input terminal PV- is less than the coupling voltage threshold value, it can be determined that the voltage is the coupling voltage. At this time, the coupling voltage identification unit 110 outputs a first identification signal S1 to control the conduction of the discharge unit 120, so as to provide a discharge path, enabling the coupling voltage of the photovoltaic input port without power supply to be quickly discharged, avoiding the influence of the coupling voltage on the control process of the photovoltaic system and reducing the risk of electric shock to personnel; when the voltage between the positive input terminal PV+ and the negative input terminal PV- is greater than the normal voltage threshold value, it can be determined that the voltage is the normal input voltage. At this time, the coupling voltage identification unit 110 outputs a second identification signal S2 to control the disconnection of the discharge unit 120, without affecting the normal transmission of the input voltage. Therefore, the embodiment of the present utility model can identify and release the coupling voltage of the photovoltaic input port in the inverter, improving the reliability and safety of the photovoltaic system.

[0055] On the basis of the above embodiments, optionally, in the coupling voltage release module 10, there are various connection relationships between the coupling voltage identification unit 110 and the discharge unit 120, and several of them will be described below.

[0056] See Figure 2 , in an embodiment, optionally, the output terminal of the coupling voltage identification unit 110 can be directly connected to the control terminal of the discharge unit 120 to simplify the circuit structure. Among them, the voltage of the first identification signal S1 is the conduction voltage of the discharge unit 120, and the voltage of the second identification signal S2 is the cut-off voltage of the discharge unit 120.

[0057] Figure 3 is a schematic structural diagram of another photovoltaic input port coupling voltage suppression circuit provided by the embodiment of the present utility model. See Figure 3, in another embodiment, optionally, the photovoltaic input port coupled voltage suppression circuit further includes: a control module 20, and the control ends of the discharge units 120 are connected to the output end of the coupled voltage identification unit 110 through the control module 20. Specifically, the control module 20 includes at least two signal input terminals IN, and at least two signal output terminals OUT corresponding to the at least two signal input terminals IN respectively; each signal input terminal IN is connected to the output end of each coupled voltage identification unit 110, and each signal output terminal OUT is connected to the control end of each discharge unit 120. Among them, a corresponding set of signal input terminal IN and signal output terminal OUT are respectively connected to the coupled voltage identification unit 110 and the discharge unit 120 in the same coupled voltage release module 10. The control module 20 is used to control the discharge unit 120 receiving the first identification signal S1 to conduct, and to control the discharge unit 120 receiving the second identification signal S2 to turn off. Specifically, the control module 20 is used to control the discharge unit 120 connected to the signal output terminal OUT corresponding to the signal input terminal IN receiving the first identification signal S1 to conduct, and to control the discharge unit 120 connected to the signal output terminal OUT corresponding to the signal input terminal IN receiving the second identification signal S2 to turn off.

[0058] Among them, the output signals of the coupled voltage identification units 110 are gathered in the control module 20. For the same set of signal input terminal IN and signal output terminal OUT, the control module 20 controls the voltage of the discharge control signal DischargeCtr output by the signal output terminal OUT according to the voltage control signal received by the signal input terminal IN. For example, the control module 20 converts the output signal of the coupled voltage identification unit 110 into a voltage capable of driving the discharge unit 120 to turn on and off. Specifically, it controls the discharge control signal DischargeCtr to be the conduction voltage of the discharge unit 120 according to the first identification signal S1, and controls the discharge control signal DischargeCtr to be the cut-off voltage of the discharge unit 120 according to the second identification signal S2. Exemplarily, the control module 20 may include a Digital Signal Processor (DSP) or a Complex Programmable Logic Device (CPLD). This embodiment is applicable, for example, to the case where the voltage of the output signal of the coupled voltage identification unit 110 is outside the driving voltage range of the discharge unit 120. By setting the control module 20, the discharge units 120 can be uniformly managed, and the limitation on the voltage range of the output signal of the coupled voltage identification unit 110 can be reduced, improving the flexibility of the circuit setting of the coupled voltage identification unit 110.

[0059] In the above embodiments, the basic function of the coupling voltage release module 10 in the photovoltaic input port coupling voltage suppression circuit is explained by way of example. There are various specific circuit structures of the coupling voltage release module 10. First, the specific structure of the discharge unit 120 will be described below, and then the structure of the coupling voltage identification unit 110 will be described, but it is not intended to limit the present invention.

