Fault detection method and system for vehicle high voltage electronic fuse

Abstract

This invention provides a fault detection method and system for high-voltage electronic fuses in vehicles. By dividing the pre-charging circuit's operation into two stages within two different time periods, various faults in the circuit can be detected in advance. This allows for the orderly elimination of short-circuit faults and large-capacity load faults in the high-voltage circuit. After the drive control signal of the power switch in the main circuit of the electronic fuse is activated, the pre-charging circuit is simultaneously shut down. Furthermore, overcurrent detection is effectively performed, thereby ensuring the safety and reliability of the vehicle's high-voltage power distribution system when it is connected. This invention, through hardware and software improvements and design of the electronic fuse detection system, can sequentially detect various faults that are prone to occur when the high-voltage circuit is connected, and promptly perform safety disconnection and protection to ensure the safety and reliability of the vehicle's high-voltage power distribution system.

Description

Technical Field

[0001] This invention belongs to the field of power distribution fault detection in new energy vehicles, and particularly relates to a fault detection method and system for high-voltage electronic fuses in vehicles. Background Technology

[0002] Currently, traditional mechanical thermal fuses have unavoidable drawbacks, such as weak self-reset capability and limited operation at relatively low currents. Emerging electronic fuses (eFuses) offer a better solution. eFuse design is based on a simple concept: detecting current by measuring the voltage across a known resistor, and then cutting off the current via a field-effect transistor (FET) when the current exceeds a design limit. eFuses possess self-testing characteristics, flexibility, and reliability that thermal fuses cannot achieve. Their advantage lies in their fast response speed, effectively protecting downstream loads. Relays, on the other hand, are mechanical and have slow response times; the load may be damaged before the circuit is disconnected.

[0003] In the field of vehicle power distribution, the high-voltage power battery of new energy vehicles is the source of energy and power for the vehicle. Its high-voltage operating range is generally 250V to 750V. The PDU (Power Distribution Unit) distributes the power battery's power to various components, such as DC-DC converters, oil pumps, air pumps, PTCs, and motor controllers. Traditional PDUs use relays / contactors and fuses. However, this type of PDU cannot detect the operating status of the high-voltage circuit. Especially when a fault occurs in the high-voltage circuit, it cannot detect common problems such as short circuits, load faults, and overcurrent faults in time, nor can it protect the components in the circuit that need power distribution in time. When a problem occurs in the vehicle's high-voltage circuit, it can easily escalate into a more serious safety accident in a short period of time, at which point human intervention may be impossible.

[0004] Therefore, in order to improve the safety of circuits and operating equipment when electronic fuses are connected to high-voltage power distribution circuits, it is necessary to design a fault detection method for electronic fuses in vehicle high-voltage circuits to effectively detect various fault problems that are prone to occur in high-voltage circuits, thereby ensuring the safe connection of electronic fuses and the normal operation of vehicle high-voltage power distribution lines. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] This invention provides a fault detection method and system for high-voltage electronic fuses in vehicles. By improving and designing the hardware and software of the electronic fuse, it can sequentially detect various faults that are prone to occur when the high-voltage circuit is connected, and promptly perform safety disconnection and protection to ensure the safety and reliability of the vehicle's high-voltage power distribution system.

[0007] (II) Technical Solution

[0008] This invention provides a fault detection method for a vehicle high-voltage electronic fuse, wherein the main circuit and pre-charge circuit of the electronic fuse are connected in parallel, and the fault detection method includes:

[0009] Step 1: Start the electronic fuse and enter the first stage of pre-charge. Set the drive control signal Pre_EF of the power switch tube in the pre-charge circuit to the active state to enable the pre-charge function of the electronic fuse.

[0010] Step 2: After timing T1, check whether the main circuit output voltage acquisition value EF_VOUT is greater than K1 times the input voltage EF_VIN. If yes, proceed to the next step 3. If no, it indicates that a load pre-charge short circuit fault has occurred. After reporting the fault, shut down the pre-charge circuit and end the program.

[0011] Step 3: Enter the second stage of pre-charge. After timing to T2, check whether the main circuit output voltage acquisition value EF_VOUT is greater than K2 times the input voltage EF_VIN. If yes, proceed to the next step 4. If no, it indicates that a load output capacitor fault has occurred. After reporting the fault, shut down the pre-charge circuit and end the program. The pre-charge coefficient K2 is greater than K1.

