CN201263086Y - DC power supply and lightning protection circuit for the same - Google Patents

Abstract

The utility model provides a DC power supply and a lightning protection circuit for the DC power supply, wherein the lightning protection circuit for the DC power supply includes: a D-level lightning protection circuit; a C-level lightning protection circuit; and a differential mode Inductive decoupling circuit in the form; the C-level lightning protection circuit, the D-level lightning protection circuit and the decoupling circuit are all arranged on the circuit board of the DC power supply; the D-level lightning protection circuit and the C-level lightning protection circuit The circuits are connected in series through the decoupling circuit. The utility model connects the C-level lightning protection circuit in series with the D-level lightning protection circuit through the decoupling circuit to form a two-level lightning protection circuit for DC power supply. When there is a lightning strike, it not only realizes the overvoltage protection of the equipment itself, but also It can effectively protect the DC power supply from damage. The utility model has the advantages of simple structure and low cost, and can be widely applied to the power board of the DC base station.

Description

A DC power supply and a lightning protection circuit for the DC power supply

technical field

The utility model relates to lightning protection technology, in particular to a DC power supply and a lightning protection circuit for the DC power supply of a DC input base station.

Background technique

At present, the lightning protection of outdoor base stations is above C level, which involves the cascading of C level and D level lightning protection. The ideal state is to let the C level lightning protection respond first when the induced lightning current invades. , discharge most of the lightning current, and then enter the D-level lightning protection response. Although the C-level lightning protection circuit is placed in front of the D-level lightning protection circuit, the actual situation is that the lightning current first enters the heavy load end, that is, the D-level lightning protection and load end, which often makes the lightning protection protection invalid. An effective way to solve this problem is to increase decoupling.

The previous method of increasing decoupling is: put the C-level lightning protection box into the system box or specially configure an external lightning protection box. If a lightning protection box is added, there is a certain distance between the lightning protection box and the whole machine (generally 5 to 15 meters), so the decoupling due to the inductance of the cable itself is enough to solve the cascading problem; Into the system, reserve space in the lightning protection box or in the system, and use the air-core inductor formed by the self-winding of the cable to complete the decoupling.

With the development trend of high integration and miniaturization of outdoor communication base stations, new challenges are posed to the installation of lightning arresters, especially for the lightning protection of DC input base stations, there is a tendency to introduce them to power boards.

However, due to technical difficulties and potential risks, the lightning protection on the DC power board, the equipment manufacturers can only achieve D-level lightning protection at most, which only solves the overvoltage protection of the equipment itself, and most of them do not implement C-level lightning protection. into the power board.

Utility model content

In order to solve the two-level lightning protection problem of DC power supply, the utility model provides a DC power supply lightning protection circuit, including:

Class D lightning protection circuit;

Also includes:

Class C lightning protection circuit; and

Inductive decoupling circuit in the form of differential mode;

The C-level lightning protection circuit, the D-level lightning protection circuit and the decoupling circuit are all arranged on the circuit board of the DC power supply;

The D-level lightning protection circuit is connected in series with the C-level lightning protection circuit through the decoupling circuit.

The C-level lightning protection circuit includes: piezoresistors VR1, VR2, discharge tube FV1 and fuse F1;

The D-level lightning protection circuit includes: piezoresistors VR3 and VR4;

The decoupling circuit includes: differential mode inductors L1, L2;

One end of the first circuit formed by VR1 is connected to the positive end of the power supply, and the other end is connected to the negative end of the power supply through a series fuse F1;

The second circuit formed by the VR2 and the FV1 in series is connected in parallel with the first circuit;

The common end of the VR2 and the FV1 is connected to the ground terminal PE;

One end of the L1 is connected to one end of the second circuit, and the other end is connected to one end of the VR3;

One end of the L2 is connected to the other end of the second circuit, and the other end of the L2 is connected to the other end of the VR3;

The VR4 is connected in parallel with the VR3;

One end of the VR4 is respectively connected to the input terminal VIN+ of the power module M1 and the input terminal VIN+ of the power module M2 through the differential mode inductors L3 and L4;

The other end of the VR4 is directly connected to the input terminal VIN- and the enabling terminal CNT of the power module M1, and to the input terminal VIN- and the enabling terminal CNT of the power module M2, respectively.