[0060] Figure 4 It is a schematic structural diagram of a coupling voltage release module provided by an embodiment of the present invention. Figure 5 It is a schematic structural diagram of another coupling voltage release module provided by an embodiment of the present invention. Figure 6 It is a schematic structural diagram of yet another coupling voltage release module provided by an embodiment of the present invention. Refer to Figures 4 - 6 In one embodiment, optionally, the discharge unit 120 includes: a first transistor Q1 and a first resistor R1; the first transistor Q1 and the first resistor R1 are connected in series between the positive input terminal PV+ and the negative input terminal PV- in the corresponding photovoltaic input port of the coupling voltage release module 10, and the control electrode of the first transistor Q1 is connected to the control terminal of the discharge unit 120. Exemplarily, the first end of the first resistor R1 is connected to the positive input terminal PV+, the second end of the first resistor R1 is connected to the first pole of the first transistor Q1, and the second pole of the first transistor Q1 is connected to the negative input terminal PV-. The control electrode of the first transistor Q1 can be directly connected to the output terminal of the coupling voltage identification unit 110, or connected to the signal output terminal OUT of the control module 20. Specifically, the control module 20 can be selected to be set or not set according to actual needs, and it is not limited here. Among them, the first transistor Q1 is a controllable switch tube, such as a MOSFET switch tube, specifically an NMOS tube. The first resistor R1 can be a resistor with low impedance to provide a low-impedance discharge path when the first transistor Q1 is turned on. Among them, the resistance value of the first resistor R1 can be set by comprehensively considering the port discharge rate and the voltage tolerance of the first transistor Q1. For example, on the basis of ensuring the safety of the first transistor Q1, the impedance of the first resistor R1 is set as small as possible. When the first transistor Q1 is turned off, it is equivalent to cutting off the discharge path. For the convenience of explanation, hereinafter, the first transistor Q1 is an NMOS tube, the conduction voltage of the discharge unit 120 is a high voltage, the cut-off voltage is a low voltage, and the voltage of the first identification signal S1 is higher than the voltage of the second identification signal S2 as an example for explanation.

[0061] Continue to refer to Figure 4, in one embodiment, optionally, the coupling voltage identification unit 110 includes: a first precision voltage regulator T1, a second resistor R2, and a third resistor R3. The specific connection relationship between the components in the coupling voltage identification unit 110 and the photovoltaic input interface corresponding to the coupling voltage identification unit 110 is as follows: the cathode of the first precision voltage regulator T1 is respectively connected to the positive input terminal PV+ and the output terminal of the coupling voltage identification unit 110, the anode of the first precision voltage regulator T1 is connected to the negative input terminal PV-, the first end of the second resistor R2 is connected to the positive input terminal PV+, the second end of the second resistor R2 is respectively connected to the first end of the third resistor R3 and the reference pole of the first precision voltage regulator, and the second end of the third resistor R3 is connected to the negative input terminal PV-.

[0062] Among them, this structure is applicable to the case where the normal voltage threshold is equal to the coupling voltage threshold. The coupling voltage threshold can be adjusted by reasonably configuring the voltages of the second resistor R2 and the third resistor R3, and the reference voltage of the first precision voltage regulator T1, so that when the voltage at the second end of the second resistor R2 is equal to the reference voltage of the first precision voltage regulator T1, the voltage between the positive input terminal PV+ and the negative input terminal PV- is equal to the coupling voltage threshold.

[0063] The working principle of the coupling voltage identification unit 110 is as follows: the voltage identification of the port is realized through the first precision voltage regulator T1. Among them, the second resistor R2 and the third resistor R3 are used for voltage division. Under the condition that the reference voltage of the first precision voltage regulator T1 remains unchanged, changing the resistance ratio relationship between the second resistor R2 and the third resistor R3 can change the coupling voltage threshold. Denote the reference voltage of the first precision voltage regulator T1 as Vref, then the coupling voltage threshold (denoted as Uon) is: Uon = Vref * (R2 + R3) / R3. When the port voltage is lower than the coupling voltage threshold Uon, the first precision voltage regulator T1 is not turned on, so that the voltage of the positive input terminal PV+ is output as the first identification signal S1 through the coupling voltage identification unit 110. The voltage across the control pole and the second pole of the first transistor Q1 reaches its turn-on threshold voltage (or conduction voltage), causing the first transistor Q1 to turn on. The coupling voltage of the photovoltaic input port will discharge along the low-impedance path of the first resistor R1, the first transistor Q1 to the negative input terminal PV- until the coupling voltage of the photovoltaic input port is emptied. At this time, except for the energized photovoltaic input port being charged, the coupling voltages of other photovoltaic input ports are all discharged to 0V. When the port voltage is higher than the coupling voltage threshold Uon, the first precision voltage regulator T1 is turned on, so that the coupling voltage identification unit 110 outputs a low voltage as the second identification signal S2 to control the first transistor Q1 to turn off.

[0064] It can be understood that Figure 4Exemplarily, the cathode of the first controllable precision voltage regulator T1 is directly connected to the control electrode of the first transistor Q1, which is equivalent to the output terminal of the coupling voltage recognition unit 110 being directly connected to the control terminal of the discharge unit 120, but this is not a limitation to the present invention. In other embodiments, the cathode of the first controllable precision voltage regulator T1 can also be connected to the control electrode of the first transistor Q1 through the control module 20; the control module 20 controls the on / off state of the first transistor Q1 according to the cathode signal of the first controllable precision voltage regulator T1.

[0065] Continue to refer to Figure 4 , further, the coupling voltage recognition unit 110 may further include: a fourth resistor R4, connected between the positive input terminal PV+ and the cathode of the first controllable precision voltage regulator T1, serving as a current-limiting resistor to prevent the photovoltaic input port from overvoltage and causing the first controllable precision voltage regulator T1 to break down.

