CN116184306A - CAN communication isolation device for resisting pulse group and interference elimination method - Google Patents
CAN communication isolation device for resisting pulse group and interference elimination method Download PDFInfo
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- CN116184306A CN116184306A CN202310494853.4A CN202310494853A CN116184306A CN 116184306 A CN116184306 A CN 116184306A CN 202310494853 A CN202310494853 A CN 202310494853A CN 116184306 A CN116184306 A CN 116184306A
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R35/04—Testing or calibrating of apparatus covered by the other groups of this subclass of instruments for measuring time integral of power or current
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The invention discloses a CAN communication isolation device of anti-pulse group and a de-interference method, wherein the device comprises the following steps: the first communication isolation circuit is used for physically isolating and high-frequency filtering the test CAN signal to obtain a pulse-burst-free test signal; the microcontroller is used for checking the pulse-burst-free test signal and removing false fidelity to obtain an effective test signal; the second communication isolation circuit is used for carrying out secondary physical isolation and filtering on the effective test signal to obtain a target test signal; the first and second communication isolation circuits include: the voltage amplitude limiting sub-circuit is used for carrying out differential mode filtering on the CAN signal and limiting the signal amplitude of the CAN signal below a set voltage; the filter sub-circuit is used for filtering the limited signal to obtain a stable-voltage low-frequency signal; the isolated CAN transceiver is used for converting the stable low-frequency signal into a TTL level signal; the RC filter sub-circuit is used for RC filtering the TTL level signal to obtain a test CAN signal which is output to the next stage.
Description
Technical Field
The invention relates to the technical field of CAN signal testing, in particular to a CAN communication isolation device for resisting pulse groups and an interference elimination method.
Background
When battery management system BMS prevents electric fast transient pulse group test, often meet if the equipment under test need communicate with the computer through CAN bus, the electric fast transient pulse group interference signal on the equipment under test CAN be transmitted to the computer port along the communication line that the CAN bus constitutes, and because the computer CAN't resist the interference of electric fast transient pulse group, finally cause the communication to receive the interference, lead to received data exception, the condition of unable normal demonstration appears, serious even appear the direct dead halt of computer.
In the related art, when the tested device and the computer perform CAN communication, in order to protect the computer from being affected by the electric fast transient pulse group interference signal of the tested device end, a CAN signal conversion box is additionally arranged in a CAN communication line, the CAN signal conversion box converts a CAN signal into a USB signal which CAN be received by the computer, and then the computer analyzes and displays corresponding content of the received signal, so that a data display result is achieved. However, the isolation effect of the CAN signal conversion box is poor, so that the interference signals of the electric fast transient pulse groups cannot be completely filtered, the interference signals CAN still be transmitted to the next stage along the isolation power supply and the communication signal line, and finally transmitted to the computer terminal, and the computer CAN still be influenced by the interference signals of the electric fast transient pulse groups. Therefore, it is desirable to provide a device for improving the filtering of the interference signal of the electrical fast transient burst in the test CAN signal, so as to avoid the interference of the interference signal of the electrical fast transient burst to the computer.
Disclosure of Invention
Aiming at the technical problem that the interference signals of the electric fast transient pulse groups in the test CAN signals are not thoroughly filtered in the prior art, the invention provides a CAN communication isolation device for resisting the pulse groups and an interference elimination method.
In order to achieve the above purpose, the invention is realized by the following technical scheme:
in a first aspect of the present invention, a CAN communication isolation device for resisting pulse packets is provided, the device comprising: the device comprises a first communication isolation circuit, a microcontroller connected with the output end of the first communication isolation circuit, and a second communication isolation circuit connected with the output end of the microcontroller;
the first communication isolation circuit is used for carrying out physical isolation and high-frequency filtering on an input original test CAN signal to obtain a pulse group-free test CAN signal with pulse group interference filtered;
the microcontroller is used for checking the pulse-burst-free test CAN signal and removing false fidelity to obtain an effective test CAN signal;
the second communication isolation circuit is used for carrying out secondary physical isolation and filtering on the effective test CAN signal to obtain a target test CAN signal for testing, and outputting the target test CAN signal to a CAN conversion box;
wherein, first communication isolation circuit and second communication isolation circuit all include: the device comprises a voltage amplitude limiting sub-circuit, a filtering sub-circuit connected with the voltage amplitude limiting sub-circuit, an isolated CAN transceiver connected with the filtering sub-circuit and an RC filtering sub-circuit connected with the isolated CAN transceiver;
the voltage amplitude limiting sub-circuit is used for carrying out differential mode filtering processing on an input CAN signal so as to limit the signal amplitude of the CAN signal below a set voltage;
the filter sub-circuit is used for performing voltage stabilizing filtering and high-frequency filtering on the CAN signal with the signal amplitude below the set voltage to obtain a voltage stabilizing low-frequency CAN signal;
the isolated CAN transceiver is used for converting the stable low-frequency CAN signal into a TTL level signal;
the RC filter sub-circuit is used for RC filtering the TTL level signal to obtain a test CAN signal which is output to the next stage.
