Load open-circuit fault diagnosis circuit and diagnosis method

Abstract

The invention discloses a load open-circuit fault diagnosis circuit and a diagnosis method. The circuit comprises a pulse generation circuit, an external load and a low-side detection circuit, the input end of the pulse generating circuit is connected with the pulse generator, the output end is connected with the high-side end, and the pulse generating circuit is used for receiving a pulse signal output by the pulse generator and transmitting the pulse signal to the high-side end; the external load is connected between the high side end and the low side end; the input end of the low-side detection circuit is connected with the low-side end, the output end of the low-side detection circuit is connected with the MCU detection end, and the low-side detection circuit is used for collecting electric signals of the low-side end and feeding back the electric signals to the MCU; and the MCU is used for receiving a feedback signal of the low-side detection circuit and judging an open circuit of the external load when the feedback signal is abnormal. Through cooperation of the pulse generation circuit, the low-side detection circuit and the MCU, accurate determination of an open-circuit fault of an external load is realized, the problem that disassembly and troubleshooting are needed in traditional detection is solved, and the vehicle load fault diagnosis requirement is met.

Description

Technical Field

[0001] This invention relates to the field of diagnostic circuit technology, and in particular to a load open-circuit fault diagnostic circuit and diagnostic method. Background Technology

[0002] In industries such as automotive electronics and industrial control, the connection reliability of loads (such as differential coils) directly affects the normal operation of equipment. Taking automotive differential coils as an example, they are installed in the vehicle chassis and are subjected to complex conditions such as bumps and vibrations over a long period of time. Loose connections between the coil connectors and the controller can easily occur, leading to differential lock failure and the vehicle becoming unable to escape, requiring assistance from a crane or tow truck. Current technologies lack efficient and accurate solutions for detecting open-circuit faults in such loads: traditional detection methods require lifting and disassembling the entire vehicle for inspection, which is cumbersome, time-consuming, and labor-intensive, and cannot monitor faults in real time while the vehicle is in motion; some simple detection circuits only judge faults by monitoring current changes, but they are prone to confusion between light load and open-circuit states, have weak anti-interference capabilities, and are prone to misjudgment. Furthermore, existing load control circuits do not integrate dedicated fault diagnosis modules, failing to provide timely feedback when faults occur, resulting in high difficulty in fault diagnosis and high maintenance costs. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a load open circuit fault diagnosis circuit, which, through the cooperation of a pulse generation circuit, a low-side detection circuit and an MCU, can accurately determine the external load open circuit fault.

[0004] The technical solution of the present invention: a load open circuit fault diagnosis circuit, including a pulse generation circuit, an external load and a low-side detection circuit; The input terminal of the pulse generation circuit is connected to the pulse generator, and the output terminal is connected to the high-side terminal. It is used to receive the pulse signal output by the pulse generator and transmit it to the high-side terminal. The external load is connected between the high side and the low side; The input terminal of the low-side detection circuit is connected to the low-side terminal, and the output terminal is connected to the MCU detection terminal. It is used to collect the electrical signal of the low-side terminal and feed it back to the MCU. The MCU is used to receive feedback signals from the low-side detection circuit and to determine that the external load is open when the feedback signal is abnormal.

[0005] The above technical solution involves receiving pulse signals from a pulse generator via a pulse generation circuit and transmitting them to the high-side terminal. An external load is connected between the high and low sides. The low-side detection circuit collects the low-side electrical signal and feeds it back to the MCU, converting the on / off state of the external load into changes in the low-side electrical signal. The MCU can directly identify open-circuit faults in the external load through abnormal electrical signal states, achieving hardware-based detection of open-circuit faults in the external load. Compared to purely software diagnostic methods, the detection results are more direct and reliable. This solves the problem of traditional testing requiring disassembly and troubleshooting, and is suitable for the fault diagnosis needs of automotive loads.

[0006] A further provision of the present invention includes a high-side self-test circuit, wherein the input terminal of the high-side self-test circuit is connected to the high-side terminal and the output terminal is connected to the MCU detection terminal, for acquiring the pulse signal of the high-side terminal and feeding it back to the MCU; the MCU is used to receive the feedback signal of the high-side self-test circuit and determine whether the pulse generation circuit is normal.

