Battery management system, electric vehicle, method for controlling battery power-on and power-off

Abstract

The embodiment of the application provides a battery management system, an electric vehicle and a battery power-on and power-off control method, relates to the technical field of battery management, and the battery management system is configured to: receive and respond to a power-on instruction, instruct a pre-charging relay to be closed, and repeatedly execute the following steps: collecting the terminal voltage of the battery and the terminal voltage of a load according to a first preset period, and calculating the voltage difference between the terminal voltage of the battery and the terminal voltage of the load; until the first number of voltage differences are all less than a first preset threshold value within a pre-charging time, instructing a main positive relay to be closed; obtaining a feedback signal of an auxiliary contact of the main positive relay; if the feedback signal represents that the auxiliary contact is in a conduction state, instructing a main negative relay to be closed; and instructing the pre-charging relay to be disconnected after a first preset time interval, so as to complete a high-voltage power-on operation. Through the embodiment of the application, the problem that a surge current much higher than a rated working current is generated at the moment when the main relay is closed in the related art, and the problem of contact ablation are solved.

Description

Technical Field

[0001] This application relates to the field of battery management technology, and in particular to battery management systems, electric vehicles, and control methods for powering on and off batteries. Background Technology

[0002] The Battery Disconnect Unit (BDU) of a new energy vehicle is typically located between the battery and the vehicle's high-voltage load, and is used to control the connection and disconnection of the high-voltage circuit. This BDU usually includes a high-voltage main relay for controlling the battery's main circuit and a pre-charge relay for pre-charging the high-voltage bus. The timing of the on / off operation of the high-voltage relay directly affects the electrical safety and system reliability between the battery and the load.

[0003] In existing technologies, the power-on control strategy for high-voltage relays generally employs synchronous closing of the main relay and the pre-charge relay, or only a very short delay before closing the main relay. However, because the load-side equipment typically has a large capacitance, the load-side voltage is close to zero in the initial state, and the voltage difference between the load and the battery terminals is almost equal to the total battery voltage. In this situation, a surge current far exceeding the rated operating current will be generated at the moment the main relay closes, leading to contact erosion, adhesion, or even welding.

[0004] For at least one of the above-mentioned technical problems, the relevant technologies have not yet proposed an effective solution. Summary of the Invention

[0005] This application provides a battery management system, an electric vehicle, and a method for controlling the power-on and power-off of a battery to solve one or more of the aforementioned technical problems.

[0006] As one aspect of this application embodiment, this application embodiment provides a battery management system, which is communicatively connected to a battery power distribution unit. The battery power distribution unit is connected in series between the battery and the load. The output terminal of the battery power distribution unit is connected to a current sensor. The battery power distribution unit includes a high-voltage main circuit and a pre-charge circuit. The high-voltage main circuit includes a main positive relay and a main negative relay. The pre-charge circuit includes a pre-charge relay. The battery management system is configured to: receive and respond to a power-on command, instruct the pre-charge relay to close, and repeatedly execute the following steps: collect the terminal voltage of the battery and the terminal voltage of the load according to a first preset period, and calculate the voltage difference between the terminal voltage of the battery and the terminal voltage of the load; until, within the pre-charge time, a first number of consecutive voltage differences are not greater than a first preset threshold, instruct the main positive relay to close; obtain the feedback signal of the auxiliary contact of the main positive relay; if the feedback signal indicates that the auxiliary contact is in a conducting state, instruct the main negative relay to close; after a first preset time interval, instruct the pre-charge relay to open to complete the high-voltage power-on operation.

[0007] As another aspect of the embodiments of this application, this application provides an electric vehicle, including: a controller and a battery device, the battery device including one or more battery packs, the battery pack including the above-mentioned battery management system, battery group, and battery power distribution unit; after receiving an instruction sent by the controller, the battery management system controls the battery power distribution unit according to the instruction type.

[0008] As another aspect of the embodiments of this application, this application provides a battery power-on / off control method, applied to the above-mentioned battery management system, including: receiving and responding to a power-on command, instructing the pre-charge relay to close, and repeatedly executing the following steps: collecting the terminal voltage of the battery and the terminal voltage of the load according to a first preset period, and calculating the voltage difference between the terminal voltage of the battery and the terminal voltage of the load; until within the pre-charge time, a first number of consecutive voltage differences are not greater than a first preset threshold, instructing the main positive relay to close; acquiring a feedback signal of the auxiliary contact of the main positive relay; if the feedback signal indicates that the auxiliary contact is in a conducting state, instructing the main negative relay to close; after an interval of a first preset time, instructing the pre-charge relay to open, so as to complete the high-voltage power-on operation; receiving and responding to a power-off command, and repeatedly executing the following steps: collecting the second current value of the current sensor according to a third preset period; until within a third preset time, a third number of consecutive second current values ​​are not greater than a third preset threshold, instructing the main negative relay to open; after an interval of a second preset time, instructing the main positive relay to open, so as to complete the high-voltage power-off operation.

[0009] In the technical solution described in this application embodiment, after the pre-charge relay closes, the voltage difference between the battery terminal voltage and the load terminal voltage is monitored. The main positive relay is only controlled to close when this voltage difference is lower than a preset safety threshold, instead of controlling the main positive relay to close synchronously with the pre-charge relay or directly after a fixed delay. This solves the technical problem in related technologies where the main relay closing instant generates a surge current far exceeding the rated operating current, leading to contact erosion, adhesion, or even welding. Furthermore, compared to a simple fixed delay, the technical solution in this application embodiment uses voltage difference monitoring for closed-loop determination, which can adapt to differences in load capacitance and aging of the pre-charge circuit.

[0010] In addition, a dynamic voltage difference monitoring scheme is proposed, which continuously verifies the voltage difference over multiple consecutive cycles and closes the main positive relay only when all voltage differences are below a preset safety threshold. Compared with the technical solution that uses instantaneous voltage difference to determine the completion of pre-charging, the above scheme in this application improves the reliability of pre-charging.

[0011] The above-mentioned main relay hierarchical closing scheme ensures that both the positive and negative terminals of the high-voltage main circuit supply power to the load through low-impedance main contacts, thereby improving the stability of the high-voltage load power supply of the entire vehicle.

[0012] In addition, by performing a secondary confirmation of the closing state of the main relay, it can be ensured that both the positive and negative terminals of the high-voltage main circuit supply power to the load through the low-impedance main contacts, thereby improving the stability of the high-voltage load power supply of the entire vehicle.

