A method and system for detecting the connection status of the output line of a DCDC module

Abstract

The present invention discloses a method and a system for detecting the connection state of the output circuit of a DCDC module. By combining the voltage method and the current method, it is convenient to diagnose the abnormal connection of the 12V output circuit of the DCDC module, and the instrument fault light can be lit in time to notify the customer to check and repair the vehicle in time to ensure vehicle safety. Implementing the present invention does not require changing the existing high-voltage and low-voltage power supply structure in a pure electric motor, and has the advantages of high detection accuracy, easy implementation, and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of DC converter diagnosis, and particularly to a method and system for detecting the connection state of the output line of a DCDC module. Background Art

[0002] In a pure electric vehicle, a DCDC module (DC converter) can convert the high-voltage electricity of a high-voltage battery into a 12V power supply and supply it to a low-voltage system to ensure the normal use of low-voltage electrical appliances and ECU controllers in the vehicle.

[0003] The DCDC module is installed on the vehicle. There may be abnormal connection of the negative wire harness terminal or the main fuse of the output circuit may be blown due to omission in production or after-sales replacement part installation, or vibration and bump of the vehicle during use. After the above situations occur, the 12V output by the DCDC module cannot be supplied to the low-voltage electrical appliances and ECU controllers in the vehicle, and only the power of the low-voltage battery can be consumed. When the consumption time increases, the low-voltage battery will be discharged, and its supply voltage will be less than the operable voltage range. When this situation occurs, the vehicle in motion will lose power due to the inoperability of the ECU controller, posing a very high risk to driving safety.

[0004] In the prior art, if a fault occurs inside the DCDC module (for example, input undervoltage, overcurrent, etc.), the DCDC module itself can diagnose the corresponding fault and directly light up the fault lamp on the combined instrument to remind the driver. However, if there is no fault inside the DCDC module, but a situation such as abnormal connection of the negative wire harness terminal occurs, the DCDC module cannot detect it by itself. To detect this situation, generally, an additional control circuit needs to be added inside the DCDC module in the prior art. By detecting the voltage signal of the corresponding resistor and inputting it to the input end of the control circuit, the control circuit judges the connection state between the DCDC module converter and the 12V battery according to the collected voltage data. Such a control circuit generally needs to use a control chip or a processing chip with data processing capabilities. Therefore, the existing detection method will increase the cost and development difficulty of the DCDC module and cannot be implemented for some DCDC modules without internal detection electronic components. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method and system for detecting the connection state of the output line of a DCDC module, which can conveniently detect and diagnose the abnormal connection state of the 12V circuit detected by the DCDC module and give an alarm reminder.

[0006] To solve the above technical problem, as one aspect of the present invention, a method for detecting the connection state of the output line of a DCDC module is provided. This method can be applied to a pure electric vehicle, and the method includes the following steps:

[0007] Step S10, when the triggering condition is satisfied, start the function of detecting the connection state of the output line of the DCDC module;

[0008] Step S11, periodically obtain the current output voltage value of the DCDC module and the positive voltage value of the current low-voltage battery in the electric vehicle;

[0009] Step S12, obtain the difference between the current output voltage value of the DCDC module and the positive voltage value of the current low-voltage battery in the electric vehicle, compare the difference with a predetermined voltage threshold, and determine whether the difference is greater than or equal to the voltage threshold;

[0010] Step S13, when the judgment result is yes, obtain the 12V output current value of the current DCDC module;

[0011] Step S14, determine whether the battery current value is less than a predetermined current threshold and lasts for at least a predetermined time threshold;

[0012] Step S15, when the judgment result is yes, determine that the 12V output line connection of the DCDC module is abnormal, perform an abnormal alarm, and limit the vehicle speed not to exceed a predetermined first vehicle speed threshold.

[0013] Wherein, in step S10, the triggering condition is:

[0014] The vehicle completes the low-voltage power-on and high-voltage power-on, and at the same time the vehicle speed is greater than a predetermined second vehicle speed threshold.

[0015] Wherein, the voltage threshold is 0.8V, the current threshold is 7A, the time threshold is 30s, the first vehicle speed threshold is 60km / h, and the second vehicle speed threshold is 3km / h.

[0016] Wherein, in step S15, the specific abnormal alarm is:

[0017] After determining that the 12V output line connection of the DCDC module is abnormal, light the warning light on the combined instrument or give an alarm by sound, and at the same time send a speed limit request to the VCU to control the vehicle speed not to exceed the predetermined first vehicle speed threshold.