In one embodiment, the voltage clipping sub-circuit includes:
a gas discharge tube TV1, a transient suppression diode D3 having a first end connected to a first pole of the gas discharge tube TV1, a transient suppression diode D4 having a first end connected to the first pole of the gas discharge tube TV1, and a transient suppression diode D5 having a first end connected to a second pole of the gas discharge tube TV 1;
wherein a second end of the transient suppression diode D3 is connected to the second pole of the gas discharge tube TV 1;
a second end of the transient suppression diode D4 and a second end of the transient suppression diode D5 are grounded;
the first pole of the gas discharge tube TV1 is configured as CANH input of the voltage clipping sub-circuit, and the second pole of the gas discharge tube TV1 is configured as CANL input of the voltage clipping sub-circuit;
the connection point of the first end of the transient suppression diode D3 with the first pole of the gas discharge tube TV1 is configured as CANH output of the voltage clipping sub-circuit, and the connection point of the second end of the transient suppression diode D3 with the second pole of the gas discharge tube TV1 is configured as CANL output of the voltage clipping sub-circuit.
In one embodiment, the filtering sub-circuit includes:
resistor R2, resistor R6, resistor R4, electrostatic protection diode D1, common mode inductance L2, capacitor C10 and capacitor C11;
wherein a first end of the resistor R2 is configured as a CANH input of the filter sub-circuit and a first end of the resistor R6 is configured as a CANL input of the filter sub-circuit;
the second end of the resistor R2 is connected with the No. 4 connecting end of the common-mode inductor L2, and the second end of the resistor R6 is connected with the No. 3 connecting end of the common-mode inductor L2;
the resistor R4 is connected between the No. 4 connection end of the common-mode inductor L2 and the No. 3 connection end of the common-mode inductor L2, a first end of the electrostatic protection diode D1 is connected with a CANH signal, a first end of the electrostatic protection diode D1 is connected with a CANL signal, and a third end of the electrostatic protection diode D1 is grounded;
the first end of the capacitor C10 is connected to the No. 1 connection end of the common-mode inductor L2 and configured as the CANH output end of the filter sub-circuit after connection, and the first end of the capacitor C11 is connected to the No. 2 connection end of the common-mode inductor L2 and configured as the CANL output end of the filter sub-circuit after connection.
In one embodiment, the RC filter subcircuit includes:
the device comprises a resistor R3, a resistor R5, a capacitor C8 and a capacitor C9, wherein a first end of the resistor R3 is connected with a first end of the capacitor C8 and is connected with a TXD pin of the isolated CAN transceiver after being connected, a second end of the capacitor C8 is grounded, and a second end of the resistor R3 is configured as a signal transmitting end of a communication isolated circuit and is used for outputting a test CAN signal to next-stage equipment;
the first end of the resistor R5 is connected with the first end of the capacitor C9 and is connected with the RXD pin of the isolated CAN transceiver after being connected, the second end of the capacitor C9 is grounded, and the second end of the resistor R5 is configured as a signal receiving end of a communication isolation circuit and is used for receiving signals uploaded by next-stage equipment.
In one embodiment, the first communication isolation circuit and the second communication isolation circuit each include: the LC power supply filter sub-circuit comprises an inductor L1, a capacitor C2, a capacitor C4 and a capacitor C6;
the first end of the inductor L1 is connected with a VCC5 power supply, the second end of the inductor L1 is connected with the capacitor C2, the capacitor C4 and the first end of the capacitor C6, and is connected with the power supply VCC1 of the isolated CAN transceiver after being connected so as to provide a 5V direct current power supply for the isolated CAN transceiver;
the second ends of the capacitor C2, the capacitor C4 and the capacitor C6 are connected and grounded after being connected, and are connected with the first grounding end GND1 of the isolated CAN transceiver after being connected.
In one embodiment, the first communication isolation circuit and the second communication isolation circuit each include: the capacitive power supply filter sub-circuit comprises a capacitor C3, a capacitor C5 and a capacitor C7;
the first ends of the capacitor C3, the capacitor C5 and the capacitor C7 are connected together and respectively connected with a V5A power supply and a power supply VCC2 of the isolated CAN transceiver after being connected so as to provide a 5V direct current power supply for the isolated CAN transceiver;
the second ends of the capacitor C3, the capacitor C5 and the capacitor 7 are connected together and connected to the second ground GND2 of the isolated CAN transceiver after being connected.