[0013] In addition, after a first preset time interval, the pre-charge relay is disconnected, so that the current is fully carried by the main circuit to complete the high-voltage power-on, which achieves the technical effect of improving the safety of high-voltage power-on and reducing the voltage drop of the circuit.

[0014] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application, it can be implemented according to the contents of the specification. In order to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0015] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments according to this application and should not be construed as limiting the scope of this application.

[0016] Figure 1 A schematic diagram of a high-voltage power-on / off control method in the related technology provided in the embodiments of this application;

[0017] Figure 2A schematic diagram of the connection frame for BMS, BDU, battery, vehicle high-voltage load, and VCU provided in the embodiments of this application;

[0018] Figure 3 A schematic diagram of a BMS power-on control process provided in an embodiment of this application is shown;

[0019] Figure 4 A schematic diagram of a BMS control power-on / off process provided in an embodiment of this application is shown;

[0020] Figure 5 This application provides a schematic diagram of the structure of an electric vehicle according to an embodiment of the present application;

[0021] Figure 6 This illustration shows a schematic diagram of the structure of a battery pack provided in an embodiment of this application;

[0022] Figure 7 A flowchart of a battery power-on / off control method provided in an embodiment of this application is shown;

[0023] Figure 8 This paper shows a structural block diagram of a battery power-on / off control device provided in an embodiment of this application;

[0024] Figure 9 A structural block diagram of the controller used to implement the embodiments of this application is shown. Detailed Implementation

[0025] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the concept or scope of this application. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0026] To facilitate understanding of the technical solutions of the embodiments of this application, the relevant technologies of the embodiments of this application are described below. The following relevant technologies are optional solutions and can be combined with the technical solutions of the embodiments of this application in any way, and all of them fall within the protection scope of the embodiments of this application.

[0027] The technical solution of this application and how it solves the aforementioned technical problems are described in detail below with specific embodiments. The listed specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0028] High-voltage power-on / off control methods in related technologies, such as Figure 1 As shown, it includes the following steps:

[0029] S101, System standby;

[0030] S102, determine whether a power-on command has been received; if so, proceed to step S103.

[0031] S103, close the main negative relay;

[0032] S104, close the pre-charge relay and simultaneously start the fixed delay T1;

[0033] S105, wait for the fixed delay T1 to end;

[0034] S106, Close the main positive relay;

[0035] S107, disconnect the pre-charge relay;

[0036] S108, high voltage power-on complete;

[0037] S109, determine whether a power-down command has been received;

[0038] S110 directly disconnects the main positive relay. It should be noted that a large current still flows through the circuit during this process.

[0039] S111, disconnect the main negative relay;

[0040] S112, high voltage energization complete.

[0041] The aforementioned high-voltage power-on control strategy generates a surge current far exceeding the rated operating current at the moment the main positive relay closes, leading to contact erosion, adhesion, or even welding. The aforementioned high-voltage power-off control strategy directly disconnects the main positive relay, but residual charge remains in the capacitors in the circuit. The voltage and current superposition at the moment of disconnection easily generates high-voltage arcing, causing contact oxidation, decreased insulation performance, and even fire hazards.

[0042] In view of this, embodiments of this application provide a battery management system to solve all or part of the above-mentioned technical problems. Figure 2This is a schematic diagram illustrating the connection framework of the Battery Management System (BMS), Battery Unit (BDU), battery, vehicle high-voltage load, and Vehicle Control Unit (VCU) provided in this embodiment. The battery, acting as a high-voltage power supply, is electrically connected to the high-voltage input terminal of the BDU. The BDU, arranged in series between the battery and the vehicle high-voltage load, is the core execution component of the high-voltage circuit. Internally, it integrates a high-voltage main circuit and a pre-charge circuit connected in parallel. The high-voltage main circuit consists of a main positive relay, a main negative relay, and a high-voltage bus. The pre-charge circuit consists of a pre-charge relay and a pre-charge resistor connected in series. Additionally, a current sensor is connected to the output terminal of the BDU to collect the main circuit current. The BMS establishes electrical and signal acquisition connections with the battery and each relay within the BDU, enabling real-time acquisition of battery operating parameters and circuit voltage, and independent control of the on / off sequence of each relay. Simultaneously, the BMS establishes a bidirectional communication link with the VCU, receiving power-on control commands from the VCU in real time and synchronously feeding back the high-voltage system operating status, fault information, and power-on conditions to the VCU. The vehicle's high-voltage load is connected to the high-voltage power supply circuit through the BDU high-voltage output terminal to receive high-voltage electrical energy output from the power battery.

[0043] The embodiments of this application optimize the power-on / off control strategy of the BMS described above, which will be explained in detail below.

[0044] like Figure 3 As shown, the BMS can be configured to: receive and respond to a power-on command, instruct the pre-charge relay to close, and repeatedly execute the following steps: collect the terminal voltage of the battery and the terminal voltage of the load according to a first preset period, and calculate the voltage difference between the terminal voltage of the battery and the terminal voltage of the load; until a first number of consecutive voltage differences are not greater than a first preset threshold within the pre-charge time, instruct the main positive relay to close; acquire the feedback signal of the auxiliary contact of the main positive relay; if the feedback signal indicates that the auxiliary contact is in a conducting state, instruct the main negative relay to close; after a first preset time interval, instruct the pre-charge relay to open to complete the high-voltage power-on operation.

[0045] Optionally, in this embodiment, the BMS may perform operating condition initialization and safety self-test before receiving the power-on command. If the self-test passes, it enters standby mode and waits for the power-on command. For example, during the self-test, the auxiliary contact status of each relay (including the main positive relay, the main negative relay, and the pre-charge relay) is read, or the current physical state of each relay is judged based on the circuit voltage acquisition results combined with preset logic to confirm that no relay is in an unexpected closed or stuck state. If it is detected that the circuit of the main positive relay or the main negative relay is connected without issuing a closing command, it is determined to be a relay stuck fault. Under this fault determination result, the power-on process is prohibited, and the fault information is reported to the VCU to trigger corresponding safety protection measures and fault prompts.