[0018] Wherein, it further includes:

[0019] In step S12 or step S14, when the judgment result is no, determine that the 12V output line connection of the DCDC module is normal, and the process goes to step S11.

[0020] Correspondingly, on the other hand of the present invention, a system for detecting the connection state of the output line of the DCDC module is further provided. The system can be applied to pure electric vehicles and includes:

[0021] A function startup unit, configured to start the function of detecting the connection state of the output line of the DCDC module when it is determined that a predetermined trigger condition is met;

[0022] A voltage value acquisition unit, configured to periodically acquire the current output voltage value of the DCDC module and the positive voltage value of the current low-voltage battery in the electric vehicle;

[0023] A first condition judgment unit, configured to receive the current output voltage value of the DCDC module and the positive voltage value of the current low-voltage battery acquired by the voltage value acquisition unit, calculate the difference between the two, compare the difference with a predetermined voltage threshold, and judge whether the difference is greater than or equal to the voltage threshold;

[0024] A current value acquisition unit, configured to acquire the 12V output current value of the current DCDC module when the judgment result of the first condition judgment unit is yes;

[0025] A second condition judgment unit, configured to judge whether the battery current value is less than a predetermined current threshold and lasts for at least a predetermined time threshold;

[0026] An exception handling unit, configured to determine that the 12V output line connection of the DCDC module is abnormal, perform an exception alarm, and limit the vehicle speed not to exceed a predetermined first vehicle speed threshold when the judgment result of the second condition judgment unit is yes.

[0027] Wherein, the trigger condition is:

[0028] The vehicle completes the connection of the low-voltage power supply and the high-voltage power supply, and at the same time the vehicle speed is greater than a predetermined second vehicle speed threshold.

[0029] Wherein, the voltage threshold is 0.8V, the current threshold is 7A, the time threshold is 30s, the first vehicle speed threshold is 60km / h, and the second vehicle speed threshold is 3km / h.

[0030] Wherein, the exception handling unit is specifically configured to:

[0031] After determining that the 12V output line connection of the DCDC module is abnormal, light up the warning light on the combined instrument panel or give an alarm by sound, and at the same time send a speed limit request to the VCU to control the vehicle speed not to exceed a predetermined first vehicle speed threshold.

[0032] Wherein, it further includes:

[0033] A connection normal handling unit, configured to determine that the 12V output line connection of the DCDC module is normal and control the voltage value acquisition unit to continue working when the judgment result of the first condition judgment unit or the second condition judgment unit is no.

[0034] Implementing the embodiments of the present invention has the following beneficial effects:

[0035] The embodiments of the present invention provide a method and a system for detecting the connection state of the output line of a DCDC module. By comparing the 12V output voltage of the DCDC module with the positive voltage of the low-voltage battery and combining the output current of the DCDC module, the abnormal state of the connection of the output line of the DCDC module can be conveniently detected;

[0036] The embodiments of the present invention do not require an additional detection electronic component to form a monitoring circuit, but utilize the existing detection circuit. By combining the voltage method and the current method for comparison, the abnormal state of the connection state of the 12V output circuit of the DCDC module can be diagnosed; the method has low cost, and both the detection efficiency and the accuracy are very high; and after diagnosing the abnormality, the driver can be reminded to check and repair the vehicle in time by means of lighting the instrument fault lamp and limiting the maximum vehicle speed, improving the driving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, obtaining other drawings without creative efforts still belongs to the scope of the present invention.

[0038] Figure 1 It is a schematic diagram of the application environment of the present invention;

[0039] Figure 2 It is a schematic diagram of the main process of an embodiment of a method for detecting the connection state of the output line of a DCDC module provided by the present invention;

[0040] Figure 3 Corresponding to Figure 2 A more detailed flow diagram;

[0041] Figure 4 It is a schematic diagram of the structure of an embodiment of a system for detecting the connection state of the output line of a DCDC module provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

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

[0043] As Figure 1As shown in the figure, a schematic diagram of the application environment of the present invention is shown; in a pure electric vehicle, its power supply system generally includes a power battery and a battery management system, a vehicle controller, an integrated motor controller, a DCDC module, a low-voltage battery, and low-voltage loads. Among them:

[0044] The power battery and the battery management system are used to provide electrical energy for the pure electric vehicle to drive the vehicle. The power battery provides high-voltage power input to the DCDC module, and the DCDC module is used to convert the high-voltage power into 12V low-voltage power for output;

