Photovoltaic reverse connection alarm circuit and photovoltaic inverter

Abstract

This application provides a photovoltaic reverse connection alarm circuit and a photovoltaic inverter. The photovoltaic reverse connection alarm circuit includes: a first input terminal for connecting to the positive terminal of the photovoltaic panel; a second input terminal for connecting to the negative terminal of the photovoltaic panel; a step-down circuit for stepping down the input voltage; a unidirectional conducting element connected between the first input terminal and the step-down circuit or between the second input terminal and the step-down circuit, which does not conduct when the photovoltaic panel is correctly connected and conducts when the photovoltaic panel is reversed; and an alarm circuit that issues an alarm message when the positive and negative terminals of the photovoltaic panel are reversed. This application achieves a pre-warning function for photovoltaic reverse connection by setting up a step-down circuit and an alarm circuit. When the photovoltaic panel is reversed, the step-down circuit starts and supplies power to the alarm circuit, issuing an alarm message to prompt the user to correct the wiring error in time, avoiding damage to system components due to reverse connection, ensuring the normal operation of the photovoltaic system, and improving safety and reliability; it also has the advantages of low cost and low power consumption.

Description

Technical Field

[0001] This application relates to the fields of photovoltaic new energy and power electronics technology, and in particular to a photovoltaic reverse connection alarm circuit and a photovoltaic inverter. Background Technology

[0002] Photovoltaic inverters are the core equipment of photovoltaic new energy power generation systems. Reverse polarity of the photovoltaic DC input is a wiring fault that is very common during the on-site installation and operation and maintenance of photovoltaic inverters. When the positive and negative terminals of the photovoltaic input are reversed, the positive terminal of the photovoltaic panel will flow back to the negative terminal of the photovoltaic panel through the body diode of the power switching transistor inside the inverter. This causes the body diode to bear the entire short-circuit current of the photovoltaic panel, resulting in a large power loss. This not only prevents the inverter from starting and operating normally, but more seriously, the reverse voltage may break down the internal power devices (such as MOSFETs, IGBTs, etc.), rectifier diodes, and related control circuits, causing permanent damage to the equipment and seriously affecting the operational reliability and service life of the photovoltaic inverter.

[0003] To address this issue, existing technologies typically employ parallel high-current diodes to share the losses, or activate the heatsink fan for cooling when reverse current is detected. However, these methods are all passive protection measures after reverse connection occurs. Furthermore, the parallel high-current diode solution is costly and occupies heatsink space; the method of relying on other input sources to start the fan fails when no auxiliary input source is available, resulting in a protection blind zone. Summary of the Invention

[0004] This invention provides a photovoltaic reverse connection alarm circuit and a photovoltaic inverter, which solves the problems of existing photovoltaic reverse connection protection schemes, which are not only high in hardware cost, large in space, dependent on additional auxiliary input sources, and high in power consumption, but also can only provide passive protection after a reverse connection occurs, which still affects the use of the system.

[0005] To solve the above-mentioned technical problems, the present invention provides a photovoltaic reverse connection alarm circuit, comprising: a first input terminal for connecting to the positive terminal of a photovoltaic panel; a second input terminal for connecting to the negative terminal of a photovoltaic panel; a step-down circuit connected to the first and second input terminals for stepping down the input voltage; a unidirectional conducting element connected between the first input terminal and the step-down circuit or between the second input terminal and the step-down circuit, wherein the unidirectional conducting element is not conducting when the positive and negative terminals of the photovoltaic panel are correctly connected, and conducts when the positive and negative terminals of the photovoltaic panel are reversed; and an alarm circuit connected to the step-down circuit, wherein the alarm circuit issues an alarm message when the positive and negative terminals of the photovoltaic panel are reversed.

[0006] In some embodiments, the unidirectional conducting element is a diode, wherein: the diode is connected between the second input terminal and the step-down circuit, the anode of the diode is connected to the second input terminal, and the cathode of the diode is connected to the step-down circuit; or the diode is connected between the first input terminal and the step-down circuit, the anode of the diode is connected to the step-down circuit, and the cathode of the diode is connected to the first input terminal.

[0007] In some embodiments, the step-down circuit includes: a current-limiting resistor connected to a second input terminal; a voltage regulator unit, with a first terminal connected to the current-limiting resistor and a second terminal connected to the first input terminal and grounded; and a first capacitor connected in parallel between the first and second terminals of the voltage regulator unit.

[0008] In some embodiments, the voltage regulator unit is a Zener diode, with the cathode of the Zener diode connected to a current-limiting resistor and the anode of the Zener diode connected to the first input terminal and grounded.

