PWM current signal acquisition device and PWM current signal acquisition system

Abstract

The utility model relates to a PWM current signal acquisition device and system, the device comprises a signal acquisition circuit and a protection circuit, the signal acquisition circuit comprises a first resistor R1, a second resistor R2 and a comparator U1, and the resistance value of the second resistor R2 is far greater than that of the first resistor R1; the first end of the first resistor R1 inputs a PWM current signal, and the second end of the first resistor R1 is grounded so as to convert the PWM current signal into a PWM voltage signal; the first input end of the comparator U1 is connected in series with the second resistor R2 and then is connected with the first end of the first resistor R1, and is used for collecting PWM voltage signals. The second input end of the comparator U1 is used for inputting a reference voltage, the output end of the comparator U1 is connected with the second input end of the comparator U1, and the output end of the comparator U1 is used for outputting an adjusted square wave signal according to the reference voltage and a PWM voltage signal; and the protection circuit is connected with the first resistor R1 and is used for cutting off the connection between the first resistor R1 and the ground when the input PWM current signal is abnormal. According to the utility model, the reliability and safety of signal acquisition are improved.

Description

Technical Field

[0001] This utility model relates to the field of automotive control technology, specifically to a PWM current signal acquisition device and a PWM current signal acquisition system. Background Technology

[0002] During vehicle operation, to meet the overall vehicle control requirements such as operation, gear shifting, and braking, it is necessary to detect the rotational speeds of components such as the engine, wheel ends, motors, and transmission output shafts. PWM current signal output speed sensors are a widely used type of speed sensor in vehicles. Figure 1 As shown in the installation example, it senses the tooth tips and grooves of the rotating magnetic gear ring in a non-contact manner, outputting different current values ​​to generate PWM current signals to provide feedback on the rotation speed. It also features convenient and simple installation, strong anti-interference capability, and the ability to identify forward and reverse rotation. For example... Figure 2 The image shows a current waveform acquired by a current-type PWM sensor in a specific scenario. Figure 3 This is the parameter table corresponding to the current waveform. (Combined with...) Figure 2 and Figure 3 As shown, if the current signal collected by the current-type PWM sensor is used properly, relatively accurate vehicle operation information can be obtained.

[0003] However, existing automotive electronic PWM signal acquisition and processing circuit designs prioritize the functionality of the acquired signals, neglecting their protection capabilities. If a front-end sensor malfunctions, causing a large current to flow into the signal acquisition device, it could damage components in the back-end circuitry. Therefore, it is necessary to develop a PWM current signal acquisition scheme that balances functionality and safety. Utility Model Content

[0004] Based on the above description, this utility model provides a PWM current signal acquisition device and a PWM current signal acquisition system, which can efficiently complete the acquisition of PWM current signals while ensuring safety, thereby improving the reliability of PWM current signal acquisition.

[0005] The technical solution of this utility model to solve the above-mentioned technical problems is as follows:

[0006] According to a first aspect of the present invention, a PWM current signal acquisition device is provided, comprising a signal acquisition circuit and a protection circuit, wherein:

[0007] The signal acquisition circuit includes a first resistor R1, a second resistor R2, and a comparator U1, wherein the resistance value of the second resistor R2 is much larger than that of the first resistor R1.

[0008] The first end of the first resistor R1 serves as the input terminal for the PWM current signal, and the second end is grounded, which is used to convert the PWM current signal into a PWM voltage signal.

[0009] The comparator U1 has a first input terminal, a second input terminal, and an output terminal. The first input terminal of the comparator U1 is connected in series with the second resistor R2 and then connected to the first terminal of the first resistor R1 for acquiring the PWM voltage signal. The second input terminal of the comparator U1 is used to input a reference voltage. The output terminal of the comparator U1 is connected to the second input terminal of the comparator U1 and is used to output an adjusted square wave signal according to the reference voltage and the PWM voltage signal.

[0010] The protection circuit is connected to the first resistor R1 and is used to disconnect the first resistor R1 from ground when the input PWM current signal is abnormal.

[0011] Based on the above technical solution, the present invention can be further improved as follows.

