CN215870754U

CN215870754U - Circuit for inhibiting instantaneous overcurrent on power-on of electric equipment

Info

Publication number: CN215870754U
Application number: CN202121648954.5U
Authority: CN
Inventors: 王芳; 桑海英; 周斌
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-07-19
Filing date: 2021-07-19
Publication date: 2022-02-18
Anticipated expiration: 2031-07-19

Abstract

The utility model discloses a circuit for inhibiting the power-on instantaneous overcurrent of electric equipment, which comprises: the circuit includes: the input end of the first resistor is connected to the positive electrode of a power supply, the output end of the first resistor is connected to the emitting electrode of a first triode, the base electrode of the first triode is connected with a digital ground through a second resistor, the base electrode is connected to the output end of the first resistor through a first diode and a second diode which are connected in series, the collector electrode of the first triode is connected to one end of a first inductor, one end of a first capacitor is connected to the collector electrode of the first triode, the other end of the first capacitor is connected to the digital ground, a second capacitor is connected between the other end of the first inductor and the digital ground, the first capacitor, the first inductor and the second capacitor form a pi-type low-pass filter, the first triode is a PNP-type triode, and the first resistor and the second resistor are metal film resistors.

Description

Circuit for inhibiting instantaneous overcurrent on power-on of electric equipment

Technical Field

The utility model relates to the technical field of circuits, in particular to a circuit for inhibiting instantaneous overcurrent of power-on electric equipment.

Background

In the design of a power circuit in the field of electromechanical control, due to the limitation of the driving capability of a power system, the current of a power-on instant of a power-on device needs to be limited so as to avoid the fault of the power system or the fault that the power-on device cannot work due to the insufficient driving capability of the power system. As shown in fig. 1, the existing circuit usually adopts a current limiting design in which a high-power resistor is connected in series at the foremost power input end, i.e. the front end of an input capacitor, and the current limiting design is used at the moment of powering on the electric equipment.

SUMMERY OF THE UTILITY MODEL

In view of the defects of the prior art, the utility model provides a novel circuit for inhibiting the instant overcurrent during the power-on of the electric equipment, which limits the impact current on the electric equipment, avoids the damage of the instant impact current to the overcurrent of the equipment, lightens the load of a power supply system and improves the stability and the safety of the circuit.

The technical scheme adopted by the utility model is as follows: a circuit for suppressing transient overcurrent on a powered device, the circuit comprising: the input end of the first resistor is connected to the positive electrode of a power supply, the output end of the first resistor is connected to the emitting electrode of a first triode, the base electrode of the first triode is connected with a digital ground through a second resistor, the base electrode is connected to the output end of the first resistor through a first diode and a second diode which are connected in series, the collector electrode of the first triode is connected to one end of a first inductor, one end of a first capacitor is connected to the collector electrode of the first triode, the other end of the first capacitor is connected to the digital ground, a second capacitor is connected between the other end of the first inductor and the digital ground, the first capacitor, the first inductor and the second capacitor form a pi-type low-pass filter, the first triode is a PNP-type triode, and the first resistor and the second resistor are metal film resistors.

Has the advantages that:

the circuit design scheme for restraining the instantaneous overcurrent of the power-on equipment ensures that the current at the moment of power-on has little difference with the normal working current, basically maintains the original load of a power supply system, and realizes the effect of restraining the instantaneous impact current of power-on. The output voltage at the rear end of the inductor is about +14.5V, so that the normal use of an operational amplifier, a voltage reference source, a frequency-voltage conversion chip or a comparator chip in a general rear-stage circuit can be met, and the problem of insufficient power supply voltage of a rear-stage energy supply circuit is solved.

Drawings

In order to more clearly illustrate the embodiments of the present application or technical solutions in the prior art, the drawings used in the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments described in the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings.

FIG. 1 is a diagram of a conventional power input circuit;

fig. 2 is a diagram of a power input circuit provided by the present invention.

The utility model is further described below with reference to the figures and the specific examples.