[0045] The vehicle controller is used to control the vehicle to apply high-voltage power, control the DCDC module to turn on and off, and monitor the fault status of the DCDC module;

[0046] The integrated motor controller is used for pre-charge protection when the DCDC module applies high-voltage power and for electrical energy discharge protection when the high-voltage power is removed;

[0047] The DCDC module, that is, the DC converter, is used to receive the instructions of the vehicle controller, convert the high-voltage power of the power battery into 12V low-voltage power, and output it for the low-voltage system to work;

[0048] The low-voltage battery, which can be a low-voltage lead-acid battery, for example, is used to supply power to the vehicle's 12V low-voltage system before the DCDC module works; or to supplement the power supply after the DCDC module supplies power;

[0049] The low-voltage loads include all the 12V low-voltage power-consuming systems on the vehicle, such as the controller ECU, the lighting system, the horn, the air-conditioning blower, the switches, and the motor, etc.

[0050] It can be understood that the low-voltage power supply system of a pure electric vehicle is jointly composed of a low-voltage battery and a DCDC module. When the vehicle does not apply high-voltage power and the DCDC module does not output power, the vehicle's low-voltage system is powered by the low-voltage battery. When the vehicle completes applying high-voltage power, the DCDC module starts to output power.

[0051] In order to ensure that the low-voltage battery is always at a relatively high state of charge and does not discharge. The magnitude of the power output by the DCDC module needs to be greater than the total power consumption of the vehicle's low-voltage loads. At the same time, it is also required that the output voltage of the DCDC module is higher than that of the low-voltage battery to ensure that the battery is in a continuous small-current charging state. Only when the vehicle instantaneously requires a large amount of power, exceeding the maximum power output capacity of the DCDC module, will the low-voltage battery supply power outward for a short time.

[0052] If a fault occurs inside the DCDC module, such as detected under-voltage input, over-current, etc., the DCDC module can diagnose the corresponding fault and directly light up the fault lamp on the combination instrument to remind the driver. However, if there is no fault inside the DCDC module, but the negative wire harness terminal connection is abnormal and the main fuse of the output circuit is blown. The power output by the DCDC module cannot be effectively transmitted to the low-voltage load, which will cause the low-voltage battery to continuously discharge externally, and then the phenomenon of power loss will occur.

[0053] The present invention provides a very efficient detection method for the fault caused by the connection state of the output circuit rather than a fault inside the DCDC module, which will be described below in conjunction with the accompanying drawings.

[0054] As Figure 2 shown, it shows a main flow schematic diagram of an embodiment of a method for detecting the connection state of the output line of the DCDC module provided by the present invention. In this embodiment, the method includes the following steps:

[0055] Step S10, when the trigger condition is satisfied, start the function of detecting the connection state of the output line of the DCDC module;

[0056] Among them, in step S10, the trigger condition is:

[0057] The vehicle completes powering on the low-voltage power supply and the high-voltage power supply, and at the same time the vehicle speed is greater than a predetermined second vehicle speed threshold. In one example, the second vehicle speed threshold is 3 km / h.

[0058] Step S11, periodically obtain the current output voltage value of the DCDC module and the positive voltage value of the current low-voltage battery in the electric vehicle;

[0059] Step S12, obtain the difference between the current output voltage value of the DCDC module and the positive voltage value of the current low-voltage battery in the electric vehicle (i.e., the KL30 voltage), compare the difference with a predetermined voltage threshold, and judge whether the difference is greater than or equal to the voltage threshold. In one example, the voltage threshold is 0.8 V;

[0060] Step S13, when the judgment result is yes, obtain the 12V output current value of the current DCDC module;

[0061] Step S14, judge whether the battery current value is less than a predetermined current threshold (such as 7 A) and lasts for at least a predetermined time threshold (such as 30 s);

[0062] Step S15, when the judgment result is yes, determine that the 12V output line connection of the DCDC module is abnormal, perform an abnormal alarm, and limit the vehicle speed not to exceed a predetermined first vehicle speed threshold (such as 60 km / h).

[0063] Among them, in the step S15, the specific operation of performing abnormal alarm is as follows:

[0064] After determining that the connection of the 12V output line of the DCDC module is abnormal, the warning light on the combination instrument is lit or an alarm is given through sound. At the same time, a speed limit request is sent to the VCU to control the vehicle speed not to exceed the predetermined first vehicle speed threshold. In this case, by lighting the fault lamp on the combination instrument through the DCDC module, the customer can be notified in advance to check and repair the vehicle in time. The VCU actively limits the maximum vehicle speed not to exceed 60 km / h according to the fault reported by the DCDC module, attracting the customer's attention to ensure vehicle safety.

