Photovoltaic DC interface lightning stroke surge protection circuit and photovoltaic system

Abstract

The embodiment of the utility model discloses a photovoltaic DC interface lightning stroke surge protection circuit and a photovoltaic system. The photovoltaic direct current interface comprises a feed interface and a plurality of positive terminals; the photovoltaic direct current interface lightning stroke surge protection circuit comprises at least one first protection module, at least one second protection module and a third protection module. Each positive terminal is connected with one first protection module or one second protection module, each first protection module, each second protection module and the third protection module are connected to a common point, and the third protection module is connected with the feed interface; each of the first protection module and the second protection module comprises a first switch type device; each first switch type device is used for carrying out shunting protection on the third protection module; the first switch type device and the third protection module are further used for bearing the working voltage of the photovoltaic direct current interface and absorbing lightning stroke surge energy input through the photovoltaic direct current interface so as to reduce the lightning stroke surge voltage input to the photovoltaic direct current interface.

Description

Technical Field

[0001] The utility model embodiment relates to the technical field of photovoltaic interface lightning surge protection, and in particular to a photovoltaic direct current interface lightning surge protection circuit and a photovoltaic system. Background Art

[0002] In photovoltaic applications, varistors are generally used for lightning surge protection. However, under the action of DC voltage, the varistor will be polarized, which will cause the voltage in the two directions to be inconsistent. The voltage in the two directions will deviate, causing the varistor to be polarized. To delay this phenomenon, designers usually increase the DC breakdown voltage of the varistor, which will increase the residual voltage of the varistor, and thus make the varistor unable to provide good protection for the subsequent photovoltaic circuit. Utility Model Content

[0003] The embodiment of the utility model provides a photovoltaic DC interface lightning surge protection circuit and a photovoltaic system to improve the lightning surge protection of the photovoltaic DC interface.

[0004] In a first aspect, an embodiment of the utility model provides a photovoltaic DC interface lightning surge protection circuit, wherein the photovoltaic DC interface includes a feed interface and a plurality of positive terminals;

[0005] The photovoltaic DC interface lightning surge protection circuit includes at least one first protection module, at least one second protection module and a third protection module;

[0006] Each of the positive terminals is connected to a first protection module or a second protection module, each of the first protection modules, each of the second protection modules and the third protection module are connected to a common point, and the third protection module is connected to the feed interface;

[0007] The first protection module and the second protection module both include a first switch type device;

[0008] Each of the positive terminals forms a protection path with the feed interface through a first switch-type device and the third protection module, and each of the first switch-type devices is used to perform shunt protection on the third protection module; the first switch-type device and the third protection module are also used to withstand the working voltage of the photovoltaic DC interface and absorb lightning surge energy input through the photovoltaic DC interface to reduce the lightning surge voltage input to the photovoltaic DC interface.

[0009] Optionally, the first protection module and / or the second protection module further comprises at least one of a first patch device and a first clamp-type device;

[0010] The first switch-type device is connected in series with the first patch device and / or the first clamp-type device.

[0011] Optionally, the voltage borne by the first switch-type device is greater than or equal to 0.1 times the operating voltage.

[0012] Optionally, the clamping voltage of the third protection module is greater than the operating voltage between the positive terminal and the feeding interface.

[0013] Optionally, the third protection module includes at least one first lightning surge protection unit; the feed interface includes at least one feed terminal;

[0014] Each of the feed terminals is connected to one of the first lightning surge protection units, and each of the first lightning surge protection units is connected to the common point;

[0015] Each of the positive terminals forms a protection path with a feeding terminal through a first switch-type device and a first lightning surge protection unit.

[0016] Optionally, the third protection module further includes a second lightning surge protection unit;

[0017] The first end of the second lightning surge protection unit is connected to the common point, and the second end of the second lightning surge protection unit is connected to each of the first lightning surge protection units.

[0018] Optionally, the first lightning surge protection unit and / or the second lightning surge protection unit includes a second clamping device;

[0019] The first lightning surge protection unit and / or the second lightning surge protection unit further includes one or more of a second switch-type device, a second patch device and a first capacitor.

[0020] Optionally, the photovoltaic DC interface further includes a grounding terminal;

[0021] The photovoltaic DC interface lightning surge protection circuit also includes a fourth protection module;

[0022] The ground terminal is connected to the common point through the fourth protection module.

[0023] Optionally, the fourth protection module includes one or more of a third clamping device, a third switching device, a third patch device and a second capacitor.

[0024] In a second aspect, an embodiment of the utility model further provides a photovoltaic system, which includes the photovoltaic DC interface lightning surge protection circuit provided by any embodiment of the utility model.