[0066] And / or, the coupling voltage recognition unit 110 may further include: a first zener diode ZD1, connected between the reference electrode of the first controllable precision voltage regulator T1 and the negative input terminal PV-, for protecting the first controllable precision voltage regulator T1. When there is a high voltage higher than the regulated voltage value of the first zener diode ZD1 input at the photovoltaic input port, the voltage of the reference electrode of the first controllable precision voltage regulator T1 is clamped to the regulated voltage value of the first zener diode ZD1, so that the voltage of the reference electrode of the first controllable precision voltage regulator T1 will not be too high to burn out the first controllable precision voltage regulator T1. Among them, the cathode of the first zener diode ZD1 is connected to the reference electrode of the first controllable precision voltage regulator T1, the anode is connected to the negative input terminal PV-, and the regulated voltage value of the first zener diode ZD1 is greater than the reference voltage of the first controllable precision voltage regulator T1.

[0067] And / or, the coupling voltage recognition unit 110 may further include: a second zener diode ZD2, connected between the cathode of the first controllable precision voltage regulator T1 and the negative input terminal PV-. When the coupling voltage recognition unit 110 outputs a high voltage higher than the regulated voltage value of the second zener diode ZD2, the second zener diode ZD2 can clamp the voltage difference between the control electrode and the second electrode of the first transistor Q1 to the regulated voltage value of the second zener diode ZD2, ensuring the stable turn-on of the first transistor Q1. Among them, the cathode of the second zener diode ZD2 is connected to the control electrode of the first transistor Q1, the anode is connected to the negative input terminal PV-, and the regulated voltage value of the second zener diode ZD2 is greater than the turn-on voltage of the first transistor Q1.

[0068] Figure 5 is a schematic structural diagram of another coupling voltage release module provided by an embodiment of the present invention. Refer to Figure 5In another embodiment, optionally, the coupling voltage identification unit 110 includes: a first voltage stabilization subunit 111 , a second voltage stabilization subunit 112 , a self-locking subunit 113 and a discharge control subunit 114 .

[0069] A first terminal of the first voltage stabilizing subunit 111 is connected to the positive input terminal PV+, and a second terminal of the first voltage stabilizing subunit 111 is connected to the first control terminal of the self-locking subunit 113. The first voltage stabilizing subunit 111 is configured to conduct when the voltage between the positive input terminal PV+ and the negative input terminal PV- is greater than a normal voltage threshold, and to shut down otherwise. A first terminal of the second voltage stabilizing subunit 112 is connected to the positive input terminal PV+, and a second terminal of the second voltage stabilizing subunit 112 is connected to the second control terminal of the self-locking subunit 113. The second voltage stabilizing subunit 112 is configured to conduct when the voltage between the positive input terminal PV+ and the negative input terminal PV- is greater than a coupling voltage threshold, and to shut down otherwise. The first input terminal of the self-locking subunit 113 is connected to the positive input terminal PV+, the second input terminal of the self-locking subunit 113 is connected to the negative input terminal PV-, and the output terminal of the self-locking subunit 113 is connected to the first terminal of the discharge control subunit 114. The self-locking subunit 113 is configured to: control the conduction between the second input terminal and the output terminal of the self-locking subunit 113 when both the first voltage stabilizing subunit 111 and the second voltage stabilizing subunit 112 are on; enter a self-locking state when the first voltage stabilizing subunit 111 is off and the second voltage stabilizing subunit 112 is on, maintaining conduction between the second input terminal and the output terminal of the self-locking subunit 113; and release the self-locking state when the second voltage stabilizing subunit 112 is off, controlling the disconnection between the second input terminal and the output terminal of the self-locking subunit 113. The second terminal of the discharge control subunit 114 is connected to the positive input terminal PV+, the third terminal of the discharge control subunit 114 is connected to the negative input terminal PV-, and the fourth terminal of the discharge control subunit 114 is connected to the output terminal of the coupling voltage identification unit 110. The discharge control subunit 114 is configured to: when the second input terminal and the output terminal of the self-locking subunit 113 are connected, control the connection between the first terminal and the fourth terminal of the discharge control subunit 114, so that the coupling voltage identification unit 110 outputs the voltage received by the first terminal of the discharge control subunit 114 as the second identification signal S2; and when the second input terminal and the output terminal of the self-locking subunit 113 are disconnected, control the disconnection between the first terminal and the fourth terminal of the discharge control subunit 114, so that the coupling voltage identification unit 110 outputs the voltage received by the second terminal of the discharge control subunit 114 as the first identification signal S1.

[0070] The coupling voltage threshold value may be defined by the internal structure of the second voltage stabilizing subunit 112 , and the normal voltage threshold value may be defined by the internal structure of the first voltage stabilizing subunit 111 . The two threshold values may be set to be equal or unequal, depending on actual needs.

