Methods for detecting PV common-mode inductor failure in energy storage inverters, storage media, and energy storage inverters

Abstract

This invention proposes a method for detecting the failure of a PV common-mode inductor in an energy storage inverter, a storage medium, and an energy storage inverter. The method includes: acquiring the on / off state of the electronic switches of each PV input branch; determining whether the on / off state of the electronic switches of each PV input branch meets a preset trigger condition, wherein the trigger condition is: only one PV branch in the PV branch group corresponding to the common-mode inductor to be detected is in the active state, and each PV branch corresponding to each non-detected common-mode inductor is in the open state; when the trigger condition is met, detecting the current in any PV branch that is in the open state corresponding to any non-detected common-mode inductor, and calculating the current amplitude; if the current amplitude is greater than a preset threshold, it is determined that the common-mode inductor to be detected has a failure risk. This invention detects cross-branch current crosstalk caused by inductor failure in a multi-PV shared common-mode inductor structure online by detecting the current amplitude, and determines whether the inductor has failed.

Description

Technical Field

[0001] This invention relates to the field of energy storage inverter technology, and in particular to a method for detecting PV common-mode inductor failure in an energy storage inverter, a storage medium, and an energy storage inverter. Background Technology

[0002] To accommodate the installation requirements of photovoltaic modules facing different directions (such as south-facing, east-facing, and west-facing roofs), residential three-phase energy storage inverters are typically designed with three or four independent PV input (MPPT) channels. To achieve high power density within limited residential installation space while effectively suppressing common-mode interference current (leakage current) generated on the PV side to ground, current technologies generally employ a topology where multiple PV inputs share a single common-mode inductor. For example, in a four-PV input residential inverter, PV1 and PV2 are typically grouped together, sharing the common-mode inductor L1; PV3 and PV4 are grouped together, sharing the common-mode inductor L2. This design utilizes the magnetic coupling characteristics of the common-mode inductor, presenting low impedance to differential-mode current (i.e., generation current) and high impedance to common-mode interference current during normal operation, thus meeting electromagnetic compatibility (EMC) standards and preventing frequent inverter shutdowns due to excessive leakage current.

[0003] However, current sampling and protection logic in existing technologies typically only focuses on whether the current of a single PV circuit exceeds the hardware overcurrent threshold or monitors whether the total leakage current exceeds the limit, neglecting the logical interlocking relationship of current flow between different PV branches. In a structure where multiple PV circuits share a common-mode inductor, each PV input should be a physically independent current loop (except for the common-mode path). When the common-mode inductor fails prematurely due to core saturation, partial short circuit in the winding, or insulation degradation, its internal magnetic circuit or circuit abnormalities may generate unexpected current coupling paths. For example, the current in one set of PV branches may couple to another set of PV branches that should be electrically isolated through the failed common-mode inductor. The amplitude of this cross-branch current crosstalk is usually small and has not yet reached the hardware overcurrent protection threshold, so it is difficult to detect by traditional overcurrent protection circuits. If operated for a long time, this latent fault may lead to safety hazards such as excessive leakage current, live equipment casing, or even electrical fires.

[0004] Therefore, how to detect cross-branch current crosstalk caused by inductor failure in a multi-channel PV shared common-mode inductor structure online, so as to achieve an accurate assessment of the health status of the common-mode inductor, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This invention proposes a method for detecting the failure of the PV common-mode inductor in an energy storage inverter. The PV side of the energy storage inverter includes multiple common-mode inductors, and each common-mode inductor corresponds to at least one PV input branch. The method for detecting the failure of the PV common-mode inductor in the energy storage inverter includes: Obtain the on / off status of the electronic switches in each PV input branch; Determine whether the on / off state of the electronic switches of each PV input branch meets the preset triggering conditions. The triggering conditions are: only one PV branch in the PV branch group corresponding to the common-mode inductor to be detected is in the on state, and each PV branch corresponding to each non-detected common-mode inductor is in the off state; wherein, the common-mode inductor includes: the common-mode inductor to be detected and the non-detected common-mode inductor. When the triggering condition is met, detect the current of any PV branch that is in an open state corresponding to any non-detected common-mode inductor, and calculate the current amplitude. If the current amplitude is greater than a preset threshold, it is determined that the common-mode inductor to be tested is at risk of failure.

[0006] Optionally, when the trigger condition is met, detecting the current in any PV branch that is in an open state corresponding to any non-detected common-mode inductor and calculating the current amplitude includes: When the triggering condition is met, the current of any PV branch that is in the open state corresponding to any non-detected common mode inductor is detected N times, and the current amplitude of each detection is calculated. Accordingly, if the current amplitude is greater than a preset threshold, it is determined that the common-mode inductor under test has a risk of failure, including: When the current amplitude obtained from N consecutive samplings is greater than the preset threshold, it is determined that the common-mode inductor to be detected has a risk of failure, where N is an integer greater than or equal to 2.

[0007] Optionally, after detecting the current of any PV branch in the open state corresponding to any non-detected common-mode inductor N times and calculating the current amplitude for each detection when the trigger condition is met, the method further includes: Iterate through the fault count values ​​where the current amplitude is greater than the preset threshold; If the fault count value is equal to N, it is determined that the common mode inductor to be tested is at risk of failure. If the current amplitude is less than the preset threshold, the fault count value is reset to zero.

[0008] Optionally, after determining that the common-mode inductor to be tested has a failure risk, the method further includes: Obtain the identification information of the common-mode inductor to be detected; Fault information is generated and output based on the identification information.

[0009] Optionally, after determining that the common-mode inductor to be tested has a failure risk, the method further includes: Control the shutdown of the energy storage inverter or limit its power output.

