Multiple-input photovoltaic device, system and standby voltage control method thereof

Abstract

The application discloses a kind of multiple input photovoltaic equipment, system and standby voltage control method thereof, comprising: first power module and at least one second power module connected in series, the first power module and second power module are used to control the output power of photovoltaic DC power connected with its input end;Main control module is connected with first power module and second power module, for controlling the working state of first power module and second power module;Voltage control module, the output end of the voltage control module is connected in parallel with first power module, for controlling the standby voltage of the photovoltaic equipment, and the standby voltage of the photovoltaic equipment is maintained at set value.The standby voltage of photovoltaic equipment in standby state is maintained at set value, it is convenient to verify the number of photovoltaic equipment in each photovoltaic string by measuring the standby voltage of photovoltaic string when installing, and the scheme of the application simplifies the control of photovoltaic equipment standby voltage, and reduces product cost.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, and in particular to a multi-input photovoltaic device, system and its standby voltage control method. Background Technology

[0002] Due to the renewable and clean nature of solar energy, photovoltaic (PV) power generation technology has developed rapidly. Existing PV power generation systems generally include multiple PV strings and PV inverters. Each PV string includes multiple PV devices connected in series and a PV DC power supply connected to the PV devices, such as a switch or optimizer.

[0003] The number of photovoltaic (PV) devices in a PV string is determined during the PV system design. After the PV strings are installed, to verify the correct installation of all PV devices in each string, the string voltage is typically measured to check the number and connection of the PV devices. To obtain accurate measurement results, the standby voltage of each PV device must be ensured to be a set value during testing. In existing technologies, to reduce costs and simplify installation, PV devices generally have multiple power modules connected in series. Each power module is connected to a PV DC power supply to control the power output of the connected PV DC power supply. To simplify control and reduce interference, the ground of the PV device is generally placed between the series outputs of any two power modules. However, this results in a complex and costly standby voltage control circuit for such PV devices. Therefore, it is essential to propose a simple and low-cost technical solution for standby voltage control of multi-input PV devices. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a multi-input photovoltaic device, system and a method for controlling the output voltage to a set value in standby mode.

[0005] In a first aspect, to achieve the aforementioned objectives, this application proposes a multi-input photovoltaic device, characterized in that it comprises:

[0006] A first power module and at least one second power module are connected in series, wherein the first power module and the second power module are respectively used to control the output power of the photovoltaic DC power supply connected to their input terminals;

[0007] A voltage control module is connected in parallel with the output terminal of the first power module to control the standby voltage of the photovoltaic device and maintain the standby voltage of the photovoltaic device at a set value.

[0008] Furthermore, it also includes: a main control module, connected to the first power module and the second power module, used to control the working state of the first power module and the second power module. When the photovoltaic equipment is in standby mode, the main control module controls the output of the second power module to be short-circuited.

[0009] Furthermore, the main control module is also connected to the voltage control module, and when the photovoltaic device is in standby mode, it provides an enable signal to the voltage control module to enable the voltage control module.

[0010] Furthermore, the output terminal of the first power module includes a high-potential terminal and a low-potential terminal, with the low-potential terminal connected to a reference ground.

[0011] Furthermore, the voltage control module includes an anti-reverse diode and a voltage regulator unit connected in series. The voltage regulator unit is used to provide a preset voltage, and the output terminal of the voltage regulator unit is connected to the output terminal of the first power module through the anti-reverse diode.

[0012] Furthermore, the first power module and the second power module include a switching transistor for controlling the connection or disconnection of the corresponding photovoltaic DC power supply with the power bus and a freewheeling transistor for providing a freewheeling channel. When the photovoltaic device is in standby mode, the main control module controls the switching transistor and freewheeling transistor of the first power module to disconnect, and the switching transistor of the second power module to disconnect and the freewheeling transistor to conduct, so that the output of the corresponding second power module is short-circuited.

[0013] Furthermore, it also includes an auxiliary power supply module, which is used to draw power from the photovoltaic DC power supply connected to the input terminal of the first power module and / or the second power module to supply power to the main control module and the voltage control module.

