Anti-reverse connection circuit, control method, photovoltaic power supply system and photovoltaic air conditioner

Abstract

The present invention discloses an anti-reverse connection circuit, a control method, a photovoltaic power supply system and a photovoltaic air conditioner. The anti-reverse connection circuit includes a resistor sampling module, a logic judgment module and a controller connected in sequence; the resistor sampling module is connected to the interface between the photovoltaic string and the inverter, and is used to collect the positive voltage and the negative voltage at the interface, and generate a sampling signal based on the positive voltage and the negative voltage; the logic judgment module is used to generate a control signal according to the sampling signal; the controller is used to control the power on and off of the inverter according to the control signal. Through the present invention, the use of a voltage sensor for voltage sampling can be avoided, saving costs. At the same time, after the reverse connection, the controller can cut off the power supply of the inverter in time to improve safety.

Description

Technical Field

[0001] The present invention relates to the field of electronic power technology, and in particular to an anti-reverse connection circuit, a control method, a photovoltaic power supply system and a photovoltaic air conditioner. Background Art

[0002] In the photovoltaic power supply system, the photovoltaic strings need to be connected to the DC bus of the inverter. However, the positive and negative terminals of the photovoltaic strings may be reversed. If reversed, it will cause a short circuit and cause great damage to the inverter. Therefore, the interface between the photovoltaic strings and the inverter must be reversed. The current reverse connection detection scheme generally uses a voltage sensor to detect whether it is reversed, which is costly and can only detect reverse connection anomalies, but cannot directly handle the reverse connection anomalies, resulting in untimely handling and affecting the safety of the inverter.

[0003] With regard to the problems of high cost and low safety of the reverse connection protection scheme of photovoltaic strings in the prior art, no effective solution has been proposed so far. Summary of the invention

[0004] The embodiments of the present invention provide a reverse connection prevention circuit, a control method, a photovoltaic power supply system and a photovoltaic air conditioner to solve the problems of high cost and low safety of the reverse connection prevention scheme of photovoltaic strings in the prior art.

[0005] In order to solve the above technical problems, the present invention provides an anti-reverse connection circuit, which is applied to a photovoltaic power supply system. The circuit includes a resistance sampling module, a logic judgment module, and a controller connected in sequence;

[0006] The resistance sampling module is connected to the interface between the photovoltaic string and the inverter, and is used to collect the positive voltage and the negative voltage at the interface, and generate a sampling signal based on the positive voltage and the negative voltage;

[0007] The logic judgment module is used to generate a control signal according to the sampling signal;

[0008] The controller is used to control the power on and off of the frequency converter according to the control signal.

[0009] Furthermore, the resistance sampling module includes:

[0010] A first sampling unit, whose input end is connected to the positive terminal at the interface between the photovoltaic string and the inverter, for collecting the positive voltage and generating a first sampling signal;

[0011] The second sampling unit has an input end connected to the negative electrode terminal at the interface between the photovoltaic string and the inverter, and is used to collect the negative electrode voltage and generate a second sampling signal.

[0012] Furthermore, the first sampling unit includes:

[0013] a first resistor, a first end of which is connected to the positive terminal, and a second end of which is connected to the logic judgment module;

[0014] A second resistor has a first end connected between the positive terminal and the logic judgment module, and a second end connected to ground.

[0015] Furthermore, the second sampling unit includes:

[0016] a third resistor, a first end of which is connected to the negative terminal, and a second end of which is connected to the logic judgment module;

[0017] A fourth resistor has a first end connected between the negative terminal and the logic judgment module, and a second end connected to the ground.

[0018] Furthermore, the logic judgment module is specifically used for:

[0019] When the first sampling signal is a high level signal and the second sampling signal is a low level signal, outputting a low level signal;

[0020] When the first sampling signal is a low level signal and the second sampling signal is a high level signal, a high level signal is output.

