A protection circuit, a control method of the protection circuit and an electric vehicle

Abstract

The application relates to a protection circuit, a control method of the protection circuit and an electric vehicle, and relates to the technical field of vehicle safety. A sampling circuit and an active fuse of the protection circuit are connected in series in a power supply circuit of a battery pack; the sampling circuit outputs a voltage detection signal to a comparison circuit, the voltage detection signal representing the current size in the power supply circuit; the comparison circuit compares the voltage detection value with a voltage reference value and outputs a comparison level to a controller, the comparison level being a first level when the voltage detection value is greater than or equal to the voltage reference value; a current detection circuit is used for obtaining a detection result of the current value in the power supply circuit; the controller controls a driving circuit to blow the active fuse when the comparison level is the first level and the current in the power supply circuit is greater than a preset current according to the detection result of the current value. When an abnormally large current appears in the power supply circuit, the scheme can quickly and timely cut off the power supply circuit of the power battery pack to the latter circuit, and has high reliability and high safety.

Description

Technical Field

[0001] This application relates to the field of vehicle safety technology, and in particular to a protection circuit, a control method for the protection circuit, and an electric vehicle. Background Technology

[0002] Electric vehicles are generally powered by battery packs. Due to factors such as range and load performance, the voltage of the battery packs far exceeds the safe voltage for the human body. Currently, electric vehicles can use 400V systems, and in the future, they will evolve towards 800V or higher voltage systems. Therefore, a safe and reliable battery system is very important, especially in the event of an emergency, to ensure that the electrical connection between the battery pack and the external load can be safely disconnected.

[0003] In existing technologies, relays or traditional fuses are often used to disconnect the external power supply lines of the power battery pack. However, when an abnormally large current occurs in the power supply line, such as when a collision causes an external load short circuit, resulting in a large current in the circuit, the relay may stick together, preventing the external power supply line from being disconnected. Furthermore, the fuse requires a certain amount of time to accumulate heat before it can blow, so it may not be able to disconnect the power supply line in time.

[0004] In summary, the current solution suffers from poor reliability and low security. Summary of the Invention

[0005] To address the aforementioned technical problems in the existing technology, this application provides a protection circuit, a control method for the protection circuit, and an electric vehicle. When an abnormally large current occurs in the power supply line, the power supply line from the power battery pack to the downstream circuit can be quickly and promptly cut off, exhibiting high reliability and high safety.

[0006] Firstly, this application provides a protection circuit for timely disconnecting the power battery pack from the power supply line when an overcurrent occurs. The protection circuit includes: a sampling circuit, a comparison circuit, an active fuse, a current detection circuit, a drive circuit, and a controller. The sampling circuit and the active fuse are connected in series in the power supply line of the battery pack. The sampling circuit outputs a voltage detection signal to the comparison circuit, which represents the magnitude of the current in the power supply line. The comparison circuit compares the detected voltage value with a voltage reference value and outputs a comparison level to the controller. When the detected voltage value is greater than or equal to the voltage reference value, the comparison level is a first level. The current detection circuit acquires the detection result of the current value in the power supply line. The controller, when the comparison level is the first level and the current in the power supply line is determined to be greater than a preset current based on the current detection result, controls the drive circuit to detonate the active fuse.

[0007] In this solution, a sampling circuit and a comparison circuit are used to detect whether there is an abnormally large current in the power supply line. When an abnormally large current is detected, the controller further makes a secondary judgment based on the current value detected by the current detection circuit, effectively avoiding false triggering and ensuring high reliability. When the comparison level is at the first level and the controller determines that the current in the power supply line is greater than the preset current based on the current value detection result, it controls the drive circuit to detonate the active fuse, quickly and timely cutting off the power supply line from the power battery pack to the downstream circuit. This solution quickly cuts off the main high-voltage circuit in overcurrent scenarios. It can protect the high-voltage electrical appliances of the entire vehicle and the relays on the main circuit, avoiding the sticking failure caused by the relays being cut off under load, resulting in strong safety and high reliability. In addition, this application solution is an active control system. By detonating the active fuse, the power supply line can be quickly cut off in a short time. The tripping time of the active fuse is generally in the millisecond range, which is significantly shorter than the time taken by the passive melting of the fuse in the prior art. This reduces the safety hazards caused by the continuous presence of large current in the power supply line and improves safety.

