Vehicle-mounted DCDC bidirectional isolation switch circuit and control method

Abstract

The application relates to a vehicle-mounted DCDC bidirectional isolation switch circuit and a control method. The switch circuit comprises a DCDC module, a bidirectional switch module, a data transmission interface, a low-voltage main power supply device, a backup low-voltage power supply device and a low-voltage storage battery. The low-voltage output port of the DCDC module is connected with the power input end of the low-voltage main power supply device and the first power connection end of the bidirectional switch module. The second power connection end of the bidirectional switch module is connected with the power input end of the backup low-voltage power supply device and the power input end of the low-voltage storage battery. The DCDC module and the bidirectional switch module transmit corresponding state signals and switch control signals through the data transmission interface. On the basis of reserving the cost advantage of single DCDC and low-voltage storage battery redundant power distribution, the fault isolation capability and power supply continuity between the two low-voltage outputs are improved, so that the low-voltage storage battery can still supply power to the backup low-voltage power supply device after a fault occurs.

Description

Technical Field

[0001] This application relates to the technical field of vehicle-mounted switching circuits, and in particular to a vehicle-mounted DC-DC bidirectional isolation switch circuit and control method. Background Technology

[0002] Currently, onboard DC-DC modules in new energy vehicles convert the high-voltage DC power output from the high-voltage power battery into the low-voltage DC power required by the vehicle's low-voltage system, supplying power to low-voltage electrical equipment such as the vehicle controller, brakes, steering, and intelligent driving VCU. As intelligent driving advances towards Level 3, the functional safety requirements for the vehicle's low-voltage power supply system are continuously increasing. When the DC-DC system experiences output loss, overvoltage, undervoltage, or short-circuit faults, if critical low-voltage equipment loses power, it can easily lead to safety risks such as brake assist failure, abnormal steering control, or disengagement of intelligent driving functions. Therefore, the onboard low-voltage power supply system needs to be able to support the vehicle's safe parking even when the power system fails, and even continue to maintain critical functions under certain conditions.

[0003] like Figures 2-3 As shown, existing vehicle-mounted DC-DC low-voltage power supply solutions mainly include the following categories: The first category is a single DC-DC output connected to a low-voltage 12V battery via a traditional fuse or relay. This solution has a simple structure and can usually only meet the basic functional safety protection requirements. However, its protection method mainly relies on passive hardware action, making it difficult to provide early warning and report faults. The second category is dual DC-DC redundant output, which sets up two independent DC-DC power supply paths. When one DC-DC or its power supply path fails, the other path continues to supply power to the vehicle's low-voltage system. This solution has high safety, but requires two sets of DC-DC power conversion and control structures, resulting in higher cost and system complexity. The third category is a single DC-DC with redundant power distribution to the low-voltage battery, using an electronic fuse (efuse) to control the on / off of the power supply path. When a fault is detected in the main DC-DC or a certain path, the faulty path can be quickly cut off and the battery can maintain power supply. However, this solution still needs to further address issues such as fault isolation between the two low-voltage outputs, fault identification, abnormal current direction judgment, and reliability testing of the isolating switch itself.

[0004] Therefore, existing technologies still suffer from problems such as a single protection method, insufficient fault status feedback, high cost of dual DC-DC converters, and insufficient reliability of single DC-DC redundant power distribution isolation. They are unable to fully meet the needs of the vehicle's low-voltage power supply system for fault isolation, status reporting, and continuous power supply to critical low-voltage equipment under high functional safety levels such as ASIL C / D. Summary of the Invention

[0005] To address the problem that existing vehicle-mounted low-voltage power supply systems struggle to promptly isolate faulty branches, maintain power supply to healthy branches, and meet high functional safety requirements when DCDC output is abnormal or low-voltage power supply branches fail, this application provides a vehicle-mounted DCDC bidirectional isolation switch circuit and control method.

[0006] A vehicle-mounted DC-DC bidirectional isolation switch circuit includes a DC-DC module, a bidirectional switch module, a data transmission interface, a low-voltage main power supply device, a backup low-voltage power supply device, and a low-voltage battery; The low-voltage output port of the DCDC module forms the first low-voltage output port, which is connected to the power input terminal of the low-voltage main power supply equipment and the first power connection terminal of the bidirectional switch module. The second power connection terminal of the bidirectional switch module forms a second low-voltage output port, which is connected to the power input terminal of the backup low-voltage power supply equipment and the power input terminal of the low-voltage battery, respectively. The DC-DC module and the bidirectional switch module transmit corresponding status signals and switch control signals through a data transmission interface. The switch control signal is used to control the bidirectional switch module to turn on or off between the first low-voltage output port and the second low-voltage output port. When the signal acquisition terminal of the DC-DC module detects an abnormal power supply state at the first low-voltage output port or determines an abnormal power supply state at the second low-voltage output port based on the status signal, the DC-DC module controls the bidirectional switch module to disconnect to isolate the first low-voltage output port and the second low-voltage output port. When the signal acquisition terminal of the bidirectional switch module detects an abnormal power supply state at the second low-voltage output port, the bidirectional switch module automatically disconnects to isolate the first low-voltage output port and the second low-voltage output port. After either the first low-voltage output port or the second low-voltage output port is fault-isolated, the low-voltage battery is used to provide low-voltage power to the backup low-voltage power supply equipment.

[0007] By adopting the above technical solutions, when the vehicle low-voltage power supply system experiences abnormalities such as overvoltage, undervoltage, overcurrent, or short circuit on the DCDC side or the backup power supply side, it can promptly disconnect the electrical connection between the faulty branch and the normal branch, preventing the fault from spreading to the other side. At the same time, after the fault is isolated, the low-voltage battery continues to supply power to the backup low-voltage power supply equipment, thereby improving the power supply continuity and functional safety and reliability of the vehicle's key low-voltage loads.

[0008] Preferably, the bidirectional switch module includes a driver chip, an isolating switch unit, and a first overvoltage protection unit. The control signal input terminal of the driver chip is connected to the data transmission interface to acquire the corresponding switch control signal. The drive signal output terminal of the driver chip is connected to the controlled terminal of the isolating switch unit. The data communication terminal of the driver chip is connected to the data transmission interface to send the corresponding status signal. The first conducting terminal of the isolating switch unit is connected to the first low-voltage output port, and the second conducting terminal of the isolating switch unit is connected to the second low-voltage output port. The signal input terminal of the first overvoltage protection unit is connected to the second low-voltage output port, and the signal output terminal of the first overvoltage protection unit is connected to the turn-off signal input terminal of the driver chip.

[0009] By adopting the above technical solution, the bidirectional switch module can receive the switch control signal output by the DCDC module for controlled disconnection, and can also provide a shutdown signal directly to the driver chip through the first overvoltage protection unit when an overvoltage abnormality occurs at the second low-voltage output port. This improves the local response capability of the bidirectional switch module to abnormalities at the second low-voltage output port, reduces the dependence on the main control judgment of the DCDC module, and enhances the timeliness and safety of fault isolation actions.

[0010] Preferably, the disconnecting switch unit includes two back-to-back connected MOSFET groups, each MOSFET group including multiple MOSFETs arranged in parallel with the same blocking direction, wherein each MOSFET is connected in reverse series with the corresponding MOSFET in the other MOSFET group.

[0011] By adopting the above technical solutions, the disconnecting switch unit can share large currents when conducting, reduce the conduction loss and heat generation pressure of a single MOSFET, and block bidirectional current transmission between the first low-voltage output port and the second low-voltage output port when turning off, thereby improving the current carrying capacity, heat dissipation reliability and bidirectional isolation effect of the bidirectional disconnecting switch.

[0012] Preferably, the bidirectional switching module further includes a switching current acquisition unit, which is located on the current transmission path between the two MOS transistor groups, and the sampling signal output terminal of the switching current acquisition unit is connected to the current detection signal input terminal of the driver chip. The switch current acquisition unit includes multiple sampling resistors connected in parallel. These resistors are used to shunt and sample the current flowing through the isolating switch unit to generate a corresponding switch current acquisition signal.

