Relay transmission method and system for pulse width modulation (PWM) coding of urban rail train

Abstract

The invention provides a relay transmission method and system for PWM coding of an urban rail train. The relay transmission method comprises the following steps: step 1, carrying out digital filtering on an input PWM coding signal; 2, judging the transmission direction of the PWM coded signal; step 3, regenerating, amplifying and outputting a PWM coding signal; and step 4, designing safety protection when the relay fails. According to the invention, through a safety protection technology when the relay fails, the problem of effective transmission of PWM coding signals when the relay equipment fails is solved, and the safety characteristic of the system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of urban rail train operation control, and in particular to a relay transmission method and system for PWM coding of an urban rail train. Background Art

[0002] Urban rail transit trains mainly use DC-AC electric locomotives, and their main traction circuits include: DC1500V high-voltage access circuit, traction inverter, traction motor, transmission mechanical device and braking equipment. The train receives current from the DC1500V overhead line, and sends the DC to the traction inverter (VVVF) after passing through the high-speed circuit breaker. The PWM encoder converts the traction and braking control instructions of the driver (controller) or the automatic train control (ATO) into PWM pulse signals and transmits them to the traction and braking control units distributed in each car. The traction inverter (VVVF) inverts the DC1500V DC into three-phase AC with controllable voltage and frequency according to the pulse signal of the PWM encoder, and realizes the traction and braking functions of the train by regulating the speed of the motor.

[0003] At present, PWM coding transmission is mainly transmitted through differential cables, which has the advantages of simplicity, directness, and high efficiency. However, in long-distance transmission, carriage cross-connection, and complex locomotive environments, signal attenuation and electromagnetic interference often occur, which affects the quality of the transmission signal and makes the train unable to run safely and stably. Summary of the invention

[0004] In view of the defects in the prior art, the object of the present invention is to provide a relay transmission method and system for PWM coding of urban rail trains.

[0005] The relay transmission method for urban rail train PWM coding provided by the present invention includes:

[0006] Step 1: Digitally filter the input PWM encoding signal;

[0007] Step 2: Determine the transmission direction of the PWM encoding signal;

[0008] Step 3: Regenerate and amplify the output PWM encoding signal;

[0009] Step 4: Design safety protection against relay failure.

[0010] Preferably, step 1 comprises: using a FIR low-pass filter to filter a PWM coded signal with a frequency of 500 Hz and a duty cycle range of 10% to 90%, wherein the filter parameters are: sampling frequency 1 MHz, passband cutoff frequency 100 KHz, stopband cutoff frequency 200 KHz, stopband attenuation 80 dB, and the filter algorithm is implemented by a 32-bit microprocessor with floating-point computing capability.

[0011] Preferably, step 2 includes: each locomotive A and B on both sides of the train has a PWM encoder for bidirectional operation control, and a PWM encoding repeater is connected between the PWM encoders on both sides of A and B, and simultaneously monitors the travel signals on both sides, and uses the side with the signal as input and the other side as output, thereby realizing bidirectional transmission of the PWM encoding signal.

[0012] Preferably, step 3 comprises: amplifying the output in real time according to the duty cycle of the input PWM coded signal, and performing power amplification on the PWM coded signal by using a push-pull circuit to enhance the anti-interference capability and transmission distance of the signal.

[0013] Preferably, step 4 includes: safety protection design in case of relay failure, including redundancy design, output protection design and relay bypass design;

[0014] The redundant design includes: the coding relay control loop adopts a dual-path redundant design, and the power supply adopts a dual-path redundant design;

[0015] The output protection design includes: adding a feedback detection and judgment mechanism to the relay output, automatically cutting off the output when abnormal feedback is detected, and bypassing the relay output circuit at the same time;

[0016] The relay bypass design includes: the coding relay control loop has a fault detection function, including power supply fault detection, input PWM signal abnormality detection, output feedback detection, and microprocessor operation abnormality detection; when the above fault occurs, the bypass relay is triggered to allow the PWM coding signal to be transmitted directly to the device end without passing through the repeater.