[0012] Step 4: If the pre-charge circuit of the electronic fuse is working normally, set the drive control signal ON_EF of the power switch in the main circuit to the active state and set Pre_EF to the inactive state. Check if there is an overcurrent fault detection signal. If yes, it indicates that a load output overcurrent fault has occurred. After reporting the fault, shut down the pre-charge circuit and end the program. If no, start the electronic fuse and the electronic fuse enters normal working state.

[0013] Preferably, T2 is greater than T1, and both T1 and T2 are in the millisecond range. The actual values ​​of T1 and T2 can be calibrated and modified according to the power supply circuit.

[0014] Preferably, the main circuit comprises a MOSFET module consisting of one or more SiC MOSFETs connected in parallel.

[0015] Preferably, the pre-charge routing resistor R3, resistor R4 and SiC MOSFET Qr are connected in series, and resistors R3 and R4 are cooled by the aluminum substrate on the back of the PCB.

[0016] Preferably, the judgment functions in steps 2 and 3 are implemented through an input / output voltage comparison circuit. This circuit includes voltage comparator U1-A, voltage comparator U1-B, and resistors Rs1 to Rs6. The output voltage acquisition value EF_VOUT is connected to the inverting input of voltage comparator U1-A via Rs1. Rs2 is connected to the input voltage EF_VIN and the non-inverting input of voltage comparator U1-A, respectively. Rs3 is connected to the non-inverting input of voltage comparator U1-A and digital ground, respectively. The output voltage acquisition value EF_VOUT is connected to the inverting input of voltage comparator U1-B via Rs4. Rs5 is connected to the input voltage EF_VIN and the non-inverting input of voltage comparator U1-B, respectively. Rs6 is connected to the non-inverting input of voltage comparator U1-B and digital ground, respectively. The output signal of voltage comparator U1-A is UP_K1. VIN, the output signal of voltage comparator U1-B is UP_K2 VIN.

[0017] Preferably, the input-output voltage comparison circuit further includes four capacitors C1-C4, one end of each capacitor C1-C4 is respectively disposed at the four signal input terminals of voltage comparator U1-A and voltage comparator U1-B, and the other end of each capacitor is grounded.

[0018] Preferably, the overcurrent fault detection function in step 4 is implemented through an overcurrent detection circuit. The overcurrent detection circuit includes a voltage reference source U2, an operational amplifier circuit U3, resistors Rn1~Rn2, and a voltage comparator circuit U4. The voltage reference source circuit U2 includes a TL431 and a resistor Rn, which is used to output a reference voltage Vref. The non-inverting input of the operational amplifier circuit U3 is connected to the reference voltage Vref, and the inverting input is connected to one end of resistors Rn1 and Rn2. The other end of resistor Rn1 is grounded, and the other end of resistor Rn2 is connected to the output terminal of the operational amplifier circuit U3. The non-inverting input of the voltage comparator circuit U4 is connected to the output terminal of the operational amplifier circuit U3, and the inverting input of the voltage comparator circuit U4 is connected to the detection current value EF_Current output by the electronic fuse isolation converter. The output signal of the voltage comparator circuit U4 is OV_Current.

[0019] Preferably, after the start-up process in step 4 is completed, the monitoring system of the electronic fuse can normally detect the working status of the electronic fuse and obtain the working status of the power distribution circuit by monitoring the working status of the electronic fuse.

[0020] In another aspect, the present invention also discloses a fault detection system for a vehicle high-voltage electronic fuse, comprising at least one processor; and at least one memory communicatively connected to the processor, wherein: the memory stores program instructions executable by the processor, and the processor can execute the fault detection method for a vehicle high-voltage electronic fuse described above by calling the program instructions.

[0021] Preferably, the vehicle is a new energy vehicle, and the high voltage operating range of the electronic fuse is 250V~750V.

[0022] In another aspect, the present invention also discloses a vehicle comprising the fault detection system for a vehicle high-voltage electronic fuse as described in any of the preceding claims.