[0013] By adopting the above technical solution, the driver chip can obtain the actual current change in the bidirectional switching module, thereby providing a detection basis for overcurrent judgment, current direction identification, and isolation execution status judgment. At the same time, the parallel connection of multiple sampling resistors can reduce the power consumption and heat generation of the sampling path and improve the stability of high current detection.

[0014] Preferably, the first overvoltage protection unit includes at least one first operational amplifier, at least one first voltage divider resistor, and at least one second voltage divider resistor. The first end of the first voltage divider resistor is connected to the second low-voltage output port, the second end of the first voltage divider resistor is connected to the first end of the second voltage divider resistor, the second end of the second voltage divider resistor is grounded, the common node between the second end of the first voltage divider resistor and the first end of the second voltage divider resistor is connected to the input terminal of the first operational amplifier, and the output terminal of the first operational amplifier is connected to the shutdown signal input terminal of the driver chip.

[0015] By adopting the above technical solution, the voltage of the second low-voltage output port can be divided and then input to the operational amplifier for judgment. When the voltage of the second low-voltage output port exceeds the set safety range, a shutdown signal is output to the driver chip, thereby realizing rapid detection and local protection of overvoltage abnormalities of the second low-voltage output port, and avoiding the abnormal voltage on the second low-voltage output port side from affecting the first low-voltage output port side and the DC-DC module.

[0016] Preferably, the DC-DC module includes a DC-DC main circuit unit, a DC-DC driver chip, and a main control chip. The power input terminal of the DC-DC main circuit unit is connected to a high-voltage DC power supply. After voltage conversion by the DC-DC main circuit unit, the power output terminal of the DC-DC main circuit unit is determined as the first low-voltage output port, thereby outputting low-voltage power for power supply. The data communication terminal of the main control chip is connected to the data transmission port for outputting switch control signals and receiving status signals. The control signal output terminal of the main control chip is connected to the control signal input terminal of the DC-DC driver chip, and the drive signal output terminal of the DC-DC driver chip is connected to the drive signal input terminal of the DC-DC main circuit unit.

[0017] By adopting the above technical solution, the high-voltage DC power supply can be converted into a low-voltage power supply at the first low-voltage output port through the DCDC main circuit unit. The main control chip drives and controls the DCDC main circuit unit through the DCDC driver chip. At the same time, the main control chip interacts with the bidirectional switch module through the data transmission port, thereby realizing the coordination of DCDC output control, bidirectional switch control and status feedback processing, and improving the centralization and reliability of the vehicle's low-voltage power supply control.

[0018] Preferably, the DCDC module further includes a second overvoltage protection unit, which includes a second operational amplifier. The input terminal of the second operational amplifier is connected to the first low-voltage output port, and the output terminal of the second operational amplifier is connected to the overvoltage shutdown signal input terminal of the DCDC driver chip.

[0019] By adopting the above technical solution, when an overvoltage abnormality occurs at the first low-voltage output port, the DC-DC driver chip can be directly triggered to perform shutdown protection, thereby realizing hardware-level fast protection on the DC-DC output side and preventing the overvoltage at the first low-voltage output port from continuing to be transmitted to the low-voltage main power supply equipment or bidirectional switch module.

[0020] Preferably, the DC-DC module further includes a DC-DC voltage acquisition unit and a DC-DC current acquisition unit. The signal input terminals of the DC-DC voltage acquisition unit and the DC-DC current acquisition unit are both connected to the first low-voltage output port. The signal output terminal of the DC-DC voltage acquisition unit is connected to the voltage signal input terminal of the main control chip, and the signal output terminal of the DC-DC current acquisition unit is connected to the current signal input terminal of the main control chip.

[0021] By adopting the above technical solution, the main control chip can obtain the output voltage and output current of the first low-voltage output port in real time, and determine whether there are abnormal states such as overvoltage, undervoltage, overcurrent or short circuit at the first low-voltage output port, thereby providing continuous detection data support for DCDC output shutdown, bidirectional switch disconnection and fault status reporting.

[0022] Preferably, the main control chip is equipped with a CAN communication port, which is connected to the CAN module to output corresponding operating status information and / or receive external control commands.

[0023] By adopting the above technical solution, the main control chip can send the operating status information, abnormal power supply status information, and isolation execution status information of the DC-DC module and the bidirectional switch module to the vehicle control system, and at the same time receive external control commands, thereby realizing data interaction between the on-board DC-DC bidirectional isolation switch circuit and the vehicle control system, which facilitates the vehicle to perform fault warning, fault recording, and safety degradation control.

[0024] A control method for an on-board DC-DC bidirectional disconnect switch circuit, applied to an on-board DC-DC bidirectional disconnect switch circuit, the control method includes: The system acquires the output voltage and output current parameters corresponding to the first low-voltage output port. When the output voltage parameter of the first low-voltage output port exceeds a preset overvoltage threshold, the system controls the DC-DC module to shut down the output and controls the bidirectional switch module to disconnect the connection between the first low-voltage output port and the second low-voltage output port. When the output current parameter of the first low-voltage output port exceeds a preset overcurrent threshold, or when the output voltage parameter of the first low-voltage output port is lower than a preset undervoltage threshold, the system controls the DC-DC module to shut down the output and controls the bidirectional switch module to disconnect the connection between the first low-voltage output port and the second low-voltage output port. Obtain the second power supply status parameter corresponding to the second low-voltage output port. When the second power supply status parameter of the second low-voltage output port meets the preset abnormal conditions, control the bidirectional switch module to automatically disconnect the connection between the first low-voltage output port and the second low-voltage output port. The switching current parameters and current direction parameters flowing through the bidirectional switching module are obtained. When the switching current parameters exceed the preset switching current threshold, the bidirectional switching module is controlled to disconnect the connection between the first low-voltage output port and the second low-voltage output port based on the current direction parameters. After either the first low-voltage output port or the second low-voltage output port is isolated by a fault, low-voltage power is supplied to the backup low-voltage power supply equipment through the low-voltage battery. When the vehicle's low-voltage system enters the power-down state, a disconnect command is sent to the bidirectional switch module, and the electrical detection results of the first low-voltage output port, the second low-voltage output port, and the bidirectional switch module are obtained. Based on the electrical detection results, it is determined whether the bidirectional switch module can disconnect normally.

[0025] By adopting the above technical solution, the system can promptly isolate the first low-voltage output port and the second low-voltage output port according to the location of the fault and the abnormal current state; at the same time, after the fault is isolated, the low-voltage battery maintains the backup low-voltage power supply equipment, and performs a self-test to disconnect the bidirectional switch module when the vehicle is powered off, thereby improving the availability, detectability and functional safety and reliability of the bidirectional disconnect switch in actual fault scenarios.

[0026] In summary, this application includes at least one of the following beneficial technical effects: This application establishes a low-voltage power supply safety architecture of "main power supply detection and judgment + bidirectional isolation execution + backup power supply maintenance" by setting a bidirectional switch module between the first low-voltage output port of the DC-DC module and the second low-voltage output port where the low-voltage battery is located, and enabling the DC-DC module and the bidirectional switch module to exchange status signals and switch control signals through a data transmission interface. Specifically, the DC-DC module outputs a first low-voltage power supply to the low-voltage main power supply equipment, and can detect abnormal power supply states such as overvoltage, undervoltage, overcurrent, and short circuit at the first low-voltage output port through its own signal acquisition terminal. The bidirectional switch module is set between the first and second low-voltage output ports to control whether the DC-DC side and the low-voltage battery side are connected. When the DC-DC module detects an abnormality on its own output side, or judges that the second low-voltage output port is abnormal based on the status signal fed back by the bidirectional switch module, the DC-DC module can actively control the bidirectional switch module to disconnect; at the same time, when the bidirectional switch module itself detects an abnormality in the second low-voltage output port, it can also automatically disconnect without relying on the main control judgment of the DC-DC module. This dual-path isolation control method does not simply shut down the system directly in the event of a DCDC failure. Instead, it promptly disconnects the electrical connection between the first and second low-voltage output ports when an abnormality occurs on the DCDC side, the backup side, or the connection path between the two. This prevents short circuits, overvoltages, or abnormal backflow from the faulty side to the healthy side. While retaining the cost advantages of redundant power distribution between a single DCDC and a low-voltage battery, it improves the fault isolation capability and power supply continuity between the two low-voltage outputs. This allows the low-voltage battery to continue supplying power to the backup low-voltage power supply equipment after a fault occurs, preventing critical low-voltage equipment such as brakes, steering, and intelligent driving controllers from simultaneously losing power due to DCDC malfunctions. This enhances the functional safety and reliability of the vehicle's low-voltage power supply system and better meets the requirements for fault isolation, fault control, and continuous power supply to critical loads under high functional safety levels. Attached Figure Description

