Inverter control method and inverter system

Abstract

The invention discloses an inverter control method and an inverter system, and belongs to the field of inverters. The control method of the inverter comprises the following steps: in an off-grid scene, obtaining a difference degree between a bus voltage and an output voltage of the inverter and a target limit value corresponding to an output electric signal of the inverter; and limiting an output electric signal of the inverter based on a target limiting value under the condition of determining to enter a derating control scene based on the difference degree so as to suppress positive feedback of the inverter in a derating control process. According to the control method of the inverter, on the basis that the output current is limited according to the difference degree of the bus voltage and the output voltage of the inverter so as to reduce inversion inductance heating, positive feedback of the inverter in the derating control process can be effectively restrained, normal operation of the inverter is guaranteed, and the power utilization requirement is met.

Description

Technical Field

[0001] This application belongs to the field of inverters, and particularly relates to a control method for an inverter and an inverter system. Background Art

[0002] Inverters are widely used in power generation and power consumption scenarios. To ensure the safety of inverter operation and extend the service life of the inverter, it is necessary to avoid excessive ripple on the inverter inductor. In related technologies, most of the solutions for reducing excessive ripple on the inductor are control solutions for grid-connected scenarios and cannot be applied to off-grid scenarios. As a result, in the off-grid scenario, the inverter is prone to excessive ripple on the inverter inductor, causing overheating, which may lead to damage to the inverter inductor or other components, affecting the safety of inverter operation and the service life of the inverter. Summary of the Invention

[0003] This application aims to solve at least one of the technical problems existing in the prior art. For this purpose, this application provides a control method for an inverter and an inverter system, which can limit the output current according to the difference between the inverter bus voltage and the output voltage to reduce the heating of the inverter inductor and extend the service life of the inverter. On this basis, it can effectively suppress the positive feedback during the derating control of the inverter, ensure the normal operation of the inverter, and meet the power consumption requirements.

[0004] In a first aspect, this application provides a control method for an inverter, and the method includes:

[0005] In an off-grid scenario, obtain the difference between the bus voltage and the output voltage of the inverter, and the target limit value corresponding to the output electrical signal of the inverter;

[0006] When it is determined to enter the derating control scenario based on the difference, limit the output electrical signal of the inverter based on the target limit value to suppress the positive feedback during the derating control of the inverter.

[0007] According to the control method of the inverter of this application, it is determined whether to enter the derating control scenario through the difference, and the inverter is derated based on the positive feedback generated during the derating control. It can limit the output current according to the difference between the inverter bus voltage and the output voltage to reduce the heating of the inverter inductor and extend the service life of the inverter. On this basis, it can effectively suppress the positive feedback during the derating control of the inverter, ensure the normal operation of the inverter, and meet the power consumption requirements; and it is applicable to the off-grid operation scenario and has universality.

[0008] According to an embodiment of this application, the determination of entering the derating control scenario based on the difference includes:

[0009] When it is determined that the difference degree is greater than the first threshold and the operating state of the inverter is not the target state, it is determined to enter the derating control scenario; the target state includes the startup stage or the overload stage.

[0010] According to an embodiment of the present application, the startup stage is determined according to the following steps:

[0011] Within the first time period since the startup moment of the inverter, it is determined that the inverter operates in the startup stage;

[0012] Or,

[0013] Since the startup moment of the inverter until the output voltage of the inverter is not less than the startup voltage judgment threshold, it is determined that the inverter operates in the startup stage.

[0014] According to an embodiment of the present application, the overload stage is determined according to the following steps:

[0015] Since the moment when the output current of the inverter is greater than the overload recognition threshold, within the second time period, it is determined that the inverter operates in the overload stage.

[0016] According to an embodiment of the present application, when it is determined to enter the derating control scenario based on the difference degree, based on the target limit value, restricting the output electrical signal of the inverter includes:

[0017] When it is determined to enter the derating control scenario based on the difference degree, based on the target limit value, perform a delay restriction on the output electrical signal of the inverter.

[0018] According to an embodiment of the present application, performing a delay restriction on the output electrical signal of the inverter based on the target limit value includes:

[0019] After the target delay time period and when the difference degree is greater than the first threshold, based on the target limit value, restrict the output electrical signal of the inverter.

[0020] According to an embodiment of the present application, performing a delay restriction on the output electrical signal of the inverter based on the target limit value includes:

[0021] Perform low-pass filtering on the target limit value, and based on the target limit value after low-pass filtering, restrict the output electrical signal of the inverter.

[0022] According to an embodiment of the present application, obtaining the target limit value corresponding to the output electrical signal of the inverter includes:

[0023] Obtain the target limit value of the output electrical signal corresponding to the degree of difference.

[0024] According to an embodiment of the present application, the obtaining the target limit value of the output electrical signal corresponding to the degree of difference includes:

[0025] Query a preset association table to obtain at least one candidate limit value that matches the degree of difference; the preset association table includes multiple candidate degrees of difference and candidate limit values corresponding to the candidate degrees of difference;

[0026] Based on the at least one candidate limit value, determine the target limit value.

[0027] According to an embodiment of the present application, the obtaining the target limit value of the output electrical signal corresponding to the degree of difference includes:

[0028] According to the actual temperature of the inverter and the degree of difference, obtain the target limit value that matches the actual temperature and the degree of difference.

[0029] According to an embodiment of the present application, the suppressing the positive feedback during the derating control of the inverter includes:

[0030] Determine whether to enter the derating control scenario based on the degree of difference and the operating state of the inverter, and / or perform a time-delay derating control on the inverter to suppress the positive feedback during the derating control of the inverter.

