Photovoltaic panel anti-reverse connection device and photovoltaic inverter

Abstract

This utility model discloses a photovoltaic panel reverse connection protection device and a photovoltaic inverter. The photovoltaic panel reverse connection protection device includes multiple MPPT units, each MPPT unit having a PV input terminal for connecting to the photovoltaic panel and a DC / DC module disposed between the PV input terminal and the DC bus; wherein the first MPPT unit further includes a first diode, which is forward connected between the PV input terminal and the DC / DC module; the photovoltaic panel reverse connection protection device also includes a second diode and a third diode; the anode of the second diode is connected to the cathode of the PV input terminal of the first MPPT unit, and the cathode of the second diode is connected to the anode of the auxiliary switching power supply; the cathode of the third diode is connected to the anode of the PV input terminal of the first MPPT unit, and the anode of the third diode is connected to the cathode of the auxiliary switching power supply. This utility model can solve the problem of damage to the switching transistors and their parasitic diodes caused by reverse connection of multiple MPPT panels, and has the advantages of simple circuit, fewer components, low cost, and saving PCB space.

Description

Technical Field

[0001] This utility model relates to a photovoltaic panel anti-reverse connection device and a photovoltaic inverter. Background Technology

[0002] In the photovoltaic industry, the DC / DC circuit of a photovoltaic inverter's front-end needs to consider the damage to power devices caused by reversed polarity of the photovoltaic panel (hereinafter referred to as the photovoltaic panel). Currently, traditional DC / DC boost circuits use IGBTs as switching transistors, which can withstand the short-circuit current when the photovoltaic panel is reverse-connected through the IGBT's own body diode. With the development of semiconductor devices and technologies, the decrease in the cost of SiC (silicon carbide) and the increase in photovoltaic panel power, SiC MOS can be gradually used as the switching device in the DC / DC boost circuit of the photovoltaic inverter's front-end. However, the parasitic diode voltage drop of SiC MOS is relatively large, generally 4-5V, which cannot withstand the losses generated by the short circuit when the photovoltaic panel is reverse-connected. The SiC MOS will be damaged after being subjected to the short-circuit current of the photovoltaic panel for a long time. Traditional solutions (such as...) Figure 1 A silicon diode needs to be connected in parallel outside the SiC MOS to provide a circuit when the photovoltaic panel is reverse-connected. The short-circuit current flows through the parallel diode to protect the SiC MOS from damage. However, traditional solutions require a parallel diode for each MPPT with a large number of channels, resulting in more power devices, higher costs, and a larger PCBA (circuit board) space requirement, which are significant drawbacks.

[0003] The information disclosed in the background section is only intended to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Utility Model Content

[0004] This invention provides a photovoltaic panel reverse connection protection device and a photovoltaic inverter. By simply adding a first diode to the main circuit of one MPPT (Maximum Power Point Tracking) unit and a second and third diode between the PV positive and negative terminals and the auxiliary switching power supply (SMPS), the problem of damage to the switching transistors and their parasitic diodes caused by reverse connection of multiple MPPT panels can be solved. It has the advantages of simple circuit, fewer components, low cost, and saving PCB space.

[0005] The first aspect of this utility model provides a photovoltaic panel reverse connection protection device, which includes a multi-channel MPPT unit, each of the MPPT units having a PV input terminal for connecting to the photovoltaic panel and a DC / DC module disposed between the PV input terminal and the DC bus.

[0006] The multi-channel MPPT unit includes a first MPPT unit, and the first MPPT unit further includes a first diode, which is forward connected between the PV input terminal and the DC / DC module;

[0007] The photovoltaic panel reverse connection protection device further includes a second diode and a third diode; the positive terminal of the second diode is connected to the negative terminal of the PV input terminal of the first MPPT unit, and the negative terminal of the second diode is connected to the positive terminal of the auxiliary switching power supply; the negative terminal of the third diode is connected to the positive terminal of the PV input terminal of the first MPPT unit, and the positive terminal of the third diode is connected to the negative terminal of the auxiliary switching power supply.

[0008] In a preferred embodiment, only the first MPPT unit includes the first diode, and only the first MPPT unit, the second diode, and the third diode are connected.