[0012] Furthermore, the signal acquisition circuit also includes a third resistor R3, one end of which is connected to the common node of the second resistor R2 and the first input terminal of the comparator U1, and the other end of the third resistor R3 is grounded.

[0013] Furthermore, the protection circuit includes a first switch Q1, a second switch Q2, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6. The first switch Q1 is connected in series between the first resistor R1 and ground. The control terminal of the first switch Q1 is connected to the positive terminal of a DC source after being connected in series with the resistor R4. The common node of the control terminal of the first switch Q1 and the resistor R4 is connected in series with the second switch Q2 and then grounded. The control terminal of the second switch Q2 is connected in series with the resistor R6 and then grounded. The control terminal of the second switch Q2 is also connected in series with the fifth resistor R5 and then to the common node of the first resistor R1 and the second resistor R2.

[0014] Furthermore, the signal acquisition circuit also includes an eighth resistor R8, which is connected in series between the output terminal and the second input terminal of the comparator U1.

[0015] Furthermore, the signal acquisition circuit also includes a seventh resistor R7, and the output terminal of the comparator U1 is connected in series with the seventh resistor R7 and then connected to the positive terminal of the DC source.

[0016] Furthermore, the signal acquisition circuit also includes a reference voltage conditioning circuit, which includes a ninth resistor R9, a tenth resistor R10, a fourth capacitor C4, and a fifth capacitor C5. One end of the ninth resistor R9 is connected to the positive terminal of the DC source, and the other end is connected to the second input terminal of the comparator U1. One end of the tenth resistor R10 is grounded, and the other end is connected to the common node of the ninth resistor R9 and the comparator U1. One end of the fourth capacitor C4 is connected to the positive terminal of the DC source, and the other end is grounded. The fifth capacitor C5 is connected to the common node of the ninth resistor R9 and the comparator U1, and the other end is grounded.

[0017] Furthermore, the signal acquisition circuit also includes a first capacitor C1, one end of which is connected to the first end of the first resistor R1, and the other end is grounded.

[0018] Furthermore, the signal acquisition circuit also includes a second capacitor C2, one end of which is connected to the first input terminal of the comparator U1 and the other end is grounded.

[0019] Furthermore, the signal acquisition circuit also includes a third capacitor C3, one end of which is connected to the output terminal of the comparator U1 and the other end is grounded.

[0020] According to a second aspect of the present invention, a PWM current signal acquisition system is also provided, including a current-type PWM sensor and the aforementioned PWM current signal acquisition device, wherein the current-type PWM sensor is used to detect the PWM current signal that feeds back vehicle speed information and transmit it to the PWM current signal acquisition device.

[0021] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: The PWM current signal acquisition device and PWM current signal acquisition system provided by this utility model form a PWM current signal acquisition path through grounding the first resistor R1. The PWM current signal is converted into a voltage signal through the first resistor R1, which is acquired by the comparator U1. Then, after being compared with the reference voltage, an adjusted square wave signal is output for the subsequent control unit to analyze vehicle speed information. When the amplitude of the PWM current signal acquired by the sensor is too large under abnormal conditions, the protection circuit disconnects the path between the first resistor R1 and ground in time, protecting the first resistor R1 in the signal acquisition circuit, improving the reliability of PWM current signal acquisition, and enhancing the safety and service life of the device. Attached Figure Description

[0022] Figure 1 Schematic diagram of the mounting structure for a current-type PWM sensor;

[0023] Figure 2The current waveforms detected by the sensor under various operating conditions are provided for a certain embodiment.

[0024] Figure 3 To and Figure 2 Table of detection parameters corresponding to current waveforms;

[0025] Figure 4 This is a schematic diagram illustrating an application scenario of the signal acquisition device provided by this utility model.

[0026] Figure 5 This is a schematic diagram of the circuit principle of the signal acquisition device provided in an embodiment of the present utility model. Detailed Implementation

[0027] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be more thorough and complete.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0029] It is understood that spatial relation terms such as "below," "under," "below," "below," "above," "over," etc., can be used here to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as "below" or "under" or "below" of other elements or features will be oriented "over" of other elements or features. Therefore, the exemplary terms "below" and "under" can include both upper and lower orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0030] It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediary element. In the following embodiments, "connection" should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have the transmission of electrical signals or data between them.