[0046] Before instructing the pre-charge relay to close, the main negative relay can be instructed to close first, thus establishing a detection circuit for collecting the battery terminal voltage and the load terminal voltage. That is, reliably connecting the battery negative terminal to the vehicle's high-voltage load negative terminal in advance establishes a stable and unified reference ground potential for the vehicle's high-voltage circuit. This ensures that the sampling benchmark for the battery terminal voltage and the load terminal voltage is consistent during the pre-charge phase, avoiding voltage sampling deviations, inaccurate voltage difference judgments, and pre-charge misjudgments caused by the high-voltage load negative terminal being unconnected or experiencing potential fluctuations. This ensures accurate and reliable subsequent voltage difference monitoring results, providing an accurate data foundation for precise control of pre-charge termination and main circuit closure timing based on voltage difference thresholds, thereby improving the safety and accuracy of the vehicle's high-voltage power-on control from the ground up.

[0047] It is understandable that the aforementioned first preset period can be determined based on parameters such as the dynamic characteristics of battery voltage changes and the detection time limit for vehicle functional safety faults. For example, the aforementioned first preset period T1 can be 10ms.

[0048] In this embodiment, the method for acquiring the battery terminal voltage and the load terminal voltage, and calculating the voltage difference between them, can be as follows: Voltage acquisition channels are set up between the high-voltage positive and high-voltage negative terminals of the battery to acquire the battery terminal voltage V_bat, and voltage acquisition channels are set up between the positive and negative terminals of the load side of the high-voltage bus to acquire the load terminal voltage V_load. After receiving the sampled values ​​of the battery terminal voltage V_bat and the load terminal voltage V_load, the difference between them is calculated and used as the real-time voltage difference ΔV = |V_bat - V_load|.

[0049] It is understood that the aforementioned pre-charge time can be determined based on the load-side bus capacitor capacity and the current-limiting parameters of the pre-charge circuit (such as the resistance value of the pre-charge resistor, the relay contact resistance, etc.), enabling the high-voltage bus voltage to approach the battery terminal voltage under most vehicle models and electrical configurations, thereby meeting the safety closing conditions of the subsequent high-voltage main circuit. Optionally, the aforementioned pre-charge time can be set to 2000ms. Furthermore, in this embodiment, the product of the aforementioned first quantity and the first preset period is less than the pre-charge time. For example, this product can be 300ms.

[0050] Additionally, it can be understood that the aforementioned first preset threshold is a safety limit value for determining whether pre-charging is complete. When the voltage difference between the battery terminal voltage and the load terminal voltage is less than or equal to this threshold, it is considered that the bus terminal capacitor is basically fully charged, and there is no risk of surge impact when closing the main circuit relay. Optionally, the aforementioned first preset threshold ΔV_safe can be set to 5V.

[0051] It should be noted that the pre-charging time and the first preset threshold can be adjusted according to the load characteristics of different vehicles, bus voltage levels (e.g., 300V, 400V, 800V, etc.), and the status of the pre-charging circuit. For example, under light load conditions, the pre-charging time can be shortened to 500ms to 1000ms, while under heavy load conditions or when the pre-charging circuit is aging, it can be extended to 3000ms to 5000ms. The first preset threshold can also be adjusted to the range of 3V to 10V according to the contactor's electrical life requirements and system safety strategies.

[0052] The aforementioned first preset duration is used to avoid arcing or mechanical vibration of the pre-charge relay contacts caused by current fluctuations at the moment the main circuit relay closes, ensuring that the main circuit power supply is completely stable before disconnecting the pre-charge circuit. This first preset duration can be set from 50 milliseconds to 100 milliseconds. For example, when the sampling period is 10 milliseconds, a duration of 50 milliseconds (approximately 5 sampling periods) can be selected as the fast disconnection mode. In cases of large load fluctuations or long relay mechanical engagement times, it can be extended to 100 milliseconds to increase the safety margin.

[0053] Of course, the range of the first preset duration can be adjusted according to the high voltage platform (such as 300V, 400V, 800V), main relay engagement characteristics, and load type of different vehicles. For example, for high-speed response solid-state switch systems, the duration can be shortened to 10 to 20 milliseconds, while for mechanical relay systems with large initial load fluctuations, it can be increased to 200 milliseconds to ensure stability.

[0054] The BMS provided in this application embodiment monitors the voltage difference between the battery terminal voltage and the load terminal voltage after the pre-charge relay closes. It controls the main positive relay to close only when this voltage difference is lower than a preset safety threshold, instead of controlling the main positive relay to close synchronously with the pre-charge relay or after a fixed delay. This solves the technical problem in related technologies where the main relay closing instant generates a surge current far exceeding the rated operating current, leading to contact erosion, adhesion, or even welding. Moreover, compared to a simple fixed delay, the technical solution in this application embodiment uses voltage difference monitoring for closed-loop determination, which can adapt to load capacitance differences and pre-charge circuit aging. Furthermore, a dynamic voltage difference monitoring scheme is proposed, which continuously verifies the voltage difference over multiple cycles, closing the main positive relay only when all voltage differences are lower than the preset safety threshold. Compared to the technical solution that uses instantaneous voltage difference to determine pre-charge completion, the above scheme in this application embodiment improves pre-charge reliability. Through the above-mentioned graded closure scheme of the main relay, it can be ensured that both the positive and negative terminals of the high-voltage main circuit supply power to the load through low-impedance main contacts, improving the stability of the high-voltage load power supply to the entire vehicle. Furthermore, by performing a secondary confirmation of the main relay's closed state, it can be ensured that both the positive and negative terminals of the high-voltage main circuit supply power to the load through the low-impedance main contacts, thus improving the stability of the vehicle's high-voltage load power supply. In addition, after a first preset interval, the pre-charge relay is then controlled to open, allowing the current to be fully carried by the main circuit to complete the high-voltage energization, achieving the technical effects of improving high-voltage energization safety and reducing circuit voltage drop.

[0055] This application also proposes a safety control strategy for precharge timeout. In an optional implementation, the BMS is further configured to: if the voltage difference obtained during the precharge time is greater than a first preset threshold, instruct the precharge relay and the main negative relay to disconnect and report a first fault.

[0056] In other words, if the timeout does not satisfy ΔV≤ΔV_safe, it is determined as a precharge failure, the control disconnects the precharge relay and the main negative relay, and reports the precharge timeout fault to the VCU.

[0057] The above-mentioned optional implementation methods can promptly disconnect abnormal pre-charge circuits, preventing damage to high-voltage components from insufficient pre-charge of the bus capacitor and subsequent overcurrent during closing. Simultaneously, it terminates the long-term energization and overheating of the pre-charge resistor, preventing component burnout. Furthermore, dedicated fault reporting accurately identifies pre-charge circuit anomalies, facilitating vehicle fault diagnosis and repair.

