Method and system for wireless monitoring of communication data for charging piles

Abstract

This invention discloses a wireless monitoring method and system for communication data of charging piles. The monitoring method includes: receiving electromagnetic signals radiated from a CAN bus; performing analog-to-digital conversion on the electromagnetic signals to obtain a digitized signal to be processed; detecting the signal amplitude of sampled data in the signal to be processed in a time sequence; when the signal amplitude of any sampled data exceeds a threshold, inverting the level state of the sampled data to obtain feature data; filling a corresponding number of follower data between two adjacent feature data to obtain a monitoring signal including feature data and follower data; and performing frame parsing on the monitoring signal based on the CAN bus data frame transmission structure to obtain communication data. The above monitoring method for detecting communication data of charging piles has low detection cost, avoids repeated data detection, and offers fast detection speed and high accuracy.

Description

Technical Field

[0001] This invention relates to the field of communication data monitoring technology, and in particular to a wireless monitoring method and system for communication data of charging piles. Background Technology

[0002] With the increasing popularity of electric vehicles, the safety of electric vehicle charging has become a growing concern. Currently, the standard for electric vehicle charging, GB / T 27930-2015 "Communication Protocol between Off-board Conductive Chargers and Battery Management Systems for Electric Vehicles," does not address information security issues, posing potential cybersecurity risks. Therefore, it is necessary to evaluate the security of communication between charging piles and vehicles. Existing vehicle-charging pile communication security testing requires the use of relay equipment independent of both the charging pile and the vehicle to collect communication data. Specifically, the relay equipment connects to the communication terminals of both the charging pile and the vehicle's BMS system via a communication switching system to receive communication data between the charging pile and the vehicle during charging, and then evaluates the received communication data. This evaluation method is limited by the need for relay equipment independent of the charging pile, requiring improvements to the charging gun structure connected to the charging pile and the installation of relay communication lines. For charging piles without a relay communication system, their communication data cannot be tested, while configuring a relay communication system for charging piles increases costs. Summary of the Invention

[0003] The purpose of this invention is to provide a wireless monitoring method and system for charging piles that can acquire communication data from charging piles that do not have relay communication functions.

[0004] To achieve the above objectives, this invention discloses a wireless monitoring method for communication data of charging piles, used for acquiring communication data between the charging pile and the vehicle to be charged. The charging pile communicates with the vehicle to be charged based on a CAN bus. The monitoring method includes:

[0005] Receive the electromagnetic signals radiated from the CAN bus detected by the inductive electromagnetic probe;

[0006] The electromagnetic signal is subjected to analog-to-digital conversion to obtain a digitized signal to be processed;

[0007] The signal amplitude of the sampled data in the signal to be processed is detected in a time sequence;

[0008] When the signal amplitude of any of the sampled data exceeds a preset positive threshold in the positive direction or exceeds a preset negative threshold in the negative direction, the level state of the sampled data is flipped to obtain feature data.

[0009] Based on the time length between two adjacent feature data, a corresponding number of follow data are filled between the two adjacent feature data. The level state of the follow data follows the level state of the previous feature data, so as to obtain a monitoring signal including the feature data and the follow data.

[0010] Furthermore, when the feature data is detected at the current moment, the detection of the signal amplitude of the corresponding sampled data is stopped within a preset time T, where 1 / 5C < T < 1 / 2C, and C is the communication data transmission cycle of the CAN bus.

[0011] Based on the CAN bus data frame transmission structure, the monitoring signal is parsed to obtain communication data.

[0012] Preferably, 2. The wireless monitoring method for communication data of charging piles according to claim 1, wherein T = 1 / 4C.

[0013] Preferably, when the signal amplitude of any of the sampled data exceeds a preset positive threshold in the positive direction or exceeds a preset negative threshold in the negative direction, the amplitude direction of the sampled data at the current moment is recorded, and an XOR operation is performed with the amplitude direction of the previously stored sampled data. When the operation result is 1, the level state of the current sampled data is toggled to obtain the feature data. When the operation result is 0, the level state of the current sampled data is maintained to obtain the feature data.

[0014] Preferably, in the monitoring signal, when five consecutive data with the same level state appear, a data with the opposite level state to the previous five data is inserted into the next data bit.

[0015] Preferably, an RC filter is used to filter out low-frequency interference signals in the electromagnetic signal.

[0016] Preferably, an integrated operational amplifier is used to amplify the electromagnetic signal.

[0017] The present invention also discloses a wireless monitoring system for communication data of charging piles, used for acquiring communication data between charging piles and vehicles to be charged, wherein the charging pile communicates with the vehicles to be charged based on a CAN bus, and the monitoring system operates based on the above-mentioned wireless method for communication data of charging piles.

