Photovoltaic inverter overvoltage protection circuit and photovoltaic system

Abstract

The utility model provides a photovoltaic inverter overvoltage protection circuit and a photovoltaic system, and relates to the technical field of photovoltaic inverters. The circuit comprises a sampling module, a comparison module, a voltage overturning module and a switch module, the input end of the switch module and the input end of the sampling module are both used for receiving the input voltage of a photovoltaic panel, and the output end of the switch module is connected with a boosting module. The output end of the sampling module is sequentially connected with the comparison module and the voltage overturning module, and the output end of the voltage overturning module is connected with the control end of the switch module. The sampling module is used for outputting a sampling voltage according to the received input voltage of the photovoltaic panel. The comparison module is used for comparing the sampling voltage with a reference voltage and outputting a comparison voltage. The voltage flipping module is used for flipping the comparison voltage. And when the sampling voltage is detected to be greater than the reference voltage, the voltage overturning module outputs a low level to quickly control the switch module to be switched off, and power supply to a subsequent load is stopped, so that key devices in the photovoltaic inverter are protected.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic inverters, and in particular to a photovoltaic inverter overvoltage protection circuit and a photovoltaic system. Background Art

[0002] Photovoltaic system is a new type of power generation system that uses the photovoltaic effect of photovoltaic solar panels to convert solar radiation energy into electrical energy for use in the mains grid. In a photovoltaic system, the photovoltaic inverter (PV inverter) can convert the variable DC voltage generated by photovoltaic solar panels into AC power of mains frequency and output it to the mains grid.

[0003] However, in actual use, factors such as weather and light intensity may cause overvoltage in the input of the photovoltaic inverter, thereby damaging the key components of the photovoltaic inverter, and in severe cases even causing accidents such as fire.

[0004] Therefore, how to quickly and easily protect key components in a photovoltaic inverter when input overvoltage occurs is a technical problem that needs to be solved urgently by those skilled in the art. Utility Model Content

[0005] The purpose of the present application is to provide a photovoltaic inverter overvoltage protection circuit and system to ensure that key components in the photovoltaic inverter can be quickly and easily protected when the input is overvoltage.

[0006] In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0007] On the one hand, an embodiment of the present application provides a photovoltaic inverter overvoltage protection circuit, which includes a sampling module, a comparison module, a voltage flip module and a switch module. The input end of the switch module and the input end of the sampling module are both used to receive the photovoltaic panel input voltage, and the output end of the switch module is connected to the input end of the boost module. The output end of the sampling module is connected to the comparison module and the voltage flip module in turn, and the output end of the voltage flip module is connected to the control end of the switch module.

[0008] The sampling module is used to output a sampling voltage to the comparison module according to the received photovoltaic panel input voltage. The comparison module is used to compare the sampling voltage with a reference voltage and output the comparison voltage to the voltage flip module.

[0009] The voltage flip module is used to flip the comparison voltage. When the sampling voltage is greater than the reference voltage, the voltage flip module outputs a low level to control the switch module to turn off.

[0010] Furthermore, the circuit also includes an input module, the input end of the input module is connected to the photovoltaic panel, the first output end of the input module is respectively connected to the input end of the switch module and the second input end of the sampling module, and the second output end of the input module is respectively connected to the input end of the boost module and the first input end of the sampling module.

[0011] The first output terminal of the input module is used to output a positive photovoltaic panel input voltage, and the second output terminal of the input module is used to output a negative photovoltaic panel input voltage.

[0012] Furthermore, the switch module includes a first N-type switch tube, a first resistor, a second resistor, a third resistor and a relay; one end of the first resistor is connected to the first output end of the input module, and the other end of the first resistor is connected to the input end of the boost module.

[0013] The relay includes a contact switch and a relay coil, the contact switch is connected in parallel with the first resistor, one end of the relay coil is connected to the power supply, the other end of the relay coil is connected to the first port of the first N-type switch tube, the control end of the first N-type switch tube is respectively connected to one end of the second resistor and the third resistor, the other end of the second resistor is connected to the output end of the voltage flip module, and the other end of the third resistor and the second port of the first N-type switch tube are both grounded.