[0010] Optionally, the preset threshold is greater than the amplitude of the induced noise current when the branch is disconnected under normal operating conditions, and less than the amplitude of the normal power generation current.

[0011] The present invention also proposes a storage medium storing a PV common-mode inductor failure detection program for an energy storage inverter, wherein the PV common-mode inductor failure detection program for an energy storage inverter implements the steps of the PV common-mode inductor failure detection method for an energy storage inverter when executed by a processor.

[0012] The present invention also proposes an energy storage inverter, the energy storage inverter comprising: Multiple common-mode inductors; Multiple PV input branches, each of the aforementioned common-mode inductors corresponds to at least one PV input branch; An electronic switch is installed in each PV input branch; A current detection sensor is installed in each PV input branch; The controller is connected to the electronic switches and current detection sensors in each PV input branch; The controller is configured to perform the steps of the energy storage inverter PV common mode inductor failure detection method.

[0013] Optionally, the electronic switch is a relay or a semiconductor switch.

[0014] This invention proposes a method for detecting the failure of a PV common-mode inductor in an energy storage inverter, a storage medium, and an energy storage inverter. The method includes: acquiring the on / off state of the electronic switches of each PV input branch; determining whether the on / off state of the electronic switches of each PV input branch meets a preset trigger condition, wherein the trigger condition is: only one PV branch in the PV branch group corresponding to the common-mode inductor to be detected is in the active state, and each PV branch corresponding to each non-detected common-mode inductor is in the disconnected state; when the trigger condition is met, detecting the current of any PV branch in the disconnected state corresponding to any non-detected common-mode inductor, and calculating the current amplitude; if the current amplitude is greater than a preset threshold, then determining that the common-mode inductor to be detected has a failure risk. This invention, by detecting the PV branches corresponding to non-detected inductors under trigger conditions, and based on the detected current amplitude, online detects cross-branch current crosstalk caused by inductor failure in a multi-PV shared common-mode inductor structure, and determines whether the inductor to be detected has a failure risk. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the first step of the first embodiment of the PV common-mode inductor failure detection method for energy storage inverters of the present invention; Figure 2 This is a schematic diagram of an example four-channel PV input inverter structure, representing the first embodiment of the PV common-mode inductor failure detection method for energy storage inverters of the present invention. Figure 3 This is a schematic diagram of the second step of the first embodiment of the PV common-mode inductor failure detection method for energy storage inverters of the present invention.

[0017] Explanation of icon numbers: L1, first common-mode inductor; L2, second common-mode inductor; L3, third inductor; L4, fourth inductor; L5, fifth inductor; L6, sixth inductor; D1 to D4, first to fourth diodes; S1 to S4, first to fourth switches.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0021] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0023] This invention proposes a method for detecting the failure of the PV common-mode inductor in an energy storage inverter, which is applied to an energy storage inverter. The PV side of the energy storage inverter includes multiple common-mode inductors, and each common-mode inductor corresponds to at least one PV input branch. like Figure 1 As shown, in the first embodiment of the present invention, the method for detecting the failure of the PV common-mode inductor of the energy storage inverter includes: The method for detecting the failure of the PV common-mode inductor in the energy storage inverter includes: Obtain the on / off status of the electronic switches in each PV input branch; Determine whether the on / off state of the electronic switches of each PV input branch meets the preset triggering conditions. The triggering conditions are: only one PV branch in the PV branch group corresponding to the common-mode inductor to be detected is in the on state, and each PV branch corresponding to each non-detected common-mode inductor is in the off state; wherein, the common-mode inductor includes: the common-mode inductor to be detected and the non-detected common-mode inductor. When the triggering condition is met, detect the current of any PV branch that is in an open state corresponding to any non-detected common-mode inductor, and calculate the current amplitude. If the current amplitude is greater than a preset threshold, it is determined that the common-mode inductor to be tested is at risk of failure.

[0024] It should be explained that this method is applied to energy storage inverters, particularly residential three-phase energy storage inverters. On the PV side of this inverter, multiple common-mode inductors are installed, each corresponding to at least one PV input branch. For example, as... Figure 2 As shown, in a common four-channel PV input inverter, two common-mode inductors can be configured. The first common-mode inductor corresponds to the PV1 and PV2 inputs, and the second common-mode inductor corresponds to the PV3 and PV4 inputs. It should be noted that the technical solution of this invention is not limited to two common-mode inductors or two inputs per group; it is applicable to any number of common-mode inductors and any number (one or more) of PV input branches per group. In this invention, a "PV branch" refers to a DC circuit path connecting the photovoltaic module and inputting it to the inverter. Each PV input branch typically includes a positive bus and a negative bus, connected to the positive and negative output terminals of the photovoltaic module, respectively. Common-mode inductors are classified according to whether their validity is determined in this test, and can be divided into common-mode inductors to be tested and non-tested common-mode inductors; this invention is used to detect and determine whether the common-mode inductor to be tested has a risk of failure.

[0025] like Figure 2 As shown, the third inductor L3 is located in the PV1 branch and is connected to the first diode D1 and the first switch S1; the fourth inductor L4 is located in the PV2 branch and is connected to the second diode D2 and the second switch S2; the fifth inductor L5 is located in the PV3 branch and is connected to the third diode D3 and the third switch S3; the sixth inductor L6 is located in the PV4 branch and is connected to the fourth diode D4 and the fourth switch S4. During inverter operation, the control system acquires the on / off status of the electronic switches of each PV input branch in real time. These electronic switches can be relays or semiconductor switches, such as MOSFETs and IGBTs, used to independently control whether each PV input is connected to the inverter's main circuit. By reading the switch status signals reported by the underlying driver, the control system can determine which PV branches are currently in operation and which are in the off state.