[0071] It is understandable that Figure 5Exemplarily, the fourth terminal of the discharge control subunit 114 is directly connected to the control electrode of the first transistor Q1, which is equivalent to the output terminal of the coupling voltage identification unit 110 being directly connected to the control terminal of the discharge unit 120, but this is not a limitation on the present utility model. In other embodiments, the fourth terminal of the discharge control subunit 114 can also be connected to the control electrode of the first transistor Q1 through a control module 20; the control module 20 controls the on / off state of the first transistor Q1 according to the potential of the fourth terminal of the discharge control subunit 114.

[0072] Specifically, referring to Figure 5 , the specific structure of the coupling voltage identification unit 110 can be set as follows:

[0073] The first voltage stabilizing subunit 111 includes: a third voltage stabilizing diode ZD3 and a first diode D1; the anode of the first diode D1 is connected to the first terminal of the first voltage stabilizing subunit 111, the cathode of the first diode D1 is connected to the cathode of the third voltage stabilizing diode ZD3, and the anode of the third voltage stabilizing diode ZD3 is connected to the second terminal of the first voltage stabilizing subunit 111. The voltage stabilizing value of the third voltage stabilizing diode ZD3 corresponds to the normal voltage threshold value.

[0074] The second voltage stabilizing subunit 112 includes: a second precision voltage regulator T2, a fifth resistor R5, and a sixth resistor R6; the cathode of the second precision voltage regulator T2 is respectively connected to the first terminal of the second voltage stabilizing subunit 112 and the first terminal of the fifth resistor R5, the reference electrode of the second precision voltage regulator T2 is respectively connected to the second terminal of the fifth resistor R5 and the first terminal of the sixth resistor R6, and the anode of the second precision voltage regulator T2 is respectively connected to the second terminal of the second voltage stabilizing subunit 112 and the second terminal of the sixth resistor R6.

[0075] The self-locking subunit 113 includes: a second transistor Q2, a third transistor Q3, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10; the second transistor Q2 is connected between the first control terminal and the second control terminal of the self-locking subunit 113, the seventh resistor R7 is connected between the first control terminal and the second input terminal of the self-locking subunit 113, the third transistor Q3 is connected between the second input terminal and the output terminal of the self-locking subunit 113, the eighth resistor R8 is connected between the first input terminal and the output terminal of the self-locking subunit 113, the ninth resistor R9 is connected between the control electrode of the second transistor Q2 and the output terminal of the self-locking subunit 113, and the tenth resistor R10 is connected between the control electrode of the third transistor Q3 and the first control terminal of the self-locking subunit 113. Among them, the second transistor Q2 can be a PNP type triode, and the third transistor Q3 can be an NPN type triode. The voltage division between the sum of the resistances of the sixth resistor R6 and the seventh resistor R7 and the fifth resistor R5, in cooperation with the reference voltage of the second precision voltage regulator T2, can be used to define the coupling voltage threshold value.

[0076] The discharge control sub-unit 114 includes: a second diode D2, a first capacitor C1, an eleventh resistor R11, a twelfth resistor R12, and a thirteenth resistor R13; the cathode of the second diode D2 is connected to the first end of the discharge control sub-unit 114, and the anode of the second diode D2 is respectively connected to the first end of the first capacitor C1, the first end of the eleventh resistor R11, the first end of the twelfth resistor R12, and the first end of the thirteenth resistor R13. The second end of the eleventh resistor R11 is connected to the second end of the discharge control sub-unit 114, and the second ends of the first capacitor C1 and the thirteenth resistor R13 are both connected to the third end of the discharge control sub-unit 114. The second end of the twelfth resistor R12 is connected to the fourth end of the discharge control sub-unit 114. Among them, the second diode D2 has the function of preventing reverse connection; the twelfth resistor R12 can be used as a current-limiting resistor for the control electrode of the first transistor Q1, and the first capacitor C1 and the twelfth resistor R12 can form an RC filter; the thirteenth resistor R13 can be used as a charging protection resistor for the first capacitor C1, and the first capacitor C1 is protected from being damaged by too high a port voltage through voltage division with the eleventh resistor R11.

[0077] Taking the case where the coupling voltage threshold value is less than the normal voltage threshold value as an example, the working principle of the coupling voltage recognition unit 110 is as follows:

[0078] When the port voltage is greater than the normal voltage threshold value, the port voltage is greater than the regulated voltage value of the third zener diode ZD3, the voltage across the seventh resistor R7 satisfies the conduction condition of the third transistor Q3, the third transistor Q3 conducts, and at this time, the control electrode voltage of the second transistor Q2 is a low voltage, and the second transistor Q2 conducts. At this time, the cathode voltage of the second diode D2 is pulled down, the voltage across the first capacitor C1 is 0V, which cannot reach the conduction voltage of the first transistor Q1, so the first transistor Q1 is turned off, and the discharge path is cut off and does not work.

[0079] When the port voltage is between the coupling voltage threshold value and the normal voltage threshold value, the port voltage is less than the regulated voltage value of the third zener diode ZD3, but the voltage across the sixth resistor R6 is greater than the reference voltage of the second programmable precision voltage source T2, the self-locking sub-unit 113 is in the self-locking state, and both the second transistor Q2 and the third transistor Q3 remain conducting. At this time, the cathode of the second diode D2 is still at a low voltage, and the first transistor Q1 is still turned off.