[0014] Furthermore, the sampling module includes an adjustment unit and an amplification unit, the first input end and the second input end of the adjustment unit are respectively connected to the second output end and the first output end of the input module, the first output end and the second output end of the adjustment unit are respectively connected to the first input end and the second input end of the amplification unit, and the output end of the amplification unit is connected to the input end of the comparison module.

[0015] Furthermore, the adjustment unit includes multiple first adjustment resistors and multiple second adjustment resistors, and the multiple first adjustment resistors are connected in series in sequence between the second output end of the input module and the first input end of the amplification unit; the multiple second adjustment resistors are connected in series in sequence between the first output end of the input module and the second input end of the amplification unit.

[0016] The amplification unit includes an amplifier, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and a first capacitor; the inverting input terminal of the amplifier is respectively connected to one end of the fourth resistor, the fifth resistor and the first capacitor, the other end of the fourth resistor is connected to the first output terminal of the adjustment unit, and the output terminal of the amplifier is respectively connected to the other end of the fifth resistor, the other end of the first capacitor and the input terminal of the comparison module.

[0017] The in-phase input terminal of the amplifier is connected to one end of the sixth resistor and the seventh resistor respectively, the other end of the sixth resistor is connected to the second output terminal of the adjustment unit, and the other end of the seventh resistor is grounded.

[0018] Furthermore, the comparison module includes a comparator, a reference voltage adjustment unit, an eighth resistor, a ninth resistor, a tenth resistor and a second capacitor; the non-inverting input terminal of the comparator is respectively connected to one end of the eighth resistor and the ninth resistor, the other end of the eighth resistor is connected to the output end of the sampling module, and the other end of the ninth resistor is grounded.

[0019] The inverting input end of the comparator is connected to the reference voltage adjustment unit, the output end of the comparator is respectively connected to one end of the tenth resistor, one end of the second capacitor and the input end of the voltage flip module, the other end of the tenth resistor is connected to the reference power supply, and the other end of the second capacitor is grounded.

[0020] Furthermore, the reference voltage adjustment unit includes an eleventh resistor and a twelfth resistor, the inverting input terminal of the comparator is connected to one end of the eleventh resistor and the twelfth resistor respectively, the other end of the eleventh resistor is connected to the reference power supply, and the other end of the twelfth resistor is grounded.

[0021] Further, the voltage flip module includes a second N-type switch tube, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor and a sixteenth resistor. The control end of the second N-type switch tube is connected to one end of the thirteenth resistor and the fourteenth resistor respectively, the other end of the thirteenth resistor is connected to the output end of the comparison module, and the other end of the fourteenth resistor and the second port of the second N-type switch tube are both grounded.

[0022] The first port of the second N-type switch tube is connected to one end of the fifteenth resistor and the sixteenth resistor respectively, the other end of the fifteenth resistor is connected to the reference power supply, and the other end of the sixteenth resistor is connected to the control end of the switch module.

[0023] Furthermore, the circuit also includes a processor, a first port and a second port of the processor are respectively connected to the output end of the sampling module and the input end of the boost module, and the processor is used to adjust the boost value of the boost module according to the size of the sampling voltage.

[0024] The third port and the fourth port of the processor are connected to the output end of the comparison module and the control end of the switch module respectively. The processor is also used to control the on and off of the switch module according to the comparison voltage.

[0025] On the other hand, an embodiment of the present application further provides a photovoltaic system, which includes the photovoltaic inverter overvoltage protection circuit as described in any of the aforementioned implementations.

[0026] Compared with the prior art, this application has the following beneficial effects:

[0027] The present application provides a photovoltaic inverter overvoltage protection circuit and a photovoltaic system. The photovoltaic panel input voltage is received by a sampling module, and the sampled voltage is output to a comparison module. The sampling voltage is compared with a preset reference voltage by the comparison module to detect whether the photovoltaic panel input voltage is overvoltage. The voltage output by the comparison module is flipped by a voltage flip module, and the on and off of the switch module is controlled by positive logic to ensure that when the photovoltaic panel input voltage is overvoltage, the voltage flip module outputs a low level to quickly control the switch module to turn off, stop the power supply to the subsequent load, and thus protect the key components in the photovoltaic inverter.

