Power supply system and its control method

Abstract

This application provides a power supply system and a method for controlling the same. The power supply system includes at least four DC converters and an inverter. The inverter includes at least two DC / DC circuits, the input terminal of each DC / DC circuit being connected to the output terminals of at least two DC converters, the output terminals of at least two DC converters being connected in series, and the input terminal of each DC converter being connected to a photovoltaic module corresponding to the DC converter. The inverter controls the system so that the input terminal of one of the at least two DC / DC circuits is short-circuited. In response to the short-circuiting of the input terminal of one of the at least two DC / DC circuits, the at least four DC converters detect whether the output operating parameters of the at least four DC converters conform to a preset parameter range, and assign a number to the DC converters among the at least four DC converters whose output operating parameters conform to the preset parameter range. This effectively reduces the time required to assign numbers to all DC converters.

Description

Technical Field

[0001] This application relates to the field of power supply technology, and particularly relates to a power supply system and its control method.

Background Art

[0002] In the case of a solar power generation power supply system, the output terminals of each solar power generation module, or the output terminals of a plurality of solar power generation modules that are connected in series and / or in parallel, are usually connected to a solar power generation optimizer having an independent maximum power point tracking (MPPT) function. The output terminals of a plurality of solar power generation optimizers are connected to an inverter based on a specific series / parallel combination, realizing the MPPT function at the solar power generation module level and maximizing the energy yield of the system.

[0003] String numbering is typically performed in photovoltaic optimizers to better control them. Currently, string numbering is mainly performed in the photovoltaic optimizers in the photovoltaic system shown in Figure 1 in the following way: After the photovoltaic system is powered on, the inverter 20 is in a standby off-grid state, and all photovoltaic optimizers (i.e., photovoltaic optimizers 111,..., photovoltaic optimizer 11m, photovoltaic optimizer 121,..., and photovoltaic optimizer 12n) are powered off by default; the string number of all photovoltaic optimizers is 0 by default. The inverter 20 randomly selects a photovoltaic optimizer (e.g., photovoltaic optimizer 111) and sends a voltage adjustment command to photovoltaic optimizer 111, and as a result, photovoltaic optimizer 111 controls its output voltage to 20V according to the voltage adjustment command. Next, the inverter 20 determines which solar power string the solar power optimizer 111 is positioned in, based on the input voltage sampling value of the inverter 20 (i.e., the voltage of the solar power string). For example, if the inverter 20 knows that the voltage of photovoltaic string 11 is approximately 20V and the voltage of solar power string 12 is approximately 0V, the inverter 20 determines that the solar power optimizer 111 is positioned in solar power string 11 and sends a string number setting command to the solar power optimizer 111. As a result, the solar power optimizer 111 sets its own string number to the string number of solar power string 11 in accordance with the string number setting command. Next, after the photovoltaic optimization device 111 has completed setting the string number, the inverter 20 controls the photovoltaic optimization device 111 to power off, selects one of the (m+n) photovoltaic optimizers other than photovoltaic optimizer 111, and sends a voltage adjustment command to the photovoltaic optimizer.The above steps are repeated until all solar power optimizers have completed string number configuration.

[0004] In the aforementioned string number setting method for solar power optimizers, the inverter 20 controls only one solar power optimizer at a time to set the string number. As the number of solar power optimizers connected to the input terminal of the inverter increases, the duration spent by all solar power optimizers to complete the string number setting increases accordingly. Therefore, it is particularly important to consider how to reduce the duration for setting the string number of the solar power optimizers. [Overview of the project]

[0005] This application provides a power supply system and a control method thereof for reducing the duration required to set the number of all DC converters.

[0006] According to a first aspect, the present application provides a power supply system. The power supply system includes at least four DC converters and an inverter. The inverter includes at least two DC / DC circuits, the input terminal of each DC / DC circuit in the at least two DC circuits is connected to the output terminals of at least two DC converters, the output terminals of the at least two DC converters are connected in series, and the input terminal of each DC converter in the at least four DC converters is connected to a photovoltaic module corresponding to the DC converter. The inverter controls the input terminal of one of the at least two DC / DC circuits to be short-circuited. In response to the short-circuiting of the input terminal of one of the at least two DC / DC circuits, the at least four DC converters detect whether the output operating parameters of the at least four DC converters conform to a preset parameter range; a number is assigned to one or more DC converters whose output operating parameters conform to the preset parameter range of the at least four DC converters, the number indicating that one or more DC converters are connected to one DC / DC circuit. Therefore, after the inverter controls the input terminal of one DC / DC circuit to be short-circuited, numbers can be simultaneously assigned to all DC converters whose output operating parameters conform to a preset parameter range, i.e., DC converters connected to the DC / DC circuit with its input terminal short-circuited. In other words, in the power supply system provided in this application, numbers are assigned to the DC converters based on the DC / DC circuit in the inverter. Compared to assigning numbers to DC converters one by one, the method of the power supply system provided in this application can effectively reduce the overall duration required to assign numbers to all DC converters.

[0007] In the first embodiment, in the first possible implementation, the inverter further controls the input terminal of one DC / DC circuit in at least two DC / DC circuits to be short-circuited, and then transmits a broadcast instruction to at least four DC converters. In response to receiving the broadcast instruction, the at least four DC converters detect whether the output operating parameters of the at least four DC converters conform to a predetermined parameter range, and number one or more DC converters whose output operating parameters conform to the predetermined parameter range in the at least four DC converters. In this implementation, upon receiving the broadcast instruction transmitted by the inverter, each of the at least four DC converters performs the corresponding operation for numbering, and the inverter transmits the broadcast instruction to all of the at least four DC converters. Thus, it can be ensured that all DC converters connected to the input terminals of the same DC / DC circuit complete numbering essentially simultaneously; if there are multiple DC converters connected to the same DC / DC circuit, this effectively reduces the time it takes for all DC converters connected to the same DC / DC circuit to complete numbering.

[0008] With respect to a first possible implementation of the first embodiment, in a second possible implementation, the broadcast instruction includes the serial number of a DC / DC circuit whose input terminal is currently shorted. At least four DC converters set a number for one or more DC converters whose output operating parameters fit within a pre-set parameter range of at least four DC converters, based on the serial number of the DC / DC circuit whose input terminal is currently shorted.

[0009] With respect to a first possible implementation of the first embodiment, in a third possible implementation, at least two DC converters and photovoltaic modules corresponding to at least two DC converters form a photovoltaic string, and the broadcast instruction includes the string number of the photovoltaic string connected to the input terminal of a DC / DC circuit whose input terminal is currently short-circuited. At least four DC converters set the number of one or more DC converters whose output operating parameters conform to a pre-set parameter range of at least four DC converters, based on the string number of the photovoltaic string connected to the input terminal of a DC / DC circuit whose input terminal is currently short-circuited. In this implementation embodiment, the number of the DC converters includes the string number of the string in which the DC converters are located, and as a result, the inverter can subsequently perform precise control of the photovoltaic string through control of the DC converters based on the number of the DC converters.

[0010] In any one of the first or third possible implementations of the first embodiment, in a fourth possible implementation, the inverter sequentially controls the input terminal of at least two DC / DC circuits to exit the short-circuit state after the input terminal has been short-circuited, until all at least four DC converters have completed numbering. In this implementation, the inverter is only required to determine whether all DC converters in the power supply system have completed numbering by determining whether the currently controlled DC / DC circuit is the last DC / DC circuit in a pre-set sequence. In this way, it is possible to know whether all DC converters in the power supply system have completed numbering without communicating with the DC converters. This can improve the efficiency of numbering the DC converters in the power supply system.

[0011] With respect to a fourth possible implementation of the first embodiment, in a fifth possible implementation, the inverter controls the input terminal of one DC / DC circuit in at least two DC / DC circuits that is connected to a DC converter that does not have a setting number, and after the DC converter that does not have a setting number sets a number based on the serial number of the DC / DC circuit whose input terminal is now shorted, the inverter controls the input terminal of one DC / DC circuit in at least two DC / DC circuits. 1 The DC / DC circuit is controlled to ensure that the input terminal of a DC / DC circuit connected to a DC converter having a set number is not short-circuited. In this implementation, the power supply system sets the numbers of all DC converters connected to all DC / DC circuits in the inverter (i.e., all DC converters in the power supply system) by simultaneously performing the corresponding numbering operation for all DC converters connected to the same DC / DC circuit. This effectively reduces the time required for all DC converters in the power supply system to complete the numbering process.

[0012] With respect to any one of the first to fifth possible implementations of the first embodiment, in a sixth possible implementation, at least four DC converters are controlled so that the output voltage of each DC converter is a first preset voltage value before responding to a short-circuiting of the input terminal of one DC / DC circuit in at least two DC / DC circuits, the first preset voltage value being greater than or equal to a first voltage threshold and less than a second voltage threshold, the first voltage threshold being the minimum detectable output voltage value of the DC converter and the second voltage threshold being the maximum output voltage value of the DC converter. It will be understood that the power supply system controls the DC converters to output small voltage values, and as a result the DC converters are in a low-power operating state, and the inverter is more easily controlled to successfully short-circuit the input terminal of the inverter's internal DC / DC circuit. This improves the accuracy of setting the string number by the DC converters thereafter.

[0013] In any one of the first to fifth possible implementations of the first embodiment, in the seventh possible implementation, at least four DC converters further control their respective output currents to a first preset current value before responding to a short circuit at the input terminal of one DC / DC circuit in at least two DC / DC circuits, the first preset current value being less than or equal to a first current threshold, the first current threshold being the maximum output current value of the DC converter. If the first preset current value is a small current value within the current range less than or equal to the first current threshold, it will be understood that the power supply system controls the DC converters to output a small current, and as a result the DC converters are in a low-power operating state, and the inverter is more likely to successfully control the short circuit at the input terminal of the inverter's internal DC / DC circuit. This improves the accuracy of setting the string number by the DC converters thereafter.