[0009] In some embodiments, the step-down circuit includes: a first transistor, the collector of which is connected to a second input terminal; a bias resistor connected between the second input terminal and the base of the first transistor; a Zener diode, the cathode of which is connected to the base of the first transistor, and the anode of which is connected to the first input terminal and grounded; a voltage divider circuit including a fourth resistor and a fifth resistor connected in series, the fourth resistor being connected to the emitter of the first transistor, the fifth resistor being connected to the anode of the Zener diode, and the reference terminal of the Zener diode being connected between the fourth resistor and the fifth resistor; a second capacitor connected in series between the base of the first transistor and the fourth and fifth resistors; and a third capacitor, one end of which is connected to the emitter of the first transistor, and the other end of which is connected to the anode of the Zener diode.

[0010] In some embodiments, the alarm circuit includes a first light-emitting diode, which is connected to a step-down circuit and grounded.

[0011] In some embodiments, the alarm circuit further includes a first oscillation circuit, which includes: a second transistor, the emitter of which is connected to the step-down circuit via a first light-emitting diode, and the collector of which is grounded via an eighth resistor; a third transistor, the collector of which is connected to the base of which is connected to the second transistor via a seventh resistor, and the base of which is connected to the step-down circuit via a sixth resistor, and the emitter of which is grounded; and a fourth capacitor, one end of which is connected to the base of the third transistor, and the other end of which is connected between the collector of the second transistor and the eighth resistor.

[0012] In some embodiments, the alarm circuit includes a second light-emitting diode and a buzzer, wherein the second light-emitting diode is connected to the step-down circuit and grounded, and the buzzer is connected to the step-down circuit and grounded.

[0013] In some embodiments, the alarm circuit further includes a second oscillation circuit, which includes: a fourth transistor, the collector of which is connected to the step-down circuit via a second light-emitting diode and a ninth resistor, and the emitter of which is grounded; a fifth transistor, the collector of which is connected to the step-down circuit via a buzzer and a tenth resistor, and the emitter of which is grounded; a fifth capacitor, one end of which is connected to the base of the fourth transistor, and the other end of which is connected between the collector of the fifth transistor and the buzzer; a sixth capacitor, one end of which is connected to the base of the fifth transistor, and the other end of which is connected between the collector of the fourth transistor and the second light-emitting diode; an eleventh resistor, which is connected between the step-down circuit and the base of the fourth transistor; and a twelfth resistor, which is connected between the step-down circuit and the base of the fifth transistor.

[0014] The present invention also provides a photovoltaic inverter, comprising: a photovoltaic switch for connecting or disconnecting a photovoltaic panel; an inverter circuit connected to the photovoltaic switch; and a photovoltaic reverse connection alarm circuit as described above, wherein the photovoltaic reverse connection alarm circuit is connected between the photovoltaic switch and the photovoltaic panel.

[0015] The beneficial effects of this invention are: 1. Pre-warning: It can detect reverse connection faults and issue alarms before the photovoltaic switch is closed, allowing users to discover and correct wiring errors before closing the switch. This fundamentally avoids the power switch diodes from being subjected to short-circuit current surges after the switch is closed, eliminating the risk of device thermal failure and improving system safety and user experience. 2. Low power consumption design: An oscillation circuit is used to control the intermittent operation of the LED or buzzer, significantly reducing power consumption; 3. Low-cost implementation: The circuit is built using general-purpose low-cost components, eliminating the need for high-cost, high-current power components and requiring no additional heat sink area, thus reducing the hardware cost and overall size of the inverter; 4. High adaptability: Supports multiple photovoltaic inputs, making it easy to expand applications; 5. High reliability: It does not rely on other input sources, works independently, and ensures effective alarms under various operating conditions. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic block diagram of the first embodiment of a photovoltaic reverse connection alarm circuit according to this application; Figure 2This is a schematic block diagram of a second embodiment of a photovoltaic reverse connection alarm circuit according to this application; Figure 3 This is a circuit diagram of the first embodiment of the unidirectional conduction element in a photovoltaic reverse connection alarm circuit according to this application; Figure 4 This is a circuit diagram of a second embodiment of a unidirectional conduction element in a photovoltaic reverse connection alarm circuit according to this application; Figure 5 This is a circuit diagram of the first embodiment of the step-down circuit in a photovoltaic reverse connection alarm circuit of this application; Figure 6 This is a circuit diagram of the second embodiment of the step-down circuit in the photovoltaic reverse connection alarm circuit of this application; Figure 7 This is a circuit diagram of the first embodiment of the alarm circuit in the photovoltaic reverse connection alarm circuit of this application; Figure 8 This is a circuit diagram of the second embodiment of the alarm circuit in the photovoltaic reverse connection alarm circuit of this application; Figure 9 This is a schematic diagram of the composition of a photovoltaic inverter according to this application. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0019] In the description of this application, it should be understood that terms such as “first” and “second” are used only to distinguish similar objects and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0020] It should be noted that in the embodiments of this application, "connection" can be understood as electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.

