CN218997679U

CN218997679U - MEC direct current power supply input protection circuit and MEC

Info

Publication number: CN218997679U
Application number: CN202320004845.2U
Authority: CN
Inventors: 魏靖伟
Original assignee: Zhidao Network Technology Beijing Co Ltd
Current assignee: Zhidao Network Technology Beijing Co Ltd
Priority date: 2023-01-03
Filing date: 2023-01-03
Publication date: 2023-05-09
Anticipated expiration: 2033-01-03

Abstract

The application discloses protection circuit and MEC of MEC direct current power supply input, wherein protection circuit includes: the anti-lightning surge circuit, the anti-reverse connection protection circuit, the pulse group filter circuit and the underovervoltage protection circuit are connected in series, and direct current power is input to the anti-lightning surge circuit and is supplied to the MEC after passing through the anti-reverse connection protection circuit, the pulse group filter circuit and the underovervoltage protection circuit. Through the protection circuit in this application, can make the MEC that is used for the roadside can deal with the unstable or unusual condition of power supply input that multiple possible factor led to in the process of construction debugging or long-term outdoor environment operation.

Description

MEC direct current power supply input protection circuit and MEC

Technical Field

The application relates to the technical field of road side MECs, in particular to a protection circuit for MEC direct current power supply input and an MEC.

Background

Multi-access mobile edge computing (english full Multi-access Edge Computing, MEC for short). In the C-V2X vehicle road cloud integrated system, road side MECs are an indispensable part, and power supply of the road side MECs currently has two schemes of POE and DC direct current power supply, and the road side MECs are installed in a road side pole holding box, so that most of the road side MECs take DC direct current power supply as a preferred scheme.

DC power supply of road side industrial products mainly comprises DC12V, 9V-18V and DC24V, 18V-36V, but road side MEC is unstable or abnormal due to various factors in the process of construction debugging or long-term outdoor environment operation, so that an input protection circuit is generally required.

However, the protection circuit in the related art is liable to cause the occurrence of unstable or abnormal power supply input of the road side MEC due to the handling of various possible factors during the construction debug or the long-term outdoor environment operation.

Disclosure of Invention

The embodiment of the application provides a protection circuit for MEC direct current power supply input so as to reduce the risk of abnormal operation and even damage of MEC.

The embodiment of the application adopts the following technical scheme:

in a first aspect, an embodiment of the present application provides a protection circuit for MEC dc power input, where the protection circuit includes: a lightning surge protection circuit, a reverse connection protection circuit, a pulse group filter circuit and an undervoltage protection circuit,

the direct current power supply is input to the lightning protection surge circuit and supplies power to the MEC after passing through the reverse connection protection circuit, the pulse group filter circuit and the underovervoltage protection circuit.

In some embodiments, the anti-surge circuit is in series with the anti-reverse protection circuit, with the output of the anti-surge circuit being the input of the anti-reverse protection circuit.

In some embodiments, the anti-reverse protection circuit is in series with the pulse burst filter circuit, an output of the anti-reverse protection circuit being an input of the pulse burst filter circuit.

In some embodiments, the pulse-burst filter circuit is in series with the undervoltage protection circuit, the output of the pulse-burst filter circuit being the input of the undervoltage protection circuit.

In some embodiments, the output of the undervoltage protection circuit includes a supply operating voltage of 18V-36V, a rated operating current of 8A.

In some embodiments, the lightning surge protection circuit comprises a protection circuit consisting of a three-pole GDT gas discharge tube and an MOV piezoresistor, and a voltage clamping circuit consisting of a bidirectional TVS tube.

In some embodiments, the anti-reverse protection circuit comprises a PMOS anti-reverse circuit.

In some embodiments, the pulse group filter circuit comprises a pi-type filter circuit.

In some embodiments, the undervoltage protection circuit includes an undervoltage power-off protection circuit and an overvoltage power-off protection circuit.

In a second aspect, an embodiment of the present application further provides a roadside MEC, where the roadside MEC includes the protection circuit described above.

The above-mentioned at least one technical scheme that this application embodiment adopted can reach following beneficial effect: the protection circuit includes: the lightning protection surge circuit, the reverse connection protection circuit, the pulse group filter circuit and the undervoltage protection circuit enable the road side MEC to have the functions of lightning protection surge, reverse connection protection, anti-static pulse group and other interference false triggering, undervoltage protection, overvoltage protection and direct current supply voltage range adjustment. So that the road side MEC can cope with unstable or abnormal power supply input caused by various possible factors in the process of construction debugging or long-term outdoor environment operation.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute an undue limitation to the application. In the drawings:

fig. 1 is a schematic diagram of an internal structure of a protection circuit for MEC dc power input in an embodiment of the present application;

fig. 2 is a schematic diagram of circuit connection of a protection circuit for MEC dc power input in an embodiment of the present application;

