Locomotive traction control motor speed detection processing circuit

Abstract

The invention provides a locomotive traction control motor speed detection processing circuit. The locomotive traction control motor speed detection processing circuit comprises a filter amplification circuit, a hysteresis comparison isolation circuit and a bus buffer circuit, the filtering and amplifying circuit comprises a voltage adjusting resistor, a filtering capacitor, a filtering resistor, an amplitude limiting diode and an operational amplifier; the hysteresis comparison isolation circuit comprises a voltage regulation circuit, a hysteresis comparator and an isolation optocoupler; the bus buffer circuit is used for controlling cross transmission of each path of data on a bus; the bus buffer circuit includes a plurality of buffers. According to the invention, the voltage regulating resistor is matched with the voltage follower and the hysteresis comparator, so that the speed signal of the traction motor can be effectively detected and processed, and the conversion of the A / D signal is further completed by using the optocoupler isolation circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of detection and processing circuits, and in particular to a speed detection and processing circuit for a locomotive traction control motor. Background Art

[0002] The locomotive traction control unit is called the heart of the electric locomotive and plays a major role in controlling the traction function of the locomotive. Real-time detection and adjustment of the locomotive traction motor speed is an important part of traction control. The speed detection of the locomotive traction motor is usually completed by a speed sensor in conjunction with a speed detection and processing circuit. During the detection process, the sensor will generate an AC signal proportional to the speed of the locomotive traction motor and send it to the traction control unit for speed signal detection, processing and analysis. However, in actual applications, it may be affected by various factors such as line conditions, vibration, electromagnetic interference, and sensor installation, resulting in certain high-frequency noise in the signal. These noises may cause errors in the speed data detected by the control device, affecting the control and operation of the locomotive.

[0003] When the speed sensor detects the rotating magnetic field of the motor, it outputs a series of pulse signals. These pulse signals are processed by the locomotive traction speed data acquisition circuit and sent to the traction control unit CPU. Next, the CPU's timer and counter start timing and count at the rising edge of the pulse signal in each cycle. Finally, the microprocessor calculates the speed of the motor based on the count value of the counter and the preset time constant, and compares it with the target speed of the control unit. If necessary, the control unit will adjust the motor through the output driver to achieve the target speed.

[0004] The current locomotive traction speed data acquisition circuit mainly uses comparison circuits and isolation circuits to filter and calibrate the voltage signal transmitted by the speed sensor, converting it into a suitable pulse signal and sending it to the core processor. Due to the harsh locomotive operating environment, the speed signal collected by the current circuit is easily mixed with interference signals, affecting the accuracy of data acquisition, causing the core CPU to make wrong judgments, thereby affecting the overall operation stability of the electric locomotive. Summary of the invention

[0005] According to the technical problems mentioned in the above background technology, a locomotive traction control motor speed detection processing circuit is provided. The present invention mainly uses a hysteresis comparison circuit as the core part of the speed signal sampling processing, and cooperates with a signal filtering circuit and a bus processing circuit to improve the conversion accuracy and stability of the motor speed sampling processing.

[0006] The technical means adopted by the present invention are as follows:

[0007] A locomotive traction control motor speed detection and processing circuit comprises: a filter amplifier circuit, a hysteresis comparison isolation circuit and a bus buffer circuit;

[0008] The filter amplifier circuit includes: a voltage adjustment resistor, a filter capacitor, a filter resistor, a limiting diode and an operational amplifier; the motor speed sensor sends a pulse voltage signal to the voltage adjustment resistor, which is divided by the voltage adjustment resistor and filtered by an RC filter circuit composed of the filter resistor and the filter capacitor, and then passes through the limiting diode to ensure that the voltage range is limited to a certain range, and the determined voltage is sent to the operational amplifier to adjust the voltage amplitude;

[0009] The hysteresis comparison isolation circuit comprises: a voltage adjustment circuit, a hysteresis comparator and an isolation optical coupler;

[0010] The bus buffer circuit is used to control the cross transmission of each data on the bus; the bus buffer circuit includes a plurality of buffers.