[0058] This application also proposes a safety control strategy for pre-charge overcurrent. In an optional implementation, the BMS is further configured to: re-execute the following steps: collect the first current value of the current sensor according to the second preset period; until the first current value is greater than the second preset threshold for a second consecutive number of times during the pre-charge time, then instruct the pre-charge relay and the main negative relay to disconnect and report the second fault.

[0059] Optionally, in this embodiment, the second preset period can be determined based on parameters such as the dynamic characteristics of battery voltage changes and the detection time limit for vehicle functional safety faults. For example, the second preset period T2 can be 1 to 20 ms. To filter out false judgments of instantaneous single-current exceedances caused by sampling noise, this embodiment proposes a second quantity, which can be, for example, 1 to 5. The second preset threshold is the maximum allowable pre-charge current, for example, 15A.

[0060] In other words, when the main circuit current I_main is detected to exceed the preset maximum allowable current, it is determined that an overcurrent abnormality has occurred during the pre-charging process, which is highly likely to pose safety hazards such as high-voltage load short circuit, circuit insulation abnormality, and device failure. At this time, the BMS immediately triggers the emergency protection logic, synchronously controlling the pre-charging relay and the previously closed main negative relay to quickly disconnect, completely cutting off the high-voltage pre-charging circuit and the high-voltage negative reference circuit, quickly isolating the high-voltage fault path, and preventing safety risks such as overheating and burnout of the pre-charging resistor, relay contact erosion, power battery overload damage, and high-voltage fire caused by continuous overcurrent impact.

[0061] For example, taking an electric vehicle as an example, the rated total voltage of the battery is 400V. Based on the pre-charging resistance value, high-voltage load capacitance value, and system safety conditions, the maximum allowable safe current during the pre-charging process is pre-calibrated to be 15A. Under normal pre-charging conditions, the pre-charging current in the circuit remains stable within the range of 3A to 10A, not exceeding the preset threshold. The BMS determines that the pre-charging condition is normal and continues to execute real-time differential pressure monitoring and normal pre-charging sequence. If an abnormality occurs in the high-voltage load of the vehicle, such as a slight short circuit at the high-voltage end of the high-voltage air conditioning compressor or on-board charger (OBC), insulation damage to the high-voltage wiring harness, or breakdown of the load capacitive module, a sudden current surge will occur at the moment the pre-charging circuit is turned on. When the BMS collects the instantaneous current of the high-voltage circuit in real time and it exceeds the preset safety threshold of 15A, it immediately determines that there is a pre-charging overcurrent fault. At this point, the BMS does not need to wait for the pre-charge voltage equalization to complete; it immediately executes emergency protection actions, simultaneously disconnecting the closed pre-charge relay and main negative relay, completely cutting off the high-voltage pre-charge power supply path and negative reference circuit, quickly isolating the high-voltage fault area, and preventing problems such as high-temperature burnout of the pre-charge resistor, arc erosion and adhesion of relay contacts, and overheating of the power battery caused by continuous high-current impact. Simultaneously, the BMS reports a pre-charge overcurrent fault to the vehicle's VCU, and the vehicle simultaneously locks the high-voltage power-on function, displays a high-voltage system fault warning on the instrument panel, prohibits the vehicle from being powered on and driven, and reminds maintenance personnel to check for potential faults such as high-voltage short circuits and component damage, completely avoiding high-voltage safety accidents.

[0062] In an optional implementation, the BMS is further configured to: for any target relay among the main positive relay, the main negative relay, and the precharge relay, before instructing the target relay to perform a closing operation, obtain the type of the currently closed relay; based on the type of the currently closed relay and the type of the target relay, search for the verification result of the target relay in a two-dimensional verification matrix, wherein the column dimension of the two-dimensional verification matrix represents the types of relays in a closed state, the row dimension of the two-dimensional verification matrix represents the types of relays to be closed, and each cell in the two-dimensional verification matrix is ​​configured with an authorization identifier, which includes an authorized closing identifier and a prohibited closing identifier; if the verification result is authorized closing, then instruct the target relay to close.

[0063] The two-dimensional parity-check matrix is ​​shown in Table 1 below:

[0064] Table 1

[0065]

[0066] For example, assuming the target relay is a main positive relay, and the BMS detects that the main positive relay is closed, then by looking up the two-dimensional check matrix, it is determined that closing the target relay is prohibited. Conversely, assuming the target relay is a main negative relay, and the BMS detects that the main positive relay is closed, then by looking up the two-dimensional check matrix, it is determined that closing the target relay is permitted.

[0067] The above optional implementation methods define the logical constraints between the states of each relay (such as the main positive relay and the pre-charge relay cannot be closed at the same time), which prevents any combination that may lead to short circuit or unexpected high voltage output from the control logic level, thus meeting the functional safety design requirements.

[0068] Optionally, in any embodiment of this application, if a signal inconsistent with the operation is detected during any relay operation (e.g., V_load is not dropped when the main circuit is disconnected), it is immediately determined that the relay is stuck or the control is in failure, and emergency fault protection is performed (e.g., locking all relay drive outputs, forcibly disconnecting all or retaining the precharge circuit to attempt to discharge), and the highest level fault is reported.

[0069] After instructing the precharge relay to disconnect to complete the high-voltage power-on operation, this application embodiment also provides a BMS power-off control strategy. Optionally, the BMS can be configured to: receive and respond to the power-off command, and repeatedly execute the following steps: collect the second current value of the current sensor according to a third preset period; until within a third preset time period, a third consecutive number of the second current values ​​are not greater than a third preset threshold, then instruct the main negative relay to disconnect; after an interval of a second preset time period, instruct the main positive relay to disconnect to complete the high-voltage power-off operation.

[0070] Optionally, in this embodiment, after receiving a power-down command, the BMS can send a control message to the VCU via the Controller Area Network (CAN) bus to instruct the VCU to stop the power output of the vehicle's high-voltage load. Specifically, the control message can be used to trigger the VCU to execute a power shutdown command for the load, including but not limited to reducing the drive motor torque to zero and stopping the on-board DC / DC converter, thereby ensuring the safety and stability of the high-voltage system during the power-down process.

[0071] Optionally, in this embodiment, the aforementioned third preset period can be determined based on parameters such as the dynamic change characteristics of battery voltage and the detection time limit for vehicle functional safety faults. For example, the aforementioned third preset period T3 can be 1 to 20 ms. To filter out false judgments of instantaneous single-current exceedances caused by sampling noise, this embodiment proposes a third quantity, which can be, for example, 1 to 5. The aforementioned third preset duration is a preset maximum waiting time, for example, 500 ms.

