Power supply input self-recovery overvoltage and undervoltage protection system based on rail transit equipment

Abstract

The utility model provides a power supply input self-recovery overvoltage and undervoltage protection system based on rail transit equipment, which belongs to the technical field of electronic circuits and comprises a filter circuit, a sampling power supply circuit, a sampling and processing circuit and an MOS (metal oxide semiconductor) switching circuit. The sampling power supply circuit is used for reducing an input voltage and then supplying power to the sampling and processing circuit, and the sampling and processing circuit is used for collecting a rail transit direct current signal, generating a control signal and transmitting the control signal to the MOS switching circuit; and the MOS switching circuit receives the control signal generated by the sampling and processing circuit to control the on-off of the high-power power supply. A triode fractional step-down circuit and a comparator comparison input voltage circuit are adopted, and the problems of electricity taking heating in a rail transit VDC110V input self-recovery overvoltage and undervoltage protection circuit and critical jitter and large critical input voltage range in overvoltage and undervoltage protection are solved. The problems of heating of an overvoltage protection power supply and jitter of critical voltage are solved, and the cost and the stability and safety of the circuit are reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of electronic circuits, and particularly relates to a self - recovery over - and - under - voltage protection system for the power supply input of rail transit equipment. Background Technique

[0002] The self - recovery over - and - under - voltage protection system for the power supply input of rail transit equipment is an important safety protection measure. It can automatically disconnect the power supply when the voltage is abnormal to avoid equipment damage, and automatically resume power supply after the voltage returns to normal.

[0003] It is analyzed that the traditional rail transit DC110V voltage fluctuation is likely to cause damage to rail transit control equipment. The existing self - recovery over - and - under - voltage protection circuit has the characteristics of unstable power heating in over - voltage power supply, large critical voltage range and critical jitter in under - voltage protection and over - voltage protection. Content of the Utility Model

[0004] The purpose of the utility model is to provide a self - recovery over - and - under - voltage protection system for the power supply input of rail transit equipment. The utility model aims to solve the problems of over - voltage protection power heating and critical voltage jitter.

[0005] To achieve the above - mentioned purpose, the utility model provides the following technical solutions:

[0006] A self - recovery over - and - under - voltage protection system for the power supply input of rail transit equipment includes: a filtering circuit, a sampling power supply circuit, a sampling and processing circuit, and a MOS switch circuit; the sampling power supply circuit supplies power to the sampling and processing circuit after stepping down the input voltage, the sampling and processing circuit collects rail transit DC signals and generates control signals to be transmitted to the MOS switch circuit, and the MOS switch circuit receives the control signals generated by the sampling and processing circuit to control the on - off of the high - power power supply switch.

[0007] As a preferred scheme of the utility model, the sampling power supply circuit steps down the input voltage in the way of double - triode distributed voltage reduction, and the sampling power supply circuit consists of a primary voltage - reduction circuit, a secondary voltage - reduction circuit, a linear DC voltage - stabilizing power supply U1, a filtering capacitor C1, and a filtering capacitor C2.

[0008] As a preferred scheme of the utility model, the primary voltage - reduction circuit consists of a triode Q1, a resistor R4, and a zener diode D1. The input voltage is electrically connected to the base of the triode Q1 through the resistor R1, the input voltage is also electrically connected to the collector of the triode Q1, and the negative electrode of the zener diode D1 is electrically connected to the base of the triode Q1.

[0009] As a preferred solution of the present utility model, the secondary step-down circuit is composed of a triode Q2, a resistor R1 and a zener diode D2. The emitter of the triode Q2 is electrically connected to the input end of the linear DC regulated power supply U1. The resistor R1 is electrically connected between the emitter of the triode Q1 and the base of the triode Q2. The emitter of the triode Q1 is also electrically connected to the collector of the triode Q2.

[0010] As a preferred solution of the present utility model, the sampling and processing circuit is divided into a sampling circuit and a processing circuit. The sampling circuit is divided into an undervoltage sampling circuit and an overvoltage sampling circuit. The undervoltage sampling circuit is connected to the positive pole of the input voltage by sequentially connecting resistors R23, R16, R10, R5, and R2 in series. After the resistors R23, R16, and R10 are sequentially connected in series, they are respectively connected in parallel with capacitors C6 and C4. The connection end of the resistors R10 and R5 is connected in series with a resistor R8 and used as the output end of the undervoltage sampling circuit. The overvoltage sampling circuit is connected to the positive pole of the input voltage by sequentially connecting resistors R24, R17, R11, R6, and R3 in series. After the resistors R24, R17, and R11 are sequentially connected in series, they are respectively connected in parallel with capacitors C5 and C8. The connection end of the resistors R11 and R6 is connected in series with a resistor R9 and used as the output end of the undervoltage sampling circuit.

