Signal transmission method and signal transmission device for low-voltage electric vehicle

Abstract

The invention relates to the technical field of electric vehicle signal transmission, in particular to a signal transmission method and device for a low-voltage electric vehicle, and the method comprises the steps: generating a communication signal to be transmitted to an instrument in a motor driver, modulating the communication signal to a carrier wave, and forming a modulation signal; according to the method, the chopping time sequence of the power switch in the motor driver is obtained, the signal sending time period is selected according to the chopping time sequence, and finally, the modulation signal is coupled to the complete closed-loop process of the power battery power supply wire of the electric vehicle in the signal sending time period, so that stable and low-cost one-way signal transmission between the motor driver and the instrument can be realized.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle signal transmission technology, and in particular to a signal transmission method and signal transmission device for low-voltage electric vehicles. Background Technology

[0002] Currently, the battery voltage of low-voltage electric vehicles (such as forklifts, golf carts, and sightseeing vehicles) is typically between 12V and 144V. Their motor drivers generally use MOSFETs for chopper-driven operation, outputting a sinusoidal current, with the voltage signal being a square wave with a carrier wave (5kHz~15kHz). In existing technology, communication between the motor driver and the instrument panel typically uses CAN or RS-485 bus. This communication method is basically unidirectional (from driver to instrument panel), with a low communication rate (approximately 120bps to 2400bps), and requires additional communication wiring, increasing system complexity and cost. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a signal transmission method and signal transmission device for low-voltage electric vehicles, which can realize stable and low-cost unidirectional signal transmission between the motor driver and the instrument.

[0004] To solve the above-mentioned technical problems, the first technical solution adopted by the present invention is as follows:

[0005] A signal transmission method for low-voltage electric vehicles includes the following steps: S1. Generate a communication signal to be sent to the instrument inside the motor driver of the electric vehicle; S2. Modulate the communication signal onto a carrier wave to form a modulated signal; S3. Obtain the chopping timing of the motor driver; S4. Select a signal transmission period according to the chopping timing sequence; S5. During the signal transmission period, the modulated signal is coupled to the power supply wire of the electric vehicle's power battery.

[0006] The second technical solution adopted in this invention is: A signal transmission device for implementing the above-described signal transmission method includes a motor driver module and a communication module integrated inside the motor driver of an electric vehicle, wherein the communication module and the motor driver module share a power supply. The motor driver module includes a first CPU unit and a power switch driver unit, and the communication module includes a carrier modulation unit and a timing pulse unit. The first CPU unit is connected to the carrier modulation unit and the timing pulse unit respectively; The carrier modulation unit is used to modulate the communication signal onto a carrier wave to form a modulated signal; The timing pulse unit is used to select a signal transmission period according to the chopping timing sequence; The power switch drive unit is connected to the first CPU unit and an external motor, respectively; The carrier modulation unit is connected to the instrument via the positive and negative wires of the power battery.

[0007] The beneficial effects of this invention are as follows: This method generates a communication signal to be sent to the instrument within the motor driver, modulates the communication signal onto a carrier wave to form a modulated signal, obtains the chopping timing of the power switch within the motor driver, selects a signal transmission period based on the chopping timing, and finally couples the modulated signal to the power battery power supply wire of the electric vehicle within this signal transmission period, achieving a complete closed-loop process. This realizes a deep integration of communication function and motor driver working mechanism. Specifically, step S1 directly generates the signal within the motor driver, eliminating the need for an additional signal generation module, simplifying the system structure and reducing hardware redundancy costs; step S2, through signal modulation processing, improves the anti-interference foundation for signal transmission on the power supply wire, laying the groundwork for subsequent stable transmission; step S3, by obtaining the chopping timing of the motor driver, ensures that signal transmission matches the operating rhythm of the motor driver, avoiding conflicts with the power switch operation; step S4, by selecting a signal transmission period based on the chopping timing, achieves timing coordination between signal transmission and motor drive, providing crucial support for avoiding strong interference areas and ensuring transmission stability; step S5... The modulated signal is coupled to the power battery power supply wire, directly reusing the existing power supply line as the communication medium. This eliminates the need for additional CAN or 485 bus laying required in traditional technologies. It not only reduces the material procurement cost of dedicated communication harnesses and the manual assembly cost of vehicle wiring, but also simplifies the wiring layout and reduces the potential for failures caused by additional lines. At the same time, the entire process does not require significant modifications to the existing power supply system and motor drive structure of the electric vehicle, making it highly adaptable. From the process design level, it directly solves the core problem of complex and costly communication wiring in existing technologies, ultimately achieving a stable and low-cost one-way signal transmission between the motor drive and the instrument. Attached Figure Description

