A filament current acquisition device for rail traffic signal lamp

Abstract

The present invention discloses a filament current acquisition device for a rail transit signal lamp, comprising an external signal source, an internal signal source, a current signal acquisition channel, a CPU and a mutually exclusive relay. The input end of the CPU is connected to the output end of the current signal acquisition channel; the output end of the CPU is connected to the input end of the internal signal source; the two ends of the first normally open contact of the mutually exclusive relay are respectively connected to the live wire end of the external signal source and the input positive end of the current signal acquisition channel; the two ends of the second normally open contact are respectively connected to the neutral wire end of the external signal source and the input negative end of the current signal acquisition channel; the two ends of the first normally closed contact are respectively connected to the positive end of the internal signal source and the input positive end of the current signal acquisition channel; the two ends of the second normally closed contact are respectively connected to the neutral wire end of the internal signal source and the input negative end of the current signal acquisition channel; the two ends of the third normally closed contact are respectively connected to the positive end of the internal digital power supply and the feedback signal input end of the CPU. The present invention can reliably acquire filament current.

Description

Technical Field

[0001] The present invention relates to a filament current acquisition device for rail transit signal lights. Background Art

[0002] A signal machine is an important device in the rail transit interlocking system, and it needs to be driven safely and reliably and the lighting state needs to be acquired. The lighting state is judged by collecting the magnitude of the current in the signal light loop. Therefore, a reliable filament current acquisition circuit is a prerequisite for ensuring accurate acquisition of the filament current.

[0003] The traditional method for acquiring the signal lamp current is as follows: After the filament current signal passes through an isolation circuit and a filter conditioning circuit, an analog-to-digital conversion chip converts the analog signal into a digital signal and sends it to the CPU for reading, and the CPU judges the lighting condition of the signal lamp. In order to ensure the accuracy of the acquired current, the traditional solution adopts a redundant control strategy, that is, the consistency of the acquisition results of two channels is used to reduce the misjudgment problem caused by the current acquisition error caused by the abnormality of a single acquisition channel. However, once an abnormal acquisition occurs, it is impossible to distinguish whether it is a misacquisition caused by external interference or a misacquisition caused by the circuit failure of a certain acquisition channel itself, which increases the time and cost of later maintenance and fault analysis and positioning. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a filament current acquisition device for rail transit signal lights, which can monitor the state and manage the health of the filament current, thereby improving the reliability and safety of filament current acquisition.

[0005] The purpose of the present invention is realized as follows: A filament current acquisition device for a rail transit signal machine lamp includes an external signal source, an internal signal source, a current signal acquisition channel, a CPU, and a mutual exclusion relay;

[0006] The external signal source includes an AC voltage source and a signal lamp;

[0007] The internal signal source includes a digital-to-analog conversion circuit and a voltage-current conversion circuit; wherein, the input end of the voltage-current conversion circuit is connected to the output end of the digital-to-analog conversion circuit;

[0008] The current signal acquisition channel is composed of a current sampling resistor, an isolation circuit, a filtering and conditioning circuit, and an analog-to-digital conversion circuit. Among them, one end of the current sampling resistor serves as the positive input end of the current signal acquisition channel and is connected to the positive input end of the isolation circuit, and the other end of the current sampling resistor serves as the negative input end of the current signal acquisition channel and is connected to the negative input end of the isolation circuit. The positive input end of the filtering and conditioning circuit is connected to the positive output end of the isolation circuit, and the negative input end of the filtering and conditioning circuit is connected to the negative output end of the isolation circuit. The positive input end of the analog-to-digital conversion circuit is connected to the positive output end of the filtering and conditioning circuit, and the negative input end of the analog-to-digital conversion circuit is connected to the negative output end of the filtering and conditioning circuit.

[0009] The input end of the CPU is connected to the output end of the analog-to-digital conversion circuit; the output end of the CPU is connected to the input end of the digital-to-analog conversion circuit.

[0010] One end of the first normally open contact of the mutual exclusion relay is connected to the live wire end of the external signal source, and the other end of the first normally open contact is connected to the positive input end of the current signal acquisition channel. One end of the second normally open contact of the mutual exclusion relay K is connected to the neutral wire end of the external signal source, and the other end of the second normally open contact is connected to the negative input end of the current signal acquisition channel.