[0007] With the above further settings, the high-side self-test circuit collects the pulse signal from the high-side end and feeds it back to the MCU, so that the MCU can first confirm the working status of the pulse generation circuit and then determine whether the external load is open. This solves the problem that traditional diagnostics cannot distinguish between "pulse generation circuit fault" and "external load open circuit fault", and achieves accurate location of the fault source, avoiding misjudgment of the load as open circuit due to circuit fault itself.

[0008] A further embodiment of the present invention: the pulse generation circuit includes two transistors Q18, one transistor Q18 is connected to the high-side terminal, the other transistor Q18 is connected to the pulse generator, and the two transistors Q18 are interconnected.

[0009] With the above further configuration, the pulse generation circuit is built using two transistors Q18. One transistor Q18 is connected to the high-side terminal, and the other is connected to the pulse generator, and the two are interconnected. The dual transistors Q18 form a current amplification circuit, which utilizes the current amplification characteristics of the transistors to compensate for the insufficient drive capability of the MCU IO output. It can amplify the weak pulse signal output by the pulse generator, ensuring that the pulse signal can be stably and effectively transmitted to the high-side terminal, thus guaranteeing the reliability of the pulse detection signal transmission.

[0010] A further feature of the present invention is that a resistor R161 is connected in series between the high-side terminal and the transistor Q18 connected thereto.

[0011] With the above further configuration, resistor R161 is used as a current-limiting resistor to limit the current flowing through transistor Q18. When a short circuit fault occurs in the external wiring harness, it can prevent the transistor Q18 from being damaged by heat due to overcurrent. At the same time, it can prevent the short circuit current from impacting the pulse generator in reverse, thereby improving the short circuit resistance and working stability of the pulse generation circuit.

[0012] A further provision of the present invention: the low-side detection circuit includes a filter circuit and a voltage divider circuit. The filter circuit includes capacitors C97 and C96 and resistor R169. The voltage divider circuit includes resistors R166 and R167. The resistor R166 is connected to the low side, the resistor R167 is grounded, and the resistors R166 and R167 are connected in series to divide the voltage and then connected to the MCU detection terminal. The capacitor C97 is connected to the low side, the capacitor C96 is grounded, the capacitor C97 and the capacitor C96 are connected in series, and one end of the resistor R169 is connected to the resistor R166, and the other end is connected between the capacitor C96 and the ground.

[0013] With the above further configuration, the filter circuit performs RC filtering on the low-side signal to remove high-order harmonic noise from the low-side pulse signal. At the same time, it utilizes the electrostatic discharge protection characteristics of the capacitor to achieve electrostatic discharge protection at the port, ensuring the purity of the detection signal. The voltage divider circuit divides the low-side signal and connects it to the MCU detection terminal. It can divide the 12V low-side pulse signal to below 5V, which is compatible with the voltage tolerance range of the MCU detection terminal and prevents the MCU detection port from being damaged by overvoltage.

[0014] A further provision of the present invention: the low-side detection circuit further includes a capacitor C16 and a resistor R168, the resistor R168 being connected between the voltage divider circuit and the MCU detection terminal, and the capacitor C16 being connected between the voltage divider circuit and the resistor R168 and grounded.

[0015] With the above further settings, resistor R168 can limit the current flowing from the voltage divider circuit into the MCU detection terminal, preventing the MCU detection port from burning out due to excessive input current, thus achieving current limiting protection for the MCU detection port; capacitor C16 performs secondary filtering on the low-side detection signal after voltage division, further filtering out residual noise in the signal, avoiding erroneous detection results from the MCU due to noise interference, and improving the detection accuracy of the low-side detection signal.

[0016] A further provision of the present invention: the high-side self-test circuit includes a second filter circuit and a second voltage divider circuit. The second filter circuit includes capacitors C36 and C38 and resistor R85. The second voltage divider circuit includes resistors R83 and R86. The resistor R83 is connected to the high side, the resistor R86 is grounded, and the resistors R83 and R86 are connected in series to divide the voltage and then connected to the MCU detection terminal. The capacitor C36 is connected to the high side, the capacitor C38 is grounded, and the capacitors C36 and C38 are connected in series. One end of the resistor R85 is connected to the resistor R83, and the other end is connected between the capacitor C38 and the ground.