[0026] The core of this invention lies in utilizing the normal electrical isolation characteristics between multiple PV input branches to construct a detection criterion based on the logical mutual exclusion of switch states and current flow directions. Specifically, when only one PV branch in the PV branch group corresponding to a certain common-mode inductor to be detected is in the active state, while every PV branch corresponding to all other non-detection common-mode inductors is in the open state, the system enters the detection trigger condition. Under this condition, theoretically, since all PV branches corresponding to non-detection common-mode inductors are open, there should be no current flowing in their branches. However, if the common-mode inductor to be detected fails, such as core saturation, partial short circuit in the winding, or insulation degradation, the common-mode current in the active PV branch may couple through the failed common-mode inductor to one of the disconnected branches corresponding to the non-detection common-mode inductor, thereby generating abnormal current in that disconnected branch.

[0027] It is important to note that even when the electronic switch is off, a parasitic path still exists between the PV input terminal and the protective earth (PE) through the inverter's internal EMI filter capacitor (commonly known as the Y capacitor). Under normal operating conditions, due to the magnetic isolation effect of the common-mode inductor, only a weak induced noise current (typically less than 1 mA) exists in this parasitic path. When the common-mode inductor to be detected fails, its internal magnetic coupling characteristics are disrupted, potentially forming an unexpected current path across the windings. In this case, the common-mode current in the operating branch can be coupled to the input terminal of another group (the disconnected branch group) through the failed common-mode inductor, and forms a closed loop through the Y capacitor of the disconnected branch, the protective earth, and the Y capacitor of the operating branch. Therefore, even when the electronic switch is off, an abnormal current with a significantly increased amplitude can still be detected in the disconnected branch. This invention utilizes this physical phenomenon to infer the failure of the common-mode inductor by detecting this abnormal current.

[0028] When the above triggering conditions are met, the system detects the current in any PV branch that is in an open state corresponding to any non-detection common-mode inductor, and calculates the amplitude of that current. "Any branch" means that any one of the multiple open branches corresponding to the non-detection common-mode inductor can be selected for detection, such as selecting a pre-specified fixed branch, or selecting different branches in turn. This invention does not limit this, as long as it can reflect the current status in the branch corresponding to the non-detection common-mode inductor.

[0029] The system then compares the calculated current amplitude with a preset threshold. This preset threshold is a pre-defined current value that should be greater than the amplitude of the induced noise current present in the disconnected branch under normal operating conditions (typically in the sub-milliampere level), while being much smaller than the amplitude of the normal generating current (typically in the ampere level). As a preferred example, this threshold can be set between 3 mA and 30 mA. The specific value of the threshold can be calibrated according to the actual circuit parameters of the inverter, the capacitance value of the Y capacitor, and electromagnetic compatibility requirements. This invention does not limit its specific value, as long as it meets the functional requirement of "greater than normal noise and less than normal generating current".

[0030] If the detected current amplitude is less than or equal to the preset threshold, it indicates that the common-mode inductor under test has good isolation performance against cross-branch current and has not experienced significant failure. If the detected current amplitude is greater than the preset threshold, it indicates that an abnormal current has appeared in the disconnected branch that should theoretically be isolated. This abnormal current is due to cross-branch current crosstalk caused by the failure of the common-mode inductor under test. Therefore, it can be determined that the common-mode inductor under test has a failure risk.

[0031] To more clearly illustrate the detection logic of this invention, as follows: Figure 2As shown, the following description uses an inverter containing two common-mode inductors as an example. Assume the inverter includes a first common-mode inductor and a second common-mode inductor, where the first common-mode inductor corresponds to branches PV1 and PV2, and the second common-mode inductor corresponds to branches PV3 and PV4. Branch PV1 corresponds to switch S1, branch PV2 corresponds to switch S2, branch PV3 corresponds to switch S3, and branch PV4 corresponds to switch S4. When the first common-mode inductor is the common-mode inductor to be detected, the triggering condition is: only one of PV1 and PV2 (e.g., PV1) is in the active state, and both PV3 and PV4 are in the off state. At this time, the system collects the current amplitude of either PV3 or PV4 (e.g., PV4). If this current amplitude is greater than a preset threshold, it is determined that the first common-mode inductor has a failure risk. Similarly, when the second common-mode inductor is the common-mode inductor to be tested, the triggering condition is: only one of PV3 and PV4 is in the active state, and PV1 and PV2 are both in the inactive state. The system collects the current amplitude of either PV1 or PV2 for judgment. For inverters containing more than three common-mode inductors, each common-mode inductor can be used as the common-mode inductor to be tested, and all other common-mode inductors can be used as non-test common-mode inductors. The above detection steps are executed sequentially to achieve the health status assessment of each common-mode inductor.

[0032] After determining that the common-mode inductor under test is at risk of failure, the system can execute subsequent fault response actions. For example, it can generate a fault flag and output fault information containing the identifier of the common-mode inductor under test through the communication interface to notify the user or the operation and maintenance platform. At the same time, the system can also perform protection actions, such as controlling the inverter to shut down or limiting power output, to prevent the fault from worsening and avoid causing secondary disasters.

[0033] The method provided by this invention is implemented entirely through software algorithms, requiring no additional hardware detection circuits or sensors. It can be accomplished solely using the inverter's existing current sampling circuit (such as an ADC module) and switch status monitoring function. This method can detect early failure of the common-mode inductor online and in real time, filling the gap in existing technologies that lack cross-branch current crosstalk detection capabilities in multi-PV shared common-mode inductor structures. It has significant practical value and economic benefits.