[0008] In one possible implementation, the sampling circuit specifically includes a sampling resistor and a differential amplifier circuit. The sampling resistor is connected in series in the power supply line, with its first end connected to the first end of the differential amplifier circuit and its second end connected to the second end of the differential amplifier circuit. The output of the differential amplifier circuit is used to output the detected voltage value to the first end of the comparator circuit.

[0009] In one possible implementation, the protection circuit further includes a first isolator; a first end of the first isolator is connected to the controller, and a second end of the first isolator is connected to the drive circuit; the first isolator is used to isolate the controller from the drive circuit and to provide isolated communication between the controller and the drive circuit.

[0010] The controller at the first end of the isolation circuit is in a low-voltage region, while the drive circuit at the second end of the first isolator is in a high-voltage region. The first isolator can isolate the controller from the high-voltage region to protect the controller.

[0011] In one possible implementation, the protection circuit further includes a power supply circuit for powering the drive circuit, the first isolator, the controller, the sampling circuit, and the comparator circuit. The power supply circuit includes a transformer, a step-down isolation circuit, and a rectifier circuit. The primary side of the transformer is connected to the power battery pack via the step-down isolation circuit, and the secondary side of the transformer is connected to the output terminal of the power supply circuit via the rectifier circuit.

[0012] In this implementation, the power supply for the protection circuit is obtained from the power battery pack of the electric vehicle, rather than from the low-voltage battery of the electric vehicle. This ensures that the input voltage of the protection circuit is not affected by the voltage fluctuations of the low-voltage battery, making the power supply of the protection circuit more stable and ensuring that the protection circuit can work normally.

[0013] In one possible implementation, the protection circuit also includes a current limiting control circuit; the current limiting control circuit is connected to the output terminal of the power supply circuit; the current limiting control circuit is used to cut off the external power supply line of the power supply circuit when an overcurrent occurs in the output current of the power supply circuit.

[0014] An overcurrent in the power supply circuit output may be caused by a short circuit in the subsequent circuit, such as a short circuit within the drive circuit.

[0015] In one possible implementation, the first terminal of the active fuse is connected to the power battery pack, and the second terminal of the active fuse is connected to the downstream circuit. The protection circuit also includes a diagnostic circuit and a second isolator. The first terminal of the diagnostic circuit is connected to the second terminal of the active fuse. The second terminal of the diagnostic circuit is connected to the second isolator. The output terminal of the current detection circuit is connected to the second isolator. The output terminal of the comparison circuit is connected to the second isolator. The diagnostic circuit is used to determine whether the active fuse is open based on the voltage at the first terminal. The second isolator is used to isolate and transmit the detection result of the current detection circuit, the diagnostic result of the diagnostic circuit, and the comparison level output of the comparison circuit to the controller.

[0016] In one possible implementation, the drive circuit is also used to detect the impedance of the active fuse to determine whether the active fuse is in good condition.

[0017] In one possible implementation, the controller is the controller of the battery management system (BMS).

[0018] Secondly, this application also provides a control method for a protection circuit, applied to the protection circuit provided by the first aspect and any implementation thereof, the method comprising: when the comparison level is a first level and the current in the power supply line is determined to be greater than a preset current based on the detection result of the current value, controlling the drive circuit to detonate an active fuse.

[0019] Thirdly, this application also provides an electric vehicle, which includes the protection circuit provided in the first aspect and any implementation thereof, and further includes a power battery pack and a power supply line. The protection circuit is used to detonate an active fuse to disconnect the power battery pack from the power supply line when an overcurrent occurs in the power supply line. Attached Figure Description

[0020] Figure 1 A schematic diagram of an electrical system for an electric vehicle provided in this application;

[0021] Figure 2 A schematic diagram of a protection circuit provided in an embodiment of this application;

[0022] Figure 3A schematic diagram of another protection circuit provided in an embodiment of this application;

[0023] Figure 4 A flowchart illustrating a control method for a protection circuit provided in an embodiment of this application;

[0024] Figure 5 This is a schematic diagram of an electric vehicle provided in an embodiment of this application. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present application, the application scenarios of the present application are described below.