[0025] The first switch-type device of the photovoltaic DC lightning surge protection circuit provided by the embodiment of the utility model can withstand most of the working voltage of the photovoltaic DC interface, and isolate the third protection module from most of the working voltage input by the positive terminal, reduce the influence of the third protection module on the working voltage of the positive terminal, solve the polarization problem of the existing lightning surge protection circuit caused by the action of DC voltage, thereby effectively avoiding the performance degradation of the third protection module due to the influence of the working voltage of the positive terminal, and thus improve the lightning surge protection of the photovoltaic DC interface. In addition, through the cooperation of the first switch-type device and the third protection module, the overvoltage input by the positive terminal can be clamped within the voltage range that the photovoltaic DC interface can withstand, thereby realizing the protection of the photovoltaic DC interface. In addition, the first switch-type device used in the photovoltaic DC lightning surge protection circuit has the characteristics of small size and low price, so it will reduce the volume of the photovoltaic DC lightning surge protection circuit and reduce the cost of the photovoltaic DC lightning surge protection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 A schematic diagram of a photovoltaic DC interface lightning surge protection circuit provided by the prior art;

[0028] Figure 2 A schematic diagram of a photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model;

[0029] Figure 3 A schematic diagram of the structure of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model;

[0030] Figure 4 A schematic diagram of the structure of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model;

[0031] Figure 5 A schematic diagram of the structure of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model;

[0032] Figure 6 A schematic diagram of the structure of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model;

[0033] Figure 7A schematic diagram of the structure of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model;

[0034] Figure 8 A schematic diagram of the structure of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model;

[0035] Fig. 9 A schematic diagram of the structure of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model;

[0036] Fig.10 A schematic diagram of the structure of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model;

[0037] Fig.11 A schematic structural diagram of another photovoltaic DC interface lightning surge protection circuit provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

[0039] It should be noted that the terms "first", "second", etc. in the specification and claims of the utility model and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the utility model described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0040] Figure 1 A schematic diagram of a photovoltaic DC interface lightning surge protection circuit provided by the prior art is shown in FIG. Figure 1 As shown, the photovoltaic DC interface lightning surge protection circuit includes multiple varistors R and multiple tripping mechanisms T. Each varistor R and a tripping mechanism T form a varistor with tripping;

[0041] Specifically, each photovoltaic DC interface includes a feed interface RTN, a ground terminal PE and at least one positive terminal PVN+ (N is a positive integer); each positive terminal PVN+ (N is a positive integer) is connected to the first end of a varistor with a trip, the feed interface RTN is connected to the first end of a varistor with a trip, and the ground terminal PE is connected to the first end of a varistor with a trip. The second end of each varistor with a trip connected to the feed interface RTN, the ground terminal PE and the positive terminal PVN+ (N is a positive integer) is connected.

[0042] Among them, the varistor R is mainly formed by sintering metal oxide grains, and a depletion layer will be formed between each grain of the varistor R. Under the action of the DC electric field, the varistor R will undergo polarization, that is, the impurity ions inside the grains will migrate to the depletion layer between the two grains, causing the leakage current of the varistor R to increase and the DC voltage of the varistor R to decrease. When the polarized DC voltage of the varistor R is reduced to below the operating voltage, the varistor R will continue to conduct, that is, the leakage current will increase, and the degradation will develop exponentially, and will eventually be burned due to excessive conduction current, and may even cause a fire.

[0043] The tripping mechanism T can timely cut off the photovoltaic DC interface lightning surge protection when the varistor R polarization fails, that is, when the leakage current is too large, thereby preventing the occurrence of fire and enhancing the safety of the photovoltaic DC interface lightning surge protection.

[0044] According to the above description, the varistor R will be polarized under the action of the DC electric field. The method of adding a tripping circuit cannot fundamentally solve the problem of polarization and high residual voltage of the varistor R, that is, it cannot provide good protection for the lightning surge of the photovoltaic DC interface. In this regard, the present application proposes a photovoltaic DC interface lightning surge protection circuit to improve the lightning surge protection of the photovoltaic DC interface.