The lightning protection circuit for DC power supply also includes:

EMI circuits;

Fuse F2;

The other end of the L1 is connected to one end of the VR3 through an input end of the electromagnetic interference circuit;

The other end of the L2 is connected to the other end of the VR3 through another input end of the electromagnetic interference circuit;

One end of the L2 is connected to the other end of the second circuit through the fuse F2.

The decoupling inductance of the inductive decoupling circuit is a magnetic core inductance.

The present invention also provides a DC power supply, comprising:

DC power circuit board;

A class D lightning protection circuit arranged on the DC power supply circuit board;

Also includes:

A class C lightning protection circuit arranged on the DC power supply circuit board; and

A differential-mode inductive decoupling circuit disposed on the DC power circuit board;

The D-level lightning protection circuit is connected in series with the C-level lightning protection circuit through the decoupling circuit.

The decoupling inductance of the inductive decoupling circuit is a magnetic core inductance.

The C-level lightning protection circuit includes: piezoresistors VR1, VR2, discharge tube FV1 and fuse F1;

The D-level lightning protection circuit includes: piezoresistors VR3 and VR4;

The decoupling circuit includes: differential mode inductors L1, L2;

One end of the first circuit formed by VR1 is connected to the positive end of the power supply, and the other end is connected to the negative end of the power supply through a series fuse F1;

The second circuit formed by the VR2 and the FV1 in series is connected in parallel with the first circuit;

The common end of the VR2 and the FV1 is connected to the ground terminal PE;

One end of the L1 is connected to one end of the second circuit, and the other end is connected to one end of the VR3;

One end of the L2 is connected to the other end of the second circuit, and the other end of the L2 is connected to the other end of the VR3;

The VR4 is connected in parallel with the VR3;

One end of the VR4 is respectively connected to the input terminal VIN+ of the power module M1 and the input terminal VIN+ of the power module M2 through the differential mode inductors L3 and L4;

The other end of the VR4 is directly connected to the input terminal VIN- and the enabling terminal CNT of the power module M1, and to the input terminal VIN- and the enabling terminal CNT of the power module M2, respectively.

The DC power supply also includes:

EMI circuits;

Fuse F2;

The other end of the L1 is connected to one end of the VR3 through an input end of the electromagnetic interference circuit;

The other end of the L2 is connected to the other end of the VR3 through another input end of the electromagnetic interference circuit;

One end of the L2 is connected to the other end of the second circuit through the fuse F2.

Compared with the prior art, the utility model has the following beneficial effects:

The utility model connects the C-level lightning protection circuit in series with the D-level lightning protection circuit through the decoupling circuit to form a two-level lightning protection circuit for DC power supply. When there is a lightning strike, it not only realizes the overvoltage protection of the equipment itself, but also It can effectively protect the DC power supply from damage. The utility model has the advantages of simple structure and low cost, and can be widely applied to the power board of the DC base station.

Description of drawings

Fig. 1 is the structural representation of the utility model two-stage lightning protection circuit;

Fig. 2 is the circuit diagram of the utility model embodiment;

Fig. 3 is a schematic diagram of the flow of lightning current and load current during counterattack and normal strike.

Detailed ways

The utility model belongs to an overvoltage protection device, which is a protection measure for the lightning intrusion wave at the power supply port, and is suitable for the protection of the induced lightning field generated by the lightning electromagnetic field, and is applied to the LPZ1-LPZ2 areas of the divisional lightning protection.

On the basis of retaining the original D-level lightning protection circuit, the utility model introduces the C-level lightning protection circuit into the DC power supply printed circuit board (PCB, Printed circuit board), and the C-level lightning protection circuit and the D-level lightning protection circuit The decoupling circuit is connected in series to ensure that the C-level lightning protection circuit operates first when the induction lightning is applied to the input terminal.

Below in conjunction with accompanying drawing, the specific embodiment of the present utility model is described in further detail.