[0018] The present invention also discloses another wireless monitoring system for communication data of charging piles, which includes:

[0019] One or more processors;

[0020] Memory;

[0021] And one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the programs including instructions for performing the wireless monitoring method for communication data of charging piles as described above.

[0022] The present invention also discloses a computer-readable storage medium, characterized in that it includes a computer program, which can be executed by a processor to perform the wireless monitoring method for communication data of charging piles as described above.

[0023] Compared with the prior art, the wireless monitoring method for communication data disclosed in the above-mentioned technical solution of the present invention is based on the different characteristics of electromagnetic signals leaked by different data transmission behaviors in communication transmission cables. By analyzing the electromagnetic signals radiated from the CAN bus, the data content transmitted by the CAN bus is inferred. Thus, the communication data between the charging pile and the vehicle to be charged can be obtained by modifying the charging cable without physical contact, so as to analyze whether it conforms to the standard specifications. Moreover, when a change in the level state of each sampled signal is detected (that is, characteristic data is detected), the detection is stopped within a preset time to avoid repeated detection of a single data. This not only effectively improves the speed of electromagnetic signal analysis, but also improves the accuracy of analysis. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the implementation of the monitoring method in this embodiment of the invention.

[0025] Figure 2 This is a waveform diagram of an electromagnetic signal emitted by the CAN bus.

[0026] Figure 3 This is an electromagnetic signal waveform diagram corresponding to a data frame transmitted via the CAN bus in an embodiment of the present invention. Detailed Implementation

[0027] To illustrate the technical content, structural features, objectives, and effects of the present invention in detail, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0028] This embodiment discloses a wireless monitoring method for communication data of charging piles. It acquires communication data wirelessly when communication occurs between the charging pile and the vehicle being charged. The charging pile communicates with the vehicle via a CAN bus. In this embodiment, this monitoring method can acquire communication data from any charging pile based on CAN bus communication without requiring modifications to the charging pile's circuit structure or the laying of communication cables.

[0029] In this embodiment, the basic principle for extracting communication data based on electromagnetic signals leaked from the CAN bus is as follows:

[0030] GB / T 27930-2015 specifies that charging piles and vehicles to be charged should communicate using the CAN protocol. CAN signal is a digital differential signal that is transmitted using a pair of differential signal lines. It is defined that when the voltage difference between the two lines is greater than 0.9V, it is a dominant level, and when it is less than 0.5V, it is a recessive level. The dominant level is represented by logic "0", and the recessive level is represented by logic "1".

[0031] If the CAN bus level needs to be changed, the potential on the CAN bus must be changed, which will inevitably generate current on the CAN bus. As can be seen from Maxwell's equations, the CAN bus will radiate electromagnetic waves to the surroundings, and different data transmissions on the CAN bus will produce different voltage and current changes, which will cause the leaked electromagnetic signals to have different characteristics.

[0032] Specifically, when the CAN bus is in an idle state, the leaked electromagnetic signal is a relatively stable ripple, such as... Figure 2 Parts A and C in the diagram appear as a straight line overall. A noticeable electromagnetic wave waveform, or spike pulse, only appears when the transmitted data changes (e.g., the previous transmitted data was 0, and the next transmitted data is 1). Figure 2 The two parts are B and C. Therefore, when a spike appears on the waveform of the electromagnetic wave, it means that the level of the CAN bus transmission has changed, that is, a 0 / 1 flip has occurred, and the level state of the data corresponding to the ripple signal between two spikes is the same as the level state of the data corresponding to the previous spike.

[0033] Therefore, simply detecting electromagnetic waves around the CAN bus only reveals a change in the current CAN bus level. However, since the CAN bus remains hidden in its idle state, starting from the initial state, each received spike pulse toggles the recorded CAN bus level, allowing for the reverse deduction of the actual level on the CAN bus. Thus, prolonged monitoring allows the acquisition of the binary data stream transmitted on the CAN bus. Based on the CAN bus's data frame structure, this binary data stream can then be parsed to obtain the communication content transmitted on the CAN bus.

[0034] Based on the above-mentioned basic principle of extracting communication data from electromagnetic signals leaked from the CAN bus, such as Figure 1 The monitoring method in this embodiment includes the following steps:

[0035] S1: Provide an inductive electromagnetic probe and place it near the CAN bus of the charging pile to receive the electromagnetic signals radiated from the CAN bus detected by the probe, such as... Figure 3 .

[0036] S2: Perform analog-to-digital conversion (A / D conversion) on the electromagnetic signal to obtain a digitized signal to be processed.

[0037] S3: Driven by the clock signal of the CAN bus, detect the signal amplitude of the sampled data in the signal to be processed one by one in sequence.