[0034] Based on the foregoing embodiments, in order to further improve the reliability of detection and avoid false alarms caused by transient electromagnetic interference, sampling noise or brief common-mode current fluctuations, the present invention also provides a preferred embodiment, namely, introducing a delayed confirmation mechanism.

[0035] In one example, when the trigger condition is met, detecting the current in any PV branch that is in an open state corresponding to any non-detected common-mode inductor and calculating the current amplitude includes: When the triggering condition is met, the current of any PV branch that is in the open state corresponding to any non-detected common mode inductor is detected N times, and the current amplitude of each detection is calculated. Accordingly, if the current amplitude is greater than a preset threshold, it is determined that the common-mode inductor under test has a risk of failure, including: When the current amplitude obtained from N consecutive samplings is greater than the preset threshold, it is determined that the common-mode inductor to be detected has a risk of failure, where N is an integer greater than or equal to 2.

[0036] Specifically, when the system detects that the trigger condition is met, it does not rely solely on the current amplitude obtained from a single sampling, but rather performs multiple consecutive samplings and judgments. Under the trigger condition, the system continuously monitors the current in any PV branch that is in an open state corresponding to any non-detection common-mode inductor, and calculates the current amplitude obtained from each sampling. The system continuously executes the above sampling and calculation process, accumulating N sampling results, where N is an integer greater than or equal to 2. Those skilled in the art can reasonably choose the specific value of N according to the actual operating environment and anti-interference requirements of the inverter; for example, N can be 3, 4, or 5.

[0037] The system only determines that the common-mode inductor under test is at risk of failure if the current amplitude obtained from N consecutive samplings is greater than the preset threshold. If the current amplitude obtained from any sampling during the continuous sampling process is less than or equal to the preset threshold, the current detection cycle is terminated, the system does not consider it a failure, and the sampling count for the next detection cycle is restarted.

[0038] To facilitate understanding and implementation of this delayed confirmation mechanism by those skilled in the art, a specific implementation method is provided below. The system can set a fault counter, with an initial value of zero. Each time a current amplitude greater than a preset threshold is detected, the fault counter increments by 1; if the detected current amplitude is less than or equal to the preset threshold, the fault counter is reset to zero. When the value of the fault counter reaches or exceeds a preset consecutive count threshold N, the system determines that the common-mode inductor under test does indeed have a failure risk and generates a fault flag. This implementation method is simple and reliable, requiring no complex timing control, and can be completed using counting logic in software.

[0039] It should be noted that the "N consecutive samplings" mentioned in this invention refers to the situation where, in an uninterrupted sampling sequence, all N adjacent sampling results satisfy the threshold condition. The sampling interval can be set according to the inverter's current sampling frequency and actual response requirements. For example, it can be set to sample once per power frequency cycle, or sample at fixed time intervals (such as 10 milliseconds, 100 milliseconds, etc.). This invention does not impose specific limitations on this, as long as it can ensure that the judgment of the number of consecutive samplings is completed within a reasonable time window.

[0040] The technical advantages of introducing a delayed confirmation mechanism are twofold: First, it effectively filters out instantaneous current spikes caused by external electromagnetic interference, transient switching operations, or ADC sampling noise, avoiding misjudging these brief, non-persistent anomalies as common-mode inductor failures, thus reducing the system's false alarm rate. Second, this mechanism maintains both detection sensitivity and accuracy, because the cross-branch current crosstalk caused by genuine common-mode inductor failure is usually a continuous and stable abnormal current that consistently exceeds the threshold in multiple consecutive samples and does not disappear on its own within a short period. Therefore, through N consecutive threshold-exceeding confirmations, the system can reliably distinguish between genuine device failures and transient environmental interference, achieving a good balance between detection robustness and sensitivity.

[0041] In practical applications, those skilled in the art can adjust the value of N according to the severity of the electromagnetic environment and the system's tolerance to false alarms. For user scenarios with complex electromagnetic environments, a larger N value (e.g., 5 times) can be selected to obtain higher anti-interference capability; for scenarios requiring fast response, a smaller N value (e.g., 2 times or 3 times) can be selected to shorten the detection time. This flexibility allows the present invention to adapt to different application needs.

[0042] In one example, such as Figure 3 As shown, when the triggering condition is met, the current of any PV branch corresponding to any non-detected common-mode inductor that is in an open state is detected N times, and the current amplitude of each detection is calculated. The process also includes: Iterate through the fault count values ​​where the current amplitude is greater than the preset threshold; If the fault count value is equal to N, it is determined that the common mode inductor to be tested is at risk of failure. If the current amplitude is less than the preset threshold, the fault count value is reset to zero.

[0043] As is easily understood, after the trigger condition is met, the system begins sampling and calculating the amplitude of the current in the designated disconnected branch. After each sampling, the system compares the obtained current amplitude with a preset threshold. Based on the comparison result, the system performs the corresponding operation in one of the following three cases.

[0044] The first scenario: When the detected current amplitude exceeds the preset threshold, it indicates that an abnormal current has been detected at the current sampling time. In this case, the system increments the current value of the fault counter by 1. For example, if the initial value of the fault counter is 0, it becomes 1 after the first time the threshold is exceeded; if there are previous records of consecutive threshold exceedances, the counter value is incremented based on the original count.