When lightning strikes, the system couples part of the lightning strike current. In order to ensure that most of the lightning strike current is discharged through the front-stage (C-level) lightning arrester, and the rear-stage (D-level) only discharges a small part, this requires coordination between the front and rear stages. Complete energy distribution (energy coordination), the block diagram of Fig. 1 is described as follows to graded lightning protection below: Fig. 1 is the structure diagram of two-stage lightning protection circuit of the present utility model, D level lightning protection circuit is connected with C level lightning protection circuit by decoupling circuit Lightning circuit in series. Among them, the decoupling circuit is composed of differential mode inductors, which are used to complete the inter-level matching and energy distribution of C-level and D-level lightning strike currents, so as to ensure that C level discharges first and then D level discharges. C-level and D-level lightning protection circuits use C-level and D-level surge protectors (Surge Protection Device, SPD) respectively.

Referring to FIG. 2, FIG. 2 is a circuit diagram of an embodiment of the present invention. The piezoresistors VR1, VR2, discharge tube FV1 and fuse F1 in Figure 2 constitute a Class C lightning protection circuit; the piezoresistors VR3 and VR4 constitute a Class D lightning protection circuit, and the differential mode inductors L1, L1, and L2 is used to complete the inter-level matching and energy distribution of the lightning strike current between the C level and the D level, so as to ensure that the C level discharges first, and the D level discharges again.

There is an Electromagnetic Interference (EMI) circuit in series between the differential mode inductors L1, L2 and the D-level lightning protection. The EMI circuit generally includes two stages: a differential-mode filter circuit and a common-mode filter circuit. Both circuits are non-power conversion circuit. The function of this circuit is to prevent the radiation of the power grid from entering the system, and at the same time, the radiation of the system does not enter the power grid, that is, it plays the role of preventing radiation and isolating.

One end of the first circuit constituted by VR1 is connected to VCC48VGND, and the other end is connected to VCC48VN through a serial fuse F1. The second circuit composed of VR2 and FV1 in series is connected in parallel with the first circuit. The common end of VR2 and FV1 is connected to the ground terminal PE. One end of L1 is connected to one end of the second circuit, and the other end of L1 is connected to one end of VR3 through an input end of the EMI filter circuit. One end of L2 is connected to the other end of the second circuit through a fuse F2. The other end of L2 is connected to the other end of VR3 through the other input end of the EMI filter circuit.

VR4 and VR3 are connected in parallel to form a third circuit, which is a Class D lightning protection circuit.

One end of VR4 is connected to the input terminal VIN+ of the power module M1 and the input terminal VIN+ of the power module M2 through L3 and L4 respectively. The other end of VR4 is directly connected to the input terminal VIN- and the enabling terminal CNT of the power module M1, and to the input terminal VIN- and the enabling terminal CNT of the power module M2, respectively.

Among them, the fuse F1 constitutes a lightning protection circuit. Its function is to prevent its failure and effectively protect the subsequent load by using a suitable fuse F1 connected in series with VR1 in the event of a short-circuit failure mode after aging of the piezoresistors VR1 and VR2. When choosing F1, pay attention: the current capacity parameter must be large enough to meet the impact of the maximum 20KA (8/20US) lightning current.

L1 and L2 form a decoupling circuit. The decoupling circuit is introduced in the form of differential mode, adopts magnetic core inductive coupling, and the flux current is large enough to not cause the magnetic core to saturate. The inductance is between 33 and 38uH. The differential mode inductors L1 and L2 also take into account the power conduction disturbance function. The selection of the inductance magnetic core should choose the magnetic core with a small magnetic permeability as much as possible. Generally, the value is between 100 and 200, and the Curie temperature is relatively high. The inductance cannot be introduced in the form of common mode.

PE is the ground terminal, so that the whole circuit becomes an equipotential body.

The role of F2 is to estimate the fuse needed to complete the fine protection of the load according to the working voltage range and power. It is not necessary for the lightning protection circuit. One end of L2 can also be directly connected to the other end of VR1.

The EMI filter circuit is not necessary for lightning protection. If there is no EMI circuit, the other end of L1 is directly connected to one end of VR3, and the other end of L2 is directly connected to the other end of VR3.