[0072] In addition, the aforementioned third preset threshold is used to determine whether the current in the high-voltage main circuit is within a safe range close to zero. For example, the third preset threshold is 1A. Of course, the setting of the third preset threshold can also be adjusted according to the system's measurement accuracy, the arc resistance of the relay contacts, and the rated current of the high-voltage system in different vehicle models. For example, for systems with a smaller rated current, the third preset threshold can be set to 0.5A; for systems with a larger rated current, the threshold can be increased to 2A to ensure the safety of contact operation.

[0073] It is understood that the aforementioned second preset duration is used to wait for residual charge in the circuit to be released through the load path such as the pre-charge resistor. Optionally, the aforementioned second preset duration T_off_delay can be 200ms.

[0074] By implementing the above optional methods, the circuit current is cleared to zero as a prerequisite for power-down disconnection, and the order of disconnecting the main negative relay first and then disconnecting the main positive relay after a delay is controlled to ensure that the circuit energy has been discharged to a safe level during disconnection, thus eliminating electric arc from the source. This solves the technical problem in related technologies where directly disconnecting the main positive relay during power-down can cause high-voltage arcing due to the current in the circuit.

[0075] This application also proposes a safety control strategy for non-zero timeout of the downcurrent. In an optional implementation, the BMS is further configured to: if the second current value is greater than the third preset threshold within the third preset time period, then instruct the main positive relay and the main negative relay to disconnect and report a third fault.

[0076] In other words, if the current is still not zero after the maximum waiting time (e.g., 500ms), then forced protection disconnection will be performed.

[0077] For example, suppose that in the high-voltage system of an electric vehicle, the battery rated voltage is 600V and the rated operating current of the high-voltage main circuit is 200A. The BMS has a built-in zero-current detection mechanism with a zero-current threshold set to 1A and a preset time set to 500ms. When entering power-down mode, the BMS receives a power-down command from the VCU and begins to monitor the high-voltage main circuit current value in real time. Ideally, during power-down, the high-voltage main circuit current should rapidly decay to near zero (≤1A) to ensure safe relay disconnection. However, if the high-voltage main circuit current remains at approximately 5A within the preset time of 500ms and fails to drop below the zero-current threshold, the BMS determines that a non-zero power-down current timeout fault has occurred. It immediately controls the main positive and main negative relays to disconnect, isolating both the positive and negative terminals of the high-voltage bus from the battery terminal. The BMS then reports the third fault information of the non-zero power-down current timeout fault to the VCU via a CAN message. The VCU then triggers the fault protection mode: stopping the drive motor, recording the fault log, illuminating the instrument fault warning light, and prompting the driver to check the motor controller, etc.

[0078] Through the above safety control strategies, the high-voltage circuit can be cut off in time during the power-off process, preventing contact arcing and erosion caused by power-off operation when there is continuous current in the main circuit, reducing the safety risks of the high-voltage system. At the same time, the fault reporting mechanism triggers vehicle safety protection or maintenance prompts, thereby improving the reliability and maintainability of the high-voltage system.

[0079] This application also proposes a power-down voltage confirmation strategy. In an optional implementation, the BMS is further configured to: monitor the rate at which the terminal voltage of the load drops to a fourth preset threshold; if the rate is less than a fifth preset threshold, instruct the pre-charge relay to close; and instruct the pre-charge relay to open after a fourth preset time interval.

[0080] Optionally, in this embodiment, the fourth preset threshold can be a preset safety voltage, such as 36V.

[0081] In other words, when the rate is less than a preset rate threshold, the pre-charge relay can be briefly closed to apply current-limited supplementary power from the battery to the high-voltage bus terminal through the pre-charge circuit, thereby accelerating the discharge process of the load terminal capacitor and allowing the load terminal voltage to drop to the safe voltage range as quickly as possible. The closing time of the aforementioned pre-charge relay is a short-term closing, typically not exceeding several hundred milliseconds, to avoid prolonged power supply causing the high-voltage circuit to be re-established or the load to restart unexpectedly.

[0082] For example, suppose that after disconnecting the main positive relay, it checks whether V_load drops to a safe voltage (e.g., ≤36V) within 1 second. If the drop is too slow, the pre-charge relay can be briefly closed for active discharge, eventually entering standby or hibernation mode.

[0083] By employing the aforementioned power-down voltage confirmation strategy, the discharge process can be proactively intervened when the voltage drop rate at the load end is too slow. This reduces the risk of the high-voltage bus end retaining a high potential for an extended period, lowers the risk of electric shock and maintenance risks, and ensures that the high-voltage system is in a safe, de-energized state after power-down.

[0084] The following examples illustrate the high-voltage power-on and high-voltage power-off control methods of this application.

[0085] like Figure 4 As shown, it includes:

[0086] Step S401: System self-test and initialization. For example, checking the initial state of the relays and whether there are any faults;

[0087] Step S402: Standby, waiting for instructions;

[0088] Step S403: Determine the instruction type. If the instruction type is a power-on instruction, execute step S404. If the instruction type is a power-off instruction, execute step S412.

[0089] Step S404: Close the main negative relay to establish a reference ground;

[0090] Step S405: Close the pre-charge relay to start pre-charge and begin timing;

[0091] Step S406: Dynamically monitor and calculate the pressure difference ΔV in real time. If ΔV ≤ 5V and remains stable for 300ms, proceed to step S407. If the precharge timeout or precharge overcurrent occurs, proceed to step S410.

[0092] Step S407: Close the main positive relay;

[0093] Step S408: Close the main negative relay;

[0094] Step S409: After a delay, the pre-charge relay is disconnected, and the high-voltage power-on is completed;

[0095] Step S410: Pre-charging is determined to have failed;

[0096] Step S411: Execute fault protection, disconnect all relays, and report the fault;

[0097] Step S412: Instruct the VCU to stop the load and wait for the power to return to zero;

[0098] Step S413: Monitor whether the main circuit current I returns to zero. If yes, proceed to step S414; otherwise, proceed to step S411.

[0099] Step S414: First, disconnect the main negative relay;

[0100] Step S415, delay for 200ms, release residual charge;

[0101] Step S416: Disconnect the main positive relay;

[0102] Step S417: Check if the voltage at the load end is safe. If yes, the high voltage power-off is completed. If no, proceed to step S418.

[0103] Step S418: Briefly close the pre-charge relay to perform active discharge.