[0027] Figure 1 This is a flowchart of a vehicle-mounted DC-DC bidirectional isolation switch circuit according to one embodiment of this application; Figure 2 This is a partial circuit structure diagram of existing technology. Figure 1 ; Figure 3 This is a partial circuit structure diagram of existing technology. Figure 2 ; Figure 4 This is a partial circuit structure diagram of a vehicle-mounted DC-DC bidirectional isolation switch circuit according to one embodiment of this application; Figure 5 This is a flowchart of a vehicle-mounted DC-DC bidirectional disconnector method according to one embodiment of this application. Detailed Implementation

[0028] The present application will be further described in detail below with reference to the accompanying drawings.

[0029] In one embodiment, such as Figure 1 and Figure 4 As shown, this application discloses an on-board DC-DC bidirectional isolation switch circuit, including a DC-DC module, a bidirectional switch module, a data transmission interface, a low-voltage main power supply device, a backup low-voltage power supply device, and a low-voltage battery; The low-voltage output port of the DCDC module forms the first low-voltage output port, which is connected to the power input terminal of the low-voltage main power supply equipment and the first power connection terminal of the bidirectional switch module. The second power connection terminal of the bidirectional switch module forms a second low-voltage output port, which is connected to the power input terminal of the backup low-voltage power supply equipment and the power input terminal of the low-voltage battery, respectively. The DC-DC module and the bidirectional switch module transmit corresponding status signals and switch control signals through a data transmission interface. The switch control signal is used to control the bidirectional switch module to turn on or off between the first low-voltage output port and the second low-voltage output port. When the signal acquisition terminal of the DC-DC module detects an abnormal power supply state at the first low-voltage output port or determines an abnormal power supply state at the second low-voltage output port based on the status signal, the DC-DC module controls the bidirectional switch module to disconnect to isolate the first low-voltage output port and the second low-voltage output port. When the signal acquisition terminal of the bidirectional switch module detects an abnormal power supply state at the second low-voltage output port, the bidirectional switch module automatically disconnects to isolate the first low-voltage output port and the second low-voltage output port. After either the first low-voltage output port or the second low-voltage output port is fault-isolated, the low-voltage battery is used to provide low-voltage power to the backup low-voltage power supply equipment.

[0030] In one specific embodiment, an on-board DC-DC bidirectional isolation switch circuit is applied to the low-voltage power supply system of a new energy vehicle. It establishes a controllable connection between the main low-voltage power supply path formed by the high-voltage power battery after DC-DC conversion and the backup low-voltage power supply path where the low-voltage battery is located. This circuit may include a DC-DC module, a bidirectional switch module, a data transmission interface, a low-voltage main power supply device, a backup low-voltage power supply device, and a low-voltage battery. The DC-DC module, as the main power conversion part, receives electrical energy from the vehicle's high-voltage DC power supply on its input side and converts this high-voltage DC power into low-voltage DC power suitable for the vehicle's low-voltage system. The low-voltage output side of the DC-DC module serves as the main low-voltage output node. This main low-voltage output node is connected to the low-voltage main power supply device on one hand to provide operating power to conventional low-voltage loads or main power supply side loads, and on the other hand, it is connected to one side of the bidirectional switch module, allowing the low-voltage power output by the DC-DC module to be transmitted to another low-voltage power supply branch when the bidirectional switch module is in the ON state. Therefore, the DC-DC module not only undertakes voltage conversion and main power supply output functions, but also serves as the power supply status detection and control management part of the first low-voltage output port. It is used to collect the voltage, current or other power supply status on its own output side, and participate in subsequent isolation control when an abnormality is detected.

[0031] A bidirectional switch module is positioned between the main low-voltage output node of the DC-DC module and the low-voltage node on the low-voltage battery side. Its first side connects to the first low-voltage output port formed by the DC-DC module's output, and its second side forms the second low-voltage output port. The second low-voltage output port can simultaneously connect to backup low-voltage power supply equipment and the low-voltage battery, ensuring that the low-voltage battery is in a state of cooperation with the low-voltage power supply network when the DC-DC module is operating normally, and continues to supply power to the backup low-voltage power supply equipment after a fault occurs in the main low-voltage output branch. The bidirectional switch module does not simply function as a regular wiring switch, but rather as an active isolation actuator between the first and second low-voltage output ports. Under normal system conditions, it remains conductive, establishing a connection between the low-voltage output of the DC-DC module and the low-voltage battery power supply network, thus achieving coordination between the main and backup power supplies. In the event of overvoltage, undervoltage, overcurrent, short circuit, or abnormal backflow faults on either side, it can disconnect the current transmission path between the two sides, preventing the faulty side from dragging or impacting the normal side, thereby avoiding the spread of low-voltage power supply faults between the two output ports.

[0032] The data transmission interface establishes a control and status feedback channel between the DC-DC module and the bidirectional switch module. Through this interface, the DC-DC module can send switching control signals to the bidirectional switch module to control its on / off state. The bidirectional switch module can also send status signals back to the DC-DC module related to its own operating status, the power supply status of the second low-voltage output port, or the status of the isolation path. These status signals can characterize whether there is abnormal voltage at the second low-voltage output port, whether the bidirectional switch module is in a conducting or disconnected state, whether there is abnormal current in the isolation path, and whether there is reverse current flow. Through this signal interaction, the DC-DC module does not only perform unilateral protection based on its own output status, but can also combine the information fed back by the bidirectional switch module to comprehensively judge the power supply relationship between the first and second low-voltage output ports, thereby improving the accuracy of fault location identification and isolation control.

[0033] When the vehicle's low-voltage system is operating normally, the DC-DC module outputs low-voltage power to the first low-voltage output port. The main low-voltage power supply equipment obtains power from this first low-voltage output port. The bidirectional switch module remains on, establishing a current-transferable connection between the first and second low-voltage output ports. At this time, the backup low-voltage power supply equipment and low-voltage battery on the second low-voltage output port side are in a power supply state linked to the main low-voltage output branch, and the entire vehicle's low-voltage system is maintained by the DC-DC module as the main power source. When the DC-DC module's signal acquisition end detects an abnormal power supply status at the first low-voltage output port—for example, the output voltage is higher than the safe range, lower than the operating range, the output current is too large, or a suspected short circuit occurs—the DC-DC module can determine that there is a risk of failure on the main power supply side and send a disconnect control signal to the bidirectional switch module through the data transmission interface. This causes the bidirectional switch module to disconnect the connection between the first and second low-voltage output ports. Thus, even if a fault occurs on the DC-DC module's output side, it will not continue to affect the low-voltage battery side or the backup low-voltage power supply equipment side. The low-voltage battery can continue to provide low-voltage power to the backup low-voltage power supply equipment after isolation.

[0034] When an anomaly occurs at the second low-voltage output port, the system can achieve isolation control through two paths. Firstly, the bidirectional switch module can feed back the detected status of the second low-voltage output port to the DC-DC module via a data transmission interface. The DC-DC module then determines whether an abnormal power supply state exists at the second low-voltage output port based on this status signal and controls the bidirectional switch module to disconnect when an anomaly is confirmed. Secondly, the bidirectional switch module itself can directly detect the power supply status of the second low-voltage output port through its signal acquisition terminal. When it detects overvoltage, overcurrent, or other anomalies that meet local protection conditions at the second low-voltage output port, it can automatically disconnect without waiting for control commands from the DC-DC module. These two isolation triggering paths form a safety mechanism combining system-level control and local protection, preventing the timely disconnection of the bidirectional switch module from being affected by DC-DC module judgment delays, communication anomalies, or main control failures.

