Contact failure diagnosis method, device and energy storage system

Abstract

This application provides a fault diagnosis method, apparatus, and energy storage system for contactors, relating to the field of energy storage technology. The method includes: acquiring the current operating state of the energy storage system, which may be a static state or a charging / discharging state; acquiring the status signal of the contactor's auxiliary contacts, the internal total voltage on the contactor's battery side, and the external total voltage on the contactor's load side; calculating the voltage difference between the internal and external total voltages based on the internal and external total voltages; when the operating state is static, determining whether the contactor's state is abnormal based on the status signal of the contactor's auxiliary contacts and the voltage difference between the internal and external total voltages; when the operating state is charging / discharging, acquiring the branch current of the contactor's main contacts; and determining whether the contactor's state is abnormal based on the status signal of the contactor's auxiliary contacts, the voltage difference between the internal and external total voltages, and the branch current of the contactor's main contacts. The method provided in this application helps reduce false alarms and missed alarms for contactor status faults, improving the accuracy and reliability of contactor fault detection.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a fault diagnosis method, device and energy storage system for a contactor. Background Technology

[0002] With the rapid development of the new energy industry, energy storage systems are widely used in grid peak shaving, renewable energy consumption, and industrial and commercial electricity management. Among these applications, the high-voltage DC contactor, as the core control component of the high-voltage box in an energy storage system, plays a crucial role in connecting or disconnecting the high-voltage DC circuit between the energy storage battery and the external circuit, directly affecting the system's safety and reliability. During charging and discharging, the contactor responds to commands from the Battery Management System (BMS) or control system to control the energy transmission of the energy storage system, ensuring a stable and on-demand power delivery.

[0003] Currently, fault diagnosis of contactor status mainly relies on detecting the contactor's engaged or disengaged state through auxiliary contacts. This method suffers from limitations such as simplistic detection, susceptibility to interference, and inability to provide comprehensive diagnosis. This can lead to false alarms and missed alarms, affecting the reliability and safety of energy storage systems. Summary of the Invention

[0004] This application provides a fault diagnosis method, device, and energy storage system for contactors, which helps to reduce false alarms and missed alarms of contactor status faults, improve the accuracy and reliability of contactor fault detection, reduce the failure rate of energy storage systems, and ensure the safe operation of energy storage systems.

[0005] Firstly, this application provides a fault diagnosis method for a contactor, including: Obtain the current operating status of the energy storage system, which may be either in a static state or a charging / discharging state. Acquire the status signals of the contactor auxiliary contacts, the internal total voltage on the contactor battery side, and the external total voltage on the contactor load side; Calculate the pressure difference between the internal and external total pressures based on the internal and external total pressures; When the operating state is stationary, the status of the contactor is determined based on the status signal of the contactor auxiliary contacts and the pressure difference between the internal and external total pressure. When the operating state is charging and discharging, the branch current of the contactor's main contacts is obtained; based on the status signal of the contactor's auxiliary contacts, the voltage difference between the internal and external total voltages, and the branch current of the contactor's main contacts, it is determined whether the contactor's state is abnormal.

[0006] In one possible implementation, the contactor state includes the contactor body state and the contactor connection state; determining whether the contactor state is abnormal based on the status signal of the contactor auxiliary contacts and the total internal and external voltage difference includes: If the status signal of the contactor's auxiliary contact is low and the total internal and external voltage difference is greater than the first preset threshold, then the contactor body is determined to be in an abnormal state, and the contactor connection is abnormal; or If the status signal of the auxiliary contact of the contactor is low and the total internal and external voltage difference is less than or equal to the first preset threshold, then the contactor body is determined to be in an abnormal state and the contactor connection is normal.

[0007] In one possible implementation, the contactor state includes the contactor body state and the contactor connection state; the abnormality of the contactor state is determined based on the status signal of the contactor auxiliary contacts, the internal and external total voltage difference, and the branch current of the contactor main contacts, including: If the status signal of the contactor's auxiliary contact is low, and the total voltage difference between the internal and external contacts is less than or equal to the first preset threshold, and the branch current of the contactor's main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor's auxiliary contact is low, and the total voltage difference between the internal and external contacts is less than or equal to the first preset threshold, and the branch current of the contactor's main contact is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor's auxiliary contact is low, the total voltage difference between the inside and outside is greater than the first preset threshold, and the branch current of the contactor's main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, but the contactor connection is abnormal; or If the status signal of the contactor's auxiliary contact is low, and the total internal and external voltage difference is greater than the first preset threshold, and the branch current of the contactor's main contact is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, but the contactor connection is abnormal; or If the status signal of the contactor's auxiliary contact is high, and the total voltage difference between the internal and external contacts is less than or equal to the first preset threshold, and the branch current of the contactor's main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor's auxiliary contact is high, and the total voltage difference between the internal and external contacts is less than or equal to the first preset threshold, and the branch current of the contactor's main contact is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor's auxiliary contact is high, and the total voltage difference between the internal and external contacts is greater than the first preset threshold, and the branch current of the contactor's main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, but the contactor connection is abnormal; or If the status signal of the auxiliary contact of the contactor is high, the voltage difference between the internal and external total voltages is greater than the first preset threshold, and the branch current of the main contact of the contactor is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is abnormal.

[0008] One possible implementation of the method also includes: When both the contactor body status and the contactor connection status are normal, the control energy storage system will perform normal charging and discharging. When at least one of the contactor body state and contactor connection state is abnormal, the energy storage system is prohibited from charging and discharging.

[0009] One possible implementation of the method also includes: Obtain the temperature at the contactor connection point; Check if the temperature at the contactor connection is normal; If the temperature at the contactor connection is normal, the energy storage system will continue normal charging and discharging; or If the temperature at the contactor connection is abnormal, the energy storage system is prohibited from charging and discharging.

[0010] One possible implementation involves determining whether the temperature at the contactor connection is normal, including: If the temperature at the contactor connection exceeds the temperature threshold, the temperature at the contactor connection is determined to be abnormal; or If the temperature at the contactor connection is less than or equal to the temperature threshold, the temperature at the contactor connection is considered normal.

[0011] In one possible implementation, when a first contactor is connected in parallel with another contactor, determining whether the temperature at the contactor connection point is normal includes: Obtain the temperature at the connection point of the first contactor; Calculate the temperature difference between the contactor connection and the first contactor connection; If the difference is within the preset range, the temperature at the contactor connection is determined to be normal; or If the difference is not within the preset range, the temperature at the contactor connection is determined to be abnormal.

[0012] One possible implementation of the method also includes: The status signal of the contactor auxiliary contact is acquired continuously for a preset number of times. When the status signals of the contactor auxiliary contact are all at the same level, the status signal of the contactor auxiliary contact is determined to be a valid signal.

[0013] In one possible implementation, before calculating the pressure difference between the internal and external total pressures based on the internal and external total pressures, the method further includes: The internal and external total pressures are filtered to remove abnormal offset values.