[0011] Furthermore, in the hysteresis comparison isolation circuit, the voltage adjustment resistors R1 and R2 cooperate with the operational amplifier II to adjust the power supply voltage VCC to the reference voltage VREF.

[0012] Furthermore, the hysteresis comparator inputs the reference voltage through a voltage follower; the voltage follower disconnects the power supply circuit through high impedance, and the low output impedance of the voltage follower enables the subsequent circuit to directly read the output voltage of the voltage follower.

[0013] Furthermore, the working principle of the hysteresis comparator is:

[0014] In the forward process, when the comparator input voltage U IN Greater than the hysteresis interval high voltage threshold U T2 When the comparator output changes from high level U1 to low level U2; in the reverse process, when the comparator input voltage U IN Less than the hysteresis interval low voltage threshold U T1 When , the comparator output changes from low level U2 to high level U1; according to the virtual short and virtual break characteristics of the amplifier, the output type of the hysteresis comparator is an open collector output, then the forward voltage U1 is the comparator forward supply voltage VCC, and the reverse voltage U2 is the reference ground, that is, 0V, then the calculation formula of the hysteresis comparator threshold voltage is:

[0015]

[0016] The calculations show that:

[0017]

[0018] Hysteresis low voltage threshold

[0019]

[0020] The voltage of the hysteresis comparator circuit is adjusted by changing the resistance values ​​of R1, R2, R3, and R4.

[0021] Furthermore, pin 1 of the buffer is connected to the control signal pin of the CPU through a pull-up resistor. When the control signal is at a low level, the output end transmits normally, and when the control signal is at a high level, the output end is in a high-impedance state.

[0022] Furthermore, the buffer is of TC74VHC541 type.

[0023] Furthermore, the output end of the comparator is connected to the cathode of the diode at the input end of the isolation optocoupler device. When the comparator outputs an open collector signal, the optocoupler is not turned on. When the comparator output is ground, the optocoupler is turned on. The voltage at both ends of the optocoupler and the ground need to be isolated from each other.

[0024] Furthermore, the input and output of the optical coupler are isolated from each other, and the electrical signal transmission is unidirectional.

[0025] Furthermore, an inverter is provided at the rear end of the optical coupler to perform reverse logic processing on the signal.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The present invention uses a voltage regulating resistor in conjunction with a voltage follower and a hysteresis comparator to effectively detect and process the traction motor speed signal, and uses an optocoupler isolation circuit to further complete the A / D signal conversion. Speed ​​sensors of different specifications and models can also be adapted by changing the VCC value of the detection circuit according to the different amplitudes of the speed signal, so that the CPU can accurately calculate and reliably control the motor speed, thereby improving the reliability and stability of the locomotive traction control. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 This is the overall circuit structure scheme of the present invention.

[0030] Figure 2 This is a circuit diagram of the filter amplifier circuit of the present invention.

[0031] Figure 3 This is a circuit diagram of the hysteresis comparison isolation circuit of the present invention.

[0032] Figure 4 It is a diagram illustrating the working principle of the hysteresis comparator of the present invention.

[0033] Figure 5 (a) is a schematic diagram of the bus buffer circuit of the present invention.

[0034] Figure 5 (b) is the internal schematic diagram of TC74VHC541. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0037] like Figure 1-5 As shown, the present invention provides a locomotive traction control motor speed detection and processing circuit, including: a filter amplifier circuit, a hysteresis comparison isolation circuit and a bus buffer circuit.