[0035] The low-voltage main power supply equipment primarily receives the first low-voltage power output from the DC-DC module, which powers controllers, actuators, or other low-voltage loads in the vehicle that are powered by the main low-voltage power supply path. The backup low-voltage power supply equipment is connected to the second low-voltage output port side. It continues to provide power in case of an anomaly on the main low-voltage output side or isolation of the main power supply path, ensuring that low-voltage equipment in the vehicle with high power continuity requirements does not immediately lose power due to a DC-DC side failure. The low-voltage battery is connected to the second low-voltage output port side, acting as a backup power storage component. When the connection between the first and second low-voltage output ports is severed, it can release energy to the backup low-voltage power supply equipment, thus maintaining the operation of the backup power supply branch. Through the cooperation of the low-voltage battery and the bidirectional switching module, the system can retain power supply capability on the other side in case of DC-DC module anomaly, short circuit on the main power supply side, or abnormal voltage at the first low-voltage output port, ensuring that the vehicle still has a power supply foundation for safe degradation, parking, or short-term maintenance of critical functions.

[0036] As can be seen from the above connections, the circuit's operating logic uses the DC-DC module as the main power supply and judgment unit, the bidirectional switch module as the isolation execution unit between the two low-voltage outputs, the data transmission interface as the control and status interaction channel, and the low-voltage battery as a backup power source. When an abnormal power supply state occurs on either the first or second low-voltage output port, the system can electrically isolate the two low-voltage outputs by controlling the DC-DC module to disconnect or by automatically disconnecting the bidirectional switch module locally, preventing the fault voltage or abnormal current from continuing to propagate to the healthy branch. After fault isolation is completed, the low-voltage battery can still support the operation of the backup low-voltage power supply equipment. This structure improves the fault isolation capability, power supply continuity, and functional safety and reliability of a single DC-DC and low-voltage battery redundant power distribution system without increasing the cost of dual DC-DC redundant power supply.

[0037] Furthermore, the bidirectional switch module includes a driver chip, an isolating switch unit, and a first overvoltage protection unit. The control signal input terminal of the driver chip is connected to the data transmission interface to acquire the corresponding switch control signal. The drive signal output terminal of the driver chip is connected to the controlled terminal of the isolating switch unit. The data communication terminal of the driver chip is connected to the data transmission interface to send the corresponding status signal. The first conducting terminal of the isolating switch unit is connected to the first low-voltage output port, and the second conducting terminal of the isolating switch unit is connected to the second low-voltage output port. The signal input terminal of the first overvoltage protection unit is connected to the second low-voltage output port, and the signal output terminal of the first overvoltage protection unit is connected to the turn-off signal input terminal of the driver chip.

[0038] Furthermore, the disconnecting switch unit includes two back-to-back connected MOSFET groups. Each MOSFET group includes multiple MOSFETs connected in parallel with the same blocking direction. Each MOSFET is connected in reverse series with a corresponding MOSFET in the other MOSFET group.

[0039] Furthermore, the bidirectional switching module also includes a switching current acquisition unit, which is located on the current transmission path between the two MOSFET groups. The sampling signal output terminal of the switching current acquisition unit is connected to the current detection signal input terminal of the driver chip. The switch current acquisition unit includes multiple sampling resistors connected in parallel. These resistors are used to shunt and sample the current flowing through the isolating switch unit to generate a corresponding switch current acquisition signal.

[0040] Furthermore, the first overvoltage protection unit includes at least one first operational amplifier, at least one first voltage divider resistor, and at least one second voltage divider resistor. The first end of the first voltage divider resistor is connected to the second low-voltage output port, the second end of the first voltage divider resistor is connected to the first end of the second voltage divider resistor, the second end of the second voltage divider resistor is grounded, the common node between the second end of the first voltage divider resistor and the first end of the second voltage divider resistor is connected to the input terminal of the first operational amplifier, and the output terminal of the first operational amplifier is connected to the shutdown signal input terminal of the driver chip.

[0041] In one specific embodiment, the bidirectional switch module can serve as an active isolation execution part between the first low-voltage output port and the second low-voltage output port. Its main function is to establish a current transmission path when both low-voltage outputs are in a normal state, and to disconnect the electrical connection between the two sides when an abnormal power supply risk occurs on either side. The bidirectional switch module may include a driver chip, an isolating switch unit, a first overvoltage protection unit, and a switch current acquisition unit. The driver chip, as the control and drive core within the bidirectional switch module, interacts with the DC-DC module via a data transmission interface. It can receive switch control signals from the DC-DC module and determine whether the isolating switch unit remains on or is turned off based on these signals. Simultaneously, the driver chip can also feed back the operating status, fault trigger status, current detection results, or current direction judgment results of the bidirectional switch module to the DC-DC module via the data transmission interface, enabling the DC-DC module to understand the actual operating conditions on the second low-voltage output port side and in the isolation path. Therefore, the driver chip not only undertakes the gate driving function of the power switch but also the status feedback and fault coordination between the bidirectional switch module and the DC-DC module.

[0042] The isolating switch unit connects between the first low-voltage output port and the second low-voltage output port. It is the power component in the bidirectional switching module that actually carries low-voltage current and performs switching operations. One side of the isolating switch unit is connected to the first low-voltage output port formed by the DC-DC module, and the other side is connected to the second low-voltage output port where the low-voltage battery and backup low-voltage power supply equipment are located. When the driver chip outputs a conduction signal, the isolating switch unit establishes a current path between the two sides, allowing the low-voltage current output by the DC-DC module to be transmitted to the second low-voltage output port side. When the driver chip outputs a turn-off signal, the isolating switch unit cuts off the current path between the first and second low-voltage output ports, electrically isolating the power supply networks on both sides, thereby preventing fault voltage, short-circuit current, or reverse backflow current from the fault side to the normal side.

[0043] To accommodate the potential bidirectional current flow in low-voltage vehicle systems, the disconnecting switch unit can employ two MOSFET groups connected back-to-back. Each MOSFET group can contain multiple MOSFETs connected in parallel, with all MOSFETs within the same group sharing the same blocking direction to collectively handle the load current during the on-state. The two MOSFET groups are configured in opposite directions, with the MOSFETs in one group connected in reverse series with their corresponding counterparts in the other group. This structure overcomes the unidirectional leakage problem caused by the body diode within a single MOSFET, enabling the disconnecting switch unit to simultaneously block current flowing from the first low-voltage output port to the second low-voltage output port and vice versa when turned off. The parallel connection of multiple MOSFETs also reduces the on-resistance and heat generation of individual MOSFETs, improving the load-bearing capacity and thermal stability of the bidirectional switching module in high-current, low-voltage power supply scenarios.

[0044] The switching current acquisition unit can be positioned on the current transmission path between two MOSFET groups to detect the actual current flowing through the isolating switch unit. Since this location is in the isolation path between the first and second low-voltage output ports, the current it acquires can reflect whether there is normal supply current, abnormal overcurrent, or reverse backflow current between the two low-voltage outputs. The sampling result from the switching current acquisition unit can be input to the driver chip, which obtains the magnitude of the isolation path current based on the sampling signal and determines the current flow direction by combining it with the detection circuit or the direction judgment logic inside the driver chip. Thus, when a short circuit on the second low-voltage output port side causes abnormal discharge from the low-voltage battery towards the first low-voltage output port, or when a fault on the first low-voltage output port side causes abnormal current output from the DCDC side towards the second low-voltage output port, the system can identify these events through this current detection path and provide a basis for the shutdown control of the bidirectional switching module.