[0104] The above-described solutions in this application completely eliminate electrical damage in actual testing and application. Specifically, through graded timing and dynamic voltage difference judgment, the power-on inrush current is reduced from hundreds of amperes in traditional solutions to near zero; by disconnecting after the current returns to zero, the arc energy after power-off is reduced by more than 90%, significantly reducing the risk of relay contact erosion and adhesion, and is expected to extend the electrical life of the relay by 30% to 50%. Furthermore, the above-described solutions in this application improve system reliability. Specifically, the adaptive pre-charge mechanism overcomes the pre-charge failure problem caused by load changes and component aging, increasing the overall high-voltage power-on success rate to over 99.9%, and the smooth switching process avoids instantaneous overload stress on the battery and load-side capacitors. The above-described solutions in this application also enhance high-voltage safety. Specifically, the improved interlocking logic and fault avoidance mechanism effectively prevent relay malfunctions caused by software malfunction or hardware failure, meeting the requirements of the Automotive Safety Integrity Level (ASIL). Active residual voltage monitoring and handling avoid the risk of electric shock during maintenance. Furthermore, it achieves high compatibility and low cost. Specifically, based on software logic implementation, it does not require changes to the existing BDU hardware topology or relay selection, and can be deployed directly by updating the BDU controller firmware. The modification cost for existing and in-production models is extremely low, and it has strong compatibility.

[0105] This application also provides an electric vehicle, such as... Figure 5 As shown, the electric vehicle 100 includes a controller 300 and a battery device 200. The battery device 200 includes one or more battery packs, which include the aforementioned battery management system, battery pack, and battery power distribution unit. After receiving an instruction from the controller, the battery management system controls the battery power distribution unit according to the instruction type.

[0106] The battery device 200 can serve as an operating power source for electrical devices, or as a driving power source for electrical devices, replacing or partially replacing fuel or natural gas to provide driving power for vehicles. Electrical devices include: energy storage devices, electric ships, aircraft, laptops, power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace, and many other technological fields. Figure 5 As shown, the vehicle can be a new energy vehicle, encompassing various types such as pure electric vehicles, hybrid electric vehicles, and range-extended electric vehicles. The battery device 200 can be located at the bottom, front, or rear of the vehicle 100, providing power support to the vehicle, for example, acting as the vehicle's operating power source. Furthermore, the vehicle 100 typically includes a controller 300, which manages the discharge process of the battery device 200 to cover various power needs during vehicle start-up, navigation, and driving. In some embodiments, the battery device 200 consists of one or more battery packs, which can be connected in series, parallel, or a hybrid configuration, where a hybrid configuration refers to the simultaneous presence of series and parallel connections in the connection of multiple battery packs. In another embodiment, the battery device 200 is a cluster-level battery architecture composed of multiple battery packs connected in series, where the number of battery packs in each cluster is strictly configured according to voltage and capacity requirements. More specifically, the battery unit of the battery device 200 includes multiple batteries, some of which are connected in series to form a cluster that meets a preset power supply voltage requirement, with at least one spare battery among the multiple batteries placed in bypass mode.

[0107] Figure 6The diagram illustrates the structure of a battery pack in some embodiments of this application. The battery pack 200 is disposed inside an electric vehicle and can be installed at the bottom, front, or rear of the vehicle. The battery pack 200 provides power to the electric vehicle, for example, acting as its operating power source. The electric vehicle may also be equipped with a controller and a motor. The controller is used to schedule the battery pack to deliver electrical energy to the motor to meet the power needs of the electric vehicle during starting, navigation, and driving. The battery pack 200, as a rechargeable battery, is the power source for new energy vehicles. The battery pack includes a housing 210 and multiple battery cells housed within the housing 210. The housing 210 provides space for the battery cells and other components, while also providing dustproof, waterproof, and protective functions to the internal components, thereby reducing the adverse effects of external liquids or foreign objects on the effectiveness and performance of the battery cells and other components, effectively extending the service life of the battery pack. The shape of the housing is not limited; for example, it can be a cuboid, cylinder, etc. The material of the housing can also be flexibly selected; for example, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., are all suitable. The battery pack 200 in this embodiment includes multiple battery groups 230, with one battery group 230 disposed in each sub-accommodating space. Each battery group 230 includes multiple stacked battery cells, and the stacking direction of the battery cells can be parallel to the plane of the base plate. The battery pack 200 also includes a battery management system (BMS), a thermal management system, an electrical connection system (high-voltage / low-voltage connectors, wiring harnesses, etc.), structural components (shell, brackets, etc.), and protective components, etc. The above components are placed in the housing 210 and sealed by the cover plate 220, forming a complete functional unit that can directly output electrical energy.

[0108] The Battery Management System (BMS) is used to detect the operating status of the battery pack and its individual cells, and to manage the battery module and its individual cells. The BMS includes a Battery Management Unit (BMU), a Cell Measurement Circuit (CMC), sensors, and several electronic control devices. The BMS includes at least one processor and a memory. The memory can be built into the BMS or externally located outside the BMS. The memory can also be remotely configured and connected to the BMS via a network.

[0109] Optionally, in this embodiment, the BMS can send information such as the target status, actual feedback status, V_bat, V_load, I_main, and current timing step of each relay to the controller 300 in real time via CAN messages at a period of 10ms-100ms, so as to realize the full life cycle monitoring and traceability of the high-voltage circuit.

[0110] This application also provides a battery power-on / off control method, applied to the aforementioned battery management system, such as... Figure 7 As shown, the method includes:

[0111] S702, receiving and responding to the power-on command, instructs the pre-charge relay to close, and repeatedly executes the following steps: acquiring the terminal voltage of the battery and the terminal voltage of the load according to a first preset cycle, and calculating the voltage difference between the terminal voltage of the battery and the terminal voltage of the load; until within the pre-charge time, a first number of consecutive voltage differences are not greater than a first preset threshold, instructing the main positive relay to close; acquiring the feedback signal of the auxiliary contact of the main positive relay; if the feedback signal indicates that the auxiliary contact is in a conducting state, instructing the main negative relay to close; after a first preset time interval, instructing the pre-charge relay to open, so as to complete the high-voltage power-on operation;

[0112] S704 receives and responds to the power-down command, and repeatedly executes the following steps: acquires the second current value of the current sensor according to the third preset period; until the second current value is not greater than the third preset threshold for a third consecutive number of times within the third preset time period, then instructs the main negative relay to disconnect; after an interval of the second preset time period, instructs the main positive relay to disconnect, so as to complete the high voltage power-down operation.

