High-voltage power-on method and system for energy storage system

Abstract

The invention relates to the technical field of vehicle energy storage systems, and provides a high-voltage power-on method and system for an energy storage system. The method comprises the following steps: in response to a wake-up signal, executing a self-check operation to determine a battery fault level; if the battery meets the high-voltage power-on condition, passing judgment is carried out on a received high-voltage power-on signal of an energy storage energy management system (EMS); if the high-voltage power-on signal of the EMS passes, a negative relay and a pre-charging relay are controlled to be attracted to start a pre-charging process, and whether pre-charging is overtime or not is judged in the pre-charging process; if the pre-charging process is not overtime and the PCS end voltage reaches the preset proportion of the real-time total voltage of the battery, controlling to pull in a positive pole relay, and judging whether the state of a high-voltage loop is normal or not based on the difference value between the PCS end voltage and the real-time total voltage of the battery; and if the state of the high-voltage loop is normal, the pre-charging relay is controlled to be disconnected to complete high-voltage power-on. Adhesion caused by repeated suction breaking of the relay is avoided, and it is ensured that parts of a high-voltage loop are not damaged in the power-on process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle energy storage systems, in particular to a high-voltage power-on method and system for an energy storage system. BACKGROUND

[0002] Energy storage refers to the process of storing energy through a medium or device and releasing it when needed. Through flexible charging and discharging control, energy storage realizes the matching of energy production and consumption in time and space, and is an important technology and basic equipment to support new power systems. An energy storage system is composed of energy storage units (lithium battery clusters, BMS, high-voltage relays, etc.), PCS, EMS, TMS, fire-fighting and electrical units, etc., and can provide peak regulation, frequency regulation, backup, black start, demand response support and other services for power grid operation.

[0003] The energy storage unit is composed of a plurality of lithium batteries connected in series and in parallel, with a voltage of several hundred volts or even thousands of volts, which is a high-voltage component. A reasonable high-voltage power-on process and method are needed to ensure the safety of the energy storage system. Otherwise, an unreasonable high-voltage power-on method may affect the operating efficiency of the energy storage system, or even damage the high-voltage relays and cause safety accidents of the energy storage system and maintenance personnel.

[0004] The current disclosed high-voltage power-on technical solution for an energy storage system is that after the BMS is woken up, it receives the power-on instruction from the EMS, first attracts the negative electrode, and pre-charges the pre-charging relay. When the BMS detects that the difference between the terminal voltage of the PCS or AC and the total voltage of the battery cluster is lower than a certain value, the BMS attracts the positive electrode relay and disconnects the pre-charging relay to complete the high-voltage power-on. It can be seen that the pre-charging action after the BMS is woken up is single in execution judgment, only the power-on instruction from the EMS is considered, and the situations such as battery and other system faults, EMS instruction fluctuations or abnormalities are not considered. These situations may cause the relays to be repeatedly attracted and disconnected and stuck. Therefore, a more reliable high-voltage power-on method is needed to avoid the relays being repeatedly attracted and disconnected and stuck. SUMMARY

[0005] Therefore, the embodiments of the present application provide a high-voltage power-on method and system for an energy storage system, which can realize a more reliable high-voltage power-on method, avoid the relays being repeatedly attracted and disconnected and stuck, ensure that the components in the high-voltage loop are not damaged during the power-on process, and complete the high-voltage power-on on the basis of ensuring system and personnel safety.

[0006] A first aspect of the embodiments of the present application provides a high-voltage power-on method for an energy storage system, which is executed by a battery management system (BMS). The method comprises: performing a self-checking operation in response to a wake-up signal to determine a battery fault level, wherein the battery fault level is used to determine whether the battery meets a high-voltage power-on condition; If the battery meets the high-voltage power-on conditions, then the high-voltage power-on signal received from the energy storage management system (EMS) is judged to pass the test. If the high-voltage power-on signal of the EMS passes, the negative relay and the pre-charge relay are activated to start the pre-charge process, and the pre-charge process is checked to determine whether the pre-charge has timed out. If the pre-charging process does not time out and the PCS terminal voltage reaches a predetermined proportion of the battery's real-time total voltage, then the positive relay is activated, and the status of the high-voltage circuit is determined based on the difference between the PCS terminal voltage and the battery's real-time total voltage. If the high-voltage circuit is in normal condition, the pre-charge relay will be disconnected to complete the high-voltage power-on.

[0007] In one embodiment, determining whether the battery meets the high-voltage power-on conditions includes: When the battery fault level is a fault level that allows the battery to be powered on at high voltage, it is determined that the battery meets the conditions for high voltage power-on. When the battery fault level is a fault level that does not allow the battery to be powered on at high voltage, it is determined that the battery meets the condition of not being powered on at high voltage. The battery fault levels include at least fault levels that allow the battery to be powered at high voltage and fault levels that do not allow the battery to be powered at high voltage.

[0008] In one embodiment, the step of determining whether the received high-voltage power-on signal from the energy storage management system (EMS) passes the test includes: Based on the PCS high-voltage circuit power-on command, the energy storage system fault level, and the AC high-voltage circuit power-on command, the EMS high-voltage power-on signal is sequentially assessed for integrity, authenticity, and fault level.

[0009] In one embodiment, the integrity determination includes: If the PCS high-voltage circuit power-on command and the energy storage system fault level are received simultaneously, and the AC high-voltage circuit power-on command is received within a predetermined time, then the integrity judgment is determined to be successful. If the PCS high-voltage circuit power-on command and the energy storage system fault level are not received simultaneously, or if the AC high-voltage circuit power-on command is not received within a predetermined time period, then the integrity judgment is determined to be unsuccessful.

[0010] In one embodiment, the authenticity verification includes: Perform CRC verification on the received high-voltage power-on signal of the EMS; If the CRC check passes, then the authenticity determination is considered successful.