[0017] The relay transmission system for PWM coding of urban rail trains provided by the present invention comprises:

[0018] Module M1: digital filtering of input PWM encoding signal;

[0019] Module M2: Determine the transmission direction of the PWM encoding signal;

[0020] Module M3: regenerates and amplifies the output PWM coded signal;

[0021] Module M4: Designed for safety protection in case of relay failure.

[0022] Preferably, the module M1 includes: using a FIR low-pass filter to filter a PWM encoded signal with a frequency of 500 Hz and a duty cycle range of 10% to 90%, wherein the filter parameters are: sampling frequency 1 MHz, passband cutoff frequency 100 KHz, stopband cutoff frequency 200 KHz, stopband attenuation 80 dB, and the filter algorithm is implemented by a 32-bit microprocessor with floating-point computing capability.

[0023] Preferably, the module M2 includes: each of the locomotives A and B on both sides of the train has a PWM encoder for bidirectional operation control, and a PWM encoding repeater is connected between the PWM encoders on both sides A and B, and simultaneously monitors the travel signals on both sides, and uses the side with the signal as input and the other side as output, thereby realizing bidirectional transmission of PWM encoding signals.

[0024] Preferably, the module M3 comprises: real-time amplification and output according to the duty cycle of the input PWM coded signal, and power amplification of the PWM coded signal by using a push-pull circuit to enhance the anti-interference capability and transmission distance of the signal.

[0025] Preferably, the module M4 includes: a safety protection design in case of relay failure, including a redundancy design, an output protection design and a relay bypass design;

[0026] The redundant design includes: the coding relay control loop adopts a dual-path redundant design, and the power supply adopts a dual-path redundant design;

[0027] The output protection design includes: adding a feedback detection and judgment mechanism to the relay output, automatically cutting off the output when abnormal feedback is detected, and bypassing the relay output circuit at the same time;

[0028] The relay bypass design includes: the coding relay control loop has a fault detection function, including power supply fault detection, input PWM signal abnormality detection, output feedback detection, and microprocessor operation abnormality detection; when the above fault occurs, the bypass relay is triggered to allow the PWM coding signal to be transmitted directly to the device end without passing through the repeater.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention solves the problem that during the transmission of PWM coded signals, signal attenuation and electromagnetic interference may occur, thereby affecting the quality of the transmitted signal and causing the train to be unable to run safely and stably;

[0031] (2) Through the digital filtering technology of the input PWM signal, the problem of electromagnetic interference of the original PWM coded signal during transmission is solved, and the effective extraction of the PWM coded signal is realized;

[0032] (3) The bidirectional transmission of PWM coded signals is ensured by the technology of determining the transmission direction of PWM coded signals, thereby realizing the redundant design of PWM coded signals;

[0033] (4) Through the regenerative amplification technology of the output PWM signal, the signal attenuation problem of the PWM encoded signal during long-distance transmission is solved, ensuring the strength and stability of the terminal receiving signal;

[0034] (5) Through the safety protection technology in case of relay failure, the problem of effective transmission of PWM coded signals can be solved when the relay equipment fails, thereby improving the safety characteristics of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0036] Figure 1 It is a structural schematic diagram of a relay transmission method for PWM coding of urban rail trains according to the present invention;

[0037] Figure 2a and Figure 2b This is the filter simulation effect diagram;

[0038] Figure 3 It is a flow chart for judging the transmission direction of PWM coded signal;

[0039] Figure 4 This is the schematic diagram of the output PWM signal regeneration amplification;

[0040] Figure 5 Schematic diagram of safety protection for repeater output. DETAILED DESCRIPTION

[0041] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0042] Example 1

[0043] The present invention provides a relay transmission method for PWM coding of urban rail trains, comprising: digital filtering design of input PWM signals, judgment of transmission direction of PWM coding signals, regeneration amplification design of output PWM signals, and safety protection design in case of relay failure.