[0008] Figure 1 This is a flowchart of the signal transmission method for low-voltage electric vehicles according to the present invention. Figure 2 This is a connection block diagram of the signal transmission device of the present invention; Label Explanation: 1. Motor driver; 11. First CPU unit; 12. Power switch drive unit; 13. Carrier modulation unit; 14. Timing pulse unit; 2. Instruments; 21. Carrier demodulator; 22. Second CPU unit; 23. Display module; 3. Motor. Detailed Implementation

[0009] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0010] Please refer to Figure 1 The first technical solution adopted in this invention is: A signal transmission method for low-voltage electric vehicles includes the following steps: S1. Generate a communication signal to be sent to the instrument 2 inside the motor driver 1 of the electric vehicle; S2. Modulate the communication signal onto a carrier wave to form a modulated signal; S3. Obtain the chopping timing of the motor driver 1; S4. Select a signal transmission period according to the chopping timing sequence; S5. During the signal transmission period, the modulated signal is coupled to the power supply wire of the electric vehicle's power battery.

[0011] As can be seen from the above description, the beneficial effects of the present invention are as follows: This method generates a communication signal to be sent to the instrument 2 within the motor driver 1, modulates the communication signal onto a carrier wave to form a modulated signal, obtains the chopping timing of the power switch within the motor driver 1, selects a signal transmission period based on the chopping timing, and finally couples the modulated signal to the power battery power supply wire of the electric vehicle within this signal transmission period, achieving a complete closed-loop process. This realizes a deep integration of communication function and the working mechanism of the motor driver 1. Specifically, step S1 directly generates the signal within the motor driver 1, eliminating the need for an additional signal generation module, simplifying the system structure and reducing hardware redundancy costs; step S2, through signal modulation processing, improves the anti-interference foundation for signal transmission on the power supply wire, laying the groundwork for subsequent stable transmission; step S3, by obtaining the chopping timing of the motor driver 1, ensures that signal transmission matches the working rhythm of the motor driver 1, avoiding conflicts with the power switch operation; step S4, by selecting a signal transmission period based on the chopping timing, achieves timing coordination between signal transmission and motor drive, providing crucial support for avoiding strong interference areas and ensuring transmission stability; step S5... The modulated signal is coupled to the power battery power supply wire, directly reusing the existing power supply line as the communication medium. This eliminates the need for additional CAN or 485 bus laying in traditional technologies. It not only reduces the material procurement cost of dedicated communication harnesses and the manual assembly cost of vehicle wiring, but also simplifies the wiring layout and reduces the potential for failures caused by additional lines. At the same time, the entire process does not require significant modifications to the existing power supply system of the electric vehicle and the main structure of the motor driver 1. It has strong adaptability and directly solves the core problem of complex and costly communication wiring in existing technologies from the process design level. Ultimately, it reliably realizes stable and low-cost one-way signal transmission between the motor driver 1 and the instrument 2.

[0012] Furthermore, the midpoint of the signal transmission period is located near the midpoint of a chopping cycle defined by the chopping timing.

