Vehicle fault diagnosis circuit, diagnosis method and vehicle

Abstract

The invention discloses a vehicle fault diagnosis circuit, a diagnosis method and a vehicle. The vehicle fault diagnosis circuit comprises an auxiliary diagnosis power supply circuit, a high-side sampling circuit, a low-side sampling circuit, a coil loop current detection circuit, a coil, a high-side switch and a low-side switch. The auxiliary diagnosis power supply circuit is connected with the coil loop current detection circuit, and the auxiliary diagnosis power supply circuit is used for controlling the on-off of an auxiliary diagnosis power supply; the coil loop current detection circuit is connected with the first end of the coil, the first end of the coil is connected with the high-side switch, and the coil loop current detection circuit is used for detecting the current of a coil loop; the high-side sampling circuit is connected with the first end of the coil, and the high-side sampling circuit is used for collecting the high-side voltage of the coil; the low-side sampling circuit is connected with the second end of the coil, the second end of the coil is connected with the low-side switch, and the low-side sampling circuit is used for collecting the low-side voltage of the coil.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicles, and in particular relates to a vehicle fault diagnosis circuit, a diagnosis method and a vehicle. Background Art

[0002] The hydraulic brake system of a vehicle usually includes several solenoid valves, which are used to control the on and off of the nodes of the hydraulic circuit to generate different brake pressures. The movement of the solenoid valve is usually controlled by the electromagnetic force generated by the coil. For safety and failure consequences, the circuit that controls the on and off of the coil generally includes a high-side switch, a low-side switch, and a diagnostic circuit designed to diagnose switch circuit and coil failures.

[0003] An electronic control system may contain multiple coils, which are controlled by a common high-side switch and independent low-side switches. Usually, the high-side switch and the low-side switch are composed of NMOS and driven by an ASIC chip. However, the fault diagnosis of the ASIC requires turning on at least one of the high-side switch and the low-side switch, but the solenoid valve is not allowed to change its state at will during the vehicle driving process. At the same time, the opening of the solenoid valve will generate certain noise. Therefore, fault diagnosis can usually only be performed for a short time during the system power-on self-test process. Summary of the invention

[0004] An object of the present invention is to provide a vehicle fault diagnosis circuit, a diagnosis method and a vehicle, which can solve the technical problem in the prior art that fault diagnosis can only be performed for a short time during the system power-on self-test process.

[0005] According to a first aspect of the present invention, there is provided a vehicle fault diagnosis circuit, comprising an auxiliary diagnosis power supply circuit, a high-side sampling circuit, a low-side sampling circuit, a coil loop current detection circuit, a coil, a high-side switch and a low-side switch; The auxiliary diagnosis power supply circuit is connected to the coil loop current detection circuit, and the auxiliary diagnosis power supply circuit is used to control the on and off of the auxiliary diagnosis power supply; The coil loop current detection circuit is connected to the first end of the coil, the first end of the coil is connected to the high-side switch, and the coil loop current detection circuit is used to detect the current of the coil loop; The high-side sampling circuit is connected to the first end of the coil, and the high-side sampling circuit is used to collect the high-side voltage of the coil; The low-side sampling circuit is connected to the second end of the coil, the second end of the coil is connected to the low-side switch, and the low-side sampling circuit is used to collect the low-side voltage of the coil.

[0006] Optionally, the auxiliary diagnosis power supply circuit includes a composite transistor, and the composite transistor includes a first transistor and a second transistor; The auxiliary diagnostic power supply is respectively connected to the emitter of the second transistor and the first end of the first resistor, the base of the second transistor is respectively connected to the second end of the first resistor and the first end of the second resistor, the second end of the second resistor is connected to a control signal, and the control signal is used to control the on and off of the composite transistor; The collector of the second transistor is connected to the base of the first transistor and the emitter of the first transistor respectively, and the collector of the first transistor is connected to the coil loop current detection circuit.

[0007] Optionally, the first transistor is an NPN transistor, and the second transistor is a PNP transistor.

