Subway train wet current trigger circuit
By adopting a combination design of capacitor, optocoupler, NPN transistor, voltage divider and current limiting resistor in the digital quantity acquisition circuit of subway trains, the problem of small and unstable wet current is solved, and the wetness with high precision and low power consumption is achieved Current supply meets the wet current needs of subway trains.
Patent Information
- Application Number
- CN202411108079.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-13
- Publication Date
- 2024-12-20
AI Technical Summary
The wet current design in the digital acquisition circuit of subway trains has problems such as large power consumption, unstable wet current and inability to meet the constant wet current requirements. The prior art is difficult to provide sufficient wet current without increasing single-channel power consumption.
Wet current trigger circuit including capacitors, optocouplers, NPN transistors, voltage dividers, controllable precision voltage stabilization sources and current limiting resistors are adopted to provide initial wet current through capacitors, optocouplers realize signal isolation, NPN transistors adjust current, and current limiting Resistors control current to ensure constant wet current is provided at high accuracy and low power consumption.
It effectively solves the problems of small, unstable and large power consumption in digital acquisition circuits, and provides high-precision and controllable wet current within the user's required time, reducing the power consumption and heating of the overall circuit.
Smart Images
Figure CN119171891A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of trigger circuits, and in particular to a wet current trigger circuit for a subway train. Background Art
[0002] Subway trains have a large number of mechanical relays as digital control signal generation sources. Mechanical relays generally require the contacts to maintain a certain current when open to prevent premature oxidation of the mechanical contacts. This current is called wet current in the industry and is generally greater than 5mA. Considering the power consumption of digital acquisition circuits, the commonly used digital quantity acquisition circuits generally have an acquisition current design of about 1mA, which cannot provide sufficient wet current. If the digital quantity acquisition circuit is designed to have an acquisition current of more than 5mA, the power consumption of a single channel will increase dramatically and cannot meet the heat dissipation requirements. At the same time, when the voltage of the current wet current circuit changes, the wet current will also change, which cannot meet the requirements of constant wet current.
[0003] The existing technical solutions generally use a resistive load as a current channel for the wetting current. The circuit is relatively simple, and the external input voltage directly flows to the negative terminal through the resistor to generate the wetting current.
[0004] Digital quantity acquisition circuits are widely used in subway trains. Taking the remote input and output unit as an example, there can be up to 32 digital quantity acquisition channels on a single 3U board. If each channel is equipped with a wet current trigger circuit, the input current of the entire board may be as high as 160mA or more. At the DC110V or DC24V voltage level, the power consumption and heat generation are unbearable. At the same time, the current wet current circuit will change with the change of voltage, which cannot meet the requirement of constant wet current. Summary of the invention
[0005] According to the technical problems mentioned in the above background technology, a subway train wet current trigger circuit is provided.
[0006] The technical means adopted by the present invention are as follows:
[0007] Subway train wet current trigger circuit, including: capacitor, optocoupler, NPN transistor, voltage divider resistor, controllable precision voltage source and current limiting resistor;
[0008] The capacitor is used for input filtering and providing initial wet current; the optocoupler is used for photoelectric isolation of control signals and external signals; the NPN transistor is used for current setting and current bearing of the wet current circuit. When the circuit is turned on, the main wet current generated flows through the transistor; the controllable precision voltage regulator can output a precise reference power supply, and when a positive power supply is added, a high-precision reference voltage can be output; the voltage divider resistor is used to bear the excess voltage at both ends of the controllable precision voltage regulator; the current limiting resistor is used to control the circuit current;
[0009] When a high level is input to the input terminal IN, the capacitor provides an instantaneous wetting current; when a constant wetting current is provided at the input terminal IN, the circuit is actively triggered through IN_CTR to form a high-precision and controllable wetting current.
[0010] Furthermore, when the input voltage at the input terminal IN is at a low level, the entire wet current trigger circuit does not work;
[0011] When the input voltage at the input terminal IN is at a high level, the capacitor provides an instantaneous wetting current before being fully charged, and the capacitor performs filtering; at the same time, IN_CTR is set to 0V, the wetting current control circuit is turned on, and the required high-precision wetting current is generated;
[0012] When the trigger meets a certain time, IN_CTR is given 3.3V and the wet current control circuit is disconnected.