[0021] like Figure 1 , Figure 2 As shown, the photovoltaic reverse connection alarm circuit of this application includes a first input terminal PV+, a second input terminal PV-, a step-down circuit 3, a unidirectional conducting element 2, and an alarm circuit 4.

[0022] The first input terminal PV+ is connected to the positive terminal (+) of the photovoltaic panel 1. The second input terminal PV- is connected to the negative terminal (-) of the photovoltaic panel 1. The step-down circuit 3 is connected to the first input terminal PV+ and the second input terminal PV- to step down the input voltage. A unidirectional conducting element 2 is connected between the first input terminal PV+ and the step-down circuit 3 (e.g., ...). Figure 1 (as shown); or, the unidirectional conducting element 2 is connected between the second input terminal PV- and the step-down circuit 3 (as shown). Figure 2 (As shown). When the positive (+) and negative (-) terminals of photovoltaic panel 1 are correctly connected, the unidirectional conduction element 2 is not conducting; when the positive (+) and negative (-) terminals of photovoltaic panel 1 are reversed, the unidirectional conduction element 2 conducts. The alarm circuit 4 is connected to the step-down circuit 3. When the positive (+) and negative (-) terminals of photovoltaic panel 1 are reversed, the alarm circuit 4 issues an alarm message.

[0023] When the positive terminal + and negative terminal - of photovoltaic panel 1 are correctly connected, that is, the first input terminal PV+ is connected to the positive terminal + of photovoltaic panel 1 and the second input terminal PV- is connected to the negative terminal - of photovoltaic panel 1, the unidirectional conduction element 2 is in the cut-off state, the step-down circuit 3 cannot obtain the working voltage, the alarm circuit 4 does not work, and no alarm information is issued.

[0024] When the positive terminal (+) and negative terminal (-) of photovoltaic panel 1 are reversed, i.e., the first input terminal PV+ is connected to the negative terminal (-) of photovoltaic panel 1 and the second input terminal PV- is connected to the positive terminal (+) of photovoltaic panel 1, the unidirectional conduction element 2 is turned on. The input voltage of photovoltaic panel 1 is applied to the step-down circuit 3 through the unidirectional conduction element 2. The step-down circuit 3 starts to work, and reduces the input voltage to provide a suitable working voltage for the alarm circuit 4. The alarm circuit 4 then issues an alarm message, thereby reminding the user that there is a reverse connection fault between the positive terminal (+) and negative terminal (-) of photovoltaic panel 1 before the system is officially put into operation.

[0025] This application, through the aforementioned design, achieves the function of proactively detecting reverse connection faults and issuing alarms before the photovoltaic switch is closed. This allows users to promptly detect and correct wiring errors before substantial damage occurs, fundamentally avoiding the risk of damage to power devices due to reverse current and voltage in traditional passive protection schemes, and significantly improving the safety of photovoltaic inverters during installation and maintenance. Simultaneously, this circuit does not rely on an external auxiliary power supply, operating solely on the output of the photovoltaic panel 1, ensuring stable and reliable reverse connection detection and alarm functions under various operating conditions, including when no other input source is available, further enhancing the system's applicability and reliability. Furthermore, this application uses conventional electronic components, avoiding high-cost, high-current diodes and additional cooling fans, simplifying the structure, reducing costs, minimizing size, and facilitating integration.

[0026] The following is combined with Figures 1 to 9 The present application will be further described in detail with reference to specific embodiments.

[0027] Combination Figures 1 to 4 As shown, the unidirectional conducting element 2 in this application is a diode D1.

[0028] Specifically, as the first embodiment of this application, reference is made to Figure 3 As shown, diode D1 is connected between the first input terminal PV+ and the step-down circuit 3; the anode of diode D1 is connected to the step-down circuit 3, and the cathode of diode D1 is connected to the first input terminal PV+.