[0023] (III) Beneficial Effects

[0024] The fault detection method and system for high-voltage electronic fuses in vehicles of the present invention have the following advantages:

[0025] 1) To address the issues of short circuit faults, large load capacitor faults, and overcurrent faults that are prone to occur when the high-voltage electronic fuse of a vehicle battery is turned on, this invention employs a pre-charging circuit and its corresponding detection circuit to ensure the normal operation of the eFuse module's power circuit. The pre-charging circuit can determine whether there is a short circuit or large capacitor fault in the load. Starting the eFuse module requires first turning on the pre-charging circuit. From a microscopic perspective (mS level), the pre-charging circuit is a process of slowly increasing output voltage. Therefore, the pre-charging is divided into two stages, which is beneficial for judging the state of the circuit and thus avoids the current surge or other damage to the circuit caused by directly turning on the eFuse main circuit MOSFET. This makes the pre-charging circuit a necessary step for turning on the eFuse module. Furthermore, the overcurrent detection circuit sets a current limit value for the current flowing through the eFuse circuit, ensuring the maximum current value of the power circuit in hardware. Compared to setting a current threshold in software, its reliability is higher. By optimizing the startup of the eFuse module, the operation of the pre-charging circuit is divided into two stages within two different time periods, which can detect various faults in the circuit in advance, so as to systematically eliminate short circuit faults and large load capacitor faults in the high-voltage circuit. After the drive control signal ON_EF of the power switch in the main circuit of the eFuse is turned on, the pre-charging circuit is turned off at the same time, and then the overcurrent judgment is effectively performed, thereby ensuring the safety and reliability of the vehicle's high-voltage power distribution system when it is turned on.

[0026] 2) After troubleshooting the connection fault, the detection system of this invention can detect the operating status (temperature, voltage, current) of the eFuse module. By monitoring the operating status of the eFuse module, the operating status of the power distribution circuit can be obtained. The eFuse module has internal temperature detection, current detection, and voltage detection functions. By obtaining the relevant parameter values ​​of the module, faults can be analyzed and detected. Furthermore, the current of the eFuse circuit can be monitored in real time, so the dynamic changes in power during load operation can be obtained through the current and output voltage of the eFuse. In addition, the input and output signals of the electronic fuse of this invention are electrically isolated from the external drive and acquisition signals. This effectively isolates interference caused by high-voltage signals, thus not affecting the fault detection function of the eFuse control terminal. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the system structure of the high-voltage electronic fuse used in new energy vehicles in this invention.

[0029] Figure 2 This is a schematic diagram of the overcurrent detection circuit in the fault detection system of this invention;

[0030] Figure 3 This is a schematic diagram of the input-output voltage comparison circuit in the fault detection system of this invention;

[0031] Figure 4 This is a flowchart of the fault detection method for high-voltage electronic fuses in vehicles according to the present invention;

[0032] Figure 5 This is the curve showing the change of the output voltage of the eFuse module over time during the pre-charging process, as detected by the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] Each power distribution circuit in the PDU of this invention consists of one or more electronic fuses (eFuse modules); by detecting and controlling the state of the electronic fuses, the power distribution safety problem in the PDU power circuit can be effectively solved.

[0035] In the power distribution circuit of the power distribution unit of new energy vehicles, the voltage is relatively high compared to that of traditional gasoline vehicles, with the high-voltage operating range generally between 250V and 750V. Through long-term observation and analysis of fault waveforms in the high-voltage circuit, the inventors discovered that when a fault occurs in the high-voltage circuit, especially before and after the fuse is activated, short-circuit faults, load faults, and overcurrent faults are prone to occur. These problems can escalate due to delayed fault detection and protection. Therefore, to protect the expensive electronic components in the system and prevent the escalation of high-voltage circuit faults, this invention specifically designs a fault detection method and system for vehicle high-voltage electronic fuses.

