Impedance matching method and system for star-structured CAN bus

Abstract

The present invention discloses an impedance matching method for a star-structured CAN bus, comprising obtaining parameter information of a target star-structured CAN bus; measuring the loop impedance value of each branch on the target star-structured CAN bus; connecting a matching resistor to each branch of the target star-structured CAN bus; calculating the matching impedance value of the target star-structured CAN bus at the star node; and adding a matching impedance at the star node of the target star-structured CAN bus to complete the impedance matching of the target star-structured CAN bus. The present invention also discloses a system for implementing the impedance matching method for the star-structured CAN bus. The impedance matching method and system for the star-structured CAN bus provided by the present invention, by acquiring data and calculating impedance of the target CAN bus, not only achieve impedance matching of the star-structured CAN bus, but also have higher reliability, better accuracy, and higher efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of field buses, and in particular relates to an impedance matching method and system for a star-structured CAN bus. Background Art

[0002] With the development of economy and technology and the improvement of people's living standards, electricity has become an indispensable secondary energy source in people's production and life, bringing endless convenience to people's production and life. Therefore, ensuring a stable and reliable supply of electricity has become one of the most important tasks of the power system.

[0003] As environmental issues become increasingly severe, more and more renewable energy generation systems are being integrated into power systems to generate electricity. To address the operational pressures caused by the volatility and randomness of renewable energy generation systems, power systems are being connected to a large number of energy storage systems.

[0004] In current electrochemical energy storage systems, the battery management system master controller and slave controllers in the energy storage system generally use CAN bus for communication. Common CAN bus communication connection methods include Figure 1 As shown in the figure, this is a bus-shaped structure. In this method, the impedance matching solution is to connect a terminal resistor at the beginning and end of the bus to complete the impedance matching. However, this bus-shaped connection solution has the following problems: (1) The communication line is wired back and forth, making the communication loop wiring too long and inconvenient; (2) If a node in the loop exits, it will cause the bus loop to be interrupted; (3) When adding a device access point, it must be connected to the middle of the loop, which will increase the workload of wiring rectification.

[0005] Because of the above reasons, the star structure wiring method is gradually being adopted between the main controller and the slave controller of the battery management system. Figure 2 As shown in the figure, this wiring method improves the convenience of wiring, debugging, and operation and maintenance. However, there is still a problem: the star wiring method requires connecting a matching impedance (i.e., Figure 2 In addition, during the impedance adjustment process, the impedance values ​​of all matching impedances need to be adjusted synchronously, which is extremely cumbersome and inefficient. Summary of the Invention

[0006] One of the purposes of the present invention is to provide an impedance matching method for a star-structured CAN bus with high reliability, good accuracy and high efficiency.

[0007] A second object of the present invention is to provide a system for implementing the impedance matching method of the star-structured CAN bus.

[0008] The impedance matching method of the star-structured CAN bus provided by the present invention comprises the following steps:

[0009] S1. Obtain parameter information of the target star-shaped CAN bus;

[0010] S2. Measure the loop impedance of each branch of the target star-shaped CAN bus.

[0011] S3. Connect a matching resistor to each branch of the target star-shaped CAN bus, where the resistance of the matching resistor is the loop impedance value of the branch obtained in step S2;

[0012] S4. According to the impedance matching requirements of the target star structure CAN bus and the loop impedance value of each branch obtained in step S2, the matching impedance value of the target star structure CAN bus at the star node is calculated;

[0013] S5. At the star node of the target star-structured CAN bus, a matching impedance having an impedance value equal to the matching impedance value obtained in step S4 is added to complete the impedance matching of the target star-structured CAN bus.

[0014] The impedance matching method for the star-structured CAN bus further includes the following steps:

[0015] S6. When the target star-structure CAN bus needs to be impedance-matched again, repeat steps S1 to S5 to complete the impedance matching of the target star-structure CAN bus.

[0016] When the target star-structure CAN bus in step S5 needs to be impedance-matched again, the following steps are specifically included:

[0017] When the number of branches of the target star-structured CAN bus changes, impedance matching must be performed again.

[0018] The step S1 of obtaining the parameter information of the target star-structured CAN bus specifically includes the following steps:

[0019] Get the parameter information of the target star-structured CAN bus;

[0020] The parameter information includes the total number of loops and the impedance matching requirements of the target star-structured CAN bus.