[0045] In a specific circuit implementation, the switching current acquisition unit can include multiple sampling resistors connected in parallel. These multiple sampling resistors are connected together in the current detection path of the isolating switch unit, distributing the current flowing through the isolating switch unit across multiple sampling resistors, thereby reducing the power consumption and temperature rise borne by a single sampling resistor. The voltage drop across the sampling resistors can serve as the switching current acquisition signal. The amplitude of this signal is related to the magnitude of the current flowing through the isolating switch unit, and the driver chip can determine whether the current in the isolation path exceeds a preset safety range based on this voltage drop signal. Using multiple sampling resistors in parallel not only improves the detection reliability in high-current scenarios but also reduces the additional voltage drop generated by the sampling path on the main power supply circuit, minimizing the impact on low-voltage power supply efficiency.

[0046] The first overvoltage protection unit is used to locally detect the voltage on the second low-voltage output port side and directly trigger the bidirectional switch module to perform protection actions when an overvoltage abnormality occurs at the second low-voltage output port. The detection side of the first overvoltage protection unit is connected to the second low-voltage output port. Since the second low-voltage output port is connected to the low-voltage battery and backup low-voltage power supply equipment, an abnormal voltage boost at this port may have a reverse impact on the DC-DC output side or cause an impact on the backup low-voltage equipment. Therefore, an independent local overvoltage protection path needs to be set up inside the bidirectional switch module. The first overvoltage protection unit can proportionally sample the voltage of the second low-voltage output port through the first voltage divider resistor and the second voltage divider resistor, so that the higher port voltage is converted into a detection voltage suitable for the input range of the operational amplifier. The sampling node formed between the first voltage divider resistor and the second voltage divider resistor is connected to the input terminal of the first operational amplifier. The first operational amplifier is used to compare the sampled voltage with the set reference voltage or threshold condition. When the sampling result shows that the voltage of the second low-voltage output port exceeds the allowable range, the first operational amplifier outputs a shutdown trigger signal to the driver chip.

[0047] By directly connecting the output of the first overvoltage protection unit to the shutdown signal input of the driver chip, the bidirectional switch module can form a fast protection link independent of the DC-DC module's main control judgment when an overvoltage occurs at the second low-voltage output port. In other words, when an abnormally high voltage occurs at the second low-voltage output port, even if the DC-DC module has not yet completed its status judgment or there is a delay in the data transmission interface, the first overvoltage protection unit can still use hardware detection results to cause the driver chip to shut down the isolating switch unit, thereby quickly disconnecting the connection between the second and first low-voltage output ports. This design enables the bidirectional switch module to have local fault response capabilities, improving the isolation speed and power supply safety of overvoltage faults at the second low-voltage output port.

[0048] When the above structure works together, the driver chip comprehensively controls the conduction and disconnection of the isolating switch unit based on the switching control signal issued by the DC-DC module, the local overvoltage protection signal, and the switching current acquisition signal. Under normal power supply conditions, the driver chip controls the back-to-back MOSFET group to conduct, forming a controlled connection between the first low-voltage output port and the second low-voltage output port. When the first overvoltage protection unit detects an abnormal voltage at the second low-voltage output port, or the switching current acquisition unit detects an abnormal current in the isolation path, the driver chip controls the isolating switch unit to disconnect and can feed back the relevant status to the DC-DC module through the data transmission interface. Through this structure combining voltage detection, current sampling, drive control, and status feedback, the bidirectional switch module can achieve bidirectional current carrying, bidirectional fault isolation, local rapid protection, and operating status reporting in the vehicle low-voltage redundant power distribution system, thereby improving the isolation reliability between the first and second low-voltage output ports.

[0049] Furthermore, the DC-DC module includes a DC-DC main circuit unit, a DC-DC driver chip, and a main control chip. The power input terminal of the DC-DC main circuit unit is connected to a high-voltage DC power supply. After voltage conversion by the DC-DC main circuit unit, the power output terminal of the DC-DC main circuit unit is determined as the first low-voltage output port, thereby outputting low-voltage power for power supply. The data communication terminal of the main control chip is connected to the data transmission port for outputting switch control signals and receiving status signals. The control signal output terminal of the main control chip is connected to the control signal input terminal of the DC-DC driver chip, and the drive signal output terminal of the DC-DC driver chip is connected to the drive signal input terminal of the DC-DC main circuit unit.

[0050] Furthermore, the DCDC module also includes a second overvoltage protection unit, which includes a second operational amplifier. The input terminal of the second operational amplifier is connected to the first low-voltage output port, and the output terminal of the second operational amplifier is connected to the overvoltage shutdown signal input terminal of the DCDC driver chip.

[0051] Furthermore, the DC-DC module also includes a DC-DC voltage acquisition unit and a DC-DC current acquisition unit. The signal input terminals of both the DC-DC voltage acquisition unit and the DC-DC current acquisition unit are connected to the first low-voltage output port. The signal output terminal of the DC-DC voltage acquisition unit is connected to the voltage signal input terminal of the main control chip, and the signal output terminal of the DC-DC current acquisition unit is connected to the current signal input terminal of the main control chip.

[0052] Furthermore, the main control chip is equipped with a CAN communication port, which is connected to the CAN module to output corresponding operating status information and / or receive external control commands.

[0053] In one specific implementation, the DC-DC module can serve as the main power conversion and safety control component in an on-board low-voltage power supply system. It receives electrical energy from the vehicle's high-voltage DC power supply and converts this high-voltage DC into low-voltage DC usable by the vehicle's low-voltage system. The DC-DC module may include a DC-DC main circuit unit, a DC-DC driver chip, a main control chip, a second overvoltage protection unit, a DC-DC voltage acquisition unit, a DC-DC current acquisition unit, and a CAN module. The DC-DC main circuit unit, as the power circuit that actually performs the power conversion, has its power input side connected to a high-voltage DC power source, such as the DC bus power output from the vehicle's power battery pack via a high-voltage power distribution system. Its power output side forms a first low-voltage output port, used to provide low-voltage operating power to the low-voltage main power supply equipment, and forms a controllable connection with the low-voltage battery and backup low-voltage power supply equipment on the second low-voltage output port side through a bidirectional switching module. Thus, the DC-DC main circuit unit undertakes the high-voltage to low-voltage energy conversion function and is the main power source for the vehicle's low-voltage system under normal operating conditions.

[0054] The DC-DC driver chip is positioned between the main control chip and the DC-DC main circuit unit. It converts the control signals output by the main control chip into drive signals suitable for driving the power devices in the DC-DC main circuit unit. Since the DC-DC main circuit unit typically includes power devices such as switching transistors, transformers, inductors, and capacitors, the logic levels output by the main control chip alone are insufficient to directly meet the drive voltage, drive current, and timing requirements of the power switching devices. Therefore, by using the DC-DC driver chip to amplify, isolate, or time-shape the control signals, the DC-DC main circuit unit can perform energy conversion according to a set switching frequency, duty cycle, or operating mode. The control signal output side of the main control chip cooperates with the control input side of the DC-DC driver chip, and the drive output side of the DC-DC driver chip is then connected to the drive side of the DC-DC main circuit unit, thus forming a control link where the main control chip performs strategy control, the driver chip executes power drive, and the DC-DC main circuit unit completes voltage conversion.

[0055] The main control chip serves as the control core of the DC-DC module. It not only controls the start / stop and output status of the DC-DC main circuit unit but also interacts with the bidirectional switching module. The main control chip's data communication side connects to the bidirectional switching module via a data transmission interface to send switching control signals and receive status signals from the bidirectional switching module. These status signals can include information such as the on / off status of the bidirectional switching module, the abnormal status of the second low-voltage output port, and the current status or direction of the isolation path. Upon receiving this status information, the main control chip, combined with the voltage and current detection results of the first low-voltage output port, determines whether the current fault is more likely to occur on the DC-DC output side, the low-voltage battery side, or in the isolation path between the two. Based on this, it controls the DC-DC module to shut down its output or controls the bidirectional switching module to open. In this way, the main control chip no longer only protects the DC-DC module itself but also acts as a collaborative control node in the low-voltage power supply system, participating in fault isolation and safe power supply management between the two low-voltage outputs.

