RS485 communication isolation protection circuit based on electric bicycle BMS

Abstract

The utility model relates to an RS485 communication isolation protection circuit based on an electric bicycle BMS. The RS485 communication isolation protection circuit comprises a UART-to-RS485 module and an RS485 communication module, wherein the UART-to-RS485 module and the RS485 communication module are electrically connected with each other. The communication end and the signal control end of the UART-to-RS485 module are connected with the single chip microcomputer main control module, and the power supply ends of the UART-to-RS485 module and the RS485 communication module are connected with the BMS system power supply module; according to the RS485 communication isolation protection circuit provided by the utility model, a communication isolation chip and a control isolation chip can be omitted, so that the circuit cost is effectively reduced; and the RS485 communication module adopts an MOS (Metal Oxide Semiconductor) tube isolation mode, so that a communication circuit can be effectively protected from being burnt out.

Description

Technical Field

[0001] This utility model relates to the field of communication isolation protection circuit technology, specifically to an RS485 communication isolation protection circuit based on an electric bicycle BMS. Background Technology

[0002] With the increasing popularity of electric bicycles, the RS485 communication interface, as a communication standard between electric bicycles and key components such as batteries and control systems, is widely used in battery management systems (BMS) and various monitoring and control circuits of electric bicycles. While the RS485 communication protocol has advantages such as strong anti-interference capabilities and long transmission distances, in actual use, especially when the battery and electric bicycle connection is poor, communication circuit damage can easily occur.

[0003] Currently, to protect RS485 communication circuits from voltage surges and poor communication connections, traditional solutions typically employ power isolation modules to isolate the power supply to the RS485 communication chip, preventing voltage fluctuations from directly affecting its normal operation. Common isolation schemes use DC-DC power isolation modules, which utilize DC-DC step-down chips, isolation transformers, optocouplers, and other isolation components to achieve power and signal isolation for the RS485 communication circuit.

[0004] Specifically, the existing solution for RS485 communication isolation schemes adopts the following... Figure 1 The DC-DC isolated power supply scheme shown is as follows: First, a DC-DC step-down chip (VU1) is used in conjunction with an inductor (VL1), capacitors (VC24, V16, etc.), and external components to step down the battery voltage. Then, a DC-DC isolated power supply chip (VU2) and an isolation transformer (VT1) are used to isolate the voltage. Finally, the voltage is stepped down to the power supply voltage adapted to the RS485 chip (XU1) through rectifier diodes (VD7, VD9). The MCU needs to isolate the data sent by the MCU through the isolation communication chip (XU12) before connecting to the RS485 chip (XU1). The MCU control signal needs to be isolated through the optocoupler (XU11) before controlling the RS485 chip (XU1).

[0005] The above solution has the following obvious shortcomings:

[0006] High power consumption: Traditional DC-DC buck circuits require additional power to drive them. In addition, due to the dual isolation of power supply and signal, the overall power consumption is high, which increases the energy consumption of the system.

[0007] Complex circuitry and high cost: To achieve effective power and signal isolation, multiple isolation components must be used, such as DC-DC power modules, isolation transformers, optocouplers, and isolation chips. The complex circuit structure and large number of components lead to increased material costs.

[0008] Large footprint: The isolation power supply module and other related circuits require a large area of ​​board space, which increases the difficulty of design and production.

[0009] Electromagnetic interference (EMI) issues: Electromagnetic interference can be easily introduced during the isolation of power supplies and signal processing, especially in high-power electric bicycle systems, where EMI may exceed industry standards and affect communication quality.

[0010] Therefore, while existing power and signal isolation solutions are effective, there is still significant room for improvement in reducing system power consumption, simplifying circuits, reducing material costs, and minimizing electromagnetic interference. To address these issues, a new RS485 communication isolation and protection solution is urgently needed. This solution should effectively prevent damage to the communication circuit caused by poor battery-electric bicycle interface connections, while also reducing system power consumption, simplifying circuit design, reducing material costs, and effectively resolving electromagnetic interference problems. Utility Model Content

[0011] The purpose of this utility model is to provide an RS485 communication isolation protection circuit based on an electric bicycle BMS, so as to solve at least one technical problem in the prior art.

[0012] The technical solution provided by this utility model is as follows:

[0013] An RS485 communication isolation protection circuit based on an electric bicycle BMS, the RS485 communication isolation protection circuit includes a UART to RS485 module and an RS485 communication module that are electrically connected to each other;

[0014] The communication end and signal control end of the UART to RS485 module are connected to the microcontroller main control module, and the power supply end of the UART to RS485 module is connected to the BMS system power supply module.