[0014] In any one of the first to fifth possible implementations of the first embodiment, in the eighth possible implementation, at least four DC converters are controlled so that their respective output voltages and output currents are a first preset voltage value and a first preset current value, respectively, before responding to a short circuit at the input terminal of one DC / DC circuit in at least two DC / DC circuits, the first preset voltage value is greater than or equal to a first voltage threshold and less than a second voltage threshold, the first preset current value is less than or equal to a first current threshold, the first voltage threshold is the minimum detectable output voltage value of the DC converter, the second voltage threshold is the maximum output voltage value of the DC converter, and the first current threshold is the maximum output current value of the DC converter. It will be understood that the DC converters are capable of controlling the output voltage or output current, and as a result the DC converters are in a low-power operating state, and the inverter is better able to successfully control the short circuit at the input terminal of the internal DC / DC circuit. This improves the accuracy of setting the string number by the DC converters thereafter.

[0015] In any one of the first to eighth possible implementations of the first embodiment, and in the ninth possible implementation, the output operating parameters include output voltage or output current. At least four DC converters detect whether their respective output voltages are less than a third voltage threshold or whether their respective output currents are greater than a second current threshold in response to the input terminal of one DC / DC circuit in at least two DC / DC circuits being short-circuited. It will be understood that a DC converter can determine whether it is connected to a DC / DC circuit with its input terminals short-circuited based solely on the output voltage or output current of the DC converter. Thus, the determination method is simple, which helps to improve the efficiency of the DC converter.

[0016] In any one of the first to eighth possible implementations of the first embodiment, in a tenth possible implementation, the output operating parameters include output voltage or output current. At least four DC converters detect whether their respective output voltages are less than a third voltage threshold and whether their respective output currents are greater than a second current threshold, in response to the input terminal of one DC / DC circuit in at least two DC / DC circuits being short-circuited. It will be understood that the DC converters can determine whether they are connected to a DC / DC circuit with a short-circuited input terminal not only based on the output voltage or output current of the DC converters, but also based on the two conditions of the output voltage and output current of the DC converters. Thus, various determination methods exist. There is a high degree of flexibility.

[0017] With respect to any one of the first to the tenth possible implementations of the first embodiment, in the eleventh possible implementation, the inverter controls the input terminal of one of the at least two DC / DC circuits to exit the short-circuit state after the numbering is complete of the DC converters connected to the input terminal of one of the at least two DC / DC circuits. If, after the input terminal of one of the at least two DC / DC circuits has exited the short-circuit state, the number of DC converters connected to the input terminal of one of the at least two DC / DC circuits is greater than a quantity threshold, this indicates that the photovoltaic string in which the DC converters connected to the input terminal of one of the at least two DC / DC circuits are located is a long string, in which case the inverter controls the output voltage of the DC converters connected to the input terminal of one of the at least two DC / DC circuits to be less than a fourth voltage threshold, thereby ensuring that the output voltage of the long string does not exceed the maximum input voltage value of the inverter, and thereby improving the stability of the inverter.

[0018] With respect to any one of the first to the tenth possible implementations of the first embodiment, in the twelfth possible implementation, the inverter further controls the input terminal of one of the at least two DC / DC circuits to escape the short-circuit condition after the DC converters connected to the input terminal of one of the at least two DC / DC circuits have completed numbering. After the input terminal of one of the at least two DC / DC circuits has escaped the short-circuit condition, in response to the quantity of DC converters connected to the input terminal of one of the at least two DC / DC circuits being less than or equal to a quantity threshold, this indicates that the photovoltaic string in which the DC converters connected to the input terminal of one of the at least two DC / DC circuits are located is a short string, in which case the inverter controls the output voltage of the DC converters connected to the input terminal of one of the at least two DC / DC circuits to be less than a fifth voltage threshold. Since the fifth voltage threshold is greater than the fourth voltage threshold, we can see that the voltage limit of the DC converter in short strings is higher than the voltage limit of the DC converter in long strings. This guarantees high operating efficiency of the DC converter in short strings.

[0019] With respect to any one of the first to twelfth possible implementations of the first embodiment, in a thirteenth possible implementation, the inverter further includes a DC bus and an inverter circuit, wherein the output terminals of at least two DC / DC circuits are connected in parallel to the DC bus, the input terminals of the inverter circuit are connected to the DC bus, and the output terminals of the inverter circuit are connected to the output terminals of the inverter.

[0020] According to a second aspect, the present application provides a control method for a power supply system. The method includes: A step of controlling the input terminal of one of at least two DC / DC circuits to be short-circuited; A step of detecting whether the output operating parameters of at least four DC converters conform to a predetermined parameter range in response to the input terminal of one DC / DC circuit being short-circuited in at least two DC / DC circuits; and The method is applicable to a power supply system comprising the step of assigning a number to one or more DC converters whose output operating parameters conform to a predetermined parameter range of at least four DC converters, wherein the number indicates that one or more DC converters are connected to a single DC / DC circuit. The power supply system comprises at least four DC converters and an inverter. The inverter comprises at least two DC / DC circuits, the input terminal of each DC / DC circuit in the at least two DC / DC circuits being connected to the output terminals of at least two DC converters, the output terminals of the at least two DC converters being connected in series, and the input terminal of each DC converter in the at least four DC converters being connected to a photovoltaic module corresponding to the DC converter.

[0021] In a second embodiment, in the first possible implementation, the inverter further controls the input terminal of one DC / DC circuit in at least two DC / DC circuits to be short-circuited, and then transmits a broadcast instruction to at least four DC converters. In response to receiving the broadcast instruction, the at least four DC converters detect whether the output operating parameters of the at least four DC converters conform to a predetermined parameter range, and assign a number to one or more DC converters whose output operating parameters conform to the predetermined parameter range in the at least four DC converters.

[0022] With respect to a first possible implementation of the second embodiment, in the second possible implementation, the broadcast instruction includes the serial number of a DC / DC circuit whose input terminal is currently shorted. At least four DC converters set a number for one or more DC converters whose output operating parameters fit within a pre-set parameter range of at least four DC converters, based on the serial number of the DC / DC circuit whose input terminal is currently shorted.

[0023] With respect to a first possible implementation of the second embodiment, in a third possible implementation, at least two DC converters and photovoltaic modules corresponding to at least two DC converters form a photovoltaic string, and the broadcast instruction includes the string number of the photovoltaic string connected to the input terminal of a DC / DC circuit whose input terminal is currently short-circuited. At least four DC converters set the number of one or more DC converters whose output operating parameters fit within a pre-set parameter range of at least four DC converters, based on the string number of the photovoltaic string connected to the input terminal of a DC / DC circuit whose input terminal is currently short-circuited.

[0024] In any one of the second or third possible implementations of the second embodiment, in a fourth possible implementation, the inverter sequentially controls the input terminal of one DC / DC circuit in at least two DC / DC circuits to exit the short-circuit state after the input terminal has been short-circuited, until all at least four DC converters have completed numbering.

[0025] With respect to a fourth possible implementation of the second embodiment, in a fifth possible implementation, the inverter controls the input terminal of one DC / DC circuit in at least two DC / DC circuits that is connected to a DC converter that does not have a setting number, and after the DC converter that does not have a setting number sets a number based on the serial number of the DC / DC circuit whose input terminal is now shorted, the inverter controls the input terminal of one DC / DC circuit in at least two DC / DC circuits. 1 A DC / DC circuit that is connected to a DC converter having a setting number controls the input terminal of the DC / DC circuit so as to exit the short-circuit state.

[0026] Regarding any one of the second aspect to the fifth possible implementation of the second aspect, in a sixth possible implementation, at least four DC converters control their respective output voltages to be a first preset voltage value before responding to the input terminal of one DC / DC circuit in at least two DC / DC circuits being short-circuited. The first preset voltage value is greater than or equal to a first voltage threshold and less than a second voltage threshold. The first voltage threshold is the minimum detectable output voltage value of the DC converter, and the second voltage threshold is the maximum output voltage value of the DC converter.

[0027] Regarding any one of the second aspect to the fifth possible implementation of the second aspect, in a seventh possible implementation, at least four DC converters further control their respective output currents to be a first preset current value before responding to the input terminal of one DC / DC circuit in at least two DC / DC circuits being short-circuited. The first preset current value is less than or equal to a first current threshold, and the first current threshold is the maximum output current value of the DC converter.

[0028] Regarding any one of the second aspect to the fifth possible implementation of the second aspect, in an eighth possible implementation, at least four DC converters control their respective output voltages and output currents to be a first preset voltage value and a first preset current value respectively before responding to the input terminal of one DC / DC circuit in at least two DC / DC circuits being short-circuited. The first preset voltage value is greater than or equal to a first voltage threshold and less than a second voltage threshold, the first preset current value is less than or equal to a first current threshold, the first voltage threshold is the minimum detectable output voltage value of the DC converter, the second voltage threshold is the maximum output voltage value of the DC converter, and the first current threshold is the maximum output current value of the DC converter.

[0029] In any one of the second to eighth possible implementations of the second embodiment, in the ninth possible implementation, the output operating parameters include output voltage or output current. At least four DC converters detect whether their respective output voltages are less than a third voltage threshold or whether their respective output currents are greater than a second current threshold, in response to the input terminal of one of the DC / DC circuits being short-circuited in at least two DC / DC circuits.

[0030] In any one of the second to eighth possible implementations of the second embodiment, in the tenth possible implementation, the output operating parameters include output voltage or output current. At least four DC converters detect whether their respective output voltages are less than a third voltage threshold and whether their respective output currents are greater than a second current threshold, in response to the input terminal of one DC / DC circuit in at least two DC / DC circuits being short-circuited.

[0031] With respect to any one of the possible implementations of the second to the tenth possible implementation of the second embodiment, in the eleventh possible implementation, the inverter controls the input terminal of one of the at least two DC / DC circuits to exit the short-circuit state after the numbering is complete of the DC converters connected to the input terminal of one of the at least two DC / DC circuits. After the input terminal of one of the at least two DC / DC circuits has exited the short-circuit state, if the quantity of DC converters connected to the input terminal of one of the at least two DC / DC circuits is greater than a quantity threshold, the inverter controls the output voltage of the DC converters connected to the input terminal of one of the at least two DC / DC circuits to be less than a fourth voltage threshold.

[0032] With respect to any one of the possible implementations of the second to the tenth possible implementation of the second embodiment, in the twelfth possible implementation, the inverter further controls the input terminal of one of the at least two DC / DC circuits to escape the short-circuit condition after the DC converters connected to the input terminal of one of the at least two DC / DC circuits have completed numbering. After the input terminal of one of the at least two DC / DC circuits has escaped the short-circuit condition, in response that the quantity of DC converters connected to the input terminal of one of the at least two DC / DC circuits is less than or equal to a quantity threshold, the inverter controls the output voltage of the DC converters connected to the input terminal of one of the at least two DC / DC circuits to be less than a fifth voltage threshold.