[0065] Among them, it further includes:

[0066] In step S12 or step S14, when the judgment result is negative, it is determined that the connection of the 12V output line of the DCDC module is normal, and the process proceeds to step S11.

[0067] In the method of the present invention, the selection of the current threshold and the voltage threshold is based on the following principle:

[0068] Considering from the voltage aspect, the actual output voltage of the DCDC module is generally about 14V. And the maximum voltage of the storage battery is generally about 12.8V. When the DCDC module is not working, the KL30 voltage of the DCDC module is close to the voltage of the low-voltage storage battery. When the DCDC module is working normally and the output circuit is connected normally, the positive voltage value of the low-voltage storage battery (i.e., the KL30 voltage value) is close to the output voltage of the DCDC module. In this case, the difference between the detected 12V output value of the DCDC module and the KL30 voltage value is basically within 0.5V (harness loss). For example, in an example, when an abnormal connection occurs in the output circuit of the DCDC module, at this time, the detected 12V output voltage of the DCDC module is 14V, the KL30 voltage of the DCDC module is 12.8V, and the difference between the detected 12V output of the DCDC module and the KL30 voltage value is 1.2V. Thus, through voltage comparison and reserving a certain voltage acquisition error margin, when it is judged that the difference between the detected 12V output value of the DCDC module and the KL30 voltage value ≥ 0.8V, it can be judged that the connection state of the output circuit of the DCDC module is abnormal.

[0069] On the other hand, considering the current, as long as the vehicle is powered on with high voltage, there will be a certain power consumption of the vehicle's low-voltage load. This is the case even when the vehicle is in a very low-load condition. For example, the high-voltage relay will consume power, all the vehicle's ECU controllers will consume power, the instrument panel and the central control screen will also consume power, and so on. The total power consumption of the above-mentioned components will reach at least 10A. Therefore, when the DCDC module is working normally and the output circuit is connected properly, the low-voltage load is powered by the output power of the DCDC module. At this time, the DCDC module generally detects that the 12V output current will be ≥10A; however, if the output circuit connection of the DCDC module is abnormal, it is equivalent to that there is no load connected after the 12V output of the DCDC module, and the DCDC module generally detects that the 12V output current will be ≤1A (no output). In this way, by comparing with the current method and leaving a certain margin for current acquisition error, when it is judged that the 12V output current detected by the DCDC module is ≤7A and lasts for 30s, it can be determined that the output circuit connection state of the DCDC module is abnormal.

[0070] The method provided by the present invention combines the above voltage judgment method and current judgment method. When both methods judge a fault, the DCDC module can determine that the 12V circuit connection state is abnormal.

[0071] As Figure 2 shown, a more detailed flowchart corresponding to Figure 2 of the present invention is shown. The following steps are included in this process:

[0072] Step 1, determine whether the vehicle has completed powering on with low voltage;

[0073] Step 2, if the condition that the vehicle has completed powering on with low voltage is met, then continue to determine whether the vehicle has completed powering on with high voltage. If the vehicle has not completed powering on with low voltage, the DCDC module does not start the function of detecting the connection state of the 12V output terminal;

[0074] Step 3, if the condition that the vehicle has completed powering on with high voltage is met, the VCU enables the DCDC module to work and outputs 12V;

[0075] Step 4, determine whether the vehicle speed is ≥3 km / h;

[0076] Step 5, if the vehicle meets the condition that the vehicle speed is ≥3 km / h, the DCDC module starts the function of detecting the connection state of the 12V output terminal;

[0077] Step 6, determine whether the difference between the 12V output voltage detected by the DCDC module and the input voltage of the battery's constant power supply KL30 connected to itself is ≥0.8V;

[0078] Step 7, if the DCDC module meets the condition that the detected 12V output - KL30 voltage ≥ 0.8V, then continue to determine whether the detected 12V output current of the DCDC module ≤ 7A and lasts for 30s;

[0079] Step 8, if the condition that the detected 12V output - KL30 voltage of the DCDC module ≥ 0.8V and at the same time the detected 12V output current of the DCDC module ≤ 7A and lasts for 30s is met, then the DCDC module determines that the connection of the 12V output terminal is abnormal;

[0080] Step 9, the DCDC module lights up the combined instrument warning light;

[0081] Step 10, the VCU limits the vehicle speed ≤ 60 km / h;

[0082] Step 11, if the condition that the detected 12V output - KL30 voltage of the DCDC module ≥ 0.8V and at the same time the detected 12V output current of the DCDC module ≤ 7A and lasts for 30s is not met, then the DCDC module determines that the connection of the 12V output terminal is normal.