[0026] See Figure 1 The figure is a schematic diagram of an electric vehicle electrical system provided in this application.

[0027] The electrical system of the electric vehicle shown in the diagram mainly includes a motor controller 10, a motor 20, a power battery pack 30, a high-voltage distribution box 40, a DC / DC converter circuit 50, a low-voltage battery 60, a DC charging circuit 70, and an on-board charger 80.

[0028] The power battery pack 30 provides high-voltage direct current (VDC) to the electric vehicle. A portion of this VDC is converted to alternating current (AC) via the high-voltage distribution box 40 and the motor controller 10, supplying the motor 20 to drive the electric vehicle. Another portion of the VDC is converted to low-voltage direct current via the high-voltage distribution box 40 and the DC / DC converter circuit 50, supplying the low-voltage battery 60 and / or the low-voltage system of the electric vehicle. The high-voltage distribution box 40 can also be referred to as a power distribution unit (PDU).

[0029] When an electric vehicle is charging, in some embodiments, the electric vehicle charges the power battery pack 30 through a DC charging circuit 70. At this time, the DC charging circuit 70 is connected to a DC charging pile. This charging method is also called "DC fast charging". DC fast charging has a larger charging power.

[0030] In other embodiments, the electric vehicle is charged via an on-board charger 80, which is connected to an AC charging station or the AC power grid. Some on-board chargers 80 can also simultaneously charge the low-voltage battery 60.

[0031] The positive and negative terminals of the power battery pack 30 are supplied to the outside through a high-voltage power supply line. When the vehicle is short-circuited due to a malfunction or collision, a large short-circuit current may occur in the power supply line. Therefore, it is necessary to disconnect the electrical connection between the power battery pack and the external load in time, such as disconnecting the electrical connection between the power battery pack 30 and the high-voltage distribution box 40.

[0032] In existing technologies, relays or traditional fuses are often used to disconnect the external power supply lines of the power battery pack. However, relays may stick together when there is a large current in the circuit, making it impossible to disconnect the external power supply lines. Fuses require a certain amount of time to accumulate heat before they can blow, so they may not be able to disconnect the power supply lines in time.

[0033] To address the above issues, this application provides a protection circuit, a control method for the protection circuit, and an electric vehicle. Using this solution, when an abnormally high current is detected in the power supply line, the controller can control the drive circuit to detonate an active fuse. The tripping time of the active fuse is typically in the millisecond range, significantly shorter than the time required for passive fuse blowing in existing technologies. This reduces the safety hazards caused by continuously high current in the power supply line and improves safety. This solution quickly disconnects the main high-voltage circuit in overcurrent scenarios. It can protect the high-voltage electrical appliances of the entire vehicle and the relays in the main circuit, avoiding the sticking fault caused by relays disconnecting under load. It offers strong safety and high reliability.

[0034] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0035] The terms "first" and "second" used in this application description are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0036] In this application, unless otherwise expressly specified and limited, the term "connection" shall be interpreted broadly. For example, "connection" may be a fixed connection, a detachable connection, or an integral part; it may be a direct connection or an indirect connection through an intermediate medium.

[0037] See Figure 2 The figure is a schematic diagram of a protection circuit provided in an embodiment of this application.

[0038] The protection circuit provided in this application embodiment includes: a controller 101, a sampling circuit 103, a comparison circuit 102, a drive circuit 104, an active fuse 105, and a current detection circuit 106.

[0039] The sampling circuit 103 and the active fuse 105 are connected in series in the power supply line of the battery pack. In practical applications, the positive and negative terminals of the power battery pack are connected to the power supply line respectively. In this embodiment, only one active fuse 105 may be provided, for example, in series in the power supply line of the positive terminal or the power supply line of the negative terminal. Alternatively, two fuses may be provided, one in the power supply line of the positive terminal and one in the power supply line of the negative terminal. This redundancy ensures that the power supply line can be disconnected in a timely manner.

