Inverter and control method thereof

Abstract

The invention discloses an inverter and a control method thereof, the direct current end of the inverter is connected with m DCDC units, each DCDC unit is connected with at least n photovoltaic strings, and each photovoltaic string is provided with a direct current input terminal; the control method comprises the following steps: acquiring temperature data of all direct current input terminals; numbering and grouping the temperature data of all the direct current input terminals, and obtaining the maximum value of each group of temperature data; and based on the maximum value of the temperature data of all the groups, determining whether a temperature-abnormal DC input terminal exists in all the DC input terminals and positioning the position of the temperature-abnormal DC input terminal. According to the inverter and the control method thereof provided by the invention, the required controller interface resource is small, the hardware cost is low, and meanwhile, the accurate positioning of temperature abnormity is realized.

Description

Technical Field

[0001] The present application relates to the technical field of inverters, and in particular to an inverter and a control method thereof. Background Art

[0002] Inverters, such as photovoltaic inverters and energy storage inverters, are important power conversion devices that convert direct current into alternating current. In actual applications, there are many accidents such as fire and burning of inverters due to poor crimping of terminals. By detecting the temperature of the terminals, abnormal branches can be effectively identified, so that the inverter can take effective protection actions to avoid fire failures in the inverter, greatly improving the stability and reliability of the inverter.

[0003] The existing temperature detection circuit generally detects the temperature of each terminal, and then the controller compares the terminal temperature with the preset protection threshold to identify whether the terminal is abnormal. However, the temperature detection of each terminal is sent to the controller, which not only increases the hardware detection cost, but also consumes too much controller interface resources, resulting in resource waste. Summary of the invention

[0004] The present application aims to provide an inverter and a control method thereof to solve the problems of high hardware detection cost and excessive controller interface resource consumption in existing inverters.

[0005] On one hand, the present application provides a control method for an inverter, wherein the DC end of the inverter is connected to m DCDC units, each DCDC unit is connected to at least n photovoltaic strings, and each photovoltaic string has a DC input terminal; wherein n and m are both positive integers;

[0006] The control method comprises:

[0007] Get the temperature data of all DC input terminals;

[0008] The temperature data of all DC input terminals are numbered and grouped, and the maximum value of each group of temperature data is obtained;

[0009] Based on the maximum value of the temperature data of all the groups, it is determined whether there is a DC input terminal with abnormal temperature among all the DC input terminals and the position of the DC input terminal with abnormal temperature is located.

[0010] On the other hand, the present application provides an inverter, wherein the DC end of the inverter is connected to m DCDC units, each DCDC unit is connected to at least n photovoltaic strings, and each photovoltaic string has a DC input terminal; wherein n and m are both positive integers;

[0011] The inverter further includes a control unit configured to execute the aforementioned control method.

[0012] The inverter and control method thereof provided by the present application number and group the temperature data of all DC input terminals and obtain the maximum value of each group of temperature data; based on the maximum value of the temperature data of all groups, determine whether there are DC input terminals with abnormal temperatures among all DC input terminals and locate the positions of the DC input terminals with abnormal temperatures; the required controller interface resources are small, the hardware cost is low, and the precise positioning of temperature anomalies is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic diagram of a photovoltaic power generation system provided in an embodiment of the present application;

[0014] Figure 2 A schematic diagram of a control process of an inverter provided in an embodiment of the present application;

[0015] Figure 3 A schematic diagram of another control process of the inverter provided in an embodiment of the present application;

[0016] Figure 4 A schematic diagram of a control method for an inverter provided in an embodiment of the present application.

[0017] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer and more understandable, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0019] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "front", "back", "left", "right", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0020] like Figure 1As shown, the photovoltaic power generation system includes an inverter, the DC end of the inverter is connected to m DCDC units (shown as DCDC unit 1 to DCDC unit m in the figure), each DCDC unit is connected to at least n photovoltaic strings (shown as photovoltaic string 1 to photovoltaic string n in the figure), each photovoltaic string is composed of one or more photovoltaic cells connected in series and / or in parallel, and each photovoltaic string has a DC input terminal; wherein n and m are both positive integers. The AC end of the inverter is connected to the power grid.