[0014] Furthermore, it also includes a current-sensing resistor connected in series between the first power module and the second power module, one end of which is connected to a reference ground for detecting the power bus current.

[0015] Secondly, to achieve the aforementioned objectives, this application also proposes a method for controlling the standby voltage of a multi-input photovoltaic device, used to control the standby voltage of the multi-input photovoltaic device as described in any of the preceding claims, comprising:

[0016] A voltage control module is connected in parallel with the output of the first power module. This voltage control module controls the standby voltage of the photovoltaic device and maintains the standby voltage of the photovoltaic device at a set value.

[0017] The first power module is connected in series with at least one second power module, and is used to control the output power of the photovoltaic DC power supply connected to its input terminal.

[0018] Thirdly, to achieve the aforementioned objectives, this application also proposes a photovoltaic system, comprising:

[0019] At least one photovoltaic string, the photovoltaic string comprising a plurality of photovoltaic devices connected in series and a photovoltaic DC power supply connected to the photovoltaic devices, wherein the photovoltaic devices are configured as multi-input photovoltaic devices as described in any of the preceding claims.

[0020] Compared with the prior art, the beneficial effects of the present invention are: by controlling the output voltage of the photovoltaic equipment in the standby state through the main control module and the voltage control module, the output voltage of the photovoltaic equipment is kept stable at the set value, which makes it convenient to verify the number and connection relationship of photovoltaic equipment in each photovoltaic string by measuring the string voltage of the photovoltaic string during installation. In addition, the solution of this application simplifies the control of the standby voltage of the photovoltaic equipment and reduces the product cost. Attached Figure Description

[0021] Figure 1 This is a structural schematic diagram of one implementation of an embodiment of the present invention;

[0022] Figure 2 This is a structural schematic diagram of another implementation of an embodiment of the present invention;

[0023] Figure 3 This is a circuit connection diagram of one implementation of an embodiment of the present invention;

[0024] Figure 4 This is a circuit connection diagram of one implementation of an embodiment of the present invention;

[0025] Figure 5 This is a circuit connection diagram of one implementation of an embodiment of the present invention;

[0026] Figure 6 This is a circuit connection diagram of one implementation of an embodiment of the present invention;

[0027] Figure 7 This is a structural schematic diagram of another implementation of an embodiment of the present invention.

[0028] In the attached diagram, 101: First photovoltaic DC power supply; 102: Second photovoltaic DC power supply; 103: Third photovoltaic DC power supply; 200: Main control module; 300: Voltage control module; 401: First power module; 402: Second power module; 402′: Second power module; 500: Auxiliary power supply module. Detailed Implementation

[0029] The present invention is described below based on embodiments, but the invention is not limited to these embodiments. In the detailed description of the invention below, certain specific details are described in detail. Those skilled in the art will fully understand the invention even without these details. To avoid obscuring the essence of the invention, well-known methods, processes, flows, elements, and circuits are not described in detail.

[0030] Furthermore, those skilled in the art should understand that the accompanying drawings provided herein are for illustrative purposes only and are not necessarily drawn to scale.

[0031] Furthermore, it should be understood that in the following description, "circuit" refers to a conductive loop consisting of at least one element or sub-circuit connected by electrical or electromagnetic connections. When an element or circuit is said to be "connected" to another element or "connected" between two nodes, it can be directly coupled or connected to another element, or there may be intermediate elements. The connection between elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected" to another element, it means that there are no intermediate elements between them.

[0032] Unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as encompassing rather than being exclusive or exhaustive; that is, meaning "including but not limited to."

[0033] In the description of this invention, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0034] This application provides a multi-input photovoltaic device, including:

[0035] A first power module and at least one second power module are connected in series, wherein the first power module and the second power module are respectively used to control the output power of the photovoltaic DC power supply connected to their input terminals;

[0036] A voltage control module is connected in parallel with the output terminal of the first power module to control the standby voltage of the photovoltaic device and maintain the standby voltage of the photovoltaic device at a set value.

[0037] Furthermore, it also includes: a main control module, connected to the first power module and the second power module, used to control the working state of the first power module and the second power module; when the photovoltaic equipment is in standby mode, the main control module controls the output of the second power module to be short-circuited.