[0014] Secondly, this application provides a fault diagnosis device for a contactor, comprising: The first acquisition module is used to acquire the current operating status of the energy storage system, which is either a static state or a charging / discharging state. The second acquisition module is used to acquire the status signal of the contactor auxiliary contact, the internal total voltage on the contactor battery side, and the external total voltage on the contactor load side. The calculation module is used to calculate the pressure difference between the internal and external total pressures based on the internal and external total pressures. The fault diagnosis module is used to determine whether the contactor is in an abnormal state based on the status signal of the contactor auxiliary contacts and the pressure difference between the internal and external total pressure when the operating state is stationary. When the operating state is charging and discharging, the branch current of the contactor's main contacts is obtained; based on the status signal of the contactor's auxiliary contacts, the voltage difference between the internal and external total voltages, and the branch current of the contactor's main contacts, it is determined whether the contactor's state is abnormal.

[0015] Thirdly, this application provides an energy storage system, including: a battery management system, the battery management system including a battery control unit, the battery control unit being used to collect the status signal of the contactor auxiliary contact, the internal total voltage on the contactor battery side, the external total voltage on the contactor load side, the branch current of the contactor main contact and the temperature at the contactor connection, the battery management system being used to acquire the signals collected by the battery control unit and execute the contactor fault diagnosis method as described in the first aspect.

[0016] The beneficial effects of this application are as follows: This application provides a contactor fault diagnosis method, device, and energy storage system. By acquiring the current operating status of the energy storage system, when the system is in a static state, the method determines whether the contactor is abnormal based on the status signal of the contactor's auxiliary contacts and the internal and external total voltage difference. When the system is in a charging / discharging state, the method determines whether the contactor is abnormal based on the status signal of the contactor's auxiliary contacts, the internal and external total voltage difference, and the branch current of the contactor's main contacts. This application differentiates fault detection by distinguishing the operating states of the energy storage system. In the static state, auxiliary contact and voltage difference detection are performed; in the charging / discharging state, auxiliary contact, voltage difference, and current detection are performed. This achieves multi-parameter fusion diagnosis, which helps to accurately match operating conditions, reduce false alarms and missed alarms for contactor status faults, improve the accuracy and reliability of contactor fault detection, reduce the failure rate of the energy storage system, and ensure the operational safety of the energy storage system. Attached Figure Description

[0017] Figure 1 A schematic diagram of the primary circuit of the high-voltage box provided in an embodiment of this application; Figure 2 A flowchart illustrating the fault diagnosis method for a contactor provided in an embodiment of this application; Figure 3 This is a schematic diagram of the fault diagnosis device for a contactor provided in an embodiment of this application. Detailed Implementation

[0018] In this embodiment of the application, unless otherwise stated, the character " / " indicates that the preceding and following objects are in an OR relationship. For example, A / B can represent A or B. "AND / OR" describes the relationship between the associated objects, indicating that three relationships can exist. For example, A AND / OR B can represent: A existing alone, A and B existing simultaneously, and B existing alone.

[0019] It should be noted that the terms "first" and "second" used in the embodiments of this application are used only for distinguishing descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated, nor should they be construed as indicating or implying order.

[0020] In the embodiments of this application, "at least one" means one or more, and "more than one" means two or more. Furthermore, "at least one of the following" or similar expressions refer to any combination of these items, which may include any combination of a single item or a plurality of items. For example, at least one of A, B, or C can represent: A, B, C, A and B, A and C, B and C, or A, B, and C. Each of A, B, and C can be an element itself or a set containing one or more elements.

[0021] In this application, terms such as "exemplary," "in some embodiments," and "in another embodiment" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the term "exemplary" is intended to present the concept in a concrete manner.

[0022] In the embodiments of this application, the terms "of," "corresponding (relevant)," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction, their meanings are consistent. Similarly, in the embodiments of this application, "communication" and "transmission" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction, their meanings are consistent. For example, transmission can include sending and / or receiving, and can be a noun or a verb.

[0023] In the embodiments of this application, the term "equal to" can be used in conjunction with "greater than" to apply to technical solutions employing the condition of "greater than", and can also be used in conjunction with "less than" to apply to technical solutions employing the condition of "less than". It should be noted that when "equal to" is used with "greater than", it cannot be used with "less than"; and when "equal to" is used with "less than", it cannot be used with "greater than".

[0024] The following explains some of the terms used in this application.

[0025] 1. Contactor: In the high-voltage box of the battery pack, the contactor is an integrated device that includes main contacts and auxiliary contacts. The main contacts are connected in series with the high-voltage DC bus and are responsible for switching the contactor on and off, while the auxiliary contacts are responsible for providing feedback on the actual state of the contactor (such as closed or open).

[0026] Auxiliary contacts include normally open (NOT) and normally closed (NC) contacts. If it is a NOT contact, the auxiliary contact provides a high-level response when the contactor is open and a low-level response when the contactor is closed. If it is a NOT contact, the auxiliary contact provides a low-level response when the contactor is open and a high-level response when the contactor is closed.

[0027] In the following embodiments of this application, the auxiliary contact uses a "normally open" contact, that is, it adopts the logic of "closed = low level, open = high level", mainly to prevent safety accidents caused by wire breakage or poor contact. If the cable connecting the auxiliary contact is broken or the plug is loose, the feedback of the auxiliary contact will always be high level. Since the logic corresponding to high level is "open", the system will mistakenly think that the contactor is not closed, thereby prohibiting charging and discharging or reporting a fault.

[0028] 2. Static state and charging / discharging state: The static state refers to the energy storage system being in a non-working state (or "standby" state) with the contactor in the open state; the charging / discharging state refers to the energy storage system being charging or discharging with the contactor in the closed state.

[0029] 3. Internal Total Voltage and External Total Voltage: Internal total voltage is the cumulative total voltage of all cells in the battery cluster. It refers to the voltage between the positive and negative terminals of the contactor near the battery cluster inside the high-voltage box. Its value is equal to the cumulative total voltage obtained by adding up the individual cell voltages of all cells in the battery cluster. It is used to characterize the voltage state of the battery cluster itself. External total voltage is the external DC bus voltage. It refers to the voltage between the positive and negative terminals of the contactor near the external load or PCS inside the high-voltage box. It is used to characterize the voltage state of the external DC bus.

[0030] When the contactor is in the open state, the internal total voltage remains the cumulative total voltage of the battery cluster, while the external total voltage is close to zero. When the contactor is in the closed state, the internal and external total voltages tend to be the same. The BMS realizes contactor fault detection and high-voltage circuit status monitoring by comparing the difference between the internal and external total voltages in real time.

[0031] 4. Branch current of the contactor main contacts: refers to the current flowing through the contactor main contacts.

[0032] 5. Temperature at the contactor connection: This refers to the temperature at the connection point between the contactor and external conductive components (such as copper busbars and connecting terminals) inside the high-voltage box. For example, the temperature at the connection point between the contactor terminals and the bolted copper busbar.