[0045] The second scenario: After incrementing the fault counter, the system checks if the current value of the fault counter is greater than or equal to a preset consecutive count threshold N (N is an integer greater than or equal to 2, such as 3, 4, or 5). If the fault count reaches N, it indicates that abnormal current exceeding the threshold has been detected in N consecutive samples, and the system determines that the common-mode inductor under test does indeed have a failure risk. Afterward, the system can generate a fault flag, output fault information, or execute corresponding protection actions.

[0046] The third scenario: If the current amplitude detected is less than or equal to the preset threshold, it indicates that no abnormal current was detected at the current sampling time. In this case, the system will reset the fault counter to zero. This means that if any sampling result does not exceed the threshold, the "continuous threshold exceeding" sequence will be interrupted, and the previously accumulated count will be reset to zero, requiring a restart of the counting process.

[0047] It is important to note that the logic for resetting the fault counter is crucial. It ensures that only N consecutive instances of exceeding the threshold can trigger a fault determination. If the abnormal current is intermittent (e.g., due to occasional external interference), the counter will be reset to zero during the next normal sampling after each interference disappears, preventing it from accumulating to N instances and effectively avoiding false alarms. Conversely, if the common-mode inductor does indeed fail, causing persistent cross-branch current crosstalk, each sampling will yield a current amplitude exceeding the threshold, and the counter will increment sequentially until it reaches N, thus accurately triggering the fault. The fault counter method described in this example is a specific and preferred implementation of a delayed confirmation mechanism. It achieves accurate judgment of N consecutive threshold exceedances through simple increment, reset, and comparison operations. The logic is clear, the code implementation is simple, and it has strong anti-interference capabilities. Those skilled in the art should understand that other equivalent delayed confirmation methods can be used besides the counter method, such as counting the number of threshold exceedances within a timer window, but these do not depart from the essential concept of this invention.

[0048] In one example, after determining that the common-mode inductor to be detected has a risk of failure, the method further includes: Obtain the identification information of the common-mode inductor to be detected; Fault information is generated and output based on the identification information.

[0049] It is readily understood that the present invention further provides a fault response implementation method, namely, generating and outputting fault information in order to promptly notify users, maintenance personnel or upper-level monitoring systems, thereby achieving rapid fault location and handling.

[0050] Specifically, after determining that the common-mode inductor under test is at risk of failure, the system automatically generates a fault message. This fault message contains at least one key data field: the identifier of the common-mode inductor under test. The "identifier of the common-mode inductor under test" refers to the identification information that uniquely distinguishes different common-mode inductors in the inverter. For example, in an inverter containing a first common-mode inductor L1 and a second common-mode inductor L2, the identifier can be "L1" or "L2", or the corresponding number "1" or "2", or other agreed-upon encoding methods (such as "CM1" and "CM2"). For inverters containing three or more common-mode inductors, the identifiers can be set as "L1", "L2", "L3", etc. Through this identifier, the receiver can clearly identify which specific common-mode inductor has failed, without needing to check the entire inverter one by one.

[0051] The generation of fault information can be performed by the inverter's controller (such as a microcontroller or digital signal processor). After determining a failure, the controller assembles the fault information into a complete message according to a preset communication protocol and data format. In addition to the common-mode inductor identifier, this message can also include other auxiliary information as needed, such as the fault code (e.g., "ERR_CM_L1_FAIL"), the timestamp of the fault occurrence, the current switching status of each PV branch, and the detected abnormal current amplitude. This additional information is not strictly necessary, but it can provide more reference for subsequent fault analysis and maintenance.

[0052] After the fault information is generated, the system outputs it through the corresponding communication interface. Common output methods include, but are not limited to, the following: local display via the inverter's built-in display screen or indicator lights, such as displaying the text "L1 common mode inductor failure" on the screen, or indicating the fault type through flashing codes of different colored indicator lights; uploading the fault information to a local monitoring terminal or home energy management system via a wired communication interface (such as RS485, CAN bus, Ethernet); and sending the fault information to a cloud server or the user's mobile application via a wireless communication module (such as Wi-Fi, 4G, Bluetooth, Zigbee). Those skilled in the art can choose the appropriate output method according to the specific hardware configuration of the inverter and the application scenario, and this invention does not limit this.

[0053] It is worth noting that the fault information includes the identifier of the common-mode inductor to be tested, a feature with significant technical advantages. In traditional inverter fault handling, when abnormal leakage current or common-mode related faults occur, only vague information such as "excessive leakage current" or "abnormal insulation impedance" is typically displayed. Maintenance personnel cannot determine which specific common-mode inductor or PV branch is faulty, often requiring multiple on-site inspections to pinpoint the fault source, consuming considerable time and manpower. This invention, by outputting fault information containing the specific common-mode inductor identifier, can accurately inform maintenance personnel whether L1 or L2 has failed (or a more specific common-mode inductor), thereby significantly shortening fault location time, achieving "one-time on-site, precise repair," and significantly reducing after-sales maintenance costs. Furthermore, for systems with remote monitoring capabilities, this fault information can be pushed to the maintenance platform in real time, supporting remote diagnosis and early warning, further enhancing the system's intelligence and maintainability.

[0054] In practical implementation, fault information output can be combined with the system's protection strategy. For example, while generating and outputting fault information, the system can execute a shutdown protection action and store the fault information in a local log for later retrieval. After the output is completed, the system can remain in the fault state until a manual reset command is received or the fault is automatically resolved. Those skilled in the art can design the system behavior after a fault according to actual needs, as long as it does not depart from the essential concept of this invention.

[0055] In one example, after determining that the common-mode inductor to be detected has a risk of failure, the method further includes: Control the shutdown of the energy storage inverter or limit its power output.