[0113] Through steps S702-S704 above, after the pre-charge relay closes, the voltage difference between the battery terminal voltage and the load terminal voltage is monitored. The main positive relay is then controlled to close only when this voltage difference is lower than a preset safety threshold, instead of controlling the main positive relay to close synchronously with the pre-charge relay or after a fixed delay. This solves the technical problem in related technologies where the main relay closing instant generates a surge current far exceeding the rated operating current, leading to contact erosion, adhesion, or even welding. Moreover, compared to a simple fixed delay, the above technical solution in this application uses voltage difference monitoring for closed-loop determination, which can adapt to load capacitance differences and pre-charge circuit aging. Furthermore, a dynamic voltage difference monitoring scheme is proposed, which continuously verifies the voltage difference over multiple cycles, closing the main positive relay only when all voltage differences are lower than the preset safety threshold. Compared to the technical solution that uses instantaneous voltage difference to determine pre-charge completion, the above scheme in this application improves pre-charge reliability. Through the above-mentioned graded closure scheme of the main relay, it can be ensured that both the positive and negative terminals of the high-voltage main circuit supply power to the load through low-impedance main contacts, improving the stability of the high-voltage load power supply to the entire vehicle. Furthermore, by performing a secondary confirmation of the main relay's closed state, it can be ensured that both the positive and negative terminals of the high-voltage main circuit supply power to the load through the low-impedance main contacts, thus improving the stability of the vehicle's high-voltage load power supply. In addition, after a first preset interval, the pre-charge relay is then controlled to open, allowing the current to be fully carried by the main circuit to complete the high-voltage energization, achieving the technical effects of improving high-voltage energization safety and reducing circuit voltage drop. Moreover, using zeroing the circuit current as a prerequisite for power-down disconnection, and controlling the sequence of disconnecting the main negative relay first and then the main positive relay after a delay, ensures that the circuit energy has been discharged to a safe level during disconnection, eliminating arcing at the source. This solves the technical problem in related technologies where directly disconnecting the main positive relay during power-down can cause high-voltage arcing due to the current in the circuit.

[0114] Corresponding to the application scenario of the relay control method provided in the embodiments of this application, the embodiments of this application also provide a battery power-on / off control device, such as... Figure 8 The diagram shown is a structural block diagram of a battery power-on / off control device according to an embodiment of this application, comprising:

[0115] The first indication module 82 is used to receive and respond to a power-on command, instruct the pre-charge relay to close, and repeatedly execute the following steps: collect the terminal voltage of the battery and the terminal voltage of the load according to a first preset period, and calculate the voltage difference between the terminal voltage of the battery and the terminal voltage of the load; until the voltage difference is not greater than a first preset threshold for a first number of consecutive times within the pre-charge time, instruct the main positive relay to close; obtain the feedback signal of the auxiliary contact of the main positive relay; if the feedback signal indicates that the auxiliary contact is in a conducting state, instruct the main negative relay to close; after a first preset time interval, instruct the pre-charge relay to open to complete the high-voltage power-on operation;

[0116] The second indicator module 84 is used to receive and respond to the power-down command, and repeatedly execute the following steps: collect the second current value of the current sensor according to the third preset period; until the second current value is not greater than the third preset threshold for a third consecutive number of times within the third preset time period, then instruct the main negative relay to disconnect; after the second preset time period, instruct the main positive relay to disconnect, so as to complete the high voltage power-down operation.

[0117] pass Figure 8 The device described herein monitors the voltage difference between the battery terminal voltage and the load terminal voltage after the precharge relay closes. It only controls the main positive relay to close when this voltage difference is below a preset safety threshold, instead of controlling the main positive relay to close synchronously with the precharge relay or after a fixed delay. This solves the technical problem in related technologies where the main relay closing instant generates a surge current far exceeding the rated operating current, leading to contact erosion, adhesion, or even welding. Furthermore, compared to a simple fixed delay, the above-described technical solution in this application uses voltage difference monitoring for closed-loop determination, which can adapt to load capacitance differences and precharge circuit aging. In addition, a dynamic voltage difference monitoring scheme is proposed, which continuously verifies the voltage difference over multiple cycles, closing the main positive relay only when all voltage differences are below the preset safety threshold. Compared to the technical solution that uses instantaneous voltage difference to determine precharge completion, the above-described scheme in this application improves precharge reliability. Through the above-described graded closure scheme of the main relay, it is ensured that both the positive and negative terminals of the high-voltage main circuit supply power to the load through low-impedance main contacts, improving the stability of the high-voltage load power supply to the entire vehicle. Furthermore, by performing a secondary confirmation of the main relay's closed state, it can be ensured that both the positive and negative terminals of the high-voltage main circuit supply power to the load through the low-impedance main contacts, thus improving the stability of the vehicle's high-voltage load power supply. In addition, after a first preset interval, the pre-charge relay is then controlled to open, allowing the current to be fully carried by the main circuit to complete the high-voltage energization, achieving the technical effects of improving high-voltage energization safety and reducing circuit voltage drop. Moreover, using zeroing the circuit current as a prerequisite for power-down disconnection, and controlling the sequence of disconnecting the main negative relay first and then the main positive relay after a delay, ensures that the circuit energy has been discharged to a safe level during disconnection, eliminating arcing at the source. This solves the technical problem in related technologies where directly disconnecting the main positive relay during power-down can cause high-voltage arcing due to the current in the circuit.

[0118] This application also provides an electronic device, such as... Figure 9 As shown, the electronic device 90 includes a memory 901 and a processor 902. The memory 901 stores a computer program that can run on the processor 902. When the processor 902 executes the computer program, it implements the method described in the above embodiments. The number of memories 901 and processors 902 can be one or more.

[0119] The electronic device also includes:

[0120] The communication interface 903 is used to communicate with external devices and exchange and transmit data.

[0121] If the memory 901, processor 902, and communication interface 903 are implemented independently, they can be interconnected via a bus to communicate with each other. This bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. This bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 9 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0122] Optionally, in a specific implementation, if the memory 901, processor 902, and communication interface 903 are integrated on a single chip, then the memory 901, processor 902, and communication interface 903 can communicate with each other through an internal interface.

[0123] This application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method provided in this application.

[0124] This application also provides a chip including a processor for calling and executing instructions stored in a memory, causing a communication device with the chip installed to perform the method provided in this application.