[0036] As the main device for fault detection, the structure of the high-voltage electronic fuse eFuse module for new energy vehicles in this invention is as follows: Figure 1As shown, each eFuse module includes a SiC MOSFET module, a buffer circuit, a pre-charge circuit, a temperature acquisition circuit, a current acquisition circuit, an input voltage acquisition circuit, an output voltage acquisition circuit, an isolation drive circuit, and a signal isolation circuit. The SiC MOSFET module, which serves as the main circuit, is composed of multiple SiC MOSFETs connected in parallel. It determines the eFuse module's drive current capability, and its main circuit is connected to the high-voltage input and output signals HV_IN and HV_OUT. The buffer circuit is composed of capacitor C1, resistor R1, resistor R2, and capacitor C2 connected in series. The series connection of capacitors C1 and C2 increases the circuit's withstand voltage. The series connection of resistors R1 and R2 reduces the power handled by half compared to a single resistor of the same resistance value. The pre-charge circuit consists of resistors R3 and R4 connected in series with the power switch Qr, where Qr is a SiC MOSFET. Resistors R3 and R4 are cooled by the aluminum substrate on the back of the PCB because the pre-charge circuit can cause significant heat generation in R3 and R4 after a fault is detected, thus requiring improved heat dissipation performance of the series resistors. The drive control signal for the pre-charge circuit is Pre_EF. The Pre_EF input from the low-voltage side is isolated into signal S2 by the isolation drive circuit. The temperature acquisition circuit is located near the MOSFET and is used to detect the overall temperature of the eFuse module. The temperature acquisition circuit converts the module's temperature value into a voltage value, which is then converted into signal EF_Temp after signal isolation. The current acquisition circuit can acquire the current value flowing through the eFuse module. The acquisition circuit converts the current value Current into the corresponding voltage through a conversion relationship, which is then converted into signal EF_Current after isolation. The input and output voltage acquisition circuits are similar. The circuit divides the input HV_IN and output HV_OUT using resistors and isolates them into signals EF_VIN and EF_VOUT, respectively. The drive control signal ON_EF from the low-voltage side is used to drive the SiC MOSFET. The MOSFET module, after passing through the isolation drive circuit, becomes a high-voltage signal S1. This signal S1 drives the SiC MOSFET module and controls the gate of the SiC MOSFET, in accordance with the present invention. Figure 1 For example, its SiCMOSFET is an enhancement-mode NMOS transistor. If signal S1 needs to turn on the NMOS transistor, it needs to be greater than (Vgs + HV_OUT). Vgs is the gate-source drive voltage difference of the SiCMOSFET transistor. The voltage input HV_IN and voltage output HV_OUT of the high-voltage circuit are connected to the drain and source of each parallel MOS transistor Q1~Qn in the SiCMOSFET module, respectively. HV_OUT is the output voltage of the real-time detected eFuse connected to the high-voltage main circuit.

[0037] In the eFuse module, the input signals ON_EF and Pre_EF are the low-voltage side control signals for the main circuit and pre-charge circuit of the eFuse module, respectively, used to generate the corresponding drive signals S1-S2 on the high-voltage side. HV_IN and HV_OUT are the voltage input and voltage output terminals of the eFuse module connected to the vehicle's high-voltage line. The output signals EF_Temp, EF_Current, EF_VIN, and EF_VOUT are the acquisition signals for the temperature, current, voltage input, and voltage of the MOSFET output to the low-voltage side by the eFuse module, respectively. It should be noted that through the high-low voltage signal conversion and isolation of the isolation drive circuit and signal isolation circuit, the input and output signals of the electronic fuse of this invention have achieved high-low voltage electrical isolation design from the external drive and acquisition signals. This can effectively isolate the interference caused by high-voltage signals, thereby not affecting the fault detection function of the low-voltage control terminal of the eFuse and the on / off control function of the high-voltage MOSFET.

[0038] When the electronic fuse is activated to connect the high-voltage circuit, before ON_EF is set to the active state (i.e., before the high-voltage side signal S1 triggers the MOSFET to turn on), in order to detect faults in the high-voltage circuit and protect the main circuit in advance, this invention first sets Pre_EF to the active state to start the pre-charge function, and designs an input / output voltage comparison circuit, thereby using the output UP_K1... VIN and UP_K2 The VIN signal controls the pre-charge circuit signal S2 to perform normal shutdown of the pre-charge circuit and fault diagnosis of the high-voltage circuit. The output voltage change can be obtained from the output of the input-output voltage comparison circuit. By comparing the change with the time parameter, it can be determined whether the change rate of the pre-charge voltage meets the requirements. The load status can be analyzed based on the change rate of the output voltage.

[0039] Specifically, the input / output voltage comparison circuit is as follows: Figure 3 As shown, the positive input of voltage comparator U1-A is The negative input is the output voltage of the eFuse; the positive input of the voltage comparator U1-B is... The negative input is the output voltage of the eFuse. Rs2 is connected to the EF_VIN signal and the non-inverting input of voltage comparator U1-A, respectively. Rs3 is connected to the non-inverting input of voltage comparator U1-A and digital ground, respectively. Rs5 and Rs6 are connected similarly. EF_VOUT is connected to the inverting inputs of voltage comparators U1-A and U1-B through resistors Rs1 and Rs4, respectively. The first-stage pre-charge coefficient K1 and the second-stage pre-charge coefficient K2 are respectively:

[0040]

[0041]

[0042]

[0043]

[0044] Furthermore, coefficient K2 > K1, representing the two stages of pre-charge respectively. The first stage pre-charge coefficient K1 represents the first stage, and the second stage pre-charge coefficient K2 represents the second stage. It proportionally divides the detected input voltage acquisition value EF_VIN into... and Within the first preset time T1, when the output voltage acquisition value EF_VOUT is greater than K1 times the input voltage acquisition value EF_VIN, the output signal UP_K1 of the voltage comparator U1-A is activated. When the VIN level changes from high to low, it indicates that the first stage of pre-charging is complete. Within the second preset time T2, when the output voltage acquisition value EF_VOUT is greater than the input voltage acquisition value EF_VIN by K2, the output signal UP_K2 of the voltage comparator U1-B is activated. When VIN changes from high to low, it indicates that the second stage of pre-charge is working normally and pre-charge is complete. This sets Pre_EF to an invalid state, shuts off the pre-charge circuit, and connects the high-voltage circuit through the drive control signal ON_EF of the power switch in the main circuit. Capacitors C1~C4 are filter capacitors, and VCC is the power supply voltage for the two voltage comparators.

[0045] Therefore, it can be seen that the eFuse module of this invention needs to be pre-charged during the opening process; after the pre-charge is completed, the MOSFET module of the main circuit is then turned on. In order to prevent the impact of large current, the pre-charge circuit needs to judge the pre-charge process during operation. The method adopted is to divide the pre-charge into two processes: when the time T1 is completed, analyze the change of the ratio of the output voltage value to the input voltage during the pre-charge process. When the output voltage acquisition value EF_VOUT is greater than 1, the pre-charge is turned on. If the time is right, it indicates that the first stage of pre-charge is working normally; otherwise, it indicates that there is a short circuit fault in the load; when the timer T2 is completed, the output voltage acquisition value EF_VOUT is greater than 1. If the voltage reading is within the specified range, it indicates that the second stage of pre-charging is working normally; otherwise, it indicates that there is a fault of excessive capacitance at the load connection. After the two pre-charging processes are completed, the SiC MOSFET module of the high-voltage main circuit is officially turned on, and the level of OV_Current is then judged to analyze whether there is an overcurrent fault in the circuit. If there is, the MOSFET is disconnected; if there is no overcurrent fault, it continues to work, and then the temperature change value EF_Temp and the current change value EF_Current of the SiC MOSFET module are monitored normally to ensure that the power distribution loop is working normally.

[0046] Specifically, after the pre-charging circuit is turned off, ON_EF will be set to an active state to enable timely overcurrent detection, such as... Figure 2 As shown, this invention also includes an overcurrent detection circuit, comprising a voltage reference source U2, an operational amplifier circuit U3, and a voltage comparator circuit U4. The voltage reference source circuit U2 is composed of a TL431 and a resistor Rn, and it generates a 2.5V reference voltage Vref through a Zener diode. The operational amplifier circuit amplifies Vref, and the amplified in-phase voltage is: Use this as the positive input of voltage comparator U4. The negative input signal of voltage comparator U4 is the corresponding output voltage value of the current flowing through the eFuse. When the current flowing through the eFuse exceeds the set voltage value... After this, an overcurrent fault can be identified, and the OV_Current signal output by U4 will be a low-level signal indicating the fault. Therefore, it can be seen that the overcurrent detection circuit sets a current limit for the current flowing through the eFuse high-voltage circuit. The hardware guarantees the maximum current value of the power supply circuit, which is more reliable and more suitable for use in the protection circuits of new energy vehicles than setting a current threshold in software.