[0056] It's easy to understand that common-mode inductor failure is a critical component malfunction within the inverter. Once the common-mode inductor experiences core saturation, partial short circuits in the windings, or insulation degradation, its ability to suppress common-mode interference current will significantly decrease, leading to an abnormally large increase in leakage current from the PV side to ground. If the leakage current continues to exceed the limit, it may not only trigger the inverter's own leakage current protection, causing frequent error reports and shutdowns, affecting normal power generation, but more seriously, it may cause the equipment casing to become electrified, posing a risk of electric shock to installation and maintenance personnel, and even causing an electrical fire. Therefore, it is crucial to take timely protective actions after detecting common-mode inductor failure.

[0057] In this example, "controlling the shutdown of the energy storage inverter" refers to issuing a command through the controller to stop the inverter from power conversion. Specific implementation methods may include: disconnecting the grid-connection relay between the inverter and the grid, thus disconnecting the inverter from the grid; simultaneously disconnecting the electronic switch at the PV side input, cutting off the input to the photovoltaic modules; and controlling all power switching transistors (such as IGBTs or MOSFETs) inside the inverter to turn off, stopping energy conversion. After shutdown, the inverter enters a safe fault state and ceases power generation or energy storage operations until the fault is cleared and manually reset. This complete shutdown protection method is suitable for situations where the common-mode inductor failure is severe, leakage current is large, or the system cannot continue to operate safely.

[0058] In this example, "limiting power output" refers to reducing the inverter's output power to a safe level without a complete shutdown. Specific implementation methods include actively reducing the inverter's transmission power by lowering the inverter's switching frequency, limiting the output current command, or reducing the MPPT's tracking voltage. Since the cross-branch crosstalk current generated by common-mode inductor failure is typically positively correlated with the inverter's operating power—the higher the power, the larger the abnormal current—limiting power output can effectively reduce the amplitude of the abnormal current, bringing it back within a safe range, thereby avoiding triggering leakage current protection or eliminating safety hazards. This method is suitable for situations where the common-mode inductor is in the early stages of failure and the abnormal current is not yet severe. It can maintain a certain power generation capacity of the inverter while ensuring safety, reducing power generation losses caused by a complete shutdown.

[0059] It should be noted that the choice between shutting down or limiting power output can be tiered based on the severity of the failure. For example, when the detected abnormal current amplitude exceeds a first threshold (but is less than a second threshold), the system can prioritize limiting power output; when the abnormal current amplitude exceeds a second threshold (a higher threshold), the system will shut down completely. This invention does not limit the specific tiering strategy; those skilled in the art can configure it reasonably according to actual safety requirements and product design.

[0060] This example demonstrates how proactively implementing shutdown or power limiting protection upon detecting common-mode inductor failure effectively avoids safety risks such as electrical fires, equipment damage, and electric shocks caused by excessive leakage current due to common-mode inductor failure, significantly improving the inherent safety level of the energy storage inverter. Simultaneously, the power limiting output strategy provides a compromise solution for minor faults, balancing safety and power generation benefits, and avoiding power generation losses caused by direct shutdown due to minor faults.

[0061] In the second embodiment, the preset threshold is greater than the amplitude of the induced noise current when the branch is disconnected under normal operating conditions, and less than the amplitude of the normal power generation current.

[0062] It's important to clarify that, firstly, the so-called "induced noise current when the branch is disconnected under normal operating conditions" refers to a weak current naturally present in the disconnected branch due to factors such as electromagnetic coupling, spatial electromagnetic interference, and the charging and discharging of the Y capacitor, under the conditions that the inverter is operating normally, all common-mode inductors are in a healthy state, and the PV branch corresponding to the non-detection common-mode inductor is electronically switched off. The amplitude of this induced noise current is typically very small, generally in the sub-milliampere to milliampere range. For example, in a typical three-phase energy storage inverter, the induced noise current when the branch is disconnected under normal operating conditions is usually less than 1 milliampere. The preset threshold must be greater than the amplitude of this induced noise current; otherwise, normal noise fluctuations will be misinterpreted as abnormal currents, leading to frequent false alarms. In other words, the threshold needs to be higher than the noise floor to ensure that the detection system remains stable when there is no fault and does not trigger false failure detections.

[0063] Secondly, the preset threshold must be lower than the amplitude of the normal power generation current. The "normal power generation current" refers to the normal power current delivered by the photovoltaic modules to the inverter when the PV branch is in operation. The amplitude of this current depends on the irradiance and module capacity, and is typically in the ampere range (e.g., 5 amperes to 20 amperes). The preset threshold is much lower than the normal power generation current because this invention detects the abnormal coupling current in the branch, not the normal power generation current in the operating branch. The abnormal current in the branch is caused by cross-branch crosstalk current due to common-mode inductor failure. Although its amplitude is significantly higher than induced noise, it is still much lower than the normal power generation current (e.g., between 5 mA and 30 mA). Therefore, as long as the threshold is set within this range, the abnormal current can be effectively distinguished from the normal power generation current, while avoiding confusion with the large current in the operating branch.

[0064] Based on the above two conditions, the preset threshold is limited to a specific range: greater than the upper limit of the induced noise current and less than the lower limit of the normal power generation current. In practical engineering applications, this threshold can be calibrated according to the circuit parameters and electromagnetic compatibility characteristics of the specific product. As a preferred example, the threshold can be set between 3 mA and 30 mA. For example, when the induced noise current is approximately 0.5 mA, the threshold can be set to 3 mA; when the induced noise current is slightly higher (e.g., 2 mA), the threshold can be increased accordingly to 5 mA or 10 mA. Regardless of the specific value, as long as the functional requirement of "greater than noise and less than normal power generation current" is met, it falls within the protection scope of this invention.