[0044] In the implementation case of the present invention, the detailed design of the PWM signal digital filter is as follows:

[0045] The digital filter design type is FIR low-pass filter, and the design parameters are: sampling frequency 1MHz, passband cutoff frequency 100KHz, stopband cutoff frequency 200KHz, stopband attenuation 80dB; using the Parks-McClellan algorithm, the filter coefficients (hexadecimal) are designed: H[0] = 0x0011, H[1] = 0x005C, H[2] = 0x00FB, H[3] = 0x01CC, H[4] = 0x0242, H[5] = 0x0196, H[6] = 0xFF5D, H[7] = 0xFC48, H[8] = 0xFA55, H[9] = 0xFC05, H

[10] = 0xFC6 10]=0x02D1, H

[11] =0x0DBA, H

[12] =0x192B, H

[13] =0x2080, H

[14] =0x2080, H

[15] =0x192B, H

[16] =0x0DBA, H

[17] =0x02D1, H

[18] =0xFC05, H

[19] =0xFA55, H

[20] =0xFC48, H

[21] =0xFF5D, H

[22] =0x0196, H

[23] =0x0242, H

[24] =0x01CC, H

[25] =0x00FB, H

[26] =0x005C, H

[27] =0x0011. The digital filter implementation formula is: y[n] = x[n]*H[0]+x[n-1]*H[1]+……+x[n-N+1]*H[N-1]; where: y[n] is the filter output, x[n] is the filter input, and N=28 in this filter. The filter simulation effect diagram is shown in Figure 2.

[0046] In the implementation case of the present invention, the structural schematic diagram of the relay transmission method for urban rail train PWM coding is as follows: Figure 1 As shown, the flow chart of PWM coding signal transmission direction determination is as follows Figure 3 As shown. The PWM coding repeater is connected between the encoders on both sides of the train A and B to complete the judgment and control of the transmission direction of the coding signal. After the encoder signal on the A side is relayed and amplified, it is transmitted to the B side, or the signal on the B side is relayed and transmitted to the A side. In the initial state of the PWM coding repeater, the outputs on both sides A and B are disconnected, and the input is in a normally open state. The microprocessor in the repeater monitors the input signals on both sides A and B in real time. After the input signal is processed by digital filtering, the rising edge of the signal triggers the judgment of the transmission direction. When the logic high level is maintained for more than 20us (frequency 500Hz, duty cycle 1%), it is defined as a coding signal input on this side, and the other side is a relay signal output, triggering the output circuit to be turned on, and vice versa. The microprocessor monitors the input signal in real time. When the low level time of the input signal is greater than 2ms, it is considered that the PWM coding signal transmission in this direction is stopped, and the repeater will cut off the output circuit.

[0047] In the implementation case of the present invention, the regeneration amplification principle of the output PWM signal is as follows: Figure 4 As shown. The microprocessor of the repeater generates two signals PWM1 and PWM2 with the same phase, frequency and duty cycle as the input PWM according to the input PWM encoding signal. The PWM1 signal is converted to PWM11 through the inverter IC1, and its phase is opposite to that of PWM1, and the high and low levels of the signal are +5V and 0V respectively; the PWM2 signal is converted to PWM21 through the transistor TR1 and the resistor R1, and its phase is opposite to that of PWM2, and the high and low levels of the signal are +5V and -15V respectively. The PWM11 signal is converted to PWM12 through the buffer IC2, and its phase is the same as that of PWM11, and the high and low levels of the signal are +15V and 0V respectively; the PWM21 signal is converted to PWM22 through the buffer IC3, and its phase is the same as that of PWM21, and the high and low levels of the signal are 0V and -15V respectively. The P-channel MOS tube TR2, the N-channel MOS tube TR3, the resistors R8 and R9 together form a push-pull circuit, the PWM12 signal drives the upper bridge arm TR2 of the push-pull circuit, and the PWM22 signal drives the lower bridge arm TR3 of the push-pull circuit. PWM12 and PWM22 work together to generate the PWM_OUT output signal, which has the same phase, frequency and duty cycle as the input PWM, and its high and low levels are +10V and -15V respectively. Through the above circuit, the power amplification of the PWM encoding signal is realized.