FIG. 3 is a schematic circuit diagram of a lightning surge protection circuit according to an embodiment of the present application;

FIG. 4 is a schematic circuit diagram of an anti-reverse connection protection circuit according to an embodiment of the present application;

FIG. 5 is a schematic diagram of a pulse-burst filter circuit according to an embodiment of the present disclosure;

FIG. 6 is a schematic diagram of an undervoltage protection circuit according to an embodiment of the present application;

fig. 7 is a schematic circuit diagram of a protection circuit for MEC dc power input in an embodiment of the present application;

FIG. 8 is a schematic diagram of the overall circuit design cascade simulation result (input VIN) according to the embodiment of the present application;

fig. 9 is a schematic diagram of the cascade simulation result (output VOUT) of the overall circuit design according to the embodiment of the present application.

Detailed Description

For the purposes, technical solutions and advantages of the present application, the technical solutions of the present application will be clearly and completely described below with reference to specific embodiments of the present application and corresponding drawings. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

The inventor discovers when studying the roadside protection circuit, and in one scheme, the integrated chip is mainly an input protection circuit, such as a fuse chip or a hot plug controller chip. But for MEC (can be placed on road side), the scheme is not as mature and flexible as discrete device design in terms of cost selection, wide voltage input range, high current overcurrent capability, outdoor environment lightning surge pulse interference, protection function type, design difficulty, compatibility and the like. For example, for a road side MEC, a wide input range capability of 9V-36V and 8A may be required, but most of such chips in the market can be suitable for DC12V, which results in limited type selection, or basic functions such as high current, lightning surge and the like are realized by matching with a discrete device with larger control. The integrated chip which can be compatible with reverse connection prevention and overvoltage and undervoltage prevention is not good in shape selection, and the design is relatively complex. The clamp filtering of transient interference still needs to be realized by matching with a discrete device so as to meet the application scene of road side MEC, and the clamp filtering can resist short-time interference to normally work instead of frequent power failure.

In another scheme, the lightning surge, electrostatic pulse and reverse connection preventing functions are realized by discrete devices, but the functions of overvoltage and undervoltage protection and adjustable input voltage range are monitored by an MCU processor. However, for the road side MEC, constant power supply is required to be independently operated for a long term, the difficulty of updating and maintaining a software program is increased by introducing the MCU, the updating program of the brush machine cannot be frequently and manually assembled and disassembled, and the design difficulty and human resources are increased even if OTA is remotely updated. The adoption of a pure hardware circuit without software real-time sampling to realize independent monitoring protection is more suitable for road side MEC.

The inventor considers that the adoption of an integrated chip for designing a power supply input protection circuit for a road side MEC is not very beneficial, and the design is mature and flexible as discrete devices in the aspects of cost selection, wide voltage input range, large current overcurrent capacity, outdoor environment lightning surge pulse interference, protection function types, design difficulty, compatibility and the like. And the MCU is adopted to realize the functions of overvoltage and undervoltage protection and adjustable input voltage range, and the MCU program may need to be maintained and updated.

Aiming at the defects, the embodiment of the application provides a protection circuit for MEC direct current power supply input, which adopts a pure hardware circuit without software real-time sampling to realize independent monitoring protection. The protection circuit has the functions of lightning protection surge, reverse connection prevention, false triggering prevention of interference such as an antistatic pulse group and the like, undervoltage and overvoltage prevention and adjustable direct current power supply voltage range. So that the MEC used for the road side can cope with unstable or abnormal power supply input caused by various possible factors in the process of construction debugging or long-term outdoor environment operation, thereby reducing the risk of abnormal operation and even damage of the MEC used for the road side.

The following describes in detail the technical solutions provided by the embodiments of the present application with reference to the accompanying drawings.

The embodiment of the application provides a protection circuit for MEC dc power input, as shown in fig. 1, and provides a schematic structural diagram of a protection circuit 100 for MEC dc power input in the embodiment of the application, where the protection circuit at least includes a lightning protection surge circuit 110, a reverse connection protection circuit 120, a pulse group filter circuit 130, and an undervoltage protection circuit 140, and dc power is input to the lightning protection surge circuit 110 and is supplied to the MEC after passing through the reverse connection protection circuit 120, the pulse group filter circuit 130, and the undervoltage protection circuit 140.

The dc power is input to the surge protection circuit 110, and passes through the reverse connection protection circuit 120, the pulse group filter circuit 130, and the underovervoltage protection circuit 140, and the MEC is powered according to the output result of the underovervoltage protection circuit 140.

In one embodiment of the present application, the anti-lightning surge circuit 110 is connected in series with the anti-reverse protection circuit 120, and the output of the anti-lightning surge circuit is used as the input of the anti-reverse protection circuit.