In a second aspect of the embodiments of the present invention, a method for interference cancellation of a CAN communication isolation device based on an anti-pulse group is provided, where the method is applied to any one of the anti-pulse group CAN communication isolation devices in the first aspect, and the method includes:
performing differential mode filtering processing on an input CAN signal through a voltage amplitude limiting sub-circuit in a first communication isolation circuit so as to limit the signal amplitude of the CAN signal below a set voltage;
the CAN signals with the signal amplitude below the set voltage are subjected to voltage stabilizing filtering and high-frequency filtering through a filtering sub-circuit in the first communication isolation circuit, so that voltage stabilizing low-frequency CAN signals are obtained;
converting the stable low-frequency CAN signal into a TTL level signal through an isolated CAN transceiver in the first communication isolation circuit;
RC filtering is carried out on the TTL level signal through an RC filtering sub-circuit in the first communication isolation circuit, so that a pulse group-free test CAN signal with pulse group interference filtered out is obtained;
checking and removing false fidelity of the pulse-burst-free test CAN signal through the microcontroller to obtain an effective test CAN signal;
and performing secondary physical isolation and filtering on the effective test CAN signal through a second communication isolation circuit to obtain a target test CAN signal for testing, and outputting the target test CAN signal to a CAN conversion box.
Advantageous effects
The invention provides a CAN communication isolation device for resisting pulse groups and an interference elimination method. Compared with the prior art, the method has the following beneficial effects:
the invention is used for carrying out physical isolation and high-frequency filtering on an input original test CAN signal through a first communication isolation circuit to obtain a pulse group-free test CAN signal with pulse group interference filtered; the microcontroller is used for checking and removing false fidelity of the pulse-burst-free test CAN signal to obtain an effective test CAN signal; the second communication isolation circuit is used for carrying out secondary physical isolation and filtering on the effective test CAN signals to obtain target test CAN signals for testing, and outputting the target test CAN signals to the CAN conversion box; the device thoroughly isolates the electric fast transient pulse group interference signals through the first communication isolation circuit and the second communication isolation circuit, improves the accuracy of testing CAN signals, and avoids influencing upper equipment such as a computer.
Further, the first communication isolation circuit and the second communication isolation circuit each include: the device comprises a voltage amplitude limiting sub-circuit, a filtering sub-circuit connected with the voltage amplitude limiting sub-circuit, an isolated CAN transceiver connected with the filtering sub-circuit and an RC filtering sub-circuit connected with the isolated CAN transceiver; the voltage limiting sub-circuit is used for carrying out differential mode filtering processing on the input CAN signal so as to limit the signal amplitude of the CAN signal below a set voltage; the filtering sub-circuit is used for performing voltage stabilizing filtering and high-frequency filtering on the CAN signal with the signal amplitude below the set voltage to obtain a voltage stabilizing low-frequency CAN signal; the isolated CAN transceiver is used for converting the stable low-frequency CAN signal into a TTL level signal; the RC filter sub-circuit is used for RC filtering the TTL level signal to obtain a test CAN signal which is output to the next stage. In this way, the common mode signal and the differential mode signal existing in the interference signal CAN be filtered through the voltage amplitude limiting sub-circuit, the energy of the interference signal is further reduced through the filtering sub-circuit, the differential mode interference signal is further filtered and the high-frequency interference signal is subjected to bypass filtering, so that no interference signal or fewer interference signals exist on the CAN signal of the isolated CAN transceiver. Further, the residual interference signals are subjected to bypass filtering again through the RC filter sub-circuit.
In addition, the CAN communication isolation device for resisting the pulse group is simple in operation, convenient in wiring and capable of being plugged and used at the same time, and the convenience of testing is improved.
Drawings
Fig. 1 is a schematic diagram of a CAN communication isolation device with anti-burst according to the present invention.
Fig. 2 is a circuit diagram of a communication isolation circuit according to the present invention.
Fig. 3 is a schematic circuit diagram of a microcontroller 102 according to the present invention.
Fig. 4 is a flowchart of a method for interference cancellation of a CAN communication isolation device based on an anti-burst according to the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, the present invention provides a technical solution: a CAN communication isolation device resistant to pulse groups, the device 100 comprising: the device comprises a first communication isolation circuit 101, a microcontroller 102 connected with the output end of the first communication isolation circuit 101, and a second communication isolation circuit 103 connected with the output end of the microcontroller 102;
the first communication isolation circuit 101 is configured to perform physical isolation and high-frequency filtering on an input original test CAN signal to obtain a pulse group-free test CAN signal with pulse group interference filtered;
the microcontroller 102 is configured to perform checksum and spurious elimination on the burst-free test CAN signal to obtain an effective test CAN signal;
in one embodiment, the microcontroller 102 caches the query command sent by the CAN conversion box and continuously sends the query command to the device under test in case that the test CAN signals of the current test stage are all invalid CAN signals, so that the device under test resends the test CAN signals for the query command until the corresponding signals return to be correct. The query instruction corresponding to the CAN conversion box is generated according to the test instruction of the upper equipment such as a computer and the like.