[0031] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0032] Figure 1 This demonstrates a typical detection scenario for a current-type PWM sensor used in a vehicle. Figure 2 and Figure 3 This demonstrates the signal parameters of the current-type PWM sensor used in the vehicle in this scenario, including, for example... Figure 2 The image shows the current waveform obtained by the current-type PWM sensor during the acquisition of vehicle speed information in this scenario. Figure 3 This is the parameter table corresponding to the current waveform. Figure 2 and Figure 3 It can be seen that in this scenario, the typical peak value IHigh of the PWM current waveform is 14mA, and the typical valley value ILow is 7mA. The current signal is transmitted to the signal acquisition circuit in the form of a PWM waveform, and the waveform period changes with the rotational speed of the object being measured. The width of the current pulse changes with the direction and value of the rotational speed. Therefore, it can be concluded that if the current signal acquired by the current-type PWM sensor is used reasonably, relatively accurate vehicle operation information can be obtained.

[0033] Based on the above analysis, please refer to Figure 4 This embodiment provides a PWM current signal acquisition device, which acquires the PWM current signal emitted by a current-type PWM sensor, processes it, and generates a square wave voltage signal that can be recognized by the control unit. The automotive electronic control unit recognizes this square wave voltage signal, converts it into a real-time speed value through software acquisition and calculation, and identifies the current speed direction. During the operation of this device, a power supply circuit provides operating power to the signal acquisition device and the control unit.

[0034] Combination Figure 4 and Figure 5 As shown, the PWM current signal acquisition device provided in this embodiment includes a signal acquisition circuit and a protection circuit, wherein:

[0035] The signal acquisition circuit includes a first resistor R1, a second resistor R2, and a comparator U1, wherein the resistance value of the second resistor R2 is much larger than that of the first resistor R1.

[0036] The first end of the first resistor R1 serves as the input terminal of the PWM current signal, and the second end is grounded to GND, which is used to convert the PWM current signal into a PWM voltage signal.

[0037] The comparator U1 has a first input terminal (e.g., an inverting input terminal), a second input terminal (e.g., a non-inverting input terminal), and an output terminal. The first input terminal of the comparator U1 is connected in series with the second resistor R2 and then connected to the first terminal of the first resistor R1, for acquiring the PWM voltage signal. The second input terminal of the comparator U1 is used to input a reference voltage. The output terminal of the comparator U1 is connected to the second input terminal of the comparator U1, and the output terminal of the comparator U1 is used to output an adjusted square wave signal according to the reference voltage and the PWM voltage signal.

[0038] The protection circuit is connected to the first resistor R1 and is used to disconnect the first resistor R1 from ground GND when the input PWM current signal is abnormal.

[0039] It is understandable that, such as Figure 5 As shown, I_F_SpdA / J is the PWM current signal input, provided by an external current-type PWM sensor; I_F_MSpdA / M is the output signal of the PWM signal acquisition circuit, output from the output of comparator U1 to the main control unit circuit. I_F_MSpdA / J is the PWM voltage signal obtained through the current-to-voltage conversion of the first resistor R1.

[0040] A PWM current signal acquisition path is formed by grounding the first resistor R1. The PWM current signal I_F_SpdA / J provided by the external sensor flows to ground GND through the first resistor R1. The first resistor R1 converts the PWM current signal I_F_SpdA / J into a PWM voltage signal I_F_MSpdA / J, which is acquired by the comparator U1. After being compared with the reference voltage, the adjusted square wave signal is output for the subsequent control unit to analyze the vehicle speed information.