[0021] The step S2 of measuring the loop impedance value of each branch on the target star-structured CAN bus specifically includes the following steps:

[0022] For each branch, the impedance value is measured using the following steps:

[0023] A. Disconnect all branches except the i-th branch from the target star-shaped CAN bus;

[0024] B. Measure the impedance value R of the i-th branch i ; The value of i ranges from 1 to N, where N is the total number of branches of the target star-structured CAN bus;

[0025] C. After the measurement is completed, all branches except the i-th branch are connected to the target star-structured CAN bus.

[0026] Step S4, according to the impedance matching requirements of the target star-structured CAN bus and the loop impedance value of each branch obtained in step S2, calculates the matching impedance value of the target star-structured CAN bus at the star node, specifically comprising the following steps:

[0027] The matching impedance value of the target star-structured CAN bus at the star node is calculated using the following formula:

[0028]

[0029] Where R j is the impedance value of the battery management system's total controller loop; R is the matching impedance value of the matching impedance to be added.

[0030] Step S5, at the star node of the target star-structured CAN bus, adds a matching impedance having an impedance value equal to the matching impedance value obtained in step S4 to complete the impedance matching of the target star-structured CAN bus, specifically comprising the following steps:

[0031] According to the calculation process of step S4, a matching impedance with an impedance value of R is added at the star node of the target star-structured CAN bus to complete the impedance matching of the target star-structured CAN bus.

[0032] The present invention also provides a system for implementing the impedance matching method of the star-structured CAN bus, comprising a data acquisition module, an impedance measurement module, a resistance access module, an impedance calculation module, an impedance matching module and a real-time matching module; the data acquisition module, the impedance measurement module, the resistance access module, the impedance calculation module, the impedance matching module and the real-time matching module are connected in series in sequence; the data acquisition module is used to acquire parameter information of the target star-structured CAN bus and upload the data information to the impedance measurement module; the impedance measurement module is used to measure the loop impedance value of each branch on the target star-structured CAN bus according to the received data information, and upload the data information to the resistance access module; the resistance access module is used to access a matching resistor in each branch of the target star-structured CAN bus according to the received data information, the resistance value of the matching resistor being the loop impedance value of the branch, and upload the data information to the Impedance calculation module; the impedance calculation module is used to calculate the matching impedance value of the target star structure CAN bus at the star node according to the received data information, the impedance matching requirements of the target star structure CAN bus and the loop impedance value of each branch, and upload the data information to the impedance matching module; the impedance matching module is used to add a matching impedance with an impedance value equal to the obtained matching impedance value at the star node of the target star structure CAN bus according to the received data information, complete the impedance matching of the target star structure CAN bus, and upload the data information to the real-time matching module; the real-time matching module is used to repeat the work of the data acquisition module, the impedance measurement module, the resistance access module, the impedance calculation module and the impedance matching module according to the received data information when the target star structure CAN bus needs to be re-impedance matched, so as to complete the impedance matching of the target star structure CAN bus.

[0033] The impedance matching method and system for the star-structured CAN bus provided by the present invention not only achieves impedance matching of the star-structured CAN bus by acquiring data of the target CAN bus and calculating the impedance, but also has higher reliability, better accuracy and higher efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The figure is a schematic diagram of the connection mode of the existing bus-shaped CAN bus.

[0035] Figure 2 The figure is a schematic diagram of the connection mode of the existing star-structured CAN bus.

[0036] Figure 3 Schematic diagram of the process of the present invention.

[0037] Figure 4 Schematic diagram of impedance matching of the method of the present invention.

[0038] Figure 5Schematic diagram of the functional modules of the system of the present invention. DETAILED DESCRIPTION

[0039] like Figure 3 The figure shows a flow chart of the method of the present invention: the impedance matching method of the star-structured CAN bus disclosed in the present invention comprises the following steps:

[0040] S1. Obtain parameter information of the target star-shaped CAN bus; specifically, the steps include:

[0041] Get the parameter information of the target star-structured CAN bus;

[0042] The parameter information includes the total number of loops and the impedance matching requirements of the target star-structured CAN bus;

[0043] S2. Measure the loop impedance of each branch of the target star-shaped CAN bus. This includes the following steps:

[0044] For each branch, the impedance value is measured using the following steps:

[0045] A. Disconnect all branches except the i-th branch from the target star-shaped CAN bus;

[0046] B. Measure the impedance value R of the i-th branch i ; The value of i ranges from 1 to N, where N is the total number of branches of the target star-structured CAN bus;

[0047] C. After the measurement is completed, all branches except the i-th branch are connected to the target star-shaped CAN bus;

[0048] S3. Connect a matching resistor to each branch of the target star-shaped CAN bus, where the resistance of the matching resistor is the loop impedance value of the branch obtained in step S2;

[0049] S4. According to the impedance matching requirements of the target star structure CAN bus and the loop impedance value of each branch obtained in step S2, the matching impedance value of the target star structure CAN bus at the star node is calculated; specifically comprising the following steps:

[0050] The matching impedance value of the target star-structured CAN bus at the star node is calculated using the following formula:

[0051]

[0052] Where R j is the impedance value of the battery management system's total controller loop; R is the matching impedance value of the matching impedance to be added;

[0053] S5. At the star node of the target star structure CAN bus, increase the impedance value to the matching impedance value obtained in step S4 to complete the impedance matching of the target star structure CAN bus; specifically comprising the following steps:

[0054] According to the calculation process of step S4, a matching impedance with an impedance value of R is added at the star node of the target star-structured CAN bus to complete the impedance matching of the target star-structured CAN bus, as shown in FIG. Figure 4 As shown;

[0055] S6. When the impedance matching of the target star-shaped CAN bus needs to be re-performed, repeat steps S1 to S5 to complete the impedance matching of the target star-shaped CAN bus;

[0056] In a specific implementation, when the target star-structured CAN bus needs to be impedance-matched again, the following steps are specifically included:

[0057] When the number of branches of the target star-structured CAN bus changes, impedance matching must be performed again;

[0058] In specific implementation, for example, if a certain loop is directly exited or a loop is added to the target star-structured CAN bus, impedance matching needs to be re-performed.

[0059] like Figure 5The figure shows a functional module diagram of the system of the present invention: the system disclosed in the present invention for realizing the impedance matching method of the star-structured CAN bus comprises a data acquisition module, an impedance measurement module, a resistance access module, an impedance calculation module, an impedance matching module and a real-time matching module; the data acquisition module, the impedance measurement module, the resistance access module, the impedance calculation module, the impedance matching module and the real-time matching module are connected in series in sequence; the data acquisition module is used to acquire parameter information of the target star-structured CAN bus and upload the data information to the impedance measurement module; the impedance measurement module is used to measure the loop impedance value of each branch on the target star-structured CAN bus according to the received data information, and upload the data information to the resistance access module; the resistance access module is used to access a matching resistor in each branch of the target star-structured CAN bus according to the received data information, and the resistance value of the matching resistor is the loop impedance value of the branch, And upload the data information to the impedance calculation module; the impedance calculation module is used to calculate the matching impedance value of the target star structure CAN bus at the star node according to the received data information, the impedance matching requirements of the target star structure CAN bus and the loop impedance value of each branch, and upload the data information to the impedance matching module; the impedance matching module is used to increase the matching impedance value of the obtained matching impedance value at the star node of the target star structure CAN bus according to the received data information, complete the impedance matching of the target star structure CAN bus, and upload the data information to the real-time matching module; the real-time matching module is used to repeat the work of the data acquisition module, the impedance measurement module, the resistance access module, the impedance calculation module and the impedance matching module according to the received data information when the target star structure CAN bus needs to be re-impedance matched, so as to complete the impedance matching of the target star structure CAN bus.

[0060] In specific implementation, when measuring the impedance value of each branch, a controllable switch can be added to the connecting line of each branch; when measuring the impedance value of the branch, all controllable switches except the controllable switch of the branch are disconnected to ensure that the measured impedance value is the impedance value of the branch.

[0061] The controllable switch can be turned on and off by a master controller.

[0062] In order to facilitate the real-time impedance matching of the target star-structured CAN bus, a preferred solution is: Figure 2 As shown, an adjustable resistor is connected in parallel at the star node of the target star-structured CAN bus. The adjustable resistor is the additional matching impedance. When performing real-time matching of the bus impedance, the resistance value of the adjustable resistor is dynamically adjusted to achieve real-time matching of the bus impedance.