[0038] Furthermore, the main control module is also connected to the voltage control module, and when the photovoltaic device is in standby mode, it provides an enable signal to the voltage control module to enable the voltage control module.

[0039] Furthermore, the multi-input photovoltaic device also includes an auxiliary power supply module, which draws power from the photovoltaic DC power supply connected to the input terminals of the first power module and / or the second power module to supply power to the main control module and the voltage control module.

[0040] A photovoltaic DC power supply can be a single photovoltaic module, multiple photovoltaic modules connected in series / parallel, or multiple photovoltaic cell sub-strings connected in series / parallel.

[0041] The standby voltage of the photovoltaic device is the output voltage of the photovoltaic device when it is in standby mode.

[0042] As one implementation method, such as Figure 1 As shown, taking two interconnected first power modules 401 and second power modules 402 as an example, the first power module 401 is connected to a first photovoltaic DC power supply 101 at its input terminal, and the second power module 402 is connected to a second photovoltaic DC power supply 102 at its input terminal. The first power module 401 controls the output power of the first photovoltaic DC power supply 101, and the second power module 402 controls the output power of the second photovoltaic DC power supply 102. The first power module 401 and the second power module 402 are connected in series and then connected in parallel to the output terminal of the multi-input photovoltaic device. The output terminal of the multi-input photovoltaic device provides the output voltage Vout of the multi-input photovoltaic device, which is the sum of the output voltages of the first power module 401 and the second power module 402. The series connection point of the first power module 401 and the second power module 402 is the reference ground.

[0043] The voltage control module 300 is connected in parallel with the output terminal of the first power module 401 to control the standby voltage of the photovoltaic device to a set value when it is in standby mode.

[0044] The main control module 200 is electrically connected to the first power module 401 and the second power module 402, and simultaneously controls the working state of the first power module 401 and the second power module 402. When the photovoltaic device is in standby mode, the main control module 200 controls the first power module 401 and the second power module 402 to disconnect the first photovoltaic DC power supply 101, the second photovoltaic DC power supply 102 and the power bus respectively. The power bus is, for example, a series connection line between photovoltaic devices. At the same time, the main control module 200 controls the output of the second power module 402 to be short-circuited, so that the output voltage of the first power module 401 is equal to the output voltage Vout of the photovoltaic device. Thus, the voltage control module 300 can maintain the standby voltage of the photovoltaic device at the set value.

[0045] The auxiliary power supply module 500 is used to supply power to the main control module 200 and the voltage control module 300. The auxiliary power supply module 500 draws power from any photovoltaic DC power source or from a portion of the photovoltaic DC power sources connected to the multi-input photovoltaic device. In this implementation, the auxiliary power supply module 500 draws power from the first photovoltaic DC power source 101.

[0046] The above settings ensure that the standby voltage of the photovoltaic equipment remains stable at the set value during standby mode. This facilitates verification of the number and connection relationship of photovoltaic devices in each photovoltaic string by measuring the string voltage of the photovoltaic string during installation. Furthermore, the solution in this application simplifies the control of the standby voltage of the photovoltaic equipment and reduces product costs.

[0047] As one implementation method, such as Figure 2 As shown, the main control module 200 outputs an enable signal EN to the voltage control module 300. The enable signal EN controls the working state of the voltage control module 300. When the photovoltaic equipment is in standby mode, the main control module 200 enables the voltage control module 300 through the enable signal EN, so that the voltage control module 300 works. When the photovoltaic equipment is working normally, the main control module 200 controls the voltage control module 300 to stop working through the enable signal EN, so as to reduce the loss of the voltage control module 300.

[0048] As one implementation method, photovoltaic devices are switch-off devices, such as... Figure 3 As shown, the first power module 401 includes a switching transistor S11 for controlling the connection between the first photovoltaic DC power supply 101 and the power bus, and a freewheeling transistor D11 connected in parallel with the output terminal of the first power module 401. The second power module 402 includes a switching transistor S21 for controlling the connection between the second photovoltaic DC power supply 102 and the power bus, and a freewheeling transistor D21 connected in parallel with the output terminal of the second power module 402. In this implementation, the switching transistors S11 and S21 are configured as MOSFETs, and the freewheeling transistors D11 and D21 are configured as freewheeling diodes. The freewheeling transistor D11 provides a freewheeling channel.

