Input interface circuit

Abstract

The invention provides an input interface circuit. A relay contact is connected with the input end of a controller through an input interface, a conditioning control circuit and a first isolation module in sequence; and input signals of the relay contact contacts can be collected to the controller. The output end of the controller is connected with the control end of the conditioning control circuit through a second isolation module and outputs a wetting current control signal; the conditioning control circuit can control the input interface to be short-circuited to the ground according to the duty ratio of the wetting current control signal when the input interface transmits a high-level acquisition signal; and when the duty ratio is greater than a preset value, taking a corresponding pulse short-circuit current formed on the input interface as a wetting current, and cleaning the relay contact. Therefore, the integrated design of relay contact cleaning and input interface signal acquisition can be realized, and the problems of low working reliability and high cost of equipment in an automation scheme in the prior art are avoided.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and particularly to an input interface circuit. Background Art

[0002] In the field of rail transit, a large number of signal relays are applied to train on-vehicle signal equipment and signal mechanical rooms, and are mostly used for functions such as signal transmission and status detection, which play a crucial role in the safe operation of trains. In actual applications, the reliable contact of the relay contact is an important manifestation of the relay performance. However, due to environmental factors, including but not limited to factors such as air humidity, temperature, and floating solid pollutants, the relay contact may be corroded or contaminated, resulting in its inability to make reliable contact, affecting signal transmission and detection. Therefore, it is necessary to clean the relay contact.

[0003] The general treatment method is to apply a pulsed current signal, i.e., a wetting current, to the relay signal path to cause arcing at the relay contact, thereby achieving the purpose of cleaning the relay contact. The system usually uses an input interface circuit to collect the node signal status of the relay. Since the wetting current is a pulsed current signal with a large current value, it may damage the input interface circuit. Therefore, the cleaning of the relay contact may conflict with the input interface circuit.

[0004] In the prior art, when manually cleaning the relay contact, the connection between the input interface circuit and the relay is first disconnected, and then the wetting current cleaning device is connected to the relay to achieve the cleaning of the relay contact; this solution is cumbersome to operate and requires regular manual intervention, and cannot achieve automatic control. There is also an automatic solution in the prior art, which is to design a wetting current control circuit while designing the input interface circuit, as Figure 1 shown; the software periodically controls the switch action to connect the wetting current control circuit to the relay and disconnect it from the input interface circuit at the same time; after the cleaning is completed, the relay is connected to the input interface circuit again; however, this solution requires designing two circuit modules, and the circuit switching will result in low working reliability and high cost of the equipment. Summary of the Invention

[0005] In view of this, this application provides an input interface circuit to achieve an integrated design for cleaning the relay contact and collecting the input interface signal.

[0006] To achieve the above object, this application provides the following technical solutions:

[0007] This application provides an input interface circuit, including: an input interface, a controller, a conditioning control circuit, a first isolation module, and a second isolation module; wherein,

[0008] The outer side of the input interface is used to connect to the relay contact point;

[0009] The inner side of the input interface is connected to the input end of the controller through the conditioning control circuit and the first isolation module in sequence;

[0010] The output end of the controller is connected to the control end of the conditioning control circuit through the second isolation module and outputs a wetting current control signal;

[0011] The conditioning control circuit is used to control the input interface to be short-circuited to ground according to the duty cycle of the wetting current control signal when a high-level acquisition signal is transmitted through the input interface; and when the duty cycle is greater than a preset value, the corresponding pulse short-circuit current formed on the input interface is used as the wetting current to clean the relay contact point.

[0012] Optionally, the conditioning control circuit includes: an acquisition circuit, a switching tube, and a control circuit; where

[0013] The input end of the acquisition circuit is connected to the inner side of the input interface;

[0014] The output end of the acquisition circuit is connected to the input end of the controller through the first isolation module;

[0015] The switching tube and the current-limiting resistor are connected in series between the inner side of the input interface and the ground;

[0016] The control end of the switching tube is connected to the output end of the controller through the control circuit and the second isolation module in sequence.

[0017] Optionally, the acquisition circuit includes: a first resistor, a second resistor, a third resistor, and a first comparator; where

[0018] The inner side of the input interface is grounded through the first resistor, the second resistor, and the third resistor in sequence;

[0019] The connection point of the second resistor and the third resistor is connected to the non-inverting input end of the first comparator;

[0020] The inverting input end of the first comparator receives a first reference voltage;

[0021] The output end of the first comparator serves as the output end of the acquisition circuit.