[0008] Optionally, the coil loop current detection circuit includes a third resistor, a fourth resistor, a fifth resistor, a first capacitor, and a second capacitor; The first end of the third resistor is connected to the first end of the fourth resistor and the collector of the first transistor respectively, and the second end of the third resistor is connected to the first end of the fifth resistor and the first end of the coil respectively; The second end of the fourth resistor is connected to the first end of the first capacitor and the first sampling port respectively, the second end of the fifth resistor is connected to the second end of the second capacitor and the second sampling port respectively, and the second end of the first capacitor and the second end of the second capacitor are grounded.

[0009] Optionally, the high-side sampling circuit includes a sixth resistor, a seventh resistor and a third capacitor; The first end of the sixth resistor is connected to the first end of the coil, the second end of the sixth resistor is respectively connected to the first end of the seventh resistor, the first end of the third capacitor and the third sampling port, and the second end of the seventh resistor and the second end of the third capacitor are grounded.

[0010] Optionally, the low-side sampling circuit includes an eighth resistor, a ninth resistor and a fourth capacitor; The first end of the eighth resistor is connected to the second end of the coil, the second end of the eighth resistor is respectively connected to the first end of the ninth resistor, the first end of the fourth capacitor and the fourth sampling port, and the second end of the ninth resistor and the second end of the fourth capacitor are grounded.

[0011] Optionally, the high-side switch comprises a first NMOS transistor, and the low-side switch comprises a second NMOS transistor.

[0012] According to a second aspect of the present invention, there is provided a diagnostic method using the vehicle fault diagnostic circuit according to the first aspect of the present invention, comprising: After the system is powered on, obtain the on-state of the auxiliary diagnostic power supply, the on-state of the high-side switch, and the on-state of the low-side switch; If the auxiliary diagnostic power supply is in an off state, the high-side switch is in an off state, and the low-side switch is in an off state, and the high-side voltage of the coil is greater than 2V, the fault type is determined to be a high-side MOS breakdown or a high-side short power supply; If the auxiliary diagnostic power supply is in the off state, the high-side switch is in the on state, and the low-side switch is in the off state, when the coil high-side voltage is greater than 9V and the coil low-side voltage is less than 2V, the fault type is determined to be a coil open circuit or a low-side MOS open fault; If the auxiliary diagnostic power supply is in the off state, the high-side switch is in the on state, and the low-side switch is in the off state, when the high-side voltage of the coil is less than 9V, the high-side switch is turned off and the auxiliary diagnostic power supply is turned on. When the high-side voltage of the coil is greater than 4V, the fault type is determined to be a high-side open circuit or a high-side drive fault. When the high-side voltage of the coil is less than 2V, the fault type is determined to be a high-side short to ground. If the auxiliary diagnostic power supply is in the off state, the high-side switch is in the on state, and the low-side switch is in the on state, when the coil high-side voltage is less than 2V, the fault type is determined to be a coil short circuit; when the coil high-side voltage is greater than 2V and the coil low-side voltage is greater than 2V, the fault type is determined to be a low-side MOS open circuit fault; If the auxiliary diagnostic power supply is in the on state, the high-side switch is in the off state, and the low-side switch is in the off state, and the difference between the two voltage values ​​output by the coil loop current detection circuit is greater than the threshold, the fault type is determined to be coil overcurrent.