[0080] When the port voltage is less than the coupling voltage threshold value, the voltage across the sixth resistor R6 is less than the reference voltage of the second precision voltage regulator T2. The second precision voltage regulator T2 is turned off, causing the self-locking unit 113 to exit the locked state. The second transistor Q2 and the third transistor Q3 are both turned off. At this time, the cathode of the second diode D2 is at a high voltage, and the second diode D2 is equivalent to being turned off. Therefore, the positive input terminal PV+ charges the first capacitor C1 through the eleventh resistor R11. When the voltage across the first capacitor C1 reaches the conduction voltage of the first transistor Q1, the first transistor Q1 conducts to discharge.

[0081] Figure 6 It is a schematic structural diagram of another coupling voltage release module provided by an embodiment of the present invention. Refer to Figure 6 In another embodiment, optionally, the coupling voltage identification unit 110 includes a sampling sub-unit 115 and a hysteresis comparison sub-unit 116. The first input terminal of the sampling sub-unit 115 is connected to the negative input terminal PV-, and the second input terminal of the sampling sub-unit 115 is connected to the positive input terminal PV+. The sampling sub-unit 115 is configured to collect the voltage between the positive input terminal PV+ and the negative input terminal PV- and convert it into a sampling voltage Vpv for output. The input terminal of the hysteresis comparison sub-unit 116 is connected to the output terminal of the sampling sub-unit 115, and the output terminal of the hysteresis comparison sub-unit 116 is connected to the output terminal of the coupling voltage identification unit 110. The hysteresis comparison sub-unit 116 is configured to control the coupling voltage identification unit 110 to output a first identification signal S1 or a second identification signal S2 according to the sampling voltage Vpv.

[0082] Among them, the hysteresis comparison sub-unit 116 can adopt a hysteresis comparator to achieve hysteresis control, so that the circuit is applicable to the case where the normal voltage threshold value is greater than the coupling voltage threshold value. The hysteresis comparison sub-unit 116 can form a high hysteresis value according to the first identification signal S1 and form a low hysteresis value according to the first identification signal S2. The output terminal of the hysteresis comparison sub-unit 116 can be connected to the signal input terminal IN of the control module 20, and the signal output terminal OUT of the control module 20 is connected to the control electrode of the first transistor Q1. The principle of this circuit is as follows:

[0083] When the port voltage is lower than the coupling voltage threshold value, the voltage value obtained after the internal processing (such as voltage division) of the sampling voltage Vpv by the hysteresis comparison sub-unit 116 is lower than the low hysteresis value. The hysteresis comparison sub-unit 116 outputs the first identification signal S1, for example, a high voltage. The control module 20 controls the discharge control signal DischargeCtr to be a high voltage according to the first identification signal S1 to control the first transistor Q1 to conduct, and the discharge path conducts to start discharging.

[0084] When the port voltage is higher than the normal voltage threshold, the voltage value obtained after the internal processing (such as voltage division) of the sampling voltage Vpv by the hysteresis comparator unit 116 is higher than the high hysteresis value UH, and the hysteresis comparator unit 116 outputs a second identification signal S2, for example, a low voltage; the control module 20 controls the discharge control signal DischargeCtr to be a low voltage according to the second identification signal S2 to control the first transistor Q1 to turn off and cut off the discharge path to maintain the port voltage.

[0085] When the port voltage is between the coupling voltage threshold and the normal voltage threshold, the voltage value obtained after the internal processing (such as voltage division) of the sampling voltage Vpv by the hysteresis comparator unit 116 is between the low hysteresis value and the high hysteresis value, and the hysteresis comparator unit 116 maintains its output state.

[0086] It can be understood that Figure 6 exemplarily shows that the output terminal of the hysteresis comparator unit 116 is connected to the control electrode of the first transistor Q1 through the control module 20, but it is not a limitation to the present invention. In other embodiments, the output terminal of the hysteresis comparator unit 116 can also be directly connected to the control electrode of the first transistor Q1; the on-off state of the first transistor Q1 is directly controlled by the output signal of the hysteresis comparator unit 116.

[0087] Specifically, referring to Figure 6 the specific structure of the coupling voltage identification unit 110 can be set as follows:

[0088] The sampling sub-unit 115 includes: a first operational amplifier U1, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, and a second capacitor C2; the fifteenth resistor R15 is connected between the first input terminal of the sampling sub-unit 115 and the negative input terminal of the first operational amplifier U1, the sixteenth resistor R16 is connected between the second input terminal of the sampling sub-unit 115 and the positive input terminal of the first operational amplifier U1, the output terminal of the first operational amplifier U1 is connected to the output terminal of the sampling sub-unit 115, the fourteenth resistor R14 is connected between the negative input terminal and the output terminal of the first operational amplifier U1, and the second capacitor C2 and the seventeenth resistor R17 are connected in parallel between the positive input terminal of the first operational amplifier U1 and the ground. Among them, the fifteenth resistor R15 is a sampling resistor, and the fourteenth resistor R14 is a feedback resistor, which cooperate with the fifteenth resistor R15 to form a negative feedback circuit. Through the first operational amplifier U1, the magnitude of the collected voltage is amplified to obtain the sampling voltage Vpv; the second capacitor C2 is a filtering capacitor, which mainly filters out the high-frequency ripple of the positive input terminal PV+; the sixteenth resistor R16 and the seventeenth resistor R17 are voltage-dividing resistors, and the voltage of the positive input terminal PV+ is voltage-divided and then transmitted to the negative input terminal of the first operational amplifier U1 through the virtual short characteristic of the operational amplifier. The first operational amplifier U1 is powered by, for example, ±8V power supply.