[0022] Optionally, the control circuit includes: a conditioning module, a second comparator, a first diode, and a second diode; where

[0023] The conditioning module is configured to receive the wetting current control signal through the first isolation module and generate an excitation control signal based on it;

[0024] The non-inverting input terminal of the second comparator receives the excitation control signal;

[0025] The inverting input terminal of the second comparator receives a second reference voltage;

[0026] The output terminal of the second comparator is respectively connected to the negative electrode of the first diode and the control terminal of the switching tube;

[0027] The positive electrodes of the first diode and the second diode are both connected to the connection point of the first resistor and the second resistor;

[0028] The negative electrode of the second diode is connected to the power supply.

[0029] Optionally, the switching tube is a field effect transistor.

[0030] Optionally, the input terminal of the switching tube is connected to the inner side of the input interface;

[0031] The output terminal of the switching tube is connected to one end of the current limiting resistor;

[0032] The other end of the current limiting resistor is grounded.

[0033] Optionally, the first isolation module is an opto-isolation module.

[0034] Optionally, the second isolation module is an opto-isolation module.

[0035] Optionally, the controller is a microcontroller unit MCU.

[0036] For the input interface circuit provided in this application, the outer side of its input interface is used to connect the relay contact, and the inner side of its input interface is sequentially connected to the input terminal of the controller through the conditioning control circuit and the first isolation module; thus, the input signal of the relay contact can be collected to the controller. In addition, the output terminal of the controller is connected to the control terminal of the conditioning control circuit through the second isolation module and outputs a wetting current control signal; when the conditioning control circuit transmits a high-level acquisition signal at the input interface, it can control the input interface to be shorted to ground according to the duty cycle of the wetting current control signal; moreover, when the duty cycle is greater than a preset value, the corresponding pulsed short-circuit current formed at the input interface can be used as the wetting current to clean the relay contact. Therefore, this application can achieve an integrated design for cleaning the relay contact and collecting the input interface signal, without the need to switch back and forth and design additional circuits for wetting current testing, avoiding the problems of low working reliability and high cost of the equipment in the existing automation solutions. Brief Description of the Drawings

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0038] Figure 1 Structural schematic diagram of an automated solution for cleaning relay contact points provided by the prior art;

[0039] Figure 2 Structural schematic diagram of the input interface circuit provided by the embodiment of the present application;

[0040] Figure 3 A specific structural schematic diagram of the input interface circuit provided by the embodiment of the present application;

[0041] Figure 4 Circuit diagram of the conditioning control circuit in the input interface circuit provided by the embodiment of the present application;

[0042] Figure 5 Optional waveform schematic diagram of the wetting current control signal provided by the embodiment of the present application. Detailed Description of the Embodiments

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0044] In this application, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, the element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including the element.

[0045] This application provides an input interface circuit to achieve an integrated design for cleaning relay contact points and collecting input interface signals.

[0046] See Figure 2, the input interface circuit includes: an input interface 10, a controller 40, a conditioning control circuit 20, a first isolation module 30, and a second isolation module 50; where:

[0047] The outer side of the input interface 10 is used to connect to the relay contact. The inner side of the input interface 10 is connected to the input end of the controller 40 through the conditioning control circuit 20 and the first isolation module 30 in sequence.

[0048] The output end of the controller 40 is connected to the control end of the conditioning control circuit 20 through the second isolation module 50.

[0049] Since the input signals of the relay contacts connected to the input interface 10 are mostly high-voltage level signals, which can reach more than one hundred volts in actual applications, isolation design is adopted for the control and acquisition signals in the system. In actual applications, the first isolation module 30 can adopt an optoelectronic isolation module, such as an optocoupler isolator, but is not limited to this; the second isolation module 50 can also adopt an optoelectronic isolation module, such as an optocoupler isolator, and is not limited to this; both can be determined according to their specific application environments, as long as they can achieve the isolation output and acquisition of signals, and other implementation forms in the prior art are also within the protection scope of this application.

[0050] In addition, the controller 40 can specifically be implemented by an MCU (Microcontroller Unit), but is not limited to this.

[0051] The specific working principle is as follows:

[0052] The input interface 10 transmits the input signal of the relay contact through the conditioning control circuit 20, and then after being isolated by the first isolation module 30, it is given to the controller 40 to complete the acquisition of the input signal of the relay contact.