As shown in fig. 2, the anti-surge circuit 110 is connected in series with the anti-reverse connection protection circuit 120, and then the output of the anti-surge circuit is used as the input of the anti-reverse connection protection circuit.

Namely, the protection circuit of the MEC direct current power supply input can prevent lightning and surge.

In one embodiment of the present application, the anti-reverse protection circuit 120 is connected in series with the pulse burst filter circuit 130, and the output of the anti-reverse protection circuit is used as the input of the pulse burst filter circuit.

As shown in fig. 2, after the anti-reverse protection circuit 120 is connected in series with the pulse group filter circuit 130, the output of the anti-reverse protection circuit is used as the input of the pulse group filter circuit.

Namely, the protection circuit of the MEC direct current power supply input can prevent reverse connection, prevent interference false triggering such as static pulse groups and the like.

In one embodiment of the present application, the pulse-burst filter circuit 130 is connected in series with the undervoltage protection circuit 140, with the output of the pulse-burst filter circuit being the input of the undervoltage protection circuit.

As shown in fig. 2, after the pulse-group filter circuit 130 is connected in series with the undervoltage protection circuit 140, the output of the pulse-group filter circuit is used as the input of the undervoltage protection circuit.

Namely, the protection circuit of the MEC direct current power supply input can prevent undervoltage and overvoltage and has the function of adjusting the direct current power supply voltage range.

In one embodiment of the present application, the output of the undervoltage protection circuit 140 includes a supply operating voltage of 18V-36V and a rated operating current of 8A.

Referring to fig. 8 and 9, simulation results are shown for a complex dc supply input V _in After being input to the processing of the protection circuit in the embodiment of the present application, the final output voltage V _out Meets the power supply scene requirement of MEC, can stably supply power at DC24V, 18V-36V and has the maximum stable working current capability of 8A.

In one embodiment of the application, the lightning surge protection circuit comprises a protection circuit consisting of a tripolar GDT gas discharge tube and an MOV piezoresistor, and a voltage clamping circuit consisting of a bidirectional TVS tube.

The MEC used on the road side is used as industrial-grade outdoor ITE information technology equipment and needs to be capable of bearing lightning surge interference, and according to national standard and application scene of GB/T17626.5-2019 electromagnetic compatibility test and measurement technology surge (impact) immunity test, a direct-current power supply line needs to be at least rated 3: line to line 1KV and line to ground 2KV. The lightning protection device used in the embodiment of the application is proved to be capable of meeting the level 4 through test verification: 2KV of the line-to-line and 4KV of the line-to-ground are adopted, and meanwhile, the method is also suitable for low-voltage application products within 60V.

Further, as shown in fig. 3, the specific circuit design is illustrated in detail by taking the DC24V, 18V-36V wide voltage range, and the 8A operation overcurrent capability as an example. The method is characterized in that a three-pole GDT gas discharge tube (3R 090A-5 SS) is connected in series with an MOV piezoresistor (14D 820 KJ) to conduct lightning surge high-voltage area differential mode common mode primary protection on a positive pole wire and a negative pole wire of direct current power supply, lightning surge current is discharged to PE ground through an MH1 shell screw hole site of MEC used for a road side, voltage after GDT1 discharge clamping is further clamped through a 36V bidirectional TVS (5.0SMDJ36CA) tube of D2, and finally transient voltage is clamped to be within 60V of low voltage for further processing of a later-stage protection circuit. The high-voltage area and the low-voltage area are isolated through common-mode inductance filtering with L1 (ACM 12V-701-2PL-TL 00) 8A overcurrent capacity, so that direct-current stable power supply is further optimized, and electromagnetic compatibility is improved.

In one embodiment of the present application, the anti-reverse connection protection circuit comprises a PMOS anti-reverse connection circuit.

As shown in fig. 4, the specific scheme circuit design is illustrated in detail by taking the DC24V, 18V-36V wide voltage range, and the 8A operation overcurrent capability as examples. In the process of installation and debugging, the MEC may cause the direct current power supply to be connected reversely and reversely due to improper operation and other reasons. In the embodiment of the application, a PMOS reverse connection preventing circuit is adopted to perform power-off processing on reverse connection error power supply. The PMOS type selection basic parameters can refer to technical data of related technologies, can meet the power supply application within 60V, and can stably work even if lightning surge residual current exists, and cannot be abnormal or damaged due to overcurrent impact. The on internal resistance of the PMOS type is only 10ohm, and the power consumption is only 0.64W even for the 8A operating steady state current.

In one embodiment of the present application, the pulse group filter circuit comprises a pi-type filter circuit.