[0021] Furthermore, the logic judgment module includes:

[0022] A first NAND gate, whose first input terminal is connected to the output terminal of the first sampling unit, whose second input terminal is grounded, and whose output terminal is connected to a third NAND gate; used to output a high level signal when the first sampling signal is a high level signal, and output a high level signal when the first sampling signal is a low level signal;

[0023] A second NAND gate, whose first input terminal is connected to the output terminal of the second sampling unit, whose second input terminal is connected to the first voltage source, and whose output terminal is connected to the third NAND gate; used to output a high level signal when the first sampling signal is a low level signal, and output a low level signal when the second sampling signal is a high level signal;

[0024] The third NAND gate has a first end connected to the output end of the first NAND gate, a second end connected to the output end of the second NAND gate, and an output end connected to the controller; it is used to output a low level signal to the controller when the first NAND gate outputs a high level signal and the second NAND gate outputs a high level signal; it is used to output a high level signal to the controller when the first NAND gate outputs a high level signal and the second NAND gate outputs a low level signal.

[0025] Furthermore, the circuit further comprises:

[0026] The voltage conversion module is arranged between the logic judgment module and the controller, and is used to convert the high voltage signal into a low voltage signal based on the control signal output by the logic judgment module, and output it to the controller.

[0027] The present invention also provides a photovoltaic power supply system, comprising a photovoltaic string and a frequency converter, wherein the photovoltaic power supply system also comprises the above-mentioned anti-reverse connection circuit.

[0028] Furthermore, the photovoltaic power supply system further comprises:

[0029] A controllable switch component, which is a normally closed switch, used to close or open under the control of the controller, thereby controlling the on and off of the frequency converter;

[0030] The controller is specifically used to: when a high-level signal is input to its input end, control the controllable switch component to be disconnected, thereby controlling the inverter to be powered off; when a low-level signal is input to its input end, control the controllable switch component to be closed, thereby controlling the inverter to be powered on.

[0031] Furthermore, the controllable switch assembly comprises:

[0032] The first switch group is arranged between the positive terminal of the photovoltaic string and the positive terminal of the inverter, and is used to control the connection and disconnection between the positive terminal of the photovoltaic string and the positive terminal of the inverter.

[0033] The second switch group is arranged between the negative terminal of the photovoltaic string and the negative terminal of the inverter, and is used to control the connection and disconnection between the negative terminal of the photovoltaic string and the negative terminal of the inverter.

[0034] The present invention also provides a photovoltaic air conditioner, comprising the above-mentioned photovoltaic power supply system.

[0035] The present invention also provides an anti-reverse connection control method, the method comprising:

[0036] Acquire a control signal; wherein the control signal is generated based on a sampling signal at an interface between a photovoltaic string and a frequency converter, and the sampling signal is generated based on a positive voltage and a negative voltage at the interface;

[0037] The inverter is controlled to be powered on and off according to the control signal.

[0038] Further, controlling the power on and off of the frequency converter according to the control signal comprises:

[0039] If the control signal is a low level signal, the frequency converter is controlled to be powered on;

[0040] If the control signal is a high level signal, the frequency converter is controlled to be powered off.

[0041] The present invention also provides a computer-readable storage medium on which a computer program is stored, and when the program is executed by a processor, the above-mentioned anti-reverse connection control method is implemented.

[0042] By applying the technical solution of the present invention, the resistance sampling module collects the positive voltage and the negative voltage at the interface between the photovoltaic string and the inverter and generates a sampling signal. The logic judgment module generates a control signal based on the sampling signal. The controller controls the power on and off of the inverter according to the control signal, thereby eliminating the need for a voltage sensor to perform voltage sampling and saving costs. At the same time, after detecting reverse connection, the controller can promptly cut off the power supply of the inverter to improve safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a structural diagram of an anti-reverse connection circuit according to an embodiment of the present invention;

[0044] Figure 2 is a structural diagram of a reverse connection protection circuit according to another embodiment of the present invention;

[0045] Figure 3 A diagram showing the connection relationship between the anti-reverse connection circuit and the photovoltaic power supply system according to an embodiment of the present invention;

[0046] Figure 4 is an input and output waveform diagram of the third NAND gate when the positive and negative terminals are connected correctly according to an embodiment of the present invention;

[0047] Figure 5 is an input and output waveform diagram of the third NAND gate when the positive and negative terminals are connected incorrectly according to an embodiment of the present invention;

[0048] Figure 6 Flow chart of the anti-reverse connection control method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0051] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0052] It should be understood that although the terms first, second, etc. may be used to describe the sampling units in the embodiments of the present invention, the sampling units should not be limited to these terms. These terms are only used to distinguish the sampling units arranged at different positions. For example, without departing from the scope of the embodiments of the present invention, the first sampling unit may also be referred to as the second sampling unit, and similarly, the second sampling unit may also be referred to as the first sampling unit.