[0029] When photovoltaic panel 1 is correctly connected, the first input terminal PV+ is connected to the positive terminal (+) of photovoltaic panel 1, and the second input terminal PV- is connected to the negative terminal (-) of photovoltaic panel 1. At this time, the cathode of diode D1 (connected to the first input terminal PV+) is connected to the positive terminal (+) of photovoltaic panel 1, and the anode (connected to the step-down circuit 3) is connected to the second input terminal PV- (i.e., the negative terminal (-) of photovoltaic panel 1) through the step-down circuit 3. Diode D1 is in a reverse-biased state and is cut off. Therefore, the step-down circuit 3 cannot obtain voltage from photovoltaic panel 1, and the alarm circuit 4 does not work due to lack of power and does not issue an alarm message. However, when photovoltaic panel 1 is reverse-biased, the first input terminal PV+ is connected to the negative terminal (-) of photovoltaic panel 1, and the second input terminal PV- is connected to the positive terminal (+) of photovoltaic panel 1. At this time, the anode of diode D1 is connected to the second input terminal PV- (i.e., the positive terminal (+) of photovoltaic panel 1) through the step-down circuit 3, and the cathode is connected to the first input terminal PV+ (i.e., the negative terminal (-) of photovoltaic panel 1). Diode D1 is in a forward-biased state and is turned on. The input voltage of photovoltaic panel 1 is applied to step-down circuit 3 through the conducting diode D1. Step-down circuit 3 works and provides working voltage for alarm circuit 4. Alarm circuit 4 then starts and issues an alarm message, thereby realizing the detection and alarm of reverse connection fault.

[0030] As a second embodiment of this application, reference is made to... Figure 4 As shown, diode D1 is connected between the second input terminal PV- and the step-down circuit 3; the anode of diode D1 is connected to the second input terminal PV-, and the cathode of diode D1 is connected to the step-down circuit 3.

[0031] When photovoltaic panel 1 is correctly connected, the first input terminal PV+ is connected to the positive terminal (+) of photovoltaic panel 1, and the second input terminal PV- is connected to the negative terminal (-) of photovoltaic panel 1. At this time, the anode of diode D1 is connected to the second input terminal PV- (i.e., the negative terminal (-) of photovoltaic panel 1), and the cathode is connected to the step-down circuit 3. The other end of the step-down circuit 3 is connected to the first input terminal PV+ (i.e., the positive terminal (+) of photovoltaic panel 1). Diode D1 is subjected to reverse voltage and is in the off state. Therefore, step-down circuit 3 cannot receive power, and alarm circuit 4 does not work. When photovoltaic panel 1 is reverse-connected, the first input terminal PV+ is connected to the negative terminal (-) of photovoltaic panel 1, and the second input terminal PV- is connected to the positive terminal (+) of photovoltaic panel 1. At this time, the anode of diode D1 is connected to the second input terminal PV- (i.e., the positive terminal (+) of photovoltaic panel 1), and the cathode is connected to the step-down circuit 3. The other end of the step-down circuit 3 is connected to the first input terminal PV+ (i.e., the negative terminal (-) of photovoltaic panel 1). Diode D1 is subjected to forward voltage and is turned on. The input voltage of photovoltaic panel 1 is applied to step-down circuit 3 through the conducting diode D1. After step-down processing, step-down circuit 3 provides a suitable operating voltage for alarm circuit 4, which then issues an alarm message to indicate that photovoltaic panel 1 is reverse connected.

[0032] The unidirectional conducting element 2 of this application adopts diode D1. Utilizing its unidirectional conductivity, it can accurately realize the circuit conduction function when the photovoltaic panel 1 is reverse connected and the cut-off function when it is forward connected. In addition, diode D1 has the characteristics of low cost, simple structure and high reliability.

[0033] Furthermore, such as Figure 4 As shown, the following description will take the second embodiment of this application as an example (i.e., diode D1 is connected between the second input terminal PV- and the step-down circuit 3).

[0034] As the first embodiment of the step-down circuit 3 of this application, refer to Figure 5 The step-down circuit 3 includes a current-limiting resistor, a voltage regulator unit, and a first capacitor C1.

[0035] The current-limiting resistor is connected to the second input terminal PV-. The first terminal of the voltage regulator is connected to the current-limiting resistor, and the second terminal is connected to the first input terminal PV+ and grounded. The first capacitor C1 is connected in parallel between the first and second terminals of the voltage regulator.

[0036] In this embodiment, the voltage regulator unit is a Zener diode ZD1; the current-limiting resistor includes a first resistor R1 and a second resistor R2 connected in series. Specifically, one end of the first resistor R1 is connected to the cathode of the diode ZD1, and the other end is connected to one end of the second resistor R2; the other end of the second resistor R2 is connected to the cathode of the Zener diode ZD1; the anode of the Zener diode ZD1 is connected to the first input terminal PV+ and grounded. One end of the first capacitor C1 is connected between the second resistor R2 and the cathode of the Zener diode ZD1, and the other end is connected to the anode (i.e., ground) of the Zener diode ZD1.