[0040] The sampling circuit 103 is used to output a voltage detection signal to the comparison circuit 102. The voltage detection signal represents the magnitude of the current in the power supply line.

[0041] The comparator circuit 102 compares the detected voltage value with a voltage reference value and outputs a comparison level to the controller 101. Specifically, when the detected voltage value is greater than or equal to the voltage reference value, the comparison level is a first level; when the detected voltage value is less than the voltage reference value, the comparison level is a second level. For ease of explanation, the following description of this embodiment will use an example where the first level is high and the second level is low.

[0042] The current detection circuit 106 is used to obtain the detection result of the current value in the power supply line and send the detection result of the current value to the controller 101. In one possible implementation, the current detection circuit 106 may include a detection chip.

[0043] The controller 101 can be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), a digital signal processor (DSP), or a combination thereof. The PLD can be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof; this application does not impose specific limitations on the implementation.

[0044] In one possible implementation, controller 101 is set up independently to implement the control functions in the technical solutions of this application embodiment. In another possible implementation, controller 101 may also reuse an existing controller to reduce hardware costs; for example, controller 101 may be a controller of a battery management system (BMS).

[0045] When the comparison level is the first level and the current in the power supply line is determined to be greater than the preset current based on the current value detection result, the controller 101 controls the drive circuit 104 to detonate the active fuse 105.

[0046] In one possible implementation, the active fuse 105 uses a gunpowder explosion to actively and quickly disconnect. When the drive circuit 104 receives a control signal from the controller 101 instructing the active fuse 105 to detonate, it outputs a constant current source to cause the gunpowder in the active fuse 105 to explode. The disconnection process of the active fuse 105 is relatively fast, completing within milliseconds, significantly reducing the time required to disconnect the circuit compared to a traditional fusible fuse.

[0047] When the controller 101 determines that an abnormally large current has occurred in the power supply line based on the level output of the comparison circuit 102, it further performs a secondary redundant judgment based on the current value detection result of the current detection circuit 106, which effectively avoids false triggering and has high reliability.

[0048] In one possible implementation, the controller 101 will trigger an interrupt upon receiving a high-level output from the comparator circuit 102, and will not trigger an interrupt upon receiving a low-level output from the comparator circuit 102. Therefore, when the comparator circuit 102 outputs a high-level signal, the controller 101 is interrupted, causing the controller 101 to determine whether the current value detected by the current detection circuit 106 is greater than the preset current. If so, the controller 101 will control the drive circuit 104 to cut off the active fuse 105.

[0049] In summary, the solution provided by the embodiments of this application can quickly and timely cut off the power supply line from the power battery pack to the downstream circuit when an abnormally large current occurs in the power supply line, thus exhibiting high reliability and high safety.

[0050] The following section explains the specific implementation of the protection circuit.

[0051] See Figure 3 This figure is a schematic diagram of another protection circuit provided in an embodiment of this application.

[0052] The protection circuit provided in the embodiments of this application is... Figure 2 The difference is that it also includes a first isolator 107, a power supply circuit 108, a current limiting control circuit 109, a diagnostic circuit 110, and a second isolator 111.

[0053] Figure 3 The sampling circuit 103 specifically includes a sampling resistor R0 and a differential amplifier circuit.

[0054] The differential amplifier circuit includes resistors R1, R2, R3, R4 and operational amplifier U1.

[0055] The sampling resistor R0 is connected in series in the power supply line. The first end of the sampling resistor R0 is connected to the first end of the differential amplifier circuit, and the second end of the sampling resistor R0 is connected to the second end of the differential amplifier circuit.

[0056] The first terminal of R1 is connected to the first terminal of the differential amplifier circuit, and the second terminal of R1 is connected to the inverting input terminal of U1; the first terminal of R2 is connected to the second terminal of the differential amplifier circuit, and the second terminal of R2 is connected to the non-inverting input terminal of U1.