[0013] According to a third aspect of the present invention, there is provided a diagnostic method using the vehicle fault diagnostic circuit according to the first aspect of the present invention, comprising: During the inspection process, obtain the on-state of the auxiliary diagnostic power supply, the on-state of the high-side switch, and the on-state of the low-side switch; If the auxiliary diagnostic power supply is in the on state, the high-side switch is in the off state, and the low-side switch is in the off state, when the high-side voltage of the coil is greater than 4V, the fault type is determined to be a high-side MOS breakdown or a high-side short power supply; when the high-side voltage of the coil is less than 2V, the fault type is determined to be a high-side short to ground; when the high-side voltage of the coil is greater than 2V and less than 4V and the low-side voltage of the coil is less than 2V, the fault type is determined to be a coil open circuit fault or a low-side MOS open fault; If the auxiliary diagnostic power supply is in the on state, the high-side switch is in the off state, and the low-side switch is in the on state, when the high-side voltage of the coil is less than 2V, the fault type is determined to be a coil short circuit; when the high-side voltage of the coil is greater than 2V and the low-side voltage of the coil is greater than 2V, the fault type is determined to be a low-side MOS open circuit fault; when the high-side voltage of the coil is greater than 2V, the low-side voltage of the coil is less than 2V and the difference between the two voltage values ​​output by the coil loop current detection circuit is greater than the threshold, the fault type is determined to be a coil overcurrent.

[0014] According to a fourth aspect of the present invention, a vehicle is provided, the vehicle comprising the vehicle fault diagnosis circuit according to the first aspect of the present invention.

[0015] The beneficial effect of the present invention is that the present invention can realize diagnosis and control the current passing through the coil by setting an auxiliary diagnosis power supply circuit to control the on and off of the auxiliary diagnosis power supply, so that the electromagnetic force is not enough to change the existing state of the solenoid valve, and then the coil can be detected without opening the high-side safety switch. At the same time, the diagnosis is controllable to avoid increasing the static working current. And when a short circuit fault occurs, the auxiliary diagnosis power supply can be turned off to improve safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a vehicle fault diagnosis circuit in an embodiment of the present invention.

[0017] Figure 2 It is a schematic diagram of a vehicle fault diagnosis circuit in an embodiment of the present invention.

[0018] Figure 3 It is a flow chart of system power-on fault diagnosis in an embodiment of the present invention.

[0019] Figure 4 It is a flow chart of the off-peak inspection fault diagnosis in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0021] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0022] The techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and devices should be considered as part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0023] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0024] In the specification and claims of the present invention, if the term "first" or "second" is involved, it may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the related objects are in an "or" relationship.

[0025] like Figure 1 As shown, this embodiment introduces a vehicle fault diagnosis circuit, including an auxiliary diagnosis power supply circuit, a high-side sampling circuit, a low-side sampling circuit, a coil loop current detection circuit, a coil, a high-side switch and a low-side switch.

[0026] The auxiliary diagnosis power supply circuit is connected to the coil loop current detection circuit, and the auxiliary diagnosis power supply circuit is used to control the on and off of the auxiliary diagnosis power supply.

[0027] The coil loop current detection circuit is connected to the first end of the coil, the first end of the coil is connected to the high-side switch, and the coil loop current detection circuit is used to detect the current of the coil loop.

[0028] The high-side sampling circuit is connected to the first end of the coil, and the high-side sampling circuit is used to collect the high-side voltage of the coil.

[0029] The low-side sampling circuit is connected to the second end of the coil, the second end of the coil is connected to the low-side switch, and the low-side sampling circuit is used to collect the low-side voltage of the coil.

[0030] like Figure 2As shown, the high-side switch and the low-side switch are composed of NMOS, and the drive is controlled by an ASIC chip. The high-side switch includes a first NMOS transistor DRVM1, which is turned on or off by the driving signal RCOIL_GATE1 to realize the opening or closing of the high-side switch. The low-side switch includes a second NMOS transistor DRVM2, which is turned on or off by the driving signal RCOIL_GATE2 to realize the opening or closing of the low-side switch.

[0031] The types of faults are divided into high-side switch faults, coil faults, and low-side switch faults. High-side faults include overcurrent, high-side open circuit, high-side short power supply, high-side short ground, etc. Coil faults include coil short circuit, coil open circuit, coil overload, etc. Low-side faults include low-side open circuit, low-side short power supply, low-side short ground, etc. The specific fault type is determined based on the sampling results of the high-side sampling circuit, the sampling results of the low-side sampling circuit, and the detection results of the coil loop current detection circuit.