[0048] In the implementation case of the present invention, the safety protection design in case of relay failure mainly includes: redundant design, output protection design and relay bypass design. The relay control circuit and the power supply adopt a dual-path redundant design, which can realize dual-path backup to ensure the reliable output of the system. The relay control circuit has a fault detection function, which includes: power supply fault detection, input PWM signal abnormality detection, output feedback detection, microprocessor operation abnormality detection, etc. The power supply fault detection circuit monitors the key power supply +10V required by the system in real time, and triggers system protection when the power supply is lower than 9V or higher than 11V. The system software program monitors the input PWM signal in real time, and triggers system protection when the signal does not meet the frequency of 500Hz and the duty cycle range of 10% to 90%; at the same time, the system software program performs real-time feedback detection on the PWM encoding signal output by the relay, and triggers system protection when it deviates from the input. The watchdog chip outside the microprocessor is used to monitor the operation of the microprocessor. When abnormal, the watchdog chip outputs a "high" level to trigger system protection. System safety protection is achieved by bypassing the relay output, as shown in the schematic diagram. Figure 5As shown. The safety protection of the system is realized through the relay RL. When the system is in normal state, the protection output is "high" level, the control coil of the relay RL is energized, the normally open contact is turned on, the 11th and 9th pins of RL are turned on, and the output PWM coded signal is the signal after relay processing; when the system fails, the protection output is "low" level, the control coil of the relay RL loses power, the normally open contact is open and the normally closed contact is turned on, and the output PWM coded signal is the coded signal input by the repeater.

[0049] Example 2

[0050] The present invention also provides a relay transmission system for PWM coding of urban rail trains. The relay transmission system for PWM coding of urban rail trains can be implemented by executing the process steps of the relay transmission method for PWM coding of urban rail trains, that is, those skilled in the art can understand the relay transmission method for PWM coding of urban rail trains as a preferred implementation of the relay transmission system for PWM coding of urban rail trains.

[0051] The relay transmission system for PWM coding of urban rail trains provided by the present invention includes: module M1: digital filtering of input PWM coding signals; module M2: determining the transmission direction of PWM coding signals; module M3: regenerating and amplifying output PWM coding signals; module M4: designing safety protection in case of relay failure.

[0052] The module M1 includes: using an FIR low-pass filter to filter a PWM encoded signal with a frequency of 500Hz and a duty cycle range of 10% to 90%, wherein the filter parameters are: sampling frequency 1MHz, passband cutoff frequency 100KHz, stopband cutoff frequency 200KHz, stopband attenuation 80dB, and the filter algorithm is implemented by a 32-bit microprocessor with floating-point computing capability.

[0053] The module M2 includes: each of the A and B locomotives on both sides of the train has a PWM encoder for bidirectional operation control, and the PWM encoding repeater is connected between the PWM encoders on both sides of A and B, and simultaneously monitors the driving signals on both sides, and uses the side with the signal as input and the other side as output, thereby realizing bidirectional transmission of the PWM encoding signal.

[0054] The module M3 includes: real-time amplification and output according to the duty cycle of the input PWM coded signal, and power amplification of the PWM coded signal using a push-pull circuit to enhance the signal's anti-interference capability and transmission distance.

[0055] The module M4 includes: a safety protection design in case of relay failure, including a redundant design, an output protection design and a relay bypass design; the redundant design includes: a dual-path redundant design for the coding relay control circuit, and a dual-path redundant design for the power supply; the output protection design includes: adding a feedback detection and judgment mechanism to the relay output, and when a feedback abnormality is detected, the output is automatically cut off, and the relay output circuit is bypassed at the same time; the relay bypass design includes: the coding relay control circuit has a fault detection function, including power supply fault detection, input PWM signal abnormality detection, output feedback detection, and microprocessor operation abnormality detection; when the above fault occurs, the bypass relay is triggered to transmit the PWM coding signal directly to the device end without passing through the repeater.

[0056] Those skilled in the art know that, in addition to implementing the system, device and its various modules provided by the present invention in a purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers and embedded microcontrollers by logically programming the method steps. Therefore, the system, device and its various modules provided by the present invention can be considered as a hardware component, and the modules included therein for implementing various programs can also be considered as structures within the hardware component; the modules for implementing various functions can also be considered as both software programs for implementing the method and structures within the hardware component.

[0057] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A relay transmission method for urban rail train PWM coding, characterized in that: include: Step 1: Digitally filter the input PWM encoding signal; Step 2: Determine the transmission direction of the PWM encoding signal; Step 3: Regenerate and amplify the output PWM encoding signal; Step 4: Design safety protection against relay failure.