[0021] Generally, the DC input terminals include a positive DC input terminal PV+ and a negative DC input terminal PV-.

[0022] The DCDC unit includes a power switch tube, and maximum power point tracking (MPPT) can be achieved through the DCDC unit.

[0023] The inverter further includes a temperature detection unit, a current detection unit and a control unit.

[0024] The temperature detection unit is used to detect the temperature data of the DC input terminal. The current detection unit is used to detect the current of the DCDC unit.

[0025] Based on the above inverter, in one example, the control unit is configured to obtain temperature data of all DC input terminals; number and group the temperature data of all DC input terminals, and obtain the maximum value of each group of temperature data; based on the maximum value of the temperature data of all groups, determine whether there is a DC input terminal with abnormal temperature among all DC input terminals and locate the position of the DC input terminal with abnormal temperature.

[0026] In one example, the control unit is configured to:

[0027] The temperature data of all DC input terminals are numbered with one of the serial number of the DC input terminal and the serial number of the DCDC unit as the row number and the other as the column number, and then the DC input terminals with the same serial number are grouped in the numbered temperature data.

[0028] In one example, the control unit is configured to:

[0029] The temperature data of all positive DC input terminals are numbered using one of the serial number of the positive DC input terminal and the serial number of the DCDC unit as the row number and the other as the column number, and then the positive DC input terminals with the same serial number are grouped in the numbered temperature data; or

[0030] Using one of the serial number of the negative DC input terminal and the serial number of the DCDC unit as the row number and the other as the column number, the temperature data of all negative DC input terminals are numbered, and then the negative DC input terminals with the same serial number are grouped in the numbered temperature data; or,

[0031] The temperature data of all positive DC input terminals and negative DC input terminals are numbered with one of the serial number of the DC input terminal and the serial number of the DCDC unit as the row number and the other as the column number, and then the DC input terminals with the same serial number are grouped in the numbered temperature data, and each group of the grouped temperature data includes only one type of temperature data of the positive DC input terminal and the negative DC input terminal with the same number.

[0032] In one example, the control unit is configured to number and group the temperature data of all DC input terminals in the following manner:

[0033] First, follow the following T ij The temperature data of all DC input terminals are numbered in a matrix relationship:

[0034]

[0035] Temperature data of the i-th DC input terminal of the j-th DCDC unit;

[0036] Then in the T ij In the matrix relationship, the terminals are grouped by rows, that is, the DC input terminals are grouped according to the same serial number.

[0037] In one example, the control unit is configured to:

[0038] Compare the maximum values ​​of the temperature data of all groups with the preset temperature thresholds one by one;

[0039] When the maximum value of the temperature data of any group is higher than the preset temperature threshold, it is determined that there is a DC input terminal with abnormal temperature among all the DC input terminals; otherwise, it is determined that there is no DC input terminal with abnormal temperature among all the DC input terminals.

[0040] In one example, the control unit is configured to:

[0041] The current of the DCDC unit is controlled to locate the position of the DC input terminal with abnormal temperature.

[0042] In one example, the control unit is configured to:

[0043] When it is determined that there is a DC input terminal with abnormal temperature among all the DC input terminals, recording the serial number of the DC input terminal;

[0044] Reducing the current of all DCDC units so that the maximum values ​​of the temperature data of all groups are lower than the preset temperature threshold;

[0045] The current of any DCDC unit is restored, and the temperature data of all DC input terminals are reacquired; the temperature data of all DC input terminals that are reacquired are numbered and grouped, and the maximum value of each group of temperature data is obtained again; based on the maximum value of the temperature data of all groups that are obtained again, it is determined again whether there is a DC input terminal with abnormal temperature among all DC input terminals;

[0046] If it is determined again that there is a DC input terminal with abnormal temperature among all the DC input terminals, the serial number of the DCDC unit is recorded;

[0047] The position of the DC input terminal with abnormal temperature is located according to the recorded serial number of the DC input terminal and the serial number of the DCDC unit.