[0031] In a second aspect, the present application provides a control device for an inverter, and the device includes:

[0032] A first processing module, configured to obtain the degree of difference between the bus voltage and the output voltage of the inverter, and the target limit value corresponding to the output electrical signal of the inverter in an off-grid scenario;

[0033] A second processing module, configured to, when it is determined to enter the derating control scenario based on the degree of difference, limit the output electrical signal of the inverter based on the target limit value to suppress the positive feedback during the derating control of the inverter.

[0034] According to the control device for an inverter of the present application, it is possible to determine whether to enter the derating control scenario through the degree of difference, and perform derating control on the inverter in combination with the positive feedback generated during the derating control process. On the basis of reducing the heating of the inverter inductance by limiting the output current according to the difference between the bus voltage and the output voltage of the inverter and extending the service life of the inverter, it can effectively suppress the positive feedback during the derating control of the inverter, ensure the normal operation of the inverter, and meet the power consumption requirements; and it is applicable to the off-grid operation scenario and has universality.

[0035] In a third aspect, the present application provides an inverter system, including an inverter that operates based on the control method of the inverter as described in the first aspect.

[0036] In a fourth aspect, the present application provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the control method of the inverter as described in the first aspect above.

[0037] In a fifth aspect, the present application provides a computer program product, including a computer program that, when executed by a processor, implements the control method of the inverter as described in the first aspect above.

[0038] One or more of the above technical solutions in the embodiments of the present application have at least one of the following technical effects:

[0039] By determining whether to enter the derating control scenario through the difference degree, and combining the positive feedback situation generated during the process of entering the derating control to perform derating control on the inverter, it is possible to limit the output current according to the difference between the inverter bus voltage and the output voltage to reduce the heating of the inverter inductance and extend the life of the inverter. On this basis, the positive feedback during the derating control process of the inverter can be effectively suppressed, ensuring the normal operation of the inverter and meeting the power consumption requirements; and it is applicable to the off-grid operation scenario, with universality.

[0040] Furthermore, by determining whether to enter the derating control scenario through the difference degree, and determining whether to enter the derating control scenario based on the difference degree and the operating state of the inverter, and / or by performing delayed derating control on the inverter, the positive feedback during the derating control process of the inverter can be suppressed, ensuring the normal operation of the inverter and meeting the power consumption requirements.

[0041] Even further, when it is determined to enter the derating control scenario based on the difference degree, by delaying the limitation of the output electrical signal of the inverter based on the target limit value, it is possible to ensure that the load increase during transient conditions does not cause positive feedback shutdown without damaging the inverter, improve the robustness of the system, and ensure the normal power supply of the system.

[0042] Still further, by combining the difference between the bus voltage and the output voltage of the inverter and the actual temperature of the inverter to jointly determine the corresponding target limit value, it is possible to combine the change of its own temperature and the external environment situation. When the difference between the bus voltage and the output voltage of the inverter is certain, the higher the temperature of the inverter inductance, the smaller the derated output, reducing the probability of damage to the inverter inductance or other devices caused by excessive ripple heating on the inverter inductance, being able to flexibly respond to complex scenario environment changes in the actual operation scenario, further improving the accuracy of derating control, effectively limiting the heating of the inverter inductance, maintaining the stable operation of the inverter, and extending the life of the inverter.

[0043] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0044] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, where:

[0045] Figure 1 is one of the schematic flowcharts of the control method of the inverter provided by the embodiment of the present application;

[0046] Figure 2 is one of the schematic diagrams of the results of the control method of the inverter provided by the embodiment of the present application;

[0047] Figure 3 is the second schematic diagram of the results of the control method of the inverter provided by the embodiment of the present application;

[0048] Figure 4 is the third schematic diagram of the results of the control method of the inverter provided by the embodiment of the present application;

[0049] Figure 5 is the schematic structural diagram of the control device of the inverter provided by the embodiment of the present application;

[0050] Figure 6 is the schematic structural diagram of the electronic device provided by the embodiment of the present application. Detailed Embodiments

[0051] The technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application fall within the scope of protection of the present application.

[0052] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and do not limit the number of objects. For example, the first object can be one or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / ", generally represents an "or" relationship between the associated objects before and after.

[0053] The following will combine the accompanying drawings and, through specific embodiments and their application scenarios, elaborate in detail on the control method of the inverter, the control device of the inverter, the electronic device, and the readable storage medium provided by the embodiments of the present application.

[0054] Among them, the control method of the inverter can be applied to a terminal and can be specifically executed by the hardware or software in the terminal.

[0055] For the control method of the inverter provided by the embodiments of the present application, the execution subject of the control method of the inverter can be an electronic device or a functional module or functional entity in the electronic device that can implement the control method of the inverter. The electronic devices mentioned in the embodiments of the present application include but are not limited to mobile phones, tablet computers, computers, cameras, and wearable devices, etc. The following will take the electronic device as the execution subject to illustrate the control method of the inverter provided by the embodiments of the present application.

[0056] As Figure 1 shown, the control method of the inverter includes: step 110 and step 120.

[0057] The control method of the inverter can be used in off-grid operation scenarios, grid-connected operation scenarios, etc.

[0058] The inverter can be a photovoltaic storage inverter applied to a photovoltaic power generation scenario, or it can also be an inverter used in a pure energy storage power supply scenario or other new energy power generation scenarios.