The second communication isolation circuit 103 is configured to perform secondary physical isolation and filtering on the effective test CAN signal to obtain a target test CAN signal for testing, and output the target test CAN signal to a CAN conversion box;
referring to fig. 1, a first communication isolation circuit 101 receives a raw test CAN signal transmitted by a device under test, and a second communication isolation circuit 103 transmits a target test CAN signal to a CAN conversion box.
Referring to fig. 2, the first communication isolation circuit 101 and the second communication isolation circuit 103 each include: a voltage limiter sub-circuit 1001, a filter sub-circuit 1002 connected to the voltage limiter sub-circuit 1001, an isolated CAN transceiver U1 connected to the filter sub-circuit 1002, and an RC filter sub-circuit 1002 connected to the isolated CAN transceiver U1;
the voltage limiting sub-circuit 1001 is configured to perform differential mode filtering processing on an input CAN signal, so as to limit a signal amplitude of the CAN signal to be below a set voltage;
in the embodiment of the disclosure, the signal amplitude of the CAN signal may be limited to below 7.5V, i.e., the set voltage may be 7.5V.
The filtering sub-circuit 1002 is configured to perform voltage stabilizing filtering and high-frequency filtering on a CAN signal with a signal amplitude below a set voltage, so as to obtain a voltage stabilizing low-frequency CAN signal;
the isolated CAN transceiver U1 is used for converting the stable low-frequency CAN signal into a TTL level signal;
the RC filter sub-circuit 1003 is configured to perform RC filtering on the TTL level signal to obtain a test CAN signal that is output to a next stage.
The device performs physical isolation and high-frequency filtering on an input original test CAN signal through a first communication isolation circuit to obtain a pulse group-free test CAN signal with pulse group interference filtered; checking and removing false fidelity of the pulse-burst-free test CAN signal through the microcontroller to obtain an effective test CAN signal; performing secondary physical isolation and filtering on the effective test CAN signal through a second communication isolation circuit to obtain a target test CAN signal for testing, and outputting the target test CAN signal to a CAN conversion box; the device thoroughly isolates the electric fast transient pulse group interference signals through the first communication isolation circuit and the second communication isolation circuit, improves the accuracy of testing CAN signals, and avoids influencing upper equipment such as a computer. The microcontroller performs further filtering processing on the possible interference signals on software, so as to ensure the correctness of the test CAN signals, then checks the received CAN signals, eliminates and removes false fidelity of data with obvious errors, so that the CAN signals CAN keep a real and effective part, and CAN also perform certain buffering on the received CAN signals, and perform repeated inquiry actions until the corresponding signals return to be correct after the lower level (such as a tested BMS) does not reply to the corresponding data. The accuracy of the CAN signal is ensured.
Further, the first communication isolation circuit and the second communication isolation circuit each include: the device comprises a voltage amplitude limiting sub-circuit, a filtering sub-circuit connected with the voltage amplitude limiting sub-circuit, an isolated CAN transceiver connected with the filtering sub-circuit and an RC filtering sub-circuit connected with the isolated CAN transceiver; the voltage limiting sub-circuit is used for carrying out differential mode filtering processing on the input CAN signal so as to limit the signal amplitude of the CAN signal below a set voltage; the filtering sub-circuit is used for performing voltage stabilizing filtering and high-frequency filtering on the CAN signal with the signal amplitude below the set voltage to obtain a voltage stabilizing low-frequency CAN signal; the isolated CAN transceiver is used for converting the stable low-frequency CAN signal into a TTL level signal; the RC filter sub-circuit is used for RC filtering the TTL level signal to obtain a test CAN signal which is output to the next stage. In this way, the common mode signal and the differential mode signal existing in the interference signal CAN be filtered through the voltage amplitude limiting sub-circuit, the energy of the interference signal is further reduced through the filtering sub-circuit, the differential mode interference signal is further filtered and the high-frequency interference signal is subjected to bypass filtering, so that no interference signal or fewer interference signals exist on the CAN signal of the isolated CAN transceiver. Further, the residual interference signals are subjected to bypass filtering again through the RC filter sub-circuit.
In addition, the CAN communication isolation device for resisting the pulse group is simple in operation, convenient in wiring and capable of being plugged and used at the same time, and the convenience of testing is improved.
