CN109738722B - Method for positioning electromagnetic interference source in vehicle based on CAN bus data - Google Patents
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Abstract
The invention provides a method for positioning an electromagnetic interference source in a vehicle based on CAN bus data, belonging to the technical field of vehicles and electromagnetic compatibility. The technical scheme is as follows: a method for positioning an electromagnetic interference source in a vehicle based on CAN bus data comprises the following steps: s1: data acquisition and analysis are carried out through CAN bus data acquisition equipment; s2: analyzing the electromagnetic compatibility of the nodes; analyzing the electromagnetic compatibility of the nodes; s3: analyzing the measurement data of the oscilloscope; s4: analyzing CAN faults according to the function or logic of the node with the error frame; s5: interference source and interference path analysis. The invention has the beneficial effects that: the invention CAN improve the efficiency of positioning the interference source and the interference path which generate interference on the CAN bus in the vehicle, shorten the time for positioning and analyzing the electromagnetic compatibility problem of the vehicle and ensure the accuracy of positioning the interference source.
Description
Technical Field
The invention relates to the technical field, in particular to a method for positioning an electromagnetic interference source in a vehicle based on CAN bus data.
Background
While the aspects of vehicle dynamic property, economy, comfort, safety, reduction of pollutant emission level and the like are improved, more and more electronic parts are applied to vehicles, so that the electromagnetic compatibility environment inside the vehicles is more and more complicated, particularly, high-voltage electronic parts up to hundreds of volts are mounted inside hybrid power vehicles, fuel cells and pure electric vehicles besides 12/24V low-voltage electronic parts, so that the electromagnetic environment of the vehicles is worse, and the high-voltage electronic parts generate serious electromagnetic interference on the low-voltage electronic parts, so that the low-voltage electronic parts cannot normally work.
When a vehicle encounters an electromagnetic compatibility problem, a part with the problem is generally sent to an electromagnetic compatibility laboratory of an automobile electronic part for testing, and then electromagnetic compatibility problem analysis and three-factor positioning are carried out according to tested data, so that the research and development period of the vehicle is prolonged, and the research and development cost is increased due to the expensive price of the electromagnetic compatibility laboratory test.
Disclosure of Invention
The invention aims to provide a method for positioning an electromagnetic interference source in a vehicle by using CAN bus data, which effectively reduces the working cost and shortens the working period by adopting conventional CAN bus data measuring equipment, an oscilloscope and a spectrum analyzer to carry out on-line measurement and analysis of the vehicle.
The invention is realized by the following measures: a method for positioning an electromagnetic interference source in a vehicle based on CAN bus data comprises the following steps:
the method comprises the following steps: the method comprises the steps that CAN bus data are adopted to position an electromagnetic interference source in a vehicle, data acquisition is carried out through CAN data acquisition equipment, if the node is not lost due to excessive error frames and the node is allowed to automatically stop sending data under the condition that the node meets the condition, whether the condition is met or not is judged, if the condition is met, CAN fault analysis is carried out through functions or logics of the vehicle and the node, and if not, electromagnetic compatibility analysis is required; if the node is not allowed to stop sending data and the node is lost, performing electromagnetic compatibility analysis; if the node is lost due to error frames or excessive error frames, analyzing whether the node is caused by electromagnetic interference or not through oscilloscope measurement data of the CAN bus, if so, analyzing an interference source and an interference path, and otherwise, analyzing CAN faults through functions or logics of a vehicle and the node;
step two: the CAN data acquisition equipment is accessed to a vehicle CAN network, nodes on the CAN network are awakened and data are checked, and CAN communication faults caused by inconsistent baud rates, poor connection of CAN physical wiring harnesses, lack of matching resistors and the like are eliminated;