[0013] Furthermore, the capacitor is a filter capacitor, which provides an initial wetting current. When the capacitor is fully charged, the wetting current provided by the capacitor ends.
[0014] Furthermore, the voltage across the current-limiting resistor is the reference voltage generated by the controllable precision voltage-stabilizing source, and the current of the current-limiting resistor is the wetting current of the circuit.
[0015] Furthermore, in the controllable precision voltage-stabilizing source, when positive power is applied to pin 2 and pin 1, pin 3 outputs a high-precision reference voltage.
[0016] Furthermore, the NPN transistor operates in a signal amplification region.
[0017] Compared with the prior art, the present invention has the following advantages:
[0018] The circuit of the present invention effectively solves the problems of small wet current, unstable wet current and large acquisition power consumption of the digital quantity acquisition circuit in subway trains.
[0019] The circuit of the present invention can generate a wetting current for a certain period of time according to the actual needs of the user, thereby solving the problems of small wetting current, unstable wetting current and large collection power consumption in the digital quantity acquisition circuit. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.
[0021] Figure 1 The invention provides a digital quantity acquisition circuit. DETAILED DESCRIPTION
[0022] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.
[0023] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.
[0024] like Figure 1 As shown, the present invention provides a subway train wet current trigger circuit, including: a capacitor, an optical coupler, an NPN transistor, a voltage divider resistor, a controllable precision voltage source and a current limiting resistor;
[0025] The capacitor is used for input filtering and providing initial wet current; the optocoupler is used for photoelectric isolation of control signals and external signals; the NPN transistor works in the signal amplification area and is used for current setting and current bearing of the wet current circuit. When the circuit is turned on, the main wet current generated flows through the transistor; the controllable precision voltage regulator can output a precise reference power supply, and when a positive power supply is added, a high-precision reference voltage can be output; the voltage divider resistor is used to bear the excess voltage at both ends of the controllable precision voltage regulator; the current limiting resistor is used to control the circuit current;
[0026] When a high level is input to the input terminal IN, the capacitor provides an instantaneous wetting current; when a constant wetting current is provided at the input terminal IN, the circuit is actively triggered through IN_CTR to form a high-precision and controllable wetting current.
[0027] As a preferred embodiment, in the present application, when the input voltage at the input terminal IN is at a low level, the entire wet current trigger circuit does not work; when the input voltage at the input terminal IN is at a high level, the capacitor provides an instantaneous wet current before being fully charged, and is filtered by the capacitor; at the same time, IN_CTR gives 0V, the wet current control circuit is turned on, and the required high-precision wet current is generated; when the trigger meets a certain time, IN_CTR gives 3.3V, and the wet current control circuit is disconnected.
[0028] Preferably, the capacitor is a filter capacitor, which provides an initial wetting current. When the capacitor is fully charged, the wetting current provided by the capacitor ends.
[0029] As a preferred implementation, in the present application, the voltage across the current limiting resistor is the reference voltage generated by the controllable precision voltage stabilizing source, and the current of the current limiting resistor is the wet current of the circuit.
[0030] As a preferred implementation, in the present application, in the controllable precision voltage stabilizing source, when positive power is applied to pin 2 and pin 1, pin 3 outputs a high-precision reference voltage.
[0031] Example:
[0032] As an implementation mode, in the present application, the external digital signal is set to a DC24V voltage level, and the wet current requirement is not less than 10mA.
[0033] The external digital voltage input terminal IN is set to DC24V for high level and 0V for low level, and 24V_GND is the ground of the external digital voltage.
[0034] The filter capacitor C1 is set to 0.1uf and provides an initial wetting current. When the capacitor is fully charged, the wetting current provided by the capacitor ends.
[0035] The current limiting resistor R3 is set to 250 ohms. The voltage across the resistor is the reference voltage 2.5V generated by D3, that is, the wet current of this circuit is 2.5V / 250R=10mA.