[0037] The working principle of the first embodiment of the step-down circuit 3 in this application is as follows: When photovoltaic panel 1 is reverse-connected, diode D1 conducts, and the voltage of photovoltaic panel 1 is applied to the first resistor R1 through the second input terminal PV- and diode D1. After being divided and current-limited by the first resistor R1 and the second resistor R2, it is applied to the cathode of Zener diode ZD1. After Zener diode ZD1 breaks down in reverse, the voltage across it stabilizes at the set regulated value, providing a stable operating voltage VCC for the subsequent alarm circuit 4. The first capacitor C1 acts as a filter, making the output operating voltage VCC more stable and ensuring that alarm circuit 4 can operate stably and reliably.

[0038] As a second embodiment of the step-down circuit 3 of this application, refer to Figure 6 The step-down circuit 3 includes a first transistor Q1, a bias resistor R3, a three-terminal Zener diode U1, a voltage divider circuit, a second capacitor C2, and a third capacitor C3.

[0039] In this embodiment, the voltage divider circuit includes a fourth resistor R4 and a fifth resistor R5 connected in series.

[0040] Specifically, the collector C of the first transistor Q1 is connected to the cathode of the diode D1. A bias resistor R3 is connected between the cathode of the diode D1 and the base B of the first transistor Q1. The base B of the first transistor Q1 is also connected to the cathode C of the three-terminal regulator U1. The emitter E of the first transistor Q1 is connected to a fourth resistor R4. A second capacitor C2 is connected in series between the base B of the first transistor Q1 and the fourth resistor R4 and the fifth resistor R5. The anode A of the three-terminal regulator U1 is connected to the first input terminal PV+ and grounded. The fifth resistor R5 is connected to the anode A of the three-terminal regulator U1. The reference terminal R of the three-terminal regulator U1 is connected between the fourth resistor R4 and the fifth resistor R5. One end of the third capacitor C3 is connected to the emitter E of the first transistor Q1, and the other end is connected to the anode A of the three-terminal regulator U1.

[0041] The working principle of the second embodiment of the step-down circuit 3 in this application is as follows: When photovoltaic panel 1 is reverse-connected, diode D1 conducts, and the input voltage of photovoltaic panel 1 is applied to the collector C of the first transistor Q1 through diode D1. A voltage divider circuit composed of the fourth resistor R4 and the fifth resistor R5 provides a bias voltage to the base B of the first transistor Q1, causing Q1 to conduct. The voltage output from its emitter E is then regulated by the three-terminal Zener diode U1 to output a stable operating voltage VCC. The second capacitor C2 and the third capacitor C3 filter the input and output voltages respectively, further improving voltage stability and ensuring the reliable operation of alarm circuit 4.

[0042] As the first embodiment of the alarm circuit 4 in this application, refer to Figure 7 (combined) Figure 5 , Figure 6 As shown in the figure, the alarm circuit 4 includes a first light-emitting diode LED1 and a first oscillation circuit.

[0043] In this embodiment, the first light-emitting diode LED1 is connected to the step-down circuit 3 and grounded. The first oscillation circuit includes a second transistor Q2, a third transistor Q3, and a fourth capacitor C4.

[0044] Specifically, the anode 1 of the first light-emitting diode LED1 and Figure 5 The first capacitor C1 of the step-down circuit 3 is connected, or is connected to... Figure 6 The third capacitor C3 of the step-down circuit 3 is connected; the cathode 2 of the first light-emitting diode LED1 is connected to the emitter E of the second transistor Q2. The collector C of the second transistor Q2 is grounded via the eighth resistor R8; the base B of the second transistor Q2 is connected to the collector C of the third transistor Q3 via the seventh resistor R7. The base B of the third transistor Q3 is connected to the collector C of the third transistor Q3 via the sixth resistor R6. Figure 5 The first capacitor C1 of the step-down circuit 3 is connected, or is connected to... Figure 6 The third capacitor C3 of the step-down circuit 3 is connected; the emitter E of the third transistor Q3 is grounded. One end of the fourth capacitor C4 is connected to the base B of the third transistor Q3, and the other end is connected between the collector C of the second transistor Q2 and the eighth resistor R8.

[0045] The working principle of the first embodiment of the alarm circuit 4 in this application is as follows: When the step-down circuit 3 outputs a stable operating voltage VCC, initially, VCC charges the fourth capacitor C4 through the sixth resistor R6. As charging progresses, the voltage across capacitor C4 gradually increases, meaning the potential at the base (B) of transistor Q3 gradually rises. Transistor Q3 then turns on because its base (B) reaches the turn-on voltage. This turn-on of Q3 also turns on transistor Q2. At this point, VCC powers the first LED1, which then lights up, indicating a reverse polarity fault in the photovoltaic panel 1 and prompting timely adjustment. Simultaneously, capacitor C4 begins to discharge, and the voltage across it gradually decreases. The potential at the base (B) of transistor Q3 also decreases. When the voltage drops to a certain value, transistor Q3 turns off, causing transistor Q2 to stop conducting. VCC then stops supplying power to LED1, and LED1 stops lighting up. VCC then recharges capacitor C4, repeating the process. This cycle repeats continuously, with the second transistor Q2 constantly turning on and off, causing the state of the first light-emitting diode LED1 to alternate between emitting light and not emitting light.