[0056] The second overvoltage protection unit serves as a hardware-level fast protection path within the DCDC module, detecting the output voltage of the first low-voltage output port. This unit may include a second operational amplifier. The input side of the second operational amplifier receives a detection signal related to the voltage of the first low-voltage output port, and the output side is connected to the overvoltage shutdown control side of the DCDC driver chip. When the voltage of the first low-voltage output port rises to the set overvoltage protection range due to DCDC control abnormalities, load surges, feedback anomalies, or power device failures, the second operational amplifier outputs an overvoltage shutdown signal based on a comparison between the input voltage and a preset reference condition. This causes the DCDC driver chip to stop outputting effective drive to the DCDC main circuit unit, thereby quickly stopping the DCDC main circuit unit from continuing to output abnormal voltage to the first low-voltage output port. This protection path primarily addresses the need for rapid shutdown when significant overvoltage occurs at the first low-voltage output port. Its response link is short and does not rely entirely on the software judgment of the main control chip, thus improving the protection speed of the DCDC output side under extreme overvoltage scenarios.

[0057] The DC-DC voltage acquisition unit and DC-DC current acquisition unit serve as continuous status detection components for the first low-voltage output port. The detection side of the DC-DC voltage acquisition unit is connected to the first low-voltage output port, converting the actual output voltage into a voltage detection signal recognizable by the main control chip and transmitting it to the main control chip's voltage detection side. Similarly, the detection side of the DC-DC current acquisition unit is associated with the power supply path of the first low-voltage output port, acquiring current changes from the DC-DC output to the low-voltage main power supply equipment and the bidirectional switching module, and transmitting the corresponding current detection signal to the main control chip. The main control chip can determine whether the first low-voltage output port experiences overvoltage, undervoltage, output fluctuations, or returns to normal based on the voltage detection signal, and determine whether there is overcurrent, short circuit, or abnormal load based on the current detection signal. Compared to the second overvoltage protection unit, the DC-DC voltage acquisition unit and DC-DC current acquisition unit are not merely for hardware shutdown under extreme fault conditions, but rather for providing continuous status data to the main control chip, enabling the main control chip to perform fault identification, fault trend judgment, isolation strategy selection, and fault reporting.

[0058] In actual operation, when the DC-DC voltage acquisition unit detects that the output voltage of the first low-voltage output port exceeds the normal operating range, or the DC-DC current acquisition unit detects that the output current exceeds the set safety range, the main control chip can first determine whether the abnormality belongs to a DC-DC output-side fault. Based on the determination result, it controls the DC-DC driver chip to stop driving the DC-DC main circuit unit, and simultaneously sends a disconnection control signal to the bidirectional switch module through the data transmission interface, thereby cutting off the connection between the first low-voltage output port and the second low-voltage output port. If the main control chip receives feedback from the bidirectional switch module about an abnormality in the second low-voltage output port or an abnormality in the isolation path through the data transmission interface, the main control chip can also control the bidirectional switch module to perform a disconnection action based on the status signal, preventing the abnormal status on the second low-voltage output port side from affecting the DC-DC output side in reverse. Thus, the main control chip, detection unit, driver chip, and data transmission interface in the DC-DC module together form a system-level protection link from status acquisition and fault diagnosis to isolation control.

[0059] The CAN module serves as a communication interface between the DC-DC converter and the vehicle control system. After the CAN communication port on the main control chip is connected to the CAN module, it can send information such as the DC-DC converter's operating status, the voltage and current status of the first low-voltage output port, status information fed back from the bidirectional switch module, fault isolation results, and abnormal power supply status to the vehicle controller or other vehicle electronic control units. Simultaneously, the main control chip can also receive external control commands from the vehicle control system via the CAN module, such as start / stop control commands, fault reset commands, safety degradation commands, or power-down self-test commands. By configuring the CAN module, the DC-DC converter can be expanded from a standalone power converter into a communication node in the vehicle's low-voltage power supply safety management, enabling the vehicle control system to promptly grasp the fault status of the low-voltage power supply system and execute alarms, degradation, power limiting, parking, or other safety strategies based on the fault type.

[0060] When the above structures work together, the high-voltage DC power supply is first converted by the DCDC main circuit unit to low-voltage power supply to the first low-voltage output port. The main control chip controls the working state of the DCDC main circuit unit through the DCDC driver chip, and continuously monitors the output status of the first low-voltage output port through the DCDC voltage acquisition unit and the DCDC current acquisition unit. When a severe overvoltage occurs at the first low-voltage output port, the second overvoltage protection unit can directly act on the DCDC driver chip, causing the DCDC main circuit unit to quickly stop outputting. When the main control chip detects abnormalities such as overvoltage, undervoltage, overcurrent, or short circuit, it can control the DCDC module to shut down its output and control the bidirectional switch module to disconnect based on the acquisition results and the status signal fed back by the bidirectional switch module. Through this structure that combines hardware overvoltage protection, software sampling and judgment, drive control, bidirectional switch coordination, and CAN communication reporting, the DCDC module can not only complete the main low-voltage power supply output, but also participate in fault isolation and vehicle functional safety management in abnormal power supply scenarios, thereby improving the reliability and safety controllability of the vehicle low-voltage power supply system.

[0061] like Figure 5 As shown, a control method for an on-board DC-DC bidirectional disconnect switch circuit is applied to an on-board DC-DC bidirectional disconnect switch circuit. The control method includes: S10. Obtain the output voltage and output current parameters corresponding to the first low-voltage output port. When the output voltage parameter of the first low-voltage output port exceeds the preset overvoltage threshold, control the DCDC module to turn off the output and control the bidirectional switch module to disconnect the connection between the first low-voltage output port and the second low-voltage output port. When the output current parameter of the first low-voltage output port exceeds the preset overcurrent threshold, or when the output voltage parameter of the first low-voltage output port is lower than the preset undervoltage threshold, control the DCDC module to turn off the output and control the bidirectional switch module to disconnect the connection between the first low-voltage output port and the second low-voltage output port. S20. Obtain the second power supply status parameter corresponding to the second low-voltage output port. When the second power supply status parameter of the second low-voltage output port meets the preset abnormal conditions, control the bidirectional switch module to automatically disconnect the connection between the first low-voltage output port and the second low-voltage output port. S30. Obtain the switching current parameters and current direction parameters flowing through the bidirectional switch module. When the switching current parameters exceed the preset switching current threshold, control the bidirectional switch module to disconnect the connection between the first low-voltage output port and the second low-voltage output port based on the current direction parameters. S40. After either the first low-voltage output port or the second low-voltage output port is fault-isolated, low-voltage power is supplied to the backup low-voltage power supply equipment through the low-voltage battery. S50. When the vehicle's low-voltage system enters the power-off state, a disconnect command is sent to the bidirectional switch module, and the electrical detection results of the first low-voltage output port, the second low-voltage output port, and the bidirectional switch module are obtained. Based on the electrical detection results, it is determined whether the bidirectional switch module can be disconnected normally.

[0062] In this embodiment, the control method of the on-board DC-DC bidirectional isolation switch circuit refers to a control process used to coordinate the power supply status between the DC-DC module, the bidirectional switch module, the low-voltage battery, and the low-voltage load. Its purpose is to ensure that the vehicle's low-voltage system receives primary low-voltage power from the DC-DC module under normal operating conditions, and to promptly identify faults, isolate power supplies, and maintain backup power when abnormalities occur on the DC-DC output side, the low-voltage battery side, or the connection path between the two outputs. The on-board DC-DC bidirectional isolation switch circuit is a low-voltage power supply safety circuit installed between the vehicle's high-voltage power supply and the low-voltage electrical system. It includes not only the DC-DC module for converting high-voltage DC to low-voltage DC, but also a bidirectional switch module located between the two low-voltage outputs, enabling the main low-voltage power supply path and the backup low-voltage power supply path to be connected or disconnected according to the fault state. The DC-DC module can be understood as the main power conversion and control unit in the vehicle's low-voltage power supply system. It converts the DC power from the high-voltage power battery side into a low-voltage power supply usable by the vehicle's low-voltage equipment and uses voltage and current detection results to determine whether there is an abnormality at the first low-voltage output port. A bidirectional switch module can be understood as an electronic isolation component arranged between the first low-voltage output port and the second low-voltage output port. Under normal conditions, it allows the low-voltage power supply networks on both sides to be connected. When an abnormality is detected or a disconnection control is received, it cuts off the current path between the two sides, thereby preventing the fault voltage or abnormal current from continuing to be transmitted to the other side.