[0009] In a preferred embodiment, the DC / DC module of each MPPT unit includes a switching transistor and a parasitic diode connected in reverse parallel to the switching transistor;

[0010] When the first MPPT unit is reverse-connected to the photovoltaic panel, the first diode will cut off the reverse voltage, so that the short-circuit current flowing through the switching transistor of the first MPPT unit is zero.

[0011] Further or optionally, when one of the MPPT units other than the first MPPT unit is reverse-connected to the photovoltaic panel, the switching transistor of the reverse-connected MPPT unit is in the on state, and the short-circuit current flows through the switching transistor.

[0012] In a more preferred embodiment, the DC / DC module of each MPPT unit further includes a boost inductor, a boost diode, and a switching transistor. The boost inductor is connected in series with the positive terminal of the PV input terminal, the boost diode is connected in series with the boost inductor, one end of the switching transistor is connected to the connection point of the boost inductor and the boost diode, and the other end of the switching transistor is connected to the negative terminal of the PV input terminal.

[0013] In a specific and preferred embodiment, the switching transistor includes a SiC MOS transistor.

[0014] In a preferred embodiment, the photovoltaic panel reverse connection protection device further includes a voltage sampling unit and a current sampling unit. The voltage sampling unit is connected between the positive and negative terminals of the PV input terminal of the first MPPT unit, and each MPPT unit includes the current sampling unit.

[0015] In a preferred embodiment, the anode of the first diode is connected to the anode of the PV input terminal of the first MPPT unit, and the cathode of the first diode is connected to the anode of the first MPPT unit.

[0016] In a preferred embodiment, when the first MPPT unit is positively connected, both the second diode and the third diode are in the off state.

[0017] In a preferred embodiment, when the first MPPT unit is connected in the positive direction and all other MPPT units are connected in the negative direction, the second diode and the third diode are configured to form a circuit between the photovoltaic panel connected to the first MPPT unit and the auxiliary switching power supply, and the photovoltaic panel supplies power to the auxiliary switching power supply.

[0018] In a preferred embodiment, the auxiliary switching power supply and the switching control module are electrically connected to supply power to it, and the switching control module is electrically connected to the control terminal of the switching transistor of each DC / DC module.

[0019] In a specific and preferred embodiment, the first diode is a power silicon diode, and the second and third diodes are signal diodes.

[0020] A second aspect of this utility model provides a photovoltaic inverter that includes the aforementioned photovoltaic panel reverse connection protection device.

[0021] The above-mentioned solution adopted in this utility model has the following advantages:

[0022] In this invention, when the panel of the first MPPT unit is reverse-connected, the first diode is used to cut off the reverse voltage, so that the switching transistor and its parasitic diode of this MPPT unit do not bear current; by simply adding a line to one MPPT unit, the reverse connection protection of multiple MPPT units can be achieved, solving the problem of damage to the switching transistor (such as SiC MOS switch) when the photovoltaic panel is reverse-connected; it has the advantages of simple circuit, fewer components, low cost, and saving PCB space.

[0023] In some preferred embodiments, the circuit design of this utility model allows the first MPPT unit to use the second and third diodes after reverse connection so that the reverse-connected photovoltaic panel can still provide voltage for the auxiliary switching power supply, and the normal operation of the circuit is not affected when the photovoltaic panel is connected in the correct direction. Attached Figure Description

[0024] To more clearly illustrate the technical solution of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a circuit diagram of a photovoltaic power generation system that uses a known photovoltaic panel reverse connection protection device.

[0026] Figure 2 This is a circuit diagram of a photovoltaic power generation system including a photovoltaic panel reverse connection protection device according to an embodiment of the present utility model.