[0017] With the above further configuration, the second filter circuit can filter out noise in the high-side pulse signal, ensuring that the self-test signal fed back to the MCU is consistent with the actual output signal of the pulse generation circuit, providing a true basis for the MCU to judge the state of the pulse generation circuit; the second voltage divider circuit can reduce the voltage, thereby matching the voltage input requirements of the MCU detection terminal and avoiding overvoltage damage to the MCU detection port.

[0018] A further feature of the present invention is that the high-side self-test circuit also includes a capacitor C37 and a resistor R84. The resistor R84 is connected between the second voltage divider circuit and the MCU detection terminal, and the capacitor C37 is connected between the second voltage divider circuit and the resistor R84 and grounded.

[0019] With the above further settings, resistor R84 can limit the current flowing from the voltage divider circuit into the MCU detection terminal, providing current limiting protection for the MCU detection terminal and preventing damage to the MCU detection port due to excessive current; capacitor C37 performs secondary filtering on the high-side self-test signal after voltage division, eliminating residual noise in the signal, avoiding misjudgment of the high-side self-test signal by the MCU, and improving the accuracy of the MCU in judging faults in the pulse generation circuit.

[0020] Another objective of this invention is to provide a method for diagnosing load open-circuit faults.

[0021] The technical solution of the present invention: a method for diagnosing load open circuit faults, comprising the following steps: S1: The pulse generator continuously outputs detection pulses, which are transmitted to the high-side terminal via the pulse generation circuit. S2: The high-side self-test circuit acquires the pulse signal at the high-side end and feeds it back to the MCU; S3: The MCU determines the status of the high-side pulse feedback signal. If the feedback signal is normal, the pulse generation circuit is determined to be fault-free; if the feedback signal is abnormal, the pulse generation circuit is determined to be faulty. S4: The low-side detection circuit acquires the electrical signal at the low-side end and feeds it back to the MCU; S5: The MCU determines the status of the low-side feedback signal. If the feedback signal is normal, it determines that there is no open circuit fault in the external load; if the feedback signal is abnormal, it determines that the external load is open circuit.

[0022] By adopting the above technical solution, a step-by-step diagnostic process of "first detecting the pulse generation circuit and then detecting the external load" is used to achieve layered troubleshooting. This allows for the elimination of fault factors within the circuit itself before confirming the fault status of the external load, resulting in a more rigorous diagnostic logic. At the same time, relying on the real-time signal acquisition capability of the hardware circuit, fault judgment can be completed quickly. Compared with the pure software polling diagnostic method, the diagnostic efficiency is higher and the results are more accurate. Attached Figure Description

[0023] Figure 1This is a circuit diagram of a specific embodiment of the present invention. Detailed Implementation

[0024] The technical solutions in this embodiment will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] like Figure 1 As shown, the present invention provides a load open-circuit fault diagnosis circuit, including a pulse generation circuit, an external load and low-side detection circuit, and a high-side self-test circuit. The input terminal of the pulse generation circuit is connected to the pulse generator, and the output terminal is connected to the high-side terminal. It is used to receive the pulse signal output by the pulse generator and transmit it to the high-side terminal. The pulse generation circuit includes two transistors Q18, one transistor Q18 is connected to the high-side terminal, and the other transistor Q18 is connected to the pulse generator. The two transistors Q18 are interconnected. A resistor R161 is connected in series between the high-side terminal and the transistor Q18 connected thereto.

[0026] The external load is connected between the high side and the low side; The input terminal of the low-side detection circuit is connected to the low-side terminal, and the output terminal is connected to the MCU detection terminal. It is used to collect the electrical signal of the low-side terminal and feed it back to the MCU. The low-side detection circuit includes a filter circuit and a voltage divider circuit. The filter circuit includes capacitors C97 and C96 and resistor R169. The voltage divider circuit includes resistors R166 and R167. The resistor R166 is connected to the low side, the resistor R167 is grounded, and the resistors R166 and R167 are connected in series to divide the voltage and then connected to the MCU detection terminal. Capacitor C97 is connected to the low-side terminal, capacitor C96 is grounded, and capacitors C97 and C96 are connected in series. One end of resistor R169 is connected to resistor R166, and the other end is connected between capacitor C96 and ground. The low-side detection circuit also includes capacitor C16 and resistor R168. Resistor R168 is connected between voltage divider circuit one and the MCU detection terminal, and capacitor C16 is connected between voltage divider circuit one and resistor R168, and grounded.