[0013] As can be seen from the above description, setting the midpoint of the signal transmission period near the midpoint of the chopping cycle avoids the areas with the strongest electromagnetic interference, namely the rising and falling edges of the chopping pulse. The electrical environment near the midpoint of the chopping cycle is relatively stable, with minimal electromagnetic interference, providing a clean transmission environment for communication signals. This effectively reduces the impact of interference on the signal, significantly improves the stability and reliability of communication signal transmission, and ensures the accuracy of low-speed signal transmission.

[0014] Furthermore, the duration of the signal transmission period is 0.2 to 0.3 times the chopping period.

[0015] As can be seen from the above description, the duration of the signal transmission period is limited to 0.2 to 0.3 times the chopping period. This ensures that there is enough time to complete the transmission of the communication signal and meet the needs of low-speed signal transmission, while avoiding the possibility of entering areas with strong interference due to excessively long transmission periods. A good balance is achieved between transmission efficiency and anti-interference capability, further ensuring the stability and effectiveness of communication.

[0016] Furthermore, in step S5, the actual time at which the modulation signal is coupled to the power supply conductor is controlled within a range based on the theoretical midpoint time of the chopping period.

[0017] As can be seen from the above description, the actual time when the modulated signal is coupled to the power supply conductor is based on the theoretical midpoint of the chopping period. By precisely controlling the actual transmission time, it is ensured that the signal transmission is strictly within the period of least interference. This limitation further improves the accuracy and relevance of the signal transmission, avoids electromagnetic interference due to the transmission time deviating from the ideal range, and provides a stronger guarantee for communication reliability.

[0018] Furthermore, the deviation between the actual time and the theoretical midpoint time of the chopping period is within the range of -5μs to 5μs.

[0019] As described above, by limiting the deviation between the actual time and the theoretical midpoint time to -5μs to 5μs, high-precision control of the signal transmission time is achieved. This deviation range can maximize the guarantee that the signal transmission is in the optimal transmission range near the midpoint of the chopping cycle, avoiding electromagnetic interference areas, minimizing the interference experienced by the communication signal during transmission, significantly improving the anti-interference capability and accuracy of signal transmission, and ensuring the reliability of data transmission.

[0020] Furthermore, in step S2, frequency shift keying modulation is used to modulate the communication signal onto the carrier wave.

[0021] As can be seen from the above description, frequency shift keying modulation is used to modulate the communication signal. This modulation method has the advantages of strong anti-interference ability, simple demodulation, and low bit error rate. It can effectively resist various noises and interferences in the electrical system of low-voltage electric vehicles, ensure the stable transmission of the modulated signal on the power battery power supply line, and accurately transmit communication information even in complex electrical environments, thereby improving the reliability and effectiveness of signal transmission.

[0022] Furthermore, the frequency range of the carrier is 100kHz to 1MHz.

[0023] As can be seen from the above description, the carrier in this frequency range has good transmission characteristics, can achieve efficient transmission on the power battery power supply line, and is not easily affected by external low-frequency interference.

[0024] Please refer to Figure 2 The second technical solution adopted in this invention is as follows: A signal transmission device for implementing the above-described signal transmission method includes a motor driver module and a communication module integrated inside the motor driver 1 of an electric vehicle, wherein the communication module and the motor driver module share a power supply. The motor driver module includes a first CPU unit 11 and a power switch driver unit 12, and the communication module includes a carrier modulation unit 13 and a timing pulse unit 14. The first CPU unit 11 is connected to the carrier modulation unit 13 and the timing pulse unit 14 respectively; The carrier modulation unit 13 is used to modulate the communication signal onto a carrier wave to form a modulated signal; The timing pulse unit 14 is used to select a signal transmission period according to the chopping timing sequence; The power switch drive unit 12 is connected to the first CPU unit 11 and the external motor 3, respectively. The carrier modulation unit 13 is connected to the instrument 2 via the positive and negative wires of the power battery.

