A vehicle fault diagnosis circuit, diagnosis method and vehicle

Abstract

The present invention discloses a vehicle fault diagnosis circuit, a diagnosis method and a vehicle. The vehicle fault diagnosis circuit 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 / 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.

Description

Technical Field

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

[0002] The hydraulic braking system of a vehicle usually includes several solenoid valves for controlling the on-off of hydraulic circuit nodes, thereby generating different braking pressures. The movement of the solenoid valve is usually controlled by the electromagnetic force generated by the coil. Considering safety and failure consequences, the circuit for controlling the on-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 faults.

[0003] An electronic control system may include multiple coils, and these coils are controlled by a shared high-side switch and respective independent low-side switches. Usually, the high-side switch and the low-side switch are composed of NMOS and are driven by an ASIC chip. However, the fault diagnosis of the ASIC requires at least one of the high-side switch and the low-side switch to be turned on. However, during vehicle driving, it is not allowed for the solenoid valve to change its state randomly, and at the same time, the opening of the solenoid valve will generate certain noise. Therefore, the fault diagnosis can usually only be carried out for a short time during the power-on self-check process of the system. 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 the fault diagnosis can only be carried out for a short time during the power-on self-check process of the system.

[0005] According to a first aspect of the present invention, there is provided 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;

[0006] 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-off of the auxiliary diagnosis power supply;

[0007] 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;

[0008] 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;

[0009] 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.

[0010] Optionally, the auxiliary diagnostic power supply circuit includes a composite transistor, and the composite transistor includes a first transistor and a second transistor;

[0011] 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 / off of the composite transistor;

[0012] The collector of the second transistor is respectively connected to the base of the first transistor and the emitter of the first transistor. The collector of the first transistor is connected to the coil loop current detection circuit.

[0013] Optionally, the first transistor is an NPN-type transistor, and the second transistor is a PNP-type transistor.

[0014] Optionally, the coil loop current detection circuit includes a third resistor, a fourth resistor, a fifth resistor, a first capacitor, and a second capacitor;

[0015] The first end of the third resistor is respectively connected to the first end of the fourth resistor and the collector of the first transistor. The second end of the third resistor is respectively connected to the first end of the fifth resistor and the first end of the coil;

[0016] The second end of the fourth resistor is respectively connected to the first end of the first capacitor and the first sampling port. The second end of the fifth resistor is respectively connected to the second end of the second capacitor and the second sampling port. The second end of the first capacitor and the second end of the second capacitor are grounded.

[0017] Optionally, the high-side sampling circuit includes a sixth resistor, a seventh resistor, and a third capacitor;

[0018] 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. The second end of the seventh resistor and the second end of the third capacitor are grounded.

[0019] Optionally, the low-side sampling circuit includes an eighth resistor, a ninth resistor, and a fourth capacitor;

[0020] 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. The second end of the ninth resistor and the second end of the fourth capacitor are grounded.

[0021] Optionally, the high-side switch includes a first NMOS transistor, and the low-side switch includes a second NMOS transistor.

[0022] According to a second aspect of the present invention, there is provided a diagnostic method for applying the vehicle fault diagnosis circuit described in the first aspect of the present invention, including:

[0023] 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;

[0024] If the auxiliary diagnostic power supply is in the off state, the high-side switch is in the off state, and the low-side switch is in the off state, determine that the fault type is high-side MOS breakdown or high-side short to power when the high-side voltage of the coil is greater than 2V;

[0025] 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, determine that the fault type is coil open or low-side MOS turn-on failure when the high-side voltage of the coil is greater than 9V and the low-side voltage of the coil is less than 2V;

[0026] 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, turn off the high-side switch and turn on the auxiliary diagnostic power supply. Determine that the fault type is high-side open or high-side drive failure when the high-side voltage of the coil is greater than 4V, and determine that the fault type is high-side short to ground when the high-side voltage of the coil is less than 2V;

[0027] 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, determine that the fault type is coil short circuit when the high-side voltage of the coil is less than 2V, and determine that the fault type is low-side MOS open failure when the high-side voltage of the coil is greater than 2V and the low-side voltage of the coil is greater than 2V;

[0028] 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, determine that the fault type is coil overcurrent when the difference between the two voltage values output by the coil loop current detection circuit is greater than the threshold.

[0029] According to a third aspect of the present invention, there is provided a diagnostic method for applying the vehicle fault diagnosis circuit described in the first aspect of the present invention, including:

[0030] 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;

[0031] 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, determine that the fault type is high-side MOS breakdown or high-side short circuit to the power supply; when the high-side voltage of the coil is less than 2V, determine that the fault type is high-side short circuit 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, determine that the fault type is coil open circuit fault or low-side MOS turn-on fault;

[0032] 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, determine that the fault type is 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, determine that the fault type is 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, determine that the fault type is coil overcurrent.

[0033] According to the fourth aspect of the present invention, a vehicle is provided, and the vehicle includes a vehicle fault diagnosis circuit according to the first aspect of the present invention.