[0083] Step 12: For the whole vehicle use, the process goes back to the aforementioned Step 5, and the DCDC module maintains the function of starting to detect the connection state of the 12V output terminal;

[0084] As Figure 4 shown, a structural schematic diagram of an embodiment of a system for detecting the connection state of the output line of the DCDC module provided by the present invention is shown. In the implementation application, the system is implemented in the battery management system of a pure electric vehicle. Specifically, in this embodiment, the system 1 includes:

[0085] A function start unit 10, configured to start the function of detecting the connection state of the output line of the DCDC module when it is determined that a predetermined trigger condition is met;

[0086] A voltage value acquisition unit 11, configured to periodically acquire the current DCDC module output voltage value and the positive voltage value of the current low - voltage battery in the electric vehicle;

[0087] A first condition judgment unit 12, configured to receive the current DCDC module output voltage value and the positive voltage value of the current low - voltage battery obtained from the voltage value acquisition unit 11, calculate the difference between the two, compare the difference with a predetermined voltage threshold, and determine whether the difference is greater than or equal to the voltage threshold;

[0088] A current value acquisition unit 13, configured to acquire the 12V output current value of the current DCDC module when the judgment result of the first condition judgment unit 12 is yes;

[0089] The second condition judgment unit 14 is used to judge whether the battery current value is less than a predetermined current threshold and lasts for at least a predetermined time threshold;

[0090] The abnormal handling unit 15 is used to determine that the 12V output line of the DCDC module is abnormally connected when the judgment result of the second condition judgment unit 14 is yes, perform an abnormal alarm, and limit the vehicle speed not to exceed a predetermined first vehicle speed threshold; more specifically, after determining that the 12V output line of the DCDC module is abnormally connected, light the alarm lamp on the combined instrument or give an alarm by sound, and at the same time send a speed limit request to the VCU to control the vehicle speed not to exceed a predetermined first vehicle speed threshold.

[0091] The normal connection processing unit 16 is used to determine that the 12V output line of the DCDC module is normally connected when the judgment result of the first condition judgment unit 12 or the second condition judgment unit 14 is no, and control the voltage value acquisition unit to continue to work.

[0092] Specifically, in one example, the triggering condition is:

[0093] The vehicle completes powering on the low-voltage power supply and the high-voltage power supply, and at the same time the vehicle speed is greater than a predetermined second vehicle speed threshold.

[0094] Wherein, the voltage threshold is 0.8V, the current threshold is 7A, the time threshold is 30s, the first vehicle speed threshold is 60km / h, and the second vehicle speed threshold is 3km / h.

[0095] For more details, reference can be made to and combined with the content described above Figures 1 to 3 which will not be elaborated here.

[0096] Implementing the embodiments of the present invention has the following beneficial effects:

[0097] The embodiments of the present invention provide a method and system for detecting the connection state of the output line of the DCDC module. By comparing the 12V output voltage of the DCDC module with the positive voltage of the low-voltage battery and combining the output current of the DCDC module, the abnormal state of the connection of the output line of the DCDC module can be easily detected;

[0098] The embodiments of the present invention do not require an additional detection electronic component to form a monitoring circuit, but use the existing detection circuit. By combining the voltage method and the current method for comparison, the abnormal state of the connection state of the 12V output circuit of the DCDC module can be diagnosed; the method has low cost, and the detection efficiency and accuracy are very high; and after diagnosing the abnormality, it can remind the driver to check and repair the vehicle in time by lighting the instrument fault lamp and limiting the maximum vehicle speed, improving the driving safety.

[0099] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, apparatus, or computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) containing computer-usable program code.

[0100] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing device generate means for implementing the specified functions in Figure 1 one flow or multiple flows and / or blocks Figure 1 or means for implementing the specified functions in one block or multiple blocks.