[0053] As used herein, the words "if" and "if" may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0054] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0055] The optional embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0056] Example 1

[0057] This embodiment provides an anti-reverse connection circuit, which is applied to a photovoltaic power supply system. Figure 1 is a structural diagram of an anti-reverse connection circuit according to an embodiment of the present invention, as shown in Figure 1 As shown, the anti-reverse connection circuit includes a resistance sampling module 10, a logic judgment module 20, and a controller 30 connected in sequence;

[0058] The resistance sampling module 10, whose input end is connected to the interface between the photovoltaic string and the inverter, is used to collect the positive voltage and the negative voltage at the interface, and generate a sampling signal based on the positive voltage and the negative voltage at the interface; the logic judgment module 20, whose input end is connected to the resistance sampling module 10, is used to generate a control signal according to the sampling signal; the controller 30, whose input end is connected to the logic judgment module 20, is used to control the power on and off of the inverter according to the control signal.

[0059] In actual applications, the interface of the photovoltaic string includes a positive terminal and a negative terminal, which are connected one-to-one with the positive terminal and the negative terminal of the inverter interface to form a positive terminal and a negative terminal. However, there is a risk of misconnection between the two sets of terminals.

[0060] The anti-reverse connection circuit of this embodiment collects the positive voltage and negative voltage at the interface between the photovoltaic string and the inverter through the resistance sampling module 10 and generates a sampling signal, generates a control signal based on the sampling signal through the logic judgment module 20, and controls the power on and off of the inverter according to the control signal through the controller 30, which can avoid using a voltage sensor for voltage sampling and save costs. At the same time, after reverse connection, the controller 30 can cut off the power supply of the inverter in time to improve safety.

[0061] Example 2

[0062] This embodiment provides another anti-reverse connection circuit. Figure 2 FIG. 1 is a structural diagram of an anti-reverse connection circuit according to another embodiment of the present invention. The positive and negative voltages at the interface between the photovoltaic string and the inverter are relatively large DC voltages. Directly inputting the voltage into the post-stage logic judgment module 20 will cause the input voltage of the logic judgment module 20 to be too large. In order to solve this problem, Figure 2 As shown, the resistance sampling module 10 includes: a first sampling unit 101, whose input end is connected to the positive terminal at the interface between the photovoltaic string and the inverter, for collecting the positive voltage at the interface between the photovoltaic string and the inverter, and generating a first sampling signal; Figure 2 As shown, the first sampling unit 101 includes: a first resistor R1, a first end of which is connected to the positive terminal at the interface between the photovoltaic string and the inverter, and a second end of which is connected to the logic judgment module 20; a second resistor R2, a first end of which is connected between the positive terminal at the interface between the photovoltaic string and the inverter and the logic judgment module 20, and a second end of which is grounded. The larger DC voltage can be converted into a safe input voltage of the subsequent logic judgment module 20 by dividing the voltage between the first resistor R1 and the second resistor R2.

[0063] The second sampling unit 102 has an input end connected to the negative terminal at the interface between the photovoltaic string and the inverter, and is used to collect the negative voltage at the interface between the photovoltaic string and the inverter and generate a second sampling signal. Figure 2As shown, the second sampling unit 102 includes: a third resistor R3, a first end of which is connected to the negative terminal at the interface between the photovoltaic string and the inverter, and a second end of which is connected to the logic judgment module 20; a fourth resistor R4, a first end of which is connected between the negative terminal at the interface between the photovoltaic string and the inverter and the logic judgment module 20, and a second end of which is grounded. Similarly, the voltage division of the first resistor R1 and the second resistor R2 can convert a larger DC voltage into a safe input voltage of the subsequent logic judgment module 20.

[0064] It should be noted that the above embodiments are only illustrative of the structure of the resistance sampling module of the present invention. Those skilled in the art may improve the structure of the resistance sampling module according to the concept of the present invention. For example, the first resistor R1 may be changed to two resistors with smaller resistance values ​​connected in series, or two resistors with larger resistance values ​​connected in parallel, or more resistors may be connected in series or in parallel to form a voltage divider network to realize the voltage sampling function.