[0089] The hysteresis comparator sub-unit 116 includes: a second operational amplifier U2, a third capacitor C3, a fourth capacitor C4, an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21, a twenty-second resistor R22, and a twenty-third resistor R23; the eighteenth resistor R18 is connected between the input end of the hysteresis comparator sub-unit 116 and the negative input end of the second operational amplifier U2, the nineteenth resistor R19 and the third capacitor C3 are connected in parallel between the negative input end of the second operational amplifier U2 and the ground, the first end of the twentieth resistor R20 is connected to the first power supply signal, the second end of the twentieth resistor R20 is connected to the positive input end of the second operational amplifier U2, the fourth capacitor C4 and the twenty-first resistor R21 are connected in parallel between the positive input end of the second operational amplifier U2 and the ground, the output end of the second operational amplifier U2 is connected to the output end of the hysteresis comparator sub-unit 116, the twenty-second resistor R22 is connected between the positive input end and the output end of the second operational amplifier U2, the first end of the twenty-third resistor R23 is connected to the second power supply signal, and the second end of the twenty-third resistor R23 is connected to the output end of the second operational amplifier U2. Among them, the voltage provided by the first power supply signal is, for example, 3V, the voltage provided by the second power supply signal is, for example, 5V, and the second operational amplifier U2 is powered by a 5V power supply. The second operational amplifier U2 serves as a comparator, and outputs a high voltage when the voltage at its positive input end is greater than the voltage at its negative input end, and outputs a low voltage otherwise; the eighteenth resistor R18 and the nineteenth resistor R19 are voltage-dividing resistors, which divide the sampled voltage Vpv and input the actual voltage as the voltage at the negative output end of the second operational amplifier U2; the twentieth resistor R20, the twenty-first resistor R21, the twenty-second resistor R22, and the twenty-third resistor R23 constitute a threshold circuit for limiting the high value and low value of the hysteresis; the third capacitor C3 and the fourth capacitor C4 both serve as filter capacitors.

[0090] It should be noted that each photovoltaic input port of the inverter can be an energy storage port, which is respectively connected to the output ends of each photovoltaic module in the photovoltaic system; or, each photovoltaic input port of the inverter can be a communication port, which is respectively connected to the communication ends of each photovoltaic module; or, each photovoltaic input port of the inverter can also be other functional ports where coupled voltage may occur, which will not be listed one by one here. During the actual application process of the photovoltaic input port coupled voltage suppression circuit, the components in the circuit can be selected according to actual needs.

[0091] In summary, the photovoltaic input port coupled voltage suppression circuit provided by the embodiment of the present utility model can reliably identify and release the coupled voltage. When there is an input voltage at several photovoltaic input ports, it discharges the voltage coupled from the remaining photovoltaic input ports without input voltage, which can effectively eliminate the influence of the coupled voltage on the control process of the photovoltaic system, make the display of the port voltages on the upper computer and the APP more accurate, eliminate the user's electric shock risk, ensure the reliability and safety of the inverter, and further improve the reliability and safety of the photovoltaic system.

[0092] An embodiment of the present utility model also provides a photovoltaic system, which includes an inverter and the photovoltaic input port coupling voltage suppression circuit provided in any embodiment of the present utility model, and has corresponding beneficial effects. Exemplarily, the photovoltaic system may further include at least two photovoltaic modules. Each photovoltaic module is connected to the DC bus of the inverter through each photovoltaic input port of the inverter. Exemplarily, a controller may be included in the photovoltaic system for controlling the operating states of the components in the photovoltaic system, and the controller may be reused as the control module in the photovoltaic input port coupling voltage suppression circuit.

[0093] It should be understood that various forms of the processes shown above can be used, steps can be reordered, added or deleted. For example, the steps described in the present utility model can be executed in parallel, sequentially or in a different order, as long as the desired results of the technical solution of the present utility model can be achieved, and no limitation is imposed herein.