2. The relay transmission method for urban rail train PWM coding according to claim 1, characterized in that: The step 1 comprises: using an FIR low-pass filter to filter a PWM coded signal with a frequency of 500 Hz and a duty cycle range of 10% to 90%, wherein the filter parameters are: sampling frequency 1 MHz, passband cutoff frequency 100 KHz, stopband cutoff frequency 200 KHz, stopband attenuation 80 dB, and the filter algorithm is implemented by a 32-bit microprocessor with floating-point computing capability.

3. The relay transmission method for urban rail train PWM coding according to claim 1, characterized in that: The step 2 includes: each locomotive A and B on both sides of the train has a PWM encoder for bidirectional operation control, and a PWM encoding repeater is connected between the PWM encoders on both sides of A and B, and the driving signals on both sides are monitored simultaneously, and the side with the signal is used as input and the other side as output, so as to realize bidirectional transmission of PWM encoding signals.

4. The relay transmission method for urban rail train PWM coding according to claim 1, characterized in that: The step 3 includes: amplifying the output in real time according to the duty cycle of the input PWM coded signal, and using a push-pull circuit to power amplify the PWM coded signal to enhance the signal's anti-interference capability and transmission distance.

5. The relay transmission method for urban rail train PWM coding according to claim 1, characterized in that: The step 4 includes: safety protection design in case of relay failure, including redundancy design, output protection design and relay bypass design; The redundant design includes: the coding relay control loop adopts a dual-path redundant design, and the power supply adopts a dual-path redundant design; The output protection design includes: adding a feedback detection and judgment mechanism to the relay output, automatically cutting off the output when abnormal feedback is detected, and bypassing the relay output circuit at the same time; The relay bypass design includes: the coding relay control loop has a fault detection function, including power supply fault detection, input PWM signal abnormality detection, output feedback detection, and microprocessor operation abnormality detection; when the above fault occurs, the bypass relay is triggered to allow the PWM coding signal to be transmitted directly to the device end without passing through the repeater.

6. A relay transmission system for PWM coding of urban rail trains, characterized in that: include: Module M1: digital filtering of input PWM encoding signal; Module M2: Determine the transmission direction of the PWM encoding signal; Module M3: regenerates and amplifies the output PWM coded signal; Module M4: Designed for safety protection in case of relay failure.

7. The relay transmission system for urban rail train PWM coding according to claim 6, characterized in that: The module M1 includes: using an FIR low-pass filter to filter a PWM encoded signal with a frequency of 500Hz and a duty cycle range of 10% to 90%, wherein the filter parameters are: sampling frequency 1MHz, passband cutoff frequency 100KHz, stopband cutoff frequency 200KHz, stopband attenuation 80dB, and the filter algorithm is implemented by a 32-bit microprocessor with floating-point computing capability.

8. The relay transmission system for PWM coding of urban rail trains according to claim 6, characterized in that: The module M2 includes: each of the A and B locomotives on both sides of the train has a PWM encoder for bidirectional operation control, and the PWM encoding repeater is connected between the PWM encoders on both sides of A and B, and simultaneously monitors the driving signals on both sides, and uses the side with the signal as input and the other side as output, thereby realizing bidirectional transmission of the PWM encoding signal.

9. The relay transmission system for urban rail train PWM coding according to claim 6, characterized in that: The module M3 includes: real-time amplification and output according to the duty cycle of the input PWM coded signal, and power amplification of the PWM coded signal using a push-pull circuit to enhance the signal's anti-interference capability and transmission distance.

10. The relay transmission system for urban rail train PWM coding according to claim 6, characterized in that: The module M4 includes: safety protection design in case of relay failure, including redundancy design, output protection design and relay bypass design; The redundant design includes: the coding relay control loop adopts a dual-path redundant design, and the power supply adopts a dual-path redundant design; The output protection design includes: adding a feedback detection and judgment mechanism to the relay output, automatically cutting off the output when abnormal feedback is detected, and bypassing the relay output circuit at the same time; The relay bypass design includes: the coding relay control loop has a fault detection function, including power supply fault detection, input PWM signal abnormality detection, output feedback detection, and microprocessor operation abnormality detection; when the above fault occurs, the bypass relay is triggered to allow the PWM coding signal to be transmitted directly to the device end without passing through the repeater.

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