[0033] It should be understood that cross-referencing is permitted for the implementation and beneficial effects of the aforementioned embodiments of this application. [Brief explanation of the drawing]

[0034] [Figure 1] Figure 1 shows the structure of a conventional solar power generation system.

[0035] [Figure 2] Figure 2 is a diagram illustrating the application scenario of the power supply system described in this application.

[0036] [Figure 3] Figure 3 is a diagram illustrating the structure of the power supply system according to this application.

[0037] [Figure 4] Figure 4 is a control sequence diagram of the DC converter according to this application.

[0038] [Figure 5] Figure 5 is a schematic flowchart of the control method for a power supply system according to the present application.

[0039] [Figure 6A] Figure 6A is another schematic flowchart of the control method for a power supply system according to the present application. [Figure 6B] Figure 6B is another schematic flowchart of the control method for a power supply system according to the present application. [Modes for carrying out the invention]

[0040] The power supply system provided in this application is applicable to multiple application areas, such as the fields of new energy, smart microgrids, power transmission and distribution, new energy (e.g., solar power grid connection), solar power generation, and solar energy storage and generation. The power supply system provided in this application is applicable to different application scenarios, such as solar power supply scenarios (including large-scale solar power station scenarios, small and medium-scale distributed solar power station scenarios, and residential solar power system scenarios), and solar energy storage and power supply scenarios (including large-scale solar energy storage plant scenarios, small and medium-scale distributed solar energy storage plant scenarios, and residential solar energy storage and generation system scenarios). The following explanation will use the solar power supply scenario as an example.

[0041] Figure 2 is a diagram illustrating an application scenario of the power supply system according to the present application. In the photovoltaic power supply scenario, the power supply system and DC converter provided in the present application may be the photovoltaic power supply system and photovoltaic optimizer shown in Figure 2, respectively. The photovoltaic system includes five photovoltaic optimizers and an inverter. The input terminal of each photovoltaic optimizer is connected to one photovoltaic module corresponding to the photovoltaic optimizer, and the five photovoltaic optimizers and the five photovoltaic modules connected to the input terminals of the five photovoltaic optimizers form a first photovoltaic string and a second photovoltaic string. Optionally, the input terminal of each photovoltaic optimizer may be further connected to multiple photovoltaic modules. Specifically, the output terminals of multiple photovoltaic modules may be connected in series and / or in parallel and then connected to the input terminal of one photovoltaic optimizer. The number of photovoltaic modules connected to the input terminals of all photovoltaic optimizers may be the same or different. This is not limited in the present application. The inverter includes a first DC / DC circuit, a second DC / DC circuit, and an inverter circuit. The first photovoltaic string includes two photovoltaic modules and two photovoltaic optimizers, the output terminal of one photovoltaic optimizer in the first photovoltaic string connected in series with the output terminal of the other photovoltaic optimizer in the first photovoltaic string, and then connected with the input terminal of the first DC / DC circuit. The second solar power string includes three solar modules and three solar power optimizers. The output terminal of one solar power optimizer in the second solar power string is connected in series with the output terminals of the other two solar power optimizers in the second solar power string, and then with the input terminals of the second DC / DC circuit. The output terminals of the first DC / DC circuit and the second DC / DC circuit are connected in parallel with the input terminals of the inverter circuit, and the output terminals of the inverter circuit are connected to an AC power grid or a household device via the inverter's output terminals.

[0042] After the solar power supply system is powered on (in other words, after the inverter is connected to the AC power grid), the inverter controls each solar optimizer to output voltage and / or current. After each solar optimizer has output voltage and / or current, the inverter controls the input terminals of one DC / DC circuit in the first DC / DC circuit and one DC / DC circuit in the second DC / DC circuit to be short-circuited. If the input terminals of one DC / DC circuit in the two DC / DC circuits are short-circuited, each of the five solar optimizers mentioned above detects whether the output operating parameters of the solar optimizer fit within a pre-set parameter range, and if the output operating parameters of the solar optimizer fit within the pre-set parameter range, it sets a number for the solar optimizer, which indicates that one or more solar optimizers whose output operating parameters fit within the pre-set parameter range are connected to the DC / DC circuit with the short-circuited input terminals. Next, after the numbers of all photovoltaic optimizers in the photovoltaic power supply system are set based on the steps described above, each photovoltaic optimizer performs MPPT on the photovoltaic modules connected to it, and the DC currents output by the photovoltaic optimizers in the same photovoltaic string are collected and then output to the inverter. The inverter performs DC conversion on the DC currents generated by the photovoltaic string connected to the inverter's input terminal using its internal DC / DC circuit, and outputs the DC obtained by the DC conversion to the inverter circuit. The inverter then controls the inverter circuit to invert the DC input from the inverter's input terminal and the DC obtained by the DC conversion, and supplies power to various power-consuming devices such as the AC power grid or AC loads (e.g., household devices). Thus, it can be seen that after the inverter is controlled to short-circuit the input terminal of the DC / DC circuit, the numbers of all photovoltaic optimizers connected to the DC / DC circuit with short-circuited input terminals may be set simultaneously.In other words, in the numbering method provided in this application, the number of photovoltaic optimizers is set based on the DC / DC circuit in the inverter. Compared to the method of numbering each photovoltaic optimizer individually, the method for a photovoltaic power supply system provided in this application can effectively reduce the time required to number all photovoltaic optimizers. The foregoing description is merely an example of application scenarios for the power supply system provided in this application, and is not exhaustive. Application scenarios are not limited in this application.

[0043] The following describes an example of the operating principle of the power supply system provided in this application, with reference to Figures 3 and 4.

[0044] Figure 3 is a diagram of the structure of the power supply system according to the present application. As shown in Figure 3, the power supply system 1 includes m DC converters and an inverter 20. The m DC converters include DC converter 111, DC converter 112,..., DC converter 11a,..., DC converter 1n1, DC converter 1n2,..., DC converter 1nb. The m DC converters are each connected to m photovoltaic modules that correspond to the m DC converters in a one-to-one manner, and the m photovoltaic modules include photovoltaic module 1101, photovoltaic module 1102,..., photovoltaic module 110a,..., photovoltaic module 1n01, photovoltaic module 1n02,..., and photovoltaic module 1n0b. The input terminal of the DC converter 111 is connected to the photovoltaic module 1101 corresponding to the DC converter 111. The input terminal of the DC converter 112 is connected to the photovoltaic module 1102, which is compatible with the DC converter 112,... The input terminal of the DC converter 11a is connected to the photovoltaic module 110a corresponding to the DC converter 11a,... The input terminal of DC converter 1n1 is connected to the photovoltaic module 1n01 corresponding to DC converter 1n1. The input terminal of DC converter 1n2 is connected to the corresponding solar power generation module 1n02, ... The input terminal of DC converter 1nb is connected to the photovoltaic module 1n0b, which corresponds to DC converter 1nb. m DC converters and m photovoltaic modules form n photovoltaic strings: photovoltaic string 11,..., and photovoltaic string 1n, where m is an integer greater than 3 and n is an integer greater than 1. Optionally, the correspondence between each of the m DC converters and the photovoltaic modules may be a one-to-many relationship. If one DC converter corresponds to multiple photovoltaic modules, the output terminals of the multiple photovoltaic modules are connected in series and / or parallel, and then connected to the input terminals of the DC converters.

[0045] The inverter 20 includes DC / DC circuits 2001,..., DC / DC circuit 200n, DC buses (i.e., positive DC bus Bus+ and negative DC bus Bus-), and inverter circuit 201. The input terminal of each DC / DC circuit is connected to the output terminals of at least two DC converters from among m DC converters, and the output terminals of at least two DC converters connected to the input terminal of each DC / DC circuit are connected in series. Specifically, the output terminals of DC converter 111, DC converter 112,..., and DC converter 11a are connected in series and then connected to the input terminal of DC / DC circuit 2001 via a first group of input terminals of inverter 20 (i.e., input terminals i21+ and i21-). The output terminals of DC converters 1n1, 1n2, ..., and 1nb are connected in series and then connected to the input terminals of DC / DC circuit 200n via the nth group of input terminals of inverter 20 (i.e., input terminals i2n+ and i2n-). The positive output terminals of DC / DC circuit 2001, ..., and DC / DC circuit 200n are all connected to the positive DC bus Bus+, and the negative output terminals of DC / DC circuit 2001, ..., and DC / DC circuit 200n are all connected to the negative DC bus Bus-. The positive and negative input terminals of inverter circuit 201 are connected to the positive DC bus Bus+ and the negative DC bus Bus-, respectively; the output terminals of inverter circuit 201 are connected to the AC power grid via the output terminals of inverter 20.

[0046] In the implementation configuration, after the power supply system 1 is powered on, the inverter 20 and all DC converters within the power supply system 1 are in their initial state. Specifically, the inverter 20 is in standby mode, all DC converters are powered off, the output voltage of each solar power generation string is 0 V, and the number of all DC converters is 0. Next, the inverter 20 controls each DC converter to enter a first operating state, and after all DC converters in the power supply system 1 have entered the first operating state, it controls the input terminal of one of the DC / DC circuits 2001,..., and 200n to be short-circuited. The following explanation will use the example where one of the DC / DC circuits 2001,..., and 200n is DC / DC circuit 2001. In response to the short-circuiting of the input terminal of DC / DC circuit 2001, each DC converter detects whether the output operating parameters of the DC converter fit within a preset parameter range. Each DC converter is assigned a number if its output operating parameters fit within a pre-set parameter range. This number indicates that the DC converter whose output operating parameters fit within the pre-set parameter range is connected to the DC / DC circuit 2001.

[0047] In an optional embodiment, the output operating parameters include the output voltage.