[0049] The voltage control module 300 includes a reverse-biased diode Dinv and a voltage regulator unit. The voltage regulator unit includes a first output terminal and a second output terminal. The first power module 401 has an output terminal including a high-potential terminal and a low-potential terminal, with the low-potential terminal connected to a reference ground. The first output terminal of the voltage regulator unit is electrically connected to the high-potential terminal of the first power module 401 through the reverse-biased diode Dinv, and the second output terminal of the voltage regulator unit is electrically connected to the low-potential terminal of the first power module 401. In this implementation, the voltage regulator unit is configured as a low-dropout linear regulator (LDO). In other implementations, it can also be configured as a DC / DC converter, etc.

[0050] When the photovoltaic equipment is in standby mode, the main control module 200 controls the switches S11 and S21 to open, and the voltage regulator unit outputs a stable preset voltage (generally greater than the set value of the standby voltage of the photovoltaic equipment to compensate for the forward voltage drop of the anti-reverse diode Dinv and the freewheeling diode D21). The anti-reverse diode Dinv and the freewheeling diode D21 are turned on, and the first output terminal of the voltage regulator unit forms a loop through the anti-reverse diode Dinv, the external load, the freewheeling diode D21, and the reference ground, thereby maintaining the standby voltage of the photovoltaic equipment at the set value. When the photovoltaic equipment is working normally, the main control module 200 controls the switches S11 and S21 to close, and the output voltage Vout of the photovoltaic equipment is greater than the output voltage of the voltage control module 300. The anti-reverse diode Dinv and the freewheeling diode D21 are reverse-biased and cut off.

[0051] The first power module 401 also includes a capacitor Cout1 connected in parallel at its output terminal to stabilize the output voltage at its output terminal; the second power module 402 also includes a capacitor Cout2 connected in parallel at its output terminal to stabilize the output voltage at its output terminal.

[0052] As one implementation method, the voltage regulator unit provides feedback regulation of the output voltage Vout of the photovoltaic device to stabilize the standby voltage of the photovoltaic device at a set value.

[0053] As one implementation method, such as Figure 4 As shown, with Figure 3 Compared to the implementation shown, the switching transistors and freewheeling transistors in the first power module 401 and the second power module 402 are both set as MOSFETs. A current sensing resistor Rcs is also connected in series between the first power module 401 and the second power module 402 to detect the power bus current and realize current monitoring.

[0054] When the photovoltaic device is in standby mode, the main control module 200 controls the switches S11 and S21 to open, controls the freewheeling diode D11 to open, and controls the freewheeling diode D21 to open, causing the output of the second power module 402 to be short-circuited. The low potential terminal (negative terminal) of the photovoltaic device's output is pulled to the reference ground potential, and the voltage regulator unit outputs a stable preset voltage. The first output terminal of the voltage regulator unit forms a loop through the anti-reverse diode Dinv, the external load, the freewheeling diode D21, and the reference ground, thereby maintaining the output voltage (i.e., standby voltage) of the photovoltaic device in standby mode at the set value. When the photovoltaic device is working normally, the main control module 200 controls the switches S11 and S21 to close, controls the freewheeling diodes D11 and D21 to work normally, the output voltage Vout of the photovoltaic device is greater than the output voltage of the voltage control module 300, and the anti-reverse diode Dinv is reverse-biased and cut off.

[0055] As one implementation method, such as Figure 5As shown, with Figure 4 Compared to the implementation shown, the main control module 200 outputs an enable signal EN to the voltage control module 300. The enable signal EN controls the working state of the voltage control module 300. When the photovoltaic device is in standby mode, the main control module 200 enables the voltage control module 300 through the enable signal EN, causing the voltage control module 300 to start working. When the photovoltaic device is working normally, the main control module 200 controls the voltage control module 300 to stop working through the enable signal EN, so as to reduce the loss of the voltage control module 300. Other similarities will not be described in detail.