[0094] The above specific embodiments do not constitute a limitation to the protection scope of the present utility model. Those skilled in the art should understand that various modifications, combinations, sub - combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A photovoltaic input port coupling voltage suppression circuit, characterized in that Including: At least two coupling voltage release modules, which are respectively arranged corresponding to each photovoltaic input port in the inverter; One of the photovoltaic input ports includes a positive input terminal and a negative input terminal; The coupling voltage release module includes: A coupling voltage identification unit, which is connected between the positive input terminal and the negative input terminal of the photovoltaic input port corresponding to the coupling voltage release module where it is located; the coupling voltage identification unit is used to output a first identification signal when the voltage between the positive input terminal and the negative input terminal is lower than the coupling voltage threshold value, and output a second identification signal when the voltage between the positive input terminal and the negative input terminal is higher than the normal voltage threshold value; wherein, the normal voltage threshold value is greater than or equal to the coupling voltage threshold value; A discharge unit, which is connected between the positive input terminal and the negative input terminal of the photovoltaic input port corresponding to the coupling voltage release module where it is located; the discharge unit is used to conduct according to the first identification signal and turn off according to the second identification signal.

2. The photovoltaic input port coupling voltage suppression circuit according to claim 1, wherein In the coupling voltage release module, the output terminal of the coupling voltage identification unit is directly connected to the control terminal of the discharge unit; Or, The photovoltaic input port coupling voltage suppression circuit further includes: a control module, which includes at least two signal input terminals and at least two signal output terminals respectively corresponding to the at least two signal input terminals; each of the signal input terminals is respectively connected to the output terminal of each coupling voltage identification unit, and each of the signal output terminals is respectively connected to the control terminal of each discharge unit; wherein, a set of corresponding signal input terminal and signal output terminal are respectively connected to the coupling voltage identification unit and the discharge unit in the same coupling voltage release module; the control module is used to control the discharge unit receiving the first identification signal to conduct, and control the discharge unit receiving the second identification signal to turn off.

3. The photovoltaic input port coupling voltage suppression circuit according to claim 1 or 2, characterized in that The discharge unit includes: a first transistor and a first resistor; the first transistor and the first resistor are connected in series between the positive input terminal and the negative input terminal of the photovoltaic input port corresponding to the coupling voltage release module where it is located, and the control electrode of the first transistor is connected to the control terminal of the discharge unit.

4. The photovoltaic input port coupling voltage suppression circuit according to claim 1 or 2, characterized in that The normal voltage threshold value is equal to the coupling voltage threshold value; The coupling voltage identification unit includes: a first adjustable precision voltage regulator, a second resistor and a third resistor; The cathode of the first adjustable precision voltage regulator is respectively connected to the positive input terminal and the output terminal of the coupling voltage identification unit, the anode of the first adjustable precision voltage regulator is connected to the negative input terminal, the first end of the second resistor is connected to the positive input terminal, the second end of the second resistor is respectively connected to the first end of the third resistor and the reference electrode of the first adjustable precision voltage regulator, and the second end of the third resistor is connected to the negative input terminal; wherein, when the voltage at the second end of the second resistor is equal to the reference voltage of the first adjustable precision voltage regulator, the voltage between the positive input terminal and the negative input terminal is equal to the coupling voltage threshold value.

5. The photovoltaic input port coupling voltage suppression circuit according to claim 4, wherein, The coupling voltage identification unit further includes: A fourth resistor, which is connected between the positive input terminal and the cathode of the first adjustable precision voltage regulator; And / or, a first zener diode is connected between the reference electrode of the first controllable precision voltage stabilizer and the negative input terminal; And / or, a second zener diode is connected between the cathode of the first controllable precision voltage stabilizer and the negative input terminal.

6. The photovoltaic input port coupling voltage suppression circuit according to claim 1 or 2, wherein The coupling voltage identification unit includes: a first voltage stabilization sub-unit, a second voltage stabilization sub-unit, a self-locking sub-unit, and a discharge control sub-unit; A first end of the first voltage stabilization sub-unit is connected to the positive input terminal, and a second end of the first voltage stabilization sub-unit is connected to a first control end of the self-locking sub-unit; the first voltage stabilization sub-unit is configured to conduct when the voltage between the positive input terminal and the negative input terminal is greater than the normal voltage threshold value; A first end of the second voltage stabilization sub-unit is connected to the positive input terminal, and a second end of the second voltage stabilization sub-unit is connected to a second control end of the self-locking sub-unit; the second voltage stabilization sub-unit is configured to conduct when the voltage between the positive input terminal and the negative input terminal is greater than the coupling voltage threshold value; A first input end of the self-locking sub-unit is connected to the positive input terminal, a second input end of the self-locking sub-unit is connected to the negative input terminal, and an output end of the self-locking sub-unit is connected to a first end of the discharge control sub-unit; the self-locking sub-unit is configured to: control conduction between the second input end and the output end of the self-locking sub-unit when both the first voltage stabilization sub-unit and the second voltage stabilization sub-unit are conducting; enter a self-locking state when the first voltage stabilization sub-unit is turned off and the second voltage stabilization sub-unit is conducting; and release the self-locking state and control disconnection between the second input end and the output end of the self-locking sub-unit when the second voltage stabilization sub-unit is turned off; A second end of the discharge control sub-unit is connected to the positive input terminal, a third end of the discharge control sub-unit is connected to the negative input terminal, and a fourth end of the discharge control sub-unit is connected to the output end of the coupling voltage identification unit; the discharge control sub-unit is configured to: control connection between the first end and the fourth end of the discharge control sub-unit when conduction exists between the second input end and the output end of the self-locking sub-unit, so that the coupling voltage identification unit outputs the voltage received by the first end of the discharge control sub-unit; and control disconnection between the first end and the fourth end of the discharge control sub-unit when disconnection exists between the second input end and the output end of the self-locking sub-unit, so that the coupling voltage identification unit outputs the voltage received by the second end of the discharge control sub-unit.