[0033] 6. Contactor Body Status: This is used to characterize the mechanical reliability and electrical conductivity of the contactor's internal electromagnetic drive mechanism and main contact assembly. Specifically, it reflects whether the contactor can strictly follow the control command to perform the engagement or disengagement operation. A normal contactor body status means that the contactor engages or disengages normally. An abnormal contactor body status includes internal fault characteristics such as contact sticking, inability to engage, and coil open circuit.

[0034] 7. Contactor connection status: This is used to characterize the reliability of the physical connection between the main contacts of the contactor and external conductive components (such as copper busbars and connecting terminals). Abnormal contactor connection status is specifically manifested in abnormal phenomena such as contact surface tightness, oxidation and corrosion degree, and contact resistance, including external connection defects such as loose bolts, terminal burning, and copper busbar oxidation.

[0035] The following section describes the problems existing in the relevant technologies.

[0036] Traditional contactor status detection methods primarily rely on single signal detection from the contactor's auxiliary contacts. For example, when the BMS sends a closing command, the system determines whether the contactor has properly engaged by detecting whether the auxiliary contacts output a low-level signal; conversely, when a closing command is sent, it determines whether the contactor has successfully closed by detecting whether the auxiliary contacts output a high-level signal. This detection method has significant technical drawbacks: (1) Limited detection dimensions, unable to provide a comprehensive diagnosis. Current detection technologies only focus on the mechanical operating state of the contactor body, ignoring the physical connection quality between the contactor and the external circuit connection point. In practical applications, problems such as improper installation processes, bolt loosening due to long-term vibration, and copper busbar oxidation caused by environmental corrosion often lead to abnormally increased contact resistance at the contactor connection point, which may cause local overheating or even fire risks. Because traditional detection methods lack means to monitor the connection status, such faults often cannot be detected in a timely manner.

[0037] (2) Poor anti-interference capability. The single auxiliary contact detection is easily affected by external electromagnetic interference, signal cable aging or BMS sampling error, resulting in a high false alarm rate. In actual operation, there are often situations where the auxiliary contact signal is abnormal but the contactor is actually working normally. The system misjudges it as a contactor failure and stops operating, affecting the normal operation of the energy storage system and causing a lot of unnecessary maintenance and downtime losses.

[0038] (3) Inaccurate fault location. Current technology cannot distinguish between contactor body state faults and connection state faults. When an anomaly is detected, maintenance personnel have difficulty quickly locating the root cause of the problem—whether it is a body state fault such as contactor internal contact sticking or coil damage, or an external connection problem such as loose copper busbar connection or terminal oxidation, which leads to difficult maintenance decisions and increases fault repair time and system downtime costs.

[0039] Based on the above problems, this application proposes a fault diagnosis method, device, and energy storage system for contactors, which helps to reduce false alarms and missed alarms of contactor status faults, improve the accuracy and reliability of contactor fault detection, reduce the failure rate of energy storage systems, and ensure the safe operation of energy storage systems.

[0040] Now combined Figure 1 and Figure 2 The fault diagnosis method for contactors provided in the embodiments of this application will be described.

[0041] Figure 1 This is a schematic diagram of the primary circuit of the high-voltage box provided in an embodiment of this application. Figure 1 As shown, the primary circuit of the high-voltage box (also called the main circuit or power circuit) refers to the electrical circuit that carries the main power current, used to represent the path of electrical energy flowing from the battery pack to external devices (or reverse charging). The primary circuit of the high-voltage box typically includes the following core components and their connections: (1) DC input or output terminals: Interfaces for connecting the positive and negative terminals of the battery pack, such as... Figure 1 The interfaces corresponding to "B+" and "B-" shown in the diagram.

[0042] (2) Fuse: Overcurrent and short-circuit protection device, usually located at the positive input terminal, as the last physical protection.

[0043] (3) Main positive contactor KM1: a key device for controlling the opening and closing of the positive main circuit, including main contacts, auxiliary contacts and coil.

[0044] (4) Main negative contactor KM2: a key device for controlling the opening and closing of the negative main circuit, including main contacts, auxiliary contacts and coil.

[0045] (5) Pre-charge circuit: It consists of a pre-charge contactor KM3 and a pre-charge resistor R connected in series and in parallel across the main positive contactor KM1. Through the pre-charge contactor KM3 and the pre-charge resistor R, it prevents the large current surge at the moment the main circuit is turned on from damaging downstream equipment (such as the capacitor of the power conversion system, PCS).

[0046] (6) Hall current sensor: can be installed on the positive or negative bus to monitor the magnitude of charging and discharging current in real time.

[0047] (7) Circuit breaker QF: When an overload or short circuit occurs on the line, the circuit breaker can automatically trip to cut off the fault current and prevent the accident from escalating. After the fault is cleared, normal power supply can be restored simply by manual or automatic reset.

[0048] In an energy storage system, several individual battery cells (or battery modules) are combined in series, parallel, or series-parallel configurations to form a battery cluster. Multiple battery modules are connected in series to form a battery cluster. Each battery cluster is typically equipped with a high-voltage box (containing contactors, fuses, etc.). When a battery cluster malfunctions (such as overheating or insulation abnormalities), the BMS can control the high-voltage box contactor of that cluster to disconnect, isolating the battery cluster, while other normal battery clusters can continue to operate without affecting the operation of the entire system.

[0049] The high-voltage box of the battery cluster houses the Battery Control Unit (BCU), which is responsible for managing the voltage and current of the entire battery cluster, controlling the on / off state of the main positive or negative contactor, performing cluster-level protection (such as overcurrent, overvoltage, and insulation detection), and also collecting status signals of the contactor auxiliary contacts, the internal total voltage on the contactor battery side, the external total voltage on the contactor load side, the branch current of the contactor main contacts, and the temperature at the contactor connection. It communicates with the BMS and uploads the collected signals to the BMS for contactor fault detection.

[0050] like Figure 1 As shown, the BCU typically controls the contactor coil via Digital Output (DO) and monitors the status of its auxiliary contacts via Digital Input (DI). Specifically, pins "DO1H" and "DO2H" are connected to the coils of the two contactors respectively, and the BCU outputs a control signal through the DO pin to drive the contactor coil. Pins "V1+" and "V1-" are used to output the detection voltage and are connected to the auxiliary contacts via wires. Pins "DI1L" and "DI2H" are used to read the status of the contactor's auxiliary contacts to confirm whether the control command output by the DO pin has been executed correctly. Therefore, the status signal of the auxiliary contact of the main positive contactor can be acquired through pin "DI1L", and the status signal of the auxiliary contact of the main negative contactor can be acquired through pin "DI2L".

[0051] The total internal pressure on the contactor battery side collected by the BCU is as follows: Figure 1 The voltages corresponding to "B+" and "B-" shown are the total external voltages on the load side of the contactor, as shown below. Figure 1 The voltages corresponding to “Vp+” and “Vp-” shown are obtained by detecting the branch current of the main contact of the contactor through a Hall current sensor, and the temperature at the contactor connection is obtained by detecting temperature measuring point 1 and temperature measuring point 2.