[0015] The RS485 communication module includes an RS485-B line low-voltage shutdown module, an RS485-A line low-voltage shutdown module, and an RS485 high-voltage shutdown module. The power supply terminals of the RS485-B line low-voltage shutdown module and the RS485-A line low-voltage shutdown module are all connected to the BMS system power supply module. The RS485-B line low-voltage shutdown module, the RS485-A line low-voltage shutdown module, and the RS485 high-voltage shutdown module are all connected to the RS485 communication interface of the electric bicycle.

[0016] Preferably, both the RS485-B line low-voltage shutdown module and the RS485-A line low-voltage shutdown module include a first power supply module, a first switch module, a second switch module, and a low-voltage switch control module connected to the first power supply module. The voltage input terminal of the first power supply module is connected to the BMS system power supply module as a power supply terminal, and the voltage output terminal of the first power supply module is connected to the RS485 high-voltage shutdown module through a first diode. The first switch module is connected to the UART to RS485 module, the second switch module is connected to the RS485 communication interface of the electric bicycle, and the low-voltage switch control module is connected to both the first switch module and the second switch module.

[0017] Furthermore, a voltage regulation and protection module is connected between the second switch module and the RS485 communication interface of the electric bicycle. The voltage regulation and protection module includes a first voltage regulator diode, the anode of which is grounded and the cathode of which is connected to the RS485 communication interface of the electric bicycle.

[0018] Preferably, a resistor and / or capacitor are connected in parallel between the anode and cathode of the first Zener diode.

[0019] Preferably, the first switching module includes a first MOSFET, the second switching module includes a second MOSFET, the drain of the first MOSFET is connected to the UART to RS485 module, the source of the first MOSFET is connected to the source of the second MOSFET, the gates of both the first and second MOSFETs are connected to the voltage output terminal of the first power module, and the drain of the second MOSFET is connected to the RS485 communication interface of the electric bicycle.

[0020] Preferably, the low-voltage switch control module includes a first transistor, the collector of which is connected to the voltage output terminal of the first power module through a resistor, the base of which is grounded through a resistor and a second diode, the anode of which is grounded, the cathode of which is connected to the base of the first transistor through a resistor, the emitter of which is connected to the source of the first MOSFET and the source of the second MOSFET, and the emitter of which is connected to the base of the first transistor through a resistor.

[0021] Preferably, the RS485 high-voltage shutdown module includes a second transistor. The base of the second transistor is connected to the RS485 communication interface of the electric bicycle through a resistor and a second Zener diode. A diode is connected between the RS485 communication interface of the electric bicycle and the second Zener diode. The collector of the second transistor is connected to the cathode of the first diode in the RS485 communication module, and the emitter of the second transistor is grounded. Preferably, a resistor and / or capacitor are connected in parallel between the emitter and base of the second transistor.

[0022] Compared with the prior art, the RS485 communication isolation protection circuit provided by this utility model has the following beneficial effects:

[0023] (1) The RS485 communication isolation protection circuit provided by this utility model directly uses the BMS system for power supply, without the need for a separate power supply module or a DC-DC step-down circuit. Therefore, it can effectively reduce the circuit cost. At the same time, the microcontroller main control module is directly connected to the UART to RS485 module (the microcontroller chip and the RS485 chip are directly connected). The communication end and signal control end of the ART to RS485 module are connected to the microcontroller main control module. Therefore, the communication signal and the control signal do not need to be isolated. Thus, the communication isolation chip and the control isolation chip can be eliminated, thereby effectively reducing the circuit cost.

[0024] (2) The RS485 communication isolation protection circuit provided by this utility model adopts the MOS tube isolation mode. When the connection between the battery and the RS485 communication interface of the electric bicycle is disconnected, the connection can be determined by detecting the level change of the RS485 communication interface. If the connection is disconnected, the connection between the battery and the RS485 communication interface of the electric bicycle is turned off, thereby effectively protecting the communication circuit from burning out. Attached Figure Description

[0025] Figure 1 This refers to the RS485 communication isolation circuit based on the BMS of an electric bicycle in the existing technology;

[0026] Figure 2 This is a schematic block diagram of the RS485 communication isolation protection circuit described in this embodiment of the present invention;

[0027] Figure 3 This is a detailed circuit diagram of the RS485 communication isolation protection circuit described in this embodiment of the present invention;