[0059] The inverter can be a single-phase inverter, or it can also be a multi-phase inverter.

[0060] Step 110: In an off-grid scenario, obtain the difference degree between the bus voltage and the output voltage of the inverter, and the target limit value corresponding to the output electrical signal of the inverter;

[0061] In this step, the output electrical signal can be the output current, output power, etc.; the difference degree can be in the form of a difference or a ratio, and the present application does not make a limitation here.

[0062] The output voltage of the inverter can be characterized by the effective value of the output phase voltage, the peak value of the phase voltage, the effective value of the line voltage, the peak value of the line voltage, etc.; in some embodiments, for a multi-phase inverter, the maximum value or the average value of each phase output voltage can also be determined as the output voltage of the inverter, which can be specifically set according to actual needs, and the present application does not make a limitation here.

[0063] The target limit value is the maximum value allowed for the output electrical signal of the inverter during the derating control process of the inverter, so that the output electrical signal of the inverter does not exceed this target limit value.

[0064] The target limit value can be a fixed value or a changing value. In some embodiments, the target limit value can be set according to user-defined settings.

[0065] In some embodiments, obtaining the target limit value corresponding to the output electrical signal of the inverter may include:

[0066] Obtaining the target limit value of the output electrical signal corresponding to the degree of difference.

[0067] In this embodiment, the target limit value can be adjusted correspondingly according to the change of the degree of difference. For example, through a pre-trained network model, the corresponding target limit value can be predicted according to the difference between the bus voltage and the output voltage of the inverter.

[0068] It can be understood that the greater the absolute value of the degree of difference, the relatively smaller the corresponding target limit value.

[0069] In some embodiments, in step 110, obtaining the target limit value of the output electrical signal corresponding to the degree of difference may include:

[0070] Querying a preset association table to obtain at least one candidate limit value matching the degree of difference;

[0071] Based on at least one candidate limit value, determining the target limit value.

[0072] In this embodiment, the preset association table includes multiple candidate degrees of difference and the candidate limit values corresponding to the candidate degrees of difference. The candidate limit value is the maximum output current allowed by the inverter under its corresponding candidate degree of difference. This preset association table can be obtained through theoretical calculation or experimental testing. Table 1 exemplifies a preset association table.

[0073] Table 1

[0074] Candidate difference degree / V 200 300 400 500 Candidate limit value / A 50 45 30 10

[0075] In some embodiments, the candidate degree of difference can be a specific value or a range interval. In the actual execution process, when the degree of difference is within this range interval, the candidate limit value corresponding to this range interval can be determined as the target limit value.

[0076] In some embodiments, the candidate limit value corresponding to the candidate degree of difference closest to the degree of difference in the preset association table can also be determined as the target limit value; or the candidate limit values corresponding to two candidate degrees of difference close to the degree of difference are screened from the preset association table, and these two candidate limit values are interpolated to obtain the target limit value. Taking Table 1 as an example, when the current degree of difference is 450V, according to the data in the preset association table for linear interpolation, the target limit value is determined to be 20A.

[0077] According to the inverter control method provided by the embodiments of the present application, by setting different limit values corresponding to different degrees of difference, the control accuracy of derating control can be improved.

[0078] In some embodiments, in step 110, obtaining the target limit value of the output electrical signal corresponding to the degree of difference may include:

[0079] Obtaining the target limit value that matches the actual temperature and the degree of difference according to the actual temperature and the degree of difference of the inverter.

[0080] In this embodiment, different preset association tables can be set corresponding to different temperature ranges during the operation of the inverter. According to the actual temperature of the inverter, the corresponding preset association table in the temperature range is selected. By looking up the preset association table, the maximum allowable output electrical signal under the current actual temperature and the degree of difference can be obtained.

[0081] Of course, in other embodiments, it is also possible to obtain the limit values corresponding to the output electrical signals under the degree of difference between the bus voltage and the output voltage of multiple inverters at different inverter temperatures as training samples to train the network models corresponding to different temperatures. In the actual application process, through the network model matching the actual temperature, the corresponding target limit value is output according to the degree of difference.

[0082] According to the inverter control method provided by the embodiments of the present application, by combining the degree of difference between the bus voltage and the output voltage of the inverter and the actual temperature of the inverter to jointly determine the corresponding target limit value, it is possible to combine its own temperature change and the external environment situation. When the degree of difference between the bus voltage and the output voltage of the inverter is certain, the higher the temperature of the inverter inductance, the smaller the derated output, reducing the probability of damage to the inverter inductance or other components caused by excessive ripple heating on the inverter inductance. It can flexibly respond to complex scenario environment changes in the actual operation scenario, further improve the accuracy of derating control, effectively limit the heating of the inverter inductance, maintain the stable operation of the inverter, and extend the life of the inverter.

[0083] Step 120, in the case of determining to enter the derating control scenario based on the degree of difference, limit the output electrical signal of the inverter based on the target limit value to suppress the positive feedback during the derating control process of the inverter.

[0084] In this step, it is necessary to judge whether the conditions for entering the derating control scenario are met according to the size of the degree of difference between the bus voltage and the output voltage of the inverter and other situations. If the conditions for entering the derating control scenario are not met, there is no need to limit the output electrical signal.