[0057] The output of the differential amplifier circuit is used to output the voltage detection value to the first terminal of the comparator circuit 102. The amplification gain of the differential amplifier circuit is gain = R4 / R1. In one possible implementation, the resistance values ​​of R1 and R2 are the same, and the resistance values ​​of R3 and R4 are the same.

[0058] The comparator circuit 102 includes a voltage divider circuit and a comparator U2. In this embodiment, the voltage divider circuit including voltage divider resistors R5 and R6 is used as an example for explanation. VCC is the DC power supply provided by the power supply circuit 106. The non-inverting input of U2 is connected to the voltage reference value, which is the voltage divided by R5. The inverting input of U2 is connected to the voltage detection value output by the sampling circuit, which is the voltage output by U1.

[0059] The first terminal of the first isolator 107 is connected to the controller 101, and the second terminal of the first isolator is connected to the drive circuit 104. The first isolator 107 is used to isolate the controller 101 from the drive circuit 104 and to provide isolated communication between the controller and the drive circuit. In one possible implementation, the controller 101 and the drive circuit 104 communicate based on the Serial Peripheral Interface (SPI) protocol.

[0060] The controller 101 at the first end of the first isolator 107 is in a low-voltage region, and the active fuse 105 controlled by the drive circuit 104 at the second end of the first isolator 107 is in a high-voltage region. Therefore, the drive circuit 104 is generally located in a high-voltage region. The first isolator 107 can isolate the controller 101 from the high-voltage region to protect the controller 101.

[0061] The protection circuit also includes a power supply circuit 108, which provides a stable low-voltage DC power supply to the drive circuit 104, the first isolator 107, the controller 101, the sampling circuit 103, and the comparator circuit 102.

[0062] The power supply circuit 108 in this embodiment includes a transformer T, an isolation step-down circuit 1081, and a rectifier circuit 1082. The primary side of the transformer T is connected to the power battery pack 30 through the isolation step-down circuit 1081, and the secondary side of the transformer T is connected to the output terminal of the power supply circuit 108 through the rectifier circuit 1082. The isolation step-down circuit 1081 is used to step down the high-voltage DC power output from the power battery pack 30. The ratio of the number of turns in the primary winding to the number of turns in the secondary winding of the transformer T is greater than 1, thereby achieving voltage reduction.

[0063] The rectifier circuit 1082 can be either a diode rectifier circuit or a synchronous rectifier circuit. The synchronous rectifier circuit uses a MOSFET with extremely low on-state resistance to replace the rectifier diode, thereby improving power conversion efficiency and reducing energy loss.

[0064] The power supply circuit 108 obtains DC power from the power battery pack of the electric vehicle, rather than from the low-voltage battery of the electric vehicle. This ensures that the input voltage of the protection circuit is not affected by the voltage change of the low-voltage battery, making the power supply of the protection circuit more stable and ensuring that the protection circuit can work normally.

[0065] Furthermore, the protection circuit also includes a current limiting control circuit 109, which is connected to the output terminal of the power supply circuit 108. The current limiting control circuit 109 is used to cut off the external power supply line of the power supply circuit 108 when an overcurrent occurs in the output current of the power supply circuit 108.

[0066] The overcurrent output by the power supply circuit 108 may be caused by a short circuit in the subsequent circuit, such as a short circuit in the drive circuit 104. In this case, the current limiting control circuit 109 can disconnect the connection between the rectifier circuit 1082 and the drive circuit 104.

[0067] The active fuse 105 is connected in series on the high-voltage power supply line. That is, the first end of the active fuse 105 is connected to the power battery pack, and the second end of the active fuse is connected to the downstream circuit.

[0068] The first terminal of the diagnostic circuit 110 of the protection circuit is connected to the second terminal of the active fuse 105, and the second terminal of the diagnostic circuit 110 is connected to the controller 101. The diagnostic circuit 110 can diagnose the high-voltage status of the power supply line and the status of the active fuse 105. For example, the diagnostic circuit 110 can determine whether the active fuse 105 has been opened based on the voltage at the first terminal.