[0028] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians of the art without making creative work are within the scope of protection of the present application.

[0030] Figure 1 One of the structural schematic diagrams of a photovoltaic inverter overvoltage protection circuit provided in an embodiment of the present application;

[0031] Figure 2 A second structural schematic diagram of a photovoltaic inverter overvoltage protection circuit provided in an embodiment of the present application;

[0032] Figure 3 A circuit diagram of an input module provided in an embodiment of the present application;

[0033] Figure 4 A circuit diagram of a sampling module provided in an embodiment of the present application;

[0034] Figure 5 A circuit diagram of a comparison module provided in an embodiment of the present application;

[0035] Figure 6A circuit diagram of a voltage flip module provided in an embodiment of the present application;

[0036] Figure 7 A circuit diagram of a switch module provided in an embodiment of the present application;

[0037] Figure 8 This is a third structural schematic diagram of a photovoltaic inverter overvoltage protection circuit provided in an embodiment of the present application.

[0038] Figure numerals: 10 - photovoltaic inverter overvoltage protection circuit; 110 - sampling module; 111 - adjustment unit; 112 - amplification unit; 120 - comparison module; 121 - reference voltage adjustment unit; 130 - voltage flip module; 140 - switch module; 150 - input module; 151 - first interface; 152 - second interface; 153 - filtering unit; 160 - processor. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0040] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0041] In the description of this application, it should be noted that relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium.

[0042] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0043] As mentioned in the background technology, during the actual use of photovoltaic inverters, factors such as weather and light intensity may cause the input of the photovoltaic inverter to overvoltage, causing key components in the photovoltaic inverter to fail, resulting in the photovoltaic inverter being unable to operate and causing huge losses.

[0044] Therefore, how to quickly and easily protect key components in a photovoltaic inverter when input overvoltage occurs is a technical problem that needs to be solved urgently by those skilled in the art.

[0045] To solve the above problems, see Figure 1 An embodiment of the present application provides a photovoltaic inverter overvoltage protection circuit 10, which includes a sampling module 110, a comparison module 120, a voltage flip module 130 and a switch module 140.

[0046] The input end of the switch module 140 and the input end of the sampling module 110 are both used to receive the photovoltaic panel input voltage PV, and the output end of the switch module 140 is connected to the input end of the boost module. The output end of the sampling module 110 is connected to the comparison module 120 and the voltage flip module 130 in sequence, and the output end of the voltage flip module 130 is connected to the control end of the switch module 140.

[0047] The sampling module 110 is used to output a sampled voltage to the comparison module 120 according to the received photovoltaic panel input voltage PV. The comparison module 120 is used to compare the sampled voltage with a reference voltage and output the comparison voltage to the voltage inversion module 130.

[0048] The voltage inversion module 130 is used to invert the received comparison voltage, thereby controlling the on and off of the switch module 140 with positive logic.

[0049] When the photovoltaic panel input voltage PV is normal, that is, the sampling voltage is less than the reference voltage, the comparison module 120 outputs a low level, and the voltage inversion module 130 outputs a high level to control the switch module 140 to turn on, supplying power to the subsequent boost module.

[0050] When the photovoltaic panel input voltage PV is over-voltage, that is, the sampling voltage is greater than the reference voltage, the comparison module 120 outputs a high level, and the voltage flip module 130 outputs a low level to control the switch module 140 to shut down, thereby quickly cutting off the voltage input of key components (for example, bus capacitors) in the boost module to prevent high voltage from damaging the key components.