[0011] One end of the first normally closed contact of the mutual exclusion relay is connected to the positive end of the internal signal source, and the other end of the first normally closed contact is connected to the positive input end of the current signal acquisition channel. One end of the second normally closed contact of the mutual exclusion relay is connected to the neutral wire end of the internal signal source, and the other end of the second normally closed contact is connected to the negative input end of the current signal acquisition channel. One end of the third normally closed contact of the mutual exclusion relay is connected to the positive end of the internal digital power supply, and the other end of the third normally closed contact is connected to the feedback signal input end of the CPU through a current limiting resistor.

[0012] For the above-mentioned filament current acquisition device of the rail transit signal lamp, the current signal acquisition channel may also be composed of a current transformer, a current sampling resistor, a filtering and conditioning circuit, and an analog-to-digital conversion circuit. Among them, the positive input end of the primary coil of the current transformer is the positive input end of the current signal acquisition channel and is respectively connected to one end of the current sampling resistor and the positive input end of the filtering and conditioning circuit. The negative input end of the primary coil of the current transformer is the negative input end of the current signal acquisition channel and is respectively connected to the other end of the current sampling resistor and the negative input end of the filtering and conditioning circuit. The positive input end of the analog-to-digital conversion circuit is connected to the positive output end of the filtering and conditioning circuit, and the negative input end of the analog-to-digital conversion circuit is connected to the negative output end of the filtering and conditioning circuit.

[0013] For the above-mentioned filament current acquisition device of the rail transit signal lamp, the isolation circuit is composed of magnetic isolation and an operational amplifier, or composed of optical isolation and an operational amplifier, or composed of capacitive isolation and an operational amplifier.

[0014] The above-mentioned filament current acquisition device for rail transit signal lights, wherein the filter conditioning circuit is an operational amplifier circuit.

[0015] The filament current acquisition device for rail transit signal lights of the present invention has the following characteristics: It can switch the input signal source of the current signal acquisition channel through a mutually exclusive relay to form a filament current acquisition loop or an internal current acquisition loop, and can respectively detect the quality of the internal current acquisition loop and the filament current acquisition loop, thereby improving the reliability and safety of filament current acquisition. For a driving loop that has not been lit for a long time, it can early warn of the abnormal state of the filament current acquisition loop. For a lit loop in use, in the case of abnormal filament current being acquired, it can switch to the internal current acquisition loop for self-checking, and quickly locate whether the fault source is an external signal source or an internal signal source of this device. Similarly, for a lit loop in use, periodic self-checking can promptly detect the abnormality of the filament current acquisition loop, enabling the system to promptly switch to the safe side to avoid misjudging the state of the electric light. Description of the Drawings

[0016] Figure 1 is a circuit schematic diagram of the filament current acquisition device for rail transit signal lights of the present invention;

[0017] Figure 2 is another circuit schematic diagram of the filament current acquisition device for rail transit signal lights of the present invention. Detailed Embodiments

[0018] The present invention will be further described below in conjunction with the drawings.

[0019] Please refer to Figure 1 and Figure 2 The filament current acquisition device for rail transit signal lights of the present invention includes an external signal source 1, an internal signal source 2, a current signal acquisition channel 3, a CPU, and a mutually exclusive relay K.

[0020] The external signal source 1 includes an AC voltage source 11 for powering the signal machine from outside the board and a signal light 12 for serving as a load.

[0021] The internal signal source 2 includes a voltage-current conversion circuit 21 for converting an analog AC voltage signal into an analog AC current signal and a digital-to-analog conversion circuit 22 for generating an analog AC voltage signal; the input end of the voltage-current conversion circuit 21 is connected to the output end of the digital-to-analog conversion circuit 22.

[0022] The current signal acquisition channel 3 consists of a current sampling resistor Rs for converting the current signal into a voltage signal, an isolation circuit 32 for isolating the strong and weak electrical signals, a filter conditioning circuit 33 for eliminating high-frequency noise signals and scaling the signal ratio, and an analog-to-digital conversion circuit 34 for converting the analog quantity of the current signal into a digital quantity (see Figure 1 ); among them, one end of the current sampling resistor Rs serves as the positive input end of the current signal acquisition channel 3 and is connected to the positive input end of the isolation circuit 32, and the other end of the current sampling resistor Rs serves as the negative input end of the current signal acquisition channel 3 and is connected to the negative input end of the isolation circuit 32; the positive input end of the filter conditioning circuit 33 is connected to the positive output end of the isolation circuit 32, and the negative input end of the filter conditioning circuit 33 is connected to the negative output end of the isolation circuit 32; the positive input end of the analog-to-digital conversion circuit 34 is connected to the positive output end of the filter conditioning circuit 33, and the negative input end of the analog-to-digital conversion circuit 34 is connected to the negative output end of the filter conditioning circuit 33. The isolation circuit 32 is composed of magnetic isolation and an operational amplifier, or composed of optical isolation and an operational amplifier, or composed of capacitive isolation and an operational amplifier; the filter conditioning circuit 33 is an operational amplifier circuit.