In one embodiment, with continued reference to fig. 2, the voltage clipping sub-circuit 1001 includes:
a gas discharge tube TV1, a transient suppression diode D3 having a first end connected to a first pole of the gas discharge tube TV1, a transient suppression diode D4 having a first end connected to the first pole of the gas discharge tube TV1, and a transient suppression diode D5 having a first end connected to a second pole of the gas discharge tube TV 1;
wherein a second end of the transient suppression diode D3 is connected to the second pole of the gas discharge tube TV 1;
a second end of the transient suppression diode D4 and a second end of the transient suppression diode D5 are grounded;
the first pole of the gas discharge tube TV1 is configured as CANH input of the voltage limiter sub-circuit 1001, and the second pole of the gas discharge tube TV1 is configured as CANL input of the voltage limiter sub-circuit 1001;
a connection point of the first end of the transient suppression diode D3 and the first pole of the gas discharge tube TV1 is configured as a CANH output of the voltage clipping sub-circuit 1001, and a connection point of the second end of the transient suppression diode D3 and the second pole of the gas discharge tube TV1 is configured as a CANL output of the voltage clipping sub-circuit 1001.
In the embodiment of the disclosure, the gas discharge tube TV1 is 4532-091-LF, and the transient suppression diode D3, the transient suppression diode D4 and the transient suppression diode D5 are SMB7.5CA.
In the embodiment of the disclosure, the original test CAN signal may be filtered for the first time through the gas discharge tube TV1 in the first communication isolation circuit 101, a part of the interference signal is filtered, the interference signal with relatively high energy is mainly removed, the differential mode signal voltage amplitude in the interference signal is limited to below 9V, then the differential mode signal voltage amplitude is limited to below 7.5V through the filtering of the common mode signal and the differential mode signal existing in the interference signal, and the differential mode signal voltage amplitude is limited to below 7.5V through the next stage protection circuit formed by the TVs tube D4/D5/D6.
In one embodiment, with continued reference to fig. 2, the filtering sub-circuit 1002 includes:
resistor R2, resistor R6, resistor R4, electrostatic protection diode D1, common mode inductance L2, capacitor C10 and capacitor C11;
wherein a first end of the resistor R2 is configured as a CANH input of the filter sub-circuit 1002 and a first end of the resistor R6 is configured as a CANL input of the filter sub-circuit 1002;
the second end of the resistor R2 is connected with the No. 4 connecting end of the common-mode inductor L2, and the second end of the resistor R6 is connected with the No. 3 connecting end of the common-mode inductor L2;
the resistor R4 is connected between the No. 4 connection end of the common-mode inductor L2 and the No. 3 connection end of the common-mode inductor L2, a first end of the electrostatic protection diode D1 is connected with a CANH signal, a first end of the electrostatic protection diode D1 is connected with a CANL signal, and a third end of the electrostatic protection diode D1 is grounded;
the first end of the capacitor C10 is connected to the No. 1 connection end of the common-mode inductor L2 and configured as the CANH output end of the filter sub-circuit 1002 after connection, and the first end of the capacitor C11 is connected to the No. 2 connection end of the common-mode inductor L2 and configured as the CANL output end of the filter sub-circuit 1002 after connection.
In the embodiment of the disclosure, the resistor R2 and the resistor R6 are 9.1R, the resistor R4 is 120R, the electrostatic protection diode D1 is NUP2105L, the common-mode inductance L2 is ACT45B-101-2P-TL003, and the capacitor C10 and the capacitor C11 are both 12pF.
Along the description of the above embodiments, the CAN signal with the signal amplitude limited to 7.5V or less passes through the R2/R6 resistor, and according to ohm's law, i=v/R indicates that when the interference signal passes through the resistor, there is necessarily a current, and according to the energy consumption formula p=i×i×r of the resistor, the energy of the interference signal is further reduced by the resistor through heating. Then to the ESD zener diode D1, the differential mode interference signal reaching the remainder of the relatively energetic portion is further filtered out. And then the common-mode inductor L2 performs further prefabrication on the common-mode interference pulse signal, so that the filtering effect of the EMI is better. Finally, capacitors C10 and C11 bypass the remaining small portion of the high frequency interference signal arriving at this location, so that no or low interference signal is present on the CAN signal arriving at isolated CAN transceiver U1.