[0051] Based on the above design, the comparison module 120 compares the sampled voltage with the preset reference voltage to detect whether the photovoltaic panel input voltage PV is over-voltage. The voltage output by the comparison module 120 is flipped by the voltage flip module 130 to control the on and off of the switch module 140 with positive logic, ensuring that when the photovoltaic panel input voltage PV is over-voltage, the voltage flip module 130 outputs a low level to quickly control the switch module 140 to turn off, stop the power supply to the subsequent boost module, and thus protect the key components in the photovoltaic inverter.

[0052] As an alternative implementation, see Figure 2 The photovoltaic inverter overvoltage protection circuit 10 further includes an input module 150. The input end of the input module 150 is connected to the photovoltaic solar panel, and the first output end of the input module 150 is respectively connected to the input end of the switch module 140 and the second input end of the sampling module 110. The second output end of the input module 150 is respectively connected to the first input end of the sampling module 110 and the input end of the boost module.

[0053] The first output terminal of the input module 150 is used to output the positive photovoltaic panel input voltage PV+, and the second output terminal of the input module 150 is used to output the negative photovoltaic panel input voltage PV-.

[0054] For the specific structure of the input module 150, please refer to Figure 3 In the embodiment of the present application, the input module 150 includes a first interface 151 and a second interface 152 , and the direct current generated by the photovoltaic solar panel is input to the photovoltaic inverter through the first interface 151 and the second interface 152 .

[0055] In order to prevent the input of surge current, in the embodiment of the present application, the input module 150 may further include a filter unit 153, the first interface 151 and the second interface 152 are both connected to the input end of the filter unit 153, and the photovoltaic panel input voltage PV is processed and output by the filter unit 153. The specific structure of the filter unit 153 is not limited.

[0056] Optionally, in the embodiment of the present application, the filtering unit 153 includes a first inductor L1, a second inductor L2 and a third capacitor C3. Both ends of the third capacitor C3 are respectively connected to the output ends of the first interface 151 and the second interface 152. The output end of the first interface 151 also outputs the positive photovoltaic panel input voltage PV+ through the first inductor L1, and the output end of the second interface 152 also outputs the negative photovoltaic panel input voltage PV- through the second inductor L2.

[0057] The sampling module 110 receives the positive photovoltaic panel input voltage PV+ and the negative photovoltaic panel input voltage PV-, and outputs the sampled voltage to the comparison module 120. The specific structure of the sampling module 110 is as follows: Figure 4As shown, in the embodiment of the present application, the sampling module 110 includes an adjustment unit 111 and an amplification unit 112 .

[0058] Among them, the first input terminal and the second input terminal of the adjustment unit 111 are respectively connected to the second output terminal and the first output terminal of the input module 150, the first output terminal and the second output terminal of the adjustment unit 111 are respectively connected to the first input terminal and the second input terminal of the amplification unit 112, and the output terminal S_VPV of the amplification unit 112 is connected to the input terminal of the comparison module 120.

[0059] Specifically, the regulating unit 111 includes a plurality of first regulating resistors RA and a plurality of second regulating resistors RB. The plurality of first regulating resistors RA are sequentially connected in series between the second output terminal of the input module 150 and the first input terminal of the amplifying unit 112, and the plurality of second regulating resistors RB are sequentially connected in series between the first output terminal of the input module 150 and the second input terminal of the amplifying unit 112.

[0060] Optionally, the number of the plurality of first regulating resistors RA is the same as the number of the plurality of second regulating resistors RB, and the resistance values ​​of the plurality of first regulating resistors RA and the plurality of second regulating resistors RB are the same.

[0061] The amplifying unit 112 includes an amplifier U1, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7 and a first capacitor C1. The inverting input terminal of the amplifier U1 is connected to one end of the fourth resistor R4, the fifth resistor R5 and the first capacitor C1 respectively, and the other end of the fourth resistor R4 is connected to the first output terminal of the adjusting unit 111. The non-inverting input terminal of the amplifier U1 is connected to one end of the sixth resistor R6 and the seventh resistor R7 respectively, the other end of the sixth resistor R6 is connected to the second output terminal of the adjusting unit 111, and the other end of the seventh resistor R7 is grounded. The output terminal S_VPV of the amplifier U1 is connected to the other end of the fifth resistor R5, the other end of the first capacitor C1 and the input terminal of the comparison module 120 respectively.