[0047] High-voltage power distribution units (PDUs) are composed of eFuse modules, and typically one eFuse module controls one power circuit; the internal circuitry of an eFuse module is as follows: Figure 1 As shown, the module's internal and external signals are electrically isolated; the module's temperature, input and output voltage, and current can all be monitored in real time. Figure 2 It is an overcurrent detection circuit; Figure 3 This is a comparison circuit between the output voltage and the input voltage during the output voltage rise process; when the PDU distributes power, it needs to first turn on the corresponding eFuse module; when the pre-charge circuit is working in the first stage, that is, if the output voltage rises to within time T1... The above is UP_K1 A low VIN signal indicates that the first stage of pre-charge is normal; when the pre-charge circuit operates in the second stage, that is, if the output voltage rises to a certain level within time T2... The above, i.e., UP_K2 A low VIN signal indicates that the second stage of precharge is normal. The time parameters T1 and T2 are both in the millisecond range, with T2 > T1. The actual values ​​of T1 and T2 can be modified according to the power supply circuit calibration. By dividing the precharge into two stages, the reliability of the precharge is ensured, and the load status is also obtained simultaneously. This creates the necessary conditions for the normal opening of the eFuse module. After opening the eFuse module, [the following steps are taken]. Figure 2The OV_Current level status of the overcurrent detection circuit can determine whether there is an overcurrent fault in the circuit. If so, the eFuse module will be cut off in time to protect the downstream circuit. If not, it will continue to work and continuously monitor the current, voltage and temperature of the circuit and the eFuse module during subsequent operation.

[0048] exist Figure 1-3 Building upon existing hardware improvements, this invention further discloses a fault detection method for high-voltage electronic fuses in vehicles. Some of the logical judgment functions can be implemented using a controller such as an MCU, allowing for flexible selection without relying on... Figure 2-3 The circuit shown implements the parameter comparison function to save hardware costs. Of course, this invention can also be implemented in other ways. Figure 2-3 The circuit implements the same function as the corresponding steps.

[0049] See Figure 4 As shown, the fault detection method for high-voltage electronic fuses in vehicles according to the present invention specifically includes the following steps:

[0050] Step 1: Start the electronic fuse and enter the first stage of pre-charge. Set the drive control signal Pre_EF of the power switch tube in the pre-charge circuit to the active state to enable the pre-charge function of the electronic fuse.

[0051] Step 2: After timer T1, check UP_K1. If the VIN level is low, proceed to step 3. If not, it indicates a load precharge short circuit fault. After reporting the fault, shut down the precharge circuit and end the program.

[0052] Specifically, in step 2, UP_K1 When VIN is low, it indicates that the output voltage acquisition value EF_VOUT is greater than the input voltage acquisition value EF_VIN by a factor of K1. K1 is the first-stage pre-charge coefficient less than 1, which can be preset in the software or determined by... Figure 3 The resistors Rs2 and Rs3 shown are connected in parallel to achieve this.

[0053] Step 3: Enter the second stage of pre-charging. The timer continues counting until T2, then UP_K2 is detected. If the VIN level is low, proceed to step 4. If not, it indicates a load output capacitor fault. After reporting the fault, shut down the pre-charge circuit and end the program.

[0054] Specifically, in step 3, UP_K2 When VIN is low, it indicates that the output voltage acquisition value EF_VOUT is greater than K2 times the input voltage acquisition value EF_VIN. K2 is the second-stage pre-charge coefficient less than 1, and K2 > K1, T2 > T1. These values ​​can be preset in the software or determined by... Figure 3 The resistors Rs5 and Rs6 shown are connected in parallel to achieve this.

[0055] Step 4: If the pre-charge circuit of the electronic fuse is working normally, set the drive control signal ON_EF of the power switch in the main circuit to the active state and the Pre_EF to the inactive state, and check if there is an overcurrent fault detection signal (i.e., the OV_Current signal is low). If yes, it indicates that a load output overcurrent fault has occurred. After reporting the fault, shut down the pre-charge circuit and end the program; if no, start the electronic fuse and end the operation. The electronic fuse enters normal working state.

[0056] Specifically, in step 4, after no circuit fault is found during the pre-charge stage, the present invention shuts down the pre-charge circuit and performs overcurrent detection after setting ON_EF to the active state. This avoids prolonged operation with high current after the high-voltage circuit is opened, thereby ensuring that the electronic fuse enters a normal working state. Furthermore, after the startup process in step 4 is completed, the eFuse detection system of the present invention can normally detect the operating status (temperature, voltage, current) of the eFuse module. By monitoring the operating status of the eFuse module, the operating status of the power distribution circuit can be obtained.

[0057] Furthermore, the overcurrent detection in step 4 can be achieved through the preferred method of this invention. Figure 2 The similar hardware comparison circuit shown can also be implemented using the software comparison function of the MCU controller, thereby further reducing hardware costs.