step three: under the condition of normal operation of a vehicle, a CAN node has excessive non-error frames, and the CAN node is suddenly lost under the condition that the node does not allow data transmission stop under the normal working condition, the electromagnetic compatibility of the node needs to be analyzed, an rectification scheme is formulated according to the analysis result, if the node is lost when the working state of the node changes, the electromagnetic compatibility of the node is mainly analyzed, the electromagnetic compatibility of the node is analyzed under the conditions that a control board is connected with the physical layout position and the ground of an internal interference source, whether an I/O port of an MCU is interfered, whether a cable with interference is near the MCU and the like, and the analysis result is verified by a spectrum analyzer and a near probe; otherwise, mainly analyzing the electromagnetic compatibility characteristics of the environment where the node is located, determining possible interference source parts according to the change of the working state of the vehicle before and after the node is lost, analyzing the electrical characteristics of the potential interference source parts, the connection mode with the lost node and the physical distance between the lost node and a wire harness of the lost node, gradually confirming the analysis result through a spectrum analyzer and a near-field probe to determine a main interference source, and analyzing the characteristics and the interference path of an interference signal through the data of the spectrum analyzer and the data change rule;
step four: under the condition of normal operation of a vehicle, when one or more nodes are lost due to error frames or even excessive error frames of a CAN bus, the quality of CAN network signals needs to be analyzed; if the error frame sent by a certain node is too much and other nodes are lost, analyzing the function or logic fault of the sending node; otherwise the network determines that it is subject to electromagnetic interference; connecting CAN _ H (high level transmission line), CAN ground (CAN bus reference grounding point), CAN _ L (low level transmission line), and CAN ground to oscilloscope via differential probe respectively to measure VCAN_H(CAN _ H voltage to CAN ground) and VCAN_L(voltage of CAN _ L to CAN ground), and obtaining differential voltage V by channel subtraction calculation of oscilloscope or measurement of another path of differential probediff＝VCAN_H-VCAN_LRespectively define VdiffAt bit time tBTime T of sampling pointB_sampling∈[tB×75％,tB×82％]Voltage V ofdiff_samplingThe minimum voltage of a recessive bit required by the CAN bus network is Vdiff_r_minThe maximum voltage of the recessive bit required by the CAN bus network is Vdiff_r_maxThe CAN bus network requires a dominant bit minimum voltage ofVdiff_d_minThe maximum voltage of dominant bit required by CAN bus network is Vdiff_d_maxIf the bus is in the recessive state Vdiff_sampling∈(Vdiff_r_min,Vdiff_r_max) The time-simultaneous bus is in dominant state Vdiff_sampling∈(Vdiff_d_min,Vdiff_d_max) The bus data is normal, otherwise the CAN bus network is subjected to electromagnetic interference;
step five: analysis VCAN_HAnd VCAN_LData for locating the time interval T between two adjacent peaks with consistent voltage fluctuationinterference_nThen the interference source frequency is respectively
Where interference _ n is the interference source 1.. n, the same analysis VdiffEach interference source frequency causing bus data to be interfered is the interference source frequency causing bus fault, and the rest are potential interference source frequencies;
step six: according to the frequency of each interference source, the frequency of a switching circuit of each vehicle-mounted part and a measuring signal of a frequency spectrograph, each interference source is confirmed by adopting an elimination method such as stopping working and cutting off a power supply, and an interference path is confirmed according to the connection mode of each interference source and a vehicle frame, the physical distance between a wire harness of each interference source and a CAN bus and the like.
In order to better achieve the above object, the present invention provides a method for positioning an electromagnetic interference source in a vehicle based on CAN bus data, comprising the following steps:
s1: data acquisition and analysis are carried out through CAN bus data acquisition equipment;
s2: analyzing the electromagnetic compatibility of the lost node;
s3: analyzing the measurement data of the oscilloscope;
s4: analyzing CAN faults according to the function or logic of the node with the error frame;
s5: interference source and interference path analysis.
In step S1, the specific steps of data acquisition and analysis by the CAN bus data acquisition device are as follows:
(1) the CAN bus data acquisition equipment acquires CAN network data and eliminates CAN bus faults caused by inconsistent baud rate of each node, poor connection of wire harnesses and uncomfortable matching resistance;
(2) if the node fails to send data due to excessive non-error frames and no condition exists, executing step S2, if the node fails to send data due to excessive non-error frames and one or more conditions are met, executing step S4;
(3) if there are error frames or the number of error frames is too many to cause the node to be lost, step S3 is executed.