[0065] Those skilled in the art should understand that the selection of the threshold needs to strike a balance between sensitivity and interference immunity. A threshold that is too low may lead to sensitivity to noise and an increased false alarm rate; a threshold that is too high may miss weak abnormal currents caused by early minor failures. By setting the threshold above the induced noise and below the normal power generation current, and combining it with the aforementioned delayed confirmation mechanism (e.g., determining the threshold only after N consecutive exceedances), it is possible to effectively suppress false alarms while ensuring high detection sensitivity, thereby achieving optimal detection performance.

[0066] The present invention also proposes a storage medium storing a PV common-mode inductor failure detection program for an energy storage inverter, wherein the PV common-mode inductor failure detection program for an energy storage inverter implements the steps of the PV common-mode inductor failure detection method for an energy storage inverter when executed by a processor.

[0067] The storage medium refers to any physical carrier capable of storing program code, including but not limited to: read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), solid-state drive (SSD), optical disc (CD-ROM, DVD), USB flash drive, magnetic tape, etc. This medium can be volatile or non-volatile, rewritable or read-only; this invention does not limit its scope. Any medium capable of persistently storing program instructions in binary or other encoded form and being read and executed by the processor when needed falls within the protection scope of this invention.

[0068] The program stored on this medium, namely the PV common-mode inductor failure detection program for the energy storage inverter, is a set of computer-readable instructions. When this program is loaded and executed by the controller inside the inverter (such as a microcontroller (MCU), digital signal processor (DSP), ARM processor, or other embedded processor), the processor will perform the following operations in the logical order set by the program: obtain the on / off status of the electronic switches of each PV input branch; determine whether the preset trigger condition is met, that is, only one PV branch in the group corresponding to the common-mode inductor to be detected is engaged and every PV branch corresponding to all non-detected common-mode inductors is disconnected; when the trigger condition is met, collect the current of a disconnected branch corresponding to any non-detected common-mode inductor and calculate the amplitude; compare the amplitude with a preset threshold, and if it is greater than the threshold, determine that the common-mode inductor to be detected has failed. The program can also further implement any additional functions in the aforementioned embodiments, such as a delayed confirmation mechanism (e.g., determining failure only after N consecutive exceedances of the threshold), incrementing and resetting the fault counter, generating and outputting fault information containing the common-mode inductor identifier, and performing shutdown or power limiting protection actions.

[0069] The present invention also proposes an energy storage inverter, the energy storage inverter comprising: Multiple common-mode inductors; Multiple PV input branches, each of the aforementioned common-mode inductors corresponds to at least one PV input branch; An electronic switch is installed in each PV input branch; A current detection sensor is installed in each PV input branch; The controller is connected to the electronic switches and current detection sensors in each PV input branch; The controller is configured to perform the steps of the energy storage inverter PV common mode inductor failure detection method.

[0070] It should be explained that multiple common-mode inductors are located on the PV side of the energy storage inverter. Each common-mode inductor corresponds to at least one PV input branch and is used to suppress common-mode interference current in the corresponding branch. A "common-mode inductor" is a magnetic core device with two or more windings that presents low impedance to differential-mode current and high impedance to common-mode current during normal operation. In this invention, the multiple common-mode inductors are independent of each other and serve different PV branch groups. For example, in a typical configuration, the energy storage inverter includes a first common-mode inductor and a second common-mode inductor. The first common-mode inductor corresponds to PV1 and PV2 branches, and the second common-mode inductor corresponds to PV3 and PV4 branches. It should be noted that the number of common-mode inductors is not limited to two; it can be three, four, or more. The number of PV branches corresponding to each common-mode inductor is also not limited to two; it can be one or more. This invention does not impose any limitations on this.

[0071] Multiple PV input branches are used to connect to external photovoltaic (PV) modules, introducing the DC power generated by the PV modules into the energy storage inverter. Each PV input branch typically includes a positive bus and a negative bus, which are connected to the positive and negative output terminals of the PV modules, respectively. Each PV input branch is electrically independent, and its current loop is coupled only within the inverter through bus capacitors or common-mode paths.

[0072] An electronic switch is installed in each PV input branch. Specifically, an electronic switch is connected in series on the positive bus of each PV input branch to independently control the connection or disconnection of that branch. This electronic switch can be a mechanical switch such as a relay or contactor, or a semiconductor switch such as a MOSFET or IGBT, and its control terminal is connected to the corresponding output port of the controller. When the controller issues a closing command, the electronic switch is turned on, and that PV input is connected to the inverter's main circuit; when the controller issues a disconnect command, the electronic switch is turned off, isolating that PV input from the main circuit.

[0073] A current sensing sensor is also installed in each PV input branch. This sensor is used to detect the current value of its branch in real time and convert the detected current signal into an electrical signal (such as a voltage signal or a digital signal) that the controller can recognize. The current sensing sensor can be implemented in various ways, such as a Hall current sensor, a shunt resistor with a differential amplifier, or a current transformer. The sensor's output is connected to the controller's analog or digital input port, allowing the controller to read the instantaneous current value of each PV input branch. It is worth noting that when detecting abnormal current in a branch, the current sensing sensor is used to obtain the current signal. Even if the electronic switch of that branch is open, the sensor can still detect the weak current flowing through that branch (including induced noise current and abnormal coupling current caused by common-mode inductor failure).