[0062] In addition, the sampling voltage V output by amplifier U1 OUT =[R5 / (R4+xRA)]*(V PV+ -V PV- )=[R5 / (R4+xRA)]*V PV . Wherein, x is the number of the first adjustment resistors RA.

[0063] When the photovoltaic panel input voltage PV is greater than the overvoltage voltage, it indicates that the photovoltaic inverter input is overvoltage. When the photovoltaic panel input voltage PV is equal to the overvoltage voltage, the sampling voltage V output by the amplifier U1 is OUT That is the reference voltage Vref.

[0064] See also Figure 5 , Figure 5 The circuit diagram of a comparison module 120 provided in an embodiment of the present application is shown. The comparison module 120 includes a comparator U2, a reference voltage adjustment unit 121, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10 and a second capacitor C2.

[0065] The in-phase input terminal of the comparator U2 is connected to one end of the eighth resistor R8 and the ninth resistor R9 respectively, the other end of the eighth resistor R8 is connected to the output terminal S_VPV of the sampling module 110, and the other end of the ninth resistor R9 is grounded. The inverting input terminal of the comparator U2 is connected to the reference voltage adjustment unit 121.

[0066] The reference voltage adjustment unit 121 can adjust the inverting input voltage V of the comparator U2. - (ie, the size of the reference voltage Vref).

[0067] Specifically, in the embodiment of the present application, the reference voltage adjustment unit 121 includes an eleventh resistor R11 and a twelfth resistor R12. The inverting input terminal of the comparator U2 is connected to one end of the eleventh resistor R11 and the twelfth resistor R12 respectively, the other end of the eleventh resistor R11 is connected to the reference power supply V1, and the other end of the twelfth resistor R12 is grounded.

[0068] Among them, the inverting input voltage of comparator U2 is V - =[R12 / (R11+R12)]*V1.

[0069] It should be noted that when the photovoltaic panel input voltage PV is equal to the overvoltage voltage, the sampling voltage V output by the amplification unit 112 is OUT =Voltage of the inverting input terminal of comparator U2 - =reference voltage Vref.

[0070] The output terminal RY-EN of the comparator U2 is respectively connected to one end of the tenth resistor R10, one end of the second capacitor C2 and the input end of the voltage flip module 130, the other end of the tenth resistor R10 is connected to the reference power supply V1, and the other end of the second capacitor C2 is grounded.

[0071] When the sampling voltage V OUT When the sampling voltage V OUT When it is less than the reference voltage Vref, the comparison voltage output by the comparator U2 is pulled down to a low level.

[0072] To better understand the working principle of the sampling module 110 and the comparison module 120, please refer to Figure 4 and Figure 5Assuming that the overvoltage is 1050V, the number of the multiple first adjustment resistors RA and the number of the multiple second adjustment resistors RB are both 8, and the resistance values ​​of the multiple first adjustment resistors RA and the multiple second adjustment resistors RB are both 1MΩ. The fourth resistor R4 = 10KΩ, the fifth resistor R5 = 20KΩ, the eleventh resistor R11 = 10KΩ, the twelfth resistor R12 = 39KΩ, and the reference power supply voltage V1 = 3.3V.

[0073] When the photovoltaic panel input voltage V PV >1050V, the sampling voltage V output by amplifier U1 OUT >[20K / (10K+8M)]*1050=2.62V, the voltage V at the inverting input of comparator U2 - =[39K / (10K+39K)]*3.3=2.62V.

[0074] This is equivalent to the voltage at the non-inverting input terminal of the comparator U2 being greater than the voltage at the inverting input terminal of the comparator U2 (ie, the reference voltage Vref), and the comparison voltage outputted by the output terminal RY-EN of the comparator U2 is pulled up to 3.3V by the tenth resistor R10.