[0048] In one example, the control unit is configured to:

[0049] reducing the current of any one of the DCDC units;

[0050] Any one DCDC unit is selected again from the remaining DCDC units to perform a current recovery action, and it is re-determined whether there is a DC input terminal with abnormal temperature among all the DC input terminals.

[0051] In one example, the control unit is configured to:

[0052] If it is determined again that there is no DC input terminal with abnormal temperature among all the DC input terminals, any one DCDC unit is selected again from the remaining DCDC units to perform a current recovery action, and it is determined again whether there is a DC input terminal with abnormal temperature among all the DC input terminals.

[0053] In one example, the control unit is configured to:

[0054] Determine whether all DCDC units perform current recovery action;

[0055] If all DCDC units have performed current recovery, the position of the DC input terminal with abnormal temperature is located according to the recorded serial number of the DC input terminal and the serial number of the DCDC unit; otherwise, any DCDC unit is selected again from the remaining DCDC units to perform current recovery.

[0056] In one example, the control unit is configured to:

[0057] When it is determined that there is a DC input terminal with abnormal temperature among all the DC input terminals, recording the serial number of the DC input terminal;

[0058] The current of any DCDC unit is reduced, and the temperature data of all DC input terminals are re-acquired; the temperature data of all DC input terminals that are re-acquired are numbered and grouped, and the maximum value of each group of temperature data is obtained again; based on the maximum value of the temperature data of all groups that are obtained again, it is determined again whether there is a DC input terminal with abnormal temperature among all DC input terminals;

[0059] If it is determined again that there is no DC input terminal with abnormal temperature among all the DC input terminals, the serial number of the DCDC unit;

[0060] The position of the DC input terminal with abnormal temperature is located according to the recorded serial number of the DC input terminal and the serial number of the DCDC unit.

[0061] In one example, the control unit is configured to:

[0062] If it is determined again that there is a DC input terminal with abnormal temperature among all the DC input terminals, any one DCDC unit is selected again from the remaining DCDC units to perform a current reduction action, and it is determined again whether there is a DC input terminal with abnormal temperature among all the DC input terminals.

[0063] In one example, the control unit is configured to:

[0064] Determine whether all DCDC units are performing current reduction actions;

[0065] If all DCDC units have performed the current reduction action, the position of the DC input terminal with abnormal temperature is located according to the recorded serial number of the DC input terminal and the serial number of the DCDC unit; otherwise, any one DCDC unit is selected again from the remaining DCDC units to perform the current reduction action, and it is re-determined whether there is a DC input terminal with abnormal temperature among all the DC input terminals.

[0066] It should be noted that the above-mentioned “higher than” or “lower than” includes the situation of “equal to”. It is understandable that in the same type of criterion, only one of “higher than” and “lower than” includes the situation of “equal to”.

[0067] In order to achieve accurate positioning, the temperature of each DC input terminal needs to be sampled. For m DCDC units, each unit has n photovoltaic strings connected. The hardware needs 2mn complete sampling circuits to sample 2mn temperature data. Even if K-select-1 chips (through clock control, one data is selected from K data each time) are used to process the data, at least ceil (log 2 K)+ceil(2mn / K) (ceil means rounding up) control unit ports, ceil(2mn / K) K-select-1 chips and peripheral hardware circuits. This causes the problem of excessive consumption of control chip ports or even insufficient chip ports to complete sampling, which increases hardware costs and also brings excessive waste of chip port resources.

[0068] The solution proposed in this application only needs to sample 2mn temperatures. By grouping, only 2n temperature data are collected. Then, through the K-select-1 chip (through clock control, 1 data is selected from K data each time), 2n temperature sampling can be achieved. This solution only consumes ceil (log 2 K) + ceil (2n / K) control unit ports, ceil (2n / K) K-choose-1 chips and peripheral hardware circuits, together with the current detection unit and control unit required by the inverter, can accurately locate the position of the DC input terminal with abnormal temperature. The required control chip port resources are small, the hardware cost is low, and the accurate positioning of temperature anomalies is achieved.