[0046] The alarm circuit 4 controls the lights to work intermittently through oscillation, thereby reducing power consumption. It can operate with low power consumption by relying solely on the power supply of the photovoltaic panel 1, and its power consumption is reduced by about half compared to constant voltage power supply.

[0047] As a second embodiment of the alarm circuit 4 in this application, refer to Figure 8 (combined) Figure 5 , Figure 6 As shown in the figure, the alarm circuit 4 includes a second light-emitting diode LED2, a buzzer BZ1, and a second oscillation circuit.

[0048] In this embodiment, the second light-emitting diode LED2 is connected to the step-down circuit 3 and grounded, and the buzzer BZ1 is connected to the step-down circuit 3 and grounded. The second oscillation circuit includes a fourth transistor Q4, a fifth transistor Q5, a fifth capacitor C5, a sixth capacitor C6, an eleventh resistor R11, and a twelfth resistor R12.

[0049] Specifically, the collector C of the fourth transistor Q4 is connected to the second light-emitting diode LED2, the ninth resistor R9, and... Figure 5 The first capacitor C1 of the step-down circuit 3 is connected, or is connected to... Figure 6 The third capacitor C3 in the step-down circuit 3 is connected; the emitter E of the fourth transistor Q4 is grounded; the eleventh resistor R11 is connected between the first capacitor C1 and the base B of the fourth transistor Q4, or between the third capacitor C3 and the base B of the fourth transistor Q4. The collector C of the fifth transistor Q5 is connected via the buzzer BZ1 and the tenth resistor R10 to... Figure 5The first capacitor C1 of the step-down circuit 3 is connected, or is connected to... Figure 6 The third capacitor C3 in the step-down circuit 3 is connected; the emitter E of the fifth transistor Q5 is grounded; the twelfth resistor R12 is connected between the first capacitor C1 and the base B of the fifth transistor Q5, or between the third capacitor C3 and the base B of the fifth transistor Q5. One end of the fifth capacitor C5 is connected to the base B of the fourth transistor Q4, and the other end is connected between the collector C of the fifth transistor Q5 and the buzzer BZ1; one end of the sixth capacitor C6 is connected to the base B of the fifth transistor Q5, and the other end is connected between the collector C of the fourth transistor Q4 and the second light-emitting diode LED2.

[0050] The working principle of the second embodiment of the alarm circuit 4 in this application is as follows: When the step-down circuit 3 outputs a stable operating voltage VCC, the fourth transistor Q4 and the fifth transistor Q5 are turned on simultaneously. This is because the parameters of the eleventh resistor R11, the twelfth resistor R12, the sixth capacitor C6, and the fifth capacitor C5 are different. If the fourth transistor Q4 is saturated and conducts first, the second LED2 lights up, one end of the sixth capacitor C6 is grounded, and the other end becomes negative, the fifth transistor Q5 will be cut off, and the buzzer BZ1 will not sound. Then, the working voltage VCC charges the sixth capacitor C6 through the twelfth resistor R12 and the fourth transistor Q4 until the base voltage B of the fifth transistor Q5 reaches the conduction voltage. Then, the fifth transistor Q5 conducts, the buzzer BZ1 sounds, one end of the fifth capacitor C5 is grounded, and the other end is negative, causing the fourth transistor Q4 to be cut off, and the second LED2 does not light up. Subsequently, the working voltage VCC charges the fifth capacitor C5 through the eleventh resistor R11 and the fifth transistor Q5 until the base voltage B of the fourth transistor Q4 reaches the conduction voltage, and then conducts. The above process is repeated. This cycle repeats continuously, with the fourth transistor Q4 and the fifth transistor Q5 alternately turning on and off, causing the second light-emitting diode LED2 and the buzzer BZ1 to work alternately, providing alternating flashing lights and audible alarms, enabling users to promptly detect and address the reverse connection fault of photovoltaic panel 1.

[0051] In a second embodiment of the alarm circuit 4 of this application, the power supply duration of the buzzer BZ1 can be changed by adjusting the values ​​of the eleventh resistor R11 and the fifth capacitor C5; and the power supply duration of the second light-emitting diode LED2 can be changed by adjusting the values ​​of the twelfth resistor R12 and the sixth capacitor C6.