[0032] The present invention sets an auxiliary diagnostic power supply circuit to control the on and off of the auxiliary diagnostic power supply, which can not only realize diagnosis but also control the current passing through the coil, so that its electromagnetic force is not enough to change the existing state of the solenoid valve, and then the coil can be detected without opening the high-side safety switch. At the same time, the diagnosis is controllable to avoid increasing the static working current. And when a short circuit fault occurs, the auxiliary diagnostic power supply can be turned off to improve safety.

[0033] like Figure 2 As shown, the auxiliary diagnosis power supply circuit in this embodiment includes a composite transistor, and the composite transistor includes a first transistor Q1A and a second transistor Q1B. The first transistor Q1A is an NPN transistor, and the second transistor Q1B is a PNP transistor.

[0034] The auxiliary diagnostic power supply VCC is respectively connected to the emitter of the second transistor Q1B and the first end of the first resistor R1, the base of the second transistor Q1B is respectively connected to the second end of the first resistor R1 and the first end of the second resistor R2, the second end of the second resistor R2 is connected to the control signal RCOIL_CTRL, and the control signal RCOIL_CTRL is used to control the on and off of the composite transistor.

[0035] The collector of the second transistor Q1B is connected to the base of the first transistor Q1A and the emitter of the first transistor Q1A respectively, and the collector of the first transistor Q1A is connected to the coil loop current detection circuit.

[0036] By switching the control signal RCOIL_CTRL between high and low levels, the on-off control of the composite transistor can be achieved, thereby turning on or off the auxiliary diagnosis power supply.

[0037] like Figure 2 As shown, in this embodiment, the coil loop current detection circuit includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, and a second capacitor C2.

[0038] The first end of the third resistor R3 is connected to the first end of the fourth resistor R4 and the collector of the first transistor Q1A respectively, and the second end of the third resistor R3 is connected to the first end of the fifth resistor R5 and the first end of the coil respectively.

[0039] The second end of the fourth resistor R4 is connected to the first end of the first capacitor C1 and the first sampling port RCOIL_TEST1 respectively, the second end of the fifth resistor R5 is connected to the second end of the second capacitor C2 and the second sampling port RCOIL_TEST2 respectively, and the second end of the first capacitor C1 and the second end of the second capacitor C2 are grounded.

[0040] The third resistor R3 is a high-precision sampling resistor. The voltage difference between the first sampling port RCOIL_TEST1 and the second sampling port RCOIL_TEST2 is proportional to the current flowing through the third resistor R3, thereby calculating the current of the coil loop.

[0041] In this embodiment, the high-side sampling circuit includes a sixth resistor R6, a seventh resistor R7 and a third capacitor C3. The first end of the sixth resistor R6 is connected to the first end of the coil, the second end of the sixth resistor R6 is respectively connected to the first end of the seventh resistor R7, the first end of the third capacitor C3 and the third sampling port RCOIL_SUP_FBK, and the second end of the seventh resistor R7 and the second end of the third capacitor C3 are grounded.

[0042] like Figure 2 As shown, the sixth resistor R6 collects the high-side voltage of the coil, and the sixth resistor R6 and the seventh resistor form a voltage divider circuit to convert the high-side voltage of the coil into a voltage within a voltage range that can be recognized by the single-chip microcomputer. The third capacitor C3 is used to filter out interference.

[0043] In this embodiment, the low-side sampling circuit includes an eighth resistor R8, a ninth resistor R9 and a fourth capacitor C4. The first end of the eighth resistor R8 is connected to the second end of the coil, the second end of the eighth resistor R8 is respectively connected to the first end of the ninth resistor R9, the first end of the fourth capacitor C4 and the fourth sampling port FR_NC_FBK, and the second end of the ninth resistor R9 and the second end of the fourth capacitor C4 are grounded.

[0044] like Figure 2 As shown, the eighth resistor R8 collects the coil low-side voltage, and the eighth resistor R8 and the ninth resistor R9 form a voltage divider circuit to convert the coil low-side voltage into a voltage within a voltage range that can be recognized by the single-chip microcomputer. The fourth capacitor is used to filter out interference.