[0069] The following combination Figure 2 The control process of the inverter is described. Figure 2 As shown, the control process steps of the inverter are:

[0070] S11. Collect temperature data of the DC input terminal, record it as Tij, group Tij by row, and take the maximum value in each row.

[0071] The DC input terminals include a positive DC input terminal PV+ and a negative DC input terminal PV-. When the temperature data of each DC input terminal is detected, there are 2mn temperature points in total.

[0072] Taking the positive DC input terminal PV+ as an example, the temperature data of the positive DC input terminal PV+ is recorded as T ij-PV+ (i∈[1,n],j∈[1,m]), i and j represent serial numbers, which means the temperature data of the positive DC input terminal PV+ of the i-th photovoltaic string in the j-th DCDC unit. It can be expressed in matrix as:

[0073]

[0074] In T ij-PV+In the matrix formed, grouping is done by row and taking the maximum value, then at least n temperature data can be obtained. The negative DC input terminal PV- is similar to this. ij-PV- In the matrix formed, grouping is done by row and taking the maximum value, and at least n temperature data can be obtained. In this way, 2n temperature data can be obtained.

[0075] S12. Determine whether the temperature is normal?

[0076] The maximum values ​​of the temperature data of all groups are compared with the preset temperature threshold value one by one; when the maximum value of the temperature data of any group is higher than the preset temperature threshold value, it is determined that there is a DC input terminal with abnormal temperature among all the DC input terminals, that is, the temperature is abnormal, and step S13 can be executed at this time; otherwise, it is determined that there is no DC input terminal with abnormal temperature among all the DC input terminals, that is, the temperature is normal, and the process ends at this time.

[0077] S13, reducing the current of all DCDC units until the temperatures of all DC input terminals are normal.

[0078] The current of the DCDC unit can be reduced by controlling the power switch tube in the DCDC unit.

[0079] S14, restore the current of any DCDC unit and re-collect the temperature data.

[0080] That is, according to step S11, the temperature data of the DC input terminal is collected and recorded as Tij, Tij is grouped by rows, and the maximum value of each row is taken.

[0081] S15. Determine whether the temperature is normal?

[0082] Similar to step S12, it is determined again whether the temperature is normal. If the temperature is abnormal, step S16 is performed, and if the temperature is normal, step S17 is performed.

[0083] S16, record the row number and column number of the abnormal temperature data, reduce the DCDC unit current, and then execute step S17.

[0084] S17. Do all units perform current recovery action?

[0085] If all DCDC units have performed the current recovery action, then step S18 is executed; otherwise, step S14 is continued. When step S14 is continued, any one DCDC unit needs to be selected again from the remaining DCDC units to perform the current recovery action.

[0086] S18. Locate the DC input terminal with abnormal temperature.

[0087] According to the row number and column number of the recorded abnormal temperature data, the position of the DC input terminal with abnormal temperature can be located, for example, the positive DC input terminal PV+ of the second PV string in the first DCDC unit has abnormal temperature.

[0088] The following combination Figure 3 Another control process of the inverter is described. Figure 3 As shown, the control process steps of the inverter are:

[0089] S21. Collect temperature data of the DC input terminal, record it as Tij, group Tij by row, and take the maximum value in each row.

[0090] The DC input terminals include a positive DC input terminal PV+ and a negative DC input terminal PV-. When the temperature data of each DC input terminal is detected, there are 2mn temperature points in total.

[0091] Taking the positive DC input terminal PV+ as an example, the temperature data of the positive DC input terminal PV+ is recorded as T ij-PV+ (i∈[1,n],j∈[1,m]), i and j represent serial numbers, which means the temperature data of the positive DC input terminal PV+ of the i-th photovoltaic string in the j-th DCDC unit. It can be expressed in matrix as:

[0092]

[0093] In T ij-PV+ In the matrix formed, grouping is done by row and taking the maximum value, then at least n temperature data can be obtained. The negative DC input terminal PV- is similar. It can be understood that in the above matrix, it is also possible to swap the rows and columns, that is, the serial number of the PV string is used as the column number, and the serial number of the DCDC unit is used as the row number.