[0065] In order to finally generate a control signal based on the sampling signal to control the power on and off of the inverter, the logic judgment module 20 is specifically used to: when the first sampling signal is a high-level signal and the second sampling signal is a low-level signal, that is, when the positive and negative terminals of the photovoltaic string and the inverter are not reversed, output a low-level signal to control the inverter to power on; when the first sampling signal is a low-level signal and the second sampling signal is a high-level signal, that is, when the positive and negative terminals of the photovoltaic string and the inverter are reversed, output a high-level signal to control the inverter to power off to avoid safety hazards.

[0066] In order to realize the conversion of the down-sampled signal into the control signal, the above-mentioned logic judgment module 20 includes: a first NAND gate U1, whose first input end is connected to the output end of the first sampling unit 101, whose second input end is grounded, and whose output end is connected to the third NAND gate U3; when the first sampling signal is a high-level signal, it outputs a high-level signal, and when the first sampling signal is a low-level signal, it outputs a high-level signal; a second NAND gate U2, whose first input end is connected to the output end of the second sampling unit 102, whose second input end is connected to the first voltage source, and whose output end is connected to the third NAND gate U3; when the first sampling signal is a high-level signal, it outputs a high-level signal; When the sampling signal is a low-level signal, a high-level signal is output, and when the second sampling signal is a high-level signal, a low-level signal is output; a third NAND gate U3, a first end of which is connected to the output end of the first NAND gate U1, a second end of which is connected to the output end of the second NAND gate U2, and an output end of which is connected to the controller 30; used for outputting a low-level signal to the controller 30 when the first NAND gate U1 outputs a high-level signal and the second NAND gate U2 outputs a high-level signal; and outputting a high-level signal to the controller 30 when the first NAND gate U1 outputs a high-level signal and the second NAND gate U2 outputs a low-level signal.

[0067] It should be noted that the logic judgment module 20 in the present invention is not limited to realizing logic judgment through a combination of several NAND gates, but can also realize the above function through a combination of comparators.

[0068] Since the controller 30 performs logic control through the control chip, the input voltage of the control chip cannot be too large. In order to limit the input voltage of the controller 30, Figure 2 As shown, the anti-reverse connection circuit further includes: a voltage conversion module 40, which is arranged between the logic judgment module 20 and the controller 30, and is used to convert the high voltage signal into a low voltage signal based on the control signal output by the logic judgment module 20, and output it to the controller 30. The level conversion module is composed of a level conversion chip, which can convert the +5V signal into a +3.3V signal and directly input it into the controller 30.

[0069] Figure 3 is a connection diagram of an anti-reverse connection circuit and a photovoltaic power supply system according to an embodiment of the present invention, as shown in Figure 3 As shown, the above-mentioned photovoltaic power supply system also includes: a controllable switch component QF1, which is a normally closed switch, used to close or open under the control of the controller 30, thereby controlling the power on and off of the inverter; the controller 30 is specifically used to: when a high-level signal is input at its input end, control the controllable switch component to open, thereby controlling the power off of the inverter; when a low-level signal is input at its input end, control the controllable switch component to close, and control the inverter to power on.

[0070] If the controllable switch component is directly controlled to conduct, the DC bus voltage value will fluctuate greatly in an instant. Figure 3 As shown, the photovoltaic power supply system further includes:

[0071] The first contactor KM1 and the first charging resistor R5 are arranged between the positive terminal of the photovoltaic string and the positive terminal of the inverter, and the second contactor KM2 and the second charging resistor R6 are arranged between the positive terminal of the photovoltaic string and the positive terminal of the inverter. After the inverter is powered on, the first contactor KM1 and the second contactor KM2 are closed, and the DC bus is charged through the first charging resistor R5 and the second charging resistor R6. When the DC bus is charged to a preset voltage value, the first contactor KM1 and the second contactor KM2 are disconnected, and the controllable switch component QF1 is closed. Specifically, the controllable switch component QF1 includes:

[0072] The first switch group is arranged between the positive terminal of the photovoltaic string and the positive terminal of the inverter, and includes a first contact N, a second contact N1, a third contact 1 and a fourth contact 2. The connection and disconnection of the positive terminal of the photovoltaic string and the positive terminal of the inverter are controlled by closing and opening the first contact N and the second contact N1, and closing and opening the third contact 1 and the fourth contact.