[0074] The controller is the core control unit of the energy storage inverter, connected to the electronic switches and current sensors in each PV input branch. Specifically, the controller's control output port is connected to the control terminals of each electronic switch to control the on / off state of each PV branch; the controller's signal input port is connected to the output terminals of each current sensor to read the real-time current value of each PV branch. The controller is typically composed of a microcontroller (MCU), digital signal processor (DSP), ARM processor, or other integrated circuits with computing and processing capabilities, and internally integrates peripheral modules such as analog-to-digital converters (ADCs), general-purpose input / output interfaces (GPIO), and communication interfaces. The controller also stores a computer-executable program (e.g., stored in internal flash memory or external storage media), which, when executed, causes the controller to perform the steps of the PV common-mode inductor failure detection method described in any of the aforementioned embodiments of the energy storage inverter.

[0075] The operation of this energy storage inverter is as follows: During operation, the controller reads the status of each electronic switch in real time to determine whether each PV input branch is connected or disconnected. Simultaneously, the controller continuously monitors the current value of each PV input branch (via current sensing sensors). The controller determines whether the triggering conditions are met using the aforementioned method (i.e., only one PV branch in the group corresponding to the common-mode inductor under test is connected, and all PV branches corresponding to non-detected common-mode inductors are disconnected). If the triggering conditions are met, the controller collects the current of a disconnected branch corresponding to any non-detected common-mode inductor through the current sensing sensors, calculates the amplitude, and compares it with a preset threshold. Based on the comparison result, it determines whether the common-mode inductor under test is at risk of failure. After determining failure, the controller can further generate fault information and output it through the communication interface, or execute protective actions such as shutdown or power limiting.

[0076] With the above-described structure, this energy storage inverter can achieve online detection of common-mode inductor failure without adding any extra hardware, utilizing existing electronic switches, current sensors, and controllers. This fully demonstrates the high compatibility of this invention with existing inverter hardware, facilitating functional enhancements through software upgrades on existing products.

[0077] The specific steps of the PV common-mode inductor failure detection method for the energy storage inverter are as described in the above embodiments. Since this energy storage inverter adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0078] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for detecting failure of a PV common-mode inductance of an energy storage inverter, characterized in that, The PV side of the energy storage inverter includes multiple common-mode inductors, and each common-mode inductor corresponds to at least one PV input branch. The method for detecting the failure of the PV common-mode inductor in the energy storage inverter includes: Obtain the on / off status of the electronic switches in each PV input branch; Determine whether the on / off state of the electronic switches of each PV input branch meets the preset triggering conditions. The triggering conditions are: only one PV branch in the PV branch group corresponding to the common-mode inductor to be detected is in the on state, and each PV branch corresponding to each non-detected common-mode inductor is in the off state; wherein, the common-mode inductor includes: the common-mode inductor to be detected and the non-detected common-mode inductor. When the triggering condition is met, detect the current of any PV branch that is in an open state corresponding to any non-detected common-mode inductor, and calculate the current amplitude. If the current amplitude is greater than a preset threshold, it is determined that the common-mode inductor to be tested is at risk of failure.

2. The energy storage inverter PV common mode inductance failure detection method of claim 1, wherein, When the triggering condition is met, the current of any PV branch that is in an open state corresponding to any non-detected common-mode inductor is detected, and the current amplitude is calculated, including: When the triggering condition is met, the current of any PV branch that is in the open state corresponding to any non-detected common mode inductor is detected N times, and the current amplitude of each detection is calculated. Accordingly, if the current amplitude is greater than a preset threshold, it is determined that the common-mode inductor under test has a risk of failure, including: When the current amplitude obtained from N consecutive samplings is greater than the preset threshold, it is determined that the common-mode inductor to be detected has a risk of failure, where N is an integer greater than or equal to 2.

3. The energy storage inverter PV common mode inductance failure detection method of claim 2, wherein, When the triggering condition is met, the current of any PV branch that is in an open state corresponding to any non-detected common-mode inductor is detected N times, and the current amplitude of each detection is calculated. The process also includes: Iterate through the fault count values ​​where the current amplitude is greater than the preset threshold; If the fault count value is equal to N, it is determined that the common mode inductor to be tested is at risk of failure. If the current amplitude is less than the preset threshold, the fault count value is reset to zero.

4. The energy storage inverter PV common mode inductance failure detection method of claim 1, wherein, After determining that the common-mode inductor under test has a risk of failure, the method further includes: Obtain the identification information of the common-mode inductor to be detected; Fault information is generated and output based on the identification information.

5. The energy storage inverter PV common-mode inductance failure detection method of claim 1, wherein, After determining that the common-mode inductor under test has a risk of failure, the method further includes: Control the shutdown of the energy storage inverter or limit its power output.

6. The energy storage inverter PV common mode inductance failure detection method of any one of claims 1 to 5, wherein, The preset threshold is greater than the amplitude of the induced noise current when the branch is disconnected under normal operating conditions, but less than the amplitude of the normal power generation current.

7. A storage medium, characterized by The storage medium stores a PV common-mode inductor failure detection program for an energy storage inverter. When the PV common-mode inductor failure detection program is executed by the processor, it implements the steps of the PV common-mode inductor failure detection method for an energy storage inverter as described in any one of claims 1 to 6.

8. An energy storage inverter, characterized by, The energy storage inverter includes: Multiple common-mode inductors; Multiple PV input branches, each of the aforementioned common-mode inductors corresponds to at least one PV input branch; An electronic switch is installed in each PV input branch; A current detection sensor is installed in each PV input branch; The controller is connected to the electronic switches and current detection sensors in each PV input branch; The controller is configured to perform the steps of the energy storage inverter PV common mode inductor failure detection method as described in any one of claims 1 to 6.

9. The energy storage inverter of claim 8, wherein, The electronic switch is a relay or a semiconductor switch.

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