[0038] S4: For the current sampled data, determine whether the signal amplitude exceeds a preset positive threshold in the positive direction or a preset negative threshold in the negative direction. That is, when the signal amplitude is positive, the signal amplitude exceeds the preset positive threshold in the positive direction, and when the signal amplitude is negative, the signal amplitude exceeds the preset negative threshold in the negative direction. If yes, execute the following step S5; otherwise, return to step S3 and read the next sampled data.

[0039] S5: The sampled data corresponds to the spike pulse of the analog electromagnetic signal, which is the node where the transmitted data changes. The level state of the sampled data at this time node is flipped to obtain the feature data.

[0040] S6: Based on the time length between two adjacent feature data points, fill the gaps between them with a corresponding number of follower data points. The level state of the follower data points follows the level state of the preceding feature data point, thus obtaining a monitoring signal that includes both feature data and follower data. For example, in Figure 3 In part E, the characteristic data corresponding to the first spike J1 is "0", while the characteristic data corresponding to the next second spike 2 is "1". Part F following the first spike J1 is ripple, indicating that the communication data has not changed during this period. Therefore, the number of data transmitted by the CAN bus during this period can be calculated based on the time between the first spike J1 and the second spike 2. For example, if the CAN bus should transmit three data during this period, then three following data "0"s are filled between the characteristic data "0" and "1", thus generating a monitoring signal of "00001". This process continues to generate a complete monitoring signal corresponding to the electromagnetic signal.

[0041] Furthermore, since the clock frequency (50MHz to 100MHz) used by the A / D converter to drive data sampling is much higher than the clock frequency of the CAN bus (250kb), to avoid the same spike pulse data in the electromagnetic signal being repeatedly detected, when characteristic data is detected at the current moment, the detection of the signal amplitude of the corresponding sampled data is stopped within a preset time T, where 1 / 5C < T < 1 / 2C, where C is the communication data transmission cycle of the CAN bus. Preferably, in this embodiment, T = 1 / 4C.

[0042] S7: Based on the CAN bus data frame transmission structure, it performs frame parsing on the monitoring signal to obtain communication data.

[0043] In the above embodiments, based on the principle that electromagnetic signals leaked from different data transmission behaviors in communication cables exhibit different characteristics, the data content transmitted by the CAN bus is inferred by analyzing the electromagnetic signals radiated from the CAN bus. This allows for the acquisition of communication data between the charging pile and the vehicle being charged without physically modifying the charging cable, enabling analysis of whether the data conforms to standards and specifications. This method is not only convenient to operate but also eliminates the need to modify the charging pile, reducing the hardware cost of detecting charging pile communication data. Furthermore, when a change in the level of each sampled signal is detected (i.e., characteristic data is detected), detection stops within a preset time to avoid repeated detection of single communication data, thereby effectively improving the speed of electromagnetic signal analysis.

[0044] Furthermore, for the ASK segment of the CAN data frame, CAN bus control shifts from the transmitting end to the receiving end, resulting in two consecutive spikes in the electromagnetic signal in the same direction. The CAN bus level remains unchanged. Figure 3 The spikes J3 and J4 are detected. If the restored level state is toggled once each time a spike is detected, it can be found that the CAN bus state represented by the monitoring signal will become dominant after the current CAN data frame transmission ends. This is contrary to the standard CAN data frame and will cause malfunctions in the detection of the next CAN data frame.

[0045] Therefore, when the signal amplitude of any sampled data exceeds a preset positive threshold in the positive direction or exceeds a preset negative threshold in the negative direction, the amplitude direction of the sampled data at the current moment is recorded and XORed with the amplitude direction of the saved previous sampled data. When the result is 1, the level state of the current sampled data is toggled to obtain feature data. When the result is 0, the level state of the current sampled data is maintained to obtain feature data.

[0046] Specifically, the direction of the signal amplitude A recorded from the sampled data is d, and d is subject to the following limitations:

[0047]

[0048] Where a1 is the positive threshold and a2 is the negative threshold.

[0049] Therefore, after obtaining the direction d of the signal amplitude A of the current sampled data, an XOR operation is performed with the direction d' of the signal amplitude A of the previous sampled data, as shown in the following formula:

[0050]

[0051] When T=1, the level state of the restored sampled data is flipped to obtain the feature data; conversely, when T=0, the level state of the sampled data is maintained to obtain the feature data. That is, the feature data obtained at this time is the same as the level state of the sampled data.

[0052] On the other hand, during the transmission of communication data on the CAN bus, interference and sudden interruptions are unavoidable, making it impossible to always guarantee the detection of a complete CAN data frame. When a complete CAN data frame cannot be obtained through electromagnetic signals, the restored level cannot be kept in an invisible state when the CAN bus is idle, preventing further data recovery. To address this, a further improvement is made: when five consecutive data points with the same level appear in the monitoring signal, a data point with the opposite level to the previous five is inserted into the next data bit. In this embodiment, reflected in the electromagnetic signal radiated from the CAN bus, if no next spike is received within five data bit intervals, it indicates a reception timeout, and the CAN bus is considered to be in an idle state. The restored level is automatically set to invisible, thus avoiding interference with the next data recovery.