[0045] Figure 2 A schematic diagram of a photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model is shown in FIG. Figure 1 As shown, the photovoltaic DC interface includes a feed interface RTN and a plurality of positive terminals PVN+ (N is a positive integer); the photovoltaic DC interface lightning surge protection circuit includes at least one first protection module 110, at least one second protection module 120 and a third protection module 130;

[0046] Each positive terminal PVN+ (N is a positive integer) is connected to a first protection module 110 or a second protection module 120, each first protection module 110, each second protection module 120 and the third protection module 130 are connected to a common point O, and the third protection module 130 is connected to the feeding interface RTN;

[0047] The first protection module 110 and the second protection module 120 both include a first switch type device 111;

[0048] Each positive terminal PVN+ (N is a positive integer) forms a protection path with the feeding interface RTN through a first switch type device 111 and a third protection module 130, and each first switch type device 111 is used to perform shunt protection on the third protection module 130; the first switch type device 111 and the third protection module 130 are also used to withstand the working voltage of the photovoltaic DC interface and absorb the lightning surge energy input through the photovoltaic DC interface to reduce the lightning surge voltage input to the photovoltaic DC interface.

[0049] Among them, the DC voltage of the photovoltaic DC interface borne by the first switch type device 111 is greater than the DC voltage of the photovoltaic DC interface borne by the third protection module 130, and the lightning surge energy absorbed by the first switch type device 111 is greater than the lightning surge energy absorbed by the third protection module 130. In addition, the first switch type device 111 has a certain continuous current interruption capability (for example: >5A10ms or more), and can be automatically shut down after being turned on to avoid damage due to long-term continuous current. The first switch type device 111 includes any one of a gas discharge tube, a graphite gap, a ram horn gap, and a surge suppression thyristor, which is not specifically limited in this solution.

[0050] It should be noted that the number of positive terminals PVN+ (N is a positive integer) needs to be set according to actual needs, and this solution does not make specific restrictions on this.

[0051] According to the above connection relationship, the working principle of the photovoltaic DC interface lightning surge protection circuit is explained in the same way:

[0052] The operating voltage of the positive terminal PVN+ (N is a positive integer) should be less than the breakdown voltage of the first switch-type device 111, and the breakdown voltage is a voltage that can turn on the first protection module 110 or the second protection module 120. Therefore, when the first switch-type device 111 is subjected to the operating voltage of the photovoltaic interface, the third protection module 130 can be isolated from the operating voltage input by the positive terminal PVN+ (N is a positive integer).

[0053] Based on the connection of the photovoltaic DC interface lightning surge protection circuit, the process of photovoltaic DC interface lightning surge protection is described:

[0054] During the period when the working voltage is output at the positive terminal PVN+ (N is a positive integer), the first switch-type device 111 can withstand most of the working voltage of the photovoltaic DC interface and isolate the third protection module 130 from most of the working voltage input at the positive terminal PVN+ (N is a positive integer), thereby reducing the influence of the working voltage of the positive terminal PVN+ (N is a positive integer) on the third protection module 130, thereby avoiding the performance degradation caused by the working voltage of the positive terminal PVN+ (N is a positive integer) on the second protection module 120.

[0055] When an overvoltage is input to the positive terminal PVN+ (N is a positive integer), if the input overvoltage is less than the breakdown voltage of the first switch type device 111, the first switch type device 111 will not be turned on, and the first switch type device 111 can protect the photovoltaic DC interface.

[0056] If the input overvoltage is greater than or equal to the breakdown voltage of the first switch-type device 111, the first switch-type device 111 is turned on, and the third protection module 130 clamps the instantaneous overvoltage within the voltage range that the photovoltaic DC interface can withstand, thereby protecting the photovoltaic DC interface.

[0057] In addition, a plurality of positive terminals PVN+ (N is a positive integer) are provided, and each positive terminal PVN+ (N is a positive integer) forms a protection path with the feeding interface RTN through a first switch type device 111 and a third protection module 130. Each first switch type device 111 can perform shunt protection on the third protection module 130 to prevent the third protection module 130 from being burned due to excessive input current.

[0058] The first switch type device 111 of the photovoltaic DC lightning surge protection circuit provided by the embodiment of the utility model can withstand most of the working voltage of the photovoltaic DC interface, and isolate the third protection module 130 from most of the working voltage input by the positive terminal PVN+ (N is a positive integer), reduce the influence of the working voltage of the positive terminal PVN+ (N is a positive integer) on the third protection module 130, solve the polarization problem caused by the DC voltage of the existing lightning surge protection circuit, thereby effectively avoiding the influence of the working voltage of the positive terminal PVN+ (N is a positive integer) on the third protection module 130, and thus improve the lightning surge protection of the photovoltaic DC interface. Through the cooperation of the first switch type device 111 and the third protection module 130, the overvoltage input by the positive terminal PVN+ (N is a positive integer) can be clamped within the voltage range that the photovoltaic DC interface can withstand, thereby realizing the protection of the photovoltaic DC interface. In addition, the first switch type device 111 used in the photovoltaic DC lightning surge protection circuit has the characteristics of small size and low price, so it will reduce the volume of the photovoltaic DC lightning surge protection circuit and reduce the cost of the photovoltaic DC lightning surge protection circuit.