[0053] When it is necessary to clean the relay contact, the software in the controller 40 can control the generation of a wetting current control signal, which is given to the conditioning control circuit 20 through the second isolation module 50. The second isolation module 50 is used to isolate the digital signal circuit in the controller 40 and the conditioning control circuit 20 to prevent the influence and interference of external circuits.

[0054] The conditioning control circuit 20 is used to control the input interface 10 to be short-circuited to the ground according to the duty cycle of the wetting current control signal when the input interface 10 transmits a high-level acquisition signal; and when the duty cycle is greater than the preset value, the corresponding pulse short-circuit current formed by the input interface 10 is used as the wetting current to clean the relay contact.

[0055] Specifically, a switch capable of controlling the short circuit of the control input interface 10 can be provided inside the conditioning control circuit 20. The opening and closing of the switch are controlled by a wetting current control signal, so as to generate a wetting current in the path between the input interface 10 and the relay contact.

[0056] The wetting current control signal is specifically a pulse signal, and the duty cycle of the level that controls the closing of the switch is adjustable, so as to adjust the duration of the input interface 10 being shorted to ground within the pulse period, and further change the equivalent current magnitude of the pulse short-circuit current formed on the input interface 10. When the duty cycle is greater than the above preset value, the pulse short-circuit current reaches the minimum current capable of maintaining a small arc at the relay contact, and further can be used as the wetting current to remove the dust and corrosion on the surface of the relay contact, so as to keep the relay contact in the best working state. The value of the preset value is not limited, as long as it can clean the relay contact.

[0057] In the input interface circuit provided in this embodiment, the relay contact can be connected to the input end of the controller 40 through the input interface 10, the conditioning control circuit 20 and the first isolation module 30 in sequence, so that the input signal of the relay contact can be collected by the controller 40. In addition, the output end of the controller 40 outputs a wetting current control signal to the conditioning control circuit 20 through the second isolation module 50, so that when the conditioning control circuit 20 transmits a high-level acquisition signal at the input interface 10, it can control the input interface 10 to be shorted to ground according to the duty cycle of the wetting current control signal; moreover, when the duty cycle is greater than the preset value, the corresponding pulse short-circuit current formed on the input interface 10 can be used as the wetting current to clean the relay contact. Therefore, this embodiment not only realizes the automatic control of the wetting current, but also can realize the integrated design of the cleaning of the relay contact and the signal acquisition of the input interface 10, without switching back and forth and designing additional circuits for wetting current testing, avoiding the problems of low working reliability and high cost of the equipment in the existing automatic solutions.

[0058] On the basis of the previous embodiment, some specific examples of the implementation structure of the conditioning control circuit 20 in the input interface circuit are given in this embodiment. For example, see Figure 3 The conditioning control circuit 20 includes: an acquisition circuit 201, a switching transistor Q0 and a control circuit 202; where:

[0059] The input end of the acquisition circuit 201 is connected to the inner side of the input interface 10.

[0060] The output end of the acquisition circuit 201 is connected to the input end of the controller 40 through the first isolation module 30.

[0061] The switching transistor Q0, as the switch provided inside the conditioning control circuit 20 in the above embodiment, is connected in series with the current-limiting resistor R0 between the inside of the input interface 10 and the ground. The function of the current-limiting resistor R0 is to limit the short-circuit current when the switching transistor Q0 is turned on. Specifically, as Figure 3 shown in, the input end of the switching transistor Q0 is connected to the inside of the input interface 10, the output end of the switching transistor Q0 is connected to one end of the current-limiting resistor R0, and the other end of the current-limiting resistor R0 is grounded; in practical applications, the series connection order between the switching transistor Q0 and the current-limiting resistor R0 can also be interchanged, which will not be elaborated and shown here, and it can be determined according to its specific application environment, and all are within the protection scope of this application.

[0062] The control end of the switching transistor Q0 is connected to the output end of the controller 40 through the control circuit 202 and the second isolation module 50 in sequence. That is, the wetting current control signal output by the controller 40 is transmitted through the isolation of the second isolation module 50 and then transmitted to the control end of the switching transistor Q0 through the control circuit 202.

[0063] In one example, the switching transistor Q0 can specifically adopt a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), but it is not limited thereto, and it can be determined according to its specific application environment.