[0048] Specifically, after the power supply system 1 is powered on, the inverter 20 and all DC converters are in an initial state. The inverter 20 then sends a first operation command to each DC converter. Specifically, the first operation command here is a startup voltage adjustment command. Each DC converter controls its output voltage to a first preset voltage value (e.g., 20V) according to the received startup voltage adjustment command, and as a result, all DC converters are in a first operating state. The first preset voltage value is greater than or equal to a first voltage threshold V1 and less than a second voltage threshold V2. The first voltage threshold may be the minimum detectable output voltage value of the DC converter, and the minimum detectable output voltage value is determined based on the output voltage detection accuracy of the DC converter. The second voltage threshold may be the maximum output voltage value of the DC converter. For example, the first voltage threshold may be 5V. The second voltage threshold may be 80V. The first operating state also includes a low-power operating state and a high-power operating state. The DC converter may be adjusted to either a low-power or high-power operating state by adjusting the value of a first preset voltage within the voltage range [V1, V2). It will be understood that the power supply system controls the DC converter to output a small voltage value, resulting in the DC converter being in a low-power operating state, and the inverter will be more easily controlled to short-circuit the input terminals of the inverter's internal DC / DC circuit. This will improve the accuracy of setting the string number by the DC converter thereafter.

[0049] Optionally, the inverter 20 transmits a first operation command to each DC converter. Specifically, the first operation command here is a current adjustment command. Each DC converter controls its output current to a first preset current value (e.g., 3A) according to the received current adjustment command, and as a result, the DC converter enters a first operating state. The first preset current value is less than or equal to a first current threshold A1. The first current threshold may be the maximum output current value of the DC converter, for example, 15A. It should be understood that the DC converter may control only the output current value, and as a result, the DC converter will be in the first operating state. The control method is flexible. Also, if the first preset current value is a small current value within the current range (0, A1), the power supply system 1 controls the DC converter to output a small current, and as a result, the DC converter can enter a low-power operating state, and the inverter 20 can more easily control the inverter so that the input terminal of its internal DC / DC circuit is short-circuited. This will improve the accuracy of setting the numbers using a DC converter from now on.

[0050] Optionally, the inverter 20 transmits a first operating command to each DC converter. Specifically, the first operating command here includes a startup voltage adjustment command and a current adjustment command. Each DC converter controls its output voltage to a first preset voltage value according to the received startup voltage adjustment command, and controls its output current to a first preset current value according to the received current adjustment command, so that the DC converter enters a first operating state. The first preset voltage value is greater than or equal to a first voltage threshold and less than a second voltage threshold, and the first preset current value is less than or equal to a first current threshold. It will be understood that a DC converter can enter a first operating state by controlling either its output voltage or output current; or a DC converter can enter a first operating state by controlling both its output voltage and output current. Therefore, there are various ways to control the DC converters to enter a low-power operating state. The flexibility is high.

[0051] Next, after all DC converters have entered a first operating state, that is, after a first preset period from the time the inverter 20 transmits a first operating command to the DC converters, the inverter 20 controls the short circuit between the positive and negative input terminals of one of the n DC / DC circuits, DC / DC circuit 2001. For example, the inverter 20 can control the short circuit between the positive and negative input terminals of DC / DC circuit 2001 by controlling a controllable switch connected between the positive and negative input terminals of DC / DC circuit 2001 to turn on. After controlling the short circuit between the positive and negative input terminals of DC / DC circuit 2001, the inverter 20 transmits a broadcast instruction, i.e., a number setting instruction, to each DC converter. When each DC converter receives a numbering command, if the DC converter determines that the input terminal of one of the n DC / DC circuits is short-circuited, the DC converter detects whether its output voltage is less than a third voltage threshold, where the third voltage threshold is the minimum detectable output voltage value of the DC converter, e.g., 5V. Of the m DC converters, one or more DC converters whose output voltage is less than the third voltage threshold set a number for one or more DC converters according to the received numbering command.

[0052] Specifically, the number setting command includes the serial number of the DC / DC circuit whose input terminals are currently short-circuited, i.e., the serial number of DC / DC circuit 2001. Of the m DC converters, one or more DC converters whose output voltage is below the third voltage threshold, i.e., one or more DC converters whose output voltage is within the short-circuit voltage range, are numbered based on the serial number of DC / DC circuit 2001. For example, one or more DC converters whose output voltage is below the third voltage threshold are 、1 Number of DC converters to the serial number of DC / DC circuit 2001 Set the number to indicate that one or more DC converters are connected to the DC / DC circuit 2001.

[0053] Optionally, the numbering command carries the string number of the photovoltaic string connected to the input terminal of a DC / DC circuit whose input terminal is currently short-circuited (i.e., the string number of photovoltaic string 11). Of the m DC converters, one or more DC converters whose output voltage is below a third voltage threshold are numbered based on the string number of photovoltaic string 11. For example, one or more DC converters whose output voltage is below a third voltage threshold are numbered in the format "string number of photovoltaic string 11". This number indicates that the DC converter whose output voltage is below a third voltage threshold is connected to DC / DC circuit 2001 and is located within photovoltaic string 11 connected to DC / DC circuit 2001. The string number of the photovoltaic string may also be the ranking of the photovoltaic string among n photovoltaic strings. The string number of the photovoltaic string may be the same as or different from the serial number of the DC / DC circuit connected to the photovoltaic string. This is not limited to the present application.

[0054] In another optional embodiment, the output operating parameters include the output current.

[0055] Specifically, after the power supply system 1 is powered on, the inverter 20 and all DC converters are in an initial state. Next, the inverter 20 sends a first operation command to each DC converter, and each DC converter controls itself to enter a first operating state according to the first operation command it received. After all DC converters have entered the first operating state, that is, after a first preset period from the time the inverter 20 sent the first operation command to the DC converters, the inverter 20 controls a short circuit between the positive and negative input terminals of one of the n DC / DC circuits, DC / DC circuit 2001, and after controlling the short circuit between the positive and negative input terminals of DC / DC circuit 2001, it sends a broadcast instruction, i.e., a number setting command, to the DC converters. When each DC converter receives a numbering command, if the DC converter determines that the input terminal of one of the n DC / DC circuits is short-circuited, the DC converter detects whether the output current of the DC converter is greater than a second current threshold, where the second current threshold may be the minimum detectable output current value of the DC converter, and the minimum detectable output current value is determined based on the output current detection accuracy of the DC converter. For example, the second current threshold is 1A. Of the m DC converters, one or more DC converters whose output current is greater than the second current threshold set a number for one or more DC converters according to the received numbering command.

[0056] For example, the number setting command carries the serial number of the DC / DC circuit whose input terminals are currently short-circuited, i.e., the serial number of DC / DC circuit 2001. Of the m DC converters, one or more DC converters whose output current is greater than the second current threshold, i.e., one or more DC converters whose output current is within the short-circuit current range are 、1 Number of DC converters to the serial number of DC / DC circuit 2001 Set the number to indicate that one or more DC converters are connected to the DC / DC circuit 2001.

[0057] For example, the number setting command carries the string number of the photovoltaic string connected to the input terminal of a DC / DC circuit whose input terminal is currently short-circuited (i.e., the string number of photovoltaic string 11). One or more DC converters with an output current greater than the second current threshold are numbered in the format "string number of photovoltaic string 11". This number indicates that the DC converter with an output current greater than the second current threshold is connected to the DC / DC circuit 2001 and is located in the photovoltaic string 11 connected to the DC / DC circuit 2001.

[0058] Here, each DC converter is in a first operating state, and for specific implementation details regarding the setting of the DC converter number based on the serial number of the target DC / DC circuit, please refer to the description of the corresponding part in the above embodiment. Details will not be explained again here.

[0059] In yet another optional embodiment, the output operating parameters include an output voltage and an output current.

[0060] Specifically, after the power supply system 1 is powered on, the inverter 20 and all DC converters are in an initial state. Next, the inverter 20 sends a first operation command to each DC converter, and each DC converter controls itself to enter a first operating state according to the first operation command it received. After all DC converters have entered the first operating state, that is, after a first predetermined period from the time the inverter 20 sent the first operation command to the DC converters, the inverter 20 controls a short circuit between the positive and negative input terminals of one of the n DC / DC circuits, DC / DC circuit 2001, and after controlling the short circuit between the positive and negative input terminals of DC / DC circuit 2001, it sends a broadcast instruction, i.e., a number setting command, to the DC converters. When each DC converter receives a number setting command, if the DC converter determines that the input terminal of one of the n DC / DC circuits is short-circuited, the DC converter detects whether the output voltage of the DC converter is less than a third voltage threshold and whether the output current of the DC converter is greater than a second current threshold. Of the m DC converters, one or more DC converters whose output voltage is less than the third voltage threshold and whose output current is greater than the second current threshold set the number of one or more DC converters according to the received number setting command.

[0061] For example, the number setting command carries the serial number of the DC / DC circuit whose input terminals are currently short-circuited, i.e., the serial number of DC / DC circuit 2001. Of the m DC converters, one or more DC converters whose output voltage is less than the third voltage threshold and whose output current is greater than the second current threshold, i.e., one or more DC converters whose output voltage and output current are within the short-circuit voltage range and short-circuit current range, respectively. 、1 Number of DC converters to the serial number of DC / DC circuit 2001 Set the number to indicate that one or more DC converters are connected to the DC / DC circuit 2001.

[0062] For example, the number setting command carries the string number of the photovoltaic string connected to the input terminal of a DC / DC circuit whose input terminal is currently short-circuited (i.e., the string number of photovoltaic string 11). One or more DC converters whose output voltage is less than a third voltage threshold and whose output current is greater than a second current threshold are numbered in the format "string number of photovoltaic string 11". This number indicates that the DC converter whose output voltage is less than a third voltage threshold and whose output current is greater than a second current threshold is connected to the DC / DC circuit 2001 and is located in the photovoltaic string 11 connected to the DC / DC circuit 2001.

[0063] Here, each DC converter is in a first operating state, and for specific implementation details regarding the setting of the DC converter number based on the serial number of the target DC / DC circuit, please refer to the description of the corresponding part in the above embodiment. Details will not be explained again here.