[0073] The second switch group is arranged between the negative terminal of the photovoltaic string and the negative terminal of the inverter, and includes a fifth contact 3, a sixth contact 4, a seventh contact 5 and an eighth contact 6. The connection and disconnection of the negative terminal of the photovoltaic string and the negative terminal of the inverter are controlled by closing and opening of the fifth contact 3 and the sixth contact 4, and closing and opening of the seventh contact 5 and the eighth contact 6.

[0074] In the specific implementation, the logic judgment module is composed of three NAND gates. The characteristic of the NAND gate is that when the input is all high level 1, the output is low level 0, so this characteristic can be used for logic judgment. The positive terminal at the interface between the photovoltaic string and the inverter is connected to the first input terminal of the first NAND gate U1, the second input terminal of the first NAND gate U1 is grounded, the negative terminal is connected to the first input terminal of the second NAND gate U2, the second input terminal of the second NAND gate U2 is connected to the 5V voltage source, and the output terminals of the first NAND gate U1 and the second NAND gate U2 are connected to the two input terminals of the third NAND gate U3. Therefore, when the positive and negative terminals of the photovoltaic string and the inverter are connected correctly, the first NAND gate U1 outputs a high level 1, the second NAND gate U2 outputs a high level 1, and the third NAND gate U3 outputs a low level 0; when the positive and negative terminals of the photovoltaic string and the inverter are connected incorrectly, the first NAND gate U1 outputs a high level 1, the second NAND gate U2 outputs a low level 0, and the third NAND gate U3 outputs a high level 1.

[0075] Figure 4 3 is an input and output waveform diagram of the third NAND gate when the positive and negative terminals are connected correctly according to an embodiment of the present invention. When the inverter is connected to the DC, the inverter power supply is turned on, and the controller 30 starts to perform reverse connection detection, such as Figure 4 As shown, when the photovoltaic string is correctly connected to the positive and negative terminals of the inverter, the third NAND gate U3 outputs a low level 0, and the controller 30 inputs a low level 0, that is, the controller 30 cannot detect an error signal, and the inverter can be powered on normally.

[0076] Figure 5 : is an input and output waveform diagram of the third NAND gate when the positive and negative terminals are connected incorrectly according to an embodiment of the present invention, such as Figure 5 As shown, when the photovoltaic string is incorrectly connected to the positive and negative terminals of the inverter, the third NAND gate U3 outputs a high level 1, and the controller 30 inputs a high level 1. The controller 30 detects an error signal, reports a fault signal, cuts off the power supply of the inverter, and protects the inverter.

[0077] Example 3

[0078] This embodiment provides a photovoltaic power supply system, including a photovoltaic string and a frequency converter. The photovoltaic power supply system also includes the anti-reverse connection circuit in the above embodiment, which is used to reduce costs and improve system safety.

[0079] Example 4

[0080] This embodiment provides a photovoltaic air conditioner, including the photovoltaic power supply system in the above embodiment, which is used to reduce the cost of the entire photovoltaic air conditioner and improve the safety of the entire photovoltaic air conditioner.

[0081] Example 5

[0082] This embodiment provides an anti-reverse connection control method. Figure 6 Flow chart of the anti-reverse connection control method according to an embodiment of the present invention. Figure 6 As shown, the method includes:

[0083] S101, obtaining a control signal; wherein the control signal is generated based on a sampling signal at an interface between a photovoltaic string and a frequency converter, and the sampling signal is generated based on a positive voltage and a negative voltage at the interface.

[0084] In specific implementation, a resistor sampling module is used, whose input end is connected to the interface between the photovoltaic string and the inverter, to collect the positive voltage and the negative voltage at the interface, and generate a sampling signal based on the positive voltage and the negative voltage at the interface between the photovoltaic string and the inverter; a logic judgment module, whose input end is connected to the resistor sampling module, is used to generate a control signal according to the sampling signal.