[0011] In one embodiment, the fault level determination includes: Obtain the fault level of the energy storage system; If the fault level of the energy storage system is lower than the preset fault level, then the fault level determination is passed; If the fault level of the energy storage system is not lower than the preset fault level, then the fault level judgment is determined to be unsuccessful.

[0012] 7. The high-voltage power-on method for an energy storage system as described in claim 1, characterized in that, determining whether the pre-charging timeout has occurred during the pre-charging process includes: If the BMS fails to report a timeout fault in sending the AC high-voltage circuit power-on command, then based on formula t t =(R PC +R B )×(C PCS +C AC )×ln(U B / (U B -U PCS )) Calculate the theoretical precharge time; If the BMS reports a timeout fault in the AC high-voltage circuit power-on command transmission, then based on formula t t =(R PC +R B )×C PCS ×ln(U B / (U B -U PCS )) Calculate the theoretical precharge time; If the precharge duration exceeds the theoretical precharge duration, then a precharge timeout is determined. Among them, t t For the theoretical pre-charge duration, R PC R is the pre-charge resistance value. B C represents the real-time internal resistance of the battery. PCS For PCS capacitance value, C AC For AC capacitance, U B U represents the real-time total battery voltage. PCS This refers to the voltage at the PCS terminal.

[0013] In one embodiment, determining whether the high-voltage circuit is in normal condition based on the difference between the PCS terminal voltage and the real-time total battery voltage includes: Calculate the difference between the PCS terminal voltage and the real-time total voltage of the battery; If the difference does not exceed the preset voltage threshold, the high-voltage circuit is determined to be in normal condition. If the difference exceeds the preset voltage threshold, the high-voltage circuit is determined to be in an abnormal state.

[0014] In one embodiment, the predetermined ratio is 95%.

[0015] A second aspect of this application provides an energy storage system, including a battery cell, an energy storage converter (PCS), an energy storage management system (EMS), and a battery management system (BMS), wherein the battery management system (BMS) is used to perform the method described in any of the above embodiments.

[0016] The high-voltage power-on method for energy storage systems provided in the first aspect of this application decomposes the continuous process of high-voltage power-on into multiple controllable and monitorable safety steps by establishing a multi-stage, multi-condition judgment process. Each step is a prerequisite for the next step, forming a chain-like safety protection. This effectively avoids malfunctions caused by the failure of a single judgment condition or abnormal commands, greatly improves the reliability and safety of the high-voltage power-on process of the energy storage system, significantly reduces the risk of high-voltage relay arcing and sticking, and ensures the safety of equipment and personnel.

[0017] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart of a high-voltage power-on method for an energy storage system provided in an embodiment of this application; Figure 2 This is a schematic flowchart of a high-voltage power-on method for an energy storage system provided in another embodiment of this application; Figure 3 This is a schematic diagram of a process for determining the BMS high-voltage power-on signal from a specific embodiment of this application. Figure 4 This is a schematic diagram of a process for determining the state of a high-voltage precharge to high-voltage circuit according to an embodiment of this application. Detailed Implementation

[0020] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0021] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0022] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0023] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0024] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0026] like Figure 1 As shown, the high-voltage power-on method for an energy storage system provided in this application embodiment is executed by the battery management system (BMS) and includes the following steps S101 to S106: Step S101: In response to the wake-up signal, perform a self-test operation to determine the battery fault level, wherein the battery fault level is used to determine whether the battery meets the high voltage power-on conditions. Step S102: If the battery meets the high-voltage power-on conditions, then the high-voltage power-on signal received from the energy storage management system (EMS) is judged. Step S103: If the high voltage power-on signal of the EMS passes, control the activation of the negative relay and the pre-charge relay to start the pre-charge process, and determine whether the pre-charge has timed out during the pre-charge process; Step S104: If the pre-charging process does not time out and the PCS terminal voltage reaches a predetermined proportion of the real-time total battery voltage, then control the positive relay to engage, and determine whether the high-voltage circuit status is normal based on the difference between the PCS terminal voltage and the real-time total battery voltage. Step S105: If the high-voltage circuit is in normal condition, the pre-charge relay is disconnected to complete the high-voltage power-on.

[0027] In application, the self-test operation in response to the wake-up signal refers to the self-diagnostic program that the Battery Management System (BMS) immediately initiates after switching from low-power sleep mode to normal operation mode. The core of the self-test operation is the comprehensive collection of various real-time parameters of the battery system, including but not limited to the total battery voltage, the voltage of each individual cell, the battery temperature distribution, the battery insulation resistance value, and the estimated state of charge (SOC). The BMS compares these collected parameter values ​​with pre-stored fault judgment thresholds to determine the current fault level of the battery. The battery fault level is an indicator used to quantify the battery's safety status. Referring to the vehicle alarm levels defined in the national standard GB / T 32960.3-2015, it is divided into levels 0 to 3, where level 0 represents no fault, level 1 represents a fault that does not affect normal battery use, level 2 represents a fault that allows high-voltage power-on but restricts battery use, and level 3 represents a fault that prohibits high-voltage power-on and prohibits battery use. The purpose of this step is to eliminate potential safety hazards inherent in the battery itself at the beginning of the high-voltage power-on process, laying a safe foundation for subsequent operations.

[0028] In application, if the battery meets the high-voltage power-on conditions, the high-voltage power-on signal pass-through judgment means that once the BMS confirms through self-test that the battery fault level is no higher than level 2, thus meeting the power-on conditions, it shifts from internal status monitoring to command interaction with the external Energy Management System (EMS). The EMS's high-voltage power-on signal is not a single command, but a set of commands including PCS high-voltage circuit power-on commands, AC high-voltage circuit power-on commands, and energy storage system fault level information. Pass-through judgment means the BMS needs to perform a series of rigorous checks on this command set, including checking whether the commands were delivered completely and without error, whether the commands were tampered with or erroneous during transmission, and whether the overall energy storage system status carried by the commands allows for power-on. This process ensures that the power-on decision is not only based on the battery's own state but also fully considers the operating status of other key components in the energy storage system, such as the PCS and AC, avoiding blindly executing high-voltage power-on when there are potential risks in the system.