[0075] Similarly, when the photovoltaic panel input voltage V PV When <1050V, the voltage at the non-inverting input terminal of the comparator U2 is less than the voltage at the inverting input terminal of the comparator U2, and the comparison voltage outputted by the output terminal RY-EN of the comparator U2 is 0V.

[0076] Optionally, in order to make the output signal more stable, in the embodiment of the present application, the amplification unit 112 further includes a first filter capacitor, which is connected in parallel with the seventh resistor R7. The comparison module 120 further includes a second filter capacitor and a third filter capacitor, which is connected in parallel with the ninth resistor R9, and the third filter capacitor is connected in parallel with the twelfth resistor R12.

[0077] See also Figure 6 , Figure 6 A circuit diagram of a voltage flip module 130 provided in an embodiment of the present application. In the embodiment of the present application, the voltage flip module 130 includes a second N-type switch tube Q2, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15 and a sixteenth resistor R16.

[0078] The control end of the second N-type switch tube Q2 is respectively connected to one end of the thirteenth resistor R13 and the fourteenth resistor R14, the other end of the thirteenth resistor R13 is connected to the output end RY-EN of the comparison module 120, and the other end of the fourteenth resistor R14 and the second port of the second N-type switch tube Q2 are both grounded. The first port of the second N-type switch tube Q2 is respectively connected to one end of the fifteenth resistor R15 and the sixteenth resistor R16, the other end of the fifteenth resistor R15 is connected to the reference power supply V1, and the other end of the sixteenth resistor R16 is connected to the control end RY-D of the switch module 140.

[0079] When the comparison module 120 outputs a low level, the second N-type switch tube Q2 is turned off, and the output end of the voltage flip module 130 outputs a high level. When the comparison module 120 outputs a high level, the second N-type switch tube Q2 is turned on, and the output end of the voltage flip module 130 outputs a low level and is transmitted to the control end RY-D of the switch module 140.

[0080] In the embodiment of the present application, the specific structure of the switch module 140 is as follows: Figure 7 As shown, the switch module 140 includes a first N-type switch tube Q1, a first resistor R1, a second resistor R2, a third resistor R3 and a relay RLY. One end of the first resistor R1 is connected to the first output end of the input module 150, and the other end of the first resistor R1 is connected to the input end of the boost module.

[0081] The relay RLY includes a contact switch and a relay coil, the contact switch is connected in parallel with the first resistor R1, one end of the relay coil is connected to the power supply V2, and the other end of the relay coil is connected to the first port of the first N-type switch tube Q1. The control end of the first N-type switch tube Q1 is respectively connected to one end of the second resistor R2 and the third resistor R3, the other end of the second resistor R2 (i.e., the control end RY-D of the switch module 140) is connected to the output end of the voltage flip module 130, and the other end of the third resistor R3 and the second port of the first N-type switch tube Q1 are both grounded.

[0082] When the voltage flip module 130 outputs a high level, the first N-type switch tube Q1 is turned on, the relay coil is energized, and the contact switch is closed. When the voltage flip module 130 outputs a low level, the first N-type switch tube Q1 is turned off, the relay coil is de-energized, and the contact switch is opened.

[0083] Optionally, the first resistor R1 is a PTC resistor, and the first N-type switch tube Q1 and the second N-type switch tube Q2 may be triodes or MOS tubes.

[0084] The first resistor R1 and the relay RLY constitute a soft start unit. When the photovoltaic panel input voltage PV is just connected to the photovoltaic inverter, the first resistor R1 is at room temperature and its resistance is small. If the comparison module 120 detects that the photovoltaic panel input voltage PV is normal, the positive photovoltaic panel input voltage PV+ is limited by the first resistor R1 to supply power to the boost module.

[0085] After a period of time, the temperature of the first resistor R1 increases, and its resistance value increases. If the comparison module 120 detects that the photovoltaic panel input voltage PV reaches a reasonable range (i.e., the photovoltaic panel input voltage PV < overvoltage), the relay RLY is turned on, and the positive photovoltaic panel input voltage PV+ is subsequently powered to the load through the relay RLY. If the comparison module 120 detects that the photovoltaic panel input voltage PV is overvoltage, the relay RLY is disconnected, cutting off the power supply to the boost module, protecting the key components in the boost circuit from damage, and making a corresponding fault alarm.