[0011] As a preferred solution of the present utility model, the processing circuit includes an overvoltage reference voltage circuit, an undervoltage reference voltage circuit, and a signal comparator U2. The overvoltage reference voltage circuit is respectively electrically connected to the input a+ and gnd pins of the signal comparator U2. The undervoltage reference voltage circuit is respectively electrically connected to the input b+ and gnd of the signal comparator U2.

[0012] As a preferred solution of the present utility model, the overvoltage reference voltage circuit includes resistors R15, R19, R20, and capacitor C11. The resistor R20 is connected in parallel with the capacitor C11 and then connected in series with the resistor R15 to the positive pole of the sampling power supply circuit. The connection end of the resistors R15 and R20 is connected to the input a- of the signal comparator U2 through a series resistor R19. The undervoltage reference voltage circuit includes resistors R14, R21, R22, and capacitor C10. The resistor R22 is connected in parallel with the capacitor C10 and then connected in series with the resistor R14 to the positive pole of the sampling power supply circuit. The connection end of the resistors R14 and R22 is connected to the input b- of the signal comparator U2 through a series resistor R21.

[0013] As a preferred embodiment of the present utility model, the MOS switch circuit includes a resistor R7, a capacitor C3, a zener diode D3, a MOS transistor Q3, an NPN transistor Q4, a resistor R18, and a capacitor C9. The resistor R7 and the capacitor C3 form an under-voltage protection switch input RC filter circuit. The under-voltage protection switch input RC filter circuit is electrically connected to the G pole of the MOS transistor Q3 through the zener diode D3. The resistor R18 and the capacitor C9 form an over-voltage protection switch input filter circuit. The over-voltage protection switch input filter circuit is electrically connected to the base of the NPN transistor Q4.

[0014] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0015] 1. This design uses a transistor fractional step-down circuit to step down the input voltage DC110V, solving the problems of overheating in wide-voltage DC step-down and stable output voltage. The design of using multiple series-mounted chip resistors for voltage division increases the heat dissipation capacity. When the DC voltage is 200V, the temperature does not exceed 80°C. Compared with other heating methods, the present invention has less energy loss, higher efficiency, and more uniform temperature rise.

[0016] 2. This design adopts a self-recovery over- and under-voltage technology to monitor the input voltage information in real time and determine whether to cut off the input power supply based on the voltage information, thereby further ensuring the safety of the power supply and the load. At the same time, self-recovery over- and under-voltage protection can be achieved with only a very small number of components, resulting in good stability, high control voltage, simple control, low cost, and easy implementation of the self-recovery over- and under-voltage protection. Description of the Drawings

[0017] The drawings are used to provide a further understanding of the present utility model and constitute a part of the specification. They are used together with the embodiments of the present utility model to explain the present utility model and do not constitute a limitation to the present utility model. In the drawings:

[0018] Figure 1 is the module architecture diagram of the self-recovery over- and under-voltage protection system for the power supply input of rail transit equipment according to the present utility model;

[0019] Figure 2 is the sampling power supply circuit diagram of the self-recovery over- and under-voltage protection system for the power supply input of rail transit equipment according to the present utility model;

[0020] Figure 3 is the sampling circuit diagram of the self-recovery over- and under-voltage protection system for the power supply input of rail transit equipment according to the present utility model;

[0021] Figure 4 is the processing circuit diagram of the self-recovery over- and under-voltage protection system for the power supply input of rail transit equipment according to the present utility model;

[0022] Figure 5This is the MOS switch circuit diagram of the self - restoring over - and - under - voltage protection system for the power supply input of rail transit equipment of the present utility model;

[0023] Figure 6 It is the processing flow chart of the self - restoring over - and - under - voltage protection system for the power supply input of rail transit equipment. Specific embodiments

[0024] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0025] Embodiment

[0026] Please refer to Figures 1-5 , the present utility model provides the following technical solutions:

[0027] Based on the self - restoring over - and - under - voltage protection system for the power supply input of rail transit equipment, it includes a filtering circuit, a sampling power supply circuit, a sampling and processing circuit, and a MOS switch circuit; the sampling power supply circuit supplies power to the sampling and processing circuit after stepping down the input voltage, the sampling and processing circuit collects the rail transit DC signal and generates a control signal to be transmitted to the MOS switch circuit, and the MOS switch circuit receives the control signal generated by the sampling and processing circuit to control the on - off of the high - power power supply.

