Blade electric vehicle DCDC reverse pre-charging fault diagnosis method

Abstract

The invention discloses a pure electric vehicle DCDC reverse pre-charging fault diagnosis method, which is mainly characterized in that abnormal states in a pre-charging preparation stage, a pre-charging starting stage and different pre-charging operation modes are accurately and orderly identified, and corresponding protection strategies are executed on different abnormal states in each reverse pre-charging link, so that the fault diagnosis of the reverse pre-charging fault of the pure electric vehicle is realized. Therefore, cascading failures are effectively and efficiently prevented, and abnormal condition diffusion is completely eradicated. Meanwhile, harm threats such as electric arc and short circuit caused by pre-charging failure of personnel and equipment can be obviously reduced; and the electrical system of the pure electric vehicle can be quickly and smoothly started through a stable pre-charging process and a perfect fault processing mechanism, so that the credibility of a user on a product is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of new energy vehicle electronics, and particularly to a method for diagnosing DCDC reverse pre-charging faults in pure electric vehicles. Background Art

[0002] With the popularization of electric vehicles, in-vehicle DCDC converters have become key components. Their main function is to convert high-voltage electricity (200 - 500V) into 12V low-voltage electricity to power low-voltage in-vehicle electronic devices (such as power steering, braking systems, multimedia, etc.). In recent years, bidirectional DCDC technology has gradually become a trend, which can not only support converting high-voltage direct current into low-voltage direct current, but also have a reverse pre-charging function. When powering on, the traditional pre-charging method is to use a pre-charging relay and a pre-charging resistor, and the pre-charging relay is controlled by the VCU for pre-charging; while DCDC reverse pre-charging uses the voltage of the battery to reverse charge the high-voltage bus capacitor through the multiplexed DCDC circuit. The benefits brought by this are: one is to cancel the pre-charging relay and the pre-charging resistor, saving cost and space; the other is that if a high-voltage fault occurs during the vehicle's driving process, the DCDC reverse pre-charging can also be used to temporarily supply high voltage to stop the vehicle and protect the safety of the driver.

[0003] In the existing field of pure electric vehicle technology, the technical route for in-vehicle DCDC reverse pre-charging is to set three stages of reverse pre-charging. 1. Soft start stage: The anti-reverse charging circuit operates in the PWM mode, and the duty cycle of the PWM signal increases sequentially to reduce the impact current; 2. Current limiting stage: The anti-reverse charging circuit operates in the PWM mode or the current limiting mode to limit the inductor current in the low-voltage switch circuit and perform forward pre-charging; 3. Boost stage: The anti-reverse charging circuit operates in the through mode to charge the capacitor measured by the high-voltage switch circuit.

[0004] The above technical route only prevents possible reverse charging faults, and cannot comprehensively diagnose various abnormal problems encountered during the DCDC reverse pre-charging process, and lacks targeted protection strategies for the occurred faults, making it difficult to ensure the personal safety of vehicle users as well as the safety of the whole vehicle and components. Summary of the Invention

[0005] In view of the above, the present invention aims to provide a method for diagnosing DCDC reverse pre-charging faults in pure electric vehicles to solve the problems that the current diagnosis of DCDC reverse pre-charging faults in pure electric vehicles is not comprehensive enough and the treatment measures are not perfect enough.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The present invention provides a method for diagnosing DCDC reverse pre-charging faults in pure electric vehicles, which includes:

[0008] Step S0: After the vehicle receives the power-on command, the DCDC enters the preparation stage;

[0009] Step S1: Detect whether the CAN communication is normal;

[0010] Step S2: After determining that the CAN communication is normal, detect whether the circuit temperature sensor is normal;

[0011] Step S3: After determining that the circuit temperature sensor is normal, detect whether the current sensor and voltage sensor in the loop are normal;

[0012] Step S4: After determining that both the current sensor and voltage sensor are normal, detect whether the battery voltage is greater than the minimum threshold required for pre-charging;

[0013] Step S5: After determining that the battery voltage is greater than the minimum threshold, the DCDC receives the working command and starts to execute the reverse pre-charging process;

[0014] Step S6: At the beginning stage of the DCDC reverse pre-charging, detect whether the circuits on the high-voltage side and low-voltage side of the DCDC are normally conducting;

[0015] Step S7: After determining that the circuit is conducting, detect whether the DCDC loop temperature is normal;

[0016] Step S8: After determining that the DCDC loop temperature is normal, perform mode-based fault detection according to different operating modes of the DCDC reverse pre-charging: detect whether the forward and flyback mode is normal, and after determining that the forward and flyback mode is normal, detect whether the flyback mode is normal; after determining that the flyback mode is normal, detect whether the push-pull mode is normal;