[0045] The present invention can realize inspection during idle time and fault diagnosis when the system is powered on.

[0046] like Figure 3 As shown, this embodiment introduces a diagnostic method for a vehicle fault diagnosis circuit according to any embodiment of the present invention, which is a system power-on fault diagnosis, including: After the system is powered on, obtain the on-state of the auxiliary diagnostic power supply, the on-state of the high-side switch, and the on-state of the low-side switch; If the auxiliary diagnostic power supply is in an off state, the high-side switch is in an off state, and the low-side switch is in an off state, and the high-side voltage of the coil is greater than 2V, the fault type is determined to be a high-side MOS breakdown or a high-side short power supply; If the auxiliary diagnostic power supply is in the off state, the high-side switch is in the on state, and the low-side switch is in the off state, when the coil high-side voltage is greater than 9V and the coil low-side voltage is less than 2V, the fault type is determined to be a coil open circuit or a low-side MOS open fault; If the auxiliary diagnostic power supply is in the off state, the high-side switch is in the on state, and the low-side switch is in the off state, when the high-side voltage of the coil is less than 9V, the high-side switch is turned off and the auxiliary diagnostic power supply is turned on. When the high-side voltage of the coil is greater than 4V, the fault type is determined to be a high-side open circuit or a high-side drive fault. When the high-side voltage of the coil is less than 2V, the fault type is determined to be a high-side short to ground. If the auxiliary diagnostic power supply is in the off state, the high-side switch is in the on state, and the low-side switch is in the on state, when the coil high-side voltage is less than 2V, the fault type is determined to be a coil short circuit; when the coil high-side voltage is greater than 2V and the coil low-side voltage is greater than 2V, the fault type is determined to be a low-side MOS open circuit fault; If the auxiliary diagnostic power supply is in the on state, the high-side switch is in the off state, and the low-side switch is in the off state, and the difference between the two voltage values ​​output by the coil loop current detection circuit is greater than the threshold, the fault type is determined to be coil overcurrent.

[0047] RCOIL_CTRL OFF indicates that the auxiliary diagnostic power supply is off, and RCOIL_CTRL ON indicates that the auxiliary diagnostic power supply is on. RCOIL_GATE1 OFF indicates that the high-side switch is off, and RCOIL_GATE1 ON indicates that the high-side switch is on. RCOIL_GATE2 OFF indicates that the low-side switch is off, and RCOIL_GATE2 ON indicates that the low-side switch is on.

[0048] RCOIL_SUP_FBK is the high-side voltage of the coil collected by the high-side sampling circuit, FR_NC_FBK is the low-side voltage of the coil collected by the low-side sampling circuit, and RCOIL_TEST1 and RCOIL_TEST2 are two voltages collected by the coil loop current detection circuit.

[0049] like Figure 4 As shown, this embodiment introduces a diagnostic method for a vehicle fault diagnosis circuit according to any embodiment of the present invention, which is for idle inspection fault diagnosis, including: During the inspection process, obtain the on-state of the auxiliary diagnostic power supply, the on-state of the high-side switch, and the on-state of the low-side switch; If the auxiliary diagnostic power supply is in the on state, the high-side switch is in the off state, and the low-side switch is in the off state, when the high-side voltage of the coil is greater than 4V, the fault type is determined to be a high-side MOS breakdown or a high-side short power supply; when the high-side voltage of the coil is less than 2V, the fault type is determined to be a high-side short to ground; when the high-side voltage of the coil is greater than 2V and less than 4V and the low-side voltage of the coil is less than 2V, the fault type is determined to be a coil open circuit fault or a low-side MOS open fault; If the auxiliary diagnostic power supply is in the on state, the high-side switch is in the off state, and the low-side switch is in the on state, when the high-side voltage of the coil is less than 2V, the fault type is determined to be a coil short circuit; when the high-side voltage of the coil is greater than 2V and the low-side voltage of the coil is greater than 2V, the fault type is determined to be a low-side MOS open circuit fault; when the high-side voltage of the coil is greater than 2V, the low-side voltage of the coil is less than 2V and the difference between the two voltage values ​​output by the coil loop current detection circuit is greater than the threshold, the fault type is determined to be a coil overcurrent.