In one embodiment, with continued reference to fig. 2, the RC filter subcircuit 1003 includes:
the device comprises a resistor R3, a resistor R5, a capacitor C8 and a capacitor C9, wherein a first end of the resistor R3 is connected with a first end of the capacitor C8 and is connected with a TXD pin of the isolated CAN transceiver U1 after being connected, a second end of the capacitor C8 is grounded, and a second end of the resistor R3 is configured as a signal transmitting end of a communication isolation circuit and is used for outputting a test CAN signal to next-stage equipment;
the first end of the resistor R5 is connected with the first end of the capacitor C9 and is connected with the RXD pin of the isolated CAN transceiver U1 after being connected, the second end of the capacitor C9 is grounded, and the second end of the resistor R5 is configured as a signal receiving end of a communication isolation circuit and is used for receiving signals uploaded by next-stage equipment.
In the embodiment of the disclosure, the resistor R3 and the resistor R5 are both 10R, and the capacitor C8 and the capacitor C9 are both 47pF.
In the embodiment of the disclosure, RC filter circuits are added at the input/RX and output/TX ends of the isolated CAN transceiver U1 to bypass and filter interference signals, so that a certain protection effect is achieved.
In the embodiment of the disclosure, the isolated CAN transceiver U1 IS CA-IS3062W, and the first end of the capacitor C10 IS connected to the No. 1 connection end of the common-mode inductor L2, and configured after being connected, that the CANH output end of the filter sub-circuit 1002 IS connected to a CANH pin of CA-IS 3062W; the first end of the capacitor C11 IS connected to the No. 2 connection end of the common-mode inductor L2, and IS configured, after being connected, such that the CANL output end of the filter sub-circuit 1002 IS connected to a CANL pin of CA-IS 3062W. Further, the microcontroller 102 is NX5032GA, the second end of the resistor R3 in the first communication isolation circuit 101 is configured to connect the signal transmitting end of the communication isolation circuit with the PM1 pin of NX5032GA, and the second end of the resistor R5 in the first communication isolation circuit 101 is configured to connect the signal receiving end of the communication isolation circuit with the PM0 pin of NX5032 GA; the second end of the resistor R3 in the second communication isolation circuit 103 is configured to connect the signal transmitting end of the communication isolation circuit with the PM3 pin of NX5032GA, and the second end of the resistor R5 in the second communication isolation circuit 103 is configured to connect the signal receiving end of the communication isolation circuit with the PM2 pin of NX5032 GA. Referring to fig. 3, the specific connection relationship is shown, wherein U2 is the microcontroller 102.
In one embodiment, with continued reference to fig. 2, the first communication isolation circuit 101 and the second communication isolation circuit 103 each include: an LC power supply filter sub-circuit 1004, the LC power supply filter sub-circuit 1004 including an inductance L1, a capacitance C2, a capacitance C4, and a capacitance C6;
the first end of the inductor L1 is connected with a VCC5 power supply, the second end of the inductor L1 is connected with the capacitor C2, the capacitor C4 and the first end of the capacitor C6, and is connected with the power supply VCC1 of the isolated CAN transceiver U1 after being connected so as to provide a 5V direct current power supply for the isolated CAN transceiver U1;
the second ends of the capacitor C2, the capacitor C4 and the capacitor C6 are connected and grounded after being connected, and are connected with the first ground GND1 of the isolated CAN transceiver U1 after being connected.
In the embodiment of the disclosure, the inductance L1 is 1K, and the capacitance C2, the capacitance C4, and the capacitance C6 are all 100nF.
In one embodiment, with continued reference to fig. 2, the first communication isolation circuit 101 and the second communication isolation circuit 103 each include: a capacitive power supply filter sub-circuit 1005, the capacitive power supply filter sub-circuit 1005 comprising a capacitor C3, a capacitor C5, and a capacitor C7;
the first ends of the capacitor C3, the capacitor C5 and the capacitor C7 are connected together and respectively connected with a V5A power supply and a power supply VCC2 of the isolated CAN transceiver U1 after being connected so as to provide a 5V direct current power supply for the isolated CAN transceiver U1;
the second ends of the capacitor C3, the capacitor C5 and the capacitor C7 are connected together and connected to the second ground GND2 of the isolated CAN transceiver U1 after being connected.
In the embodiment of the disclosure, the capacitor C3, the capacitor C5 and the capacitor C7 are all 100nF.
The device isolates the input 5V power supply through the LC power supply filtering sub-circuit and the capacitor power supply filtering sub-circuit, ensures the stability of the power supply of the isolated CAN transceiver, and ensures the effectiveness of the isolation effect.
The device is connected to the CAN communication line between the BMS of the tested equipment and the CAN conversion box, and isolates the interference signal of the electric fast transient pulse group, so that the interference signal CAN not be transmitted to the CAN conversion box of the next stage, and the interference signal is isolated before the computer end, namely, the interference signal of the electric fast transient pulse group CAN not reach the computer end, thereby ensuring that the computer is not influenced, and finally ensuring that the upper computer CAN normally display the required measurement data.