[0058] See Figure 5 As shown, during the pre-charge phase, the output voltage of the eFuse module of this invention reaches the input voltage K1 (K1 is the proportional coefficient) at time t1' and reaches the input voltage K2 (K2 is the proportional coefficient) at time t2'; the final value of the output voltage HV_OUT is the input voltage HV_IN, that is, the two correspond to the output voltage acquisition value EF_VOUT and the input voltage acquisition value EF_VIN respectively; when the timer value T1 in the control module > t1', that is, UP_K1 When VIN is low, the first stage of pre-charge is complete. If T1 < t1', it means the output voltage did not rise within the preset time T1, indicating a short circuit fault in the preceding and following circuits. When the timer value T2 in the control module > t2', i.e., UP_K2... When VIN is at a low level, the second stage of pre-charging is complete. The main circuit can be connected via signal S1 to detect if there is an overcurrent fault. If T2 < t2', it means that the output voltage has not reached the predetermined value within the preset time T2. The input capacitance of the load is too large, which affects the rise of HV_OUT. At this time, there is a load output capacitance fault. The pre-charging time needs to be readjusted or the large load capacitance problem needs to be manually eliminated to avoid further development into a more serious safety accident.

[0059] In another aspect, the present invention also claims a fault detection system for a vehicle high-voltage electronic fuse, comprising at least one processor; and at least one memory communicatively connected to the processor, wherein the memory stores program instructions executable by the processor, and the processor invokes the program instructions to execute the fault detection method for a vehicle high-voltage electronic fuse of the present invention.

[0060] Specifically, the vehicle of this invention is preferably a new energy vehicle, in which the high-voltage operating range of the efuse module in the PDU is 250V~750V, which can actually be used for high-voltage detection below 1000V (although the withstand voltage of the MOSFET can reach 1200V, it is generally derating for use in 800V systems). In addition, in special vehicles such as rail transit, the high-voltage operating range of the SiC MOSFET module in the efuse module can even reach about 1700V.

[0061] Compared with the prior art, the advantages of the present invention are as follows:

[0062] 1. To ensure the normal operation of the eFuse module power supply in the 250V~750V high-voltage circuit, this invention employs a pre-charging circuit before the eFuse main circuit is turned on. The pre-charging circuit can determine whether there is a short circuit or a fault in the large capacitor at the load end. Starting the eFuse module requires first turning on the pre-charging circuit. From a microscopic perspective (mS level), the pre-charging circuit is a process of slowly increasing output voltage. Therefore, the pre-charging is divided into two stages, which is beneficial for judging various abnormal states of the circuit, thereby avoiding the current surge or other damage to the circuit caused by directly turning on the eFuse main circuit MOSFET.

[0063] 2. This invention shuts down the pre-charging circuit when the high-voltage circuit is normally connected, and also performs overcurrent detection in a timely manner. The overcurrent detection circuit sets a current limit value for the current flowing through the eFuse circuit, which guarantees the maximum current value of the power supply circuit in hardware. Compared with setting a current threshold in software, its hardware reliability is higher.

[0064] 3. After confirming that the eFuse is working properly, the eFuse module can detect the operating status (temperature, voltage, current). By monitoring the operating status of the eFuse module, the power, temperature and other operating status of the power distribution circuit can be obtained. In addition, the eFuse module is electrically isolated from the external drive and acquisition signals, which can effectively isolate signal interference. It also has a buffer circuit to prevent damage to the device from sudden voltage changes at the output terminal when the MOSFET is switched.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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; and these 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 the present invention.