[0059] Based on the above embodiment, optionally, Figure 3 A schematic diagram of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model. Figure 3 As shown, the first protection module 110 and / or the second protection module 120 also includes at least one of a first patch device 112 and a first clamping device 113 ; the first switch device 111 is connected in series with the first patch device 112 and / or the first clamping device 113 .

[0060] The components included in the first protection module 110 and the second protection module 120 may be the same or different. Figure 3 In the embodiment, the first protection module 110 includes a first switch-type device 111 and a first patch device 112, which are connected in series between the positive terminal PVN+ (N is a positive integer) and the common point O; the first patch device 112 can limit the current flowing into the third protection module 130 through the first switch-type device 111 to prevent the third protection module 130 from being burned due to excessive current flowing therethrough. The second protection module 120 includes a first switch-type device 111 and a first clamp-type device 113, which are connected in series between the positive terminal PVN+ (N is a positive integer) and the common point O; the first clamp-type device 113 can absorb the lightning surge energy input through the photovoltaic DC interface to reduce the lightning surge voltage input to the photovoltaic DC interface.

[0061] In addition, the first patch device 112 includes a device such as a fuse, a trip device or a current limiting device, which can prevent the third protection module 130 from being burned due to excessive current by limiting the current flowing into the third protection module 130 through the first switch type device 111.

[0062] Based on the above embodiment, optionally, the voltage borne by the first switch-type device 111 is greater than or equal to 0.1 times the operating voltage.

[0063] Among them, the DC voltage of the photovoltaic DC interface borne by the first switch type device 111 is greater than or equal to 0.1 of the working voltage, so that the first switch type device 111 can withstand most of the working voltage of the photovoltaic DC interface, so as to isolate the third protection module 130 from most of the working voltage input from the positive terminal PVN+ (N is a positive integer), reduce the influence of the working voltage of the positive terminal PVN+ (N is a positive integer) on the third protection module 130, and thus avoid the third protection module 130 being affected by the working voltage of the positive terminal PVN+ (N is a positive integer) and causing performance degradation.

[0064] It should be noted that the switch-type devices used in this scheme include any one of a gas discharge tube, a graphite gap, a horn gap and a surge suppression thyristor. In order to facilitate the description of the photovoltaic DC interface lightning surge protection circuit structure provided in different embodiments of this scheme, the following is an example in which the switch-type device uses a gas discharge tube and the patch device uses a thermal release.

[0065] For example, Figure 4 A schematic diagram of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model is shown in FIG. Figure 4 As shown, the first protection module 110 and the second protection module 120 both include a first switch type device 111; each positive terminal PVN+ (N is a positive integer) is connected to one end of a first switch type device 111, and the other end of each first switch type device 111 is connected to the third protection module 130.

[0066] The first switch type device 111 adopts the first gas discharge tube P1, which is a gap type lightning surge protection element. The gas discharge tube adopts a ceramic sealed package, and the interior is composed of two or more metal electrodes with gaps, which are filled with inert gas (such as argon or neon). The gas discharge tube has a strong lightning surge absorption capacity, that is, a strong discharge capacity, a large flow rate, a high insulation resistance, a small parasitic capacitance, no leakage current, and a small size.

[0067] The first switch type device 111 adopts the first gas discharge tube P1. Compared with the prior art, each positive terminal PVN+ (N is a positive integer) is connected to a varistor that only has the function of absorbing lightning surge energy. There is no need to design a circuit to reduce the polarization of the varistor. Therefore, the first switch type device 111 is used to connect each positive terminal PVN+ (N is a positive integer), which simplifies the design of the photovoltaic DC interface lightning surge protection circuit and reduces the design cost and volume of the photovoltaic DC interface lightning surge protection circuit.

[0068] During the period when the working voltage is output at the positive terminal PVN+ (N is a positive integer), the first gas discharge tube P1 can withstand most of the working voltage of the photovoltaic DC interface, and isolate the third protection module 130 from most of the working voltage input by the positive terminal PVN+ (N is a positive integer), thereby reducing the third protection module 130 from being polarized by the working voltage of the positive terminal PVN+ (N is a positive integer), thereby avoiding the third protection module 130 from being affected by the working voltage of the positive terminal PVN+ (N is a positive integer) and causing performance degradation, thereby reducing the residual voltage of the lightning surge protection and improving the reliability of the photovoltaic DC interface lightning surge protection circuit.