[0094] S22. Determine whether the temperature is normal?

[0095] The maximum values ​​of the temperature data of all groups are compared with the preset temperature threshold value one by one; when the maximum value of the temperature data of any group is higher than the preset temperature threshold value, it is determined that there is a DC input terminal with abnormal temperature among all the DC input terminals, that is, the temperature is abnormal, and step S23 can be executed at this time; otherwise, it is determined that there is no DC input terminal with abnormal temperature among all the DC input terminals, that is, the temperature is normal, and the process ends at this time.

[0096] S23. Record the row number of abnormal temperature data.

[0097] S24, reducing the current of any DCDC unit and re-collecting temperature data.

[0098] The current of the DCDC unit can be reduced by controlling the power switch tube in the DCDC unit, and the temperature data of the DC input terminal is collected according to step S11, recorded as Tij, Tij is grouped by row, and the maximum value of each row is taken.

[0099] S25. Determine whether the temperature is normal?

[0100] Similar to step S22, it is determined again whether the temperature is normal. If the temperature is normal, step S26 is performed, and if the temperature is abnormal, step S27 is performed.

[0101] S26. Record the column number of the abnormal temperature data, and then execute step S27.

[0102] S27. Do all units perform current reduction action?

[0103] If all DCDC units have performed the current reduction action, then step S28 is executed; otherwise, step S24 is continued. When step S24 is continued, any one DCDC unit needs to be selected again from the remaining DCDC units to perform the current reduction action.

[0104] S28. Locate the DC input terminal with abnormal temperature.

[0105] According to the row number and column number of the recorded abnormal temperature data, the position of the DC input terminal with abnormal temperature can be located, for example, the positive DC input terminal PV+ of the second PV string in the first DCDC unit has abnormal temperature.

[0106] Figure 4 This is a schematic diagram of a control method for an inverter provided in another embodiment of the present application. The inverter may refer to the above content. The control method comprises the steps of:

[0107] S31, obtaining temperature data of all DC input terminals;

[0108] S32, numbering and grouping the temperature data of all DC input terminals, and obtaining the maximum value of each group of temperature data;

[0109] S33. Based on the maximum value of the temperature data of all groups, determine whether there is a DC input terminal with abnormal temperature among all the DC input terminals and locate the position of the DC input terminal with abnormal temperature.

[0110] In one example, numbering and grouping the temperature data of all DC input terminals includes:

[0111] The temperature data of all DC input terminals are numbered with one of the serial number of the DC input terminal and the serial number of the DCDC unit as the row number and the other as the column number, and then the DC input terminals with the same serial number are grouped in the numbered temperature data.

[0112] In one example, the temperature data of all DC input terminals are numbered using one of the serial number of the DC input terminal and the serial number of the DCDC unit as a row number and the other as a column number, and then the DC input terminals with the same serial number are grouped in the numbered temperature data, including:

[0113] The temperature data of all positive DC input terminals are numbered using one of the serial number of the positive DC input terminal and the serial number of the DCDC unit as the row number and the other as the column number, and then the positive DC input terminals with the same serial number are grouped in the numbered temperature data; or

[0114] Using one of the serial number of the negative DC input terminal and the serial number of the DCDC unit as the row number and the other as the column number, the temperature data of all negative DC input terminals are numbered, and then the negative DC input terminals with the same serial number are grouped in the numbered temperature data; or,

[0115] The temperature data of all positive DC input terminals and negative DC input terminals are numbered with one of the serial number of the DC input terminal and the serial number of the DCDC unit as the row number and the other as the column number, and then the DC input terminals with the same serial number are grouped in the numbered temperature data, and each group of the grouped temperature data includes only one type of temperature data of the positive DC input terminal and the negative DC input terminal with the same number.

[0116] In one example, the temperature data of all DC input terminals are numbered and grouped as follows:

[0117] First, follow the following T ij The temperature data of all DC input terminals are numbered in a matrix relationship:

[0118] Where T ij represents the temperature data of the i-th DC input terminal of the j-th DCDC unit;

[0119] Then in the T ij Matrix relations are grouped by rows.