[0052] The second embodiment of the alarm circuit 4 in this application reduces system power consumption by using a second oscillation circuit to control the second light-emitting diode LED2 or the buzzer BZ1 to work intermittently, and can operate with low power consumption by relying solely on the power supply of the photovoltaic panel 1.

[0053] In summary, the beneficial effects of this application are: The photovoltaic reverse connection alarm circuit provided in this application utilizes the characteristics of the unidirectional conducting element 2 (diode D1) to accurately and reliably detect the reverse connection status of the positive and negative terminals of the photovoltaic panel 1. When the photovoltaic panel 1 is correctly connected, diode D1 is cut off, the step-down circuit 3 does not work, and the alarm circuit 4 does not activate. However, when the photovoltaic panel 1 is reverse connected, diode D1 conducts, and the step-down circuit 3 converts the input voltage of the photovoltaic panel 1 into a stable operating voltage to supply the alarm circuit 4. The alarm circuit 4 then issues a clear and intuitive alarm signal through flashing LEDs and / or audible buzzer BZ1. The circuit structure is simple, and the core components such as diodes, transistors, resistors, capacitors, and Zener diodes are all conventional electronic components, which are inexpensive and readily available. Furthermore, by designing an oscillation circuit to control the intermittent operation of the alarm element, the overall power consumption is significantly reduced, allowing the circuit to operate with low power consumption solely powered by the photovoltaic panel 1 itself, without the need for an external power supply. In addition, the pre-warning method effectively ensures the safety of the photovoltaic system during installation and maintenance, avoiding equipment damage and safety hazards that may be caused by reverse connection of the photovoltaic panel 1.

[0054] Based on the same inventive concept, this application also provides a photovoltaic inverter, such as... Figure 9 As shown, the photovoltaic inverter includes: Photovoltaic switch 5 is used to connect or disconnect photovoltaic panel 1.

[0055] Inverter circuit 6 is connected to photovoltaic switch 5.

[0056] As mentioned above, the photovoltaic reverse connection alarm circuit 7 is connected between the photovoltaic switch 5 and the photovoltaic panel 1.

[0057] In this application, the other technical features of the photovoltaic inverter are the same as those disclosed in the aforementioned embodiment of the photovoltaic reverse connection alarm circuit 7, and will not be repeated here.

[0058] Therefore, this application discloses a photovoltaic reverse connection alarm circuit and a photovoltaic inverter. The photovoltaic reverse connection alarm circuit includes: a first input terminal for connecting to the positive terminal of the photovoltaic panel; a second input terminal for connecting to the negative terminal of the photovoltaic panel; a step-down circuit connected to the first and second input terminals for stepping down the input voltage; a unidirectional conducting element connected between the first input terminal and the step-down circuit or between the second input terminal and the step-down circuit, wherein the unidirectional conducting element is not conducting when the positive and negative terminals of the photovoltaic panel are correctly connected, and conducts when the positive and negative terminals of the photovoltaic panel are reversed; and an alarm circuit connected to the step-down circuit, which issues an alarm message when the positive and negative terminals of the photovoltaic panel are reversed. This application utilizes the characteristics of a unidirectional conducting element (diode) to accurately and reliably detect the reverse connection state of the positive and negative terminals of the photovoltaic panel. When the photovoltaic panel is correctly connected, the diode is cut off, the step-down circuit does not work, and the alarm circuit does not activate. However, when the photovoltaic panel is reverse-connected, the diode conducts, and the step-down circuit converts the input voltage of the photovoltaic panel into a stable operating voltage to supply the alarm circuit. The alarm circuit then issues a clear and intuitive alarm signal through flashing LEDs and / or audible buzzers. This circuit has a simple structure, and its core components, such as diodes, transistors, resistors, capacitors, and Zener diodes, are all conventional electronic components that are inexpensive and readily available. Furthermore, by designing an oscillation circuit to control the intermittent operation of the alarm components, the overall power consumption is significantly reduced, allowing the circuit to operate with low power solely powered by the photovoltaic panel itself, eliminating the need for an external power supply. In addition, this pre-warning mechanism effectively ensures the safety of the photovoltaic system during installation and maintenance, preventing equipment damage and safety hazards that may be caused by reverse connection of the photovoltaic panel.