[0029] In application, if the high-voltage power-on signal passes, the control to start the pre-charge process and determine whether the pre-charge has timed out means that after the EMS command passes all verifications, the BMS first controls the negative relay to engage to provide a common reference for the high-voltage circuit. Then, instead of directly engaging the positive relay, the pre-charge relay is engaged. Current flows through a current-limiting resistor, the pre-charge resistor, to charge the capacitor at the load end, thereby limiting the inrush current within a safe range. Determining whether the pre-charge has timed out is a critical safety point at this stage. The BMS dynamically calculates a theoretical pre-charge time threshold based on circuit parameters such as battery voltage, load capacitance, and pre-charge resistor value, and starts a timer. If the actual pre-charge time exceeds this threshold but the PCS voltage still does not reach the expected value, it is determined that the pre-charge has timed out, indicating that there may be an abnormality such as an open circuit or poor contact in the pre-charge circuit. The BMS will terminate the power-on process and report an error. This mechanism effectively prevents arcing damage to the positive relay when it engages with a large voltage difference due to pre-charge failure.

[0030] In application, if pre-charging is successful, the control to engage the positive relay and determine the high-voltage circuit status means that when the PCS terminal voltage is pre-charged to a predetermined ratio, such as 95%, of the total battery voltage, it indicates that the load capacitor is basically fully charged and the voltage difference is very small. At this time, the BMS controls the engagement of the positive relay, and the high-voltage main circuit is officially connected. To ensure reliable connection without any loose connections, the BMS will immediately detect the difference between the PCS terminal voltage and the total battery voltage. If this difference is within a very small preset voltage threshold, such as 1V, it indicates that the main circuit connection impedance is extremely small and the status is normal. If the difference is too large, it indicates that there may be abnormalities such as the relay sticking and not engaging or excessive line contact resistance.

[0031] In application, if the high-voltage circuit is in normal condition, the control to disconnect the pre-charge relay to complete the high-voltage power-on means that after the main circuit is confirmed to be normal, the pre-charge relay and its series current-limiting resistor will only waste energy and may burn out the resistor if they remain in the energized state. Therefore, the BMS will control the disconnection of the pre-charge relay so that the current can flow through the main circuit composed of the positive and negative relays. At this point, the high-voltage power-on process of the energy storage system is completed safely, and the system enters the standby or normal operation state.

[0032] Specifically, after the BMS is woken up, it first performs a self-test. If a level 3 battery fault is found, the process is aborted. If the fault level is level 2 or below, it waits to receive an EMS command. The BMS checks whether it has received the PCS power-on command, the AC power-on command, and the system fault level simultaneously. If the AC command times out and is not received, the fault is recorded but the process continues. Then, the received command data is checked using CRC verification, and the system fault level is checked to see if it is less than level 3. If any judgment fails, the process is aborted. If the judgment passes, the BMS engages the negative terminal and the pre-charge relay to start pre-charging. At the same time, it selects different capacitor values ​​based on whether the AC command is received to calculate the theoretical pre-charge time and keeps track of it. If the timeout occurs, an error is reported and the process is aborted. If the pre-charge is successful, the positive terminal relay is engaged, and the voltage difference between the two terminals is compared. If the difference is greater than 1V, an error is reported and all relays are disconnected. If the difference is less than or equal to 1V, the pre-charge relay is disconnected, and the power-on is complete.

[0033] Battery fault levels can be classified according to the vehicle alarm levels defined in the national standard GB / T32960.3-2015, and different voltage and temperature thresholds can also be customized according to the battery chemistry system, such as ternary lithium or lithium iron phosphate. High-voltage power-on signals can be transmitted via CAN bus, or industrial communication protocols such as RS485 or Ethernet.

[0034] This application embodiment decomposes the continuous process of high-voltage power-on into multiple controllable and monitorable safety steps by establishing a multi-stage, multi-condition judgment process. Each step is a prerequisite for the next step, forming a chain-like safety protection. This effectively avoids malfunctions caused by the failure of a single judgment condition or abnormal command, greatly improves the reliability and safety of the high-voltage power-on process of the energy storage system, significantly reduces the risk of high-voltage relay arcing and sticking, and ensures the safety of equipment and personnel.

[0035] In one embodiment, determining whether the battery meets the high-voltage power-on conditions includes: When the battery fault level is a fault level that allows the battery to be powered on at high voltage, it is determined that the battery meets the conditions for high voltage power-on. When the battery fault level is a fault level that does not allow the battery to be powered on at high voltage, it is determined that the battery meets the condition of not being powered on at high voltage. The battery fault levels include at least fault levels that allow the battery to be powered at high voltage and fault levels that do not allow the battery to be powered at high voltage.

[0036] In applications, determining whether the battery fault level meets the condition means that after the BMS completes its self-test, its internal logic unit compares the diagnosed real-time fault level with the preset allowed power-on threshold. Allowed power-on fault levels typically include level 0 (no fault), and levels 1 and 2 (minor abnormalities that do not affect basic safety functions). For example, the battery cell voltage may slightly deviate from the normal range but not reach the danger threshold, or the battery temperature may be slightly high but still within the allowed operating window. Determining that the condition is met means that the BMS's logic output changes from a waiting or disabled state to an enabled state, granting permission to execute subsequent instruction judgment steps.