[0052] Figure 2 A flowchart illustrating the contactor fault diagnosis method provided in this application embodiment is shown, specifically including the following steps: Step S21: Obtain the current operating status of the energy storage system.

[0053] Specifically, the operating status of the energy storage system is either a static state or a charging / discharging state. The operating status of the energy storage system can be determined by the operating status of the battery pack or by the operating power of the PCS.

[0054] Step S22: Obtain the status signal of the contactor auxiliary contact, the internal total voltage on the contactor battery side, and the external total voltage on the contactor load side.

[0055] Specifically, the BCU collects the status signals of the auxiliary contacts of the contactor, the internal total voltage on the battery side of the contactor, and the external total voltage on the load side of the contactor in the primary circuit of the high-voltage box.

[0056] In this step, to determine the fault status of the main positive contactor, the BCU can acquire the status signal of the auxiliary contacts of the main positive contactor through pin "DI1L"; to determine the fault status of the main negative contactor, the BCU can acquire the status signal of the auxiliary contacts of the main negative contactor through pin "DI2L". The total internal voltage on the battery side of the contactor acquired by the BCU is... Figure 1 The voltage difference between "B+" and "B-" shown is the total external voltage on the load side of the contactor. Figure 1 The voltage difference between “Vp+” and “Vp-” is shown in the diagram.

[0057] The auxiliary contacts of a contactor may experience brief jitter (from microseconds to milliseconds) during the instant of operation (closing or opening) due to mechanical bounce (e.g., multiple level transitions during a single closing process). Furthermore, the switching on and off of high-current circuits in energy storage systems generates strong electromagnetic interference, which may couple to the DI signal line, causing transient level glitches. To improve the reliability of contactor status feedback in energy storage systems and avoid transient misreadings caused by signal jitter and electromagnetic interference, the method provided in this application embodiment further includes: The status signal of the contactor auxiliary contact is acquired continuously for a preset number of times. When the status signals of the contactor auxiliary contact are all at the same level, the status signal of the contactor auxiliary contact is determined to be a valid signal.

[0058] Specifically, a continuous sampling number N is set (e.g., N=3, N=5, or N=10, which can be adjusted according to the system's requirements for response speed and anti-interference capability). The auxiliary contact's level signal is read once every equal sampling duration (e.g., 1 second, 2 seconds, etc.). (A high level indicates a closed contact, a low level indicates an open contact.) If the level signals collected N times consecutively are all at the same level, the auxiliary contact state is considered a valid signal. Only level states confirmed as "valid signals" will be used for subsequent contactor fault diagnosis. If the level signals collected N times consecutively are not completely consistent (at least one level is different), the signal is considered invalid, and the next sampling continues.

[0059] By sampling multiple times consecutively and ensuring all samples are consistent before a signal is considered valid, false states caused by jitter can be filtered out, effectively eliminating signal jitter and improving electromagnetic interference resistance. This ensures that the BCU only identifies stable and reliable state signals, thereby reducing false fault diagnosis.

[0060] Step S23: Calculate the pressure difference between the internal and external total pressures based on the internal total pressure and the external total pressure.

[0061] Based on the internal total pressure on the contactor battery side and the external total pressure on the contactor load side collected in step S22, the difference between the two is calculated to obtain the internal and external total pressure difference.

[0062] In actual operation, the voltage sampling channel is susceptible to electromagnetic interference, causing abnormal deviations in the instantaneous measurement values ​​of the internal or external total voltage. If the unprocessed raw voltage value is used directly to calculate the voltage difference, a brief abnormal jump may trigger false protection (such as a false alarm of incomplete contactor adhesion), leading to system shutdown or startup failure. Based on this, the method provided in this application embodiment further includes: Before calculating the pressure difference between the internal and external total pressures based on the internal and external total pressures. The internal and external total pressures are filtered to remove abnormal offset values.

[0063] Optionally, the internal total pressure and external total pressure can be filtered using methods such as amplitude limiting filtering, median filtering, and moving average filtering.

[0064] This application embodiment filters the internal total pressure and external total pressure before differential pressure calculation to eliminate abnormal offset values, avoid false protection caused by abnormal voltage sampling, improve the reliability of contactor status judgment, and thus reduce fault misjudgment.

[0065] Step S24: When the operating state is stationary, determine whether the contactor state is abnormal based on the status signal of the contactor auxiliary contact and the pressure difference between the internal and external total pressure.

[0066] When the energy storage system is in a static state, the BMS determines whether the contactor is in an abnormal state based on the status signal of the contactor auxiliary contacts and the pressure difference between the internal and external total pressure.

[0067] In some optional embodiments, the contactor state includes the contactor body state and the contactor connection state; determining whether the contactor state is abnormal based on the status signal of the contactor auxiliary contacts and the internal and external total pressure difference includes: If the status signal of the contactor's auxiliary contact is low and the total internal and external voltage difference is greater than the first preset threshold, then the contactor body is determined to be in an abnormal state, and the contactor connection is abnormal; or If the status signal of the auxiliary contact of the contactor is low and the total internal and external voltage difference is less than or equal to the first preset threshold, then the contactor body is determined to be in an abnormal state and the contactor connection is normal.

[0068] When the energy storage system is in a static state, the contactor should be in the open state, and the status signal of the contactor's auxiliary contact should be high. If the status signal of the contactor's auxiliary contact is low, the contactor body is considered abnormal; if the status signal of the contactor's auxiliary contact is high, the contactor body is considered normal. In this embodiment, the contactor is in the open state, the main circuit is disconnected, and the contactor connection status is not determined at this time. When the contactor is in the closed state (i.e., the status signal of the contactor's auxiliary contact is low, and the contactor body is abnormal), if the total internal and external voltage difference is greater than a first preset threshold (e.g., 1V, 2V, etc.), the contactor connection status is considered abnormal; if the total internal and external voltage difference is less than or equal to the first preset threshold, the contactor connection status is considered normal.

[0069] In the embodiments of this application, a voltage below 1V is represented as a low level, and a voltage above 3.3V is represented as a high level.

[0070] In this embodiment of the application, when the energy storage system is in a static state, the auxiliary contact level signal detection and the internal and external total pressure difference detection are used to detect not only the fault status of the contactor itself, but also the fault status of the contactor connection. This comprehensively diagnoses the overall status of the contactor, improves the accuracy and reliability of contactor fault detection, and reduces the missed and false alarms of contactor status faults.

[0071] Step S25: When the operating state is charging and discharging, obtain the branch current of the main contact of the contactor; determine whether the contactor state is abnormal based on the status signal of the auxiliary contact of the contactor, the voltage difference between the internal and external total voltage and the branch current of the main contact of the contactor.

[0072] When the energy storage system is in the charging and discharging state, the BMS determines whether the contactor is in an abnormal state based on the status signal of the contactor auxiliary contacts, the internal and external total voltage difference, and the branch current of the contactor main contacts.