[0038] In this application, if Figure 2As shown in the figure, the filtering and amplifying circuit includes: a voltage regulating resistor, a filtering capacitor, a filtering resistor, a clamping diode, and an operational amplifier; the motor speed measuring sensor sends a pulse voltage signal to the voltage regulating resistor, which is divided by the voltage regulating resistor and then filtered by the RC filtering circuit composed of the filtering resistor and the filtering capacitor, and then passes through the clamping diode to ensure that the voltage range is limited within a certain range (0 to VCC), and the determined voltage is sent to the operational amplifier for voltage amplitude adjustment. As a preferred embodiment, the circuit adds a self-checking function. At the initial startup stage of the circuit, the CPU processor sends a TEST signal to the front end of the circuit, and ensures that the circuit components are not damaged through the detection result. Otherwise, it will prompt a circuit fault, and the traction control unit CPU will turn off the control function. After the fault is removed and the self-checking passes again, the normal function will be restored.

[0039] In a preferred embodiment, in the present application, the hysteresis comparator isolation circuit includes: a voltage adjustment circuit, a hysteresis comparator, and an isolation optocoupler. The voltage regulating resistors R1 and R2 cooperate with the operational amplifier 2 to adjust the power supply voltage VCC to VREF that meets the circuit requirements. Here, a voltage follower is used to send the reference voltage to the hysteresis comparator. The voltage follower disconnects the power supply circuit through a high impedance, which is equivalent to being open-circuited with the previous-stage circuit; at the same time, its low output impedance enables the subsequent-stage circuit to directly read the output voltage of the voltage follower, thus playing an isolation role. This isolation effect can protect the subsequent-stage circuit, reduce interference and the influence of back electromotive force, and improve the stability of the circuit. A simple comparator outputs a high level when VIN(+) > VIN(-); it outputs a low level when VIN(+) < VIN(-). However, when the signals at the two input terminals are relatively close, due to the input voltage spikes, the output will generate continuous jumps. The hysteresis comparator can well solve this problem and has strong anti-interference ability.

[0040] The working principle of the hysteresis comparator is as Figure 4 shown. In the forward process, when U IN is greater than U T2 , the comparator output changes from U1 to U2. In the reverse process, when U IN is less than U T1 , the comparator output changes from U2 to U1.

[0041] According to the virtual short and virtual open characteristics of the amplifier, the calculation formula for the threshold voltage of the hysteresis comparator in Figure 3 can be derived.

[0042] In Figure 3 the circuit, the comparator output type is open-collector output, then the forward voltage U1 is the comparator forward supply voltage VCC, and the reverse voltage U2 is the reference ground, which is 0V.

[0043] In the voltage adjustment circuit,

[0044] It can be calculated

[0045]

[0046] The voltage of the hysteresis comparator circuit can be flexibly adjusted by changing the resistance values ​​of R1, R2, R3, and R4 to adapt to motor speed signals of different amplitudes and effectively filter out clutter interference within the effective amplitude range of the speed signal to achieve a suitable motor speed signal processing effect.

[0047] The output of the comparator is connected to the cathode of the diode at the input of the third part of the isolation optocoupler. When the comparator output is an open collector signal, the optocoupler is not conducting. When the comparator output is ground, the optocoupler is conducting. The voltage and ground at both ends of the optocoupler need to be isolated from each other. The input and output of the optocoupler are isolated from each other, and the transmission of electrical signals is unidirectional, which effectively enhances the electrical insulation and anti-interference ability of the circuit. An inverter is added at the back end of the optocoupler to perform reverse logic processing on the signal. After passing through the second part, the signal is converted from analog signal to digital signal.

[0048] The present invention also includes a bus transceiver buffer circuit, such as Figure 5 As shown, the buffer uses the TC74VHC541 model, and other models with similar functions can also be used instead. Pin 1 of the chip is connected to the control signal pin of the CPU through a pull-up resistor. When the control signal is at a low level, the output end transmits normally. When the control signal is at a high level, the output end is in a high-impedance state. The bus transceiver buffer circuit is mainly used to control the cross transmission of each data on the bus to avoid data conflicts. When several data channels are to be transmitted to the bus, the buffer of each channel is used to solve the problem. When one channel is transmitted, the buffer disconnects the other data channels from the bus. When the data receiving port of the CPU processor is multiplexed, the buffer can play an important role.