Differential mode inductors L3 and L4 constitute an anti-interference circuit, which is used to keep the energy of the power modules M1 and M2 continuous, that is, to suppress the sag of the power supply voltage, especially to prevent the power supply voltage from instantly dropping to the minimum input voltage allowed by the power module when the lightning current strikes back. The power module has no output intermittently, causing the load to reset, and then the established communication link is interrupted. Refer to Figure 3 for a schematic diagram of the flow of lightning current and load current during counterattack and normal strike. In Fig. 3, the solid line arrow is the load current, the dotted line arrow is the positive lightning current, and the double-dot dash line arrow is the counter lightning current. In differential mode induction lightning, if the load current is in the same direction as the lightning current, we call it a positive lightning strike, that is, a positive strike; if the load current is in the opposite direction to the lightning current, we call it a negative polarity lightning strike, that is, a counterattack.

The working principle of the circuit shown in Figure 3 is: if the induced lightning invades the power port VCC in the positive polarity differential mode, the piezoresistor VR1 acts before VR3 due to the existence of the energy storage inductor of L1; thus VR1 discharges most of the lightning Current, at the moment VR1 is turned on, part of the residual voltage (lightning current) passes through L1 to make the varistor VR3 turn on and flow back to L2 (at this time, the lightning current is in the same direction as the applied voltage and current), thus effectively protecting the subsequent load M1, M2 ensures uninterrupted (ie no reset) operation of the system within the normal power supply range. Similarly, when the induced lightning invades the power port VCC in the form of negative polarity differential mode, due to the existence of L2, VR1 acts before VR3, so that part of the residual voltage enters VR3 through L2 and flows back to L1 (this time the lightning current is opposite to the applied power supply current), The subsequent loads M1 and M2 are also protected. This time, due to the negative polarity of the lightning current, the external normal power supply voltage tends to decrease, but due to the existence of anti-interference circuits L3 and L4, the power supply voltage of MI and M2 loads does not decay too quickly, and because the module shutdown function adopts negative logic , so as to ensure the normal operation of the module.

If the induced lightning invades the power port VCC in the positive polarity common mode, the voltage limiting protection device-the discharge tube FV1 completes the C-level lightning current discharge to PE, and at this time L1 still plays the role of decoupling. If the induced lightning invades the VCC of the power port in the form of negative common mode, VR2 completes the C-class lightning current discharge to PE, and L2 still plays the role of decoupling. The role of VR4 is to share a part of the lightning current for VR3, and it can also not be used. At this time, one end of VR3 is connected to the input terminal VIN+ of the power module M1 and the input terminal VIN+ of the power module M2 through L3 and L4 respectively. The other end of VR3 is directly connected to the input terminal VIN- and the enabling terminal CNT of the power module M1, and to the input terminal VIN- and the enabling terminal CNT of the power module M2, respectively.

Of course, in order to suppress the function of voltage sag, L3 and L4 can also be replaced with capacitors. By using the characteristic that the capacitor voltage cannot jump, it is also possible to ensure that the input voltage is not lower than the rated input voltage of the power module. The greater the capacitance drop The smaller the input capacitance is, the larger the input capacitance is. It has been confirmed by a large number of experiments: the allowed capacitance can only achieve the maximum differential mode counterattack of 10KA (8/20US) without reset, and will affect other indicators , therefore, it is better to use an inductor instead of a capacitor.

Although the introduction of inductors L1 and L2 can produce decoupling effects, they will have an impact on the conduction disturbance of the power supply's Electromagnetic Compatibility (EMC) index in the low-frequency band (mainly below 1MKZ), which can be achieved by adopting a certain For example, under the premise of not affecting the safety test, the capacitance of the differential mode capacitor X or the capacitance of the common mode capacitor Y in the differential mode filter circuit or common mode filter circuit can be appropriately increased to offset its band coming impact. Moreover, X capacitors are not allowed to be added to the front ends of the inductors L1 and L2, because the lightning current wave is a frequency wave, and the withstand voltage level of the existing devices on the market does not meet the requirements.

It should be noted that the decoupling inductor should be avoided to be connected behind the EMI filter circuit, that is, between the EMI filter circuit and the D-level lightning protection circuit, because this is likely to cause the EMI common mode filter circuit to be saturated and cannot achieve decoupling. effect.

It is best to use the Kevin connection method for the lightning protection wiring on the power board to minimize the resistance of the varistor and the discharge tube. At the same time, pay attention to the wiring width and safety insulation distance.

The above is only a preferred embodiment of the utility model, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the utility model, some improvements and modifications can also be made. These improvements and modifications It should also be regarded as the protection scope of the present utility model.