[0023] The CPU is used to control the output of the digital-to-analog conversion circuit 34 and the acquisition of the analog-to-digital conversion circuit 22. The control chip of the CPU can be ARM, PowerPC or FPGA; the input end of the CPU is connected to the output end of the analog-to-digital conversion circuit 34, and the output end of the CPU is connected to the input end of the digital-to-analog conversion circuit 22.

[0024] The mutually-exclusive relay K is used to switch the external signal source 1 and the internal signal source 2. One end of the first normally-open contact of the mutually-exclusive relay K is connected to the live wire end of the external signal source 1, and the other end of the first normally-open contact is connected to the positive input end of the current signal acquisition channel 3; one end of the second normally-open contact of the mutually-exclusive relay K is connected to the neutral wire end of the external signal source 1, and the other end of the second normally-open contact is connected to the negative input end of the current signal acquisition channel 3;

[0025] One end of the first normally-closed contact of the mutually-exclusive relay K is connected to the positive end of the internal signal source 2, and the other end of the first normally-closed contact is connected to the positive input end of the current signal acquisition channel 3; one end of the second normally-closed contact of the mutually-exclusive relay K is connected to the neutral wire end of the internal signal source 2, and the other end of the second normally-closed contact is connected to the negative input end of the current signal acquisition channel 3; one end of the third normally-closed contact of the mutually-exclusive relay K is connected to the positive end of the internal digital power supply VCC1, and the other end of the third normally-closed contact is connected to the feedback signal input end of the CPU through a current-limiting resistor R1; the CPU judges the state of the mutually-exclusive relay K through the state of this feedback signal. When this feedback signal is at a high level, it indicates that the normally-open contact of the mutually-exclusive relay K is disconnected and the normally-closed contact is connected; when this feedback signal is at a low level, it indicates that the normally-open contact of the mutually-exclusive relay K is connected and the normally-closed contact is disconnected.

[0026] The CPU can control whether the coil of the mutex relay K is energized to control the connection or disconnection of the normally open and normally closed contacts of the mutex, thereby switching the input signal source of the current signal acquisition channel 3. It is used to control the state of the mutex relay K. When this feedback signal is at a high level, it means that the normally open contact of the mutex relay K is disconnected and the normally closed contact is connected, and the input signal source of the current signal acquisition channel 3 is switched to the internal signal source 2 (internal self-check current source); when this feedback signal is at a low level, the CPU controls the normally open contact of the mutex relay K to connect and the normally closed contact to disconnect, and the input signal source of the current signal acquisition channel 3 is switched to the external signal source 1 (the filament current source of the external signal lamp).

[0027] When the external signal source 1 is switched to the input signal source of the current signal acquisition channel 3 through the mutex relay K, a filament current acquisition loop is formed, and the flow direction of the current signal is as follows:

[0028] AC power supply 11 → signal lamp 12 → mutex relay K (normally open contact closed) → current acquisition resistor Rs → isolation circuit 32 → filter conditioning circuit 33 → analog-to-digital conversion circuit 34 → CPU;

[0029] When the internal signal source 2 is switched to the input signal source of the current signal acquisition channel 3 through the mutex relay K, an internal self-check current acquisition loop is formed, and the flow direction of the current signal is as follows:

[0030] CPU → digital-to-analog conversion circuit 22 → voltage-current conversion circuit 21 → mutex relay K (normally closed contact closed) → current acquisition resistor Rs → isolation circuit 32 → filter conditioning circuit 33 → analog-to-digital conversion circuit 34 → CPU;