[0085] When it is determined that the conditions for entering the derating control scenario are met, it is also necessary to consider the positive feedback generated during the process of entering the derating control, including whether positive feedback will occur and the degree of positive feedback generated, etc., to further determine whether derating control of the inverter is required. During the process of derating control of the inverter, the output electrical signal can be restricted according to the target limit value obtained in step 110, so as to effectively suppress the positive feedback during the derating control of the inverter on the basis of restricting the output current according to the difference between the inverter bus voltage and the output voltage to reduce the heating of the inverter inductance and ensure the normal operation of the inverter.

[0086] In some embodiments, when it is determined that the conditions for entering the derating control scenario are met based on the difference degree, it is possible to determine whether derating control of the inverter is required by judging the operating mode of the inverter.

[0087] Among them, the operating mode includes an off-grid operating mode or a grid-connected operating mode.

[0088] If it is in the grid-connected operating mode, it can be approximately considered that no positive feedback will occur, and then the output electrical signal of the inverter can be directly restricted based on the target limit value for derating control.

[0089] If it is in the off-grid operating mode, positive feedback may occur in some operating stages. It is possible to judge whether to perform derating control in combination with the current operating stage of the inverter, and when it is determined that the probability of generating positive feedback is low, restrict the output electrical signal of the inverter based on the limit value for derating control.

[0090] The inventor found during the R & D process that in related technologies, the commonly used derating control method is prone to positive feedback when overloaded in some scenarios, resulting in system shutdown and affecting the use. For example, in the initial state of normal off-grid operation, if the voltage difference on the inverter inductor (the difference between Udc and the output voltage Uan / Ubn / Ucn) is small, the voltage difference derating is not triggered; if the load increases at a certain moment, resulting in the reduction of the inverter output voltage and the increase of the voltage difference between the DC bus voltage and the inverter output voltage; after the voltage difference increases, the voltage difference derating is triggered, and the inverter output current is restricted, that is, the inverter output capacity is limited. At this time, the load remains unchanged, resulting in the further reduction of the inverter output voltage; after the inverter output voltage is further reduced, the voltage difference further increases, and the voltage difference derating further restricts the inverter output, thus forming a positive feedback, resulting in direct shutdown when suddenly overloaded during operation and the problem of inability to start up when starting up (when starting up, the initial inverter output voltage is almost 0, and the voltage difference is very large, resulting in derating to limit the inverter output, and then getting stuck), thus causing the inverter to fail to operate normally.

[0091] In the present application, by detecting whether a large positive feedback will occur when entering the derating control scenario, it is determined whether to enter the derating control scenario, which can reduce the probability that the system cannot operate normally due to the positive feedback generated after entering the derating control, and improve the stability of the system operation.

[0092] According to the control method of the inverter provided by the embodiment of the present application, it is determined whether to meet the condition of entering the derating control scenario through the difference degree, and the inverter is derated in combination with the situation of the positive feedback generated during the derating control process. On the basis of limiting the output current according to the difference between the inverter bus voltage and the output voltage to reduce the heating of the inverter inductance and extend the life of the inverter, the positive feedback during the derating control process of the inverter can be effectively suppressed, ensuring the normal operation of the inverter and meeting the power consumption requirements; and it is applicable to the off-grid operation scenario and has universality.

[0093] In some embodiments, suppressing the positive feedback during the derating control process of the inverter may include:

[0094] Determining whether to enter the derating control scenario based on the difference degree and the operating state of the inverter, and / or performing a delayed derating control on the inverter to suppress the positive feedback during the derating control process of the inverter.

[0095] In this embodiment, the operating state is used to characterize the operating stage during the operation of the inverter system and the relevant conditions of the load connected to the inverter, etc. Among them, the operating stage includes the startup stage of the inverter, the normal operation stage after startup completion, and the overload stage, etc.

[0096] It can be understood that in different operating stages, affected by the specific working conditions, there may be some other factors that cause a large difference between the bus voltage and the output voltage of the inverter. If derating control is performed in these cases, positive feedback may be generated, thus affecting the normal operation in the off-grid state.

[0097] For example, in the startup phase, the output voltage of the inverter approximately rises from 0, so that at the initial stage of startup, the difference between the bus voltage and the output voltage of the inverter is relatively large, which may exceed the derating trigger threshold. If derating control is performed at this time, it will affect the normal startup of the inverter; for another example, in the overload phase, the output voltage of the inverter is pulled down, resulting in the difference between the bus voltage and the output voltage of the inverter exceeding the derating trigger threshold. If derating control is performed at this time, the inverter output voltage will be further pulled down, resulting in a further increase in the difference, and the differential pressure derating will further limit the inverter output, resulting in the shutdown of the inverter. All of the above situations meet the conditions for entering the derating control scenario, but they are all normal phenomena during the normal operation of the inverter. If derating control is performed on the inverter in these situations, in the off-grid operation scenario, positive feedback will be generated, affecting the normal operation of the inverter.

[0098] During the actual execution process, by detecting the current operating stage of the inverter, when the conditions for entering the derating control scenario are met and the inverter is in the corresponding operating stage, the inverter is controlled to enter the derating control scenario; or, when the conditions for entering the derating control scenario are met, a certain delay duration is set to control the inverter to enter the derating control scenario after the delay duration, so as to suppress the positive feedback during the derating control process of the inverter.

[0099] According to the inverter control method provided by the embodiments of the present application, it is determined whether the conditions for entering the derating control scenario are met through the difference degree, and it is determined whether to enter the derating control scenario based on the operating state of the inverter, and / or by performing delay derating control on the inverter, the positive feedback during the derating control process of the inverter can be suppressed, ensuring the normal operation of the inverter and meeting the power consumption requirements.