Claims

1. A failure detection method for a vehicle high-voltage electronic fuse, characterized by, The main circuit and pre-charge circuit in the electronic fuse are connected in parallel, and the fault detection method includes: Step 1: Start the electronic fuse and enter the first stage of pre-charge. Set the drive control signal Pre_EF of the power switch tube in the pre-charge circuit to the active state to enable the pre-charge function of the electronic fuse. Step 2: After timing T1, check whether the output voltage acquisition value EF_VOUT of the main circuit is greater than K1 times the input voltage acquisition value EF_VIN. If yes, proceed to the next step 3. If no, it indicates that a load pre-charge short circuit fault has occurred. After reporting the fault, shut down the pre-charge circuit and end the program. Step 3: Enter the second stage of pre-charge. After timing to T2, check whether the output voltage acquisition value EF_VOUT of the main circuit is greater than K2 times the input voltage acquisition value EF_VIN. If yes, proceed to the next step 4. If no, it indicates that a load output capacitor fault has occurred. After reporting the fault, shut down the pre-charge circuit and end the program. The pre-charge coefficient K2 is greater than K1. Step 4: If the pre-charge circuit of the electronic fuse is working normally, set the drive control signal ON_EF of the power switch in the main circuit to the active state and set Pre_EF to the inactive state. Check if there is an overcurrent fault detection signal. If yes, it means that a load output overcurrent fault has occurred. After reporting the fault, shut down the pre-charge circuit and end the program. If no, start the electronic fuse and end the operation. The electronic fuse enters the normal working state. The judgment functions in steps 2 and 3 are implemented through an input / output voltage comparison circuit. This circuit includes voltage comparators U1-A and U1-B, and resistors Rs1 to Rs6. The output voltage sample value EF_VOUT is connected to the inverting input of voltage comparator U1-A via Rs1. Rs2 is connected to the input voltage EF_VIN and the non-inverting input of voltage comparator U1-A, respectively. Rs3 is connected to the non-inverting input of voltage comparator U1-A and digital ground, respectively. The output voltage sample value EF_VOUT is connected to the inverting input of voltage comparator U1-B via Rs4. Rs5 is connected to the input voltage EF_VIN and the non-inverting input of voltage comparator U1-B, respectively. Rs6 is connected to the non-inverting input of voltage comparator U1-B and digital ground, respectively. The output signal of voltage comparator U1-A is UP_K1. VIN, the output signal of voltage comparator U1-B is UP_K2 VIN.

2. The fault detection method for high-voltage electronic fuses in vehicles according to claim 1, characterized in that, T2 is greater than T1, and both T1 and T2 are in the millisecond range. The actual values ​​of T1 and T2 can be calibrated and modified according to the power supply circuit.

3. The fault detection method for vehicle high-voltage electronic fuses according to claim 1, characterized in that, The main circuit includes a MOSFET module consisting of one or more SiC MOSFETs connected in parallel.

4. The fault detection method for vehicle high-voltage electronic fuses according to claim 3, characterized in that, The pre-charge routing resistors R3 and R4 and the SiC MOSFET Qr are connected in series. Resistors R3 and R4 dissipate heat through the aluminum substrate on the back of the PCB.

5. The fault detection method for high-voltage electronic fuses in vehicles according to claim 1, characterized in that, The input-output voltage comparison circuit also includes four capacitors C1-C4. One end of each capacitor C1-C4 is respectively located at the four signal input terminals of voltage comparator U1-A and voltage comparator U1-B, and the other end of each capacitor is grounded.

6. The fault detection method for high-voltage electronic fuses in vehicles according to claim 1, characterized in that, The overcurrent fault detection function in step 4 is implemented through an overcurrent detection circuit, which includes a voltage reference source U2, an operational amplifier circuit U3, resistors Rn1~Rn2, and a voltage comparator circuit U4. The voltage reference source circuit U2 includes a TL431 and a resistor Rn, which is used to output a reference voltage Vref. The non-inverting input of the operational amplifier circuit U3 is connected to the reference voltage Vref, and the inverting input is connected to one end of resistors Rn1 and Rn2. The other end of resistor Rn1 is grounded, and the other end of resistor Rn2 is connected to the output terminal of the operational amplifier circuit U3. The non-inverting input of the voltage comparator circuit U4 is connected to the output terminal of the operational amplifier circuit U3, and the inverting input of the voltage comparator circuit U4 is connected to the detection current value EF_Current output by the electronic fuse isolation converter. The output signal of the voltage comparator circuit U4 is OV_Current.

7. The fault detection method for vehicle high-voltage electronic fuses according to claim 1, characterized in that, After the startup process in step 4 is completed, the monitoring system of the electronic fuse can normally detect the working status of the electronic fuse and obtain the working status of the power distribution circuit by monitoring the working status of the electronic fuse.

8. A fault detection system for high-voltage electronic fuses in vehicles, characterized in that, It includes at least one processor; and at least one memory communicatively connected to the processor, wherein: the memory stores program instructions executable by the processor, and the processor invokes the program instructions to execute the fault detection method for a vehicle high-voltage electronic fuse as described in any one of claims 1-7.

9. The fault detection system for vehicle high-voltage electronic fuses according to claim 8, characterized in that, The vehicle is a new energy vehicle, and the high voltage operating range of the electronic fuse is 250V~750V.

10. A vehicle, characterized in that, The vehicle includes a fault detection system for a vehicle high-voltage electronic fuse as described in any one of claims 8-9.

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