[0125] This application also provides a chip, including: an input interface, an output interface, a processor, and a memory. The input interface, output interface, processor, and memory are connected through an internal connection path. The processor is used to execute code in the memory. When the code is executed, the processor is used to execute the method provided in the application embodiment.

[0126] It should be understood that the aforementioned processor can be a Central Processing Unit (CPU), or other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. General-purpose processors can be microprocessors or any conventional processor. It is worth noting that the processor can be a processor supporting Advanced Reduced Instruction Set Machines (ARM) architecture.

[0127] Further, optionally, the aforementioned memory may include read-only memory and random access memory. The memory may be volatile memory or non-volatile memory, or may include both. Non-volatile memory may include read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory may include random access memory (RAM), which serves as an external cache. By way of example, but not limitation, many forms of RAM are available. Examples include Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDR SDRAM), Enhanced Synchronous DRAM (ESDRAM), Sync Link DRAM (SLDRAM), and Direct Rambus RAM (DR RAM).

[0128] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions according to this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another.

[0129] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0130] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0131] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process. Furthermore, the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functionality involved.

[0132] The logic and / or steps described in the flowchart or otherwise herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus or device (such as a computer-based system, a processor-included system or other system that can fetch and execute instructions from, an instruction execution system, apparatus or device).

[0133] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. All or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware, the program being stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiments.

[0134] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. This storage medium can be a read-only memory, a disk, or an optical disk, etc.

[0135] The above description is merely an exemplary embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope described in this application, and these should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A battery management system, characterized in that, The battery management system is communicatively connected to the battery power distribution unit, which is connected in series between the battery and the load. A current sensor is connected to the output of the battery power distribution unit. The battery power distribution unit includes a high-voltage main circuit and a pre-charge circuit. The high-voltage main circuit includes a main positive relay and a main negative relay. The pre-charge circuit includes a pre-charge relay. The battery management system is configured as follows: Upon receiving and responding to a power-on command, the precharge relay is instructed to close, and the following steps are repeated: The terminal voltage of the battery and the terminal voltage of the load are collected according to the first preset cycle, and the voltage difference between the terminal voltage of the battery and the terminal voltage of the load is calculated. Until, within the pre-charge time, a first number of consecutive voltage differences are not greater than a first preset threshold, the main positive relay is instructed to close. Obtain the feedback signal from the auxiliary contact of the main positive relay; If the feedback signal indicates that the auxiliary contact is in a conducting state, then it indicates that the main negative relay is closed; After a first preset time interval, the pre-charge relay is instructed to disconnect to complete the high-voltage power-on operation.

2. The battery management system according to claim 1, characterized in that, Before instructing the precharge relay to close, the battery management system is also configured to: The main negative relay is instructed to close to establish a detection circuit for acquiring the terminal voltage of the battery and the terminal voltage of the load.

3. The battery management system according to claim 2, characterized in that, The battery management system is also configured to: If the voltage difference obtained within the pre-charge time is greater than the first preset threshold, the pre-charge relay and the main negative relay are instructed to disconnect, and a first fault is reported.

4. The battery management system according to claim 2, wherein the battery management system is further configured to: Repeat the following steps: The first current value of the current sensor is acquired according to the second preset cycle; If, within the pre-charge time, a second number of consecutive first current values ​​are greater than a second preset threshold, the pre-charge relay and the main negative relay are instructed to disconnect, and a second fault is reported.

5. The battery management system according to claim 1, characterized in that, The battery management system is also configured to: For any target relay among the main positive relay, the main negative relay, and the precharge relay, obtain the type of the currently closed relay before instructing the target relay to perform a closing operation; Based on the currently closed relay type and the target relay type, the verification result of the target relay is searched in a two-dimensional verification matrix. The column dimension of the two-dimensional verification matrix represents the relay type in the closed state, and the row dimension represents the relay type to be closed. Each cell in the two-dimensional verification matrix is ​​configured with an access control identifier, which includes an access control identifier and a prohibition on closing. If the verification result indicates that closure is allowed, then the target relay is instructed to close.

6. The battery management system according to any one of claims 1 to 5, characterized in that, After instructing the pre-charge relay to disconnect to complete the high-voltage power-on operation, the battery management system is further configured to: Upon receiving and responding to the power-down command, repeat the following steps: The second current value of the current sensor is acquired according to the third preset cycle; Until a third consecutive number of the second current values ​​are not greater than a third preset threshold within a third preset time period, the main negative relay is instructed to disconnect. After a second preset time interval, the main positive relay is instructed to disconnect to complete the high-voltage power-down operation.

7. The battery management system according to claim 6, characterized in that, The battery management system is also configured to: If the second current value is greater than the third preset threshold within the third preset time period, the main positive relay and the main negative relay are instructed to disconnect, and a third fault is reported.

8. The battery management system according to claim 6, characterized in that, The battery management system is also configured to: Monitor the rate at which the terminal voltage of the load drops to a fourth preset threshold; If the rate is less than the fifth preset threshold, the precharge relay is instructed to close. At a fourth preset time interval, the precharge relay is instructed to disconnect.

9. An electric vehicle, characterized in that, include: A controller and a battery device, the battery device comprising one or more battery packs, the battery pack comprising a battery management system, a battery pack, and a battery power distribution unit as described in any one of claims 1 to 8; After receiving the instruction sent by the controller, the battery management system controls the battery power distribution unit according to the instruction type.

10. A method for controlling the power-on and power-off of a battery, characterized in that, The battery management system according to any one of claims 1 to 8 comprises: Upon receiving and responding to a power-on command, the pre-charge relay is instructed to close, and the following steps are repeated: the terminal voltage of the battery and the terminal voltage of the load are collected according to a first preset cycle, and the voltage difference between the terminal voltage of the battery and the terminal voltage of the load is calculated; until a first number of consecutive voltage differences are not greater than a first preset threshold within the pre-charge time, the main positive relay is instructed to close; the feedback signal of the auxiliary contact of the main positive relay is obtained; if the feedback signal indicates that the auxiliary contact is in a conducting state, the main negative relay is instructed to close; after a first preset time interval, the pre-charge relay is instructed to open to complete the high-voltage power-on operation; Upon receiving and responding to a power-down command, the system repeatedly executes the following steps: acquiring the second current value of the current sensor according to a third preset cycle; until, within a third preset time period, a third consecutive number of the second current values ​​are not greater than a third preset threshold, then instructing the main negative relay to disconnect; after a second preset time interval, instructing the main positive relay to disconnect, thereby completing the high-voltage power-down operation.

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