[0086] As a possible implementation, see Figure 8 In the embodiment of the present application, the photovoltaic inverter overvoltage protection circuit 10 further includes a processor 160. The first port S_VPV and the second port BOOST of the processor 160 are respectively connected to the output end of the sampling module 110 and the input end of the boost module, and the processor 160 is used to adjust the boost value of the boost module according to the size of the sampled voltage.

[0087] The third port RY-EN and the fourth port RY-D of the processor 160 are connected to the output end of the comparison module 120 and the control end of the switch module 140 respectively. The processor 160 is used to control the on and off of the switch module 140 according to the comparison voltage.

[0088] In addition, when the processor 160 detects that the subsequent load is in a state of overload, short circuit, failure, etc., the switch module 140 can be directly controlled to be turned off through the fourth port RY-D.

[0089] Furthermore, an embodiment of the present application also provides a photovoltaic system, which includes the photovoltaic inverter overvoltage protection circuit 10 as described in any of the above-mentioned embodiments.

[0090] In summary, the present application provides a photovoltaic inverter overvoltage protection circuit and a photovoltaic system. The photovoltaic panel input voltage is received by a sampling module, and the sampled voltage is output to a comparison module. The sampling voltage is compared with a preset reference voltage by the comparison module to detect whether the photovoltaic panel input voltage is overvoltage. The voltage output by the comparison module is flipped by a voltage flip module, and the on and off of the switch module is controlled by positive logic to ensure that when the photovoltaic panel input voltage is overvoltage, the voltage flip module outputs a low level to quickly control the switch module to turn off, and stop the power supply to subsequent loads, thereby protecting the key components in the photovoltaic inverter.

[0091] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0092] It will be apparent to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, and that the present application can be implemented in other specific forms without departing from the spirit or essential features of the present application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present application. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A photovoltaic inverter overvoltage protection circuit, characterized in that: The circuit includes a sampling module, a comparison module, a voltage flip module and a switch module; The input end of the switch module and the input end of the sampling module are both used to receive the photovoltaic panel input voltage, and the output end of the switch module is connected to the input end of the boost module; the output end of the sampling module is connected to the comparison module and the voltage flip module in sequence, and the output end of the voltage flip module is connected to the control end of the switch module; The sampling module is used to output a sampling voltage to the comparison module according to the received photovoltaic panel input voltage; The comparison module is used to compare the sampled voltage with the reference voltage, and output the comparison voltage to the voltage inversion module; The voltage flipping module is used to flip the comparison voltage; When the sampling voltage is greater than the reference voltage, the voltage flip module outputs a low level to control the switch module to turn off.

2. The photovoltaic inverter overvoltage protection circuit according to claim 1, characterized in that: The circuit also includes an input module, the input end of the input module is connected to the photovoltaic panel, the first output end of the input module is respectively connected to the input end of the switch module and the second input end of the sampling module, and the second output end of the input module is respectively connected to the input end of the boost module and the first input end of the sampling module; The first output terminal of the input module is used to output a positive photovoltaic panel input voltage, and the second output terminal of the input module is used to output a negative photovoltaic panel input voltage.

3. The photovoltaic inverter overvoltage protection circuit according to claim 2, characterized in that: The switch module includes a first N-type switch tube, a first resistor, a second resistor, a third resistor and a relay; one end of the first resistor is connected to the first output end of the input module, and the other end of the first resistor is connected to the input end of the boost module; The relay includes a contact switch and a relay coil, the contact switch is connected in parallel with the first resistor, one end of the relay coil is connected to the power supply, the other end of the relay coil is connected to the first port of the first N-type switch tube, the control end of the first N-type switch tube is respectively connected to one end of the second resistor and the third resistor, the other end of the second resistor is connected to the output end of the voltage flip module, and the other end of the third resistor and the second port of the first N-type switch tube are both grounded.

