Opening-in circuit capable of self-checking internal and external contacts and applied to direct-current loop

Abstract

The utility model discloses a self-checking internal and external contact input circuit applied to a direct current loop, and effectively solves the problem that a protection system for a double-contact input loop cannot well detect faults of an external input contact and an internal optocoupler. Which comprises an input acquisition circuit arranged in a direct current traction power supply and protection system, and is characterized in that the input acquisition circuit is connected with a self-checking internal and external contact input circuit, and the self-checking internal and external contact input circuit is divided into a self-checking operational amplifier circuit and an internal optocoupler detection circuit; according to the utility model, the structure is ingenious, the use is convenient, through the arrangement of the self-checking internal and external contact switching-in circuit, in a part of important lines such as a subway, aiming at a bilateral power supply switching-in circuit and a switching-in circuit of a previous voltage level, the switching-in circuit can be switched on and switched off according to the level signal receiving condition of the CAN microprocessor; and the adhesion condition of the two external input contacts and the failure condition of the optocoupler circuit are judged, so that the purpose of accurately collecting signals is achieved, and corresponding protection actions are executed.

Description

Technical Field

[0001] The utility model relates to the technical field of direct current power grids, in particular to a self-checking internal and external contact opening circuit applied to a direct current loop. Background Art

[0002] The DC traction power supply and protection system is usually composed of converters, rectifiers and capacitors, which convert AC power into DC power and then provide it to the overhead contact network. The overhead contact network is the part of the DC traction power supply system that contacts the train. It is composed of wires and brackets, usually installed above the railway track, in contact with the pantograph of the train, and transmits electrical energy to the train through the overhead contact network. The DC traction power supply and protection system is an important guarantee for the safe, reliable and stable operation of the subway.

[0003] The DC protection device needs to collect dynamic signals of all external contacts during the open-loop operation, and perform corresponding protection actions through signal feedback. At present, most of the power supply methods of DC power grids are bilateral power supply methods. This power supply method determines that once a short circuit occurs between the contact grid and the ground, the power supply circuit switches of the two stations on both sides need to be cut off at the same time. This requires that the devices with bilateral power supply can collect contact open-loop signals from each other. The correct collection of this important signal is related to the safe operation of the entire power grid.

[0004] In the currently existing DC traction power supply and protection system, a double-contact input circuit must be used for the bilateral power supply input circuit and the input circuit of the upper voltage level. However, the existing protection system for the double-contact input circuit cannot well detect faults of the external input contacts and the internal optocoupler. Utility Model Content

[0005] In view of the above situation, in order to overcome the defects of the prior art, the purpose of the utility model is to provide a self-checking internal and external contact opening circuit for DC circuit, which effectively solves the problems mentioned in the background technology.

[0006] The technical solution is that the utility model includes an open-in acquisition circuit arranged in a DC traction power supply and protection system, characterized in that the open-in acquisition circuit is connected to a self-checking internal and external contact open-in circuit, and the self-checking internal and external contact open-in circuit is divided into a self-checking operational amplifier circuit and an internal optocoupler detection circuit;

[0007] The open-in acquisition circuit is composed of two external open-in contacts CB1 and CB2, a primary surge protection circuit Y1, a local circuit of the first voltage-dividing resistors R11\R12\R13\R14, a secondary protection circuit varistor Y2, a discharge tube TVS1, a current-limiting resistor R15, a first direction diode circuit, a first photocoupler OP1 and a CAN microprocessor;

[0008] The self-test operational amplifier circuit is composed of a primary surge protection circuit Y3 connected in parallel to the open-input acquisition circuit, a local circuit of the second voltage-dividing resistors R21\R22\R24, a filter circuit inductor L1, a capacitor C1 and a negative feedback operational amplifier circuit; the internal optocoupler detection circuit is composed of a local circuit of a current-limiting resistor R16 connected in parallel to the open-input acquisition loop, an isolated power supply VCC, a second directional diode circuit and a second photocoupler OP2, and the self-test operational amplifier circuit is connected in series with the internal optocoupler detection circuit.

[0009] Preferably, the negative feedback operational discharge circuit is composed of an operational amplifier U1 and a resistor R23 connected in parallel.

[0010] Preferably, the first directional diode circuit is composed of a first directional diode D1 and a second directional diode D2.

[0011] Preferably, the second directional diode circuit is composed of a third directional diode D3 and a fourth directional diode D4.

[0012] Preferably, the external contact self-test operational amplifier circuit is connected in parallel with the open-input acquisition circuit.

[0013] Preferably, the two external open-in contacts CB1 and CB2 are respectively connected to the positive circuit and the negative circuit of the first photocoupler.

[0014] Preferably, the local circuit of the current limiting resistor R16, the isolated power supply VCC, the second directional diode circuit and the second photocoupler OP2 are connected in series with each other.