[0028] Figure 4 This is a detailed circuit diagram of the UART to RS485 module described in this embodiment of the present invention;

[0029] Figure 5 This is a detailed circuit diagram of the RS485-B line low-voltage shutdown module described in this embodiment of the present invention;

[0030] Figure 6 This is a detailed circuit diagram of the RS485-A line low-voltage shutdown module described in this embodiment of the present invention;

[0031] Figure 7 This is a detailed circuit diagram of the RS485 high-voltage shutdown module described in this embodiment of the present invention;

[0032] Figure 8 This is a detailed circuit diagram of the RS485-B line low-voltage shutdown module described in this embodiment of the present invention;

[0033] Figure 9 This is a detailed circuit diagram of the RS485 high-voltage shutdown module described in this embodiment of the present invention.

[0034] The reference numerals are as follows: 10. UART to RS485 module; 20. RS485-B line low-voltage shutdown module; 21. First power supply module; 22. First switch module; 23. Second switch module; 24. Low-voltage switch control module; 25. Voltage regulation protection module; 30. RS485-A line low-voltage shutdown module; 40. First diode XD9. Detailed Implementation

[0035] To better understand the purpose, technical solution, and technical effects of this utility model, the following description, in conjunction with the accompanying drawings and embodiments, will provide further explanation. It should also be stated that the embodiments described below are for illustrative purposes only and are not intended to limit the scope of this utility model.

[0036] Example 1

[0037] like Figure 2-9 As shown, an RS485 communication isolation protection circuit based on an electric bicycle BMS is provided. The RS485 communication isolation protection circuit includes a UART to RS485 module 20 and an RS485 communication module that are electrically connected to each other.

[0038] The communication end and signal control end of the UART to RS485 module are connected to the microcontroller main control module, and the power supply end of the UART to RS485 module is connected to the BMS system power supply module.

[0039] The RS485 communication module includes an RS485-B line low-voltage shutdown module 20, an RS485-A line low-voltage shutdown module 30, and an RS485 high-voltage shutdown module 40. The power supply terminals of the RS485-B line low-voltage shutdown module 20 and the RS485-A line low-voltage shutdown module 30 are all connected to the BMS system power supply module. The RS485-B line low-voltage shutdown module 20, the RS485-A line low-voltage shutdown module 30, and the RS485 high-voltage shutdown module 40 are all connected to the RS485 communication interface of the electric bicycle.

[0040] In this embodiment, the power supply terminals of both the UART to RS485 module and the RS485 communication module are directly connected to the BMS system power supply module, eliminating the need for a separate power supply module and a DC-DC step-down circuit. This effectively reduces circuit efficiency. Furthermore, the communication and signal control terminals of the UART to RS485 module are connected to the microcontroller main control module, so communication and control signals do not need isolation. This eliminates the need for separate communication and control isolation chips, thereby significantly reducing circuit costs. Specifically, the 3.3V voltage in the UART to RS485 module is provided by the BMS system power supply module, and the voltage VCC1 of the RS485-B line low-voltage shutdown module 20 and the RS485-A line low-voltage shutdown module 30 of the RS485 communication module is also provided by the BMS system power supply module.

[0041] In one specific implementation, the specific circuit structure of the UART to RS485 module is shown in the attached figure. Figure 4 As shown, details will not be elaborated here. Among them, the appendix... Figure 4 The chip with the designation XU13 is an RS485 chip.

[0042] In one preferred embodiment, both the RS485-B line low-voltage shutdown module 20 and the RS485-A line low-voltage shutdown module 30 include a first power supply module, a first switch module, a second switch module, and a low-voltage switch control module connected to the first power supply module. The voltage input terminal of the first power supply module is connected to the BMS system power supply module as a power supply terminal, and the voltage output terminal of the first power supply module is connected to the RS485 high-voltage shutdown module 40 through a first diode. The first switch module is connected to the UART to RS485 module, and the second switch module is connected to the electric bicycle RS485 communication interface. The low-voltage switch control module is connected to both the first and second switch modules. Further, a voltage regulation protection module is connected between the second switch module and the electric bicycle RS485 communication interface. The voltage regulation protection module includes a first Zener diode, with its anode grounded and its cathode connected to the electric bicycle RS485 communication interface. Preferably, a resistor and / or capacitor are connected in parallel between the anode and cathode of the first Zener diode.

[0043] In this embodiment, the RS485-B line low-voltage shutdown module 20 and the RS485-A line low-voltage shutdown module 30 have the same circuit composition and circuit structure, as shown in the attached figure. Figure 3 , Figure 5 and Figure 6 As shown.