[0085] The resistance sampling module includes: a first sampling unit, whose input end is connected to the positive terminal at the interface between the photovoltaic string and the inverter, for collecting the positive voltage and generating a first sampling signal; the first sampling unit includes: a first resistor, whose first end is connected to the positive terminal at the interface between the photovoltaic string and the inverter, and whose second end is connected to the logic judgment module; a second resistor, whose first end is connected between the positive terminal at the interface between the photovoltaic string and the inverter and the logic judgment module, and whose second end is grounded. The larger DC voltage can be converted into a safe input voltage of the subsequent logic judgment module by voltage division between the first resistor and the second resistor.

[0086] The second sampling unit, whose input end is connected to the negative terminal at the interface between the photovoltaic string and the inverter, is used to collect the negative voltage at the interface between the photovoltaic string and the inverter and generate a second sampling signal. The second sampling unit includes: a third resistor, whose first end is connected to the negative terminal at the interface between the photovoltaic string and the inverter, and whose second end is connected to the logic judgment module; a fourth resistor, whose first end is connected between the negative terminal at the interface between the photovoltaic string and the inverter and the logic judgment module, and whose second end is grounded. Similarly, the voltage division of the first resistor and the second resistor can convert a larger DC voltage into a safe input voltage for the logic judgment module of the subsequent stage.

[0087] In order to finally generate a control signal based on the sampling signal to control the power on and off of the inverter, the logic judgment module is specifically used to: when the first sampling signal is a high-level signal and the second sampling signal is a low-level signal, that is, when the positive and negative terminals of the photovoltaic string and the inverter are not reversed, output a low-level signal to control the inverter to power on; when the first sampling signal is a low-level signal and the second sampling signal is a high-level signal, that is, when the positive and negative terminals of the photovoltaic string and the inverter are reversed, output a high-level signal to control the inverter to power off and avoid safety hazards.

[0088] In order to realize the conversion of the down-sampled signal into the control signal, the above-mentioned logic judgment module includes: a first NAND gate, whose first input end is connected to the output end of the first sampling unit, whose second input end is grounded, and whose output end is connected to the third NAND gate; when the first sampling signal is a high-level signal, the high-level signal is output, and when the first sampling signal is a low-level signal, the high-level signal is output; a second NAND gate, whose first input end is connected to the output end of the second sampling unit, whose second input end is connected to the first voltage source, and whose output end is connected to the third NAND gate; when the first sampling signal is a low-level signal, the high-level signal is output, and when the second sampling signal is a high-level signal, the low-level signal is output; a third NAND gate, whose first end is connected to the output end of the first NAND gate, whose second end is connected to the output end of the second NAND gate, and whose output end is connected to the controller; when the first NAND gate outputs a high-level signal and the second NAND gate outputs a high-level signal, the low-level signal is output to the controller; when the first NAND gate outputs a high-level signal and the second NAND gate outputs a low-level signal, the high-level signal is output to the controller.

[0089] S102, controlling the power on and off of the inverter according to the control signal.

[0090] In specific implementation, the above step S102 includes: if the control signal is a low-level signal, it indicates that the positive and negative terminals at the interface between the photovoltaic string and the inverter are not reversed, and the inverter is controlled to be powered on; if the control signal is a high-level signal, it indicates that the positive and negative terminals at the interface between the photovoltaic string and the inverter are reversed, and the inverter is controlled to be powered off.

[0091] The anti-reverse connection control method of this embodiment collects the positive voltage and negative voltage at the interface between the photovoltaic string and the inverter through a resistance sampling module and generates a sampling signal, and generates a control signal based on the sampling signal through a logic judgment module. According to the control signal, the on and off of the inverter is controlled, which can avoid the use of voltage sensors for voltage sampling and save costs. At the same time, after reverse connection, the power supply of the inverter can be cut off in time to improve safety.

[0092] Example 6

[0093] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the anti-reverse connection control method in the above embodiment is implemented.