[0037] In application, determining that the condition is not met when the battery fault level is a level that does not allow the battery to be powered on at high voltage means that when the BMS diagnoses a level 3 fault in the battery, such as a serious insulation fault, a serious overvoltage or undervoltage of the battery total voltage, or a single cell temperature exceeding the safety limit, the BMS will immediately determine that the high-voltage power-on condition is not met. At this time, the BMS will not only stop all subsequent power-on processes, but will also usually trigger an alarm signal and report the specific fault type and level information to the EMS or local display so that maintenance personnel can handle it in a timely manner. This mechanism ensures that the battery is absolutely prohibited from being connected to the high-voltage system when there is a serious safety risk.

[0038] Specifically, the BMS has a pre-stored mapping table between fault levels and power-on permissions. After the self-test program runs, the processor matches the real-time fault level with the table. If the matching result is level 0, level 1, or level 2, a logic high-level power-on permission flag is generated. If the matching result is level 3, a logic low-level power-on prohibition flag is generated, and the corresponding fault code may be set. Subsequent processes will only continue to execute when the power-on permission flag is detected to be valid.

[0039] The fault level for allowing high-voltage power-on of the battery can be divided into three levels (0, 1, 2) or a simpler two-level division, distinguishing only between allowing power-on and prohibiting power-on. Determining whether the battery meets the high-voltage power-on conditions can be achieved using a simple logic comparator circuit or software judgment statements within the microcontroller.

[0040] In application, referring to the fault types defined in the national standard GB / T 32960.3-2015, and considering battery performance, common battery fault items and judgment conditions are shown in Tables 1-3 below: Table 1 Common Level 1 Battery Faults Table 2 Common Battery Level 2 Faults Table 3 Common Battery Level 3 Faults The BMS determines the battery fault level. If the battery fault level is level 3, the high-voltage power-on condition is not met and the fault level needs to be downgraded. If the battery fault level is level 2 or below, the BMS self-test is passed and the EMS high-voltage power-on signal judgment stage is entered.

[0041] This application explicitly uses the battery fault level as a prerequisite for high-voltage power-on, establishing a strong correlation between the battery's own health status and the system's high-voltage operation. This design ensures that even if the external command is normal, the high-voltage power-on process cannot proceed if the battery itself has a serious fault. This avoids extreme safety accidents such as thermal runaway that may be caused by putting a faulty battery into operation, thereby improving the inherent safety level of the system.

[0042] In one embodiment, the step of determining whether the received high-voltage power-on signal from the energy storage management system (EMS) passes the test includes: Based on the PCS high-voltage circuit power-on command, the energy storage system fault level, and the AC high-voltage circuit power-on command, the EMS high-voltage power-on signal is sequentially assessed for integrity, authenticity, and fault level.

[0043] In application, based on the PCS high-voltage circuit power-on command, the energy storage system fault level, and the AC high-voltage circuit power-on command, these are three key information units that the BMS expects to receive from the EMS. The PCS high-voltage circuit power-on command is an instruction issued by the EMS to the BMS allowing the battery cluster to supply power to the DC side of the PCS. The AC high-voltage circuit power-on command is an instruction allowing power to be supplied to the AC side, such as transformers or loads. The energy storage system fault level is the comprehensive assessment result of the EMS on the status of external systems such as the PCS, TMS, and fire protection. These three signals together constitute the EMS's comprehensive judgment on whether the overall energy storage system meets the conditions for high-voltage power-on.

[0044] In application, the sequential integrity check, authenticity verification, and fault level determination of the EMS high-voltage power-on signal refer to the logical order in which the BMS processes these three signals. Integrity check is the first step, ensuring that all required signals have been received without omission. Authenticity verification is the second step, ensuring that the received signal data has not been erroneous or tampered with during transmission. Fault level determination is the final step, confirming whether the system status allows power-on from a content perspective. This sequential arrangement optimizes processing efficiency because integrity check is the fastest and can immediately detect obvious problems such as communication interruptions. Authenticity verification requires a certain amount of computation, while fault level determination is the final application of valid data.

[0045] Specifically, the BMS communication module receives data frames from the EMS sequentially. First, it checks whether the buffer contains data packets identified as PCS power-on command, AC power-on command, and system fault level. If all are present, it proceeds to the next step. Subsequently, the BMS processor performs a CRC32 checksum algorithm on the payload of these three data packets and compares the calculation result with the checksum carried in the data packet. If the comparison is successful, the value is finally extracted from the system fault level data packet to determine whether it is less than the preset power-on prohibition threshold of 3.

[0046] Integrity assessment can be achieved by checking whether a specific message identifier appears in the receive queue within a specified time, or by checking whether the number of received data packets meets the expected value. Fault level assessment can be achieved by comparing the received fault level value with a fixed threshold, or by comparing it with a dynamically changing threshold range.

[0047] This application embodiment defines the EMS command judgment process as three distinct sub-steps, forming a triple security verification mechanism from the communication link to the data content. This structured approach avoids the limitations of a single judgment condition. Integrity judgment prevents malfunctions caused by signal loss, authenticity verification resists transmission interference or malicious attacks, and fault level judgment ensures the state security of the system level, greatly enhancing the accuracy and robustness of high-voltage power-on decisions.

[0048] In one embodiment, the integrity determination includes: If the PCS high-voltage circuit power-on command and the energy storage system fault level are received simultaneously, and the AC high-voltage circuit power-on command is received within a predetermined time, then the integrity judgment is determined to be successful. If the PCS high-voltage circuit power-on command and the energy storage system fault level are not received simultaneously, or if the AC high-voltage circuit power-on command is not received within a predetermined time period, then the integrity judgment is determined to be unsuccessful.