[0034] The beneficial effects of the present invention are as follows: by setting an auxiliary diagnostic power supply circuit to control the on and off of the auxiliary diagnostic power supply, the present invention can not only achieve diagnosis but also control the current passing through the coil, so that the electromagnetic force is not sufficient to change the existing state of the solenoid valve, and thus the high-side safety switch can be not opened to detect the coil. At the same time, the diagnosis is controllable, avoiding increasing the static operating current. And when a short circuit fault occurs, the auxiliary diagnostic power supply can be turned off to improve safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic diagram of a vehicle fault diagnosis circuit in an embodiment of the present invention.

[0036] Figure 2 is a schematic diagram of a vehicle fault diagnosis circuit in an embodiment of the present invention.

[0037] Figure 3 is a flowchart of system power-on fault diagnosis in an embodiment of the present invention.

[0038] Figure 4 is a flowchart of idle time patrol fault diagnosis in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0039] Now, various exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention.

[0040] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way a limitation on the present invention, its application, or its use.

[0041] Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be regarded as part of the specification. In all the examples shown and discussed here, any specific values should be construed as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments may have different values.

[0042] It should be noted that like reference numerals and letters denote like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

[0043] In the description and claims of the present invention, features related to the terms "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is 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 an "or" relationship between the associated objects before and after.

[0044] As Figure 1 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.

[0045] 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 / off of the auxiliary diagnosis power supply.

[0046] 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 in the coil loop.

[0047] 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.

[0048] 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.

[0049] As Figure 2As shown, the high-side switch and the low-side switch are composed of NMOS transistors, and the driving is controlled by an ASIC chip. The high-side switch includes a first NMOS transistor DRVM1, and the first NMOS transistor DRVM1 is turned on or off by a 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, and the second NMOS transistor DRVM2 is turned on or off by a driving signal RCOIL_GATE2 to realize the opening or closing of the low-side switch.

[0050] 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 to power supply, high-side short to 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 to power supply, low-side short to ground, etc. The specific type of fault is determined according to 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.

[0051] In the present invention, by setting an auxiliary diagnostic power supply circuit to control the on / off of the auxiliary diagnostic power supply, it is possible to not only perform diagnosis but also control the current passing through the coil so that its electromagnetic force is not sufficient to change the existing state of the solenoid valve. Furthermore, it is possible to detect the coil without opening the high-side safety switch. At the same time, the diagnosis is controllable, avoiding an increase in the static operating current. And when a short-circuit fault occurs, the auxiliary diagnostic power supply can be turned off to improve safety.

[0052] As Figure 2 shown, in this embodiment, the auxiliary diagnostic power supply circuit 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-type transistor, and the second transistor Q1B is a PNP-type transistor.

[0053] The auxiliary diagnostic power supply VCC is respectively connected to the emitter of the second transistor Q1B and the first end of a 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 a second resistor R2. The second end of the second resistor R2 is connected to a control signal RCOIL_CTRL, and the control signal RCOIL_CTRL is used to control the on / off of the composite transistor.

[0054] The collector of the second transistor Q1B is respectively connected to the base and the emitter of the first transistor Q1A, and the collector of the first transistor Q1A is connected to the coil loop current detection circuit.

[0055] 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 diagnostic power supply.

[0056] As Figure 2 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.

[0057] The first end of the third resistor R3 is respectively connected to the first end of the fourth resistor R4 and the collector of the first transistor Q1A, and the second end of the third resistor R3 is respectively connected to the first end of the fifth resistor R5 and the first end of the coil.

[0058] The second end of the fourth resistor R4 is respectively connected to the first end of the first capacitor C1 and the first sampling port RCOIL_TEST1, the second end of the fifth resistor R5 is respectively connected to the second end of the second capacitor C2 and the second sampling port RCOIL_TEST2, and the second ends of the first capacitor C1 and the second capacitor C2 are grounded.

[0059] 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, and thus the current of the coil loop is calculated.

[0060] 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, and 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. The second end of the seventh resistor R7 and the second end of the third capacitor C3 are grounded.

[0061] As Figure 2 shown, the sixth resistor R6 samples the high-side voltage of the coil. The sixth resistor R6 and the seventh resistor form a voltage-dividing circuit to convert the high-side voltage of the coil into a voltage within the voltage range recognizable by the single-chip microcomputer. The third capacitor C3 is used to filter out interference.

[0062] 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, and 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. The second end of the ninth resistor R9 and the second end of the fourth capacitor C4 are grounded.

[0063] As Figure 2 shown, the eighth resistor R8 samples the low-side voltage of the coil. The eighth resistor R8 and the ninth resistor R9 form a voltage-dividing circuit to convert the low-side voltage of the coil into a voltage within the voltage range recognizable by the single-chip microcomputer. The fourth capacitor is used to filter out interference.

[0064] The present invention can achieve idle-time inspection and fault diagnosis when the system is powered on.