[0069] If the active fuse 105 blows, an open circuit occurs in the power supply line. Since the first terminal of the diagnostic circuit 110 is connected to the second terminal of the active fuse 105, a low-level signal will be detected at the first terminal. If the active fuse 105 does not blow, a high-level signal will be detected at the first terminal.

[0070] The controller 101 can determine whether the active fuse 105 has been successfully detonated based on the diagnostic results of the diagnostic circuit 110. If the voltage at the first terminal is high, it indicates that the detonation was unsuccessful. At this time, the controller 101 can control the drive circuit 104 to detonate the active fuse 105 again.

[0071] The drive circuit 104, diagnostic circuit 110, and controller 101 can detect the impedance of the active fuse 105 to determine whether the active fuse 105 is in good condition. In one possible implementation, the controller 101 can control the drive circuit 104 to periodically detect the impedance value of the active fuse 105. If an abnormal impedance value is detected, it indicates that the active fuse 105 needs to be replaced. At this time, the controller 101 can send an instruction to the vehicle control unit (VCU) so that the VCU can prompt the user. When detecting the impedance value of the active fuse 105, a small signal injection method can be used. The drive circuit 104 outputs an excitation signal to the active fuse 105, and the impedance is determined based on the detected response signal.

[0072] The second terminal of the diagnostic circuit 110 is connected to the second isolator 111, the output terminal of the current detection circuit 106 is connected to the second isolator 111, and the output terminal of comparator U2 of the comparison circuit 102 is connected to the second isolator 111. The second isolator 111 is used to isolate and transmit the detection result of the current detection circuit 106, the diagnostic result of the diagnostic circuit 110, and the comparison level output by the comparison circuit 102 to the controller 101.

[0073] In summary, the solution provided by the embodiments of this application can quickly and promptly disconnect the power supply line from the power battery pack to the downstream circuit when an abnormally large current occurs in the power supply line, exhibiting high reliability and high safety. Furthermore, the solution of this application isolates the controllers on the high-voltage and low-voltage sides through a first isolator, provides a reliable and stable power supply to the protection circuit using the power supply circuit, and can detect whether the active fuse 105 is in good condition, further improving the reliability and safety of the protection circuit.

[0074] Based on the protection circuit provided in the above embodiments, this application also provides a control method for the protection circuit, which will be described in detail below with reference to the accompanying drawings.

[0075] See Figure 4 The figure is a flowchart of a control method for a protection circuit provided in an embodiment of this application.

[0076] This method can be applied to control the protection circuit in the above embodiments. For details on the specific implementation and working principle of the protection circuit, please refer to the above description, which will not be repeated here. This method can be implemented by the controller of the protection circuit, and includes the following steps:

[0077] S11: Switch that enables the power supply circuit.

[0078] S11 is generally activated when the vehicle's high-voltage system is powered on. In other words, the protection circuit is usually activated when the vehicle's high-voltage system is powered on. At this time, the power circuit begins to convert the high voltage of the power battery pack into low voltage to power the protection circuit.

[0079] S12: Diagnose the connection status of the active fuse.

[0080] The controller controls the drive circuit to detect the impedance of the active fuse to determine its connection status. If the impedance is normal, it indicates that the active fuse is in a normal connection state. If the impedance is abnormally high, it indicates that the active fuse is in an abnormal state, possibly with an open circuit, and needs to be replaced.

[0081] When detecting the impedance value of the active fuse 105, a small signal injection method can be used. The drive circuit 104 outputs an excitation signal to the active fuse 105, and the impedance is determined based on the detected response signal.

[0082] Furthermore, the controller can also determine whether the active fuse is properly connected based on the diagnostic results of the diagnostic circuit. If the active fuse is open, an open circuit occurs in the power supply line. In this case, since the first terminal of the diagnostic circuit is connected to the second terminal of the active fuse, the first terminal will be detected as low. If the active fuse is not open, the first terminal will be detected as high.

[0083] S13: Determine if the connection status of the active fuse is normal.