[0063] The first low-voltage output port refers to the main low-voltage output node formed after the DC-DC module completes voltage conversion. This node is typically used to supply power to the low-voltage main power supply equipment and serves as the main power supply connection point between the DC-DC module and the bidirectional switching module. Output voltage parameters are detection data reflecting the magnitude and change state of the voltage at the first low-voltage output port. These can be obtained by the DC-DC voltage acquisition unit through voltage division, filtering, analog-to-digital conversion, etc. The main control chip can use this parameter to determine whether the DC-DC output is within the normal voltage range. Output current parameters are detection data reflecting the magnitude of the current output from the first low-voltage output port to the external load or bidirectional switching module. These can be obtained by a sampling resistor, Hall current sensor, or current detection amplifier circuit. The main control chip can use this parameter to determine whether there is an overload, short circuit, or abnormal discharge on the DC-DC output side. The preset overvoltage threshold is the highest permissible voltage boundary preset according to the safe operating range of the low-voltage system. When the output voltage parameter of the first low-voltage output port exceeds this boundary, it can be considered that there is an overvoltage risk on the DC-DC output side, requiring rapid shutdown of the DC-DC output and disconnection from the second low-voltage output port. The preset overcurrent threshold is the maximum allowable current value set based on the rated output capacity of the DCDC module, the wiring harness carrying capacity, the safe current of the switching devices, and the operating requirements of low-voltage loads. When the output current parameter exceeds this value, it can be determined that there may be a short circuit or severe overload in the main power supply path. The preset undervoltage threshold is used to determine whether the DCDC output is lower than the minimum allowable voltage boundary required for normal power supply. When the output voltage parameter is lower than this boundary, it may indicate that the DCDC module's output capacity is insufficient, the power supply path is abnormal, or there is a load-side failure. In this case, it is necessary to shut down the DCDC output and disconnect the bidirectional switching module to prevent the abnormal state from escalating further.

[0064] The second low-voltage output port refers to the low-voltage node formed by the bidirectional switching module near the low-voltage battery and backup low-voltage power supply equipment. This node can receive low-voltage power from the DC-DC side through the bidirectional switching module under normal conditions, or the low-voltage battery can continue to supply power to the backup low-voltage power supply equipment after fault isolation. The second power supply status parameter refers to the detection data used to characterize the operating status of the second low-voltage output port. This can include the voltage value of the second low-voltage output port, voltage change trend, overvoltage trigger state, undervoltage state, or other protection states related to the second low-voltage output port. The preset abnormal conditions refer to the judgment rules used to determine whether the second low-voltage output port has entered an unsafe power supply state. These can be set based on the allowable voltage range of the second low-voltage output port, the operating range of the low-voltage battery, the withstand voltage requirements of the backup low-voltage equipment, and the local protection strategy of the bidirectional switching module. For example, the second low-voltage output port voltage exceeding the local overvoltage threshold, falling below the minimum supply voltage, experiencing an abnormal voltage surge, or detecting abnormal energy transfer inconsistent with the normal power supply direction can all be considered as satisfying the preset abnormal conditions.

[0065] Switching current parameters refer to the current detection results flowing through the internal isolation path of the bidirectional switching module. The detected object is not simply the current at the first or second low-voltage output port, but rather the actual current transmitted between the first and second low-voltage output ports through the bidirectional switching module. This parameter can be obtained through a sampling resistor, sampling amplifier, or current detection chip set on the current path of the isolating switch unit, and is used to determine whether there is abnormal overcurrent, short-circuit current, or continuous backflow current between the two low-voltage outputs. Current direction parameters are data characterizing the flow direction of the switching current in the bidirectional switching module. They reflect whether the current flows from the first low-voltage output port to the second low-voltage output port, or vice versa. Using current direction parameters, the control system can further determine whether abnormal current is more likely to originate from the main power supply side of the DC-DC converter or the low-voltage battery and backup power supply side, thus providing a basis for disconnecting the bidirectional switching module, shutting down the DC-DC output, or reporting the fault type. The preset switching current threshold refers to the safe current limit set for the isolation path of the bidirectional switching module. It can be determined based on the current carrying capacity of the MOSFET, the power consumption of the sampling resistor, the wiring harness specifications, the fuse protection requirements, and the short-circuit protection strategy of the low-voltage system. When the switching current parameter exceeds this threshold, it indicates that there is an abnormal current transmission between the two low-voltage outputs that should not be continued, and the bidirectional switching module needs to be controlled to disconnect.

[0066] Fault isolation refers to the process of disconnecting the electrical connection between the faulty side and the healthy side by controlling the bidirectional switch module to disconnect after an abnormality occurs in the current transmission path of the first low-voltage output port, the second low-voltage output port, or the bidirectional switch module. This process does not simply shut down the entire low-voltage system, but rather aims to limit the fault to the side where the abnormality occurs, allowing the other side to maintain power supply capability. A low-voltage battery is a low-voltage energy storage component connected to the second low-voltage output port side. It can be a 12V battery or a battery used in other vehicle low-voltage systems, used to continue supplying power to the second low-voltage output port side after the DC-DC module stops outputting or the main power supply path is isolated. Backup low-voltage power supply equipment refers to low-voltage electrical equipment connected to the second low-voltage output port side that needs to maintain power supply when the main power supply is abnormal. It can include controllers, actuators, or other low-voltage loads that require continuous power supply related to vehicle safety. The vehicle low-voltage system refers to the electrical system in the vehicle powered by a low-voltage power source, including controllers, sensors, actuators, communication modules, low-voltage batteries, and related wiring harnesses and protection circuits. The power-down state refers to the state in which the vehicle's low-voltage system enters a state of shutdown, hibernation, or preparation to disconnect the operating power supply. In this state, the system load is relatively low, making it suitable for performing disconnection tests on the bidirectional switch module to confirm its reliable disconnection capability in real fault scenarios. The disconnection command refers to the control command sent by the DC-DC module, vehicle controller, or relevant main control unit to the bidirectional switch module, used to switch the bidirectional switch module from the on state to the off state. The electrical test result refers to the test results such as voltage, current, on state, off state, or residual current obtained during the power-down self-test or fault isolation process. It is used to determine whether the bidirectional switch module has disconnected the current transmission path between the two low-voltage outputs as instructed. In step S50, "electrical test result" should be consistently expressed as "electrical test result" in actual writing to avoid repetition and misunderstanding.

[0067] The corresponding working principle is as follows: During normal vehicle operation, the DC-DC module converts high-voltage DC power into low-voltage power at the first low-voltage output port and maintains a controlled connection with the second low-voltage output port through a bidirectional switch module, ensuring stable power supply to both the main low-voltage power supply equipment and the backup low-voltage power supply equipment. The control system continuously collects the voltage and current at the first low-voltage output port. When the first low-voltage output port experiences overvoltage, undervoltage, overcurrent, or short-circuit risks, it indicates that the main DC-DC power supply side may be unable to supply power safely. At this time, the system shuts down the DC-DC module output and disconnects the bidirectional switch module to prevent the abnormality at the first low-voltage output port from continuing to affect the second low-voltage output port side. Simultaneously, the bidirectional switch module also performs local power supply status detection at the second low-voltage output port. When an abnormality meeting the protection conditions occurs on the low-voltage battery side or the backup power supply side, the bidirectional switch module can directly disconnect the connections on both sides to prevent the abnormality at the second low-voltage output port side from being transmitted back to the DC-DC side. The system also detects the magnitude and direction of the current flowing through the bidirectional switch module. When a current exceeding the safe range appears in the isolation path, the source of the abnormal current can be determined by combining the current direction, and the bidirectional switch module can be controlled to disconnect. After isolation is completed, if the second low-voltage output port is still in a power-available state, the low-voltage battery continues to supply power to the backup low-voltage power supply equipment, providing a power foundation for the vehicle's critical low-voltage equipment to maintain operation. When the vehicle enters a power-down state, the system actively sends a disconnect command to the bidirectional switch module and confirms whether the switch is actually disconnected by detecting the voltage, current, and isolation path status of both ports. This allows for early detection of potential problems such as adhesion, breakdown, or inability to turn off the bidirectional switch module, ensuring that it can reliably perform isolation actions in subsequent real-world fault scenarios.