[0064] Next, after the DC converters connected to the input terminals of the DC / DC circuit 2001 have completed numbering, that is, after a second pre-set duration starting from the time the inverter 20 sends a string numbering command to each DC converter, the inverter 20 further controls the input terminals of the DC / DC circuit 2001 to exit the short-circuit state, for example, by controlling a controllable switch connected between the positive and negative input terminals of the DC / DC circuit 2001 to be turned off. After the input terminals of the DC / DC circuit 2001 have exited the short-circuit state, the inverter 20 further determines whether a number has been set for any of the DC converters connected to the aforementioned n DC / DC circuits, that is, whether the DC / DC circuit 2001 is the last DC / DC circuit among the aforementioned n DC / DC circuits in a pre-set order, where the pre-set order is the order in which the inverter 20 controls the input terminals of the n DC / DC circuits to be short-circuited sequentially. If a DC converter connected to one of the aforementioned n DC / DC circuits is not assigned a number, that is, if DC / DC circuit 2001 is not the last DC / DC circuit among the aforementioned n DC / DC circuits in a predetermined order, the inverter 20 controls the input terminal of one of the DC / DC circuits connected to the DC converter that does not have a assigned number to be short-circuited, that is, the input terminal of the next DC / DC circuit following DC / DC circuit 2001 in a predetermined order to be short-circuited. Otherwise, the inverter 20 no longer performs any operations related to assigning a number to a DC converter. If the input terminal of any of the DC / DC circuits connected to a DC converter that does not have a assigned number is short-circuited, each DC converter detects whether the output operating parameters of the DC converter meet a predetermined parameter range, and if the output operating parameters of the DC converter meet a predetermined parameter range, a number is assigned to that DC converter.

[0065] After all DC converters in the power supply system 1 have completed numbering, the inverter 20 further determines the number of DC converters connected to the input terminal of each DC / DC circuit based on the respective numbers returned by the DC converters after numbering is complete; if the number of DC converters connected to the input terminal of each DC / DC circuit is greater than a quantity threshold, the inverter 20 can control the output voltage of the DC converters connected to the input terminal of the DC / DC circuit so that it is less than a fourth voltage threshold. Otherwise, the inverter 20 controls the output voltage of the DC converters connected to the input terminal of each DC / DC circuit so that it is less than a fifth voltage threshold. The fourth voltage threshold is less than the fifth voltage threshold, where the fourth voltage threshold is the maximum input voltage value of the inverter 20 and the fifth voltage threshold is the maximum output voltage value of the DC converters (e.g., 80V). For example, if the inverter 20 is a single-phase input inverter, the fourth voltage threshold is 600V; if the inverter 20 is a three-phase input inverter, the fourth voltage threshold is 1000V. To facilitate the explanation, DC / DC circuit 2001 is used below as a concrete example. Specifically, if the number of DC converters connected to the input terminal of DC / DC circuit 2001 is greater than the quantity threshold, it indicates that the photovoltaic string in which the DC converters connected to the input terminal of DC / DC circuit 2001 are located is a long string. In this case, inverter 20 controls the output voltage of the DC converters connected to the input terminal of DC / DC circuit 2001 to be less than the fourth voltage threshold, ensuring that the output voltage of the long string does not exceed the maximum input voltage value of inverter 20, thereby improving the stability of inverter 20. If the number of DC converters connected to the input terminal of DC / DC circuit 2001 is less than or equal to the quantity threshold, it indicates that the photovoltaic string in which the DC converters connected to the input terminal of DC / DC circuit 2001 are located is a short string. In this case, inverter 20 controls the output voltage of the DC converters connected to the input terminal of DC / DC circuit 2001 to be less than the fifth voltage threshold. Since the fifth voltage threshold is greater than the fourth voltage threshold, it can be seen that the voltage limit of the DC converters in the short string is higher than the voltage limit of the DC converters in the long string. This ensures high operating efficiency of the DC converters in short strings. Based on this, after all DC converters in the power supply system 1 have completed numbering, the inverter 20 can set the output voltage of all DC converters in long strings below a fourth voltage threshold and the output voltage of all DC converters in short strings below a fifth voltage threshold.

[0066] Optionally, after the DC converters connected to the input terminals of the DC / DC circuit 2001 have completed their quantity setting, the inverter 20 controls the input terminals of the DC / DC circuit 2001 to exit the short-circuit state, and after the input terminals of the DC / DC circuit 2001 have exited the short-circuit state, the inverter 20 determines the quantity of DC converters connected to the input terminals of the DC / DC circuit 2001 based on the numbers returned by the DC converters after the number setting is complete. For example, the inverter 20 collects statistics on the quantity of DC converters whose numbers match the serial number of the DC / DC circuit 2001 and obtains the quantity of DC converters connected to the input terminals of the DC / DC circuit 2001. Then, if the quantity of DC converters connected to the input terminals of the DC / DC circuit 2001 is greater than a quantity threshold, it indicates that the photovoltaic string where the DC converters connected to the DC / DC circuit 2001 are located is a long string. In this case, the inverter 20 controls the output voltage of the DC converters connected to the input terminals of the DC / DC circuit 2001 to be less than a fourth voltage threshold. Otherwise, it indicates that the solar power string where the DC converter connected to DC / DC circuit 2001 is located is a short string. In this case, inverter 20 controls the output voltage of the DC converter connected to the input terminal of DC / DC circuit 2001 to be less than the fifth voltage threshold. Next, inverter 20 determines whether a number has been assigned to a DC converter connected to one of the n DC / DC circuits, and if a number has not been assigned to a DC converter connected to one of the n DC / DC circuits, it controls the input terminal of one of the DC / DC circuits connected to the DC converter that does not have a assigned number to be short-circuited. The above steps are repeated.The numbers continue to be set for DC converters that do not have a set number; the output voltage of a DC converter that has just been set is controlled based on the length of the photovoltaic string in which the DC converter is located, until the output voltage of the DC converters in all long strings falls below the fourth voltage threshold and the output voltage of the DC converters in all short strings falls below the fifth voltage threshold, i.e., until the inverter 20 has finished setting the output voltage limits for all DC converters in the power supply system 1.

[0067] Furthermore, when high-temperature derating occurs, the inverter 20 can control the output voltage of the DC converters in the long string to be below a sixth voltage threshold, which is below the fourth voltage threshold; and it can also control the output voltage of the DC converters in the short string to remain below a fifth voltage threshold, i.e., it can control the inverter 20 to decrease the output voltage limit of the long string while keeping the output voltage limit of the short string unchanged, thereby reducing the input voltage of the inverter 20 and reducing the losses of the inverter 20.

[0068] It will be understood that the inverter 20 can control the input terminal of one DC / DC circuit to be short-circuited, and then simultaneously assign numbers to all DC converters connected to the DC / DC circuit whose input terminals are short-circuited. That is, in the power supply system 1 provided in this application, numbers are assigned to the DC converters based on the DC / DC circuit in the inverter. Compared to assigning numbers to each DC converter individually, the method of the power supply system 1 provided in this application can effectively reduce the duration required to assign numbers to all DC converters.

[0069] It should be noted that the power supply system 1 shown in Figure 3 is explained using an example where there is a one-to-one correspondence between the DC converter and the photovoltaic modules. The power supply system 1 provided in this application is also applicable when there is a one-to-many correspondence between the DC converter and the photovoltaic modules. When there is a one-to-many correspondence between the DC converter and the photovoltaic modules, that is, when one DC converter corresponds to multiple photovoltaic modules, the connection relationship between the DC converter and the multiple photovoltaic modules is such that the output terminals of the multiple photovoltaic modules are connected in series and / or parallel, and then connected to the input terminals of the DC converter. Furthermore, the correspondence between all DC converters and photovoltaic modules may be the same or different. In other words, the number of photovoltaic modules connected to the input terminals of all DC converters may be the same or different. If two DC converters each have a one-to-many correspondence with photovoltaic modules, the two DC converters may be connected to the photovoltaic modules in the same or different ways. For example, suppose the first DC converter corresponds to two photovoltaic modules and the second DC converter corresponds to three photovoltaic modules. In this case, the output terminals of the two photovoltaic modules corresponding to the first DC converter may be connected in series and then connected to the input terminals of the first DC converter, while the output terminals of the three photovoltaic modules corresponding to the second DC converter may all be connected in parallel to the input terminals of the second DC converter.

[0070] In this embodiment of the present application, the inverter 20 may be controlled to short-circuit the input terminal of one DC / DC circuit, and then a number may be simultaneously assigned to all DC converters connected to the short-circuited DC / DC circuit. That is, in the power supply system 1 provided in the present application, a number is assigned to the DC converters based on the DC / DC circuit in the inverter. Compared to the method of numbering DC converters one by one, the method relating to the power supply system 1 provided in the present application can effectively reduce the time required to number all DC converters. Furthermore, in the prior art method of numbering DC converters one by one, DC converters are numbered primarily based on whether the inverter's input terminal sampling voltage is within the voltage value output range. In this method, it is not possible to determine whether the input terminal sampling voltage was output by a DC converter, and if the inverter's input terminal is directly connected to a photovoltaic module, the inverter still obtains an input terminal sampling voltage that fits within the voltage value output range through sampling, even if all DC converters are powered off. However, in this application, each DC converter uses a method to determine whether the output operating parameters of the DC converter fit within a pre-set parameter range, thereby preventing the incorrect numbering of the DC converter due to the inverter's input terminal being directly connected to the photovoltaic module. This improves the accuracy of setting the string number by the DC converter.

[0071] To facilitate understanding, the operating principle of the power supply system 1 will be explained below by referring to the control sequence diagram of the DC converter shown in Figure 4 and using an example in the power supply system 1 shown in Figure 3 where the first preset voltage value is 20V, the third voltage threshold is 4V, and n=2.

[0072] Figure 4 is a control sequence diagram of the DC converter according to the present application. As shown in Figure 4, during the time period from t0 to t1, all DC converters and inverters 20 in the power supply system 1 are in their initial state. Specifically, the inverters 20 are in standby mode, all DC converters are powered off, the output voltage of each solar power generation string is 0V, and the string number of all DC converters is 0.

[0073] At time t1, the inverter 20 sends a startup voltage adjustment command to each DC converter, and all DC converters are started up according to the received startup voltage adjustment command, and their respective output voltages are controlled to 20V. Since the control sequence diagrams for DC converters connected to the same DC / DC circuit are the same, for the sake of clarity, in Figure 4, the control sequence diagram for DC converters connected to the input terminals of a DC / DC circuit is explained using the example where the DC converter connected to the input terminal of DC / DC circuit 2001 is DC converter 111, and the DC converter connected to the input terminal of DC / DC circuit 200n is DC converter 1n1.

[0074] During the time period from t1 to t2, the output voltage Uo111 of DC converter 111 and the output voltage Uo1n1 of DC converter 1n1 both remain at 20V, and the output current Io111 of DC converter 111 and the output current Io1n1 of DC converter 1n1 are approximately 0A.