[0100] In some embodiments, determining to enter the derating control scenario based on the difference degree may include:

[0101] When it is determined that the difference degree is greater than the first threshold and the operating state of the inverter is not the target state, it is determined to enter the derating control scenario.

[0102] In this embodiment, the first threshold is the minimum value of the difference degree for triggering derating control, which can be determined based on user-defined settings or according to historical data or test data. When the difference degree is greater than the first threshold, it is considered that the difference between the bus voltage and the output voltage of the inverter is relatively large, meeting the conditions for entering derating control.

[0103] The target state is the operating state of the inverter in which positive feedback is likely to occur during the derating control process, including the startup phase and the overload phase in the off-grid operation mode, etc.

[0104] When it is determined that the difference degree is greater than the first threshold, it is considered that the condition for entering the derating control is met; if the current operating state of the inverter is not the starting stage or the overload stage, the derating control scenario of the inverter can be carried out according to the target limit value.

[0105] According to the control method of the inverter provided by the embodiments of the present application, it is determined whether to perform derating control through the difference degree and the operating state of the inverter, which can suppress the positive feedback during the derating control process of the inverter and ensure the normal operation of the inverter to meet the power consumption requirements.

[0106] In some embodiments, the starting stage can be determined according to the following steps:

[0107] Since the inverter startup moment, within the first duration, it is determined that the inverter is operating in the starting stage;

[0108] Or,

[0109] Since the inverter startup moment, until the output voltage of the inverter is not less than the startup voltage judgment threshold, it is determined that the inverter is operating in the starting stage.

[0110] In this embodiment, the first duration is used to characterize the duration from the inverter startup moment to the completion of startup and entry into the normal operation state. The first duration can be user-defined or determined through experiments, such as set to 10s or 11s, etc.

[0111] The startup voltage judgment threshold is the minimum output voltage at which the inverter startup is completed.

[0112] In the actual execution process, it can be determined whether the current moment is in the starting stage according to the duration from the inverter startup moment to the current moment and / or the magnitude relationship between the output voltage of the inverter and the startup voltage judgment threshold. If it is in the starting stage, the derating control is not triggered.

[0113] When the inverter starts up from the shutdown state, the output voltage of the inverter starts to rise from almost 0, and the voltage difference from the bus voltage is relatively large during the process. The derating output inverter current limit (i.e., the target limit value) of the voltage difference is relatively small. If the inverter output is limited according to the voltage difference derating current at this time, when starting up with a load, it may be impossible to start up due to insufficient inverter output current capacity, thus affecting the normal operation of the inverter. In the present application, during the startup process of the inverter, it does not respond to the voltage difference derating. Although the ripple current of the inverter inductor will be relatively large during the process and there is a possibility of increased heating of the inverter inductor, since the off-grid startup process is relatively short, generally not exceeding 10s, there will be no thermal risk, as Figure 2 shown.

[0114] When starting up the machine, when the output voltage of the inverter is less than the starting voltage judgment threshold Ustart, it is considered that during the starting process, corresponding to Figure 2 before the moment t1 in it. When in the starting process, derating control is not performed, that is, the output electrical signal of the inverter is not controlled; when the output voltage of the inverter is higher than Ustart, it is determined that the starting is completed, and the differential pressure derating is started to be responded, and the output current limit of the inverter is restricted by the target limit value.

[0115] According to the control method of the inverter provided by the embodiment of the present application, by not triggering derating control in the starting stage of the inverter, the normal starting of the inverter can be guaranteed, and the normal operation of the inverter can be maintained.

[0116] In some embodiments, the overload stage can be determined according to the following steps:

[0117] Since the output current of the inverter is greater than the overload identification threshold, within the second time period, it is determined that the inverter is operating in the overload stage.

[0118] In this embodiment, the second time period is the maximum time period that the inverter can withstand running at a larger output current, which can be set based on the inverter performance, or based on user-defined, and set to a shorter time period, such as set to 8s, 10s or other values, etc.

[0119] The overload identification threshold can be user-defined, and is used to judge whether the output current is too large, so as to judge whether the connected load is overloaded. If the output current of the inverter is greater than the overload identification threshold, it is considered that an overload occurs at the current moment, and the running time can be further combined to detect whether it is in the overload stage.

[0120] It can be understood that in the off-grid operation mode, it is allowed for the inverter to output power exceeding the rated power for a certain period of time. For example, when a heavy load is recognized, the inverter can be supported to operate at a current / rated power exceeding the rated value for a certain period of time, such as 10s; during this process, due to the increased load, the output voltage may be pulled down, resulting in an increased difference between the output voltage and the bus voltage, which may exceed the first threshold. If differential pressure derating control is performed, it may form a positive feedback and cause the inverter to shut down. In the present application, after entering the overload, even if the difference is greater than the first threshold, derating control is still not performed within the second time period; after the second time period, if the difference is still greater than the first threshold, the inverter is derated according to the target limit value.

[0121] Such as Figure 3As shown, the system operates normally before time t1. At time t1, the load increases, the output voltage of the inverter is pulled down, and the output current of the inverter exceeds the overload recognition threshold Ioverload, entering the overload state. The duration of the overload state is detected. When the duration does not exceed the second duration, it is considered that the current is in the overload stage. In the overload stage, the differential derating output is not responded to support stable overload output. When the duration exceeds the second duration, such as when the current time reaches t2 (the duration between t1 and t2 is the second duration), it is considered that the overload stage ends, and the output current of the inverter can be normally limited by differential derating according to the target limit value, and the current limit decreases. At this time, if the load still remains relatively heavy, it indicates that the load exceeds the capacity limit of the inverter, the output voltage is further pulled down, and the target limit value is further reduced. The inverter shuts down to avoid damage to the inverter caused by long-term operation outside the capacity limit range, further maintaining the normal operation of the inverter and extending the life of the inverter.