[0056] The photovoltaic equipment can be a photovoltaic optimizer, and the first power module 401 and the second power module 402 can specifically be a buck circuit, a boost circuit, a buck-boost circuit, etc. As one implementation method, such as... Figure 6 As shown, the first power module 401 includes switching transistors S31 and S32 and an inductor L1, and the second power module 402 includes switching transistors S41 and S42 and an inductor L2. Switches S31 and S41 can be used to control the connection between the first photovoltaic DC power supply 101 and the second photovoltaic DC power supply 102 and the power bus. Switches S32 and S42 can be used to provide a freewheeling path. When the photovoltaic device is in standby mode, the main control module 200 provides an enable signal EN to enable the power supply. The voltage control module 300 controls the switching transistors S31, S32, and S41 to turn off, disconnecting the first photovoltaic DC power supply 101 and the second photovoltaic DC power supply 102 from the power bus. The main control module 200 controls the switching transistor S42 to turn on, and the output of the second power module 402 is short-circuited. The potential of the low potential terminal (negative terminal) of the photovoltaic device output terminal is pulled to the reference ground potential through the switching transistor S42 and the inductor L2, so that the voltage control module 300 can maintain the standby voltage of the photovoltaic device at the set value.

[0057] When the photovoltaic equipment is in normal operation, the main control module 200 controls the voltage control module 300 to stop working, and achieves power control by controlling the conduction and cutoff of switching transistors S31, S32, S41 and S42. The output voltage Vout of the photovoltaic equipment is greater than the output voltage of the voltage control module 300, and the reverse protection diode Dinv is reverse cut off.

[0058] As one implementation method, such as Figure 7 As shown, with Figure 2Compared to the implementation shown, the multi-input photovoltaic device also includes a second power module 402', the input terminal of which is connected to a third photovoltaic DC power supply 103. The second power module 402, the first power module 401 and the second power module 402' are connected in series in sequence. The main control module 200 is also used to control the working state of the second power module 402'.

[0059] When the photovoltaic equipment is in standby mode, the main control module 200 controls the first power module 401, the second power module 402, and the second power module 402' to disconnect from the corresponding first photovoltaic DC power supply 101, the second photovoltaic DC power supply 102, and the third photovoltaic DC power supply 103. At the same time, the main control module 200 provides an enable signal to enable the voltage control module 300 and controls the outputs of the second power module 402 and the second power module 402' to be short-circuited, thereby maintaining the standby voltage of the photovoltaic equipment at a set value. In some other embodiments, the number of second power modules can be arbitrarily set as needed, such as 3 or 4.

[0060] As one implementation, this embodiment also proposes a standby voltage control method for multi-input photovoltaic devices, used to control the output voltage of any of the multi-input photovoltaic devices described above in standby mode, including:

[0061] A voltage control module is connected in parallel with the output of the first power module. This voltage control module controls the standby voltage of the photovoltaic device and maintains the standby voltage of the photovoltaic device at a set value.

[0062] The first power module is connected in series with at least one second power module, and is used to control the output power of the photovoltaic DC power supply connected to its input terminal.

[0063] Furthermore, when the photovoltaic equipment is in standby mode, the output of the second power module is short-circuited.

[0064] Furthermore, when the photovoltaic device is in standby mode, an enable signal is provided to the voltage control module to enable the voltage control module.

[0065] Furthermore, when the photovoltaic equipment is in standby mode, the switching transistor and freewheeling transistor of the first power module are disconnected, the switching transistor of the second power module is disconnected, and the freewheeling transistor is turned on, so that the output of the corresponding second power module is short-circuited.

[0066] As one implementation, this embodiment also proposes a photovoltaic system, including at least one photovoltaic string, the photovoltaic string including multiple photovoltaic devices connected in series and a photovoltaic DC power supply connected to the photovoltaic devices respectively, wherein the photovoltaic devices are configured as multi-input photovoltaic devices as described in any of the above implementations.

[0067] The standby voltage of each photovoltaic device in a photovoltaic string is a set value. Therefore, the string voltage of the photovoltaic string is the product of the standby voltage set value of the photovoltaic device and the number of photovoltaic devices connected in series. By measuring the string voltage of the photovoltaic string, the number of photovoltaic devices in the photovoltaic string can be calculated.