[0017] Step S9: After determining that the push-pull mode is normal, detect whether the voltage across the high-voltage bus capacitor meets the established expected value;

[0018] Step S10: After determining that the expected value is met, end the DCDC reverse pre-charging process;

[0019] Among them, if any of the detection results in Step S2, Step S3, Step S6, the forward and flyback mode, and the flyback mode is abnormal, or if it is detected in Step S4 that the battery voltage is less than the minimum threshold, then execute the first protection strategy;

[0020] If any of the detection results in Step S1, Step S7, and the push-pull mode is abnormal, or if it is detected in Step S9 that the voltage does not meet the expected value, then execute the second protection strategy.

[0021] In at least one possible implementation, the first protection strategy includes:

[0022] Stop the DCDC from working and feedback the fault information to the upper controller;

[0023] The upper controller notifies the user of the fault information;

[0024] And force the DCDC to enter the error state and wait to restart after the fault is recovered.

[0025] In at least one possible implementation manner, the second protection strategy includes:

[0026] Stop the DCDC from working and feedback the fault information to the upper controller;

[0027] The upper controller notifies the user of the fault information;

[0028] And force the DCDC to return to the ready state and wait to continue working after the fault is recovered.

[0029] In at least one possible implementation manner, detecting whether the forward and flyback mode is normal includes:

[0030] Detect whether the voltage of the main transformer of the circuit is within the normal range of the preset forward and flyback mode;

[0031] If so, detect whether the voltage of the secondary transformer of the circuit is within the normal range of the preset forward and flyback mode;

[0032] If so, start detecting the flyback mode.

[0033] In at least one possible implementation manner, detecting whether the flyback mode is normal includes:

[0034] Detect whether the voltage of the secondary transformer of the circuit is within the normal range of the preset flyback mode;

[0035] If so, start detecting the push-pull mode.

[0036] In at least one possible implementation manner, detecting whether the push-pull mode is normal includes:

[0037] Detect whether the voltage of the main transformer of the circuit is within the normal range of the preset push-pull mode.

[0038] In at least one possible implementation manner, the fault diagnosis method further includes:

[0039] Before the DCDC reverse pre-charge, continuously monitor the battery voltage signal through a voltage sensor;

[0040] When it is monitored that the battery voltage drops to the preset recharge threshold, automatically send a power-on command and first recharge the battery through the forward DCDC.

[0041] Compared with the prior art, the main design concept of the present invention lies in accurately and orderly identifying abnormal states in the pre-charging preparation stage, pre-charging start stage, and different pre-charging operation modes, such as CAN communication failure, over-temperature failure, current sensor failure, voltage sensor failure, battery power shortage, abnormal primary voltage of the main transformer, abnormal primary voltage of the secondary transformer, etc., and executing corresponding protection strategies for different abnormal states in each link, so as to effectively prevent cascading failures. For example, if pre-charging abnormalities are not diagnosed, it may cause subsequent circuits (such as inverters and motor controllers) to be damaged due to abnormal input voltage. The fault diagnosis proposed by the present invention can quickly isolate such problems and prevent the spread of faults; at the same time, it can also significantly reduce the threat of injuries such as electric arcs and short circuits caused by pre-charging failures to personnel and equipment; and the stable pre-charging process and perfect fault handling mechanism can ensure the fast and smooth start of the electrical system of electric vehicles, greatly enhancing user trust in the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described below with reference to the drawings, where:

[0043] Figure 1 is a schematic diagram of the main process of the DCDC reverse pre-charging fault diagnosis method for pure electric vehicles provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present invention and should not be construed as limiting the present invention.

[0045] The present invention proposes an embodiment of a DCDC reverse pre-charging fault diagnosis method for pure electric vehicles. Specifically, as Figure 1 shown, which includes:

[0046] Step S0: After the vehicle receives the power-on command, DCDC enters the preparation stage;

[0047] Step S1: Detect whether the CAN communication is normal;

[0048] Step S2: After determining that the CAN communication is normal, detect whether the circuit temperature sensor is normal;

[0049] Step S3: After determining that the circuit temperature sensor is normal, detect whether the current sensor and voltage sensor in the circuit are normal;

[0050] Step S4. After determining that both the current sensor and the voltage sensor are normal, detect whether the battery voltage is greater than a predetermined minimum threshold required for pre-charging;

[0051] Step S5. After determining that the battery voltage is greater than the minimum threshold, the DCDC receives a working instruction and starts to perform the reverse pre-charging process;

[0052] Step S6. At the beginning stage of the DCDC reverse pre-charging, detect whether the circuits on the high-voltage side and the low-voltage side of the DCDC are normally conducting;