[0049] In application, if the PCS high-voltage circuit power-on command and the energy storage system fault level are received simultaneously, and the AC high-voltage circuit power-on command is received within a predetermined time, the integrity judgment is considered passed. This refers to the BMS's specific requirements for signal integrity. The PCS command and the system fault level are the core necessary commands for high-voltage power-on, and the process can only continue if they are received simultaneously. The AC command may not be necessary in some operating modes, so a predetermined grace period is given, such as 3 EMS communication cycles. If it is received within this period, it is considered complete. This requirement balances the system's strictness and flexibility.

[0050] In application, if the PCS high-voltage circuit power-on command and the energy storage system fault level are not received simultaneously, or if the AC high-voltage circuit power-on command is not received within the predetermined time, the integrity judgment is determined to fail. This means that the judgment will fail if any integrity condition is not met. The failure to receive the core command at the same time indicates that the EMS may not have sent normally or there may be a serious problem with the communication link. The AC command reception timeout is recorded as a non-serious fault, but the process can still continue. This distinction clearly defines the fault priority.

[0051] Specifically, the BMS has an internal timer. When integrity checking begins, the timer starts, and the BMS checks the data receive buffer. If the timestamps of the PCS command and the system fault level data packets are very close, it is determined that they were received simultaneously. The BMS then continues to wait for the AC command. If the AC command is received before the timer expires, the integrity is considered successful. If the timer overflows and the AC command is still not received, the BMS records an AC command timeout fault, but still determines that the integrity is successful so that it can proceed to subsequent verification. If neither the PCS command nor the system fault level data is received simultaneously, the integrity is immediately determined to fail and an error is reported.

[0052] The predetermined duration can be a fixed value, such as 100 milliseconds, or a dynamic value that is an integer multiple of the EMS communication cycle. The integrity check can be performed by setting a status flag in software, or by using hardware logic gates to output high or low levels.

[0053] The embodiments of this application precisely quantify the integrity judgment, which not only ensures the reliability of the basic instructions necessary for high-voltage power-on, but also sets up a fault-tolerant mechanism for the abnormality of non-essential instructions, avoiding the failure of the entire system's high-voltage power-on function due to a single non-critical signal abnormality, and improving the availability and resilience of the system under non-ideal communication conditions.

[0054] In one embodiment, the authenticity verification includes: Perform CRC verification on the received high-voltage power-on signal of the EMS; If the CRC check passes, then the authenticity determination is considered successful.

[0055] In applications, performing CRC verification on the received high-voltage power-on signal of the EMS refers to Cyclic Redundancy Check, which is a method of detecting data errors through polynomial division. After the EMS sends data at the sending end, the BMS will use the same CRC generating polynomial to recalculate a check value for the received data content.

[0056] In application, if the CRC check passes, the authenticity is confirmed. This means that the BMS compares the check value it calculates with the check code at the end of the data frame. If the two values ​​are exactly the same, it means that there is a very high probability that no bit transitions occurred during the data transmission, that is, the data is authentic and reliable, and the BMS then allows the process to proceed to the next judgment stage.

[0057] Specifically, the BMS communication processor reads the data portion of the high-voltage power-on command from the receive buffer, excluding the frame header and the checksum itself. It then treats this as a very long binary number and performs a modulo-2 division operation with a preset CRC32 polynomial to obtain a remainder. This remainder is the calculated local checksum value. Subsequently, the BMS compares the local checksum value bit by bit with the checksum byte attached to the data frame. If they match completely, the checksum passes.

[0058] CRC checksums can use the standard CRC16 polynomial, or even more complex CRC32C polynomials. Verification of received signals can be performed using CRC checksums, parity checks, checksums, or more secure cryptographic hash functions such as MD5 and SHA1.

[0059] This application embodiment introduces CRC check, a mature communication verification technology, to effectively ensure the authenticity of high-voltage power-on commands. It can identify data errors caused by noise interference, signal attenuation, etc. during transmission, prevent the BMS from executing dangerous high-voltage operations based on erroneous commands, and improve the anti-interference capability and system security of the command transmission link.

[0060] In one embodiment, the fault level determination includes: Obtain the fault level of the energy storage system; If the fault level of the energy storage system is lower than the preset fault level, then the fault level determination is passed; If the fault level of the energy storage system is not lower than the preset fault level, then the fault level judgment is determined to be unsuccessful.

[0061] In applications, obtaining the fault level of an energy storage system refers to the BMS parsing the numerical field representing the overall fault status of the energy storage system from the received EMS data frame according to a predefined communication protocol format. This value is the result of the EMS's comprehensive diagnosis of the status of external units such as PCS, TMS, and fire protection system.

[0062] In application, if the fault level of the energy storage system is lower than the preset fault level, the judgment is considered passed. This means that the BMS compares the parsed fault level value with a preset threshold, which is usually set to 3, representing the highest level of severe fault. If the actual fault level value is 0, 1, or 2, all less than 3, it means that the overall state of the energy storage system allows for high-voltage power-on, and the judgment is passed.

[0063] Specifically, the BMS processor extracts an 8-bit integer value from the decoded system fault level data packet, and then executes a comparison instruction in the program logic to compare the value with the immediate value 3. If the comparison result is true, the fault level judgment step outputs a pass signal.

[0064] The fault level of the energy storage system can be obtained by extracting specific data bytes from the CAN bus message or by reading from the Modbus RTU protocol register address. The preset fault level can use a fixed threshold of 3, or it can be set as a configurable parameter according to the system operating mode, which can be modified by maintenance personnel via a host computer.

[0065] This application incorporates the system fault status on the EMS side into the decision-making basis for high-voltage power-on, breaking the limitation of only focusing on the battery's own status and realizing the collaborative judgment of the overall safety status of the energy storage system. This means that even if the battery itself is intact, if the PCS is faulty or the fire protection system is abnormal, the high-voltage power-on process will still be prohibited, thereby building a more comprehensive and systematic safety protection system.