[0044] The following explanation uses the RS485-B line low-voltage shutdown module 20 as an example: Figure 8As shown, the RS485-B line low-voltage shutdown module 20 includes a first power module 21, a first switch module 22, a second switch module 23, and a low-voltage switch control module 24, all connected to the first power module. The voltage input terminal of the first power module is connected to the BMS system power supply module as a power supply terminal, and the voltage output terminal of the first power module is connected to the RS485 high-voltage shutdown module 40 through a first diode XD9. The first switch module is connected to the UART to RS485 module, and the second switch module is connected to the electric bicycle RS485 communication interface. The low-voltage switch control module is connected to both the first and second switch modules. Preferably, a voltage stabilization protection module 25 is connected between the second switch module and the electric bicycle RS485 communication interface.

[0045] Specifically, as shown in the attached document Figure 8 As shown, the first switching module 22 includes a first MOSFET XM2, and the second switching module 23 includes a second MOSFET XM4. The drain of the first MOSFET XM2 is connected to the UART to RS485 module, the source of the first MOSFET XM2 is connected to the source of the second MOSFET XM4, the gates of both the first MOSFET XM2 and the second MOSFET XM4 are connected to the voltage output terminal of the first power module, and the drain of the second MOSFET XM4 is connected to the RS485 communication interface of the electric bicycle.

[0046] Specifically, as shown in the attached document Figure 8 As shown, the low-voltage switch control module includes a first transistor XQ1. The collector of the first transistor XQ1 is connected to the voltage output terminal of the first power module 21 through a resistor XR19. The base of the first transistor XQ1 is grounded through a resistor XR26 and a second diode XD5. The anode of the second diode XD5 is grounded, and the cathode of the second diode is connected to the base of the first transistor XQ1 through a resistor XR26. The emitter of the first transistor XQ1 is connected to the source of the first MOSFET XM2 and the source of the second MOSFET XM4. The emitter of the first transistor XQ1 is connected to the base of the first transistor XQ1 through a resistor XR22.

[0047] Specifically, as shown in the attached document Figure 9As shown, the RS485 high-voltage shutdown module 40 includes a second transistor XQ4. The base of the second transistor is connected to the RS485 communication interface of the electric bicycle through a resistor XR34 and a second Zener diode XZ7. A diode (specifically diode XD11 and diode XD12) is connected between the RS485 communication interface of the electric bicycle and the second Zener diode XZ7. The collector of the second transistor XQ4 is connected to the cathode of the first diode XD9 in the RS485 communication module, and the emitter of the second transistor XQ4 is grounded. A resistor XR32 and a capacitor XC3 are connected in parallel between the emitter and base of the second transistor XQ4.

[0048] The RS485 communication isolation protection circuit provided by this utility model uses a MOS transistor isolation mode for the RS485 communication module. When the connection between the battery and the RS485 communication interface of the electric bicycle is disconnected, the connection can be determined by detecting the level change of the RS485 communication interface. If the connection is disconnected, the connection between the battery and the RS485 communication interface of the electric bicycle is turned off, thereby effectively protecting the communication circuit from being burned out.

[0049] The following is a brief description of the working process or working principle of the RS485 communication module provided in this embodiment:

[0050] When the battery is disconnected from the RS485 communication interface of the electric bicycle, the RS485 high voltage shutdown module 40 can detect the level change of the RS485 communication interface of the electric bicycle to determine whether the connection is disconnected. If the connection is disconnected, the connection between the battery and the RS485 communication interface of the electric bicycle will be shut off, thereby effectively protecting the communication circuit from being burned out.

[0051] Details are as attached Figure 3 - Appendix Figure 9 As shown, when the battery is disconnected from the electric bicycle's RS485 communication interface:

[0052] If the communication port voltage (the voltages at the terminals labeled 485-B and 485-A in the attached diagram are the communication port voltages) is lower than the operating ground voltage of the RS485 chip in the UART to RS485 module (the one labeled XU13 in the attached diagram is the RS485 chip), as shown in the attached diagram... Figure 5 As shown, at this time, the low-voltage switch control module 20 of the RS485-B line low-voltage shutdown module controls the switching state of the first transistor XQ1 through the second diode XD5, causing the gate and source terminals of the first MOSFET XM2 and the second MOSFET XM4 to be short-circuited, thereby shutting down the RS485 communication circuit. (Appendix) Figure 2 In the diagram, the loop formed between labels 485-B1 and 485-B and labels 485-A1 and 485-A is the RS485 communication loop.