[0069] When the voltage input to both ends of the first gas discharge tube P1 through the positive terminal PVN+ (N is a positive integer) reaches the point where the gas in the first gas discharge tube P1 breaks down, the first gas discharge tube P1 starts to conduct and discharge, and changes from high impedance to low impedance, so that the first gas discharge tube P1 enters an arc discharge state, at which time the voltage across both ends of the first gas discharge tube P1 is the arc voltage of the first gas discharge tube P1. The third protection module 130 is connected to the connection points of all first gas discharge tubes P1, and the third protection module 130 can absorb the remaining lightning surge energy after each first gas discharge tube P1 breaks down, that is, the third protection module 130 clamps the overvoltage input through each first gas discharge tube P1 within the voltage range that the photovoltaic DC interface can withstand, so as to protect the photovoltaic DC interface.

[0070] On the basis of the above embodiment, optionally, the clamping voltage of the third protection module 130 is greater than the operating voltage between the positive terminal PVN+ (N is a positive integer) and the feeding interface RTN.

[0071] The third protection module 130 can clamp the voltage input from each positive terminal PVN+ (N is a positive integer) to the feeding interface RTN. Therefore, the clamping voltage of the third protection module 130 needs to be greater than the operating voltage between the positive terminal PVN+ (N is a positive integer) and the feeding interface RTN, thereby preventing the positive terminal PVN+ (N is a positive integer) of each protection path from forming a continuous current with the feeding interface RTN.

[0072] Based on the above embodiment, optionally, Figure 5 A schematic diagram of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model. Figure 5 As shown, the third protection module 130 includes at least one first lightning surge protection unit 131; the feeding interface RTN includes at least one feeding terminal RTNM (M is a positive integer);

[0073] Each feeding terminal RTNM (M is a positive integer) is connected to a first lightning protection surge unit 131, and each first lightning protection surge unit 131 is connected to a common point O; each positive terminal PVN+ (N is a positive integer) forms a protection path with a feeding terminal RTNM (M is a positive integer) through a first switching device 111 and a first lightning protection surge unit 131.

[0074] Specifically, the first lightning surge protection unit 131 in each protection path can clamp the voltage input from the positive terminal PVN+ (N is a positive integer) to the feeding terminal RTNM (M is a positive integer) to prevent the voltage input from the positive terminal PVN+ (N is a positive integer) to the feeding terminal RTNM (M is a positive integer) from being too large and burning the photovoltaic DC interface.

[0075] In addition, each positive terminal PVN+ (N is a positive integer) forms a protection path with a feeding terminal RTNM (M is a positive integer) through a first switching device 111 and a first lightning surge protection unit 131, thereby dispersing the lightning surge energy input through the photovoltaic DC interface, that is, reducing the lightning surge energy entering each protection path, and then reducing the lightning surge current input into each protection path, so as to prevent the lightning surge current from being too large and damaging the lightning surge protection circuit.

[0076] Based on the above embodiment, optionally, Figure 6 A schematic diagram of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model. Figure 6 As shown, the third protection module 130 further includes a second lightning surge protection unit 132 ; a first end of the second lightning surge protection unit 132 is connected to the common point O, and a second end of the second lightning surge protection unit 131 is connected to each first lightning surge protection unit 131 .

[0077] Specifically, the second lightning surge protection unit 132 can clamp each voltage input from the positive terminal PVN+ (N is a positive integer) to the feeding terminal RTNM (M is a positive integer) to prevent the voltage input from the positive terminal PVN+ (N is a positive integer) to the feeding terminal RTNM (M is a positive integer) from being too large and burning the photovoltaic DC interface.

[0078] Based on the above embodiments, optionally, the first lightning protection surge unit and / or the second lightning protection surge unit includes a second embedded device; the first lightning protection surge unit and / or the second lightning protection surge unit also includes one or more of a second switch type device, a second patch device and a first capacitor.

[0079] Among them, the second clamping device on each protection path can clamp the voltage input from the positive terminal to the feed terminal). The second patch device can be set to cut off the photovoltaic DC interface lightning surge protection in time when the temperature of the second clamping device is abnormal, thereby preventing the occurrence of fire and enhancing the safety of the photovoltaic DC interface lightning surge protection. The second switch type device is set to enable the first switch type device and the second switch type device to jointly bear the working voltage of the positive terminal. The first capacitor is connected in parallel to the two ends of the second switch type device. Since the first capacitor is a high impedance device under DC, the first switch type device and the second switch type device will jointly bear the DC voltage. In the case of lightning surge, the first capacitor C1 is low impedance at the high frequency of lightning, so the impedance of the first switch type device will be much greater than the first capacitor C1, so the two ends of the first switch type device will give priority to the second switch device under the lightning surge, thereby realizing the staggered action of the first switch type device and the second switch type device, thereby reducing the peak voltage.