[0066] In one embodiment, determining whether the pre-charging has timed out during the pre-charging process includes: If the BMS fails to report a timeout fault in sending the AC high-voltage circuit power-on command, then based on formula t t =(R PC +R B )×(C PCS +C AC )×ln(U B / (U B -U PCS )) Calculate the theoretical precharge time; If the BMS reports a timeout fault in the AC high-voltage circuit power-on command transmission, then based on formula t t =(R PC +R B )×C PCS ×ln(U B / (U B -U PCS )) Calculate the theoretical precharge time; If the precharge duration exceeds the theoretical precharge duration, then a precharge timeout is determined. Among them, tt For the theoretical pre-charge duration, R PC R is the pre-charge resistance value. B C represents the real-time internal resistance of the battery. PCS For PCS capacitance value, C AC For AC capacitance, U B U represents the real-time total battery voltage. PCS This refers to the voltage at the PCS terminal.

[0067] In application, the calculation of theoretical precharge time based on different formulas means that the calculation of precharge time depends on the actual load conditions. The size of the load is mainly determined by the equivalent capacitance of the load end. If the AC high-voltage circuit power-on command does not time out, that is, the AC side also needs to be powered on, then the load capacitance is the sum of the PCS capacitance and the AC capacitance. If the AC command times out, that is, only the PCS is powered on this time, then the load capacitance is only the PCS capacitance. Other parameters in the formula, such as precharge resistance, battery internal resistance, battery voltage, etc., are all real-time or near real-time data.

[0068] In application, if the precharge time exceeds the theoretical precharge time, it is determined that the precharge timeout means that the BMS starts a high-precision timer at the moment the precharge relay is activated, and compares the current time value with the theoretical precharge time threshold calculated according to the formula in real time. If the actual precharge time has exceeded the theoretical value, but the voltage at the PCS terminal detected by the voltage sensor has not reached the predetermined percentage of the total battery voltage, such as 95%, it is determined to be a precharge timeout fault.

[0069] The theoretical precharge time can be calculated using the aforementioned empirical formula, or by interpolating from a table of voltage, current, and time relationships obtained through prior experimental measurements. To determine if the precharge has timed out, a software timer can be used to compare the time with the theoretical value, or a hardware timer circuit can be used to trigger an interrupt signal when the timer reaches a set value.

[0070] This application introduces a dynamically variable theoretical precharge time based on actual circuit parameters as the judgment standard, instead of using a fixed time threshold. This makes the judgment of precharge timeout more accurate and adaptive, and can adapt to the effects of battery voltage fluctuations, component parameter tolerances, and different power-on modes on the PCS alone or on the PCS and AC at the same time. It effectively prevents the problem of the precharge process going on indefinitely or failing undetected due to precharge circuit abnormalities such as open circuit of precharge resistor or failure of precharge relay, and improves the safety monitoring capability of the precharge stage.

[0071] In one embodiment, determining whether the high-voltage circuit is in normal condition based on the difference between the PCS terminal voltage and the real-time total battery voltage includes: Calculate the difference between the PCS terminal voltage and the real-time total voltage of the battery; If the difference does not exceed the preset voltage threshold, the high-voltage circuit is determined to be in normal condition. If the difference exceeds the preset voltage threshold, the high-voltage circuit is determined to be in an abnormal state.

[0072] In applications, calculating the difference between the PCS terminal voltage and the real-time total battery voltage refers to the total voltage U across the positive and negative terminals of the battery cluster collected by the BMS through two high-precision voltage sensors after the high-voltage main circuit is turned on. B The voltage U across the positive and negative terminals of the DC input side of the PCS PCS Typically, these two voltage values ​​are very close. The BMS processor obtains the difference ΔU between them through subtraction, meaning ΔU equals U. B minus U PCS The absolute value of.

[0073] In application, the condition that the high-voltage circuit is considered normal if the difference does not exceed the preset voltage threshold means that the BMS compares the calculated voltage difference ΔU with a very small safety threshold, usually set to 1V. If ΔU is less than or equal to 1V, it means that the voltage drop generated by the current flowing from the battery through the main circuit relay and cable to the PCS terminal is very small, the line connection is good, the relay contact resistance is normal, and the circuit status is confirmed to be normal.

[0074] Specifically, the BMS control unit periodically reads the total battery voltage value and the PCS terminal voltage value after conversion by the ADC module, performs numerical filtering, subtracts them and takes the absolute value to obtain ΔU. Then, ΔU is compared with the threshold of 1.0V stored in memory. If ΔU is less than or equal to 1.0, a normal circuit signal is generated and the precharge relay is disconnected.

[0075] The difference can be calculated by directly subtracting the sampled values ​​of the two voltage channels, or by using a differential amplifier circuit to directly output the analog signal of the difference between the two voltage channels for sampling. The preset voltage threshold can be a fixed 1V threshold, or a reference threshold can be dynamically calculated based on the rated operating current and the maximum allowable loop resistance.

[0076] This application embodiment adds a voltage difference detection step after the main positive relay is engaged, thereby achieving the final verification of the high-voltage main circuit connection quality. This inspection can effectively identify hidden faults such as the positive or negative relay issuing an engagement command but the actual contacts not closing reliably, or the bus connector being loose and causing excessive contact resistance. This avoids the system operating under load in an unsafe state with loose connections or high impedance connections in the main circuit, and prevents the fire risk that may be caused by overheating and arcing at the contact points. It is an important safety barrier for the high-voltage power-on process.

[0077] In one embodiment, the predetermined ratio is 95%.

[0078] In application, a predetermined ratio of 95% is an optimized value that has undergone engineering trade-offs. This ratio is set to strike a balance between ensuring safety and reducing surges. If the ratio is set too high, such as 98%, the voltage rise will be very slow in the later stages of the precharge process, which will unnecessarily prolong the entire power-on time and reduce system efficiency. If the ratio is set too low, such as 90%, there will still be a large voltage difference when the main positive relay is energized, which may generate a large surge current and arcing risk. 95% has been proven in practice to effectively limit the surge current within a safe range, while the precharge time is also within a reasonable range.