[0075] At time t2, the inverter 20 sends a current adjustment command to each DC converter, and the current adjustment command is 3A. All DC converters control their respective output currents according to the received current adjustment command. As shown in Figure 4, at time t2, the output current Io111 of DC converter 111 and the output current Io1n1 of DC converter 1n1 are approximately 0A.

[0076] During the time period from t2 to t3, the output voltage Uo111 of DC converter 111 and the output voltage Uo1n1 of DC converter 1n1 both remain at 20V, and the output current Io111 of DC converter 111 and the output current Io1n1 of DC converter 1n1 are approximately 0A.

[0077] At time t3, the inverter 20 is controlled so that the input terminal of the DC / DC circuit 2001 is short-circuited. The output voltage Uo111 and output current Io111 of the DC converter 111 are 0V and 3A, respectively, and the output voltage Uo1n1 and output current of the DC converter 1n1 are 0V and 3A. I o1n1 are 20V and 0A, respectively.

[0078] During the time period from t3 to t4, the output voltage Uo111 and output current Io111 of the DC converter 111 remain at 0V and 3A, respectively, while the output voltage Uo1n1 and output current of the DC converter 1n1 remain at 0V and 3A. I o1n1 remains at 20V and 0A, respectively.

[0079] At time t4, inverter 20 sends a number setting command to each DC converter, which carries the serial number of DC / DC circuit 2001. After receiving the number setting command, each DC converter determines whether its output voltage is less than 4V and / or whether its output current is greater than 1A; if the output voltage of the DC converter is less than 4V and / or the output current of the DC converter is greater than 1A, it sets the number of the DC converter based on the serial number of DC / DC circuit 2001. As shown in Figure 4, the output voltage of DC converter 111 is 0V, which is less than 4V, and the output current of DC converter 111 is 3A, which is greater than 1A. In this case, DC converter 111 sets its number based on the serial number of DC / DC circuit 2001. The output voltage of DC converter 1n1 is 20V, which is greater than 4V, and the output current of DC converter 1n1 is 0A, which is less than 1A. In this case, the DC converter 1n1 does not set a number.

[0080] During the time period from t4 to t5, the output voltage Uo111 and output current Io111 of the DC converter 111 remain at 0V and 3A, respectively, while the output voltage Uo1n1 and output current of the DC converter 1n1 remain at 0V and 3A. I o1n1 remains at 20V and 0V, respectively.

[0081] At time t5, the inverter 20 controls the input terminal of the DC / DC circuit 2001 to escape the short-circuit state, and the output voltage Uo111 and output current Io111 of the DC converter 111 are restored to 20V and 0V, respectively.

[0082] During the time period from t5 to t6, the output voltage Uo111 and output current Io111 of DC converter 111 are 20V and 0A, respectively, and the output voltage Uo1n1 and output current of DC converter 1n1 are 20V and 0A. I o1n1 are 20V and 0A, respectively.

[0083] At time t6, the inverter 20 is controlled so that the input terminal of the DC / DC circuit 200n is short-circuited. The output voltage Uo111 and output current Io111 of the DC converter 111 are 20V and 0A, respectively, and the output voltage Uo1n1 and output current of the DC converter 1n1 are 20V and 0A. I o1n1 are 0V and 3A, respectively.

[0084] [ During the time period from t6 to t7, the output voltage Uo111 and output current Io111 of the DC converter 111 remain at 20V and 0V, respectively, while the output voltage Uo1n1 and output current of the DC converter 1n1 remain at 20V and 0V, respectively. I o1n1 remains at 0V and 3A, respectively.

[0085] At time t7, inverter 20 sends a number setting command to each DC converter, which carries the serial number of DC / DC circuit 200n. After receiving the number setting command, each DC converter determines whether its output voltage is less than 4V and / or whether its output current is greater than 1A; if the output voltage of the DC converter is less than 4V and / or the output current of the DC converter is greater than 1A, it sets the number of the DC converter based on the serial number of DC / DC circuit 200n. As shown in Figure 4, the output voltage of DC converter 1n1 is 0V, which is less than 4V, and the output current of DC converter 1n1 is 3A, which is greater than 1A. In this case, DC converter 1n1 sets its number based on the serial number of DC / DC circuit 200n. The output voltage of DC converter 111 is 20V, which is greater than 4V, and the output current of DC converter 111 is 0A, which is less than 1A. In this case, the DC converter 111 does not set a number.

[0086] During the time period from t7 to t8, the output voltage Uo111 and output current Io111 of DC converter 111 remain at 20V and 0A, respectively, while the output voltage Uo1n1 and output current of DC converter 1n1 remain at 20V and 0A. I o1n1 remains at 0V and 3A, respectively.

[0087] At time t8, the inverter 20 controls the input terminal of the DC / DC circuit 200n to escape the short-circuit state, and the output voltage Uo111 and output current Io111 of the DC converter 1n1 are restored to 20V and 0V, respectively.

[0088] Figure 5 is a schematic flowchart of the control method for a power supply system according to the present application. The control method for a power supply system provided in this embodiment of the present application is applicable to the power supply system 1 shown in Figure 3. The control method for a power supply system may include the following steps:

[0089] S101: Control the input terminal of one of the DC / DC circuits in at least two DC / DC circuits to be short-circuited.

[0090] In an optional implementation, the inverter controls a short circuit between the positive and negative input terminals of at least two DC / DC circuits.

[0091] In another optional implementation, after each DC converter enters a first operating state, the inverter controls a short circuit between the positive and negative input terminals of at least two DC / DC circuits.

[0092] S102: Determine whether the output operating parameters of at least four DC converters fit within a predetermined parameter range.

[0093] In practice, if the input terminals of at least two DC / DC circuits are short-circuited, at least four DC converters determine whether their respective output operating parameters meet a preset operating parameter range.

[0094] Specifically, the inverter controls the input terminal of one of the DC / DC circuits in at least two DC / DC circuits to be short-circuited, and then sends a broadcast instruction to at least four DC converters. Upon receiving the broadcast instruction, the at least four DC converters determine that the input terminal of one of the DC / DC circuits in at least two DC / DC circuits is short-circuited. In this case, the at least four DC converters determine whether their respective output operating parameters fit within a predetermined parameter range.

[0095] In an optional embodiment, the output operating parameters include the output voltage.

[0096] Upon receiving a broadcast instruction, at least four DC converters determine that the input terminal of one DC / DC circuit in at least two DC / DC circuits is short-circuited. In this case, at least four DC converters determine whether the output voltages of at least four DC converters are below a third voltage threshold, and if the output voltages of at least four DC converters are below the third voltage threshold threshold If the value is less than the specified value, it is determined that at least four DC converter output operating parameters are within the pre-set parameter range.

[0097] In another optional embodiment, the output operating parameters include the output current.

[0098] Upon receiving a broadcast instruction, at least four DC converters determine that the input terminal of one DC / DC circuit in at least two DC / DC circuits is short-circuited. In this case, at least four DC converters determine whether the output current of at least four DC converters is greater than a second current threshold, and if the output current of at least four DC converters is greater than the second current threshold, they determine that the respective output operating parameters are within a pre-set parameter range.

[0099] In yet another optional implementation, the output operating parameters include the output voltage and output current.

[0100] Upon receiving a broadcast instruction, at least four DC converters determine that the input terminal of one DC / DC circuit in at least two DC / DC circuits is short-circuited. In this case, at least four DC converters determine whether the output voltages of at least four DC converters are less than a third voltage threshold and whether the output currents of at least four DC converters are greater than a second current threshold. If the output voltages of at least four DC converters are less than the third voltage threshold and the output currents of at least four DC converters are greater than the second current threshold, then it is determined that the respective output operating parameters are within a pre-set parameter range.

[0101] Each DC converter performs step S103 if the output operating parameters of the DC converter fit within a preset parameter range. Otherwise, each DC converter performs step S104.

[0102] S103: In at least four DC converters, assign a number to one or more DC converters whose output operating parameters fit within a predetermined parameter range.

[0103] The numbers indicate that one or more DC converters are connected to a DC / DC circuit whose input terminals are currently short-circuited.

[0104] In the optional implementation, the broadcast instruction includes the serial number of the DC / DC circuit whose input terminals are currently shorted.

[0105] At least four DC converters are numbered based on the serial number of the DC / DC circuit whose input terminals are currently shorted, for one or more DC converters whose output operating parameters fit within a predetermined parameter range.

[0106] In an alternative implementation, the broadcast instruction includes the string number of the solar power string connected to the input terminal of a DC / DC circuit whose input terminal is currently shorted.

[0107] At least four DC converters are numbered based on the string number of the photovoltaic string connected to the input terminal of a DC / DC circuit whose input terminal is currently shorted, for at least four DC converters whose output operating parameters fit within a predetermined parameter range.

[0108] S104: Do not set a number for the DC converter.

[0109] For more operations performed by the inverter and each DC converter in the control method for a power supply system provided in this application in a particular implementation, please refer to the implementation configuration performed by the inverter 20 and each DC converter shown in Figure 3. Details are again not described here. It should be noted that this embodiment is described by using an example in which the inverter 20 and each DC converter directly perform the control method for the power supply system 1. Alternatively, the control method for the power supply system 1 provided in this application may be performed by a system controller within the power supply system 1 and indirectly by the system controller controlling the inverter and each DC converter. This is not limited in this application.

[0110] In this embodiment of the present application, the inverter controls the input terminal of one DC / DC circuit to be short-circuited, and then simultaneously assigns numbers to all DC converters connected to the DC / DC circuit whose input terminals are short-circuited. That is, in the power supply system provided in the present application, the DC converters are assigned numbers based on the DC / DC circuit in the inverter. Compared to assigning numbers to each DC converter individually, the control method for the power supply system provided in the present application can effectively reduce the time required to assign numbers to all DC converters.

[0111] Figures 6A and 6B are schematic flowcharts of the control method for a power supply system according to the present application. The control method for a power supply system provided in this embodiment of the present application is applicable to power supply system 1 shown in Figure 3. The control method for a power supply system may include the following steps:

[0112] S201: Control the input terminal of one DC / DC circuit in at least two DC / DC circuits to be short-circuited.

[0113] S202: Determine whether the output operating parameters of at least four DC converters fit within a predetermined parameter range.

[0114] Each DC converter performs step S203 if the output operating parameters of the DC converter fit within a preset parameter range. Otherwise, each DC converter performs step S204.