In step S2, the specific steps of analyzing the electromagnetic compatibility of the lost node are as follows:
(1) if the working state of the node changes, the voltage change rate of the high-voltage circuit is greater than 1 millisecond per volt or the current change rate is greater than 1 millisecond per ampere, the high-voltage circuit interferes with the low-voltage circuit, so that the low-voltage circuit cannot normally operate, and the node is lost, and whether the main control board circuit is interfered or not is mainly analyzed; otherwise, the present step S2 is executed;
(2) analyzing the working state of the vehicle before and after the node is lost;
(3) before and after the working state of the vehicle changes, other parts of the high-voltage circuit, the voltage change rate of which is more than 1 millisecond per volt or the current change rate of which is more than 1 millisecond per ampere, are defined as electronic parts which interfere with the node;
(4) analyzing the circuit interference frequency of all electronic parts with interference at the moment of node loss by using an oscilloscope, measuring a signal with completely consistent waveform for multiple times continuously by using the oscilloscope, namely a periodic interference signal, reading the interval time between adjacent periodic signals, and taking the reciprocal of the interval time to obtain the interference frequency of the circuit;
(5) checking whether all electronic parts which can be interference sources are directly connected with the node through the connector or the wiring harnesses of the electronic parts are directly bundled together with the wiring harness of the node, and taking the parts with the phenomena as key analysis objects;
(6) the electronic parts which become interference sources are checked through an elimination method by using a spectrum analyzer and a near-field probe, and the interference sources are determined;
(7) and confirming an interference path according to the checked result and combining the data of the spectrum analyzer.
In step S3, the electromagnetic compatibility analysis of the lost node includes the specific steps of:
(1) respectively measuring voltage signals of CAN _ H to CAN ground and CAN _ L to CAN ground to determine whether CAN _ H and CAN _ L signal lines are interfered, if the measurement result conforms to the standard ISO11898-1-2003 road vehicle-controller area network-data link layer and physical signals, the CAN bus is not interfered, and the step S3 is finished; otherwise, continuing to execute step S3;
(2) observing periodic interference signals appearing on the CAN _ H and the CAN _ L, measuring and reading interval time between adjacent periodic signals through an oscilloscope, and taking the reciprocal of the interval time to determine the interference frequency of the interval time;
(3) analyzing aperiodic interference signals appearing on the CAN _ H and the CAN _ L according to the working state of the vehicle, and confirming the electronic parts generating interference;
(4) calculating a difference signal Vdiff＝VCAN_H-VCAN_L(ii) a If ringing during the explicit/implicit level conversion causes the bit sampling point to exceed the normal range, adjusting the matching resistance;
(5) through differential data analysis, interference sources influencing the signal quality of differential data are determined as interference sources which generate interference on CAN network data, and other interference sources are potential interference sources.
In step S4, the specific steps of performing CAN fault analysis according to the function or logic of the node where the error frame occurs are as follows:
(1) the node is pulled out from the CAN network, and CAN physical level signals of the node are independently measured and analyzed;
(2) and collecting message data and analyzing whether the CAN sending program of the node is abnormal or not.
In step S5, the specific steps of determining the frequency of the interference source according to the periodic interference signal are as follows:
(1) determining the frequency of an interference source according to the periodic interference signal;
(2) determining a sudden interference source according to the working state of the vehicle;
(3) analyzing by referring to the electromagnetic compatibility test report of each electronic part according to the results of the step (1) and the step (2) to determine a possible interference source;
(4) distinguishing potential interference sources and interference sources which have influence on CAN data through the measured or calculated differential level;
(5) and analyzing and determining an interference path by combining data of a spectrum analyzer according to the electronic parts generating interference, the physical connection mode and the physical distance between the wire harness and the CAN bus wire harness.
The invention has the beneficial effects that: the invention provides a method for positioning an electromagnetic interference source in a vehicle based on CAN bus data, which analyzes and positions the electromagnetic interference source and an interference path of the vehicle according to the data of CAN bus data measuring equipment, an oscilloscope and a spectrum analyzer by effectively combining the data of the CAN bus data measuring equipment, the oscilloscope and the spectrum analyzer, thereby effectively improving the analysis efficiency of the electromagnetic compatibility problem of the vehicle and ensuring the accuracy of the interference source and the interference path to the maximum extent; the method effectively improves the efficiency of positioning the interference source and the interference path which generate interference on the CAN bus in the vehicle, shortens the time for positioning and analyzing the electromagnetic compatibility problem of the vehicle, ensures the accuracy of positioning the interference source, and is also suitable for the electromagnetic compatibility correction and analysis of the vehicle for notice test.