[0053] Step S7. After determining that the circuit is conducting, detect whether the temperature of the DCDC loop is normal;

[0054] Step S8. After determining that the temperature of the DCDC loop is normal, perform sub-mode fault detection according to different operating modes of the DCDC reverse pre-charging: detect whether the forward and flyback mode is normal, and after determining that the forward and flyback mode is normal, detect whether the flyback mode is normal; after determining that the flyback mode is normal, detect whether the push-pull mode is normal;

[0055] Step S9. After determining that the push-pull mode is normal, detect whether the voltage across the high-voltage bus capacitor meets a predetermined expected value;

[0056] Step S10. After determining that the expected value is met, end the DCDC reverse pre-charging process;

[0057] In addition to the above DCDC reverse pre-charging process, for any abnormal detection result in step S2, step S3, step S6, the forward and flyback mode, or the flyback mode, or if the battery voltage is detected to be less than the minimum threshold in step S4, then execute the first protection strategy; and, if any abnormal detection result in step S1, step S7, or the push-pull mode, or if the voltage is detected not to meet the expected value in step S9, then execute the second protection strategy.

[0058] Regarding the first protection strategy, it may specifically include:

[0059] Stop the DCDC from working and feedback the fault information to the superior controller;

[0060] The superior controller notifies the user of the fault information;

[0061] And force the DCDC to enter an error state and wait to restart after the fault is recovered.

[0062] Regarding the second protection strategy, it may specifically include:

[0063] Stop the DCDC from working and feedback the fault information to the superior controller;

[0064] The superior controller notifies the user of the fault information;

[0065] And force the DCDC to return to the ready state and wait to continue working after the fault is recovered.

[0066] In addition, for the specific implementation process of the above-mentioned sub-mode detection, the following can be referred to:

[0067] (1) The detection of whether the forward and flyback modes are normal includes:

[0068] Detect whether the voltage of the main transformer (T1) of the detection circuit is within the normal range of the preset forward and flyback modes;

[0069] If so, detect whether the voltage of the secondary transformer (T2) of the detection circuit is within the normal range of the preset forward and flyback modes;

[0070] If so, start detecting the flyback mode.

[0071] (2) The detection of whether the flyback mode is normal includes:

[0072] Detect whether the voltage of the secondary transformer of the detection circuit is within the normal range of the preset flyback mode;

[0073] If so, start detecting the push-pull mode.

[0074] (3) The detection of whether the push-pull mode is normal includes:

[0075] Detect whether the voltage of the main transformer of the detection circuit is within the normal range preset for the push-pull mode.

[0076] Finally, it can also be supplemented and explained that in step S4 of the foregoing, if it is detected that the battery voltage is less than the minimum threshold, it indicates that a power-on failure problem occurs in the preparation stage. Therefore, it may be necessary to jump-start the battery. In view of this situation, in some other embodiments of the present invention, a supplementary power strategy is also provided to solve the above-mentioned power-on failure problem: before the DCDC reverse pre-charge, continuously monitor the battery voltage signal through a voltage sensor; when it is detected that the battery voltage drops to the preset supplementary power threshold, automatically send a power-on command, and first charge the battery through the forward DCDC to avoid affecting the subsequent reverse pre-charge process due to the detection of a power-on failure situation in the subsequent preparation stage.

[0077] In summary, the main design concept of the present invention lies in accurately and orderly identifying the pre-charging preparation stage, the pre-charging start stage, and abnormal states under different pre-charging operation modes, such as CAN communication failure, over-temperature failure, current sensor failure, voltage sensor failure, battery power shortage, abnormal primary side voltage of the main transformer, abnormal primary side voltage of the secondary transformer, etc. Corresponding protection strategies are executed for different abnormal states in each link, thereby effectively preventing cascading failures. For example, if the pre-charging abnormality is not diagnosed, it may cause subsequent circuits (such as inverters and motor controllers) to be damaged due to abnormal input voltage. The fault diagnosis proposed by the present invention can quickly isolate such problems and prevent the spread of faults; at the same time, it can also significantly reduce the threat of injuries such as electric arcs and short circuits caused by pre-charging failures to personnel and equipment; and the stable pre-charging process and perfect fault handling mechanism can ensure the rapid and smooth start of the electrical system of electric vehicles, greatly enhancing the user's trust in the product.

[0078] In the embodiments of the present invention, if terms expressing directions are mentioned, they are based on the relative concepts of the embodiments. In addition, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent the situation where A exists alone, A and B exist simultaneously, or B exists alone. Wherein A and B can be singular or plural. The character " / " generally represents an "or" relationship between the preceding and following associated objects. "At least one of the following" and its similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, and c can represent: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c can be single or multiple.