[0041] Because the second resistor R2 is a resistor with a large resistance value, and the resistance value of the second resistor R2 is much larger than the resistance value of the first resistor R1, for example... Figure 5As shown, R1 = 100Ω and R2 = 41.2kΩ. Therefore, under normal operating conditions or when the sensor is short-circuited, the PWM current signal I_F_SpdA / J provided by the external sensor mainly flows to ground GND through the first resistor R1. During normal operation, the second resistor R2 steps down the acquired voltage signal and transmits it to the inverting input of comparator U1. Simultaneously, due to the large resistance of the second resistor R2, it also limits the current to the inverting input of comparator U1, preventing large current from flowing into it. When the sensor is short-circuited (e.g., shorted to a +28V power supply), and the amplitude of the PWM current signal flowing into the device is too large, due to the current-limiting effect of the second resistor R2, the large current flowing into the signal acquisition device mainly flows to ground GND through the first resistor R1 and will not flow into the inverting input of comparator U1. The protection circuit promptly disconnects the connection between the first resistor R1 and ground GND, protecting the first resistor R1 in the signal acquisition circuit, thus providing overcurrent protection for the device. This protection circuit improves the reliability of PWM current signal acquisition, thereby enhancing the safety and lifespan of the device.

[0042] In one possible implementation, such as Figure 5 As shown, the signal acquisition circuit also includes a third resistor R3. One end of the third resistor R3 is connected to the common node of the second resistor R2 and the first input terminal of the comparator U1, and the other end of the third resistor R3 is grounded to GND.

[0043] Understandably, both the second resistor R2 and the third resistor R3 are high-value resistors, and they are connected in series and then grounded. The combined resistance of the second resistor R2 and the third resistor R3 is much greater than the resistance of the first resistor R1, for example... Figure 5 As shown, R1=100Ω, R2=41.2kΩ, and R3=6.04kΩ. Therefore, under normal operating conditions or when the sensor is short-circuited, the PWM current signal I_F_SpdA / J provided by the external sensor mainly flows to ground (GND) through the first resistor R1. When the device is working, the second resistor R2 and the third resistor R3 divide the acquired voltage signal and transmit it to the inverting input of comparator U1. Simultaneously, because the second resistor R2 has a larger resistance, it also limits the current to the inverting input of comparator U1, preventing a large current from flowing into the inverting input of comparator U1.

[0044] In one possible implementation, such as Figure 5As shown, the protection circuit includes a first switching transistor Q1 (taking a transistor as an example), a second switching transistor Q2 (taking a transistor as an example), a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6. The first switching transistor Q1 is connected in series between the first resistor R1 and ground GND. The control terminal of the first switching transistor Q1 is connected to the positive terminal of the DC source after being connected in series with the resistor R4. The common node of the control terminal of the first switching transistor Q1 and the resistor R4 is connected in series with the second switching transistor Q2 and then grounded to GND. The control terminal of the second switching transistor Q2 is connected in series with the resistor R6 and then grounded to GND. The control terminal of the second switching transistor Q2 is also connected in series with the fifth resistor R5 and then connected to the common node of the first resistor R1 and the second resistor R2.

[0045] Understandably, when the device is working normally, the first switch Q1 is in the on state. Due to the large resistance values ​​of the second resistor R2 and the third resistor R3, their voltage division effect is small, while their current limiting effect is large. The PWM current signal I_F_SpdA / J input from the sensor is mainly connected to ground GND through the first resistor R1 and the first switch Q1. A PWM voltage signal I_F_MSpdA / J is generated at the first end of the first resistor R1. This voltage is divided by R2 and R3 and then input to the inverting input of comparator U1.

[0046] In this state, when the input current value of the PWM current signal I_F_SpdA / J is IHigh, the voltage at the non-inverting input terminal of comparator U1 is less than the voltage at the inverting input terminal of comparator U1, and the square wave signal I_F_MSpdA / M output by comparator U1 is at a low potential; when the input current value of the PWM current signal I_F_SpdA / J is ILow, the voltage at the non-inverting input terminal of comparator U1 is greater than the voltage at the inverting input terminal of comparator U1, and the square wave signal I_F_MSpdA / M output by comparator U1 is at a high potential.

[0047] The signal acquisition circuit of this device converts the current-type PWM signal I_F_SpdA / J input from the sensor into a square wave signal I_F_MSpdA / M that the control unit can recognize. The main controller of the control unit can identify the speed and direction of rotation of the measured object by calculating the frequency and low-level pulse width of the square wave signal I_F_MSpdA / M.