[0049] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0050] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts not described in detail in a certain embodiment, reference can be made to the relevant description of other embodiments. In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A locomotive traction control motor speed detection and processing circuit, characterized in that: include: Filter amplifier circuit, hysteresis comparison isolation circuit and bus buffer circuit; The filter amplifier circuit includes: a voltage adjustment resistor, a filter capacitor, a filter resistor, a limiting diode and an operational amplifier; the motor speed sensor sends a pulse voltage signal to the voltage adjustment resistor, which is divided by the voltage adjustment resistor and filtered by an RC filter circuit composed of the filter resistor and the filter capacitor, and then passes through the limiting diode to ensure that the voltage range is limited to a certain range, and the determined voltage is sent to the operational amplifier to adjust the voltage amplitude; The hysteresis comparison isolation circuit comprises: a voltage adjustment circuit, a hysteresis comparator and an isolation optical coupler; The bus buffer circuit is used to control the cross transmission of each data on the bus; the bus buffer circuit includes a plurality of buffers.

2. A locomotive traction control motor speed detection and processing circuit according to claim 1, characterized in that: In the hysteresis comparison isolation circuit, the voltage adjustment resistors R1 and R2 cooperate with the operational amplifier II to adjust the power supply voltage VCC to the reference voltage VREF.

3. A locomotive traction control motor speed detection and processing circuit according to claim 1, characterized in that: The hysteresis comparator inputs the reference voltage through a voltage follower; the voltage follower disconnects the power supply circuit through high impedance, and the low output impedance of the voltage follower enables the subsequent circuit to directly read the output voltage of the voltage follower.

4. A locomotive traction control motor speed detection and processing circuit according to claim 1, characterized in that: The working principle of the hysteresis comparator is: In the forward process, when the comparator input voltage U IN Greater than the hysteresis interval high voltage threshold U T2 When the comparator output changes from high level U1 to low level U2; in the reverse process, when the comparator input voltage U IN Less than the hysteresis interval low voltage threshold U T1 When , the comparator output changes from low level U2 to high level U1; according to the virtual short and virtual break characteristics of the amplifier, the output type of the hysteresis comparator is an open collector output, then the forward voltage U1 is the comparator forward supply voltage VCC, and the reverse voltage U2 is the reference ground, that is, 0V, then the calculation formula of the hysteresis comparator threshold voltage is: The calculations show that: Hysteresis high voltage threshold Hysteresis low voltage threshold The voltage of the hysteresis comparator circuit is adjusted by changing the resistance values ​​of R1, R2, R3, and R4.

5. The locomotive traction control motor speed detection and processing circuit according to claim 1, characterized in that: Pin 1 of the buffer is connected to the control signal pin of the CPU through a pull-up resistor. When the control signal is at a low level, the output end transmits normally, and when the control signal is at a high level, the output end is in a high-impedance state.

6. A locomotive traction control motor speed detection and processing circuit according to claim 1, characterized in that: The buffer is of type TC74VHC541.

7. A locomotive traction control motor speed detection and processing circuit according to claim 1, characterized in that: The output end of the comparator is connected to the cathode of the diode at the input end of the isolation optocoupler device. When the comparator outputs an open collector signal, the optocoupler is not turned on. When the comparator output is ground, the optocoupler is turned on. The voltage at both ends of the optocoupler and the ground need to be isolated from each other.

8. A locomotive traction control motor speed detection and processing circuit according to claim 1, characterized in that: The input and output of the optical coupler are isolated from each other, and the electrical signal transmission is unidirectional.

9. A locomotive traction control motor speed detection and processing circuit according to claim 1, characterized in that: An inverter is arranged at the rear end of the optical coupler to perform reverse logic processing on the signal.

10. A locomotive traction control motor speed detection and processing circuit according to claim 1, characterized in that: The certain range is 0 to VCC.

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