[0068] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A vehicle-mounted DC-DC bidirectional isolation switch circuit, characterized in that, Includes DC-DC module, bidirectional switch module, data transmission interface, low-voltage main power supply equipment, backup low-voltage power supply equipment and low-voltage battery; The low-voltage output port of the DC-DC module forms a first low-voltage output port, which is connected to the power input terminal of the low-voltage main power supply equipment and the first power connection terminal of the bidirectional switch module. The second power connection terminal of the bidirectional switch module forms a second low-voltage output port, which is connected to the power input terminal of the backup low-voltage power supply equipment and the power input terminal of the low-voltage battery, respectively. The DC-DC module and the bidirectional switch module transmit corresponding status signals and switch control signals through the data transmission interface. The switch control signal is used to control the bidirectional switch module to turn on or off between the first low-voltage output port and the second low-voltage output port. When the signal acquisition terminal of the DC-DC module detects an abnormal power supply state at the first low-voltage output port or determines an abnormal power supply state at the second low-voltage output port based on the status signal, the DC-DC module controls the bidirectional switch module to disconnect, thereby isolating the first low-voltage output port and the second low-voltage output port. When the signal acquisition terminal of the bidirectional switch module detects an abnormal power supply state at the second low-voltage output port, the bidirectional switch module automatically disconnects to isolate the first low-voltage output port and the second low-voltage output port. After either the first low-voltage output port or the second low-voltage output port is fault-isolated, the low-voltage battery is used to provide low-voltage power to the backup low-voltage power supply equipment.

2. The on-board DC-DC bidirectional isolation switch circuit according to claim 1, characterized in that, The bidirectional switch module includes a driver chip, an isolating switch unit, and a first overvoltage protection unit. The control signal input terminal of the driver chip is connected to the data transmission interface to acquire the corresponding switch control signal. The drive signal output terminal of the driver chip is connected to the controlled terminal of the isolating switch unit. The data communication terminal of the driver chip is connected to the data transmission interface to send the corresponding status signal. The first conducting terminal of the isolating switch unit is connected to the first low-voltage output port, and the second conducting terminal of the isolating switch unit is connected to the second low-voltage output port. The signal input terminal of the first overvoltage protection unit is connected to the second low-voltage output port, and the signal output terminal of the first overvoltage protection unit is connected to the turn-off signal input terminal of the driver chip.

3. The on-board DC-DC bidirectional isolation switch circuit according to claim 2, characterized in that, The disconnecting switch unit includes two back-to-back connected MOS transistor groups. Each MOS transistor group includes multiple MOS transistors arranged in parallel with the same blocking direction. Each MOS transistor is connected in reverse series with a corresponding MOS transistor in the other MOS transistor group.

4. The vehicle-mounted DC-DC bidirectional isolation switch circuit according to claim 3, characterized in that, The bidirectional switch module further includes a switch current acquisition unit, which is located on the current transmission path between the two MOS transistor groups. The sampling signal output terminal of the switch current acquisition unit is connected to the current detection signal input terminal of the driver chip. The switch current acquisition unit includes multiple sampling resistors connected in parallel. These multiple sampling resistors are used to shunt and sample the current flowing through the isolation switch unit to generate a corresponding switch current acquisition signal.

5. A vehicle-mounted DC-DC bidirectional isolation switch circuit according to claim 2, characterized in that, The first overvoltage protection unit includes at least one first operational amplifier, at least one first voltage divider resistor, and at least one second voltage divider resistor. The first end of the first voltage divider resistor is connected to the second low-voltage output port, the second end of the first voltage divider resistor is connected to the first end of the second voltage divider resistor, the second end of the second voltage divider resistor is grounded, the common node between the second end of the first voltage divider resistor and the first end of the second voltage divider resistor is connected to the input terminal of the first operational amplifier, and the output terminal of the first operational amplifier is connected to the shutdown signal input terminal of the driver chip.

6. The on-board DC-DC bidirectional isolation switch circuit according to claim 1, characterized in that, The DC-DC module includes a DC-DC main circuit unit, a DC-DC driver chip, and a main control chip. The power input terminal of the DC-DC main circuit unit is connected to a high-voltage DC power supply. After voltage conversion by the DC-DC main circuit unit, the power output terminal of the DC-DC main circuit unit is determined as the first low-voltage output port, thereby outputting low-voltage power for power supply. The data communication terminal of the main control chip is connected to the data transmission port for outputting switch control signals and receiving status signals. The control signal output terminal of the main control chip is connected to the control signal input terminal of the DC-DC driver chip, and the drive signal output terminal of the DC-DC driver chip is connected to the drive signal input terminal of the DC-DC main circuit unit.

7. A vehicle-mounted DC-DC bidirectional isolation switch circuit according to claim 6, characterized in that, The DC-DC module further includes a second overvoltage protection unit, which includes a second operational amplifier. The input terminal of the second operational amplifier is connected to the first low-voltage output port, and the output terminal of the second operational amplifier is connected to the overvoltage shutdown signal input terminal of the DC-DC driver chip.

8. A vehicle-mounted DC-DC bidirectional isolation switch circuit according to claim 6, characterized in that, The DC-DC module further includes a DC-DC voltage acquisition unit and a DC-DC current acquisition unit. The signal input terminals of the DC-DC voltage acquisition unit and the DC-DC current acquisition unit are both connected to the first low-voltage output port. The signal output terminal of the DC-DC voltage acquisition unit is connected to the voltage signal input terminal of the main control chip, and the signal output terminal of the DC-DC current acquisition unit is connected to the current signal input terminal of the main control chip.

9. A vehicle-mounted DC-DC bidirectional isolation switch circuit according to claim 6, characterized in that, The main control chip is equipped with a CAN communication port, which is connected to the CAN module to output corresponding operating status information and / or receive external control commands.

10. A control method for an on-board DC-DC bidirectional isolation switch circuit, characterized in that, The control method, applied to a vehicle-mounted DC-DC bidirectional isolation switch circuit as described in any one of claims 1-9, includes: The system acquires the output voltage and output current parameters corresponding to the first low-voltage output port. When the output voltage parameter of the first low-voltage output port exceeds a preset overvoltage threshold, the system controls the DC-DC module to shut down the output and controls the bidirectional switch module to disconnect the connection between the first low-voltage output port and the second low-voltage output port. When the output current parameter of the first low-voltage output port exceeds a preset overcurrent threshold, or when the output voltage parameter of the first low-voltage output port is lower than a preset undervoltage threshold, the system controls the DC-DC module to shut down the output and controls the bidirectional switch module to disconnect the connection between the first low-voltage output port and the second low-voltage output port. Obtain the second power supply status parameter corresponding to the second low-voltage output port. When the second power supply status parameter of the second low-voltage output port meets the preset abnormal conditions, control the bidirectional switch module to automatically disconnect the connection between the first low-voltage output port and the second low-voltage output port. The switching current parameters and current direction parameters flowing through the bidirectional switching module are obtained. When the switching current parameters exceed the preset switching current threshold, the bidirectional switching module is controlled to disconnect the connection between the first low-voltage output port and the second low-voltage output port based on the current direction parameters. After either the first low-voltage output port or the second low-voltage output port is isolated by a fault, low-voltage power is supplied to the backup low-voltage power supply equipment through the low-voltage battery. When the vehicle's low-voltage system enters the power-off state, a disconnect command is sent to the bidirectional switch module, and the electrical detection results of the first low-voltage output port, the second low-voltage output port, and the bidirectional switch module are obtained. Based on the electrical detection results, it is determined whether the bidirectional switch module can disconnect normally.

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