[0115] S203: In at least four DC converters, assign a number to one or more DC converters whose output operating parameters fit within a predetermined parameter range.

[0116] After setting the number of the DC converter, DC converters whose output operating parameters fit within the pre-set parameter range (i.e., DC converters connected to a DC / DC circuit whose input terminals are currently shorted) perform step S205.

[0117] S204: Do not set a number for the DC converter.

[0118] For specific implementations of steps S201 to S204, please refer to the description of steps S101 to S104 in the embodiment of the method shown in Figure 5. Further details will not be explained here.

[0119] S205: After the number setting is complete, a DC converter connected to a DC / DC circuit whose input terminal is currently shorted controls the input terminal of the DC / DC circuit, which is currently shorted, to exit the short-circuit state.

[0120] Specifically, after the numbering is complete, the inverter controls the input terminals of the DC / DC circuit, which are currently short-circuited, to exit the short-circuit state. Then, step S206 is performed.

[0121] S206: Determine whether at least two DC / DC circuits include a DC / DC circuit connected to a DC converter that does not have a setting number.

[0122] In the implementation, the inverter sequentially determines, based on the number returned by the DC converter having a setting number, whether the serial number of the DC / DC circuit appears in the number of the DC converter having a setting number. If the serial numbers of at least two DC / DC circuits appear in the number of the DC converter having a setting number, it indicates that the numbers of all DC converters connected to at least two DC / DC circuits are set, and the inverter performs step S208. If there is a DC / DC circuit among at least two whose serial number does not appear in the number of the DC converter with a setting number, it indicates that there is a DC / DC circuit among at least two DC / DC circuits connected to a DC converter that does not have a setting number, and step S207 is performed.

[0123] For example, suppose a power supply system has a total of five DC converters, and the inverter has a total of two DC / DC circuits: a first DC / DC circuit and a second DC / DC circuit. If the total number of current DC converters with setting numbers is two, and the serial number of the first DC / DC circuit appears in the numbers of the two DC converters with setting numbers, it indicates that numbers have been assigned to all DC converters connected to the first DC / DC circuit, and that no numbers have been assigned to the DC converters connected to the second DC / DC circuit, and the inverter performs step S207. If the total number of current DC converters with setting numbers is five, and the serial number of the first DC / DC circuit appears in the numbers of the two DC converters with setting numbers, and the serial number of the second DC / DC circuit appears in the numbers of the other three DC converters with setting numbers, it indicates that numbers have been assigned to all DC converters connected to the first and second DC / DC circuits, and the inverter performs step S208.

[0124] In another implementation, the inverter determines whether there are at least two DC / DC circuits connected to a DC converter that does not have a set number, based on whether the serial number of the DC / DC circuit that is currently out of short-circuit condition is the serial number of the last DC / DC circuit in a pre-set sequence. Specifically, if the serial number of the DC / DC circuit that is currently out of short-circuit condition is not the serial number of the last DC / DC circuit in a pre-set sequence, the inverter executes step S207. Otherwise, step S208 is executed.

[0125] S207: DC / DC converter connected to a DC converter without a setting number Road The input terminal is controlled to be short-circuited.

[0126] In the implementation, the inverter determines the DC / DC circuit connected to a DC converter without a setting number based on the number returned by the DC converter with a setting number, and the inverter then determines the DC / DC circuit connected to the DC converter without a setting number. Road The input terminals are controlled to be short-circuited.

[0127] In another implementation, when the inverter determines a DC / DC circuit connected to a DC converter that does not have a set number based on whether the serial number of the DC / DC circuit that is currently out of short-circuit condition is the serial number of the last DC / DC circuit in a pre-set sequence, the inverter controls the input terminal of the next DC / DC circuit after the DC / DC circuit that is currently out of short-circuit condition in the pre-set sequence to be short-circuited.

[0128] S208: The system no longer controls the input terminals of any DC / DC circuit to be short-circuited, and at least one of the two DC / DC circuits is designated as the target DC / DC circuit.

[0129] The inverter no longer controls the input terminals of any DC / DC circuit to be short-circuited, but instead determines one of at least two DC / DC circuits as the target DC / DC circuit.

[0130] S209: Determine whether the quantity of DC converters connected to the input terminal of the target DC / DC circuit is greater than the quantity threshold.

[0131] In the implementation, the inverter collects statistics on the number of DC converters among all DC converters that have the same serial number as the target DC / DC circuit to obtain the number of DC converters connected to the input terminal of the target DC / DC circuit. If the number of DC converters connected to the input terminal of the target DC / DC circuit is greater than a quantity threshold, it indicates that the photovoltaic string in which the DC converters connected to the target DC / DC circuit are located is a long string, and the inverter performs step S210. Otherwise, it indicates that the photovoltaic string in which the DC converters connected to the target DC / DC circuit are located is a short string, and step S211 is performed.

[0132] S210: Control the output voltage of the DC converter connected to the input terminal of the target DC / DC circuit so that it falls below a fourth voltage threshold.

[0133] The inverter sets the output voltage limit for the DC converter connected to the target DC / DC circuit by controlling the output voltage of the DC converter connected to the input terminal of the target DC / DC circuit so that it is below a fourth voltage threshold. Thus, the output voltages of all DC converters in the long string connected to the inverter may be below the fourth voltage threshold, ensuring that the output voltage of the long string does not exceed the maximum input voltage of the inverter, thereby improving the stability of the inverter. The inverter then performs step S212.

[0134] S211: Control the output voltage of the DC converter connected to the input terminal of the target DC / DC circuit so that it falls below a fifth voltage threshold.

[0135] The inverter controls the output voltage of the DC converter connected to the input terminal of the target DC / DC circuit so that it is below a fifth voltage threshold, thereby setting the output voltage limit for the DC converter connected to the target DC / DC circuit, where the fifth voltage threshold is greater than the fourth voltage threshold. Therefore, the output voltages of all DC converters in the short string connected to the inverter are below the fifth voltage threshold. Since the fifth voltage threshold is greater than the fourth voltage threshold, it can be seen that the voltage limit for the DC converters in the short string is higher than the voltage limit for the DC converters in the long string. This ensures high operating efficiency for the DC converters in the short string. Next, the inverter performs step S212.

[0136] S212: Determine whether, among at least two DC / DC circuits, there is a DC / DC circuit connected to a DC converter that does not have a set output voltage limit.

[0137] The inverter determines whether at least two DC / DC circuits are connected to a DC converter that does not have a set output voltage limit. If at least two DC / DC circuits are connected to a DC converter that does not have a set output voltage limit, step S213 is executed. Otherwise, step S214 is executed.

[0138] S213: DC / DC converter connected to a DC converter that does not have a set output voltage limit. Road This is then determined to be the target DC / DC circuit.

[0139] DC / DC converter connected to a DC converter without a set output voltage limit Road After determining the target DC / DC circuit, the inverter performs step S209.

[0140] S214: No longer set an output voltage limit for any DC converter connected to the input terminal of any DC / DC circuit.

[0141] If, among at least two DC / DC circuits, there is no DC / DC circuit connected to a DC converter that does not have a set output voltage limit, it indicates that the output voltages of all long-string DC converters are below the fourth voltage threshold, and the output voltages of all short-string DC converters are below the fifth voltage threshold, and the inverter no longer sets an output voltage limit for any DC converter connected to any DC / DC circuit.

[0142] Next, after the inverter has finished setting the output voltage limits for all DC converters, if a high-temperature drop occurs, the inverter can reduce the inverter's input voltage and thereby reduce the inverter's losses by controlling the output voltage of the DC converters in the long string to be below the sixth voltage threshold (the sixth voltage threshold is below the fourth voltage threshold); and controlling the output voltage of the DC converters in the short string to remain below the fifth voltage threshold, that is, by controlling the output voltage limits of the long string to decrease and the output voltage limits of the short string to remain unchanged.

[0143] For further operations performed by the inverter and each DC converter in the control method for a power supply system provided in this application in a particular implementation, please refer to the implementation configuration performed by the inverter 20 and each DC converter shown in Figure 3. Details are again not described here. This embodiment is explained by using an example in which the inverter 20 and each DC converter directly perform the control method for the power supply system 1. Alternatively, the control method for the power supply system 1 provided in this application may be performed by a system controller in the power supply system 1, and indirectly by the system controller controlling the inverter and each DC converter. This is not limited in this application.

[0144] In this embodiment of the present application, after the inverter controls the input terminal of one DC / DC circuit to be short-circuited, it is possible to simultaneously assign numbers to all DC converters connected to the DC / DC circuit whose input terminals are short-circuited. That is, in the power supply system provided in the present application, the DC converters are assigned numbers based on the DC / DC circuit in the inverter. Compared to assigning numbers to DC converters one by one, the control method for the power supply system provided in the present application can effectively reduce the time required to assign numbers to all DC converters.

[0145] The foregoing description is merely a specific implementation of the present application and is not intended to limit the scope of protection of the present application. Any modification or substitution that is readily conceivable by a person skilled in the art within the scope of the technical scope disclosed in the present application shall fall within the scope of protection of the present application. Accordingly, the scope of protection of the present application shall be subject to the scope of protection of the claims.

Claims

1. A power supply system comprising an inverter and at least four DC converters, The inverter includes at least two DC / DC circuits, the input terminal of each of the at least two DC / DC circuits being connected to the output terminals of at least two DC converters in the at least four DC converters, the output terminals of the at least two DC converters being connected in series, and the input terminal of each of the at least four DC converters being connected to the photovoltaic module corresponding to the DC converter; The inverter is configured to control the short-circuiting of the input terminal of one of the at least two DC / DC circuits; and A power supply system comprising: at least four DC converters: detecting whether the output operating parameters of the at least four DC converters conform to a preset parameter range in response to the input terminal of one DC / DC circuit in the at least two DC / DC circuits being short-circuited; and setting a number for one or more DC converters whose output operating parameters conform to the preset parameter range of the at least four DC converters, wherein the number indicates that the one or more DC converters are connected to the one DC / DC circuit.

2. In the power supply system according to claim 1, the inverter is further configured to transmit a broadcast instruction to the at least four DC converters after controlling the input terminal of one of the at least two DC / DC circuits to be short-circuited; Responding to a short-circuit at the input terminal of one of the at least two DC / DC circuits includes: the at least four DC converters responding to the reception of the broadcast instruction; and A power supply system comprising at least four DC converters, configured to set a number for one or more DC converters whose output operating parameters conform to a pre-set parameter range of the at least four DC converters, in accordance with a received broadcast instruction.