Drawings
FIG. 1 is an overall flow chart illustrating the analysis of electromagnetic interference sources and interference paths in a vehicle via CAN data in accordance with the present invention.
FIG. 2 is a schematic diagram of the data measurement connection of the oscilloscope of the present invention.
FIG. 3 is a flow chart of data analysis of an oscilloscope according to the present invention.
FIG. 4 is a flowchart of the missing node electromagnetic compatibility performance analysis of the present invention.
Fig. 5 is a flow chart of the interference source and interference path analysis of the present invention.
Detailed Description
In order to clearly illustrate the technical features of the present solution, the present solution is explained below by way of specific embodiments.
Referring to fig. 1 to 5, the present invention is: a method for positioning an electromagnetic interference source in a vehicle based on CAN bus data comprises the following steps:
the method comprises the following steps: the method comprises the steps that CAN bus data are adopted to position an electromagnetic interference source in a vehicle, data acquisition is carried out through CAN data acquisition equipment, if the node is not lost due to excessive error frames and the node is allowed to automatically stop sending data under the condition that the node meets the condition, whether the condition is met or not is judged, if the condition is met, CAN fault analysis is carried out through functions or logics of the vehicle and the node, and if not, electromagnetic compatibility analysis is required; if the node is not allowed to stop sending data and the node is lost, performing electromagnetic compatibility analysis; if the node is lost due to error frames or excessive error frames, analyzing whether the node is caused by electromagnetic interference or not through oscilloscope measurement data of the CAN bus, if so, analyzing an interference source and an interference path, and otherwise, analyzing CAN faults through functions or logics of a vehicle and the node;
step two: the CAN data acquisition equipment is accessed to a vehicle CAN network, nodes on the CAN network are awakened and data are checked, and CAN communication faults caused by inconsistent baud rates, poor connection of CAN physical wiring harnesses, lack of matching resistors and the like are eliminated;
step three: under the condition of normal operation of a vehicle, a CAN node has excessive non-error frames, and the CAN node is suddenly lost under the condition that the node does not allow data transmission stop under the normal working condition, the electromagnetic compatibility of the node needs to be analyzed, an rectification scheme is formulated according to the analysis result, if the node is lost when the working state of the node changes, the electromagnetic compatibility of the node is mainly analyzed, the electromagnetic compatibility of the node is analyzed under the conditions that a control board is connected with the physical layout position and the ground of an internal interference source, whether an I/O port of an MCU is interfered, whether a cable with interference is near the MCU and the like, and the analysis result is verified by a spectrum analyzer and a near probe; otherwise, mainly analyzing the electromagnetic compatibility characteristics of the environment where the node is located, determining possible interference source parts according to the change of the working state of the vehicle before and after the node is lost, analyzing the electrical characteristics of the potential interference source parts, the connection mode with the lost node and the physical distance between the lost node and a wire harness of the lost node, gradually confirming the analysis result through a spectrum analyzer and a near-field probe to determine a main interference source, and analyzing the characteristics and the interference path of an interference signal through the data of the spectrum analyzer and the data change rule;
step four: under the condition of normal operation of a vehicle, when one or more nodes are lost due to error frames or even excessive error frames of a CAN bus, the quality of CAN network signals needs to be analyzed; if the error frame sent by a certain node is too much and other nodes are lost, analyzing the function or logic fault of the sending node; otherwise the network determines that it is subject to electromagnetic interference; connecting CAN _ H (high level transmission line), CAN ground (CAN bus reference grounding point), CAN _ L (low level transmission line), and CAN ground to oscilloscope via differential probe respectively to measure VCAN_H(CAN _ H voltage to CAN ground) and VCAN_L(voltage of CAN _ L to CAN ground), and obtaining differential voltage V by channel subtraction calculation of oscilloscope or measurement of another path of differential probediff＝VCAN_H-VCAN_LRespectively define VdiffAt bit time tBTime T of sampling pointB_sampling∈[tB×75％,tB×82％]Voltage V ofdiff_samplingThe minimum voltage of a recessive bit required by the CAN bus network is Vdiff_r_minThe maximum voltage of the recessive bit required by the CAN bus network is Vdiff_r_maxThe minimum voltage of dominant bit required by CAN bus network is Vdiff_d_minThe maximum voltage of dominant bit required by CAN bus network is Vdiff_d_maxIf the bus is in the recessive state Vdiff_sampling∈(Vdiff_r_min,Vdiff_r_max) The time-simultaneous bus is in dominant state Vdiff_sampling∈(Vdiff_d_min,Vdiff_d_max) The bus data is normal, otherwise the CAN bus network is subjected to electromagnetic interference;