[0120] In one example, determining whether there is a DC input terminal with abnormal temperature among all DC input terminals includes:

[0121] Compare the maximum values ​​of the temperature data of all groups with the preset temperature thresholds one by one;

[0122] When the maximum value of the temperature data of any group is higher than the preset temperature threshold, it is determined that there is a DC input terminal with abnormal temperature among all the DC input terminals; otherwise, it is determined that there is no DC input terminal with abnormal temperature among all the DC input terminals.

[0123] In one example, locating the position of the DC input terminal with abnormal temperature includes:

[0124] The current of the DCDC unit is controlled to locate the position of the DC input terminal with abnormal temperature.

[0125] In one example, controlling the current of the DCDC unit to locate the position of the DC input terminal with abnormal temperature includes:

[0126] When it is determined that there is a DC input terminal with abnormal temperature among all the DC input terminals, recording the serial number of the DC input terminal;

[0127] Reducing the current of all DCDC units so that the maximum values ​​of the temperature data of all groups are lower than the preset temperature threshold;

[0128] The current of any DCDC unit is restored, and the temperature data of all DC input terminals are reacquired; the temperature data of all DC input terminals that are reacquired are numbered and grouped, and the maximum value of each group of temperature data is obtained again; based on the maximum value of the temperature data of all groups that are obtained again, it is determined again whether there is a DC input terminal with abnormal temperature among all DC input terminals;

[0129] If it is determined again that there is a DC input terminal with abnormal temperature among all the DC input terminals, the serial number of the DCDC unit is recorded;

[0130] The position of the DC input terminal with abnormal temperature is located according to the recorded serial number of the DC input terminal and the serial number of the DCDC unit.

[0131] In one example, the serial number of the DC input terminal and the serial number of the DCDC unit recorded also include:

[0132] reducing the current of any one of the DCDC units;

[0133] Any one DCDC unit is selected again from the remaining DCDC units to perform a current recovery action, and it is re-determined whether there is a DC input terminal with abnormal temperature among all the DC input terminals.

[0134] In one example, after determining again whether there is a DC input terminal with abnormal temperature among all the DC input terminals, the method further includes:

[0135] If it is determined again that there is no DC input terminal with abnormal temperature among all the DC input terminals, any one DCDC unit is selected again from the remaining DCDC units to perform a current recovery action, and it is determined again whether there is a DC input terminal with abnormal temperature among all the DC input terminals.

[0136] In one example, before selecting any one DCDC unit from the remaining DCDC units again to perform the current recovery action, the step further includes:

[0137] Determine whether all DCDC units perform current recovery action;

[0138] If all DCDC units have performed current recovery, the position of the DC input terminal with abnormal temperature is located according to the recorded serial number of the DC input terminal and the serial number of the DCDC unit; otherwise, any DCDC unit is selected again from the remaining DCDC units to perform current recovery.

[0139] In one example, controlling the current of the DCDC unit to locate the position of the DC input terminal with abnormal temperature includes:

[0140] When it is determined that there is a DC input terminal with abnormal temperature among all the DC input terminals, recording the serial number of the DC input terminal;

[0141] The current of any DCDC unit is reduced, and the temperature data of all DC input terminals are re-acquired; the temperature data of all DC input terminals that are re-acquired are numbered and grouped, and the maximum value of each group of temperature data is obtained again; based on the maximum value of the temperature data of all groups that are obtained again, it is determined again whether there is a DC input terminal with abnormal temperature among all DC input terminals;

[0142] If it is determined again that there is no DC input terminal with abnormal temperature among all the DC input terminals, the serial number of the DCDC unit is recorded;

[0143] The position of the DC input terminal with abnormal temperature is located according to the recorded serial number of the DC input terminal and the serial number of the DCDC unit.