[0080] Among them, the first lightning protection surge unit 131 includes a second clamping type device connected in series with a second switch type device and / or a second patch device, and the first capacitor is connected in parallel with the second switch type device; the second lightning protection surge unit 132 includes a second clamping type device connected in series with a second switch type device and / or a second patch device, and the first capacitor is connected in parallel with the second switch type device.

[0081] It should be noted that: the number of the second clamping device, the second switch device, the second patch device and the first capacitor included in the first lightning protection surge unit 131 or the second lightning protection surge unit 132 is not limited. In addition, the above description is only an exemplary example of the connection relationship between the various devices in the first lightning protection surge unit 131 and the second lightning protection surge unit 132. This case does not limit this, and the designer can set it specifically according to actual needs.

[0082] In order to facilitate the description of the photovoltaic DC interface lightning surge protection circuit structure provided by different embodiments of the present scheme, the following description is given by taking the switch type device using a gas discharge tube, the clamp type device using a varistor, and the patch device using a thermal release as an example.

[0083] Based on the above embodiment, optionally, Figure 7 A schematic diagram of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model. Figure 7 As shown, the first lightning surge protection unit 131 includes a second clamping device and a second patch device, the second patch device includes a first thermal release T1, and the second clamping device includes a first varistor R1.

[0084] When the voltage value borne by the varistor exceeds the steady-state voltage of its rated operating voltage, it will cause thermal breakdown damage. At this time, the leakage current of the varistor is too large, which will generate a lot of heat energy and eventually cause the varistor to explode. In this regard, a thermal release is connected in series with the varistor to cut off the photovoltaic DC interface lightning surge protection in time when the leakage current of the varistor is too large, thereby preventing the occurrence of fire and enhancing the safety of the photovoltaic DC interface lightning surge protection.

[0085] Specifically, the first thermal release T1 can protect the first varistor R1, and the first varistor R1 can clamp the voltage input from the positive terminal PVN+ (N is a positive integer) to the feeding terminal RTNM (M is a positive integer) to prevent the voltage input from the positive terminal PVN+ (N is a positive integer) to the ground terminal PE or the feeding terminal RTNM (M is a positive integer) from being too large and burning the photovoltaic DC interface.

[0086] Based on the above embodiment, optionally, Figure 8A schematic diagram of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model. Figure 8 As shown, the first lightning surge protection unit 131 and the second lightning surge protection unit 132 both include a second clamping device and a second patch device, the second patch device includes a first thermal release T1, and the second clamping device includes a first varistor R1.

[0087] Among them, the first thermal release T1 in the first lightning protection surge unit 131 can protect the first varistor R1, and the first thermal release T1 in the second lightning protection surge unit 132 can protect the first varistor R1. The first varistor R1 in the first lightning protection surge unit 131 can clamp a voltage input from the positive terminal PVN+ (N is a positive integer) to the ground terminal PE or the feeding terminal RTNM (M is a positive integer), and the first varistor R1 in the second lightning protection surge unit 132 can clamp each voltage input from the positive terminal PVN+ (N is a positive integer) to the ground terminal PE or the feeding terminal RTNM (M is a positive integer).

[0088] Based on the above embodiment, optionally, Fig. 9 A schematic diagram of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model. Fig. 9 As shown, the first lightning surge protection unit 131 includes a second clamping device, a second patch device, a second switching device and a first capacitor C1, and the second lightning surge protection unit 132 includes a second clamping device and a second patch device. The second patch device includes a first thermal release T1, the second clamping device includes a first varistor R1, and the second switching device includes a second gas discharge tube P2.

[0089] Specifically, under normal wiring, that is, when the positive terminal PVN+ (N is a positive integer) is connected to the positive output terminal of the photovoltaic panel and the feed terminal RTNM (M is a positive integer) is connected to the negative output terminal of the photovoltaic panel, since the first capacitor C1 is a high impedance device under DC, the first gas discharge tube P1 and the second gas discharge tube P2 jointly bear the DC voltage. In the case of a lightning surge, the first capacitor C1 is a low impedance under the high frequency of lightning, so the impedance of the first gas discharge tube P1 is much greater than that of the first capacitor C1, so P1 will act first at both ends of P1 under a lightning surge, and the second gas discharge tube P2 will act after the first gas discharge tube P1 acts, so the first capacitor C1 and the second gas discharge tube P2 are connected in parallel, so that the first gas discharge tube P1 and the second gas discharge tube P2 can act at different peaks, thereby reducing the peak voltage.