step five: analysis VCAN_HAnd VCAN_LData for locating the time interval T between two adjacent peaks with consistent voltage fluctuationinterference_nThen the interference source frequency is respectively
Where interference _ n is the interference source 1.. n, the same analysis VdiffEach interference source frequency causing bus data to be interfered is the interference source frequency causing bus fault, and the rest are potential interference source frequencies;
step six: according to the frequency of each interference source, the frequency of a switching circuit of each vehicle-mounted part and a measuring signal of a frequency spectrograph, each interference source is confirmed by adopting an elimination method such as stopping working and cutting off a power supply, and an interference path is confirmed according to the connection mode of each interference source and a vehicle frame, the physical distance between a wire harness of each interference source and a CAN bus and the like.
In order to better achieve the above object, the present invention provides a method for positioning an electromagnetic interference source in a vehicle based on CAN bus data, comprising the following steps:
s1: data acquisition and analysis are carried out through CAN bus data acquisition equipment;
s2: analyzing the electromagnetic compatibility of the lost node;
s3: analyzing the measurement data of the oscilloscope;
s4: analyzing CAN faults according to the function or logic of the node with the error frame;
s5: interference source and interference path analysis.
In step S1, the specific steps of data acquisition and analysis by the CAN bus data acquisition device are as follows:
(1) the CAN bus data acquisition equipment acquires CAN network data and eliminates CAN bus faults caused by inconsistent baud rate of each node, poor connection of wire harnesses and uncomfortable matching resistance;
(2) if the node fails to send data due to excessive non-error frames and no condition exists, executing step S2, if the node fails to send data due to excessive non-error frames and one or more conditions are met, executing step S4;
(3) if there are error frames or the number of error frames is too many to cause the node to be lost, step S3 is executed.
In step S2, the steps of analyzing the electromagnetic compatibility of the lost node are as follows:
(1) if the working state of the node changes, the voltage change rate of the high-voltage circuit is greater than 1 millisecond per volt or the current change rate is greater than 1 millisecond per ampere, the high-voltage circuit interferes with the low-voltage circuit, so that the low-voltage circuit cannot normally operate, and the node is lost, and whether the main control board circuit is interfered or not is mainly analyzed; otherwise, the present step S2 is executed;
(2) analyzing the working state of the vehicle before and after the node is lost;
(3) before and after the working state of the vehicle changes, other parts of the high-voltage circuit, the voltage change rate of which is more than 1 millisecond per volt or the current change rate of which is more than 1 millisecond per ampere, are defined as electronic parts which interfere with the node;
(4) analyzing the circuit interference frequency of all electronic parts with interference at the moment of node loss by using an oscilloscope, measuring a signal with completely consistent waveform for multiple times continuously by using the oscilloscope, namely a periodic interference signal, reading the interval time between adjacent periodic signals, and taking the reciprocal of the interval time to obtain the interference frequency of the circuit;
(5) checking whether all electronic parts which can be interference sources are directly connected with the node through the connector or the wiring harnesses of the electronic parts are directly bundled together with the wiring harness of the node, and taking the parts with the phenomena as key analysis objects;
(6) the electronic parts which become interference sources are checked through an elimination method by using a spectrum analyzer and a near-field probe, and the interference sources are determined;
(7) and confirming an interference path according to the checked result and combining the data of the spectrum analyzer.