[0027] Figure 3 This is a flowchart of a photovoltaic panel anti-reverse connection method according to an embodiment of the present utility model. Detailed Implementation

[0028] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art. It should be noted that the description of these embodiments is for the purpose of aiding understanding the present invention, but does not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] like Figure 1 As shown, the switching transistors in the front-end DC / DC BOOST circuit of the photovoltaic inverter are SiC MOSFETs (Q1, Q2, ..., Qn). Given the large voltage drop of the parasitic diodes (D21, D22, ..., D2n) of the SiC MOSFETs, typically 4-5V, they cannot withstand the losses generated by the short circuit when the photovoltaic panels (PV1, PV2, ..., PVn) are reverse-connected. The SiC MOSFETs would be damaged by prolonged exposure to the short-circuit current from the photovoltaic panels. Therefore, a silicon diode (D11, D12, ..., D1n) is connected in parallel with the SiC MOSFETs (Q1, Q2, ..., Qn) to provide a circuit when the photovoltaic panels are reverse-connected. The short-circuit current flows through the parallel diode (D11, D12, ..., D1n), thus protecting the SiC MOSFETs from damage. However, when there are many MPPT units, each MPPT unit requires a parallel diode for its SiC MOSFET, resulting in more power devices, higher costs, and a larger PCBA space footprint.

[0030] To address the issue of the parasitic diode in the SiC MOSFET being unable to withstand prolonged short-circuit current from the photovoltaic panel, some embodiments offer a design circuit that effectively solves this problem. For photovoltaic inverters with multiple MPPTs and single inputs, simply adding wiring to one MPPT resolves the issue of SiC MOSFET damage when the photovoltaic panel is reverse-connected. Some embodiments utilize the existing wiring within the photovoltaic inverter itself, requiring only a small number of additional lines. The circuitry is simple and straightforward, addressing the aforementioned problems in photovoltaic inverter use at a relatively low cost.

[0031] Figure 2 A photovoltaic power generation system with a photovoltaic panel reverse connection protection device 100 is shown as an application embodiment. (Refer to...) Figure 2 As shown, the photovoltaic panel reverse connection protection device 100 is a device arranged on the DC side of the photovoltaic inverter. It is connected to the photovoltaic panels PV1 to PVn to convert the DC power from the photovoltaic panels PV1 to PVn into DC / DC power and supply it to the inverter circuit of the photovoltaic inverter. The photovoltaic panel reverse connection protection device 100 includes multiple MPPT units 101, 102, 103, etc. The multiple MPPT units specifically include a first MPPT unit 101, a second MPPT unit 102, ..., an nth MPPT unit 103, which are respectively connected to one photovoltaic panel, such as PV1, PV2, ..., PVn.

[0032] Each MPPT unit has a PV input terminal for connecting photovoltaic panels PV1 to PVn and a DC / DC module 110 located between the PV input terminal and the DC bus (BUS+ and BUS-). The PV input terminal includes a positive PV+ terminal and a negative PV- terminal. The expected wiring configuration is as follows: the positive PV+ terminal is connected to the positive terminal of photovoltaic panels PV1 to PVn, and the negative PV- terminal is connected to the negative terminal of photovoltaic panels PV1 to PVn, i.e., the photovoltaic panels are connected in the correct orientation. However, in the event of a wiring fault resulting in reverse connection, the positive PV- terminal is connected to the positive terminal of photovoltaic panels PV1 to PVn, and the negative PV+ terminal is connected to the negative terminal of photovoltaic panels PV1 to PVn.

[0033] The first MPPT unit 101 in the multi-channel MPPT unit also includes a first diode D31, which is forward-connected between the PV input terminal of the first MPPT unit 101 and the DC / DC module 110. Specifically, the anode of the first diode D31 is connected to the anode PV1+ of the PV input terminal of the first MPPT unit 101, and the cathode of the first diode D31 is connected to the DC / DC module 110 of the first MPPT unit 101. The photovoltaic panel reverse connection protection device 100 also includes a second diode D32 and a third diode D33; the anode of the second diode D32 is connected to the cathode PV1- of the PV input terminal of the first MPPT unit 101, and the cathode of the second diode D32 is connected to the anode of the auxiliary switching power supply SMPS; the cathode of the third diode D33 is connected to the anode PV1+ of the PV input terminal of the first MPPT unit 101, and the anode of the third diode D33 is connected to the cathode of the auxiliary switching power supply SMPS. The first diode D31 can be a power silicon diode and used as a power transistor; the second diode D32 and the third diode D33 are small signal diodes and used as signal transistors.

[0034] It should be noted that only the first MPPT unit 101 includes the first diode D31, and only the first MPPT unit 101, the second diode D32, and the third diode D33 are connected. That is, only one MPPT unit needs to have its wiring added, while the other MPPT units can maintain their original wiring without adding or changing wiring to the other MPPT units.