[0073] In some optional embodiments, the contactor state includes the contactor body state and the contactor connection state; determining whether the contactor state is abnormal based on the status signal of the contactor auxiliary contacts, the internal and external total voltage difference, and the branch current of the contactor main contacts includes: If the status signal of the contactor's auxiliary contact is low, and the total voltage difference between the internal and external contacts is less than or equal to the first preset threshold, and the branch current of the contactor's main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor's auxiliary contact is low, and the total voltage difference between the internal and external contacts is less than or equal to the first preset threshold, and the branch current of the contactor's main contact is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor's auxiliary contact is low, the total voltage difference between the inside and outside is greater than the first preset threshold, and the branch current of the contactor's main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, but the contactor connection is abnormal; or If the status signal of the contactor's auxiliary contact is low, and the total internal and external voltage difference is greater than the first preset threshold, and the branch current of the contactor's main contact is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, but the contactor connection is abnormal; or If the status signal of the contactor's auxiliary contact is high, and the total voltage difference between the internal and external contacts is less than or equal to the first preset threshold, and the branch current of the contactor's main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor's auxiliary contact is high, and the total voltage difference between the internal and external contacts is less than or equal to the first preset threshold, and the branch current of the contactor's main contact is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor's auxiliary contact is high, and the total voltage difference between the internal and external contacts is greater than the first preset threshold, and the branch current of the contactor's main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, but the contactor connection is abnormal; or If the status signal of the auxiliary contact of the contactor is high, the voltage difference between the internal and external total voltages is greater than the first preset threshold, and the branch current of the main contact of the contactor is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is abnormal.

[0074] In this embodiment of the application, when the energy storage system is in the charging and discharging state, if the total internal and external pressure difference is greater than the first preset threshold, it is determined to be an abnormal pressure difference; if the total internal and external pressure difference is greater than the first preset threshold, it is determined to be an abnormal pressure difference; if the total internal and external pressure difference is less than or equal to the first preset threshold, it is determined to be a normal pressure difference. If the branch current of the contactor main contact is less than or equal to the second preset threshold (e.g., 1A), it is determined to be no current; if the branch current of the contactor main contact is greater than the second preset threshold, it is determined to be current.

[0075] The following are some of the main logic methods for determining whether a contactor is in an abnormal state, based on the status signals of the contactor's auxiliary contacts, the voltage difference between the internal and external total voltages, and the branch current of the contactor's main contacts: 1. Low level, normal voltage difference, current indicates that the contactor is closed, there is current in the main circuit, the voltage difference between the internal and external total voltage is very small, the external connection is firm, and the system is charging and discharging normally. Therefore, it is determined that the body status is normal and the connection status is normal. 2. Low level, normal voltage difference, no current indicates that the contactor is closed and the main circuit is connected, but there is currently no charging or discharging current. The normal voltage difference indicates that the contacts are conducting well and the external connection is normal. Therefore, the body status and connection status are normal. 3. Low level, abnormal voltage difference, current present indicates that the contactor is closed and current is flowing through it. The contactor body is normal, but the external connection is loose or oxidized. The contact resistance between the main contact and the copper busbar connection point is too high, resulting in a significant voltage drop under high current. The total voltage difference between the internal and external circuits is abnormal. Therefore, it is determined that the contactor body is normal, but the connection is abnormal. 4. Low level, abnormal voltage difference, no current indicates that the contactor is closed and the contactor itself is intact. However, due to the loose or broken external connection point, the main circuit is not connected (no current). The internal total voltage is normal, the external total voltage is low, and the voltage difference between the internal and external total voltages is abnormal. Therefore, it is determined that the contactor itself is in normal condition, but the connection condition is abnormal. 5. High level, normal differential pressure, and current indicate that the contactor is actually engaged (because current is flowing through it). When the contactor is engaged, the auxiliary contact should output a low level, but it outputs a high level. At this time, the high level is a signal that has been interfered with. The error in the auxiliary contact signal is an interference fault. The main body is still normal. The normal differential pressure indicates that the connection is normal. Therefore, it is determined that the main body is normal and the connection is normal. 6. High level, normal voltage difference, no current, indicates that the contactor has been disconnected, there is no current in the main circuit, the system is stopped, and both the internal total voltage and the external total voltage difference are 0. Therefore, it is determined that the body status is normal and the connection status is normal. 7. High level, abnormal voltage difference, current indicates that the contactor is actually engaged (because current is flowing through it). When the contactor is engaged, the auxiliary contact should output a low level, but it outputs a high level. At this time, the high level is a signal that has been interfered with. The error in the auxiliary contact signal is an interference fault. The main body is still normal. The abnormal voltage difference indicates an abnormal connection status. Therefore, it is determined that the main body status is normal and the connection status is normal. 8. High level, abnormal voltage difference, no current indicates that the contactor body is damaged (such as coil burnout, armature stuck), and the auxiliary contact itself is stuck in the open position (feedback high level), the main circuit is disconnected, there is no current, and the voltage difference is abnormal. Therefore, it is determined that the body state is abnormal and the connection state is abnormal.

[0076] In this embodiment of the application, when the energy storage system is in the charging and discharging state, the auxiliary contact level signal detection, the internal and external total voltage difference detection, and the current detection are used to not only detect the fault status of the contactor itself, but also to detect the fault status of the contactor connection. This comprehensively diagnoses the overall status of the contactor, improves the accuracy and reliability of contactor fault detection, and reduces the missed and false alarms of contactor status faults.

[0077] In summary, this application obtains the current operating status of the energy storage system. When the energy storage system is in a static state, the status of the contactor is determined based on the status signal of the contactor's auxiliary contacts and the internal and external total voltage difference. When the energy storage system is in a charging / discharging state, the status of the contactor is determined based on the status signal of the contactor's auxiliary contacts, the internal and external total voltage difference, and the branch current of the contactor's main contacts. This application differentiates fault detection by distinguishing the operating status of the energy storage system. In the static state, auxiliary contact and voltage difference detection are performed; in the charging / discharging state, auxiliary contact, voltage difference, and current detection are performed. This achieves multi-parameter fusion diagnosis, which helps to accurately match operating conditions, reduce false alarms and missed alarms of contactor status faults, improve the accuracy and reliability of contactor fault detection, reduce the failure rate of the energy storage system, and ensure the operational safety of the energy storage system.

[0078] In some optional implementations, the method provided in this application embodiment further includes: When both the contactor body status and the contactor connection status are normal, the control energy storage system will perform normal charging and discharging. When at least one of the contactor body state and contactor connection state is abnormal, the energy storage system is prohibited from charging and discharging.