In step S3, the electromagnetic compatibility analysis of the lost node includes the specific steps of:
(1) respectively measuring voltage signals of CAN _ H to CAN ground and CAN _ L to CAN ground to determine whether CAN _ H and CAN _ L signal lines are interfered, if the measurement result conforms to the standard ISO11898-1-2003 road vehicle-controller area network-data link layer and physical signals, the CAN bus is not interfered, and the step S3 is finished; otherwise, continuing to execute step S3;
(2) observing periodic interference signals appearing on the CAN _ H and the CAN _ L, measuring and reading interval time between adjacent periodic signals through an oscilloscope, and taking the reciprocal of the interval time to determine the interference frequency of the interval time;
(3) analyzing aperiodic interference signals appearing on the CAN _ H and the CAN _ L according to the working state of the vehicle, and confirming the electronic parts generating interference;
(4) calculating a difference signal Vdiff＝VCAN_H-VCAN_L(ii) a If ringing during the explicit/implicit level conversion causes the bit sampling point to exceed the normal range, adjusting the matching resistance;
(5) through differential data analysis, interference sources influencing the signal quality of differential data are determined as interference sources which generate interference on CAN network data, and other interference sources are potential interference sources.
In step S4, the specific steps of performing CAN fault analysis according to the function or logic of the node where the error frame occurs are as follows:
(1) the node is pulled out from the CAN network, and CAN physical level signals of the node are independently measured and analyzed;
(2) and collecting message data and analyzing whether the CAN sending program of the node is abnormal or not.
In step S5, the specific steps of determining the frequency of the interference source according to the periodic interference signal are as follows:
(1) determining the frequency of an interference source according to the periodic interference signal;
(2) determining a sudden interference source according to the working state of the vehicle;
(3) analyzing by referring to the electromagnetic compatibility test report of each electronic part according to the results of the step (1) and the step (2) to determine a possible interference source;
(4) distinguishing potential interference sources and interference sources which have influence on CAN data through the measured or calculated differential level;
(5) and analyzing and determining an interference path by combining data of a spectrum analyzer according to the electronic parts generating interference, the physical connection mode and the physical distance between the wire harness and the CAN bus wire harness.
The technical features of the present invention which are not described in the above embodiments may be implemented by or using the prior art, and are not described herein again, of course, the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and variations, modifications, additions or substitutions which may be made by those skilled in the art within the spirit and scope of the present invention should also fall within the protection scope of the present invention.
Claims (4)
1. A method for positioning an electromagnetic interference source in a vehicle based on CAN bus data is characterized by comprising the following steps:
s1: data acquisition and analysis are carried out through CAN bus data acquisition equipment;
s2: analyzing the electromagnetic compatibility of the lost node;
s3: analyzing the measurement data of the oscilloscope;
s4: analyzing CAN faults according to the function or logic of the node with the error frame;
s5: interference source and interference path analysis;
in step S1, the specific steps of data acquisition and analysis by the CAN bus data acquisition device are as follows:
(1-1) CAN bus data acquisition equipment acquires CAN network data and eliminates CAN bus faults caused by inconsistent baud rates of all nodes, poor connection of wire harnesses or uncomfortable matching resistance;
(1-2) if the node fails to send data due to excessive non-error frames and no condition exists, executing step S2, if the node fails to send data due to excessive non-error frames and one or more conditions are met, executing step S4;
(1-3) if there are error frames or the error frames are too many to cause the node to be lost, executing step S3;
in step S2, the specific steps of analyzing the electromagnetic compatibility of the lost node are as follows:
(2-1) if the working state of the node changes, the voltage change rate of the high-voltage circuit is greater than 1 millisecond per volt or the current change rate is greater than 1 millisecond per ampere, the high-voltage circuit interferes with the low-voltage circuit, so that the low-voltage circuit cannot normally operate, and the node is lost, and whether the main control board circuit is interfered or not is mainly analyzed; otherwise, the present step S2 is executed;
(2-2) analyzing the working state of the vehicle before and after the node is lost;
(2-3) before and after the vehicle working state changes, other parts of the high-voltage circuit, of which the voltage change rate is more than 1 millisecond per volt or the current change rate is more than 1 millisecond per ampere, are defined as electronic parts which interfere with the node;
(2-4) analyzing the circuit interference frequency of all electronic parts with interference at the moment of node loss by using an oscilloscope, measuring a signal with completely consistent waveform for a plurality of times continuously by using the oscilloscope, namely a periodic interference signal, reading the interval time between adjacent periodic signals, and taking the reciprocal of the interval time to obtain the interference frequency of the circuit;
(2-5) checking whether all electronic parts which can be interference sources are directly connected with the node through the connector or the wiring harnesses of the electronic parts are directly bundled together with the wiring harnesses of the node, and regarding the existence of the above-described parts as key analysis objects;
(2-6) performing troubleshooting on the electronic parts becoming interference sources through an elimination method by using a spectrum analyzer and a near-field probe and determining the interference sources;
and (2-7) confirming an interference path according to the checked result and combining the data of the spectrum analyzer.