Based on the same inventive concept, the embodiment of the present invention further provides a method for interference cancellation of a CAN communication isolation device based on an anti-pulse group, where the method is applied to the CAN communication isolation device 100 of an anti-pulse group in any one of the foregoing embodiments, as shown in fig. 4, and the method includes:
in step S31, the input CAN signal is subjected to differential mode filtering processing by a voltage limiting sub-circuit in the first communication isolation circuit, so as to limit the signal amplitude of the CAN signal below a set voltage;
in step S32, the voltage-stabilizing filtering and the high-frequency filtering are performed on the CAN signal with the signal amplitude below the set voltage by the filtering sub-circuit in the first communication isolation circuit, so as to obtain a voltage-stabilizing low-frequency CAN signal;
in step S33, the stable low-frequency CAN signal is converted into a TTL level signal by an isolated CAN transceiver in the first communication isolation circuit;
in step S34, the TTL level signal is RC filtered by an RC filter sub-circuit in the first communication isolation circuit, so as to obtain a pulse burst-free test CAN signal with the pulse burst interference filtered out;
in step S35, the microcontroller performs checksum and spurious elimination on the non-pulse-group test CAN signal to obtain an effective test CAN signal;
in step S36, the effective test CAN signal is subjected to secondary physical isolation and filtering by the second communication isolation circuit to obtain a target test CAN signal for testing, and the target test CAN signal is output to a CAN conversion box.
According to the technical scheme, the first communication isolation circuit is connected into the upper-level CAN communication device, so that the input test CAN signals CAN be physically isolated and filtered, and most pulse group interference signals CAN be removed. And then the MCU carries out deep processing on the received data, and interference is removed again on software, so that the data is real and effective. The microcontroller MCU performs second-stage physical isolation and anti-interference circuit on data through the second communication isolation circuit, transmits a target test CAN signal to next-stage communication equipment, ensures the validity of the data, completely filters out an electric fast transient pulse group interference signal in the test CAN signal, and avoids influencing the test of upper computer equipment such as a computer.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (7)
1. A CAN communication isolation device for resisting pulse groups, the device comprising:
the device comprises a first communication isolation circuit, a microcontroller connected with the output end of the first communication isolation circuit, and a second communication isolation circuit connected with the output end of the microcontroller;
the first communication isolation circuit is used for carrying out physical isolation and high-frequency filtering on an input original test CAN signal to obtain a pulse group-free test CAN signal with pulse group interference filtered;
the microcontroller is used for checking the pulse-burst-free test CAN signal and removing false fidelity to obtain an effective test CAN signal;
the second communication isolation circuit is used for carrying out secondary physical isolation and filtering on the effective test CAN signal to obtain a target test CAN signal for testing, and outputting the target test CAN signal to a CAN conversion box;
wherein, first communication isolation circuit and second communication isolation circuit all include: the device comprises a voltage amplitude limiting sub-circuit, a filtering sub-circuit connected with the voltage amplitude limiting sub-circuit, an isolated CAN transceiver connected with the filtering sub-circuit and an RC filtering sub-circuit connected with the isolated CAN transceiver;
the voltage amplitude limiting sub-circuit is used for carrying out differential mode filtering processing on an input CAN signal so as to limit the signal amplitude of the CAN signal below a set voltage;
the filter sub-circuit is used for performing voltage stabilizing filtering and high-frequency filtering on the CAN signal with the signal amplitude below the set voltage to obtain a voltage stabilizing low-frequency CAN signal;
the isolated CAN transceiver is used for converting the stable low-frequency CAN signal into a TTL level signal;
the RC filter sub-circuit is used for RC filtering the TTL level signal to obtain a test CAN signal which is output to the next stage.
2. The apparatus of claim 1, wherein the voltage clipping sub-circuit comprises:
a gas discharge tube TV1, a transient suppression diode D3 having a first end connected to a first pole of the gas discharge tube TV1, a transient suppression diode D4 having a first end connected to the first pole of the gas discharge tube TV1, and a transient suppression diode D5 having a first end connected to a second pole of the gas discharge tube TV 1;
wherein a second end of the transient suppression diode D3 is connected to the second pole of the gas discharge tube TV 1;
a second end of the transient suppression diode D4 and a second end of the transient suppression diode D5 are grounded;
the first pole of the gas discharge tube TV1 is configured as CANH input of the voltage clipping sub-circuit, and the second pole of the gas discharge tube TV1 is configured as CANL input of the voltage clipping sub-circuit;
the connection point of the first end of the transient suppression diode D3 with the first pole of the gas discharge tube TV1 is configured as CANH output of the voltage clipping sub-circuit, and the connection point of the second end of the transient suppression diode D3 with the second pole of the gas discharge tube TV1 is configured as CANL output of the voltage clipping sub-circuit.