[0065] As Figure 3 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:

[0066] 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;

[0067] If the auxiliary diagnostic power supply is in the off state, the high-side switch is in the off state, and the low-side switch is in the off state, determine that the fault type is high-side MOS breakdown or high-side short to power when the high-side voltage of the coil is greater than 2V;

[0068] 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, determine that the fault type is coil open circuit or low-side MOS turn-on fault when the high-side voltage of the coil is greater than 9V and the low-side voltage of the coil is less than 2V;

[0069] 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, turn off the high-side switch and turn on the auxiliary diagnostic power supply. Determine that the fault type is high-side open circuit or high-side drive fault when the high-side voltage of the coil is greater than 4V, and determine that the fault type is high-side short to ground when the high-side voltage of the coil is less than 2V;

[0070] 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, determine that the fault type is coil short circuit when the high-side voltage of the coil is less than 2V, and determine that the fault type is low-side MOS open circuit fault when the high-side voltage of the coil is greater than 2V and the low-side voltage of the coil is greater than 2V;

[0071] 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, determine that the fault type is coil overcurrent when the difference between the two voltage values output by the coil loop current detection circuit is greater than the threshold.

[0072] RCOIL_CTRL OFF indicates that the auxiliary diagnostic power supply is in the off state, and RCOIL_CTRL ON indicates that the auxiliary diagnostic power supply is in the on state. RCOIL_GATE1 OFF indicates that the high-side switch is in the off state, and RCOIL_GATE1 ON indicates that the high-side switch is in the on state. RCOIL_GATE2 OFF indicates that the low-side switch is in the off state, and RCOIL_GATE2 ON indicates that the low-side switch is in the on state.

[0073] RCOIL_SUP_FBK is the coil high-side voltage collected by the high-side sampling circuit, FR_NC_FBK is the coil low-side voltage collected by the low-side sampling circuit, and RCOIL_TEST1 and RCOIL_TEST2 are two voltages collected by the coil loop current detection circuit.

[0074] As Figure 4 shown, this embodiment introduces a diagnostic method for a vehicle fault diagnosis circuit according to any embodiment of the present invention. It is a fault diagnosis during idle-time inspection, including:

[0075] 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;

[0076] 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, determine that the fault type is high-side MOS breakdown or high-side short to power when the coil high-side voltage is greater than 4V, determine that the fault type is high-side short to ground when the coil high-side voltage is less than 2V, and determine that the fault type is coil open circuit fault or low-side MOS turn-on fault when the coil high-side voltage is greater than 2V and less than 4V and the coil low-side voltage is less than 2V;

[0077] 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, determine that the fault type is coil short circuit when the coil high-side voltage is less than 2V, determine that the fault type is low-side MOS open circuit fault when the coil high-side voltage is greater than 2V and the coil low-side voltage is greater than 2V, and determine that the fault type is coil overcurrent when the coil high-side voltage is greater than 2V, the coil low-side voltage 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.

[0078] This embodiment introduces a vehicle, and the vehicle includes a vehicle fault diagnosis circuit according to any embodiment of the present invention.

[0079] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and not for limiting the scope of the present invention. Those skilled in the art should understand that the above embodiments can 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.

[0080] Those of ordinary skill in the art can realize that the modules and algorithm steps described in connection with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the present invention.

[0081] 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 foregoing method embodiments and will not be elaborated herein.

[0082] 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 merely illustrative. For example, the division of the modules is only a logical function division, and there can be other division methods in actual implementation. For example, 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 displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or modules can be in electrical, mechanical or other forms.

[0083] The modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, that is, they can be located in one place or distributed to multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of the embodiments of the present invention.

[0084] In addition, the various functional modules in the embodiments of the present invention can be integrated into one processing module, or each module can exist physically alone, or two or more modules can be integrated into one module.

[0085] When the above-mentioned 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, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods of various embodiments of the present invention. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical discs that can store program codes.

[0086] The above description is only a preferred embodiment of the present application and an explanation of the applied technical principles. 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 the specific combination of the above technical features, and 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 technical solution formed by mutually replacing the above features with the (but not limited to) technical features with similar functions disclosed in the present application.

[0087] It should be understood that the magnitudes of the sequence numbers of the steps in the present invention's content and embodiments do not absolutely mean the sequence of execution. The execution sequence of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention. For the purpose of illustration and description, the foregoing description of the implementation of the present disclosure has been given. The foregoing description is not exhaustive and does not intend to limit the present disclosure to the exact form disclosed. According to the above teachings, various deformations and modifications may exist, 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 applications, so that those skilled in the art can utilize the present disclosure in various embodiments and various modifications suitable for the specific purposes 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; 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.

2. A vehicle fault diagnosis circuit according to claim 1, characterized in that: The first transistor is an NPN transistor, and the second transistor is a PNP transistor.

3. A vehicle fault diagnosis circuit according to claim 1, 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.

4. 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.

5. 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.

6. 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.

7. A diagnostic method using a vehicle fault diagnostic circuit as claimed in any one of claims 1 to 6, 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.

8. A diagnostic method using a vehicle fault diagnostic circuit as claimed in any one of claims 1 to 6, 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.

9. A vehicle, characterized in that: The vehicle comprises a vehicle fault diagnosis circuit as described in any one of claims 1-6.

Images