[0090] It should be noted that: the first varistor R1 needs to select a clamping voltage greater than the working voltage input to the positive terminal PVN+ (N is a positive integer). As a result, the overall platform residual voltage of the photovoltaic DC interface will be lower than the residual voltage generated when the positive terminal PVN+ (N is a positive integer) of the prior art is directly connected to the varistor for lightning surge protection.

[0091] Based on the above embodiment, optionally, Fig.10 A schematic diagram of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model. Fig.10 As shown, the photovoltaic DC interface further includes a grounding terminal PE; the photovoltaic DC interface lightning surge protection circuit further includes a fourth protection module 140; and the grounding terminal PE is connected to the common point O through the fourth protection module 140.

[0092] Among them, the third protection module 130 can clamp the voltage input from the positive terminal PVN+ (N is a positive integer) to the feeding terminal RTNM (M is a positive integer) to prevent the voltage input from the positive terminal PVN+ (N is a positive integer) to the feeding terminal RTNM (M is a positive integer) from being too large to burn the photovoltaic DC interface; the fourth protection module 140 can clamp the voltage input from the positive terminal PVN+ (N is a positive integer) to the ground terminal PE to prevent the voltage input from the positive terminal PVN+ (N is a positive integer) to the ground terminal PE from being too large to burn the photovoltaic DC interface; the third The protection module 130 and the fourth protection module 140 can clamp the voltage input from the feeding terminal RTNM (M is a positive integer) to the grounding terminal PE to prevent the voltage input from the feeding terminal RTNM (M is a positive integer) to the grounding terminal PE from being too large and burning the photovoltaic DC interface; the third protection module 130 and the fourth protection module 140 can also clamp the voltage input from the grounding terminal PE to the feeding terminal RTNM (M is a positive integer) to prevent the voltage input from the grounding terminal PE to the feeding terminal RTNM (M is a positive integer) from being too large and burning the photovoltaic DC interface.

[0093] Based on the above embodiment, optionally, the fourth protection module 140 includes one or more of a third clamping device, a third switch device, a third patch device and a second capacitor.

[0094] It should be noted that the number of the third clamping device, the third switch device, the third patch device and the second capacitor included in the fourth protection module 140 is not limited, and the connection relationship between the devices is not limited in this case, and designers can make specific settings according to actual needs.

[0095] Based on the above embodiment, optionally, Fig.11 A schematic diagram of another photovoltaic DC interface lightning surge protection circuit provided by an embodiment of the utility model. Fig.11As shown, the third protection module 130 includes a first lightning surge protection unit 131, the first lightning surge protection unit 131 includes a second clamping device, a second patch device and a second switching device, the second patch device includes a first thermal release T1, the second clamping device includes a first varistor R1, and the second switching device includes a second gas discharge tube P2. The fourth protection module 140 includes a third clamping device, a third patch device and a third switching device, the third patch device includes a second thermal release T2, the third clamping device includes a second varistor R2, and the third switching device includes a third gas discharge tube P3.

[0096] Specifically, the second thermal trip T2 can protect the first varistor R1, and the second thermal trip T2 can protect the second varistor R2. The first varistor R1 can clamp the voltage input from the positive terminal PVN+ (N is a positive integer) to the feeding terminal RTNM (M is a positive integer); the second varistor R2 can clamp the voltage input from the positive terminal PVN+ (N is a positive integer) to the ground terminal PE; the first varistor R1 and the second varistor R2 can clamp the voltage input from the feeding terminal RTNM (M is a positive integer) to the ground terminal PE, and can also clamp the voltage input from the ground terminal PE to the feeding terminal RTNM (M is a positive integer).