Claims (8)

1. A lightning protection circuit for DC power supply, comprising: Class D lightning protection circuit; It is characterized in that it also includes: Class C lightning protection circuit; and Inductive decoupling circuit in differential mode; The C-level lightning protection circuit, the D-level lightning protection circuit and the decoupling circuit are all arranged on the circuit board of the DC power supply; The D-level lightning protection circuit is connected in series with the C-level lightning protection circuit through the decoupling circuit. 2. The lightning protection circuit for DC power supply as claimed in claim 1, wherein the Class C lightning protection circuit comprises: piezoresistors VR1, VR2, discharge tube FV1 and fuse F1; The D-level lightning protection circuit includes: piezoresistors VR3 and VR4; The decoupling circuit includes: differential mode inductors L1, L2; One end of the first circuit formed by VR1 is connected to the positive end of the power supply, and the other end is connected to the negative end of the power supply through a series fuse F1; The second circuit formed by the VR2 and the FV1 in series is connected in parallel with the first circuit; The common end of the VR2 and the FV1 is connected to the ground terminal PE; One end of the L1 is connected to one end of the second circuit, and the other end is connected to one end of the VR3; One end of the L2 is connected to the other end of the second circuit, and the other end of the L2 is connected to the other end of the VR3; The VR4 is connected in parallel with the VR3; One end of the VR4 is respectively connected to the input terminal VIN+ of the power module M1 and the input terminal VIN+ of the power module M2 through the differential mode inductors L3 and L4; The other end of the VR4 is directly connected to the input terminal VIN- and the enabling terminal CNT of the power module M1, and to the input terminal VIN- and the enabling terminal CNT of the power module M2, respectively. 3. The lightning protection circuit for DC power supply as claimed in claim 2, further comprising: EMI circuits; Fuse F2; The other end of the L1 is connected to one end of the VR3 through an input end of the electromagnetic interference circuit; The other end of the L2 is connected to the other end of the VR3 through another input end of the electromagnetic interference circuit; One end of the L2 is connected to the other end of the second circuit through the fuse F2. 4. The lightning protection circuit for a DC power supply according to claim 1, wherein the decoupling inductance of the inductive decoupling circuit is a magnetic core inductance. 5. A DC power supply, comprising: DC power circuit board; A class D lightning protection circuit arranged on the DC power supply circuit board; It is characterized in that it also includes: A class C lightning protection circuit arranged on the DC power supply circuit board; and A differential-mode inductive decoupling circuit disposed on the DC power circuit board; The D-level lightning protection circuit is connected in series with the C-level lightning protection circuit through the decoupling circuit. 6. The DC power supply according to claim 5, wherein the decoupling inductance of the inductive decoupling circuit is a magnetic core inductance. 7. The DC power supply according to claim 5, wherein the Class C lightning protection circuit comprises: piezoresistors VR1, VR2, discharge tube FV1 and fuse F1; The D-level lightning protection circuit includes: piezoresistors VR3 and VR4; The decoupling circuit includes: differential mode inductors L1, L2; One end of the first circuit formed by VR1 is connected to the positive end of the power supply, and the other end is connected to the negative end of the power supply through a series fuse F1; The second circuit formed by the VR2 and the FV1 in series is connected in parallel with the first circuit; The common end of the VR2 and the FV1 is connected to the ground terminal PE; One end of the L1 is connected to one end of the second circuit, and the other end is connected to one end of the VR3; One end of the L2 is connected to the other end of the second circuit, and the other end of the L2 is connected to the other end of the VR3; The VR4 is connected in parallel with the VR3; One end of the VR4 is respectively connected to the input terminal VIN+ of the power module M1 and the input terminal VIN+ of the power module M2 through the differential mode inductors L3 and L4; The other end of the VR4 is directly connected to the input terminal VIN- and the enabling terminal CNT of the power module M1, and to the input terminal VIN- and the enabling terminal CNT of the power module M2, respectively. 8. The DC power supply according to claim 7, further comprising: EMI circuits; Fuse F2; The other end of the L1 is connected to one end of the VR3 through an input end of the electromagnetic interference circuit; The other end of the L2 is connected to the other end of the VR3 through another input end of the electromagnetic interference circuit; One end of the L2 is connected to the other end of the second circuit through the fuse F2.

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