[0084] If yes, then execute S14; otherwise, execute S18.

[0085] S14: Whether the received level signal output by the comparator circuit is high.

[0086] If yes, it indicates that there may be an abnormally large current in the power supply line at this time, and S15 is executed; otherwise, S14 is executed to continue to determine whether the received level signal output by the comparison circuit is high.

[0087] S15: Determine whether the detected current value is greater than the preset current.

[0088] If so, it can be determined that there is an abnormally large current in the power supply line at this time, and S16 is executed; otherwise, S14 is executed to continue to determine whether the received level signal output by the comparison circuit is high.

[0089] The controller makes a secondary judgment based on the current value detected by the current detection circuit, which effectively avoids false triggering and ensures high reliability.

[0090] S16: Control drive circuit to detonate active fuse.

[0091] S17: Determine whether the active fuse has been blown based on the diagnostic results of the diagnostic circuit.

[0092] If yes, it indicates that the active fuse disconnection process has been completed, and S18 is executed; otherwise, it indicates that the active fuse has been detonated, and S16 is executed until the active fuse is successfully detonated.

[0093] S18: Report that the active fuse of the main controller has been blown.

[0094] S19: Report an abnormal status of the active fuse on the main controller.

[0095] It is understood that the above division of steps and the order of steps are only for the convenience of explanation and do not constitute a limitation on the technical solution of this application. In actual application, the steps and the order of steps can be adapted, for example, the order of S14 and S15 can be changed.

[0096] In summary, the method provided in this application embodiment can quickly and timely disconnect the power supply line from the power battery pack to the downstream circuit when an abnormally large current occurs in the power supply line, thus exhibiting high reliability and high safety.

[0097] Based on the protection circuit provided in the above embodiments, this application also provides an electric vehicle, which will be described in detail below with reference to the accompanying drawings.

[0098] See Figure 5 The figure is a schematic diagram of an electric vehicle provided in an embodiment of this application.

[0099] The electric vehicle 1000 includes a protection circuit 1001, a power battery pack 30, and a power supply line (not shown in the figure). The protection circuit 1001 is used to detonate an active fuse to disconnect the power battery pack 30 from the power supply line when an overcurrent occurs in the power supply line.

[0100] For details on the specific implementation and working principle of the electric vehicle 1000, please refer to the description in the above embodiments. The embodiments of this application will not be repeated here.

[0101] In this embodiment, a protection circuit 1001 is installed on the electric vehicle. This protection circuit 1001 uses a sampling circuit and a comparison circuit to detect whether an abnormally large current occurs in the power supply line. When an abnormally large current occurs, the controller further performs a secondary judgment based on the current value detection result of the current detection circuit, effectively avoiding false triggering and ensuring high reliability. When the comparison level is the first level and the controller determines that the current in the power supply line is greater than the preset current based on the current value detection result, it controls the drive circuit to detonate the active fuse, quickly and timely cutting off the power supply line from the power battery pack to the downstream circuit. This solution quickly cuts off the main high-voltage circuit in overcurrent scenarios. It can protect the high-voltage electrical appliances of the entire vehicle and the relays on the main circuit, avoiding the sticking fault caused by the relays being cut off under load, resulting in strong safety and high reliability.

[0102] Furthermore, the solution proposed in this application is an active control system. By detonating an active fuse, the power supply line can be quickly cut off in a short time. The tripping time of the active fuse is generally in the millisecond range, which is significantly shorter than the time required for the passive melting of fuses in the prior art. This reduces the safety hazards caused by the continuous presence of large current in the power supply line and improves the safety of electric vehicles.

[0103] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0104] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. The device embodiments described above are merely illustrative, and the units and modules described as separate components may or may not be physically separate. Furthermore, some or all of the units and modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0105] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A protection circuit, characterized in that, The protection circuit includes: a sampling circuit, a comparison circuit, an active fuse, a current detection circuit, a drive circuit, and a controller; The sampling circuit and the active fuse are connected in series in the power supply line of the battery pack; The sampling circuit is used to output a voltage detection signal to the comparison circuit, and the voltage detection signal represents the magnitude of the current in the power supply line; The comparison circuit is used to compare the voltage detection value with the voltage reference value and output a comparison level to the controller, wherein the comparison level is a first level when the voltage detection value is greater than or equal to the voltage reference value; The current detection circuit is used to obtain the detection result of the current value in the power supply line; The controller is configured to control the drive circuit to detonate the active fuse when the comparison level is a first level and the current in the power supply line is determined to be greater than a preset current based on the detection result of the current value.