Detailed Description

As shown in fig. 2, a circuit for suppressing an overcurrent at a power-on moment of a power-on device, the circuit includes: a first resistor 1R1, the input terminal of which is connected to the positive power supply IN +, the output terminal of which is connected to the emitter of a first PNP type triode 1V1, the base of which is connected to the digital DGND through a second resistor 1R4, the base of which is connected to the output terminal of a first resistor 1R1 through a first diode 1V2 and a second diode 1V3 connected IN series, the collector of the first PNP type triode 1V1 is connected to one end of a first inductor 1L1, a first capacitor 1C1 is connected at one end to the collector of a first PNP type triode 1V1 and at the other end to the digital DGND, a second capacitor 1C2 is connected between the other end of the first inductor 1L1 and the digital DGND, and the first capacitor 1C1, the first inductor 1L1 and the second capacitor 1C2 constitute a pi-type filter. The power supply voltage is +15V, the first resistor 1R1 and the second resistor 1R4 are metal film resistors, the first resistor 1R1 is 20 Ω, and the second resistor 1R4 is 10K Ω.

The disclosed circuit utilizes a PNP transistor (3CG180B) for current limiting using common base connection. At the moment of powering on the circuit, since there is no voltage on the capacitor 1C1, the voltage Vce between the collector and emitter of the transistor is much greater than its minimum on voltage, and at this time the transistor operates in a linear amplification region with an amplification factor of approximately 1. The actual conduction voltage drop of the two diodes 1V2 and 1V3 is 0.6 × 2 to 1.2V, the voltage at the upper end of the resistor 1R4 is clamped to about 13.8V, and the voltage Vbe between the base and the emitter of the triode is saturated and dropped to 0.85V, so that the voltage drop across the resistor 1R1 is 1.2-0.85 to 0.35V, and the current flowing through R1 is 0.35/20 to 17.5 mA. The amplification factor of the triode is close to 1, the amplification current, namely the output current of the triode is close to 17.5mA, and therefore the circuit charges the capacitor with a circuit of 17.5 mA. The bus current is divided into two parts, one part is capacitor charging current, the other part is current 13.8V/10000 omega flowing through 1R4 which is 1.38mA, therefore, the total current is 1.38+17.5 which is 18.88mA, and the current is about 25mA in normal operation, the current at the moment of electrifying and the normal operation current have little difference, the load of a power supply system cannot be increased, and the effect of inhibiting the impact current at the moment of electrifying is realized. Experiments show that a 1 omega resistor is connected in series at the power supply inlet of the electric equipment, an oscilloscope is used for capturing the voltage on the 1 omega resistor at the moment of electrifying, the working current of the electric equipment is about 25mA, and the impact current higher than the normal working current by 25mA does not appear at the moment of electrifying, so that the effect of inhibiting the impact current is realized. IN addition, after the tube voltage of the triode is reduced, the actually measured voltage output by the rear end of the inductor 1L1 is about +14.5V, so that the normal use of an operational amplifier, a voltage reference source, a frequency-voltage conversion chip or a comparator chip IN a general rear-stage circuit can be met, and the problem of insufficient power supply voltage of a rear-stage power supply circuit is solved.

In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the utility model may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

It should be noted that: the above-described embodiments are illustrative of the present invention and are not restrictive thereof, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps or the like not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The utility model may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.

Claims

1. A circuit for suppressing transient overcurrent on a powered device, the circuit comprising: the input end of the first resistor is connected to the positive electrode of a power supply, the output end of the first resistor is connected to the emitting electrode of a first triode, the base electrode of the first triode is connected with a digital ground through a second resistor, the base electrode is connected to the output end of the first resistor through a first diode and a second diode which are connected in series, the collector electrode of the first triode is connected to one end of a first inductor, one end of a first capacitor is connected to the collector electrode of the first triode, the other end of the first capacitor is connected to the digital ground, a second capacitor is connected between the other end of the first inductor and the digital ground, the first capacitor, the first inductor and the second capacitor form a pi-type low-pass filter, the first triode is a PNP-type triode, and the first resistor and the second resistor are metal film resistors.

2. The circuit for suppressing power-on transient overcurrent of an electric device as set forth in claim 1, wherein the voltage of the positive electrode of the power supply is +15V, the first resistor is 20 Ω, and the second resistor is 10K Ω.