[0122] During the overload stage, if the load decreases, the output voltage of the inverter rises, and the difference between the output voltage and the bus voltage decreases. If it is less than the first threshold, there is no need to perform derating control anymore, and the inverter can be normally controlled according to the load demand to meet the load demand.

[0123] According to the control method of the inverter provided by the embodiments of the present application, by not performing derating control within the second duration starting from the moment when the output current of the inverter is greater than the overload recognition threshold, it is possible to cope with complex and changeable scenarios such as unstable load and dynamic load changes in the actual application process, reduce the probability of the inverter shutting down caused by the positive feedback of the derating control mis-triggered by short-term load fluctuations, improve the system fault tolerance rate, and ensure the normal power supply of the system. After the second duration, if it is still determined according to the difference that the condition for entering the derating control scenario is met, derating control is performed according to the target limit value, which can avoid damage to the inverter caused by long-term operation outside the capacity limit range, further maintain the normal operation of the inverter, and extend the life of the inverter.

[0124] In some embodiments, step 120 may include:

[0125] When it is determined based on the difference that the derating control scenario is entered, the output electrical signal of the inverter is delayed and limited based on the target limit value.

[0126] In this embodiment, by delaying and limiting the output limit number of the inverter, the time for the inverter to enter the derating control can be appropriately delayed, so that the inverter can operate at a relatively large output current for a certain duration within the tolerable range to cope with the short-term voltage fluctuations of the output voltage caused by short-term load fluctuations or inverter startup during the actual operation process, improve the robustness, and ensure the normal operation and power supply of the inverter.

[0127] In some embodiments, delaying and limiting the output electrical signal of the inverter based on a target limit value may include:

[0128] After the target delay duration and when the difference degree is greater than a first threshold value, limit the output electrical signal of the inverter based on the target limit value.

[0129] In this embodiment, the target delay duration can be set according to the performance parameters of the inverter, such as the maximum tolerance, or determined through experiments, or based on user-defined settings. This application does not make any limitations here. Within the target delay duration, the inverter operates with a relatively large output current, and it can be approximately considered that there will be no impact on the system, thus damaging the system.

[0130] For example, when the difference degree is greater than the first threshold value, it is considered that the condition for entering the derating control is met. On this basis, the response to the differential pressure derating is increased by a delay time. For example, after the target delay duration, the derating control is performed according to the target limit value, so as to ensure that during operation, when the output voltage decreases due to transient heavy loads, etc., the system can operate normally and avoid the formation of positive feedback shutdown after the transient heavy loads, etc., pull down the output voltage.

[0131] As Figure 4 shown, before time t1, the system operates normally. At time t1, the load suddenly increases, the output current of the inverter increases, and the output voltage of the inverter decreases, resulting in an increase in the difference degree. If the difference degree is greater than the first threshold value, it is considered that the condition for entering the derating control is met. Since the target delay duration Δt is set, no derating control needs to be performed between time t1 and time t3, that is, the inverter output current limit does not decrease;

[0132] During this process, if time t2 is reached and the load decreases, the output current of the inverter decreases, causing the output voltage of the inverter to rise. Even if the difference degree is still greater than the first threshold value at this moment, since it is still within the differential pressure derating delay time, the output electrical signal of the inverter is still not limited, and the difference degree shows a decreasing trend. In a short time, this difference degree can quickly recover within the first threshold value, and the impact of this short-time large current on the inverter can be approximately ignored. Without damaging the inverter, it can also ensure that the transient increase in load does not cause positive feedback shutdown, improving the robustness of the system.

[0133] If after time t3, the load still does not decrease and the difference degree between the output voltage of the inverter and the bus voltage is still large, then normal derating control is performed on the inverter according to the target limit value to reduce the current ripple on the inverter inductor, reduce heat generation, reduce the risk of damage to the inverter inductor or other devices caused by excessive ripple heat on the inverter inductor, extend the service life of the inverter, and ensure the safe operation of the system.

[0134] In some embodiments, delaying and limiting the output electrical signal of the inverter based on a target limit value may include:

[0135] Performing low-pass filtering on the target limit value, and limiting the output electrical signal of the inverter based on the target limit value after low-pass filtering.

[0136] In this embodiment, low-pass filtering is used to filter out the lower values of the target limit value, and the effect of delay derating control can also be achieved. The specific parameters of the low-pass filtering can be set according to the target limit value and the required delay duration, etc.

[0137] According to the inverter control method provided by the embodiments of the present application, by delaying and limiting the output electrical signal of the inverter based on the target limit value when it is determined that the derating control scenario is entered based on the degree of difference, it is possible to ensure that the load increase during transient conditions does not cause positive feedback shutdown without damaging the inverter, improve the robustness of the system, and ensure the normal power supply of the system.

[0138] For the inverter control method provided by the embodiments of the present application, the execution subject may be a control device of the inverter. In the embodiments of the present application, taking the control device of the inverter executing the inverter control method as an example, the control device of the inverter provided by the embodiments of the present application is described.

[0139] The embodiments of the present application further provide a control device for an inverter.