[0028] Specifically, as Figure 1 shown, the sampling and processing circuit includes a sampling circuit and a processing circuit. The sampling circuit converts the DC110V (the normal fluctuation range of the rail transit DC signal is 77V - 137.5V) DC high - voltage signal into an over - and - under - voltage signal, and the processing circuit compares the over - and - under - voltage signal with a reference voltage signal and generates a control signal. The control signal controls the on - off of the high - power power supply through the MOS switch circuit.

[0029] Specifically, as Figure 2As shown in the figure, the sampling power supply circuit uses a dual-triode distributed buck method to step down the input voltage DC110V. However, due to the low stability of the distributed buck, a linear DC voltage regulator U1 is added after the distributed buck. The sampling power supply circuit consists of a first-stage buck circuit, a second-stage buck circuit, a linear DC voltage regulator U1, a filter capacitor C1, and a filter capacitor C2. The first-stage buck circuit is composed of a triode Q1, a resistor R4, and a zener diode D1. The second-stage buck circuit is also composed of a triode Q1, a resistor R4, and a zener diode D1. Capacitors C1 and C2 are filter capacitors, and U1 is a DC linear voltage regulator. The distributed buck circuit solves the heating problem caused by the excessive voltage difference between the sampling circuit voltage and the input voltage. Adding a linear DC voltage regulator U1 after the distributed buck circuit solves the problem of voltage regulation fluctuations generated by the distributed buck circuit.

[0030] As Figure 3 shown, taking the undervoltage sampling circuit as an example, the undervoltage sampling circuit uses a SMT 1210 package and is designed with voltage division by sequentially connecting resistors R23, R16, R10, R5, and R2 in series to increase the heat dissipation capacity, and its temperature does not exceed 80°C. Resistor R8 in the undervoltage sampling circuit is a current-limiting protection resistor, and capacitors C6 and C4 are filter capacitors. This design not only saves PCB layout space but also solves the problem of voltage division and heat dissipation. At DC 200V, the sampling circuit converts the DC high-voltage signal of DC110V (the normal fluctuation range of the DC signal in rail transit is 77V - 137.5V) into an over / undervoltage signal. The processing circuit compares the over / undervoltage signal with a reference voltage signal and generates a control signal. The control signal controls the on / off of the high-power switch power supply through a MOS switch circuit. The circuit structure of the overvoltage sampling circuit is the same as that of the undervoltage sampling circuit.

[0031] As Figure 4 shown, the processing circuit uses an LM193 comparator to compare the sampling voltage with the reference voltage and control the output. Among them, resistors R15, R19, R20, and capacitor C11 form an overvoltage reference voltage circuit, resistors R14, R21, R22, and capacitor C10 form an undervoltage reference voltage circuit, and resistors R12 and R13 are used to improve the driving ability of the output.

[0032] As Figure 5As shown, in the MOS switch circuit, the resistor R7 and the capacitor C3 form an undervoltage protection switch input RC filter circuit. The diode D3 is a zener diode, and its function is to prevent jitter in the undervoltage critical state. When undervoltage occurs, the switch input is in the low-level state, and the MOS transistor Q3 is in the off state. When the voltage exceeds the undervoltage, the MOS transistor Q3 is in the on state. The resistor R18 and the capacitor C9 form an overvoltage protection switch input filter circuit. The triode Q4 is an NPN triode. When overvoltage occurs, the triode Q4 is in the on state, thereby turning off the MOS transistor Q3.

[0033] In specific applications, when the input voltage is filtered by the filter circuit and then input into the sampling and processing circuit for voltage sampling, the processing circuit uses the LM193 comparator to determine whether there is undervoltage. When the input voltage is undervoltage, the system turns off the MOS switch circuit. When the input voltage is not undervoltage, the system turns on the MOS switch circuit. When the processing circuit uses the LM193 comparator to determine whether there is overvoltage, if the input voltage is overvoltage, the MOS switch circuit is turned off. If the input voltage is not overvoltage, the MOS switch circuit is turned on.