[0015] Preferably, the first voltage-dividing resistors R11\R12\R13\R14 are connected in parallel in pairs, and two of the second voltage-dividing resistors R21\R22\R24 are connected in parallel with one of the voltage-dividing resistors.

[0016] Compared with the prior art, the beneficial effects of the utility model are:

[0017] Through the setting of self-checking internal and external contact input circuits, in some important lines such as subways, for the bilateral power supply input circuit and the input circuit of the previous voltage level, the adhesion of the two external input contacts and the failure of the optocoupler circuit can be judged according to the level signal received by the CAN microprocessor, so as to achieve the purpose of accurately collecting signals. After a short circuit occurs to the ground in the contact grid, the power supply circuit switches of the two stations on both sides are closed at the same time, and the corresponding protection actions are performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a principle diagram of the open-input acquisition circuit in the utility model.

[0019] Figure 2 It is a principle diagram of the self-checking internal and external contact opening circuit in the utility model.

[0020] Figure 3 The utility model is a flow chart of the opening self-checking. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0022] Depend on Figures 1 to 3 The invention provides an open-in acquisition circuit provided in a DC traction power supply and protection system, wherein the open-in acquisition circuit is respectively connected with an external contact self-test operational amplifier circuit and an internal optocoupler self-test circuit, the external contact self-test operational amplifier circuit is connected in parallel with the open-in acquisition circuit, the open-in acquisition circuit is composed of two external open-in contacts CB1 and CB2, a primary surge protection circuit Y1, a local circuit of a first voltage-dividing resistor R11\R12\R13\R14, a secondary protection circuit varistor Y2, a discharge tube TVS1, a current-limiting resistor R15, a first direction diode circuit, a first photocoupler OP1 and a CAN microprocessor, the first voltage-dividing resistors R11\R12\R13\R14 are connected in parallel in pairs, the first direction diode circuit is composed of a first direction diode D1 and a second direction diode D2, and the two external open-in contacts CB1 and CB2 are respectively connected with the positive circuit and the negative circuit of the first photocoupler OP1;

[0023] The external contact self-test operational discharge circuit is composed of a primary surge protection circuit Y3, a partial circuit of voltage-dividing resistors R21 / R22 / R24, a filter circuit inductor L1, a capacitor C1 and a negative feedback operational amplifier circuit. The negative feedback operational discharge circuit is composed of an operational amplifier U1 and a resistor R23 in parallel. The internal optocoupler self-test circuit is composed of a partial circuit of a current-limiting resistor R16, an isolated power supply VCC, a second direction diode circuit and a second optocoupler OP2. The partial circuit of the current-limiting resistor R16, the isolated power supply VCC, the second direction diode circuit and the second optocoupler OP2 are connected in series with each other. The second direction diode circuit is composed of a third direction diode D3 and a fourth direction diode D4. The self-test operational amplifier circuit is connected in series with the internal optocoupler detection circuit. The second voltage-dividing resistors R21\R22\R24 are connected in series with each other. Two voltage-dividing resistors are connected in parallel with one of the voltage-dividing resistors. Through the setting of two first-level surge protection circuits Y1 and Y3, large energy interference sources can be discharged in time to protect the internal resistors and other components of the subsequent stage. The inductor L1 and capacitor C1 of the filter circuit can quickly discharge high-frequency interference energy. With the setting of two discharge tubes TVS1 and TVS2, the peak pulse energy can be quickly discharged to protect the subsequent circuit. The setting of the third-directional diode D3 can prevent the CB2 contact level from interfering with the external contact self-test operational amplifier circuit, and the setting of the fourth-directional diode D4 can prevent the CB1 contact level from interfering with the external contact self-test operational amplifier circuit. With the setting of the current-limiting resistor R16, the loop current of the isolated power supply VCC can be effectively limited to ensure the power supply power of the overall circuit.

[0024] Embodiment 1:

[0025] When there is no adhesion between the two external open-in contacts CB1 and CB2 and no failure of the two photoelectric couplers OP1 and OP2, when the external open-in contact CB1 is closed, the open-in signal voltage passes through the local circuit of the first voltage-dividing resistors R11\R12\R13\R14 and the subsequent circuit of the open-in acquisition circuit, and outputs a high level to the positive terminal of the first photoelectric coupler OP1. When the external contact CB2 is closed, the open-in signal voltage passes through the local circuit of the voltage-dividing resistors R21\R22\R24 to reach the negative terminal of the operational amplifier U1. At this time, the operational amplifier U1 outputs a low level to the negative terminal of OP1, thereby finally turning on the first photoelectric coupler OP1.

[0026] Embodiment 2:

[0027] When the external open-in contact CB1 is closed and CB2 is normal, when CB1 is closed, the open-in level signal reaches the positive terminal of the first photocoupler OP1 through the open-in acquisition circuit, and the positive terminal of the first photocoupler OP1 is at a high level. When the external open-in contact CB2 is closed, the open-in level signal reaches the negative terminal of the first photocoupler OP1 through the negative feedback amplifier circuit, and the positive and negative terminals of the photocoupler OP1 are both at low levels, so that the first photocoupler OP1 is turned on, and the CAN microprocessor can normally collect the open-in signal.