[0097] When the positive terminal PVN+ (N is a positive integer) is connected to the positive output terminal of the photovoltaic panel and the feed terminal RTNM (M is a positive integer) is connected to the negative output terminal of the photovoltaic panel, the first gas discharge tube P1 and the second gas discharge tube P2 jointly bear the working voltage of the positive terminal PVN+ (N is a positive integer). When the positive terminal PVN+ (N is a positive integer) is connected to the positive output terminal of the photovoltaic panel and the ground terminal PE is connected to the negative output terminal of the photovoltaic panel, the first gas discharge tube P1 and the third gas discharge tube P3 jointly bear the working voltage of the positive terminal PVN+ (N is a positive integer). When the feed terminal RTNM (M is a positive integer) is connected to the positive output terminal of the photovoltaic panel and the ground terminal PE is connected to the negative output terminal of the photovoltaic panel, the second gas discharge tube P2 and the third gas discharge tube P3 jointly bear the working voltage of the positive terminal PVN+ (N is a positive integer). Therefore, the first varistor R1 and / or the second varistor R2 arranged in any two devices of the first gas discharge tube P1, the second gas discharge tube P2 and the third gas discharge tube P3 can avoid being subjected to most of the DC voltage, thereby solving the polarization problem of the existing lightning surge protection circuit caused by the action of the DC voltage, thereby effectively avoiding the performance degradation of the first varistor R1 or the second varistor R2 due to the working voltage or DC voltage of the positive terminal PVN+ (N is a positive integer), thereby reducing the residual voltage of the lightning surge protection.

[0098] An embodiment of the utility model further provides a photovoltaic system, which includes the photovoltaic DC interface lightning surge protection circuit provided by any embodiment of the utility model. Therefore, the photovoltaic system has the beneficial effects of the photovoltaic DC interface lightning surge protection circuit provided by any embodiment of the utility model, which will not be elaborated in this case.

[0099] In addition, the manufacturing process of the photovoltaic DC interface lightning surge protection circuit provided by this solution has significantly reduced costs, processes, materials, and sizes compared to conventional modules.

[0100] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0101] The above specific implementations do not constitute a limitation on the protection scope of the present utility model. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. A photovoltaic DC interface lightning surge protection circuit, characterized in that: The photovoltaic DC interface includes a feed interface and a plurality of positive terminals; The photovoltaic DC interface lightning surge protection circuit includes at least one first protection module, at least one second protection module and a third protection module; Each of the positive terminals is connected to a first protection module or a second protection module, each of the first protection modules, each of the second protection modules and the third protection module are connected to a common point, and the third protection module is connected to the feed interface; The first protection module and the second protection module both include a first switch type device; Each of the positive terminals forms a protection path with the feed interface through a first switch-type device and the third protection module, and each of the first switch-type devices is used to perform shunt protection on the third protection module; the first switch-type device and the third protection module are also used to withstand the working voltage of the photovoltaic DC interface and absorb lightning surge energy input through the photovoltaic DC interface to reduce the lightning surge voltage input to the photovoltaic DC interface.

2. The photovoltaic DC interface lightning surge protection circuit according to claim 1, characterized in that: The first protection module and / or the second protection module further comprises at least one of a first patch device and a first clamp-type device; The first switch-type device is connected in series with the first patch device and / or the first clamp-type device.

3. The photovoltaic DC interface lightning surge protection circuit according to claim 1, characterized in that: The voltage borne by the first switch type device is greater than or equal to 0.1 times the operating voltage.

4. The photovoltaic DC interface lightning surge protection circuit according to claim 1, characterized in that: The clamping voltage of the third protection module is greater than the operating voltage between the positive terminal and the feeding interface.

5. The photovoltaic DC interface lightning surge protection circuit according to claim 1, characterized in that: The third protection module includes at least one first lightning surge protection unit; the feed interface includes at least one feed terminal; Each of the feed terminals is connected to one of the first lightning surge protection units, and each of the first lightning surge protection units is connected to the common point; Each of the positive terminals forms a protection path with a feeding terminal through a first switch-type device and a first lightning surge protection unit.

6. The photovoltaic DC interface lightning surge protection circuit according to claim 5, characterized in that: The third protection module also includes a second lightning surge protection unit; A first end of the second lightning surge protection unit is connected to the common point, and a second end of the second lightning surge protection unit is connected to each of the first lightning surge protection units.

7. The photovoltaic DC interface lightning surge protection circuit according to claim 6, characterized in that: The first lightning surge protection unit and / or the second lightning surge protection unit comprises a second clamping device; The first lightning surge protection unit and / or the second lightning surge protection unit further includes one or more of a second switch-type device, a second patch device and a first capacitor.

8. The photovoltaic DC interface lightning surge protection circuit according to claim 1, characterized in that: The photovoltaic DC interface also includes a grounding terminal; The photovoltaic DC interface lightning surge protection circuit also includes a fourth protection module; The ground terminal is connected to the common point through the fourth protection module.

9. The photovoltaic DC interface lightning surge protection circuit according to claim 8, characterized in that: The fourth protection module includes one or more of a third clamping device, a third switching device, a third patch device and a second capacitor.

10. A photovoltaic system, characterized in that: The invention comprises the photovoltaic DC interface lightning surge protection circuit as described in any one of claims 1 to 9.

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