[0027] The MCU is used to receive feedback signals from the low-side detection circuit and to determine that the external load is open when the feedback signal is abnormal. The input terminal of the high-side self-test circuit is connected to the high-side terminal, and the output terminal is connected to the MCU detection terminal. It is used to acquire the pulse signal from the high-side terminal and feed it back to the MCU. The MCU receives the feedback signal from the high-side self-test circuit and determines whether the pulse generation circuit is functioning correctly. The high-side self-test circuit includes a second filter circuit and a second voltage divider circuit. The second filter circuit includes capacitors C36 and C38 and resistor R85. The second voltage divider circuit includes resistors R83 and R86. The resistor R83 is connected to the high side, the resistor R86 is grounded, and the resistors R83 and R86 are connected in series to divide the voltage and then connected to the MCU detection terminal. Capacitor C36 is connected to the high-side terminal, capacitor C38 is grounded, and capacitors C36 and C38 are connected in series. One end of resistor R85 is connected to resistor R83, and the other end is connected between capacitor C38 and ground. The high-side self-test circuit also includes capacitor C37 and resistor R84. Resistor R84 is connected between voltage divider circuit two and the MCU detection terminal, and capacitor C37 is connected between voltage divider circuit two and resistor R84, and grounded.

[0028] The high-side terminal is used for high-side signal input, and the low-side terminal is used for low-side signal input.

[0029] (I) Working principle of pulse generation circuit The pulse signal output by the pulse generator is input to the transistor Q18 connected to it. After being transmitted through two interconnected transistors Q18, it is output to the high side. The resistor R161 connected in series between the high side and the corresponding transistor Q18 is used to limit the current flowing through the transistor Q18.

[0030] (II) Working principle of high-side self-test circuit The signal output from the high-side terminal is input to the high-side self-test circuit. It is first filtered by the second filter circuit composed of capacitors C36 and C38 and resistor R85, and then divided by the second voltage divider circuit composed of resistors R83 and R86. The divided signal is transmitted through resistor R84 and filtered by capacitor C37 before being input to the MCU detection terminal. The MCU determines whether the pulse generation circuit is normal by receiving the feedback signal from the high-side self-test circuit.

[0031] (III) Working principle of the low-side detection circuit The low-side signal is input to the low-side detection circuit. It is first filtered by a filter circuit consisting of capacitors C97 and C96 and resistor R169, and then divided by a voltage divider circuit consisting of resistors R166 and R167. The divided signal is transmitted through resistor R168 and filtered by capacitor C16 before being input to the MCU detection terminal. The MCU determines whether the external load is open-circuited by receiving the feedback signal from the low-side detection circuit.

[0032] The method for diagnosing open-circuit load faults includes the following steps: S1: The pulse generator continuously outputs detection pulses, which are transmitted to the high-side terminal via the pulse generation circuit. S2: The high-side self-test circuit acquires the pulse signal at the high-side end and feeds it back to the MCU; S3: The MCU determines the status of the high-side pulse feedback signal. If the feedback signal is normal, the pulse generation circuit is determined to be fault-free; if the feedback signal is abnormal, the pulse generation circuit is determined to be faulty. S4: The low-side detection circuit acquires the electrical signal at the low-side end and feeds it back to the MCU; S5: The MCU determines the status of the low-side feedback signal. If the feedback signal is normal, it determines that there is no open circuit fault in the external load; if the feedback signal is abnormal, it determines that the external load is open circuit.