[0031] Since the signal lamp is an outdoor device, in order to prevent the outdoor signal from affecting the internal circuit of the system, the isolation circuit 32 is essential. The isolation circuit 32 is generally small in size, and it is suitable for occasions with high requirements for volume. The disadvantage is that the price of the isolation circuit 32 is relatively high. If the requirements for volume are relatively low and the price is relatively sensitive, a current transformer can be used for signal isolation, that is, the current signal acquisition channel 3 is composed of a current transformer CT, a current sampling resistor Rs, a filter conditioning circuit 33 and an analog-to-digital conversion circuit 34 (see Figure 2 ). Among them, the positive input end of the primary coil of the current transformer CT is the positive input end of the current signal acquisition channel 3 and is respectively connected to one end of the current sampling resistor Rs and the positive input end of the filter conditioning circuit 33. The negative input end of the primary coil of the current transformer CT is the negative input end of the current signal acquisition channel 3 and is respectively connected to the other end of the current sampling resistor Rs and the negative input end of the filter conditioning circuit 33; the positive input end of the analog-to-digital conversion circuit 34 is connected to the positive output end of the filter conditioning circuit 33, and the negative input end of the analog-to-digital conversion circuit 34 is connected to the negative output end of the filter conditioning circuit 33.

[0032] When the external signal source 1 is switched to the input signal source of the current signal acquisition channel 3 through the mutual exclusion relay K, a filament current acquisition circuit is formed, and the flow direction of the current signal is as follows:

[0033] AC power supply 11 → signal lamp 12 → mutual exclusion relay K (normally open contact is closed) → current transformer CT → current acquisition resistor Rs → filter conditioning circuit 33 → analog-to-digital conversion circuit 34 → CPU;

[0034] When the internal signal source 2 is switched to the input signal source of the current signal acquisition channel 3 through the mutual exclusion relay K, an internal self-check current acquisition circuit is formed, and the flow direction of the current signal is as follows:

[0035] CPU → digital-to-analog conversion circuit 22 → voltage-current conversion circuit 21 → mutual exclusion relay K (normally closed contact is closed) → current transformer CT → current acquisition resistor R s → filter conditioning circuit 33 → analog-to-digital conversion circuit 34 → CPU.

[0036] In the filament current acquisition device of the rail transit signal lamp of the present invention, the CPU can periodically switch the input signal source of the current signal acquisition channel according to the system requirements, and detect the quality of the internal self-check current acquisition circuit and the filament current acquisition circuit through the input signal source. The internal signal source 2 is based on a set of fixed data written by the CPU to the digital-to-analog conversion circuit 22. The digital-to-analog conversion circuit 22 converts it into a set of fixed voltage output values, and then the voltage-current conversion circuit 21 converts it into a set of fixed current input values to be provided to the current signal acquisition channel 3 for acquisition (the output of the voltage-current conversion circuit 21 is only related to the output of the digital-to-analog conversion circuit 22, that is, I out =V DAC / G ain , and G ain is constant when the load does not exceed the design value). When the input signal source of the current signal acquisition channel 3 is the internal signal source 2, since the input signal source is fixed for the current signal acquisition channel 3, the acquisition value of the internal current acquisition circuit is also fixed. Therefore, the CPU will compare the actual read-back value of the analog-to-digital conversion circuit 34 with the preset read-back value of the analog-to-digital conversion circuit 34 in the CPU. When the actual read-back value is consistent with the preset read-back value, it indicates that the internal current acquisition circuit is normal; when the difference between the actual read-back value and the preset read-back value exceeds the error specified by the system, it can be judged that there is a fault point in the internal self-check current acquisition circuit; the CPU can timely upload the self-check information to the upper maintenance station and make corresponding processing, which can play a role in early warning or fault location, thereby improving the reliability and safety of the filament current acquisition of the signal lamp.

[0037] For the driving circuit that has not been lit for a long time, the abnormal state of the filament current acquisition circuit can be warned in advance. For the lit circuit in use, in the case of abnormal filament current being acquired, it can be switched to the internal self-check current acquisition circuit for self-check, and the fault source can be located in time as whether it is an external signal source or an internal signal source. Similarly, for the lit circuit in use, periodic self-check can timely detect the abnormality of the filament current acquisition circuit, enabling the system to be timely directed to the safe side to avoid misjudging the state of the electric lamp.