[0064] In practical applications, as Figure 4 shown in, the acquisition circuit 201 can specifically include: a first resistor R1, a second resistor R2, a third resistor R3, and a first comparator U1; where: the inside of the input interface 10 is grounded through the first resistor R1, the second resistor R2, and the third resistor R3 in sequence; the connection point of the second resistor R2 and the third resistor R3 is connected to the non-inverting input end of the first comparator U1 (such as the Y pin inside U1 shown in Figure 4 ); the inverting input end of the first comparator U1 (such as the X pin inside U1 shown in Figure 4 ) receives the first reference voltage V1; the output end of the first comparator U1, as the output end of the acquisition circuit 201, is connected to the input end of the controller 40 through the first isolation module 30 shown in Figure 2 .

[0065] Since the input signal of the relay contact connected to the input interface 10 generally has a relatively high level voltage, up to hundreds of volts, it is generally not used directly and needs to be divided. Therefore, through the first resistor R1, the second resistor R2, and the third resistor R3, resistance voltage division and current limiting are performed for the non-inverting input end of the first comparator U1 (such as Figure 4The Y pin within U1 shown in [figure] provides the input. The resistance values of the first resistor R1, the second resistor R2, and the third resistor R3 can be set according to the specific level of the input signal received by the input interface 10, which is not limited here.

[0066] In addition, as Figure 4 shown, the control circuit 202 may specifically include: a conditioning module, a second comparator U2, a first diode D1, and a second diode D2; where: the conditioning module is configured to receive the wetting current control signal through the first isolation module 30 and generate an excitation control signal according to the wetting current control signal; the non-inverting input terminal of the second comparator U2 (such as Figure 4 the Y pin within U2 shown in [figure]) receives the excitation control signal; the inverting input terminal of the second comparator U2 (such as Figure 4 the X pin within U2 shown in [figure]) receives the second reference voltage V2; the output terminal of the second comparator U2 is respectively connected to the negative electrode of the first diode D1 and the control terminal of the switching transistor Q0; the positive electrodes of the first diode D1 and the second diode D2 are both connected to the connection point of the first resistor R1 and the second resistor R2; the negative electrode of the second diode D2 is connected to the power supply VCCD.

[0067] In the control circuit 202, by utilizing the unidirectional conduction characteristics of the first diode D1 and the second diode D2, the potential at the connection of the first resistor R1 and the second resistor R2 can be clamped. Ignoring the diode conduction voltage, the voltage at this connection can be switched between the voltage of the power supply VCCD and 0 volts, ensuring that the voltage received by the non-inverting input terminal of the first comparator U1 (such as Figure 4 the Y pin within U1 shown in [figure]) is switched between two fixed values.

[0068] The above-mentioned first reference voltage V1 and second reference voltage V2 are generally realized by resistor voltage division, and their specific values can be determined according to actual needs respectively, which is not limited here.

[0069] Combined with Figure 4 , the working principle of the conditioning control circuit 20 is as follows:

[0070] The conditioning module generates an excitation control signal according to the wetting current control signal, and then the excitation control signal and the first reference voltage V1 are compared by the second comparator U2 to generate a level control signal, thereby controlling the conduction or cutoff of the switching transistor Q0.

[0071] When the switching transistor Q0 is turned on, the input interface 10 is shorted to the ground, and a short-circuit current signal with a relatively large current value will be generated in the path where the input interface 10 is located; when the switching transistor Q0 is turned off, such a short-circuit current signal will not be generated in this path. The wetting current control signal is a pulse signal, which can periodically control the conduction and cutoff of the switching transistor Q0. Therefore, by adjusting the duty cycle of the wetting current control signal, that is, the pulse width, the conduction time of the switching transistor Q0 can be controlled, and at the same time, the equivalent current of this path is also adjusted. Since the wetting current is the minimum current that can maintain a small arc at the contact of the device, the duty cycle can be controlled to be greater than a preset value to increase the conduction time of the switching transistor Q0, thereby generating the wetting current.

[0072] As Figure 5 shown, when wetting current is required to clean the above path, the wetting current control signal is set to the wetting current pulse T2, corresponding to a relatively large duty cycle; when the input signal of the input interface 10 needs to be collected, the wetting current control signal can be set to the acquisition pulse T1, corresponding to a relatively small duty cycle. For example, when the duty cycle is less than a relatively small threshold value and the equivalent current of the above path can be ignored, the input signal can be collected.

[0073] The first comparator U1 is used to collect the input signal received by the input interface 10. When the input signal is a low-level signal, the output of the first comparator U1 is also a low level.