Claims

1. An impedance matching method for a star-structured CAN bus, comprising the following steps: S1. Obtain parameter information of the target star-shaped CAN bus; S2. Measure the loop impedance of each branch of the target star-shaped CAN bus. This includes the following steps: For each branch, the impedance value is measured using the following steps: A. Disconnect all branches except the i-th branch from the target star-shaped CAN bus; B. Measure the impedance value R of the i-th branch i ; The value of i ranges from 1 to N, where N is the total number of branches of the target star-structured CAN bus; C. After the measurement is completed, all branches except the i-th branch are connected to the target star-shaped CAN bus; S3. Connect a matching resistor to each branch of the target star-shaped CAN bus, where the resistance of the matching resistor is the loop impedance value of the branch obtained in step S2; S4. According to the impedance matching requirements of the target star structure CAN bus and the loop impedance value of each branch obtained in step S2, the matching impedance value of the target star structure CAN bus at the star node is calculated; specifically comprising the following steps: The matching impedance value of the target star-structured CAN bus at the star node is calculated using the following formula: Where R j is the impedance value of the battery management system's total controller loop; R is the matching impedance value of the matching impedance to be added; S5. At the star node of the target star-structured CAN bus, a matching impedance having an impedance value equal to the matching impedance value obtained in step S4 is added to complete the impedance matching of the target star-structured CAN bus.

2. The impedance matching method for a star-structured CAN bus according to claim 1, characterized in that The following steps are also included: S6. When the target star-structure CAN bus needs to be impedance-matched again, repeat steps S1 to S5 to complete the impedance matching of the target star-structure CAN bus.

3. The impedance matching method of the star-structured CAN bus according to claim 2, characterized in that When the target star-structure CAN bus in step S5 needs to be impedance-matched again, the following steps are specifically included: When the number of branches of the target star-structured CAN bus changes, impedance matching must be performed again.

4. The impedance matching method for a star-structured CAN bus according to claim 3, characterized in that The step S1 of obtaining the parameter information of the target star-structured CAN bus specifically includes the following steps: Get the parameter information of the target star-structured CAN bus; The parameter information includes the total number of loops and the impedance matching requirements of the target star-structured CAN bus.

5. The impedance matching method of the star-structured CAN bus according to claim 1, characterized in that Step S5, at the star node of the target star-structured CAN bus, adds a matching impedance having an impedance value equal to the matching impedance value obtained in step S4 to complete the impedance matching of the target star-structured CAN bus, specifically comprising the following steps: According to the calculation process of step S4, a matching impedance with an impedance value of R is added at the star node of the target star-structured CAN bus to complete the impedance matching of the target star-structured CAN bus.

6. A system for implementing the impedance matching method of a star-structured CAN bus according to any one of claims 1 to 5, characterized in that It includes a data acquisition module, an impedance measurement module, a resistance access module, an impedance calculation module, an impedance matching module and a real-time matching module; the data acquisition module, the impedance measurement module, the resistance access module, the impedance calculation module, the impedance matching module and the real-time matching module are connected in series in sequence; the data acquisition module is used to obtain parameter information of the target star-structure CAN bus and upload the data information to the impedance measurement module; the impedance measurement module is used to measure the loop impedance value of each branch on the target star-structure CAN bus according to the received data information, and upload the data information to the resistance access module; The resistor access module is used to access a matching resistor in each branch of the target star-structured CAN bus according to the received data information, wherein the resistance of the matching resistor is the loop impedance value of the branch, and upload the data information to the impedance calculation module; the impedance calculation module is used to calculate the matching impedance value of the target star-structured CAN bus at the star node according to the received data information, the impedance matching requirements of the target star-structured CAN bus and the loop impedance value of each branch, and upload the data information to the impedance matching module; The impedance matching module is used to increase the matching impedance of the target star-structured CAN bus at the star node according to the received data information, thereby completing the impedance matching of the target star-structured CAN bus and uploading the data information to the real-time matching module; The real-time matching module is used to repeat the work of the data acquisition module, impedance measurement module, resistance access module, impedance calculation module and impedance matching module according to the received data information when the target star-structure CAN bus needs to be re-impedance matched, so as to complete the impedance matching of the target star-structure CAN bus.

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