[0025] As can be seen from the above description, the beneficial effects of the present invention are as follows: This device achieves high system integration by integrating the motor driver module and communication module inside the motor driver 1 and sharing a power supply. This reduces the size of the device and improves the system's compactness and integration. Sharing a power supply not only simplifies the circuit structure but also reduces energy consumption. The carrier modulation unit 13 and the timing pulse unit 14 ensure accurate signal modulation and transmission timing control. The design of the connection between the power switch drive unit 12 and the external motor 3 ensures the coordinated operation of motor drive and signal transmission. The overall device structure is reasonable and easy to install and maintain.

[0026] Furthermore, the motor driver module and the communication module are housed within the same enclosed housing.

[0027] As can be seen from the above description, placing the motor driver module and the communication module in the same sealed housing can, on the one hand, provide good protection for the internal electronic components, preventing damage to the components from external environmental factors such as dust and moisture, and improving the service life and stability of the device; on the other hand, it further enhances the system integration, reduces the connection of external lines, lowers the probability of failure, and also facilitates the overall installation and disassembly of the device, improving the convenience of use.

[0028] Furthermore, the instrument 2 is equipped with a carrier demodulator 21 and a second CPU unit 22. The second CPU unit 22 is connected to the carrier demodulator 21, and the carrier demodulator 21 is connected to the carrier modulation unit 13 through the positive and negative wires of the power battery.

[0029] As described above, a carrier demodulator 21 and a second CPU unit 22 are installed inside the instrument panel 2. The carrier demodulator 21 is used to receive and demodulate the modulated signal from the power battery power supply wire, and the second CPU unit 22 is used to process the demodulated signal. This design realizes a complete signal reception, demodulation and processing process, ensuring that the instrument panel 2 can accurately obtain the communication information sent by the motor driver 1 and perform corresponding processing and display. The carrier demodulator 21 and the carrier modulation unit 13 are connected through the positive and negative wires of the power battery to form a complete communication loop, ensuring the smooth realization of unidirectional signal transmission, so that users can intuitively obtain vehicle-related data through the instrument panel 2, thus improving the user experience.

[0030] Please refer to Figure 1 Embodiment 1 of the present invention is as follows: A signal transmission method for low-voltage electric vehicles includes the following steps: S1. Generate a communication signal to be sent to the instrument 2 inside the motor driver 1 of the electric vehicle; S2. Modulate the communication signal onto a carrier wave to form a modulated signal; the frequency range of the carrier wave is 100kHz~1MHz.

[0031] In step S2, the communication signal is modulated onto the carrier wave using frequency shift keying modulation.

[0032] S3. Obtain the chopping timing of the motor driver 1; S4. Select a signal transmission period according to the chopping timing sequence; The midpoint of the signal transmission period is located near the midpoint of a chopping cycle defined by the chopping timing.

[0033] The duration of the signal transmission period is 0.2 to 0.3 times the chopping period.

[0034] The deviation between the actual time and the theoretical midpoint time of the chopping period is within the range of -5μs to 5μs.

[0035] S5. During the signal transmission period, the modulated signal is coupled to the power supply wire of the electric vehicle's power battery.

[0036] In step S5, the actual time at which the modulation signal is coupled to the power supply conductor is controlled within a range based on the theoretical midpoint time of the chopping period.

[0037] Please refer to Figure 2 Embodiment two of the present invention is as follows: A signal transmission device for implementing the above-described signal transmission method includes a motor driver module and a communication module integrated inside the motor driver 1 of an electric vehicle, wherein the communication module and the motor driver module share a power supply. The motor driver module includes a first CPU unit 11 and a power switch driver unit 12, and the communication module includes a carrier modulation unit 13 and a timing pulse unit 14. The first CPU unit 11 is connected to the carrier modulation unit 13 and the timing pulse unit 14 respectively; The carrier modulation unit 13 is used to modulate the communication signal onto a carrier wave to form a modulated signal; The timing pulse unit 14 is used to select a signal transmission period according to the chopping timing sequence; The power switch drive unit 12 is connected to the first CPU unit 11 and the external motor 3, respectively. The carrier modulation unit 13 is connected to the instrument 2 via the positive and negative wires of the power battery.