[0035] When the first MPPT unit 101 is connected in the forward direction, both the second diode D32 and the third diode D33 are in the off state. When the first MPPT unit 101 is connected in the forward direction and all other MPPT units are connected in the reverse direction, the second diode D32 and the third diode D33 are configured to form a circuit between the photovoltaic panel connected to the first MPPT unit 101 and the auxiliary switching power supply SMPS, with the photovoltaic panel supplying power to the auxiliary switching power supply SMPS. The auxiliary switching power supply and the SMPS switching control module are electrically connected to supply power to it, and the switching control module is electrically connected to the control terminals of the switching transistors of each DC / DC module 110. The switching control module may include a DSP chip, which can be the main control chip DSP of the photovoltaic inverter. The switching control module can send square waves to the switching transistors of each DC / DC module 110, thereby driving each switching transistor to turn on or off accordingly.

[0036] Each MPPT unit's DC / DC module 110 includes switching transistors Q1, Q2 to Qn and parasitic diodes D21, D22 to D2n connected in reverse parallel to the switching transistors Q1, Q2 to Qn. Specifically, the switching transistors Q1, Q2 to Qn are SiC MOS transistors with parasitic diodes. When the first MPPT unit 101 is reverse-connected to the photovoltaic panel PV1, the first diode D31 cuts off the reverse voltage, making the short-circuit current flowing through the switching transistor Q1 of the first MPPT unit 101 zero. When any MPPT unit other than the first MPPT unit 101 is reverse-connected to the photovoltaic panel, the switching transistor of the reverse-connected MPPT unit is in the on state, and the short-circuit current flows through the switching transistor (specifically, the body of the SiC MOS transistor) and not through the parasitic diode of the SiC MOS transistor.

[0037] In one specific embodiment, the DC / DC module 110 of each MPPT unit further includes a boost inductor (L1, L2 to Ln) and a boost diode (D1, D2 to Dn). The boost inductor (L1, L2 to Ln) is connected in series with the positive terminal of the PV input, and the boost diode (D1, D2 to Dn) is connected in series with the boost inductor (L1, L2 to Ln). One end of the switching transistor (Q1, Q2 to Qn) is connected to the junction of the boost inductor (L1, L2 to Ln) and the boost diode (D1, D2 to Dn), and the other end of the switching transistor (Q1, Q2 to Qn) is connected to the negative terminal of the PV input. The DC / DC module 110 of each MPPT unit is identical.

[0038] Reference Figure 2 In each MPPT unit, the photovoltaic panel forms a BOOST boost circuit through inductor L, switching transistor Q, and boost diode D, converting the DC power from the photovoltaic panel into stable DC power for the BUS bus. The DC bus BUS+ is connected to the positive input terminal of the auxiliary switching power supply SMPS, and the DC bus BUS- is connected to the negative input terminal of the auxiliary switching power supply SMPS. The positive terminal of the bus electrolytic capacitor BUS_CAP is connected to the DC bus BUS+, and the negative terminal of BUS_CAP is connected to the DC bus BUS-.

[0039] The photovoltaic panel reverse connection protection device 100 also includes a voltage sampling unit 121 and a current sampling unit 122. The voltage sampling unit 121 is connected between the positive terminal PV1+ and the negative terminal PV1- of the PV input of the first MPPT unit 101, sampling the voltage of the photovoltaic panel PV1 connected to the first MPPT unit 101. Each MPPT unit 101, 102, and 103 includes a current sampling unit 122, which samples the current flowing through the main circuit of each MPPT unit. Specifically, the current sampling unit 122 is connected in series between the positive terminal of the PV input and the boost inductor to perform MPPT current detection.