[0094] The circuit embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0095] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A reverse connection protection circuit, applied to a photovoltaic power supply system, characterized in that: The circuit comprises a resistance sampling module, a logic judgment module and a controller connected in sequence; The resistance sampling module is connected to the interface between the photovoltaic string and the inverter, and is used to collect the positive voltage and the negative voltage at the interface, and generate a sampling signal based on the positive voltage and the negative voltage; the resistance sampling module includes: a first sampling unit, whose input end is connected to the positive terminal at the interface between the photovoltaic string and the inverter, and is used to collect the positive voltage and generate a first sampling signal; a second sampling unit, whose input end is connected to the negative terminal at the interface between the photovoltaic string and the inverter, and is used to collect the negative voltage and generate a second sampling signal; The logic judgment module is used to generate a control signal according to the sampling signal; the logic judgment module includes: a first NAND gate, whose first input end is connected to the output end of the first sampling unit, whose second input end is grounded, and whose output end is connected to a third NAND gate; when the first sampling signal is a high level signal, the first NAND gate outputs a high level signal, and when the first sampling signal is a low level signal, the first NAND gate, whose first input end is connected to the output end of the second sampling unit, whose second input end is connected to a first voltage source, and whose output end is connected to the third NAND gate; when the second sampling signal is a low level signal, the first NAND gate outputs a high level signal, and when the second sampling signal is a high level signal, the second NAND gate outputs a low level signal; the third NAND gate, whose first end is connected to the output end of the first NAND gate, whose second end is connected to the output end of the second NAND gate, and whose output end is connected to a controller; when the first NAND gate outputs a high level signal and the second NAND gate outputs a high level signal, the first NAND gate outputs a low level signal, and the second NAND gate outputs a high level signal, the first NAND gate outputs a high level signal and the second NAND gate outputs a low level signal, the second NAND gate outputs a high level signal to the controller; The controller is used to control the power on and off of the frequency converter according to the control signal.

2. The circuit according to claim 1, characterized in that The first sampling unit comprises: a first resistor, a first end of which is connected to the positive terminal, and a second end of which is connected to the logic judgment module; A second resistor has a first end connected between the positive terminal and the logic judgment module, and a second end connected to ground.

3. The circuit according to claim 1, characterized in that The second sampling unit comprises: a third resistor, a first end of which is connected to the negative terminal, and a second end of which is connected to the logic judgment module; A fourth resistor has a first end connected between the negative terminal and the logic judgment module, and a second end connected to the ground.

4. The circuit according to claim 1, characterized in that The circuit further comprises: The voltage conversion module is arranged between the logic judgment module and the controller, and is used to convert the high voltage signal into a low voltage signal based on the control signal output by the logic judgment module, and output it to the controller.

5. A photovoltaic power supply system, comprising a photovoltaic string and a frequency converter, characterized in that: The photovoltaic power supply system further comprises an anti-reverse connection circuit as claimed in any one of claims 1 to 4.

6. The photovoltaic power supply system according to claim 5, characterized in that: The photovoltaic power supply system also includes: A controllable switch component, which is a normally closed switch, used to close or open under the control of the controller, thereby controlling the on and off of the frequency converter; The controller is specifically used to: when a high-level signal is input to its input end, control the controllable switch component to be disconnected, thereby controlling the inverter to be powered off; when a low-level signal is input to its input end, control the controllable switch component to be closed, thereby controlling the inverter to be powered on.

7. The photovoltaic power supply system according to claim 6, characterized in that: The controllable switch assembly comprises: The first switch group is arranged between the positive terminal of the photovoltaic string and the positive terminal of the inverter, and is used to control the connection and disconnection between the positive terminal of the photovoltaic string and the positive terminal of the inverter. The second switch group is arranged between the negative terminal of the photovoltaic string and the negative terminal of the inverter, and is used to control the connection and disconnection between the negative terminal of the photovoltaic string and the negative terminal of the inverter.

8. A photovoltaic air conditioner, characterized in that: A photovoltaic power supply system comprising any one of claims 5 to 7.

9. A reverse connection prevention control method, applied to the reverse connection prevention circuit according to any one of claims 1 to 4, characterized in that: The method comprises: Acquire a control signal; wherein the control signal is generated based on a sampling signal at an interface between a photovoltaic string and a frequency converter, and the sampling signal is generated based on a positive voltage and a negative voltage at the interface; The inverter is controlled to be powered on and off according to the control signal.

10. The method according to claim 9, characterized in that Controlling the on and off of the frequency converter according to the control signal includes: If the control signal is a low level signal, the frequency converter is controlled to be powered on; If the control signal is a high level signal, the frequency converter is controlled to be powered off.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to claim 9 or 10 is implemented.

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