[0038] The filament current acquisition device of the rail transit signal lamp of the present invention can also redundantly set up the current signal acquisition channels 3. Both of the two current signal acquisition channels 3 are composed of a current sampling resistor Rs, an isolation circuit, a filtering and conditioning circuit, and an analog-to-digital conversion circuit; or both of the two current signal acquisition channels 3 are composed of a current transformer CT, a current sampling resistor Rs, a filtering and conditioning circuit, and an analog-to-digital conversion circuit; or one current signal acquisition channel 3 is composed of a current sampling resistor Rs, an isolation circuit, a filtering and conditioning circuit, and an analog-to-digital conversion circuit, and the other current signal acquisition channel 3 is composed of a current transformer CT, a current sampling resistor Rs, a filtering and conditioning circuit, and an analog-to-digital conversion circuit.

[0039] The above embodiments are only for illustrating the present invention, rather than limiting the present invention. Those skilled in the relevant technical fields can also make various transformations or modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also fall within the scope of the present invention, which should be defined by each claim.

Claims

1. A filament current acquisition device for a rail transit signal lamp, comprising an external signal source, an internal signal source, a current signal acquisition channel, a CPU and a mutually exclusive relay; characterized in that: The external signal source includes an AC voltage source and a signal lamp; The internal signal source includes a digital-to-analog conversion circuit and a voltage-to-current conversion circuit; wherein the input end of the voltage-to-current conversion circuit is connected to the output end of the digital-to-analog conversion circuit; The current signal acquisition channel is composed of a current sampling resistor, an isolation circuit, a filter conditioning circuit and an analog-to-digital conversion circuit; wherein one end of the current sampling resistor is used as the input positive end of the current signal acquisition channel and is connected to the input positive end of the isolation circuit, and the other end of the current sampling resistor is used as the input negative end of the current signal acquisition channel and is connected to the input negative end of the isolation circuit; the input positive end of the filter conditioning circuit is connected to the output positive end of the isolation circuit, and the input negative end of the filter conditioning circuit is connected to the output negative end of the isolation circuit; the input positive end of the analog-to-digital conversion circuit is connected to the output positive end of the filter conditioning circuit, and the input negative end of the analog-to-digital conversion circuit is connected to the output negative end of the filter conditioning circuit; The input end of the CPU is connected to the output end of the analog-to-digital conversion circuit; the output end of the CPU is connected to the input end of the digital-to-analog conversion circuit; One end of the first normally open contact of the mutually exclusive relay is connected to the live wire end of the external signal source, and the other end of the first normally open contact is connected to the input positive end of the current signal acquisition channel; one end of the second normally open contact of the mutually exclusive relay K is connected to the neutral wire end of the external signal source, and the other end of the second normally open contact is connected to the input negative end of the current signal acquisition channel; One end of the first normally closed contact of the mutually exclusive relay is connected to the positive end of the internal signal source, and the other end of the first normally closed contact is connected to the positive input end of the current signal acquisition channel; one end of the second normally closed contact of the mutually exclusive relay is connected to the neutral line end of the internal signal source, and the other end of the second normally closed contact is connected to the negative input end of the current signal acquisition channel; one end of the third normally closed contact of the mutually exclusive relay is connected to the positive end of the internal digital power supply, and the other end of the third normally closed contact is connected to the feedback signal input end of the CPU through a current limiting resistor.

2. The filament current acquisition device for a rail transit signal lamp according to claim 1, characterized in that: The current signal acquisition channel is composed of a current transformer, a current sampling resistor, a filter conditioning circuit and an analog-to-digital conversion circuit, wherein the input positive end of the primary coil of the current transformer is the input positive end of the current signal acquisition channel and is respectively connected to one end of the current sampling resistor and the input positive end of the filter conditioning circuit, the input negative end of the primary coil of the current transformer is the input negative end of the current signal acquisition channel and is respectively connected to the other end of the current sampling resistor and the input negative end of the filter conditioning circuit; the input positive end of the analog-to-digital conversion circuit is connected to the output positive end of the filter conditioning circuit, and the input negative end of the analog-to-digital conversion circuit is connected to the output negative end of the filter conditioning circuit.

3. The filament current acquisition device for a rail transit signal lamp according to claim 1, characterized in that: The isolation circuit is composed of magnetic isolation and an operational amplifier, or optical isolation and an operational amplifier, or capacitive isolation and an operational amplifier.

4. The filament current acquisition device for a rail transit signal lamp according to claim 1, characterized in that: The filtering and conditioning circuit is an operational amplifier circuit.

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