[0038] The motor driver module 1 and the communication module are housed in the same enclosed housing.

[0039] The instrument 2 is equipped with a carrier demodulator 21 and a second CPU unit 22. The second CPU unit 22 is connected to the carrier demodulator 21. The carrier demodulator 21 is connected to the carrier modulation unit 13 through the positive and negative wires of the power battery.

[0040] The instrument 2 is also equipped with a display module 23, which is connected to the second CPU unit 22.

[0041] The signal transmission device in this solution mainly consists of two parts: the motor driver (side 1) and the instrument (side 2). Its core working principle revolves around signal generation, modulation, precise transmission, and demodulation, as detailed below: On the motor driver 1 side: the motor driver module and the communication module are integrated in the same sealed housing and share the power supplied by the power battery; the first CPU unit 11 in the motor driver module controls the power switch drive unit 12 to realize the chopper drive of the external motor 3, and generates communication signals (such as motor speed, temperature, fault codes, etc.) to be sent to the instrument 2. The carrier modulation unit 13 in the communication module is connected to the first CPU unit 11. After receiving the communication signal generated by the first CPU unit 11, it uses frequency shift keying modulation (FSK) to modulate the communication signal onto a high-frequency carrier in the frequency range of 100kHz to 1MHz to form a modulated signal.

[0042] Meanwhile, the timing pulse unit 14 in the communication module is connected to the first CPU unit 11 to acquire the chopping timing of the power switch in the motor driver 1 in real time. The timing pulse unit 14 selects a signal transmission period based on the acquired chopping timing. The midpoint of this transmission period is located near the midpoint of each chopping cycle, and the duration is 0.2 to 0.3 times the chopping cycle. The actual time when the modulation signal is coupled to the power battery power supply wire is controlled within a deviation range of -5μs to 5μs based on the theoretical midpoint time of the chopping cycle.

[0043] During the selected signal transmission period, the carrier modulation unit 13 injects the generated modulation signal into the positive and negative power supply wires of the electric vehicle's power battery through a coupling circuit, and uses the power supply wires as a communication medium to realize signal transmission.

[0044] On the instrument 2 side: The instrument 2 is equipped with a carrier demodulator 21 and a second CPU unit 22. The carrier demodulator 21 is connected to the carrier modulation unit 13 on the motor driver 1 side through the positive and negative wires of the power battery, forming a complete one-way communication loop. The carrier demodulator 21 continuously monitors the signal on the power battery power supply wire. When it detects a high-frequency modulation signal from the motor driver 1 side, it demodulates the signal to restore the original communication signal and transmits the communication signal to the second CPU unit 22. After the second CPU unit 22 further processes the communication signal, it controls the display module 23 of the instrument 2 to display relevant information (such as motor speed, temperature, fault codes, etc.) to the user, thereby completing the entire signal transmission process.

[0045] The key to the entire working principle lies in precise timing control and anti-interference design. By strictly limiting the signal transmission period to a low-interference region near the midpoint of the chopping cycle, combined with frequency shift keying modulation and a carrier wave within a specific frequency range, the strong electromagnetic interference generated by the motor-driven chopping action is effectively avoided, ensuring reliable transmission of the modulated signal on the power battery power supply wire. At the same time, by using the existing power supply wire as a communication medium, the goal of saving lines, reducing costs, and simplifying the structure is achieved.