[0079] The structure, features, and effects of the present invention have been described in detail based on the embodiments shown in the drawings above. However, the above are only the preferred embodiments of the present invention. It should be noted that for the technical features involved in the above embodiments and their preferred modes, those skilled in the art can reasonably combine and match them into various equivalent solutions without departing from and without changing the design concept and technical effects of the present invention; therefore, the scope of the present invention is not limited by the drawings shown. As long as the changes made in accordance with the concept of the present invention or the equivalent embodiments modified into equivalent changes still do not exceed the spirit covered by the specification and the drawings, they should all be within the protection scope of the present invention.

Claims

1. A DCDC reverse pre-charge fault diagnosis method for pure electric vehicles, characterized in that, Including: Step S0: After the vehicle receives the power-on command, the DCDC enters the preparation stage; Step S1: Detect whether the CAN communication is normal; Step S2: After determining that the CAN communication is normal, detect whether the circuit temperature sensor is normal; Step S3: After determining that the circuit temperature sensor is normal, detect whether the current sensor and voltage sensor in the circuit are normal; Step S4: After determining that both the current sensor and voltage sensor are normal, detect whether the battery voltage is greater than the minimum threshold required for pre-charging; Step S5: After determining that the battery voltage is greater than the minimum threshold, the DCDC receives the working command and starts to execute the reverse pre-charging process; Step S6: At the beginning stage of the DCDC reverse pre-charging, detect whether the circuits on the high-voltage side and low-voltage side of the DCDC are normally conducting; Step S7: After determining that the circuit is conducting, detect whether the DCDC circuit temperature is normal; Step S8: After determining that the DCDC circuit temperature is normal, perform sub-mode fault detection according to different operating modes of the DCDC reverse pre-charging: Detect whether the forward and flyback mode is normal, and after determining that the forward and flyback mode is normal, detect whether the flyback mode is normal; after determining that the flyback mode is normal, detect whether the push-pull mode is normal; Step S9: After determining that the push-pull mode is normal, detect whether the voltage across the high-voltage bus capacitor meets the established expected value; Step S10: After determining that the expected value is met, end the DCDC reverse pre-charging process; Among them, if any of the detection results in Step S2, Step S3, Step S6, the forward and flyback mode, and the flyback mode is abnormal, or if it is detected in Step S4 that the battery voltage is less than the minimum threshold, then execute the first protection strategy; If any of the detection results in Step S1, Step S7, and the push-pull mode is abnormal, or if it is detected in Step S9 that the voltage does not meet the expected value, then execute the second protection strategy.

2. The method for diagnosing the DCDC reverse pre-charging fault of a pure electric vehicle according to claim 1, wherein The first protection strategy includes: Stop the DCDC from working and feedback the fault information to the superior controller; The superior controller notifies the user of the fault information; And force the DCDC to enter the error state and wait to restart after the fault is recovered.

3. The method for diagnosing the DCDC reverse pre-charging fault of a pure electric vehicle according to claim 1, wherein, The second protection strategy includes: Stop the DCDC from working and feedback the fault information to the superior controller; The superior controller notifies the user of the fault information; And force the DCDC to return to the preparation state and wait to continue working after the fault is recovered.

4. The method for diagnosing the DCDC reverse pre-charge fault of a pure electric vehicle according to claim 1, wherein The detection of whether the forward and flyback mode is normal includes: Detect whether the voltage of the main transformer in the circuit is within the normal range of the preset forward and flyback mode; If so, detect whether the voltage of the secondary transformer in the circuit is within the normal range of the preset forward and flyback mode; If so, start to detect the flyback mode.

5. The method for diagnosing the DCDC reverse pre-charging fault of a pure electric vehicle according to claim 1, characterized in that, The detection of whether the flyback mode is normal includes: Detect whether the voltage of the secondary transformer in the circuit is within the normal range of the preset flyback mode; If so, start to detect the push-pull mode.

6. The method for diagnosing the DCDC reverse pre-charge fault of a pure electric vehicle according to claim 1, wherein The detection of whether the push-pull mode is normal includes: Detect whether the voltage of the main transformer in the circuit is within the normal range preset for the push-pull mode.

7. The method for diagnosing the DCDC reverse pre-charging fault of a pure electric vehicle according to any one of claims 1 to 6, characterized in that, The fault diagnosis method further includes: Before the DCDC reverse pre-charging, continuously monitor the battery voltage signal through the voltage sensor; When it is detected that the battery voltage drops to the preset recharge threshold, an on-power instruction is automatically sent, and the battery is first recharged through the forward DCDC.

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