[0050] This embodiment introduces a vehicle, which includes a vehicle fault diagnosis circuit as described in any embodiment of the present invention.

[0051] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

[0052] Those of ordinary skill in the art will appreciate that the modules and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0053] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and equipment can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0054] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0055] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the embodiments of the present invention.

[0056] In addition, each functional module in the embodiment of the present invention may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0057] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of various embodiments of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical disks.

[0058] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

[0059] It should be understood that the size of the sequence number of each step in the content of the invention and the embodiments of the present invention does not absolutely mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention. For the purpose of example and description, the foregoing description of the implementation of the present disclosure has been given. The foregoing description is not exhaustive and is not intended to limit the present disclosure to the exact form disclosed. Various deformations and modifications may exist according to the above teachings, or various deformations and modifications may be obtained from the practice of the present disclosure. These embodiments are selected and described to illustrate the principles of the present disclosure and its practical application, so that those skilled in the art can use the present disclosure in various embodiments and various modifications suitable for the specific purpose conceived.

Claims

1. A vehicle fault diagnosis circuit, characterized in that: It includes an auxiliary diagnosis power supply circuit, a high-side sampling circuit, a low-side sampling circuit, a coil loop current detection circuit, a coil, a high-side switch and a low-side switch; The auxiliary diagnosis power supply circuit is connected to the coil loop current detection circuit, and the auxiliary diagnosis power supply circuit is used to control the on and off of the auxiliary diagnosis power supply; The coil loop current detection circuit is connected to the first end of the coil, the first end of the coil is connected to the high-side switch, and the coil loop current detection circuit is used to detect the current of the coil loop; The high-side sampling circuit is connected to the first end of the coil, and the high-side sampling circuit is used to collect the high-side voltage of the coil; The low-side sampling circuit is connected to the second end of the coil, the second end of the coil is connected to the low-side switch, and the low-side sampling circuit is used to collect the low-side voltage of the coil.

2. A vehicle fault diagnosis circuit according to claim 1, characterized in that: The auxiliary diagnosis power supply circuit includes a composite transistor, and the composite transistor includes a first transistor and a second transistor; The auxiliary diagnostic power supply is respectively connected to the emitter of the second transistor and the first end of the first resistor, the base of the second transistor is respectively connected to the second end of the first resistor and the first end of the second resistor, the second end of the second resistor is connected to a control signal, and the control signal is used to control the on and off of the composite transistor; The collector of the second transistor is connected to the base of the first transistor and the emitter of the first transistor respectively, and the collector of the first transistor is connected to the coil loop current detection circuit.

3. A vehicle fault diagnosis circuit according to claim 2, characterized in that: The first transistor is an NPN transistor, and the second transistor is a PNP transistor.

4. A vehicle fault diagnosis circuit according to claim 2, characterized in that: The coil loop current detection circuit includes a third resistor, a fourth resistor, a fifth resistor, a first capacitor, and a second capacitor; The first end of the third resistor is connected to the first end of the fourth resistor and the collector of the first transistor respectively, and the second end of the third resistor is connected to the first end of the fifth resistor and the first end of the coil respectively; The second end of the fourth resistor is connected to the first end of the first capacitor and the first sampling port respectively, the second end of the fifth resistor is connected to the second end of the second capacitor and the second sampling port respectively, and the second end of the first capacitor and the second end of the second capacitor are grounded.

5. A vehicle fault diagnosis circuit according to claim 1, characterized in that: The high-side sampling circuit includes a sixth resistor, a seventh resistor and a third capacitor; The first end of the sixth resistor is connected to the first end of the coil, the second end of the sixth resistor is respectively connected to the first end of the seventh resistor, the first end of the third capacitor and the third sampling port, and the second end of the seventh resistor and the second end of the third capacitor are grounded.