[0068] In summary, the embodiments of the present invention control the standby voltage of the photovoltaic equipment to remain stable at a set value in the standby state through the main control module and the voltage control module. This facilitates the verification of the number and connection relationship of photovoltaic equipment in each photovoltaic string by measuring the output voltage of the photovoltaic string during installation. Furthermore, the solution of this application simplifies the control of the standby voltage of the photovoltaic equipment and reduces product costs.

[0069] The technical solution of the present invention has been described above with reference to specific embodiments. However, it should be noted that the above descriptions are only for explaining the solution of the present invention and should not be construed as a specific limitation on the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can conceive of other specific embodiments or equivalent substitutions of the present invention without creative effort, and all such embodiments or substitutions will fall within the scope of protection of the present invention.

Claims

1. A multiple-input photovoltaic device, characterized by, The application relates to a multi-input photovoltaic device, comprising: a first power module and at least one second power module connected in series, the first power module and the second power module being used for controlling output power of photovoltaic direct-current power sources connected with input ends of the first power module and the second power module respectively; a voltage control module connected in parallel with an output end of the first power module, the voltage control module being used for controlling standby voltage of the photovoltaic device and maintaining the standby voltage of the photovoltaic device at a set value; a main control module connected with the first power module and the second power module respectively, the main control module being used for controlling working states of the first power module and the second power module, when the photovoltaic device is in a standby state, the main control module controls output short circuit of the second power module, so that output voltage of the output end of the first power module is equal to output voltage of the photovoltaic device, and the output voltage of the photovoltaic device is equal to the standby voltage.

2. The multiple-input photovoltaic device of claim 1, wherein, The main control module is further connected with the voltage control module, and when the photovoltaic device is in the standby state, an enable signal is provided to the voltage control module to enable the voltage control module.

3. The multiple-input photovoltaic device of claim 1, wherein, The output end of the first power module comprises a high potential end and a low potential end, and the low potential end is connected with a reference ground.

4. The multiple-input photovoltaic device of claim 1, wherein, The voltage control module comprises an anti-reverse diode and a voltage stabilizing unit connected in series, the voltage stabilizing unit is used for providing a preset voltage, and an output end of the voltage stabilizing unit is connected with the output end of the first power module through the anti-reverse diode.

5. The multiple-input photovoltaic device of claim 1, wherein, The first power module and the second power module comprise a switch tube used for controlling communication or disconnection of corresponding photovoltaic direct-current power sources with a power bus and a freewheeling tube used for providing a freewheeling channel, when the photovoltaic device is in the standby state, the main control module controls the switch tube and the freewheeling tube of the first power module to be disconnected, the switch tube of the second power module to be disconnected and the freewheeling tube to be conducted, so that the output of the corresponding second power module is short-circuited.

6. The multiple-input photovoltaic device of claim 1, wherein, The application further comprises: an auxiliary power supply module used for taking power from the photovoltaic direct-current power sources connected with the input ends of the first power module and / or the second power module to supply power to the main control module and the voltage control module.

7. The multiple-input photovoltaic device of claim 1, wherein, The application further comprises: a current detection resistor connected in series between the first power module and the second power module, one end of the current detection resistor being connected with a reference ground, and the current detection resistor being used for detecting power bus current.

8. A method for controlling the standby voltage of a multi-input photovoltaic device, characterized in that, A method for controlling standby voltage of a multi-input photovoltaic device as claimed in any one of claims 1-7, comprising: connecting a voltage control module in parallel with an output end of a first power module, the voltage control module being used for controlling standby voltage of the photovoltaic device and maintaining the standby voltage of the photovoltaic device at a set value, wherein the first power module and at least one second power module are connected in series, and are used for controlling output power of photovoltaic direct-current power sources connected with input ends of the first power module and the second power module respectively.

9. A photovoltaic system characterized by, The application relates to a multi-input photovoltaic device, comprising: at least one photovoltaic string, the photovoltaic string comprising a plurality of photovoltaic devices connected in series and photovoltaic direct-current power sources connected with the photovoltaic devices correspondingly, the photovoltaic devices being set as the multi-input photovoltaic device as claimed in any one of claims 1-7.

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