As shown in fig. 5, the specific scheme circuit design is illustrated in detail by taking the DC24V, 18V-36V wide voltage range, and the 8A operation overcurrent capability as examples. After the DC24V is processed by the lightning surge circuit, possible transient high voltage is controlled within 60V. The MEC for the road side needs to stably and normally supply DC24V and 18V-36V for a long time in an outdoor road side environment, so electromagnetic compatibility needs to be further designed, and the MEC for the road side needs to have enough resistance to short-time transient interference outside the range of 18V-36V so as to ensure that the MEC for the road side stably supplies power and normally operates. Therefore, the design adopts pi-type filtering, such as C5/L2/C6, to further filter and clamp 60V pulse interference within a normal working voltage range, and further stably optimize direct current power supply electromagnetic compatibility (peripheral ceramic capacitor).

In one embodiment of the present application, the undervoltage protection circuit includes an undervoltage power-off protection circuit and an overvoltage power-off protection circuit.

As shown in fig. 6, the specific circuit design is illustrated in detail by taking the DC24V, 18V-36V wide voltage range, and the 8A operation overcurrent capability as examples. After the DC24V is processed by the pulse group filter circuit, transient interference such as lightning surge, static electricity, pulse interference and the like can be completely resisted, and low-voltage stable power supply is ensured.

However, for stable power supply, under-voltage power-off protection and over-voltage power-off protection are required in addition to reverse connection prevention power-off protection, so as to ensure normal power supply in the range of 18V-36V. The design adopts a pure discrete device circuit without software real-time sampling to realize independent monitoring protection. The base conduction voltage drop of BC846B is 0.58V-0.7V, the triode conduction voltage drop error is small, and the control precision is higher than that of the MOS tube.

Further, when dc=18v, the voltage applied to Q4 after passing through the R3& R8 voltage dividing resistor is just the base on voltage drop Vbe, so when the power supply is lower than 18V, Q4 is turned off, and Q2 is turned off due to vgs=0 (R7 is DNP null patch).

When dc=36V, the voltage applied to Q3 after voltage division by D4& R5& R6 is just the base on voltage drop Vbe, so that when the power supply is greater than 36V, Q3 is turned on, and then Q4 is turned off, and finally Q2 is turned off due to vgs=0 (R7 is DNP null).

R7 has no functions of under-voltage and over-voltage protection and adjustable voltage range if the patch is used. The maximum power consumption of each resistor is not more than 0.05mW; d3 is used to protect the Q2 gate-source Vgs limit voltage; c11 is used for filtering anti-interference, and Q2 is prevented from being conducted by mistake; c12 is used for clamping, delaying and stabilizing to conduct Q3, so that power supply input is prevented from supplying power again for a short time under the condition of high-voltage power failure, and output burrs are avoided.

As shown in fig. 7, the schematic circuit diagram of the whole circuit design cascade connection, besides MEC, can also perform optimization fine tuning for products with similar requirements, and is flexible, convenient and reliable in shape selection substitution for cost saving, electromagnetic compatibility and other aspects.

The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and changes may be made to the present application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. which are within the spirit and principles of the present application are intended to be included within the scope of the claims of the present application.

Claims

1. A protection circuit for an MEC dc supply input, wherein the protection circuit comprises: the anti-lightning surge circuit, the anti-reverse connection protection circuit, the pulse group filter circuit and the underovervoltage protection circuit are connected in series, and direct current power is input to the anti-lightning surge circuit and is supplied to the MEC after passing through the anti-reverse connection protection circuit, the pulse group filter circuit and the underovervoltage protection circuit.

2. The protection circuit of claim 1, wherein the anti-lightning surge circuit is in series with the anti-reverse protection circuit, an output of the anti-lightning surge circuit being an input of the anti-reverse protection circuit.

3. The protection circuit of claim 1, wherein the anti-reverse protection circuit is in series with the pulse burst filter circuit, an output of the anti-reverse protection circuit being an input of the pulse burst filter circuit.

4. The protection circuit of claim 1, wherein the pulse-burst filter circuit is in series with the undervoltage protection circuit, an output of the pulse-burst filter circuit being an input of the undervoltage protection circuit.

5. The protection circuit of claim 4, wherein the output of the undervoltage protection circuit comprises a supply operating voltage of 18V to 36V, a rated operating current of 8A.

6. The protection circuit of claim 1, wherein the lightning surge protection circuit comprises a protection circuit consisting of a three-pole GDT gas discharge tube and an MOV varistor, and a voltage clamping circuit consisting of a bi-directional TVS tube.

7. The protection circuit of claim 1, wherein the anti-reverse connection protection circuit comprises a PMOS anti-reverse connection circuit.

8. The protection circuit of claim 1, wherein the pulse group filter circuit comprises a pi filter circuit.

9. The protection circuit of claim 1, wherein the undervoltage protection circuit comprises an undervoltage power-down protection circuit and an overvoltage power-down protection circuit.

10. A MEC comprising the protection circuit of any one of claims 1 to 9.