3. The apparatus of claim 1, wherein the filtering sub-circuit comprises:
resistor R2, resistor R6, resistor R4, electrostatic protection diode D1, common mode inductance L2, capacitor C10 and capacitor C11;
wherein a first end of the resistor R2 is configured as a CANH input of the filter sub-circuit and a first end of the resistor R6 is configured as a CANL input of the filter sub-circuit;
the second end of the resistor R2 is connected with the No. 4 connecting end of the common-mode inductor L2, and the second end of the resistor R6 is connected with the No. 3 connecting end of the common-mode inductor L2;
the resistor R4 is connected between the No. 4 connection end of the common-mode inductor L2 and the No. 3 connection end of the common-mode inductor L2, a first end of the electrostatic protection diode D1 is connected with a CANH signal, a first end of the electrostatic protection diode D1 is connected with a CANL signal, and a third end of the electrostatic protection diode D1 is grounded;
the first end of the capacitor C10 is connected to the No. 1 connection end of the common-mode inductor L2 and configured as the CANH output end of the filter sub-circuit after connection, and the first end of the capacitor C11 is connected to the No. 2 connection end of the common-mode inductor L2 and configured as the CANL output end of the filter sub-circuit after connection.
4. The apparatus of claim 1, wherein the RC filter subcircuit comprises:
the device comprises a resistor R3, a resistor R5, a capacitor C8 and a capacitor C9, wherein a first end of the resistor R3 is connected with a first end of the capacitor C8 and is connected with a TXD pin of the isolated CAN transceiver after being connected, a second end of the capacitor C8 is grounded, and a second end of the resistor R3 is configured as a signal transmitting end of a communication isolated circuit and is used for outputting a test CAN signal to next-stage equipment;
the first end of the resistor R5 is connected with the first end of the capacitor C9 and is connected with the RXD pin of the isolated CAN transceiver after being connected, the second end of the capacitor C9 is grounded, and the second end of the resistor R5 is configured as a signal receiving end of a communication isolation circuit and is used for receiving signals uploaded by next-stage equipment.
5. The apparatus of any of claims 1-4, wherein the first communication isolation circuit and the second communication isolation circuit each comprise: the LC power supply filter sub-circuit comprises an inductor L1, a capacitor C2, a capacitor C4 and a capacitor C6;
the first end of the inductor L1 is connected with a VCC5 power supply, the second end of the inductor L1 is connected with the capacitor C2, the capacitor C4 and the first end of the capacitor C6, and is connected with the power supply VCC1 of the isolated CAN transceiver after being connected so as to provide a 5V direct current power supply for the isolated CAN transceiver;
the second ends of the capacitor C2, the capacitor C4 and the capacitor C6 are connected and grounded after being connected, and are connected with the first grounding end GND1 of the isolated CAN transceiver after being connected.
6. The apparatus of any of claims 1-4, wherein the first communication isolation circuit and the second communication isolation circuit each comprise: the capacitive power supply filter sub-circuit comprises a capacitor C3, a capacitor C5 and a capacitor C7;
the first ends of the capacitor C3, the capacitor C5 and the capacitor C7 are connected together and respectively connected with a V5A power supply and a power supply VCC2 of the isolated CAN transceiver after being connected so as to provide a 5V direct current power supply for the isolated CAN transceiver;
the second ends of the capacitor C3, the capacitor C5 and the capacitor 7 are connected together and connected to the second ground GND2 of the isolated CAN transceiver after being connected.
7. A method for interference cancellation of a CAN communication isolation device based on an anti-burst, wherein the method is applied to the CAN communication isolation device of an anti-burst according to any one of claims 1 to 6, the method comprising:
performing differential mode filtering processing on an input CAN signal through a voltage amplitude limiting sub-circuit in a first communication isolation circuit so as to limit the signal amplitude of the CAN signal below a set voltage;
the CAN signals with the signal amplitude below the set voltage are subjected to voltage stabilizing filtering and high-frequency filtering through a filtering sub-circuit in the first communication isolation circuit, so that voltage stabilizing low-frequency CAN signals are obtained;
converting the stable low-frequency CAN signal into a TTL level signal through an isolated CAN transceiver in the first communication isolation circuit;
RC filtering is carried out on the TTL level signal through an RC filtering sub-circuit in the first communication isolation circuit, so that a pulse group-free test CAN signal with pulse group interference filtered out is obtained;
checking and removing false fidelity of the pulse-burst-free test CAN signal through the microcontroller to obtain an effective test CAN signal;
and performing secondary physical isolation and filtering on the effective test CAN signal through a second communication isolation circuit to obtain a target test CAN signal for testing, and outputting the target test CAN signal to a CAN conversion box.
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