7. The photovoltaic input port coupling voltage suppression circuit according to claim 6, wherein The first voltage stabilization sub-unit includes: a third zener diode and a first diode; an anode of the first diode is connected to the first end of the first voltage stabilization sub-unit, a cathode of the first diode is connected to a cathode of the third zener diode, and an anode of the third zener diode is connected to the second end of the first voltage stabilization sub-unit; The second voltage stabilizing sub-unit includes: a second controllable precision voltage stabilizer, a fifth resistor, and a sixth resistor; the cathode of the second controllable precision voltage stabilizer is respectively connected to the first end of the second voltage stabilizing sub-unit and the first end of the fifth resistor, the reference pole of the second controllable precision voltage stabilizer is respectively connected to the second end of the fifth resistor and the first end of the sixth resistor, and the anode of the second controllable precision voltage stabilizer is respectively connected to the second end of the second voltage stabilizing sub-unit and the second end of the sixth resistor; The self-locking sub-unit includes: a second transistor, a third transistor, a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor; the second transistor is connected between the first control end and the second control end of the self-locking sub-unit, the seventh resistor is connected between the first control end of the self-locking sub-unit and the second input end, the third transistor is connected between the second input end and the output end of the self-locking sub-unit, the eighth resistor is connected between the first input end and the output end of the self-locking sub-unit, the ninth resistor is connected between the control pole of the second transistor and the output end of the self-locking sub-unit, and the tenth resistor is connected between the control pole of the third transistor and the first control end of the self-locking sub-unit; The discharge control sub-unit includes: a second diode, a first capacitor, an eleventh resistor, a twelfth resistor, and a thirteenth resistor; the cathode of the second diode is connected to the first end of the discharge control sub-unit, the anode of the second diode is respectively connected to the first end of the first capacitor, the first end of the eleventh resistor, the first end of the twelfth resistor, and the first end of the thirteenth resistor, the second end of the eleventh resistor is connected to the second end of the discharge control sub-unit, the second ends of the first capacitor and the thirteenth resistor are both connected to the third end of the discharge control sub-unit, and the second end of the twelfth resistor is connected to the fourth end of the discharge control sub-unit.

8. The photovoltaic input port coupled voltage suppression circuit according to claim 1 or 2, characterized in that, The coupling voltage identification unit includes: A sampling sub-unit, the first input end of the sampling sub-unit is connected to the negative input end, and the second input end of the sampling sub-unit is connected to the positive input end; the sampling sub-unit is used to collect the voltage between the positive input end and the negative input end and convert it into a sampling voltage for output; A hysteresis comparison sub-unit, the input end of the hysteresis comparison sub-unit is connected to the output end of the sampling sub-unit, and the output end of the hysteresis comparison sub-unit is connected to the output end of the coupling voltage identification unit; the hysteresis comparison sub-unit is used to control the coupling voltage identification unit to output the first identification signal or the second identification signal according to the sampling voltage.

9. The photovoltaic input port coupling voltage suppression circuit according to claim 8, characterized in that, The sampling sub-unit includes: a first operational amplifier, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, and a second capacitor; the fifteenth resistor is connected between the first input end of the sampling sub-unit and the negative input end of the first operational amplifier, the sixteenth resistor is connected between the second input end of the sampling sub-unit and the positive input end of the first operational amplifier, the output end of the first operational amplifier is connected to the output end of the sampling sub-unit, the fourteenth resistor is connected between the negative input end and the output end of the first operational amplifier, and the second capacitor and the seventeenth resistor are connected in parallel between the positive input end of the first operational amplifier and the ground; The hysteresis comparator sub-unit includes: a second operational amplifier, a third capacitor, a fourth capacitor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a twenty-second resistor, and a twenty-third resistor; the eighteenth resistor is connected between the input end of the hysteresis comparator sub-unit and the negative input end of the second operational amplifier, the nineteenth resistor and the third capacitor are connected in parallel between the negative input end of the second operational amplifier and the ground, the first end of the twentieth resistor is connected to a first power supply signal, the second end of the twentieth resistor is connected to the positive input end of the second operational amplifier, the fourth capacitor and the twenty-first resistor are connected in parallel between the positive input end of the second operational amplifier and the ground, the output end of the second operational amplifier is connected to the output end of the hysteresis comparator sub-unit, the twenty-second resistor is connected between the positive input end and the output end of the second operational amplifier, the first end of the twenty-third resistor is connected to a second power supply signal, and the second end of the twenty-third resistor is connected to the output end of the second operational amplifier.

10. A photovoltaic system, characterized in that, Comprising: An inverter and a photovoltaic input port coupling voltage suppression circuit according to any one of claims 1-9.

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