[0140] As Figure 5 shown, the control device of the inverter includes: a first processing module 510 and a second processing module 520.

[0141] The first processing module 510 is configured to obtain the degree of difference between the bus voltage and the output voltage of the inverter, and the target limit value corresponding to the output electrical signal of the inverter in an off-grid scenario;

[0142] The second processing module 520 is configured to limit the output electrical signal of the inverter based on the target limit value when it is determined that the derating control scenario is entered based on the degree of difference, so as to suppress the positive feedback during the derating control of the inverter.

[0143] According to the control device of the inverter provided by the embodiments of the present application, it is possible to determine whether to enter the derating control scenario through the degree of difference, and perform derating control on the inverter in combination with the positive feedback generated during the derating control process. On the basis of reducing the heating of the inverter inductance by limiting the output current according to the difference between the inverter bus voltage and the output voltage, effectively suppressing the positive feedback during the derating control process of the inverter, ensuring the normal operation of the inverter, meeting the power consumption requirements; and applicable to off-grid operation scenarios, with universality.

[0144] In some embodiments, the device may further include a third processing module for:

[0145] When it is determined that the difference degree is greater than the first threshold and the operating state of the inverter is not the target state, determine to enter the derating control scenario; the target state includes the startup stage or the overload stage.

[0146] In some embodiments, the third processing module may also be used for:

[0147] Determine that the inverter operates in the startup stage within the first time period since the inverter is powered on.

[0148] Or,

[0149] Determine that the inverter operates in the startup stage from the moment the inverter is powered on until the output voltage of the inverter is not less than the starting voltage judgment threshold.

[0150] In some embodiments, the third processing module may also be used for:

[0151] Determine that the inverter operates in the overload stage within the second time period since the output current of the inverter is greater than the overload recognition threshold.

[0152] In some embodiments, the second processing module 520 may also be used for:

[0153] When it is determined to enter the derating control scenario based on the difference degree, delay and limit the output electrical signal of the inverter based on the target limit value.

[0154] In some embodiments, the second processing module 520 may also be used for:

[0155] After the target delay duration and when the difference degree is greater than the first threshold, limit the output electrical signal of the inverter based on the target limit value.

[0156] In some embodiments, the second processing module 520 may also be used for:

[0157] Perform low-pass filtering on the target limit value, and limit the output electrical signal of the inverter based on the target limit value after low-pass filtering.

[0158] In some embodiments, the first processing module 510 may also be used for:

[0159] Obtain the target limit value of the output electrical signal corresponding to the difference degree.

[0160] In some embodiments, the first processing module 510 may also be used for:

[0161] Query the preset association table to obtain at least one candidate limit value that matches the difference degree; the preset association table includes multiple candidate difference degrees and candidate limit values corresponding to the candidate difference degrees;

[0162] Determine the target limit value based on at least one candidate limit value.

[0163] In some embodiments, the first processing module 510 may also be used for:

[0164] Obtain the target limit value that matches the actual temperature and the difference degree according to the actual temperature and the difference degree of the inverter.

[0165] In some embodiments, the second processing module 520 may also be used for:

[0166] Determine whether to enter the derating control scenario based on the difference degree and the operating state of the inverter, and / or perform a time-delay derating control on the inverter to suppress the positive feedback during the derating control process of the inverter.

[0167] The control device of the inverter in the embodiments of the present application may be an electronic device or a component in an electronic device, such as an integrated circuit or a chip. The electronic device may be a terminal or other devices other than the terminal. Exemplarily, the electronic device may be a mobile phone, a tablet computer, a laptop computer, a handheld computer, a vehicle-mounted electronic device, a Mobile Internet Device (MID), an augmented reality (AR) / virtual reality (VR) device, a robot, a wearable device, an ultra-mobile personal computer (UMPC), a netbook or a personal digital assistant (PDA), etc., and may also be a server, a Network Attached Storage (NAS), a personal computer (PC), a television (TV), a teller machine or a self-service machine, etc. The embodiments of the present application do not make specific limitations.

[0168] The control device of the inverter in the embodiments of the present application may be a device with an operating system. The operating system may be an Android operating system, an IOS operating system, or other possible operating systems. The embodiments of the present application do not make specific limitations.

[0169] The control device of the inverter provided in the embodiments of the present application can achieve Figures 1 to 4The various processes implemented by the method embodiments are not described herein again to avoid repetition.

[0170] The embodiments of the present application further provide an inverter system.

[0171] The inverter system includes an inverter, and the inverter operates based on the control method of the inverter described in any of the above embodiments.

[0172] According to the inverter system provided by the embodiments of the present application, it is determined whether to enter the derating control scenario through the difference degree, and the inverter is derated by combining the positive feedback generated during the process of entering the derating control. On the basis of limiting the output current according to the difference between the inverter bus voltage and the output voltage to reduce the heating of the inverter inductance and extend the life of the inverter, the positive feedback during the derating control of the inverter can be effectively suppressed, ensuring the normal operation of the inverter and meeting the power consumption requirements; and it is applicable to the off-grid operation scenario and has universality.

[0173] In some embodiments, as Figure 6 shown, the embodiments of the present application further provide an electronic device 600, including a processor 601, a memory 602, and a computer program stored on the memory 602 and executable on the processor 601. When the program is executed by the processor 601, it implements the various processes of the method embodiments of the above-mentioned inverter control method and can achieve the same technical effects. To avoid repetition, it is not described herein again.