[0079] Specifically, during the pre-charging process, the BMS continuously monitors the PCS terminal voltage U. PCS And calculate it with the real-time total battery voltage UB, when U PCS Greater than or equal to U B When the condition is multiplied by 95%, the BMS determines that the pre-charge is successful and then issues a command to engage the positive relay.

[0080] The predetermined ratio can be 95%, but can also be adjusted to other empirical values ​​such as 92% or 97% depending on the load characteristics or the relay's surge resistance. Whether the PCS terminal voltage has reached the predetermined ratio can be determined using software comparison instructions or a hardware comparator circuit. A trigger signal is output when the voltage reaches the set ratio.

[0081] Quantifying the pre-charge completion standard into a clear voltage ratio makes the judgment of the pre-charge end point clear, consistent, and easy to implement. This avoids premature or delayed activation of the main relay due to ambiguous judgment conditions. The specific value of 95% is a good trade-off between safety and efficiency in engineering. It ensures that the remaining voltage difference when the main relay is activated is small enough to suppress the inrush current within the range that the relay contacts can safely withstand. This significantly reduces the risk of contact arcing and welding, extends the electrical life of the relay, and ensures the smoothness of high-voltage power-on operation.

[0082] like Figure 2 As shown, the method in this embodiment consists of four stages: BMS self-test, EMS high-voltage power-on signal judgment, high-voltage pre-charge, and high-voltage circuit status judgment.

[0083] like Figure 3 As shown, in the EMS high-voltage power-on signal judgment stage, three aspects are mainly judged: the integrity, authenticity, and value of the EMS high-voltage power-on signal. According to... Figure 1In an energy storage system, the battery high-voltage circuit load consists of the PCS and AC, with the PCS high-voltage circuit and AC high-voltage circuit connected in parallel. Therefore, the EMS's high-voltage power-on signal includes both the PCS high-voltage circuit power-on command and the AC high-voltage circuit power-on command. Simultaneously, the EMS is responsible for monitoring and managing the faults of components other than the battery in the energy storage system. The fault levels of these components affect the safety of high-voltage power-on. Thus, the energy storage system fault level is part of the EMS's high-voltage power-on signal. Therefore, the EMS has three high-voltage power-on signals: the PCS high-voltage circuit power-on command, the AC high-voltage circuit power-on command, and the energy storage system fault level. To protect all high-voltage relays and ensure the safety of high-voltage power-on in the energy storage system, the EMS needs to send all high-voltage power-on signals to the BMS simultaneously. Therefore, the integrity judgment of the EMS's high-voltage power-on signal depends on whether the BMS can simultaneously receive the PCS high-voltage circuit power-on command, the AC high-voltage circuit power-on command, and the energy storage system fault level. If the BMS does not simultaneously receive the PCS high-voltage circuit power-on command and the energy storage system fault level, it must continue to wait. When the BMS simultaneously receives the PCS high-voltage circuit power-on command and the energy storage system fault level, it enters the EMS high-voltage power-on signal authenticity judgment stage. If no AC high-voltage circuit power-on command is received, the BMS waits for the EMS AC high-voltage circuit power-on command. If the waiting time exceeds 3 EMS communication cycles, the BMS will no longer receive the EMS AC high-voltage circuit power-on command, and the BMS will report an AC high-voltage circuit power-on command transmission timeout fault, entering the EMS high-voltage power-on signal authenticity judgment stage. The EMS high-voltage power-on signal authenticity judgment refers to the BMS verifying the received EMS high-voltage power-on signal (signal type can be CAN, RS485, or RS232, etc.) to check the authenticity of the signal. The verification method uses CRC32. After the CRC32 verification passes, it enters the EMS high-voltage power-on signal value judgment stage. The EMS high-voltage power-on signal value judgment refers to the BMS judging the magnitude of the received energy storage system fault level value. If the energy storage system fault level value is 3, the BMS needs to continue waiting; if the energy storage system fault level value is less than 3, it enters the high-voltage pre-charging stage.

[0084] like Figure 4 As shown, during the high-voltage pre-charge stage, the BMS engages the negative terminal with the pre-charge relay for pre-charge. During pre-charge, the BMS simultaneously monitors the PCS terminal voltage and timestamp t. r If the theoretical precharge time t is exceeded t This indicates an abnormality in the pre-charge circuit. The BMS reports a pre-charge timeout fault and disconnects the negative terminal from the pre-charge relay, restarting the high-voltage pre-charge. The theoretical pre-charge time t is calculated under the condition that the BMS reports a timeout fault in sending the AC high-voltage circuit power-on command. t =(R PC +R B )×C PCS ×ln(U B / (U B-U PCS The theoretical precharge time t in the case where the BMS does not report a timeout fault in sending the AC high-voltage circuit power-on command. t =(R PC +R B )×(C PCS +C AC )×ln(U B / (U B -U PCS )), where R PC For pre-charge resistance value, R B For the real-time internal resistance of the battery, C PCS For PCS capacitance value, C AC AC capacitance, U B For the real-time total battery voltage, U PCS This refers to the PCS terminal voltage. When the PCS terminal voltage reaches more than 95% of the battery's real-time total voltage and the pre-charge time does not exceed the theoretical pre-charge time, the high-voltage circuit status judgment stage begins.

[0085] During the high-voltage circuit status assessment phase, the BMS engages the positive relay and simultaneously compares the PCS terminal voltage with the real-time total battery voltage. If the difference does not exceed 1V, the high-voltage circuit is considered normal, and the BMS disconnects the pre-charge relay, completing the high-voltage power-on of the energy storage system. If the difference exceeds 1V, the high-voltage circuit is considered abnormal, the BMS disconnects all high-voltage relays, reports a high-voltage circuit status abnormality fault, and the high-voltage power-on of the energy storage system is not completed, entering the high-voltage pre-charge phase.