[0036] A controllable precision voltage regulator D1, model TL431, is set to output a precise reference power supply. When a positive power supply is applied to pin 2 and pin 1, pin 3 can output a high-precision reference voltage.
[0037] An NPN transistor Q1, model 2N3904, is set to work in the amplification area and is used for current setting and current bearing of the wet current circuit. When the circuit is turned on, the main wet current generated flows through Q1.
[0038] The voltage divider resistor R2 is set to 10K ohms to bear the excess voltage across D1.
[0039] Set up the optocoupler U1, model TLP183, to optically isolate the input side from the output side.
[0040] The current limiting resistor R1 is set to 1k ohm to limit the input current of the optocoupler.
[0041] Set the control terminal IN_CTR for wet current triggering. When IN_CTR is set to DC3.3V, the wet current control circuit is invalid. When IN_CTR is set to 0V, the wet current control circuit is valid.
[0042] As a preferred implementation, the specific working logic of this circuit is:
[0043] When the IN input voltage is 0V, the digital quantity acquisition circuit is not conducting, and the OUT terminal outputs 0V, that is, the digital quantity acquisition result is 0. IN_CTR is given 3.3V, and the wet current control circuit is not conducting.
[0044] When the IN input voltage is DC24V, the digital quantity acquisition circuit is turned on, the on-current of the acquisition circuit is less than 1mA, and the OUT terminal outputs 3.3V, that is, the digital quantity acquisition result is 1. At this time, IN_CTR gives 0V, the wet current control circuit is turned on, and the required high-precision wet current is generated. When the current output meets the requirements for a certain period of time, IN_CTR gives 3.3V, and the wet current control circuit is disconnected.
[0045] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages and disadvantages of the embodiments. In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments. In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways.
[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. Subway train wet current trigger circuit, characterized in that: include: Capacitors, optocouplers, NPN transistors, voltage divider resistors, controllable precision voltage regulators and current limiting resistors; The capacitor is used for input filtering and providing initial wetting current; The optical coupler is used for photoelectric isolation of control signals and external signals; the NPN transistor is used for current setting and current bearing of the wet current circuit. When the circuit is turned on, the main wet current generated flows through the transistor; the controllable precision voltage regulator can output a precise reference power supply, and when a positive power supply is added, a high-precision reference voltage can be output; the voltage divider resistor is used to bear the excess voltage at both ends of the controllable precision voltage regulator; the current limiting resistor is used to control the circuit current; When a high level is input to the input terminal IN, the capacitor provides an instantaneous wetting current; when a constant wetting current is provided at the input terminal IN, the circuit is actively triggered through IN_CTR to form a high-precision and controllable wetting current.
2. The subway train wet current trigger circuit according to claim 1, characterized in that: When the input voltage at the input terminal IN is at a low level, the entire wet current trigger circuit does not work; When the input voltage at the input terminal IN is at a high level, the capacitor provides an instantaneous wetting current before being fully charged, and the capacitor performs filtering; at the same time, IN_CTR is set to 0V, the wetting current control circuit is turned on, and the required high-precision wetting current is generated; When the trigger meets a certain time, IN_CTR is given 3.3V and the wet current control circuit is disconnected.
3. The subway train wet current trigger circuit according to claim 1, characterized in that: The capacitor is a filter capacitor, which provides an initial wetting current. When the capacitor is fully charged, the wetting current provided by the capacitor ends.
4. The subway train wet current trigger circuit according to claim 1, characterized in that: The voltage across the current-limiting resistor is the reference voltage generated by the controllable precision voltage-stabilizing source, and the current of the current-limiting resistor is the wet current of the circuit.
5. The subway train wet current trigger circuit according to claim 1, characterized in that: In the controllable precision voltage stabilizing source, when positive power is applied to pin 2 and pin 1, pin 3 outputs a high-precision reference voltage.
6. The subway train wet current trigger circuit according to claim 1, characterized in that: The NPN transistor works in the signal amplification area.