[0174] It should be noted that the electronic devices in the embodiments of the present application include the above-mentioned mobile electronic devices and non-mobile electronic devices.

[0175] The embodiments of the present application further provide a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the various processes of the method embodiments of the above-mentioned inverter control method and can achieve the same technical effects. To avoid repetition, it is not described herein again.

[0176] Wherein, the processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory ROM, random access memory RAM, magnetic disks, or optical disks, etc.

[0177] The embodiments of the present application further provide a computer program product, including a computer program, which implements the above-mentioned inverter control method when executed by a processor.

[0178] Among them, the processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory ROM, random access memory RAM, magnetic disks, or optical discs, etc.

[0179] Another embodiment of the present application provides a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor. The processor is used to run programs or instructions to implement each process of the above-described embodiment of the inverter control method, and can achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0180] It should be understood that the chip mentioned in the embodiments of the present application may also be referred to as a system-on-chip, system chip, chip system, or system-on-chip, etc.

[0181] It should be noted that in this article, the term "including", "comprising", or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article, or device. Without further limitation, the element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article, or device including that element. In addition, it should be pointed out that the methods and devices in the embodiments of the present application are not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in a reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. Additionally, the features described with reference to certain examples may be combined in other examples.

[0182] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-described embodiment methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases, the former is a better implementation method. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, can be embodied in the form of a computer software product. The computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disc), and includes several instructions to enable a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present application.

[0183] The embodiments of the present application have been described above in conjunction with the accompanying drawings. However, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all of them fall within the protection scope of the present application.

[0184] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0185] Although the embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present application. The scope of the present application is defined by the claims and their equivalents.

Claims

1. A control method for an inverter, characterized in that: include: In an off-grid scenario, obtaining a difference between a bus voltage and an output voltage of the inverter, and a target limit value corresponding to an output electrical signal of the inverter; In the case where it is determined to enter a derating control scenario based on the difference, the output electrical signal of the inverter is limited based on the target limit value to suppress positive feedback of the inverter during the derating control process.

2. The inverter control method according to claim 1, characterized in that: The determining, based on the difference, to enter a derating control scenario includes: When it is determined that the difference is greater than a first threshold and the inverter operation state is not a target state, it is determined to enter the derating control scenario; the target state includes a startup stage or an overload stage.

3. The control method of the inverter according to claim 2, characterized in that: The startup phase is determined according to the following steps: From the moment the inverter is turned on, within a first time period, determining that the inverter is operating in the startup phase; or, From the moment the inverter is turned on until the output voltage of the inverter is not less than the startup voltage judgment threshold, it is determined that the inverter is operating in the startup phase.

4. The control method of the inverter according to claim 2, characterized in that: The overload stage is determined according to the following steps: From the moment when the output current of the inverter is greater than the overload identification threshold, within a second time period, it is determined that the inverter is operating in the overload stage.

5. The inverter control method according to any one of claims 1 to 4, characterized in that: In the case where it is determined to enter a derating control scenario based on the difference, limiting the output electrical signal of the inverter based on the target limit value includes: In a case where it is determined to enter the derating control scenario based on the difference, delay limitation is performed on the output electrical signal of the inverter based on the target limit value.

6. The control method of the inverter according to claim 5, characterized in that: The delay limiting of the output electrical signal of the inverter based on the target limit value includes: After the target delay time, and when the difference is greater than a first threshold, the output electrical signal of the inverter is limited based on the target limit value.

7. The control method of the inverter according to claim 5, characterized in that: The delay limiting of the output electrical signal of the inverter based on the target limit value includes: The target limit value is subjected to low-pass filtering, and the output electrical signal of the inverter is limited based on the target limit value subjected to the low-pass filtering.

8. The inverter control method according to any one of claims 1 to 4, characterized in that: Obtaining a target limit value corresponding to an output electrical signal of the inverter includes: A target limit value of the output electrical signal corresponding to the difference is obtained.

9. The inverter control method according to claim 8, characterized in that: The obtaining of a target limit value of the output electrical signal corresponding to the difference comprises: Querying a preset association table to obtain at least one candidate limit value matching the difference; the preset association table includes a plurality of candidate differences and candidate limit values ​​corresponding to the candidate differences; Based on the at least one candidate limit value, the target limit value is determined.

10. The inverter control method according to claim 8, characterized in that: The obtaining of a target limit value of the output electrical signal corresponding to the difference comprises: According to the actual temperature of the inverter and the difference, a target limit value matching the actual temperature and the difference is acquired.

11. The inverter control method according to claim 1, characterized in that: The step of suppressing positive feedback of the inverter during derating control includes: By determining whether to enter a derating control scenario based on the difference and the operating state of the inverter, and / or by performing delayed derating control on the inverter, positive feedback of the inverter during derating control is suppressed.

12. A control device for an inverter, characterized in that: include: A first processing module is used to obtain the difference between the bus voltage and the output voltage of the inverter and the target limit value corresponding to the output electrical signal of the inverter in an off-grid scenario; The second processing module is used to limit the output electrical signal of the inverter based on the target limit value when it is determined to enter the derating control scenario based on the difference, so as to suppress positive feedback of the inverter during the derating control process.

13. An inverter system, characterized in that: include: An inverter, wherein the inverter operates based on the inverter control method according to any one of claims 1 to 11.

14. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the control method of the inverter as described in any one of claims 1 to 11 is implemented.

15. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the control method of the inverter as claimed in any one of claims 1 to 11 is implemented.

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