[0034] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Based on the self-recovery over-voltage and under-voltage protection system for the power input of rail transit equipment, it is characterized by: include: Filter circuit, sampling power supply circuit, sampling and processing circuit, MOS switch circuit; The sampling power supply circuit supplies power to the sampling and processing circuit by stepping down the input voltage. The sampling and processing circuit collects the rail transit DC signal and generates a control signal to transmit to the MOS switch circuit. The MOS switch circuit receives the control signal generated by the sampling and processing circuit to control the on and off of the switch high-power power supply. The sampling power supply circuit uses a dual triode distributed step-down method to step down the input voltage. The sampling power supply circuit is composed of a primary step-down circuit, a secondary step-down circuit, a linear DC regulated power supply U1, a filter capacitor C1, and a filter capacitor C2; The first-stage step-down circuit is composed of a transistor Q1, a resistor R4 and a voltage-stabilizing diode D1. The input voltage is electrically connected to the base of the transistor Q1 through the resistor R1. The input voltage is also electrically connected to the collector of the transistor Q1. The cathode of the voltage-stabilizing diode D1 is electrically connected to the base of the transistor Q1. The secondary step-down circuit is composed of a transistor Q2, a resistor R1 and a voltage regulator diode D2. The emitter of the transistor Q2 is electrically connected to the input end of the linear DC voltage regulator U1. The resistor R1 is electrically connected between the emitter of the transistor Q1 and the base of the transistor Q2. The emitter of the transistor Q1 is also electrically connected to the collector of the transistor Q2. The sampling and processing circuit is divided into a sampling circuit and a processing circuit. The sampling circuit is divided into an undervoltage sampling circuit and an overvoltage sampling circuit. The undervoltage sampling circuit is connected to the positive electrode of the input voltage by connecting resistors R23, R16, R10, R5 and R2 in series in sequence. The resistors R23, R16 and R10 are connected in series in sequence and are connected in parallel with capacitors C6 and C4 respectively. The resistors R10 and R5 are connected in series with resistor R8 as the output end of the undervoltage sampling circuit. The overvoltage sampling circuit is connected to the positive electrode of the input voltage by connecting resistors R24, R17, R11, R6 and R3 in series in sequence. The resistors R24, R17 and R11 are connected in series in sequence and are connected in parallel with capacitors C5 and C8 respectively. The resistors R11 and R6 are connected in series with resistor R9 as the output end of the undervoltage sampling circuit. The processing circuit includes an overvoltage reference voltage circuit, an undervoltage reference voltage circuit, and a signal comparator U2, wherein the overvoltage reference voltage circuit is electrically connected to the pins input a+ and gnd of the signal comparator U2, respectively, and the undervoltage reference voltage circuit is electrically connected to the pins input b+ and gnd of the signal comparator U2, respectively; The overvoltage reference voltage circuit includes a resistor R15, a resistor R19, a resistor R20, and a capacitor C11. After the resistor R20 is connected in parallel with the capacitor C11, the series resistor R15 is connected to the positive electrode of the sampling power supply circuit. The connection end of the resistor R15 and the resistor R20 is electrically connected to the input a- of the signal comparator U2 through the series resistor R19. The undervoltage reference voltage circuit includes a resistor R14, a resistor R21, a resistor R22, and a capacitor C10. After the resistor R22 is connected in parallel with the capacitor C10, the series resistor R14 is connected to the positive electrode of the sampling power supply circuit. The connection end of the resistor R14 and the resistor R22 is electrically connected to the input b- of the signal comparator U2 through the series resistor R21.

2. The self-recovery over-voltage and under-voltage protection system based on the power input of rail transit equipment according to claim 1 is characterized in that: The MOS switch circuit includes a resistor R7, a capacitor C3, a voltage stabilizing diode D3, a MOS tube Q3, an NPN transistor Q4, a resistor R18, and a capacitor C9. The resistor R7 and the capacitor C3 constitute an undervoltage protection switch input RC filter circuit. The undervoltage protection switch input RC filter circuit is electrically connected to the G pole of the MOS tube Q3 through the voltage stabilizing diode D3. The resistor R18 and the capacitor C9 constitute an overvoltage protection switch input filter circuit. The overvoltage protection switch input filter circuit is electrically connected to the base of the NPN transistor Q4.

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