[0046] In summary, the present invention provides a signal transmission method and device for low-voltage electric vehicles. This completes a closed-loop process by generating a communication signal to be sent to an instrument within the motor driver, modulating the communication signal onto a carrier wave to form a modulated signal, acquiring the chopping timing of the power switch within the motor driver, selecting a signal transmission period based on the chopping timing, and finally coupling the modulated signal to the power battery power supply wire of the electric vehicle within that signal transmission period. This achieves deep integration of communication functions and the motor driver's operating mechanism. Specifically, step S1 directly generates the signal within the motor driver, eliminating the need for an additional signal generation module, simplifying the system structure and reducing hardware redundancy costs. Step S2, through signal modulation processing, enhances the anti-interference foundation for signal transmission on the power supply wire, laying the groundwork for subsequent stable transmission. Step S3, by acquiring the chopping timing of the motor driver, ensures that signal transmission matches the operating rhythm of the motor driver, avoiding conflicts with the power switch operation. Step S4, by selecting a signal transmission period based on the chopping timing, achieves timing coordination between signal transmission and motor drive, providing crucial support for avoiding strong interference areas and ensuring transmission stability. Step S5... The modulated signal is coupled to the power battery power supply wire, directly reusing the existing power supply line as the communication medium. This eliminates the need for additional CAN or 485 bus laying required in traditional technologies. It not only reduces the material procurement cost of dedicated communication harnesses and the manual assembly cost of vehicle wiring, but also simplifies the wiring layout and reduces the potential for failures caused by additional lines. At the same time, the entire process does not require significant modifications to the existing power supply system and motor drive structure of the electric vehicle, making it highly adaptable. From the process design level, it directly solves the core problem of complex and costly communication wiring in existing technologies, ultimately achieving a stable and low-cost one-way signal transmission between the motor drive and the instrument.

[0047] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A signal transmission method for low-voltage electric vehicles, characterized in that, Includes the following steps: S1. Generate a communication signal to be sent to the instrument inside the motor driver of the electric vehicle; S2. Modulate the communication signal onto a carrier wave to form a modulated signal; S3. Obtain the chopping timing of the motor driver; S4. Select a signal transmission period according to the chopping timing sequence; S5. During the signal transmission period, the modulated signal is coupled to the power supply wire of the electric vehicle's power battery.

2. The signal transmission method for low-voltage electric vehicles according to claim 1, characterized in that, The midpoint of the signal transmission period is located near the midpoint of a chopping cycle defined by the chopping timing.

3. The signal transmission method for low-voltage electric vehicles according to claim 2, characterized in that, The duration of the signal transmission period is 0.2 to 0.3 times the chopping period.

4. The signal transmission method for low-voltage electric vehicles according to claim 2, characterized in that, In step S5, the actual time at which the modulation signal is coupled to the power supply conductor is controlled within a range based on the theoretical midpoint time of the chopping period.

5. The signal transmission method for low-voltage electric vehicles according to claim 4, characterized in that, The deviation between the actual time and the theoretical midpoint time of the chopping period is within the range of -5μs to 5μs.

6. The signal transmission method for low-voltage electric vehicles according to claim 1, characterized in that, In step S2, the communication signal is modulated onto the carrier wave using frequency shift keying modulation.

7. The signal transmission method for low-voltage electric vehicles according to claim 1, characterized in that, The frequency range of the carrier is 100kHz to 1MHz.

8. A signal transmission apparatus for implementing the signal transmission method for a low-voltage electric vehicle according to any one of claims 1-7, characterized in that, It includes a motor driver module and a communication module integrated inside the motor driver of the electric vehicle, wherein the communication module and the motor driver module share a power supply; The motor driver module includes a first CPU unit and a power switch driver unit, and the communication module includes a carrier modulation unit and a timing pulse unit. The first CPU unit is connected to the carrier modulation unit and the timing pulse unit respectively; The carrier modulation unit is used to modulate the communication signal onto a carrier wave to form a modulated signal; The timing pulse unit is used to select a signal transmission period according to the chopping timing sequence; The power switch drive unit is connected to the first CPU unit and an external motor, respectively; The carrier modulation unit is connected to the instrument via the positive and negative wires of the power battery.

9. The signal transmission device according to claim 8, characterized in that, The motor driver module and the communication module are housed in the same enclosed housing.

10. The signal transmission device according to claim 8, characterized in that, The instrument is equipped with a carrier demodulator and a second CPU unit. The second CPU unit is connected to the carrier demodulator, and the carrier demodulator is connected to the carrier modulation unit through the positive and negative wires of the power battery.

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