2. The protection circuit according to claim 1, characterized in that, The sampling circuit specifically includes a sampling resistor and a differential amplifier circuit; The sampling resistor is connected in series in the power supply line, the first end of the sampling resistor is connected to the first end of the differential amplifier circuit, and the second end of the sampling resistor is connected to the second end of the differential amplifier circuit. The output of the differential amplifier circuit is used to output the voltage detection value to the first terminal of the comparator circuit.

3. The protection circuit according to claim 1 or 2, characterized in that, The protection circuit also includes a first isolator; The first end of the first isolator is connected to the controller, and the second end of the first isolator is connected to the drive circuit; The first isolator is used to isolate the controller from the drive circuit and to provide isolated communication between the controller and the drive circuit.

4. The protection circuit according to claim 3, characterized in that, The protection circuit further includes a power supply circuit, which supplies power to the drive circuit, the isolation circuit, the controller, the sampling circuit, and the comparison circuit. The power supply circuit includes a transformer, a step-down isolation circuit, and a rectifier circuit. The primary side of the transformer is connected to the power battery pack through the step-down isolation circuit, and the secondary side of the transformer is connected to the output terminal of the power supply circuit through the rectifier circuit.

5. The protection circuit according to claim 4, characterized in that, The protection circuit also includes a current limiting control circuit; The current limiting control circuit is connected to the output terminal of the power supply circuit; The current limiting control circuit is used to cut off the external power supply line of the power supply circuit when the current output by the power supply circuit is overcurrent.

6. The protection circuit according to claim 1, characterized in that, The first end of the active fuse is connected to the power battery pack, and the second end of the active fuse is connected to the downstream circuit. The protection circuit also includes a diagnostic circuit and a second isolator, wherein the first end of the diagnostic circuit is connected to the second end of the active fuse; The second terminal of the diagnostic circuit is connected to the second isolator; The output terminal of the current detection circuit is connected to the second isolator; The output of the comparator circuit is connected to the second isolator; The diagnostic circuit is used to determine whether the active fuse has been disconnected based on the voltage at the first terminal. The second isolator is used to isolate and transmit the detection result of the current detection circuit, the diagnostic result of the diagnostic circuit, and the comparison level output by the comparison circuit to the controller.

7. The protection circuit according to claim 1, characterized in that, The drive circuit is also used to detect the impedance of the active fuse to determine whether the active fuse is in good condition.

8. The protection circuit according to claim 1, characterized in that, The controller is the controller of the battery management system (BMS).

9. A control method for a protection circuit, characterized in that, The protection circuit includes: a sampling circuit, a comparison circuit, an active fuse, a current detection circuit, and a drive circuit; the sampling circuit and the active fuse are connected in series in the power supply line of the battery pack; the sampling circuit is used to output a voltage detection signal to the comparison circuit, the voltage detection signal representing the magnitude of the current in the power supply line; the comparison circuit is used to compare the voltage detection value with a voltage reference value and output a comparison level, wherein when the voltage detection value is greater than or equal to the voltage reference value, the comparison level is a first level; the current detection circuit is used to obtain the detection result of the current value in the power supply line, and the method includes: When the comparison level is the first level and the current in the power supply line is determined to be greater than the preset current based on the detection result of the current value, the drive circuit is controlled to detonate the active fuse.

10. An electric vehicle, characterized in that, The electric vehicle includes the protection circuit described in any one of claims 1-8, and further includes a power battery pack and a power supply line; The protection circuit is used to detonate the active fuse to disconnect the power battery pack from the power supply line when an overcurrent occurs in the power supply line.

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