[0053] On the other hand, after obtaining electromagnetic signals using an electromagnetic probe, an RC filter is used to filter out low-frequency interference signals in the electromagnetic signals in order to improve the accuracy of the parsed communication content.

[0054] Furthermore, an integrated operational amplifier is used to amplify the electromagnetic signal. In this embodiment, the processing of the electromagnetic signal by the integrated operational amplifier significantly improves the performance of the back-end A / D converter. It also improves the signal-to-noise ratio of the electromagnetic signal, reduces the requirement for the number of bits in the A / D conversion, reduces computational complexity, suppresses signal oscillation, and converts it into a unidirectional pulse signal, avoiding misinterpretation of subsequent spike signals.

[0055] This invention also discloses another wireless communication data monitoring system, which includes one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors. The programs include instructions for performing the wireless communication data monitoring method as described above. The processor may be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, used to execute the relevant programs to implement the functions required by the modules in the wireless communication data monitoring system of this application embodiment, or to execute the wireless communication data monitoring method of this application embodiment.

[0056] This invention also discloses a computer-readable storage medium comprising a computer program executable by a processor to perform the wireless monitoring method for communication data as described above. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center integrating one or more available media. The available medium can be read-only memory (ROM), random access memory (RAM), or magnetic media, such as floppy disks, hard disks, magnetic tapes, magnetic disks, or optical media, such as digital versatile discs (DVDs), or semiconductor media, such as solid-state disks (SSDs).

[0057] This application also discloses a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. The processor of an electronic device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the electronic device to perform the aforementioned wireless monitoring method for communication data.

[0058] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A wireless monitoring method for communication data of a charging pile, used to acquire communication data between the charging pile and the vehicle to be charged, wherein the charging pile communicates with the vehicle to be charged based on a CAN bus, characterized in that... The monitoring method includes: Receive the electromagnetic signals radiated from the CAN bus detected by the inductive electromagnetic probe; The electromagnetic signal is subjected to analog-to-digital conversion to obtain a digitized signal to be processed; The signal amplitude of the sampled data in the signal to be processed is detected in a time sequence; When the signal amplitude of any of the sampled data exceeds a preset positive threshold in the positive direction or exceeds a preset negative threshold in the negative direction, the level state of the sampled data is flipped to obtain feature data. Based on the time length between two adjacent feature data, a corresponding number of follow data are filled between the two adjacent feature data. The level state of the follow data follows the level state of the previous feature data, so as to obtain a monitoring signal including the feature data and the follow data. Furthermore, when the feature data is detected at the current moment, the detection of the signal amplitude of the corresponding sampled data is stopped within a preset time T, where 1 / 5C < T < 1 / 2C, and C is the communication data transmission cycle of the CAN bus. Based on the CAN bus data frame transmission structure, the monitoring signal is parsed to obtain communication data.

2. The wireless monitoring method for communication data of charging piles according to claim 1, characterized in that, T = 1 / 4C.

3. The wireless monitoring method for communication data of charging piles according to claim 1, characterized in that, When the signal amplitude of any of the sampled data exceeds a preset positive threshold in the positive direction or exceeds a preset negative threshold in the negative direction, the amplitude direction of the sampled data at the current moment is recorded and XORed with the amplitude direction of the previously saved sampled data. When the result is 1, the level state of the current sampled data is toggled to obtain the feature data. When the result is 0, the level state of the current sampled data is maintained to obtain the feature data.

4. The wireless monitoring method for communication data of charging piles according to claim 1, characterized in that, In the monitoring signal, when five consecutive data with the same level state appear, a data with the opposite level state to the previous five data is inserted into the next data bit.

5. The wireless monitoring method for communication data of charging piles according to claim 1, characterized in that, An RC filter is used to filter out low-frequency interference signals in the electromagnetic signal.

6. The wireless monitoring method for communication data of charging piles according to claim 1, characterized in that, The electromagnetic signal is amplified using an integrated operational amplifier.

7. A wireless monitoring system for communication data of a charging pile, used to acquire communication data between the charging pile and the vehicle to be charged, wherein the charging pile communicates with the vehicle to be charged based on a CAN bus, characterized in that, The monitoring system operates based on the wireless communication data method for charging piles as described in any one of claims 1 to 6.

8. A wireless monitoring system for communication data of charging piles, characterized in that, include: One or more processors; Memory; And one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the programs including instructions for performing the wireless monitoring method for communication data of charging piles as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, It includes a computer program that can be executed by a processor to perform the wireless monitoring method for communication data of a charging pile as described in any one of claims 1 to 6.

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