[0144] In one example, after determining again whether there is a DC input terminal with abnormal temperature among all the DC input terminals, the method further includes:

[0145] If it is determined again that there is a DC input terminal with abnormal temperature among all the DC input terminals, any one DCDC unit is selected again from the remaining DCDC units to perform a current reduction action, and it is determined again whether there is a DC input terminal with abnormal temperature among all the DC input terminals.

[0146] In one example, the abnormal temperature data recorded according to the row number and column number also includes:

[0147] Determine whether all DCDC units are performing current reduction actions;

[0148] If all DCDC units have performed the current reduction action, the position of the DC input terminal with abnormal temperature is located according to the recorded serial number of the DC input terminal and the serial number of the DCDC unit; otherwise, any one DCDC unit is selected again from the remaining DCDC units to perform the current reduction action, and it is re-determined whether there is a DC input terminal with abnormal temperature among all the DC input terminals.

[0149] The preferred embodiments of the present application are described above with reference to the accompanying drawings, but the scope of the present application is not limited thereby. Any modification, equivalent substitution and improvement made by a person skilled in the art without departing from the scope and essence of the present application shall be within the scope of the present application.

Claims

1. A control method for an inverter, characterized in that: The DC end of the inverter is connected to m DCDC units, each DCDC unit is connected to at least n photovoltaic strings, and each photovoltaic string has a DC input terminal; wherein n and m are both positive integers; The control method comprises: Get the temperature data of all DC input terminals; The temperature data of all DC input terminals are numbered and grouped, and the maximum value of each group of temperature data is obtained; Based on the maximum value of the temperature data of all the groups, it is determined whether there is a DC input terminal with abnormal temperature among all the DC input terminals and the position of the DC input terminal with abnormal temperature is located.

2. The control method according to claim 1, characterized in that: The step of numbering and grouping the temperature data of all DC input terminals includes: The temperature data of all DC input terminals are numbered with one of the serial number of the DC input terminal and the serial number of the DCDC unit as the row number and the other as the column number, and then the DC input terminals with the same serial number are grouped in the numbered temperature data.

3. The control method according to claim 2, characterized in that: The method of numbering the temperature data of all DC input terminals using one of the serial number of the DC input terminal and the serial number of the DCDC unit as a row number and the other as a column number, and then grouping the DC input terminals with the same serial number in the numbered temperature data comprises: The temperature data of all positive DC input terminals are numbered using one of the serial number of the positive DC input terminal and the serial number of the DCDC unit as the row number and the other as the column number, and then the positive DC input terminals with the same serial number are grouped in the numbered temperature data; or Using one of the serial number of the negative DC input terminal and the serial number of the DCDC unit as the row number and the other as the column number, the temperature data of all negative DC input terminals are numbered, and then the negative DC input terminals with the same serial number are grouped in the numbered temperature data; or, The temperature data of all positive DC input terminals and negative DC input terminals are numbered with one of the serial number of the DC input terminal and the serial number of the DCDC unit as the row number and the other as the column number, and then the DC input terminals with the same serial number are grouped in the numbered temperature data, and each group of the grouped temperature data includes only one type of temperature data of the positive DC input terminal and the negative DC input terminal with the same number.

4. The control method according to claim 1, characterized in that: The step of determining whether there is a DC input terminal with abnormal temperature among all DC input terminals includes: Compare the maximum values ​​of the temperature data of all groups with the preset temperature thresholds one by one; When the maximum value of the temperature data of any group is higher than the preset temperature threshold, it is determined that there is a DC input terminal with abnormal temperature among all the DC input terminals; otherwise, it is determined that there is no DC input terminal with abnormal temperature among all the DC input terminals.

5. The control method according to claim 1, characterized in that: The step of locating the position of the DC input terminal with abnormal temperature includes: The current of the DCDC unit is controlled to locate the position of the DC input terminal with abnormal temperature.