[0059] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A photovoltaic reverse connection alarm circuit, characterized in that, include: The first input terminal is used to connect to the positive electrode of the photovoltaic panel; The second input terminal is used to connect to the negative electrode of the photovoltaic panel; A step-down circuit, connected to the first input terminal and the second input terminal, is used to step down the input voltage; A one-way conducting element is connected between the first input terminal and the step-down circuit or between the second input terminal and the step-down circuit. When the positive and negative terminals of the photovoltaic panel are correctly connected, the one-way conducting element is not conducting; when the positive and negative terminals of the photovoltaic panel are reversed, the one-way conducting element is conducting. An alarm circuit, connected to the step-down circuit, issues an alarm message when the positive and negative terminals of the photovoltaic panel are reversed.

2. The photovoltaic reverse connection alarm circuit according to claim 1, characterized in that, The unidirectional conducting element is a diode, wherein: The diode is connected between the second input terminal and the step-down circuit, with the anode of the diode connected to the second input terminal and the cathode of the diode connected to the step-down circuit; or The diode is connected between the first input terminal and the step-down circuit, with the anode of the diode connected to the step-down circuit and the cathode of the diode connected to the first input terminal.

3. The photovoltaic reverse connection alarm circuit according to claim 1, characterized in that, The step-down circuit includes: A current-limiting resistor is connected to the second input terminal; The voltage regulator unit has a first terminal connected to the current-limiting resistor and a second terminal connected to the first input terminal and grounded. The first capacitor is connected in parallel between the first and second terminals of the voltage regulator unit.

4. The photovoltaic reverse connection alarm circuit according to claim 3, characterized in that, The voltage regulator unit is a Zener diode. The cathode of the Zener diode is connected to the current-limiting resistor, and the anode of the Zener diode is connected to the first input terminal and grounded.

5. The photovoltaic reverse connection alarm circuit according to claim 1, characterized in that, The step-down circuit includes: The first transistor, wherein the collector of the first transistor is connected to the second input terminal; A bias resistor is connected between the second input terminal and the base of the first transistor; A three-terminal Zener diode, wherein the cathode of the three-terminal Zener diode is connected to the base of the first transistor, and the anode of the three-terminal Zener diode is connected to the first input terminal and grounded; The voltage divider circuit includes a fourth resistor and a fifth resistor connected in series. The fourth resistor is connected to the emitter of the first transistor, the fifth resistor is connected to the anode of the three-terminal Zener diode, and the reference terminal of the three-terminal Zener diode is connected between the fourth resistor and the fifth resistor. The second capacitor is connected in series between the base of the first transistor and the fourth and fifth resistors; The third capacitor has one end connected to the emitter of the first transistor and the other end connected to the anode of the three-terminal Zener diode.

6. The photovoltaic reverse connection alarm circuit according to any one of claims 1 to 5, characterized in that, The alarm circuit includes a first light-emitting diode, which is connected to the step-down circuit and grounded.

7. The photovoltaic reverse connection alarm circuit according to claim 6, characterized in that, The alarm circuit further includes a first oscillation circuit, the first oscillation circuit comprising: The emitter of the second transistor is connected to the step-down circuit via the first light-emitting diode, and the collector of the second transistor is grounded via the eighth resistor. The collector of the third transistor is connected to the base of the second transistor via a seventh resistor, the base of the third transistor is connected to the step-down circuit via a sixth resistor, and the emitter of the third transistor is grounded. The fourth capacitor has one end connected to the base of the third transistor and the other end connected between the collector of the second transistor and the eighth resistor.

8. The photovoltaic reverse connection alarm circuit according to any one of claims 1 to 5, characterized in that, The alarm circuit includes a second light-emitting diode and a buzzer. The second light-emitting diode is connected to the step-down circuit and grounded, and the buzzer is connected to the step-down circuit and grounded.

9. The photovoltaic reverse connection alarm circuit according to claim 8, characterized in that, The alarm circuit further includes a second oscillation circuit, the second oscillation circuit comprising: The fourth transistor has its collector connected to the step-down circuit via the second light-emitting diode and the ninth resistor, and its emitter is grounded. The fifth transistor has its collector connected to the step-down circuit via the buzzer and the tenth resistor, and its emitter is grounded. The fifth capacitor has one end connected to the base of the fourth transistor and the other end connected between the collector of the fifth transistor and the buzzer. The sixth capacitor has one end connected to the base of the fifth transistor and the other end connected between the collector of the fourth transistor and the second light-emitting diode. The eleventh resistor is connected between the step-down circuit and the base of the fourth transistor; The twelfth resistor is connected between the step-down circuit and the base of the fifth transistor.

10. A photovoltaic inverter, characterized in that, include: Photovoltaic switches are used to connect or disconnect photovoltaic panels; The inverter circuit is connected to the photovoltaic switch; The photovoltaic reverse connection alarm circuit as described in any one of claims 1 to 9, wherein the photovoltaic reverse connection alarm circuit is connected between the photovoltaic switch and the photovoltaic panel.

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