3. In the power supply system according to claim 2, the broadcast instruction includes the serial number of a DC / DC circuit whose input terminal is currently short-circuited; and A power supply system comprising at least four DC converters, configured to assign a number to one or more DC converters whose output operating parameters conform to a pre-set parameter range of the at least four DC converters, based on the serial number of a DC / DC circuit whose input terminals are currently short-circuited.

4. In the power supply system according to claim 2, the at least two DC converters and the photovoltaic modules corresponding to the at least two DC converters form a photovoltaic string, and the broadcast instruction includes the string number of the photovoltaic string connected to the input terminal of a DC / DC circuit whose input terminal is currently short-circuited; and A power supply system comprising at least four DC converters, configured to assign a number to one or more DC converters whose output operating parameters conform to a pre-set parameter range of the at least four DC converters, based on the string number of a photovoltaic string connected to the input terminal of a DC / DC circuit whose input terminal is currently short-circuited.

5. A power supply system according to any one of claims 1 to 4, wherein the inverter is configured to sequentially control the input terminal of one of the at least two DC / DC circuits so that the short-circuit condition is removed after the input terminal is short-circuited, until all of the at least four DC converters have completed numbering.

6. In the power supply system according to claim 5, sequentially controlling the input terminal of one DC / DC circuit in the at least two DC / DC circuits so that the short-circuit condition is removed after the input terminal is short-circuited, until all at least four DC converters have completed numbering: A power supply system comprising controlling the input terminal of one of the at least two DC / DC circuits connected to a DC converter that does not have a setting number to be short-circuited, and controlling the input terminal of any of the at least two DC / DC circuits connected to a DC converter that has a setting number to be released from the short-circuited state after the DC converter that does not have a setting number has set a number based on the serial number of the DC / DC circuit whose input terminal is currently short-circuited.

7. In the power supply system according to any one of claims 1 to 6, the at least four DC converters are: A power supply system further configured to control the output voltages of at least four DC converters to a first preset voltage value before responding to a short circuit at the input terminal of one of the at least two DC / DC circuits, wherein the first preset voltage value is greater than or equal to a first voltage threshold and less than a second voltage threshold, the first voltage threshold being the minimum detectable output voltage value of the DC converter and the second voltage threshold being the maximum output voltage value of the DC converter.

8. In the power supply system according to any one of claims 1 to 6, the at least four DC converters are: A power supply system further configured to control the output currents of at least four DC converters to a first preset current value before responding to a short circuit at the input terminal of one of the at least two DC / DC circuits, wherein the first preset current value is less than or equal to a first current threshold, and the first current threshold is the maximum output current value of the DC converter.

9. In the power supply system according to any one of claims 1 to 6, the at least four DC converters are: A power supply system further configured to control the output voltage and output current of at least four DC converters to a first preset voltage value and a first preset current value, respectively, before responding to a short circuit at the input terminal of one of the at least two DC / DC circuits, wherein the first preset voltage value is greater than or equal to a first voltage threshold and less than a second voltage threshold, the first preset current value is less than or equal to a first current threshold, the first voltage threshold is the minimum detectable output voltage value of the DC converter, the second voltage threshold is the maximum output voltage value of the DC converter, and the first current threshold is the maximum output current value of the DC converter.

10. In the power supply system according to any one of claims 1 to 9, the output operating parameter includes an output voltage or an output current; A power supply system comprising at least four DC converters configured to detect, in response to a short circuit at the input terminal of one of the at least two DC / DC circuits, whether the output voltage of the at least four DC converters is less than a third voltage threshold, or whether the output current of the at least four DC converters is greater than a second current threshold.

11. In the power supply system according to any one of claims 1 to 9, the output operating parameter includes an output voltage or an output current; A power supply system comprising at least four DC converters configured to detect, in response to a short-circuit at the input terminal of one of the at least two DC / DC circuits, whether the output voltage of the at least four DC converters is less than a third voltage threshold, and whether the output current of the at least four DC converters is greater than a second current threshold.

12. In the power supply system according to any one of claims 1 to 11, the inverter is: A DC converter connected to the input terminal of one of the at least two DC / DC circuits controls the input terminal of the one DC / DC circuit to exit the short-circuit state after the numbering is complete; and A power supply system further configured such that, after the input terminal of one DC / DC circuit has exited the short-circuit state, the output voltage of a DC converter connected to the input terminal of one DC / DC circuit is controlled to be less than a fourth voltage threshold in response to the quantity of DC converters connected to the input terminal of one DC / DC circuit being greater than a quantity threshold.

13. In the power supply system according to any one of claims 1 to 11, the inverter is: A DC converter connected to the input terminal of one of the at least two DC / DC circuits controls the input terminal of the one DC / DC circuit to exit the short-circuit state after the numbering is complete; and A power supply system further configured such that, after the input terminal of one DC / DC circuit has exited the short-circuit state, the output voltage of a DC converter connected to the input terminal of one DC / DC circuit is controlled to be less than a fifth voltage threshold in response to the quantity of DC converters connected to the input terminal of one DC / DC circuit being less than or equal to a quantity threshold.

14. A power supply system according to any one of claims 1 to 13, wherein the inverter further includes a DC bus and an inverter circuit, the output terminals of at least two DC / DC circuits connected in parallel to the DC bus, and the inverter circuit connected to the DC bus.

15. A control method for a power supply system, which is: A step of controlling the input terminal of one DC / DC circuit in at least two DC / DC circuits to be short-circuited; In response to the input terminal of one of the at least two DC / DC circuits being short-circuited, the step of detecting whether the output operating parameters of at least four DC converters conform to a predetermined parameter range; and A step of assigning a number to one or more DC converters whose output operating parameters conform to a pre-set parameter range of the at least four DC converters, wherein the number indicates that the one or more DC converters are connected to the one DC / DC circuit; The method includes, and is applicable to a power supply system, the power supply system including an inverter and the at least four DC converters, the inverter including at least two DC / DC circuits, the input terminal of each DC / DC circuit in the at least two DC circuits being connected to the output terminals of at least two DC converters in the at least four DC converters, the output terminals of the at least two DC converters being connected in series, and the input terminal of each DC converter in the at least four DC converters being connected to a photovoltaic module corresponding to the DC converter.

16. In the method according to claim 15: The steps include controlling the input terminal of one of the DC / DC circuits in at least two DC / DC circuits to be short-circuited, and then sending a broadcast instruction to the at least four DC converters; The further includes, in response to the input terminal of one DC / DC circuit in the at least two DC / DC circuits being short-circuited: the at least four DC converters responding to the reception of the broadcast instruction; and The step of setting a number for one or more DC converters whose output operating parameters fit within the pre-set parameter ranges of the at least four DC converters is: A method comprising the step of assigning a number to one or more DC converters whose output operating parameters conform to a pre-set parameter range of the at least four DC converters, in accordance with a received broadcast instruction.

17. In the method according to claim 16: The broadcast instruction includes the serial number of the DC / DC circuit whose input terminal is currently shorted; and The step of assigning a number to one or more DC converters whose output operating parameters fit within a pre-set parameter range for at least four DC converters, in accordance with a received broadcast instruction, is: A method comprising the step of assigning a number to one or more DC converters whose output operating parameters conform to a predetermined parameter range of the at least four DC converters, based on the serial number of a DC / DC circuit whose input terminals are currently shorted.

18. The method according to claim 16, wherein the at least two DC converters and the photovoltaic modules corresponding to the at least two DC converters form a photovoltaic string, and the broadcast instruction includes the string number of the photovoltaic string connected to the input terminal of a DC / DC circuit whose input terminal is currently shorted; and The step of assigning a number to one or more DC converters whose output operating parameters fit within a pre-set parameter range for at least four DC converters, in accordance with a received broadcast instruction, is: A method comprising the step of assigning a number to one or more DC converters whose output operating parameters conform to a pre-set parameter range of the at least four DC converters, based on the string number of a photovoltaic string connected to the input terminal of a DC / DC circuit whose input terminal is currently short-circuited.

19. In the method according to any one of claims 15 to 18, The steps to control the input terminal of one DC / DC circuit in at least two DC / DC circuits to be short-circuited are: A method comprising the step of sequentially controlling the input terminal of one DC / DC circuit in the at least two DC / DC circuits so that the input terminal is short-circuited and then relieved of the short-circuit condition, until all at least four DC converters have completed numbering.

20. In the method according to claim 19, The step of sequentially controlling the input terminal of one of the at least two DC / DC circuits so that the input terminal is short-circuited and then relieved of the short-circuit condition, until all at least four DC converters have completed numbering, is: A method comprising the steps of controlling the input terminal of a DC / DC circuit connected to a DC converter that has a setting number, which is one of the at least two DC / DC circuits, so that it is short-circuited, and after the DC converter that has a setting number has set a number based on the serial number of the DC / DC circuit whose input terminal is currently short-circuited, controlling the input terminal of any of the at least two DC / DC circuits connected to a DC converter that has a setting number so that it is no longer short-circuited.

21. The method according to any one of claims 15 to 20, further: A step of controlling a DC converter connected to the input terminal of one of the DC / DC circuits in the at least two DC / DC circuits so that the input terminal of the one DC / DC circuit is no longer short-circuited after the numbering is complete; and Step 1: After the input terminal of the one DC / DC circuit has exited the short-circuit state, in response to the quantity of DC converters connected to the input terminal of the one DC / DC circuit being greater than a quantity threshold, control the output voltage of the DC converter connected to the input terminal of the one DC / DC circuit so that it is less than a fourth voltage threshold; A method that includes this.

22. The method according to any one of claims 15 to 20, further: A step of controlling a DC converter connected to the input terminal of one of the DC / DC circuits in the at least two DC / DC circuits so that the input terminal of the one DC / DC circuit is no longer short-circuited after the numbering is complete; and Step 1: After the input terminal of the one DC / DC circuit has exited the short-circuit state, in response to the quantity of DC converters connected to the input terminal of the one DC / DC circuit being less than or equal to a quantity threshold, control the output voltage of the DC converter connected to the input terminal of the one DC / DC circuit so that it is less than a fifth voltage threshold; A method that includes this.

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