[0053] If the communication port voltage is higher than the operating power supply voltage of the RS485 chip, the voltage of the electric bicycle's RS485 communication interface will be controlled by diodes XD11 and XD12 in the RS485 high voltage shutdown module, and then by the second Zener diode XZ7. This will turn on the second transistor XQ4, thereby pulling the power supply of the first MOSFET XM2 and the second MOSFET down to the ground, thus shutting down the RS485 communication circuit and providing high voltage protection.

[0054] If the communication port voltage is within the operating voltage range of the RS485 chip, the circuit is connected.

[0055] The above embodiments only illustrate several implementation methods of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A BMS-based RS485 communication isolation protection circuit for electric bicycles, characterized in that, The RS485 communication isolation protection circuit comprises a UART-to-RS485 module and an RS485 communication module which are electrically connected with each other. The communication end and the signal control end of the UART-to-RS485 module are connected with a single-chip microcomputer master control module, and the power supply end of the UART-to-RS485 module is connected with a BMS system power supply module. The RS485 communication module comprises an RS485-B line low-voltage shutdown module, an RS485-A line low-voltage shutdown module and an RS485 high-voltage shutdown module, the power supply ends of the RS485-B line low-voltage shutdown module and the RS485-A line low-voltage shutdown module are connected with the BMS system power supply module, and the RS485-B line low-voltage shutdown module, the RS485-A line low-voltage shutdown module and the RS485 high-voltage shutdown module are connected with an electric bicycle RS485 communication interface.

2. The RS485 communication isolation protection circuit according to claim 1, characterized in that, The RS485-B line low-voltage shutdown module and the RS485-A line low-voltage shutdown module each comprise a first power supply module, a first switch module, a second switch module and a low-voltage switch control module which are connected with the first power supply module, the voltage input end of the first power supply module is connected with the BMS system power supply module as the power supply end, the voltage output end of the first power supply module is connected with the RS485 high-voltage shutdown module through a first diode, the first switch module is connected with the UART-to-RS485 module, the second switch module is connected with the electric bicycle RS485 communication interface, and the low-voltage switch control module is connected with the first switch module and the second switch module.

3. The RS485 communication isolation protection circuit according to claim 2, characterized in that, A voltage stabilizing protection module is connected between the second switch module and the electric bicycle RS485 communication interface.

4. The RS485 communication isolation protection circuit according to claim 2, characterized in that, The first switch module comprises a first MOS tube, the second switch module comprises a second MOS tube, the drain of the first MOS tube is connected with the UART-to-RS485 module, the source of the first MOS tube is connected with the source of the second MOS tube, the gates of the first MOS tube and the second MOS tube are connected with the voltage output end of the first power supply module, and the drain of the second MOS tube is connected with the electric bicycle RS485 communication interface.

5. The RS485 communication isolation protection circuit according to claim 4, characterized in that, The low-voltage switch control module comprises a first triode, the collector of the first triode is connected with the voltage output end of the first power supply module through a resistor, the base of the first triode is grounded through a resistor and a second diode, the anode of the second diode is grounded, the cathode of the second diode is connected with the base of the first triode through a resistor, the emitter of the first triode is connected with the source of the first MOS tube and the source of the second MOS tube, and the emitter of the first triode is connected with the base of the first triode through a resistor.

6. The RS485 communication isolation protection circuit according to claim 3, characterized in that, The voltage stabilizing protection module comprises a first voltage stabilizing tube, the anode of the first voltage stabilizing tube is grounded, and the cathode of the first voltage stabilizing tube is connected with the electric bicycle RS485 communication interface.

7. The RS485 communication isolation protection circuit according to claim 6, characterized in that, A resistor and / or a capacitor are connected in parallel between the anode and the cathode of the first voltage stabilizing tube.

8. The RS485 communication isolation protection circuit according to claim 6, characterized in that, The RS485 high-voltage shutdown module comprises a second triode, a base of the second triode is connected with the electric bicycle RS485 communication interface through a resistor and a second stabilizing tube, a diode is connected between the electric bicycle RS485 communication interface and the second stabilizing tube, a collector of the second triode is connected with a cathode of a first diode in the RS485 communication module, and an emitter of the second triode is grounded.

9. The RS485 communication isolation protection circuit according to claim 8, characterized in that, A resistor and / or a capacitor are connected in parallel between the emitter and the base of the second triode.

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