[0040] For the multi-MPPT photovoltaic inverter in this embodiment, only one MPPT unit (i.e., the first MPPT unit 101) needs to have its circuitry increased. A silicon diode D31 is added to the main circuit of one MPPT unit. When the PV circuit is reverse-connected, the voltage generated by the photovoltaic panel is cut off, so that the BOOST switch Q1 of this circuit does not need to bear the short-circuit current. Therefore, the switch Q1 of this circuit will not be damaged due to the PV reverse connection. In this MPPT unit with the added silicon diode (first diode D31), a small diode (second diode D32 and third diode D33) is connected to the positive and negative terminals respectively to the input terminal (BUS terminal) of the auxiliary switching power supply SMPS. The diode (third diode D33) on the positive terminal is reverse-connected, and the diode (second diode D32) on the negative terminal is forward-connected. When PV1 in this path is not reverse-connected, both second diode D32 and third diode D33 are cut off and do not work. When PV1 in this path is reverse-connected, both second diode D32 and third diode D33 are turned on, and PV1 provides power to the auxiliary switching power supply SMPS, enabling the auxiliary switching power supply SMPS to work normally.

[0041] Once the auxiliary switching power supply SMPS is working normally, the inverter's main control chip DSP can also work normally. It can send a wave to open the gate of the switching transistor SiC of all MPPT units, turning on the switching transistor SiC of each MPPT BOOST line. This allows the short-circuit current of the photovoltaic panel to be borne by the SiC MOS, instead of flowing through the body diode of the SiC MOS. Since the on-resistance of the SiC MOS is small after it is turned on, the loss of the SiC MOS is small. Therefore, the SiC MOS will not be damaged due to the reverse connection of the photovoltaic panel.

[0042] The MPPT unit with added body diode (i.e., the first MPPT unit 101) can detect the MPPT voltage to determine if the photovoltaic panel is reverse-connected, and the DSP will issue an error message to remind the user to confirm the wiring. Other MPPT units can detect the reverse current of the MPPT to determine if the photovoltaic panel is reverse-connected, and the DSP will issue an error message to remind the user to confirm the wiring.

[0043] Reference Figure 3 As shown, the method for preventing reverse connection of a photovoltaic panel using the aforementioned photovoltaic panel reverse connection protection device includes the following steps:

[0044] Obtain the sampled value of the PV voltage of the first MPPT unit 101, and obtain the sampled value of the PV current of each MPPT unit;

[0045] If the PV voltage is negative, it is determined that there is a photovoltaic panel reverse connection fault in the first MPPT unit 101.

[0046] If the PV current of a certain MPPT unit is negative, it is determined that there is a photovoltaic panel reverse connection fault in the corresponding MPPT unit.

[0047] Among them, through Figure 2 The voltage sampling unit in the middle obtains the sampled value of the PV voltage of the first MPPT unit 101, and obtains the sampled value of the PV current of each MPPT unit through the current sampling unit of each MPPT unit.

[0048] If the PV current of a certain MPPT unit is negative, the switching transistor of the corresponding MPPT unit's DC / DC module 110 will be turned on, allowing the reverse short-circuit current to flow through the switching transistor.

[0049] Each MPPT unit's switching transistor turns on or off in response to a control signal from a switching control module, which is powered by an auxiliary switching power supply. If multiple MPPT units are reverse-connected, the second diode D32 and the third diode D33 will be reverse-connected to the photovoltaic panel of the first MPPT unit 101 and the auxiliary switching power supply to form a circuit, with the photovoltaic panel supplying power to the auxiliary switching power supply. If an MPPT unit and a photovoltaic panel are connected in the correct orientation, the photovoltaic panel connected in the correct orientation will supply power to the auxiliary switching power supply through the corresponding MPPT unit.

[0050] The working principle and logic of the SiC MOS protection in the above embodiment when the photovoltaic panel is reverse connected are as follows:

[0051] 1. When the photovoltaic panel PV1 is positively connected, the photovoltaic panel is connected to the DC / DC module 110 of the first MPPT unit 101 through the first diode D31. The BOOST circuit composed of L1, Q1 and D1 converts the PV voltage into a stable BUS voltage. At this time, the second diode D32 and the third diode D33 are both in the off state. Therefore, the addition of devices D31, D32 and D33 does not affect the operation of the normal circuit.

[0052] 2. When photovoltaic panel PV1 is connected in the forward direction, and any one of photovoltaic panels PV2 to PVn is connected in reverse while the other photovoltaic panels are connected in the forward direction, the auxiliary switching power supply SMPS works normally, and the inverter main control chip DSP works normally. The reverse current detection of MPPT can detect which panel is connected in reverse. The DSP sends a wave to keep the switching transistor of the MPPT unit of that line on, so that the SiC MOS of the line with the reverse photovoltaic panel is always conducting. The short-circuit current of the reverse photovoltaic panel passes through the SiC MOS body without passing through the parasitic diode. The loss of the SiC MOS is small after it is turned on, thus protecting the SiC MOS.