2. The method for locating the electromagnetic interference source in the vehicle based on the CAN bus data as claimed in claim 1, wherein in the step S3, the oscilloscope measurement data analysis specifically comprises the steps of:
(3-1) measuring voltage signals of CAN _ H to CAN ground and CAN _ L to CAN ground respectively to determine whether CAN _ H and CAN _ L signal lines are interfered, if the measurement result conforms to the standard ISO11898-1-2003 road vehicle-controller area network-data link layer and physical signals, the CAN bus is not interfered, and the step S3 is finished; otherwise, continuing to execute step S3;
(3-2) observing periodic interference signals appearing on the CAN _ H and the CAN _ L, measuring and reading the interval time between adjacent periodic signals through an oscilloscope, and taking the reciprocal of the interval time to determine the interference frequency of the interval time;
(3-3) analyzing aperiodic interference signals appearing on the CAN _ H and the CAN _ L according to the working state of the vehicle, and confirming the electronic parts generating interference;
(3-4) calculating the differential signal Vdiff＝VCAN_H-VCAN_L(ii) a If ringing during the explicit/implicit level conversion causes the bit sampling point to exceed the normal range, adjusting the matching resistance;
and (3-5) through differential signal data analysis, determining interference sources influencing the quality of the differential signals as interference sources generating interference on CAN network data, and determining other interference sources as potential interference sources.
3. The method for locating the electromagnetic interference source in the vehicle based on the CAN bus data as claimed in claim 2, wherein the step S4 of analyzing the CAN fault according to the function or logic of the node where the error frame occurs includes the following steps:
(4-1) pulling the node out of the CAN network, and independently measuring and analyzing a CAN physical level signal of the node;
and (4-2) acquiring message data and analyzing whether the CAN sending program of the node is abnormal or not.
4. The method for locating the electromagnetic interference source in the vehicle based on the CAN bus data as claimed in claim 2, wherein the step S5 of determining the frequency of the interference source according to the periodic interference signal comprises the following steps:
(5-1) determining an interference source frequency from the periodic interference signal;
(5-2) determining a sudden interference source according to the working state of the vehicle;
(5-3) analyzing by referring to the electromagnetic compatibility test report of each electronic part according to the results of the step (5-1) and the step (5-2) to determine a possible interference source;
(5-4) distinguishing a potential interference source from an interference source having an influence on CAN data by the measured or calculated differential signal;
and (5-5) analyzing and determining an interference path by combining data of a spectrum analyzer according to the electronic parts generating interference, the physical connection mode and the physical distance between the wiring harness and the CAN bus wiring harness.
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| CN111948469B (en) * | 2019-05-17 | 2021-06-08 | 中国科学院声学研究所 | CAN bus electromagnetic compatibility detection method and system |
| CN113342592B (en) * | 2020-03-03 | 2023-08-25 | 合肥杰发科技有限公司 | Disconnection detection method, device and medium of hot plug equipment |
| CN111665821B (en) * | 2020-06-08 | 2022-06-07 | 重庆长安汽车股份有限公司 | Error frame checking method based on vehicle diagnosis service |
| CN112003774B (en) * | 2020-07-22 | 2021-12-14 | 东风汽车集团有限公司 | Method, system and storage medium for checking error frame of automobile CAN bus |
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