[0079] By monitoring the contactor's physical and connection status separately, the energy storage system is allowed to perform normal charging and discharging operations when both are normal. When at least one of the physical or connection statuses is abnormal (including physical abnormality, connection abnormality, or both physical and connection abnormalities), the energy storage system is prohibited from charging and discharging. This effectively prevents the escalation of faults, improves system safety, and by distinguishing between "physical status" and "connection status," real-time diagnosis can be performed before charging and discharging begins or during operation, providing clear prohibition decisions. Maintenance personnel can quickly locate the root cause of the fault based on the reported abnormality type (physical abnormality or connection abnormality) without having to disassemble and troubleshoot one by one, significantly shortening fault handling time and reducing the total lifecycle maintenance cost.

[0080] In some optional implementations, the method provided in this application embodiment further includes: Obtain the temperature at the contactor connection point; Check if the temperature at the contactor connection is normal; If the temperature at the contactor connection is normal, the energy storage system will continue normal charging and discharging; or If the temperature at the contactor connection is abnormal, the energy storage system is prohibited from charging and discharging.

[0081] During normal operation, the BMS also monitors the temperature at the contactor connection (e.g., Figure 1 (See temperature measurement points 1 and 2 shown). If the temperature is abnormal (e.g., too high), it indicates that the connection point may have poor contact or excessive resistance, leading to overheating and an abnormal contactor connection. In this case, the energy storage system should be prohibited from charging and discharging, and alarms or shutdown protection can be triggered as needed to prevent thermal runaway. If the temperature is normal, the energy storage system is allowed to continue normal charging and discharging operations.

[0082] It should be noted that this application's embodiments incorporate temperature detection in addition to differential pressure detection, auxiliary contact level detection, and current detection. By cross-validating temperature information with other diagnostic information (level, differential pressure, and current), a multi-dimensional detection is formed, further improving the reliability of fault diagnosis. Simultaneously, due to the natural hysteresis of temperature signals, short-term, transient electrical fluctuations can be filtered out. For example, a brief differential pressure may occur during normal contactor operation, but this does not cause a significant temperature rise. In such cases, relying solely on electrical criteria might lead to false alarms of connection abnormalities, resulting in unnecessary shutdowns. Incorporating temperature information significantly reduces the false alarm rate and the number of unplanned shutdowns, improving the operational availability of the energy storage system.

[0083] In some optional implementations, determining whether the temperature at the contactor connection is normal includes: If the temperature at the contactor connection exceeds the temperature threshold, the temperature at the contactor connection is determined to be abnormal; or If the temperature at the contactor connection is less than or equal to the temperature threshold, the temperature at the contactor connection is considered normal.

[0084] For example, if the temperature at the contactor connection exceeds 70°C, the temperature at the contactor connection is determined to be abnormal; conversely, if the temperature at the contactor connection is less than or equal to 70°C, the temperature at the contactor connection is determined to be normal. In this embodiment, the temperature threshold can be set according to actual conditions, and this application does not impose any limitations.

[0085] Optionally, the temperature at the contactor connection is collected by a distributed temperature sensor array, which includes three independent temperature measuring nodes: the contactor inlet, the outlet, and the intermediate connection point of the copper busbar. When the maximum temperature difference between any two temperature measuring nodes is greater than 15°C, the temperature at the contactor connection is determined to be abnormal.

[0086] In this embodiment, a distributed temperature sensor array is used, with three temperature measurement nodes set at the contactor's inlet, outlet, and copper busbar connection points. An abnormal temperature at the connection is determined when the temperature difference between any two points exceeds 15°C. Compared to the single-point threshold method, firstly, the temperature difference criterion automatically offsets ambient temperature drift, eliminating the need for on-site calibration; secondly, heat generated by poor local contact can be quickly captured, enabling early warning; thirdly, the multi-node temperature monitoring design effectively suppresses false alarms from single sensors, improving system robustness; and fourthly, the temperature difference distribution pattern can accurately locate loose or oxidized nodes, shortening troubleshooting time and achieving highly sensitive, highly reliable, and calibration-free contactor connection status monitoring.

[0087] In other embodiments, the temperature at the contactor connection can be determined based on the rate of temperature change. For example, if the rate of temperature change is greater than a threshold within a certain period of time, it is considered abnormal; otherwise, it is considered normal.

[0088] In some optional implementations, when a first contactor is connected in parallel with the contactor, determining whether the temperature at the contactor connection is normal includes: Obtain the temperature at the connection point of the first contactor; Calculate the temperature difference between the contactor connection and the first contactor connection; If the difference is within the preset range, the temperature at the contactor connection is determined to be normal; or If the difference is not within the preset range, the temperature at the contactor connection is determined to be abnormal.

[0089] like Figure 1As shown, if fault diagnosis is to be performed on the main positive contactor KM1, it is necessary to obtain the temperature at the connection point of the main positive contactor KM1 (i.e., temperature measuring point 1). The main positive contactor KM1 is connected in parallel with the first contactor (i.e., the main negative contactor KM2), and the temperature at the connection point of the main negative contactor KM2 is obtained (i.e., temperature measuring point 2). The difference between the temperatures at temperature measuring point 1 and temperature measuring point 2 is calculated. If the difference is within a preset range (e.g., ±5℃), the temperature at the connection point of the main positive contactor KM1 is determined to be normal. If the difference is not within the preset range, the temperature at the connection point of the main positive contactor KM1 is determined to be abnormal.

[0090] In this embodiment, temperature measuring points are set at the connection points of two contactors operating in parallel, and the temperature difference between the two is calculated to determine whether the temperature is normal. When the difference is within a preset range, the contactor connection is considered normal; otherwise, it is considered abnormal. Utilizing the characteristics of parallel contactors operating in the same thermal environment and carrying similar currents, the temperature difference can automatically offset common-mode factors such as ambient temperature and load fluctuations. When the connection point of one contactor becomes loose or oxidized, increasing contact resistance, its localized heating will cause the temperature at that point to be significantly higher than that of the other contactor, thus enabling early and accurate diagnosis through exceeding the temperature difference limit. Simultaneously, the difference criterion reduces false alarms caused by drift or interference from a single sensor; an abnormality is only triggered when a true temperature difference exists between the two measuring points, significantly improving the reliability and robustness of fault detection.

[0091] In summary, the contactor fault diagnosis method provided in this application has the following technical effects: (1) Multi-dimensional comprehensive detection mechanism: Breaking through the traditional single auxiliary contact detection method, the four key parameters of contactor auxiliary contact status, system current, internal and external total pressure difference (comparison of cumulative total pressure and external total pressure) and connection point temperature are comprehensively detected to form a complete status judgment system.

[0092] (2) Distinguish between the body state and the connection state: It can not only detect the engagement / disengagement state of the contactor body, but also diagnose whether the contactor connection state is good, thus solving the problem that the connection state is not detected in related technologies.

[0093] (3) Anti-interference intelligent identification: When a high-level signal is detected from the auxiliary contact, but the system current and the voltage difference between the internal and external total voltages are normal, it is determined that this is a false alarm caused by external interference rather than a real fault, thus avoiding misjudgment.

[0094] (4) Real-time fault warning function: If an abnormal temperature is detected at the contactor connection point during the system charging and discharging process, the contactor connection fault alarm will be triggered immediately and the charging and discharging operation will be stopped to prevent the fault from escalating.