Claims

1. A load open-circuit fault diagnosis circuit, characterized in that, Includes pulse generation circuit, external load and low-side detection circuit; The input terminal of the pulse generation circuit is connected to the pulse generator, and the output terminal is connected to the high-side terminal. It is used to receive the pulse signal output by the pulse generator and transmit it to the high-side terminal. The external load is connected between the high side and the low side; The input terminal of the low-side detection circuit is connected to the low-side terminal, and the output terminal is connected to the MCU detection terminal. It is used to collect the electrical signal of the low-side terminal and feed it back to the MCU. The MCU is used to receive feedback signals from the low-side detection circuit and to determine that the external load is open when the feedback signal is abnormal.

2. The load open-circuit fault diagnosis circuit according to claim 1, characterized in that, It also includes a high-side self-test circuit, whose input terminal is connected to the high-side terminal and whose output terminal is connected to the MCU detection terminal. The high-side self-test circuit is used to collect the pulse signal of the high-side terminal and feed it back to the MCU. The MCU is used to receive the feedback signal of the high-side self-test circuit and determine whether the pulse generation circuit is normal.

3. The load open-circuit fault diagnosis circuit according to claim 1, characterized in that, The pulse generation circuit includes two transistors Q18, one of which is connected to the high-side terminal and the other is connected to the pulse generator. The two transistors Q18 are interconnected.

4. The load open-circuit fault diagnosis circuit according to claim 3, characterized in that, A resistor R161 is connected in series between the high-side terminal and the transistor Q18 connected thereto.

5. The load open-circuit fault diagnosis circuit according to claim 1, characterized in that, The low-side detection circuit includes a filter circuit and a voltage divider circuit. The filter circuit includes capacitors C97 and C96 and resistor R169. The voltage divider circuit includes resistors R166 and R167. The resistor R166 is connected to the low side, the resistor R167 is grounded, and the resistors R166 and R167 are connected in series to divide the voltage and then connected to the MCU detection terminal. The capacitor C97 is connected to the low side, the capacitor C96 is grounded, the capacitor C97 and the capacitor C96 are connected in series, and one end of the resistor R169 is connected to the resistor R166, and the other end is connected between the capacitor C96 and the ground.

6. The load open-circuit fault diagnosis circuit according to claim 5, characterized in that, The low-side detection circuit also includes a capacitor C16 and a resistor R168. The resistor R168 is connected between the voltage divider circuit and the MCU detection terminal, and the capacitor C16 is connected between the voltage divider circuit and the resistor R168 and grounded.

7. The load open-circuit fault diagnosis circuit according to claim 2, characterized in that, The high-side self-test circuit includes a second filter circuit and a second voltage divider circuit. The second filter circuit includes capacitors C36 and C38 and resistor R85. The second voltage divider circuit includes resistors R83 and R86. The resistor R83 is connected to the high side, the resistor R86 is grounded, and the resistors R83 and R86 are connected in series to divide the voltage and then connected to the MCU detection terminal. The capacitor C36 is connected to the high side, the capacitor C38 is grounded, and the capacitors C36 and C38 are connected in series. One end of the resistor R85 is connected to the resistor R83, and the other end is connected between the capacitor C38 and the ground.

8. The load open-circuit fault diagnosis circuit according to claim 7, characterized in that, The high-side self-test circuit also includes a capacitor C37 and a resistor R84. The resistor R84 is connected between the second voltage divider circuit and the MCU detection terminal, and the capacitor C37 is connected between the second voltage divider circuit and the resistor R84 and grounded.

9. A method for diagnosing open-circuit faults in a load based on the circuit described in claims 1-8, characterized in that, Includes the following steps: S1: The pulse generator continuously outputs detection pulses, which are transmitted to the high-side terminal via the pulse generation circuit. S2: The high-side self-test circuit acquires the pulse signal at the high-side end and feeds it back to the MCU; S3: The MCU determines the status of the high-side pulse feedback signal. If the feedback signal is normal, it determines that the pulse generation circuit is fault-free. If the feedback signal is abnormal, the pulse generation circuit is determined to be faulty; S4: The low-side detection circuit acquires the electrical signal at the low-side end and feeds it back to the MCU; S5: The MCU determines the status of the low-side feedback signal. If the feedback signal is normal, it determines that there is no open circuit fault in the external load; if the feedback signal is abnormal, it determines that the external load is open circuit.

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