[0086] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0087] This application also provides an energy storage system, including a battery cell, an energy storage converter (PCS), an energy storage management system (EMS), and a battery management system (BMS), wherein the battery management system (BMS) is used to execute the methods described in any of the above embodiments.

[0088] In application, this system involves a battery management system (BMS), a power conversion system (PCS), an energy management system (EMS), and a thermal management system (TMS).

[0089] The battery management system is a control unit responsible for collecting, monitoring, and managing battery status. The energy storage converter is a device that connects the energy storage unit to the grid to achieve bidirectional DC / AC conversion of electrical energy. The energy storage management system is responsible for monitoring, controlling, and optimizing the operation of the energy storage system; it is the "brain" of the energy storage system. The energy storage thermal management system is a heat conversion unit responsible for temperature control and regulation of the energy storage system.

[0090] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for high-voltage power-on of an energy storage system, characterized in that, The method, executed by the battery management system (BMS), includes: In response to a wake-up signal, a self-test is performed to determine the battery fault level, wherein the battery fault level is used to determine whether the battery meets the high-voltage power-on conditions. If the battery meets the high-voltage power-on conditions, then the high-voltage power-on signal received from the energy storage management system (EMS) is judged to pass the test. If the high-voltage power-on signal of the EMS passes, the negative relay and the pre-charge relay are activated to start the pre-charge process, and the pre-charge process is checked to determine whether the pre-charge has timed out. If the pre-charging process does not time out and the PCS terminal voltage reaches a predetermined proportion of the battery's real-time total voltage, then the positive relay is activated, and the status of the high-voltage circuit is determined based on the difference between the PCS terminal voltage and the battery's real-time total voltage. If the high-voltage circuit is in normal condition, the pre-charge relay will be disconnected to complete the high-voltage power-on.

2. The high-voltage power-on method for an energy storage system as described in claim 1, characterized in that, The determination of whether the battery meets the high-voltage power-on conditions includes: When the battery fault level is a fault level that allows the battery to be powered on at high voltage, it is determined that the battery meets the conditions for high voltage power-on. When the battery fault level is a fault level that does not allow the battery to be powered on at high voltage, it is determined that the battery meets the condition of not being powered on at high voltage. The battery fault levels include at least fault levels that allow the battery to be powered at high voltage and fault levels that do not allow the battery to be powered at high voltage.

3. The high-voltage power-on method for an energy storage system as described in claim 1, characterized in that, The process of determining whether the received high-voltage power-on signal from the energy storage management system (EMS) passes the test includes: Based on the PCS high-voltage circuit power-on command, the energy storage system fault level, and the AC high-voltage circuit power-on command, the EMS high-voltage power-on signal is sequentially assessed for integrity, authenticity, and fault level.

4. The high-voltage power-on method for an energy storage system as described in claim 3, characterized in that, The integrity determination includes: If the PCS high-voltage circuit power-on command and the energy storage system fault level are received simultaneously, and the AC high-voltage circuit power-on command is received within a predetermined time, then the integrity judgment is determined to be successful. If the PCS high-voltage circuit power-on command and the energy storage system fault level are not received simultaneously, or if the AC high-voltage circuit power-on command is not received within a predetermined time period, then the integrity judgment is determined to be unsuccessful.

5. The high-voltage power-on method for an energy storage system as described in claim 3, characterized in that, The authenticity verification includes: Perform CRC verification on the received high-voltage power-on signal of the EMS; If the CRC check passes, then the authenticity determination is considered successful.

6. The high-voltage power-on method for an energy storage system as described in claim 3, characterized in that, The fault level determination includes: Obtain the fault level of the energy storage system; If the fault level of the energy storage system is lower than the preset fault level, then the fault level determination is passed; If the fault level of the energy storage system is not lower than the preset fault level, then the fault level judgment is determined to be unsuccessful.

7. The high-voltage power-on method for an energy storage system as described in claim 1, characterized in that, The step of determining whether the pre-charging has timed out during the pre-charging process includes: If the BMS fails to report a timeout fault in sending the AC high-voltage circuit power-on command, then based on formula t t =(R PC +R B )×(C PCS +C AC )×ln(U B / (U B -U PCS )) Calculate the theoretical precharge time; If the BMS reports a timeout fault in the AC high-voltage circuit power-on command transmission, then based on formula t t =(R PC +R B )×C PCS ×ln(U B / (U B -U PCS )) Calculate the theoretical precharge time; If the precharge duration exceeds the theoretical precharge duration, then a precharge timeout is determined. Among them, t t For the theoretical pre-charge duration, R PC R is the pre-charge resistance value. B C represents the real-time internal resistance of the battery. PCS For PCS capacitance value, C AC For AC capacitance, U B U represents the real-time total battery voltage. PCS This refers to the voltage at the PCS terminal.

8. The high-voltage power-on method for an energy storage system as described in claim 1, characterized in that, The method of determining whether the high-voltage circuit is in normal condition based on the difference between the PCS terminal voltage and the real-time total battery voltage includes: Calculate the difference between the PCS terminal voltage and the real-time total voltage of the battery; If the difference does not exceed the preset voltage threshold, the high-voltage circuit is determined to be in normal condition. If the difference exceeds the preset voltage threshold, the high-voltage circuit is determined to be in an abnormal state.

9. The high-voltage power-on method for an energy storage system as described in claim 1, characterized in that, The predetermined ratio is 95%.

10. An energy storage system, characterized in that, It includes a battery cell, an energy storage converter (PCS), an energy storage management system (EMS), and a battery management system (BMS), wherein the battery management system (BMS) is used to perform the method as described in any one of claims 1 to 9.

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