6. A vehicle fault diagnosis circuit according to claim 1, characterized in that: The low-side sampling circuit includes an eighth resistor, a ninth resistor and a fourth capacitor; The first end of the eighth resistor is connected to the second end of the coil, the second end of the eighth resistor is respectively connected to the first end of the ninth resistor, the first end of the fourth capacitor and the fourth sampling port, and the second end of the ninth resistor and the second end of the fourth capacitor are grounded.

7. A vehicle fault diagnosis circuit according to claim 1, characterized in that: The high-side switch includes a first NMOS transistor, and the low-side switch includes a second NMOS transistor.

8. A diagnostic method using a vehicle fault diagnostic circuit as claimed in any one of claims 1 to 7, characterized in that: include: After the system is powered on, obtain the on-state of the auxiliary diagnostic power supply, the on-state of the high-side switch, and the on-state of the low-side switch; If the auxiliary diagnostic power supply is in an off state, the high-side switch is in an off state, and the low-side switch is in an off state, and the high-side voltage of the coil is greater than 2V, the fault type is determined to be a high-side MOS breakdown or a high-side short power supply; If the auxiliary diagnostic power supply is in the off state, the high-side switch is in the on state, and the low-side switch is in the off state, when the coil high-side voltage is greater than 9V and the coil low-side voltage is less than 2V, the fault type is determined to be a coil open circuit or a low-side MOS open fault; If the auxiliary diagnostic power supply is in the off state, the high-side switch is in the on state, and the low-side switch is in the off state, when the high-side voltage of the coil is less than 9V, the high-side switch is turned off and the auxiliary diagnostic power supply is turned on. When the high-side voltage of the coil is greater than 4V, the fault type is determined to be a high-side open circuit or a high-side drive fault. When the high-side voltage of the coil is less than 2V, the fault type is determined to be a high-side short to ground. If the auxiliary diagnostic power supply is in the off state, the high-side switch is in the on state, and the low-side switch is in the on state, when the coil high-side voltage is less than 2V, the fault type is determined to be a coil short circuit; when the coil high-side voltage is greater than 2V and the coil low-side voltage is greater than 2V, the fault type is determined to be a low-side MOS open circuit fault; If the auxiliary diagnostic power supply is in the on state, the high-side switch is in the off state, and the low-side switch is in the off state, and the difference between the two voltage values ​​output by the coil loop current detection circuit is greater than the threshold, the fault type is determined to be coil overcurrent.

9. A diagnostic method using a vehicle fault diagnosis circuit as claimed in any one of claims 1 to 7, characterized in that: include: During the inspection process, obtain the on-state of the auxiliary diagnostic power supply, the on-state of the high-side switch, and the on-state of the low-side switch; If the auxiliary diagnostic power supply is in the on state, the high-side switch is in the off state, and the low-side switch is in the off state, when the high-side voltage of the coil is greater than 4V, the fault type is determined to be a high-side MOS breakdown or a high-side short power supply; when the high-side voltage of the coil is less than 2V, the fault type is determined to be a high-side short to ground; when the high-side voltage of the coil is greater than 2V and less than 4V and the low-side voltage of the coil is less than 2V, the fault type is determined to be a coil open circuit fault or a low-side MOS open fault; If the auxiliary diagnostic power supply is in the on state, the high-side switch is in the off state, and the low-side switch is in the on state, when the high-side voltage of the coil is less than 2V, the fault type is determined to be a coil short circuit; when the high-side voltage of the coil is greater than 2V and the low-side voltage of the coil is greater than 2V, the fault type is determined to be a low-side MOS open circuit fault; when the high-side voltage of the coil is greater than 2V, the low-side voltage of the coil is less than 2V and the difference between the two voltage values ​​output by the coil loop current detection circuit is greater than the threshold, the fault type is determined to be a coil overcurrent.

10. A vehicle, characterized in that: The vehicle comprises a vehicle fault diagnosis circuit as described in any one of claims 1-7.

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