[0053] 3. When photovoltaic panel PV1 is reverse-connected, and photovoltaic panels PV2-PVn are positively connected while other photovoltaic panels are reverse-connected, if the voltage of the positively connected photovoltaic panels PV2-PVn is higher than that of PV1, the voltage of the positively connected photovoltaic panels PV2-PVn enters the input terminal of the auxiliary switching power supply SMPS through the boost circuit, enabling the auxiliary switching power supply SMPS to work normally. The inverter main control chip DSP works normally, and the reverse current detection of MPPT can detect which panel is reverse-connected. The DSP sends a wave to keep the switching transistor of the MPPT unit of that line on, so that the SiC MOS of the line with the reverse-connected photovoltaic panel is always conducting. The short-circuit current of the reverse-connected photovoltaic panel passes through the SiC MOS body without passing through the parasitic diode. The loss of the SiC MOS is small after it is turned on, thus protecting the SiCMOS. The reverse connection of the photovoltaic panel PV1 can be detected by voltage detection. Since the first diode D31 is cut off, the switching transistor Q1 of the first MPPT unit 101 does not bear the short-circuit current when the photovoltaic panel is reverse connected. The current flowing through the SiC MOS transistor of the first MPPT unit 101 is almost 0. Therefore, the SiC MOS will not be damaged due to the reverse connection of the photovoltaic panel PV1.

[0054] 4. When photovoltaic panel PV1 is reverse-connected, and photovoltaic panels PV2 through PVn are also all reverse-connected, the voltage of photovoltaic panel PV1 is cut off at the negative terminal of D31 through Q1. Therefore, there is a negative voltage between PV1+ and PV1- of the photovoltaic panel. The positive terminal of the photovoltaic panel connects to PV1- through diode D32 to the positive input terminal of the auxiliary switching power supply SMPS. The positive input terminal of the auxiliary switching power supply SMPS flows into the negative input terminal, and the negative input terminal of the auxiliary switching power supply SMPS flows back to PV+ through diode D33. PV+ connects to the negative terminal of the photovoltaic panel, thus forming a loop. Therefore, the reverse-connected photovoltaic panel PV1 supplies power to the auxiliary switching power supply SMPS, enabling the auxiliary switching power supply SMPS to operate normally. After the auxiliary switching power supply SMPS operates normally, the inverter main control chip DSP operates normally. Through MPPT reverse current detection, it can detect which panel is reverse-connected. The DSP sends a wave to keep the switching transistor of that panel on, so that the SiC MOS of that panel is always conducting. The short-circuit current of the reverse-connected photovoltaic panel passes through the SiC MOS body without passing through the parasitic diode. The loss is small after the SiC MOS is turned on, thus protecting the SiC MOS. The reverse connection of the photovoltaic panel PV1 can be detected by voltage detection. Since the first diode D31 is cut off, the switching transistor Q1 of the first MPPT unit 101 does not bear the short-circuit current when the photovoltaic panel is reverse connected. The current flowing through its SiC MOS transistor is almost 0. Therefore, the SiC MOS will not be damaged due to the reverse connection of the photovoltaic panel.

[0055] In the above embodiment, when the panel of the first MPPT unit 101 is reverse-connected, the first diode D31 is used to cut off the reverse voltage, so that the switching transistor and its parasitic diode of this MPPT unit do not carry current. Only one MPPT unit needs to be added to achieve reverse connection protection for multiple MPPT units, solving the problem of damage to the switching transistor (such as SICMOS switch) when the photovoltaic panel is reverse-connected. It has advantages such as simple circuitry, fewer components, low cost, and saving PCB space. The circuit design of the above embodiment allows the first MPPT unit 101 to still provide voltage to the auxiliary switching power supply even after reverse connection using the second diode D32 and the third diode D33, and the photovoltaic panel can still provide voltage when reverse-connected, without affecting the normal operation of the circuit when the photovoltaic panel is connected correctly.