4. The photovoltaic inverter overvoltage protection circuit according to claim 2, characterized in that: The sampling module includes an adjustment unit and an amplification unit, wherein the first input terminal and the second input terminal of the adjustment unit are respectively connected to the second output terminal and the first output terminal of the input module, the first output terminal and the second output terminal of the adjustment unit are respectively connected to the first input terminal and the second input terminal of the amplification unit, and the output terminal of the amplification unit is connected to the input terminal of the comparison module.

5. The photovoltaic inverter overvoltage protection circuit according to claim 4, characterized in that: The regulating unit comprises a plurality of first regulating resistors and a plurality of second regulating resistors, wherein the plurality of first regulating resistors are sequentially connected in series between the second output terminal of the input module and the first input terminal of the amplifying unit; A plurality of second regulating resistors are sequentially connected in series between the first output terminal of the input module and the second input terminal of the amplifying unit; The amplification unit includes an amplifier, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and a first capacitor; the inverting input terminal of the amplifier is respectively connected to one end of the fourth resistor, the fifth resistor and the first capacitor, the other end of the fourth resistor is connected to the first output terminal of the adjustment unit, and the output terminal of the amplifier is respectively connected to the other end of the fifth resistor, the other end of the first capacitor and the input terminal of the comparison module; The in-phase input terminal of the amplifier is connected to one end of the sixth resistor and the seventh resistor respectively, the other end of the sixth resistor is connected to the second output terminal of the adjustment unit, and the other end of the seventh resistor is grounded.

6. The photovoltaic inverter overvoltage protection circuit according to claim 1, characterized in that: The comparison module includes a comparator, a reference voltage adjustment unit, an eighth resistor, a ninth resistor, a tenth resistor and a second capacitor; the non-inverting input terminal of the comparator is connected to one end of the eighth resistor and the ninth resistor respectively, the other end of the eighth resistor is connected to the output end of the sampling module, and the other end of the ninth resistor is grounded; The inverting input end of the comparator is connected to the reference voltage adjustment unit, the output end of the comparator is respectively connected to one end of the tenth resistor, one end of the second capacitor and the input end of the voltage flip module, the other end of the tenth resistor is connected to the reference power supply, and the other end of the second capacitor is grounded.

7. The photovoltaic inverter overvoltage protection circuit according to claim 6, characterized in that: The reference voltage adjustment unit includes an eleventh resistor and a twelfth resistor, the inverting input terminal of the comparator is connected to one end of the eleventh resistor and the twelfth resistor respectively, the other end of the eleventh resistor is connected to the reference power supply, and the other end of the twelfth resistor is grounded.

8. The photovoltaic inverter overvoltage protection circuit according to claim 1, characterized in that: The voltage flip module includes a second N-type switch tube, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor and a sixteenth resistor; The control end of the second N-type switch tube is respectively connected to one end of the thirteenth resistor and the fourteenth resistor, the other end of the thirteenth resistor is connected to the output end of the comparison module, and the other end of the fourteenth resistor and the second port of the second N-type switch tube are both grounded; The first port of the second N-type switch tube is connected to one end of the fifteenth resistor and the sixteenth resistor respectively, the other end of the fifteenth resistor is connected to the reference power supply, and the other end of the sixteenth resistor is connected to the control end of the switch module.

9. The photovoltaic inverter overvoltage protection circuit according to claim 1, characterized in that: The circuit also includes a processor, wherein a first port and a second port of the processor are respectively connected to an output end of the sampling module and an input end of the boost module, and the processor is used to adjust a boost value of the boost module according to the size of the sampling voltage; The third port and the fourth port of the processor are connected to the output end of the comparison module and the control end of the switch module respectively. The processor is also used to control the on and off of the switch module according to the comparison voltage.

10. A photovoltaic system, characterized in that: The photovoltaic system comprises the photovoltaic inverter overvoltage protection circuit according to any one of claims 1 to 9.

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