[0095] (5) Significantly improve reliability: Through multi-parameter cross-validation, the false alarm rate and false alarm rate of contactor status faults are greatly reduced, thereby improving the overall operational stability of the energy storage system.

[0096] This application embodiment also provides an energy storage system, including: a battery management system, the battery management system including a battery control unit, the battery control unit being used to collect the status signal of the contactor auxiliary contact, the internal total voltage on the contactor battery side, the external total voltage on the contactor load side, the branch current of the contactor main contact and the temperature at the contactor connection, the battery management system being used to acquire the signals collected by the battery control unit and execute the contactor fault diagnosis method as shown in the above embodiment.

[0097] Based on the same idea, this application also provides a fault diagnosis device for a contactor, such as... Figure 3 This is a schematic diagram of a contactor fault diagnosis device provided in an embodiment of this application. The contactor fault diagnosis device 30 mainly includes: The first acquisition module 31 is used to acquire the current operating status of the energy storage system, which is either a static state or a charging / discharging state. The second acquisition module 32 is used to acquire the status signal of the contactor auxiliary contact, the internal total voltage on the contactor battery side, and the external total voltage on the contactor load side. Calculation module 33 is used to calculate the pressure difference between the internal and external total pressures based on the internal total pressure and the external total pressure; The fault diagnosis module 34 is used to determine whether the contactor is in an abnormal state based on the status signal of the contactor auxiliary contacts and the pressure difference between the internal and external total pressure when the operating state is stationary. When the operating state is charging and discharging, the branch current of the contactor's main contacts is obtained; based on the status signal of the contactor's auxiliary contacts, the voltage difference between the internal and external total voltages, and the branch current of the contactor's main contacts, it is determined whether the contactor's state is abnormal.

[0098] In one possible implementation, the contactor state includes the contactor body state and the contactor connection state, and the fault diagnosis module 34 is further used for: If the status signal of the contactor's auxiliary contact is low and the total internal and external voltage difference is greater than the first preset threshold, then the contactor body is determined to be in an abnormal state, and the contactor connection is abnormal; or If the status signal of the auxiliary contact of the contactor is low and the total internal and external voltage difference is less than or equal to the first preset threshold, then the contactor body is determined to be in an abnormal state and the contactor connection is normal.

[0099] In one possible implementation, the contactor state includes the contactor body state and the contactor connection state, and the fault diagnosis module 34 is further used for: If the status signal of the contactor's auxiliary contact is low, and the total voltage difference between the internal and external contacts is less than or equal to the first preset threshold, and the branch current of the contactor's main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor's auxiliary contact is low, and the total voltage difference between the internal and external contacts is less than or equal to the first preset threshold, and the branch current of the contactor's main contact is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor's auxiliary contact is low, the total voltage difference between the inside and outside is greater than the first preset threshold, and the branch current of the contactor's main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, but the contactor connection is abnormal; or If the status signal of the contactor's auxiliary contact is low, and the total internal and external voltage difference is greater than the first preset threshold, and the branch current of the contactor's main contact is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, but the contactor connection is abnormal; or If the status signal of the contactor's auxiliary contact is high, and the total voltage difference between the internal and external contacts is less than or equal to the first preset threshold, and the branch current of the contactor's main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor's auxiliary contact is high, and the total voltage difference between the internal and external contacts is less than or equal to the first preset threshold, and the branch current of the contactor's main contact is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor's auxiliary contact is high, and the total voltage difference between the internal and external contacts is greater than the first preset threshold, and the branch current of the contactor's main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, but the contactor connection is abnormal; or If the status signal of the auxiliary contact of the contactor is high, the voltage difference between the internal and external total voltages is greater than the first preset threshold, and the branch current of the main contact of the contactor is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is abnormal.

[0100] In one possible implementation, the contactor fault diagnosis device 30 further includes a control module for: When both the contactor body status and the contactor connection status are normal, the control energy storage system will perform normal charging and discharging. When at least one of the contactor body state and contactor connection state is abnormal, the energy storage system is prohibited from charging and discharging.

[0101] In one possible implementation, the fault diagnosis device 30 for the contactor further includes: a third acquisition module for acquiring the temperature at the contactor connection point; The judgment module is used to determine whether the temperature at the contactor connection is normal. If the temperature at the contactor connection is normal, the energy storage system will continue normal charging and discharging; or If the temperature at the contactor connection is abnormal, the energy storage system is prohibited from charging and discharging.

[0102] In one possible implementation, the judgment module is also used for: If the temperature at the contactor connection exceeds the temperature threshold, the temperature at the contactor connection is determined to be abnormal; or If the temperature at the contactor connection is less than or equal to the temperature threshold, the temperature at the contactor connection is considered normal.

[0103] In one possible implementation, when the contactor is connected in parallel with a first contactor, the determination module is also used for: Obtain the temperature at the connection point of the first contactor; Calculate the temperature difference between the contactor connection and the first contactor connection; If the difference is within the preset range, the temperature at the contactor connection is determined to be normal; or If the difference is not within the preset range, the temperature at the contactor connection is determined to be abnormal.

[0104] In one possible implementation, the fault diagnosis device 30 for the contactor further includes: The determination module is used to continuously acquire the status signal of the contactor auxiliary contact a preset number of times. When the status signals of the contactor auxiliary contact are all at the same level, the status signal of the contactor auxiliary contact is determined to be a valid signal.

[0105] In one possible implementation, the fault diagnosis device 30 for the contactor further includes: The filtering module is used to filter the internal and external total pressures before calculating the pressure difference between the internal and external total pressures to remove abnormal offset values.

[0106] Figure 3 The contactor fault diagnosis device 30 provided in the illustrated embodiment can be used to execute the technical solution of the method embodiment shown in this application. Its implementation principle and technical effects can be further referred to the relevant description in the method embodiment.

[0107] The above should be understood Figure 3The division of the various modules in the fault diagnosis device 30 for the contactor shown is merely a logical functional division. In actual implementation, they can be fully or partially integrated into a single physical entity, or they can be physically separated. Furthermore, these modules can be implemented entirely in software via processing element calls; they can be fully implemented in hardware; or some modules can be implemented in software via processing element calls, while others are implemented in hardware. For example, the first acquisition module can be a separate processing element or integrated into a chip in the electronic device. The implementation of other modules is similar. In addition, these modules can be fully or partially integrated together, or implemented independently. During implementation, each step of the above method or each of the above modules can be completed through integrated logic circuits in the hardware of the processor element or through software instructions.

[0108] For example, these modules can be one or more integrated circuits configured to implement the above methods, such as one or more application-specific integrated circuits (ASICs), one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs). Alternatively, these modules can be integrated together as a system-on-a-chip (SOC).