6. The control method according to claim 5, characterized in that: The controlling the current of the DCDC unit to locate the position of the DC input terminal with abnormal temperature includes: When it is determined that there is a DC input terminal with abnormal temperature among all the DC input terminals, recording the serial number of the DC input terminal; Reducing the current of all DCDC units so that the maximum values ​​of the temperature data of all groups are lower than the preset temperature threshold; The current of any DCDC unit is restored, and the temperature data of all DC input terminals are reacquired; the temperature data of all DC input terminals that are reacquired are numbered and grouped, and the maximum value of each group of temperature data is obtained again; based on the maximum value of the temperature data of all groups that are obtained again, it is determined again whether there is a DC input terminal with abnormal temperature among all DC input terminals; If it is determined again that there is a DC input terminal with abnormal temperature among all the DC input terminals, the serial number of the DCDC unit is recorded; The position of the DC input terminal with abnormal temperature is located according to the recorded serial number of the DC input terminal and the serial number of the DCDC unit.

7. The control method according to claim 6, characterized in that: The method further includes before the serial number of the DC input terminal and the serial number of the DCDC unit recorded: reducing the current of any one of the DCDC units; Any one DCDC unit is selected again from the remaining DCDC units to perform a current recovery action, and it is re-determined whether there is a DC input terminal with abnormal temperature among all the DC input terminals.

8. The control method according to claim 6, characterized in that: After determining again whether there is a DC input terminal with abnormal temperature among all the DC input terminals, the method further includes: If it is determined again that there is no DC input terminal with abnormal temperature among all the DC input terminals, any one DCDC unit is selected again from the remaining DCDC units to perform a current recovery action, and it is determined again whether there is a DC input terminal with abnormal temperature among all the DC input terminals.

9. The control method according to claim 7 or 8, characterized in that: Before selecting any one DCDC unit from the remaining DCDC units again to perform the current recovery action, the method further includes: Determine whether all DCDC units perform current recovery action; If all DCDC units have performed current recovery, the position of the DC input terminal with abnormal temperature is located according to the recorded serial number of the DC input terminal and the serial number of the DCDC unit; otherwise, any DCDC unit is selected again from the remaining DCDC units to perform current recovery.

10. The control method according to claim 5, characterized in that: The controlling the current of the DCDC unit to locate the position of the DC input terminal with abnormal temperature includes: When it is determined that there is a DC input terminal with abnormal temperature among all the DC input terminals, recording the serial number of the DC input terminal; The current of any DCDC unit is reduced, and the temperature data of all DC input terminals are re-acquired; the temperature data of all DC input terminals that are re-acquired are numbered and grouped, and the maximum value of each group of temperature data is obtained again; based on the maximum value of the temperature data of all groups that are obtained again, it is determined again whether there is a DC input terminal with abnormal temperature among all DC input terminals; If it is determined again that there is no DC input terminal with abnormal temperature among all the DC input terminals, the serial number of the DCDC unit is recorded; The position of the DC input terminal with abnormal temperature is located according to the recorded serial number of the DC input terminal and the serial number of the DCDC unit.

11. The control method according to claim 10, characterized in that: After determining again whether there is a DC input terminal with abnormal temperature among all the DC input terminals, the method further includes: If it is determined again that there is a DC input terminal with abnormal temperature among all the DC input terminals, any one DCDC unit is selected again from the remaining DCDC units to perform a current reduction action, and it is determined again whether there is a DC input terminal with abnormal temperature among all the DC input terminals.

12. The control method according to claim 10, characterized in that: The method further includes before the serial number of the DC input terminal and the serial number of the DCDC unit recorded: Determine whether all DCDC units are performing current reduction actions; If all DCDC units have performed the current reduction action, the position of the DC input terminal with abnormal temperature is located according to the recorded serial number of the DC input terminal and the serial number of the DCDC unit; otherwise, any one DCDC unit is selected again from the remaining DCDC units to perform the current reduction action, and it is re-determined whether there is a DC input terminal with abnormal temperature among all the DC input terminals.

13. An inverter, characterized in that: The DC end of the inverter is connected to m DCDC units, each DCDC unit is connected to at least n photovoltaic strings, and each photovoltaic string has a DC input terminal; wherein n and m are both positive integers; The inverter further includes a control unit, which is configured to execute the control method according to any one of claims 1 to 12.

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