[0048] When the sensor output is short-circuited to the power supply, the PWM current signal I_F_SpdA / J of the input device increases abnormally. At this time, the base voltage of the second switch Q2 (taking a transistor as an example) increases, and the second switch Q2 is turned on. The base voltage of the first switch Q1 is pulled down, causing the first switch Q1 to turn off, thereby cutting off the current path and playing a protective role. The inverting input of comparator U1 is effectively protected by voltage division and current limiting through R2 and R3.

[0049] In one possible implementation, such as Figure 5 As shown, the signal acquisition circuit further includes a reference voltage conditioning circuit, which includes a ninth resistor R9, a tenth resistor R10, a fourth capacitor C4, and a fifth capacitor C5. One end of the ninth resistor R9 is connected to the positive terminal of a DC source (e.g., +5V voltage), and the other end is connected to the second input terminal (non-inverting input terminal) of the comparator U1. One end of the tenth resistor R10 is grounded, and the other end is connected to the common node of the ninth resistor R9 and the comparator U1. One end of the fourth capacitor C4 is connected to the positive terminal of the DC source, and the other end is grounded. The fifth capacitor C5 is connected to the common node of the ninth resistor R9 and the comparator U1, and the other end is grounded.

[0050] Understandably, in this embodiment, the +5V voltage generated by the power supply circuit is divided by R9 and R10 and then used as a reference voltage input to the non-inverting input of comparator U1. The fourth capacitor C4 filters the +5V voltage output from the positive terminal of the DC source, and the fifth capacitor C5 filters the reference voltage input to the non-inverting input of comparator U1, making the reference voltage signal input to the non-inverting input of comparator U1 more stable.

[0051] In one possible implementation, such as Figure 5 As shown, the signal acquisition circuit also includes an eighth resistor R8, which is connected in series between the output terminal and the second input terminal of the comparator U1. The eighth resistor R8 constitutes the hysteresis voltage circuit of the comparator U1, which can prevent circuit oscillation, improve the output stability of the circuit and reduce nonlinear distortion, as well as control the output impedance and output power, making the square wave signal I_F_MSpdA / M output by the comparator U1 more stable.

[0052] In one possible implementation, such as Figure 5 As shown, the signal acquisition circuit also includes a seventh resistor R7, and the output terminal of the comparator U1 is connected in series with the seventh resistor R7 and then connected to the positive terminal of the DC source +5V.

[0053] Understandably, the seventh resistor R7 acts as a pull-up resistor, clamping the uncertain signal at the output of comparator U1 to a high level, which is beneficial for the subsequent control unit to accurately identify it; the seventh resistor R7 also serves as a current limiter.

[0054] In one possible implementation, such as Figure 5 As shown, the signal acquisition circuit also includes a first capacitor C1, one end of which is connected to the first terminal of the first resistor R1, and the other end is grounded. The first capacitor C1 filters the PWM current signal I_F_SpdA / J of the input device to make it more stable.

[0055] In one possible implementation, such as Figure 5 As shown, the signal acquisition circuit also includes a second capacitor C2, one end of which is connected to the first input terminal of the comparator U1, and the other end is grounded. The second capacitor C2 filters the voltage signal at the inverting input terminal of the input comparator U1, making the detection signal of the input comparator U1 more stable.

[0056] In one possible implementation, such as Figure 5 As shown, the signal acquisition circuit also includes a third capacitor C3, one end of which is connected to the output of the comparator U1, and the other end is grounded. The third capacitor C3 filters the square wave signal I_F_MSpdA / M output by the comparator U1, making it more stable and facilitating subsequent identification and analysis by the control unit.

[0057] like Figure 4 As shown, based on the aforementioned signal acquisition device embodiments, this utility model embodiment also provides a PWM current signal acquisition system. The system includes a current-type PWM sensor and the PWM current signal acquisition device provided in the aforementioned embodiments. The current-type PWM sensor is used to detect the PWM current signal that feeds back vehicle speed information and transmits it to the PWM current signal acquisition device.

[0058] The PWM current signal acquisition device and system provided by this utility model can effectively realize overcurrent protection during the signal acquisition process, improve the reliability and safety of signal acquisition, and extend the service life of the device. The resistors, capacitors, transistors, and comparators used are all conventional electronic components, the circuit structure is simple, the cost is low, and the practicality is strong, making it suitable for engineering application needs. For current-type PWM signals with different parameters, adaptation can be completed simply by adjusting the resistance value of a resistor, making it highly versatile.