[0074] When the input signal is a high-level signal, under the action of the first diode D1 and the second diode D2, the outputs of the first comparator U1 and the second comparator U2 are made consistent. And the output of the second comparator U2 is controlled by the wetting current control signal. Therefore, when the input signal is a high-level signal, the output of the first comparator U1 is controlled by the wetting current control signal.

[0075] To achieve an integrated design of wetting current control and input signal acquisition, when collecting the input signal, the wetting current control signal is designed as a high-frequency continuous pulse signal. When the input signal is at a low level, the output of the first comparator U1 is at a low level. At this time, the controller 40 can determine that the input signal is at a low level; when the input signal is at a high level, the output of the first comparator U1 is a continuous pulse signal. At this time, the controller 40 can determine that the input signal is at a high level.

[0076] In this embodiment, the controller 40 generates a wetting current control signal, which is finally reflected in a series of pulse current signals generated on the input interface circuit, thereby forming a wetting current to achieve the effect of cleaning the relay contact, and improving the reliability of the relay device operation. Moreover, the control of the wetting current and the acquisition of the input signal are integrated in a clever design. There is no need to switch back and forth and design an additional circuit for the wetting current test. The corresponding functions can be achieved only by software control. In addition, the circuit is simple, the control is simple and convenient, the reliability is strong, and the cost is low.

[0077] For the same or similar parts among the embodiments in this specification, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for a system or a system embodiment, since it is basically similar to a method embodiment, the description is relatively simple. For the relevant parts, reference can be made to the partial description of the method embodiment. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without creative work.

[0078] Those skilled in the art can further realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed in this article can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0079] For the above description of the disclosed embodiments, the features recorded in each embodiment in this specification can be replaced or combined with each other, enabling those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An input interface circuit, characterized in that, it includes: an input interface, a controller, a conditioning control circuit, a first isolation module and a second isolation module; wherein, the outside of the input interface is used to connect the relay contact; the inside of the input interface is connected to the input end of the controller through the conditioning control circuit and the first isolation module in sequence; the output end of the controller is connected to the control end of the conditioning control circuit through the second isolation module and outputs a wetting current control signal; the conditioning control circuit is used to control the input interface to be short-circuited to ground according to the duty ratio of the wetting current control signal when the input interface transmits a high-level acquisition signal; and when the duty ratio is greater than a preset value, the corresponding pulse short-circuit current formed by the input interface is used as the wetting current to clean the relay contact.

2. The input interface circuit according to claim 1, characterized in that, the conditioning control circuit includes: an acquisition circuit, a switching tube and a control circuit; wherein, the input end of the acquisition circuit is connected to the inside of the input interface; the output end of the acquisition circuit is connected to the input end of the controller through the first isolation module; the switching tube and the current-limiting resistor are connected in series between the inside of the input interface and the ground; the control end of the switching tube is connected to the output end of the controller through the control circuit and the second isolation module in sequence.

3. The input interface circuit according to claim 2, characterized in that, the acquisition circuit includes: a first resistor, a second resistor, a third resistor and a first comparator; wherein, the inside of the input interface is grounded through the first resistor, the second resistor and the third resistor in sequence; the connection point of the second resistor and the third resistor is connected to the non-inverting input end of the first comparator; the inverting input end of the first comparator receives a first reference voltage; the output end of the first comparator serves as the output end of the acquisition circuit.

4. The input interface circuit according to claim 3, characterized in that, the control circuit includes: a conditioning module, a second comparator, a first diode and a second diode; wherein, the conditioning module is used to receive the wetting current control signal through the first isolation module and generate an excitation control signal according to it; the non-inverting input end of the second comparator receives the excitation control signal; the inverting input end of the second comparator receives a second reference voltage; the output end of the second comparator is respectively connected to the negative electrode of the first diode and the control end of the switching tube; the positive electrodes of the first diode and the second diode are both connected to the connection point of the first resistor and the second resistor; the negative electrode of the second diode is connected to the power supply.

5. The input interface circuit according to claim 2, characterized in that, the switching tube is a field effect transistor.

6. The input interface circuit according to claim 2, characterized in that, the input end of the switching tube is connected to the inside of the input interface; the output end of the switching tube is connected to one end of the current-limiting resistor; The other end of the current-limiting resistor is grounded.

7. The input interface circuit according to any one of claims 1 to 6, characterized in that the first isolation module is an opto-isolation module.

8. The input interface circuit according to any one of claims 1 to 6, characterized in that the second isolation module is an opto-isolation module.

9. The input interface circuit according to any one of claims 1 to 6, characterized in that the controller is a microcontroller unit MCU.

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