[0101] The above-disclosed is only a preferred embodiment of the present invention, and of course, it cannot be used to limit the scope of the rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A method for detecting the connection state of the output line of a DCDC module, characterized in that, The method includes the following steps: Step S10, when a predetermined trigger condition is satisfied, start the function of detecting the connection state of the output line of the DCDC module; Step S11, periodically obtain the current output voltage value of the DCDC module and the positive voltage value of the current low-voltage battery in the electric vehicle; Step S12, obtain the difference between the current output voltage value of the DCDC module and the positive voltage value of the current low-voltage battery in the electric vehicle, compare the difference with a predetermined voltage threshold, and determine whether the difference is greater than or equal to the voltage threshold; Step S13, when the judgment result is yes, obtain the 12V output current value of the current DCDC module; Step S14, determine whether the current value is less than a predetermined current threshold and lasts for at least a predetermined time threshold; Step S15, if the difference between the current output voltage value of the DCDC module and the positive voltage value of the current low-voltage battery in the electric vehicle is greater than or equal to the voltage threshold, and the current value is less than a predetermined current threshold and lasts for at least a predetermined time threshold, determine that the 12V output line connection of the DCDC module is abnormal, perform an abnormal alarm, and limit the vehicle speed not to exceed a predetermined first vehicle speed threshold.

2. The method according to claim 1, wherein In step S10, the trigger condition is: The vehicle completes low-voltage power-on and high-voltage power-on, and at the same time the vehicle speed is greater than a predetermined second vehicle speed threshold.

3. The method according to claim 2, characterized in that The voltage threshold is 0.8V, the current threshold is 7A, the time threshold is 30s, the first vehicle speed threshold is 60 km / h, and the second vehicle speed threshold is 3 km / h.

4. The method according to claim 3, wherein In the step S15, the specific operation of the abnormal alarm is: After determining that the 12V output line connection of the DCDC module is abnormal, turn on the combined instrument alarm light or alarm by sound, and at the same time send a speed limit request to the VCU to control the vehicle speed not to exceed the predetermined first vehicle speed threshold.

5. The method according to any one of claims 1 to 4, characterized in that, Further include: In step S12 or step S14, when the judgment result is no, determine that the 12V output line connection of the DCDC module is normal, and the process goes to step S11.

6. A system for detecting the connection state of the output line of a DCDC module, characterized in that, Include: A function startup unit, used to start the function of detecting the connection state of the output line of the DCDC module when it is determined that a predetermined trigger condition is satisfied; A voltage value acquisition unit, used to periodically obtain the current output voltage value of the DCDC module and the positive voltage value of the current low-voltage battery in the electric vehicle; A first condition judgment unit, used to receive the current output voltage value of the DCDC module and the positive voltage value of the current low-voltage battery obtained by the voltage value acquisition unit, calculate the difference between the two, compare the difference with a predetermined voltage threshold, and determine whether the difference is greater than or equal to the voltage threshold; A current value acquisition unit, used to obtain the 12V output current value of the current DCDC module when the judgment result of the first condition judgment unit is yes; A second condition judgment unit, used to determine whether the current value is less than a predetermined current threshold and lasts for at least a predetermined time threshold; An abnormal handling unit, which is configured to determine that the connection of the 12V output line of the DCDC module is abnormal, perform an abnormal alarm, and limit the vehicle speed not to exceed a predetermined first vehicle speed threshold if the difference between the current output voltage value of the DCDC module and the positive voltage value of the current low-voltage battery in the electric vehicle is greater than or equal to the voltage threshold, and the current value is less than a predetermined current threshold and lasts for at least a predetermined time threshold.

7. The system according to claim 6, wherein The triggering condition is: The vehicle has completed powering on the low-voltage power supply and the high-voltage power supply, and at the same time the vehicle speed is greater than a predetermined second vehicle speed threshold.

8. The system according to claim 7, wherein The voltage threshold is 0.8V, the current threshold is 7A, the time threshold is 30s, the first vehicle speed threshold is 60 km / h, and the second vehicle speed threshold is 3 km / h.

9. The system according to claim 8, wherein Specifically, the abnormal handling unit is configured to: After determining that the connection of the 12V output line of the DCDC module is abnormal, turn on the alarm light on the combination instrument or give an alarm through sound, and at the same time send a speed limit request to the VCU to control the vehicle speed not to exceed the predetermined first vehicle speed threshold.

10. The system according to any one of claims 6 to 9, characterized in that, The system further includes: A normal connection handling unit, which is configured to determine that the connection of the 12V output line of the DCDC module is normal and control the voltage value acquisition unit to continue working when the judgment result of the first condition judgment unit or the second condition judgment unit is negative.

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