[0059] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A PWM current signal acquisition device, characterized in that, Includes signal acquisition circuits and protection circuits, wherein: The signal acquisition circuit includes a first resistor R1, a second resistor R2, and a comparator U1, wherein the resistance value of the second resistor R2 is much larger than that of the first resistor R1. The first end of the first resistor R1 serves as the input terminal for the PWM current signal, and the second end is grounded, which is used to convert the PWM current signal into a PWM voltage signal. The comparator U1 has a first input terminal, a second input terminal, and an output terminal. The first input terminal of the comparator U1 is connected in series with the second resistor R2 and then connected to the first terminal of the first resistor R1 for acquiring the PWM voltage signal. The second input terminal of the comparator U1 is used to input a reference voltage. The output terminal of the comparator U1 is connected to the second input terminal of the comparator U1 and is used to output an adjusted square wave signal according to the reference voltage and the PWM voltage signal. The protection circuit is connected to the first resistor R1 and is used to disconnect the first resistor R1 from ground when the input PWM current signal is abnormal.

2. The PWM current signal acquisition device according to claim 1, characterized in that, It also includes a third resistor R3, one end of which is connected to the common node of the second resistor R2 and the first input terminal of the comparator U1, and the other end of the third resistor R3 is grounded.

3. The PWM current signal acquisition device according to claim 2, characterized in that, The protection circuit includes a first switch Q1, a second switch Q2, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6. The first switch Q1 is connected in series between the first resistor R1 and ground. The control terminal of the first switch Q1 is connected in series with the resistor R4 and then connected to the positive terminal of the DC source. The common node of the control terminal of the first switch Q1 and the resistor R4 is connected in series with the second switch Q2 and then grounded. The control terminal of the second switch Q2 is connected in series with the resistor R6 and then grounded. The control terminal of the second switch Q2 is also connected in series with the fifth resistor R5 and then connected to the common node of the first resistor R1 and the second resistor R2.

4. A PWM current signal acquisition device according to any one of claims 1 to 3, characterized in that, The signal acquisition circuit also includes an eighth resistor R8, which is connected in series between the output terminal and the second input terminal of the comparator U1.

5. The PWM current signal acquisition device according to claim 4, characterized in that, The signal acquisition circuit also includes a seventh resistor R7, and the output terminal of the comparator U1 is connected in series with the seventh resistor R7 and then connected to the positive terminal of the DC source.

6. The PWM current signal acquisition device according to claim 1, characterized in that, The signal acquisition circuit further includes a reference voltage conditioning circuit, which includes a ninth resistor R9, a tenth resistor R10, a fourth capacitor C4, and a fifth capacitor C5. One end of the ninth resistor R9 is connected to the positive terminal of the DC source, and the other end is connected to the second input terminal of the comparator U1. One end of the tenth resistor R10 is grounded, and the other end is connected to the common node of the ninth resistor R9 and the comparator U1. One end of the fourth capacitor C4 is connected to the positive terminal of the DC source, and the other end is grounded. The fifth capacitor C5 is connected to the common node of the ninth resistor R9 and the comparator U1, and the other end is grounded.

7. The PWM current signal acquisition device according to claim 1, characterized in that, The signal acquisition circuit also includes a first capacitor C1, one end of which is connected to the first end of the first resistor R1 and the other end is grounded.

8. A PWM current signal acquisition device according to claim 1, characterized in that, The signal acquisition circuit also includes a second capacitor C2, one end of which is connected to the first input terminal of the comparator U1 and the other end is grounded.

9. A PWM current signal acquisition device according to claim 1, characterized in that, The signal acquisition circuit also includes a third capacitor C3, one end of which is connected to the output of the comparator U1 and the other end is grounded.

10. A PWM current signal acquisition system, characterized in that, It includes a current-type PWM sensor and a PWM current signal acquisition device as described in any one of claims 1 to 9, wherein the current-type PWM sensor is used to detect the PWM current signal that feeds back vehicle speed information and transmit it to the PWM current signal acquisition device.

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