[0109] In the above embodiments, the processor may include, for example, a CPU, DSP, microcontroller, or digital signal processor, and may also include a GPU, embedded neural network processing unit (NPU), and image signal processor (ISP). The processor may also include necessary hardware accelerators or logic processing hardware circuits, such as an ASIC, or one or more integrated circuits for controlling the execution of the program in this application. Furthermore, the processor may have the function of operating one or more software programs, which may be stored in a storage medium.

[0110] Those skilled in the art will recognize that the units and algorithm steps described in the embodiments disclosed herein can be implemented using electronic hardware, computer software, or a combination of electronic hardware and software. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0111] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0112] In the several embodiments provided in this application, any function, if implemented as a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0113] The above description is merely a specific embodiment of this application. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application. The protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A fault diagnosis method for a contactor, characterized in that, The method includes: Obtain the current operating status of the energy storage system, wherein the operating status is either a static state or a charging / discharging state; Acquire the status signals of the contactor auxiliary contacts, the internal total voltage on the contactor battery side, and the external total voltage on the contactor load side; Calculate the pressure difference between the internal and external total pressures based on the internal total pressure and the external total pressure. When the operating state is a stationary state, the state of the contactor is determined to be abnormal based on the status signal of the contactor auxiliary contact and the pressure difference between the internal and external total pressure. When the operating state is charging and discharging, the branch current of the contactor main contact is obtained; based on the status signal of the contactor auxiliary contact, the voltage difference between the internal and external total voltage and the branch current of the contactor main contact, it is determined whether the contactor state is abnormal.

2. The method according to claim 1, characterized in that, The contactor status includes the contactor body status and the contactor connection status; the method of determining whether the contactor status is abnormal based on the status signal of the contactor auxiliary contacts and the internal and external total pressure difference includes: If the status signal of the contactor auxiliary contact is low and the total internal and external voltage difference is greater than a first preset threshold, then the contactor body is determined to be in an abnormal state, and the contactor connection is abnormal; or If the status signal of the auxiliary contact of the contactor is low and the total internal and external voltage difference is less than or equal to the first preset threshold, then the contactor body is determined to be in an abnormal state and the contactor connection state is normal.

3. The method according to claim 1, characterized in that, The contactor status includes the contactor body status and the contactor connection status; the method of determining whether the contactor status is abnormal based on the status signal of the contactor auxiliary contacts, the internal and external total voltage difference, and the branch current of the contactor main contacts includes: If the status signal of the contactor auxiliary contact is low, and the total internal and external voltage difference is less than or equal to a first preset threshold, and the branch current of the contactor main contact is greater than a second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor auxiliary contact is low, and the total internal and external voltage difference is less than or equal to the first preset threshold, and the branch current of the contactor main contact is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor auxiliary contact is low, and the total internal and external voltage difference is greater than the first preset threshold, and the branch current of the contactor main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is abnormal; or If the status signal of the auxiliary contact of the contactor is low, and the total internal and external voltage difference is greater than the first preset threshold, and the branch current of the main contact of the contactor is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is abnormal.

4. The method according to claim 3, characterized in that, The method of determining whether the contactor status is abnormal based on the status signal of the contactor auxiliary contacts, the total internal and external voltage difference, and the branch current of the contactor main contacts further includes: If the status signal of the contactor auxiliary contact is high, and the total voltage difference between the internal and external contacts is less than or equal to the first preset threshold, and the branch current of the contactor main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor auxiliary contact is high, and the total internal and external voltage difference is less than or equal to the first preset threshold, and the branch current of the contactor main contact is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is normal; or If the status signal of the contactor auxiliary contact is high, and the total internal and external voltage difference is greater than the first preset threshold, and the branch current of the contactor main contact is greater than the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is abnormal; or If the status signal of the auxiliary contact of the contactor is high, and the voltage difference between the internal and external total voltages is greater than the first preset threshold, and the branch current of the main contact of the contactor is less than or equal to the second preset threshold, then the contactor body is determined to be in normal condition, and the contactor connection is abnormal.

5. The method according to claim 3 or 4, characterized in that, The method further includes: When both the contactor body status and the contactor connection status are normal, the control energy storage system will perform normal charging and discharging. When at least one of the contactor body state and contactor connection state is abnormal, the energy storage system is prohibited from charging and discharging.

6. The method according to claim 5, characterized in that, The method further includes: Obtain the temperature at the contactor connection point; Determine whether the temperature at the contactor connection is normal; If the temperature at the contactor connection is normal, the energy storage system will continue normal charging and discharging; or If the temperature at the contactor connection is abnormal, the energy storage system is prohibited from charging and discharging.

7. The method according to claim 6, characterized in that, The step of determining whether the temperature at the contactor connection is normal includes: If the temperature at the contactor connection exceeds a temperature threshold, the temperature at the contactor connection is determined to be abnormal; or If the temperature at the contactor connection is less than or equal to the temperature threshold, then the temperature at the contactor connection is determined to be normal.

8. The method according to claim 6, characterized in that, When a first contactor is connected in parallel with a contactor, determining whether the temperature at the contactor connection point is normal includes: Obtain the temperature at the connection point of the first contactor; Calculate the temperature difference between the contactor connection and the first contactor connection; If the difference is within a preset range, the temperature at the contactor connection is determined to be normal; or If the difference is not within the preset range, the temperature at the contactor connection is determined to be abnormal.

9. The method according to claim 1, characterized in that, The method further includes: The status signal of the contactor auxiliary contact is acquired a preset number of times. When the status signals of the contactor auxiliary contact are all at the same level, the status signal of the contactor auxiliary contact is determined to be a valid signal.

10. The method according to claim 1, characterized in that, Before calculating the pressure difference between the internal and external total pressures based on the internal total pressure and the external total pressure, the method further includes: The internal total pressure and the external total pressure are filtered to remove abnormal offset values.

11. A fault diagnosis device for a contactor, characterized in that, include: The first acquisition module is used to acquire the current operating status of the energy storage system, wherein the operating status is either a static state or a charging / discharging state. The second acquisition module is used to acquire the status signal of the contactor auxiliary contact, the internal total voltage on the contactor battery side, and the external total voltage on the contactor load side. The calculation module is used to calculate the pressure difference between the internal and external total pressures based on the internal total pressure and the external total pressure. The fault diagnosis module is used to determine whether the contactor is in an abnormal state based on the status signal of the contactor auxiliary contact and the pressure difference between the internal and external total pressure when the operating state is a stationary state. When the operating state is charging / discharging state, obtain the branch current of the contactor's main contacts; The status of the contactor is determined based on the status signal of the auxiliary contact, the total internal and external voltage difference, and the branch current of the main contact.

12. An energy storage system, characterized in that, include: A battery management system, comprising a battery control unit, wherein the battery control unit is used to collect status signals of the contactor auxiliary contacts, the internal total voltage on the contactor battery side, the external total voltage on the contactor load side, the branch current of the contactor main contacts, and the temperature at the contactor connection point; the battery management system is used to acquire the signals collected by the battery control unit and execute the contactor fault diagnosis method as described in any one of claims 1-10.

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