[0056] As indicated in this specification and claims, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, and these steps and elements do not constitute an exclusive list; the method or apparatus may also include other steps or elements. The term "and / or" as used herein includes any combination of one or more of the associated listed items.

[0057] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or it can be indirectly fixed or connected to the other feature. Furthermore, the descriptions of "upper," "lower," "left," and "right" used in this utility model are only relative to the relative positional relationships of the various components of this utility model in the accompanying drawings.

[0058] The above embodiments are only for illustrating the technical concept and features of this utility model, and are preferred embodiments. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it accordingly, and should not be construed as limiting the protection scope of this utility model. All equivalent transformations or modifications made based on the principles of this utility model should be covered within the protection scope of this utility model.

Claims

1. A photovoltaic panel reverse connection protection device, comprising multiple MPPT units, each MPPT unit having a PV input terminal for connecting to the photovoltaic panel and a DC / DC module disposed between the PV input terminal and a DC bus; characterized in that The multi-channel MPPT unit includes a first MPPT unit, and the first MPPT unit further includes a first diode. The anode of the first diode is connected to the anode of the PV input terminal of the first MPPT unit, and the cathode of the first diode is connected to the DC / DC module of the first MPPT unit. The photovoltaic panel reverse connection protection device further includes a second diode and a third diode; the positive terminal of the second diode is connected to the negative terminal of the PV input terminal of the first MPPT unit, and the negative terminal of the second diode is connected to the positive terminal of the auxiliary switching power supply; the negative terminal of the third diode is connected to the positive terminal of the PV input terminal of the first MPPT unit, and the positive terminal of the third diode is connected to the negative terminal of the auxiliary switching power supply. When the first MPPT unit is positively connected, both the second diode and the third diode are in the off state; When the first MPPT unit is connected in the forward direction and all other MPPT units are connected in the reverse direction, the second diode and the third diode are configured to form a circuit between the photovoltaic panel connected to the first MPPT unit and the auxiliary switching power supply, and the photovoltaic panel supplies power to the auxiliary switching power supply.

2. Photovoltaic panel reverse connection prevention device according to claim 1, characterized in that, Only the first MPPT unit includes the first diode, and only the first MPPT unit, the second diode, and the third diode are connected.

3. The photovoltaic panel reverse connection prevention device of claim 1, wherein, The DC / DC module of each MPPT unit includes a switching transistor and a parasitic diode connected in reverse parallel to the switching transistor; When the first MPPT unit is reverse-connected to the photovoltaic panel, the first diode will cut off the reverse voltage, so that the short-circuit current flowing through the switching transistor of the first MPPT unit is zero. When one of the MPPT units other than the first MPPT unit is reverse-connected to the photovoltaic panel, the switching transistor of the reverse-connected MPPT unit is in the on state, and the short-circuit current flows through the switching transistor.

4. Photovoltaic panel reverse connection prevention device according to claim 3, characterized in that, Each MPPT unit's DC / DC module further includes a boost inductor and a boost diode. The boost inductor is connected in series with the positive terminal of the PV input terminal, and the boost diode is connected in series with the boost inductor. One end of the switching transistor is connected to the connection point of the boost inductor and the boost diode, and the other end of the switching transistor is connected to the negative terminal of the PV input terminal.

5. The photovoltaic panel reverse connection prevention device of claim 3, wherein, The switching transistor includes a SiC MOS transistor.

6. The photovoltaic panel reverse connection prevention device of claim 1, wherein, The photovoltaic panel reverse connection protection device further includes a voltage sampling unit and a current sampling unit. The voltage sampling unit is connected between the positive and negative terminals of the PV input terminal of the first MPPT unit, and each MPPT unit includes the current sampling unit.

7. The photovoltaic panel reverse connection prevention device of claim 1, wherein, The auxiliary switching power supply and the switching control module are electrically connected to provide power to it, and the switching control module is electrically connected to the control terminal of the switching transistor of each DC / DC module.

8. The photovoltaic panel reverse connection prevention device of claim 1, wherein, The first diode is a power silicon diode, and the second and third diodes are signal diodes.

9. A photovoltaic inverter, characterized in that, A photovoltaic panel anti-reverse connection device comprising a photovoltaic panel according to any one of claims 1 to 8.

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