[0028] However, when the external input contact CB2 is disconnected, the input level signal reaches the negative terminal of the first photocoupler OP1 through the negative feedback operational amplifier circuit. At this time, the positive and negative terminals of the optocoupler OP1 are both high level, so the first photocoupler OP1 is not turned on, and the CAN microprocessor cannot collect the input signal normally.

[0029] Embodiment 3:

[0030] When the external input contact CB2 is closed and the external input contact CB1 is normal, after CB2 is closed, the input level signal reaches the negative terminal of the optocoupler OP1 through the negative feedback amplifier circuit, and its negative terminal is at a low level. When CB1 is closed normally, a high level signal reaches the positive terminal of the first photocoupler OP1, and the first photocoupler OP1 is normally turned on, and the CAN microprocessor can normally collect the input signal.

[0031] However, when the external input contact CB1 is normally disconnected, no level signal reaches the positive terminal of the first photocoupler OP1, and its positive terminal is at a low level, causing both the positive and negative terminals of the first photocoupler OP1 to be at a low level, so that the first photocoupler OP1 is not conducting.

[0032] Embodiment 4:

[0033] When the two external input contacts CB1\CB2 are normal and the first photocoupler OP1 fails, all its input signals cannot be transmitted to the CAN communication chip. When the CAN communication chip turns on the optocoupler OP2, a high-level signal reaches the positive terminal of the first photocoupler OP1. At this time, the optocoupler OP1 fails and cannot be turned on. CAN cannot collect the input signal, and it can be determined that the first photocoupler OP1 has failed.

[0034] Embodiment 5:

[0035] When the two external input contacts CB1\CB2 are normal and the second photocoupler OP2 fails, the CAN microprocessor cannot make the input level signal of the isolated power supply VCC reach the optocoupler OP1, so that the OP1 optocoupler has no signal collection, and thus the CAN cannot collect the input signal, which can be judged as the optocoupler OP2 failure.

[0036] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A self-checking internal and external contact input circuit for a DC circuit, comprising an input acquisition circuit arranged in a DC traction power supply and protection system, characterized in that: The open-in acquisition circuit is connected to a self-checking internal and external contact open-in circuit, and the self-checking internal and external contact open-in circuit is divided into a self-checking operational amplifier circuit and an internal optocoupler detection circuit; The open-in acquisition circuit is composed of two external open-in contacts CB1 and CB2, a primary surge protection circuit Y1, a local circuit of the first voltage-dividing resistors R11\R12\R13\R14, a secondary protection circuit varistor Y2, a discharge tube TVS1, a current-limiting resistor R15, a first direction diode circuit, a first photocoupler OP1 and a CAN microprocessor; The self-test operational amplifier circuit is composed of a primary surge protection circuit Y3 connected in parallel to the open-input acquisition circuit, a local circuit of the second voltage-dividing resistors R21\R22\R24, a filter circuit inductor L1, a capacitor C1 and a negative feedback operational amplifier circuit; the internal optocoupler detection circuit is composed of a local circuit of a current-limiting resistor R16 connected in parallel to the open-input acquisition loop, an isolated power supply VCC, a second directional diode circuit and a second photocoupler OP2, and the self-test operational amplifier circuit is connected in series with the internal optocoupler detection circuit.

2. A self-checking internal and external contact input circuit for a DC circuit according to claim 1, characterized in that: The negative feedback operational discharge circuit is composed of an operational amplifier U1 and a resistor R23 connected in parallel.

3. A self-checking internal and external contact input circuit for a DC circuit according to claim 1, characterized in that: The first directional diode circuit is composed of a first directional diode D1 and a second directional diode D2.

4. A self-checking internal and external contact input circuit for a DC circuit according to claim 1, characterized in that: The second directional diode circuit is composed of a third directional diode D3 and a fourth directional diode D4.

5. The self-checking internal and external contact input circuit for DC circuit according to claim 1, characterized in that: The external contact self-checking operational amplifier circuit is connected in parallel with the open-input acquisition circuit.

6. A self-checking internal and external contact input circuit for a DC circuit according to claim 1, characterized in that: The two external open-in contacts CB1 and CB2 are respectively connected to the positive circuit and the negative circuit of the first photocoupler OP1.

7. A self-checking internal and external contact input circuit for a DC circuit according to claim 1, characterized in that: The local circuit of the current limiting resistor R16, the isolated power supply VCC, the second directional diode circuit and the second photocoupler OP2 are connected in series with each other.

8. The self-checking internal and external contact input circuit for DC circuit according to claim 1, characterized in that: The first voltage-dividing resistors R11\R12\R13\R14 are connected in parallel in pairs, and two of the second voltage-dividing resistors R21\R22\R24 are connected in parallel with one of the voltage-dividing resistors.

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