WO2016090555A1

WO2016090555A1 - Overcurrent protection circuit

Info

Publication number: WO2016090555A1
Application number: PCT/CN2014/093374
Authority: WO
Inventors: 刘春红; 黄鹤鸣; 肖灵
Original assignee: 深圳市聚作照明股份有限公司
Priority date: 2014-12-09
Filing date: 2014-12-09
Publication date: 2016-06-16

Abstract

An overcurrent protection circuit (100) is connected between a low-voltage DC power supply (200) and a load (300). The circuit includes: an overcurrent circuit breaker (101), an input end thereof is connected to an output end of the low-voltage DC power supply (200); a current detection module (102), an input end thereof is connected to an output end of the overcurrent circuit breaker (101), an output end thereof is connected to an input end of the load (300), and a triggering end thereof outputs a triggering voltage when the voltage drop of the current detection module (102) exceeds a threshold value; a voltage-dividing module (103), one end thereof is connected to the triggering end of the current detection module (102), and the other end is connected to the ground; and a unidirectional silicon controlled rectifier (D1), the anode thereof is connected to the input end of the current detection module (102), the control electrode thereof is connected to the triggering end of the current detection module (102), and the cathode thereof is connected to the ground. When the load has a fault, the current of a main loop is increased, and when the voltage drop of the current detection module exceeds the threshold value, the triggering voltage is sent out, so that the unidirectional silicon controlled rectifier is turned on, the input end of the load is short connected to the ground, and at this moment a large current is generated to enable the overcurrent circuit breaker to be fused, thereby cutting off the power supply of the main loop, effectively protecting electric appliances, and reducing the possibility of fire.

Description

Overcurrent protection circuit

Technical field

The utility model relates to the field of overcurrent protection, in particular to an overcurrent protection circuit.

Background technique

In the DC-DC (DC converter) low-voltage conversion circuit, since the supply voltage is DC low voltage, generally 60VDC or less, DC - When the DC conversion circuit fails, the front-end fuse is not easily disconnected, which may cause the components to slowly heat up and burn the circuit board and equipment, and even cause a fire.

technical problem

The utility model provides an overcurrent protection circuit, which solves the problem that the fuse is not easy to be triggered when the DC low voltage power supply is in the prior art, and the circuit is easily destroyed.

Technical solution

The utility model provides an overcurrent protection circuit which is connected between a low voltage DC power source and a load, and comprises:

The overcurrent circuit breaker component has an overcurrent fuse function, and the input end thereof is connected to the output end of the low voltage DC power source;

a current detecting module, the input terminal is connected to the output end of the overcurrent circuit breaker device, and the output terminal is connected to the input end of the load, and when the voltage drop of the current detecting module exceeds a threshold, the trigger voltage is output at the trigger end;

The voltage dividing module has one end connected to the trigger end of the current detecting module and the other end grounded;

The unidirectional thyristor has an anode connected to the input end of the current detecting module, a control pole connected to the trigger end of the current detecting module, and a cathode grounded.

Preferably, the current detecting module comprises a sampling resistor and a PNP type transistor, and the first end of the sampling resistor is connected as an input end of the current detecting module to an output end of the overcurrent circuit breaker member, and is connected to an emitter of the triode The second end of the sampling resistor serves as an input end of the current detecting module to the input end of the load, and is connected to the base of the transistor, and the collector of the transistor serves as a trigger end of the current detecting module.

Preferably, the triode is a small patch transistor of SOT23 package.

Preferably, the voltage dividing module comprises a voltage dividing resistor and a voltage stabilizing capacitor, wherein the voltage dividing resistor is connected to one end of the collector of the triode and the other end is grounded, and the voltage stabilizing capacitor is connected in parallel with the voltage dividing resistor.

Preferably, the voltage dividing resistor is a chip resistor.

Preferably, the voltage stabilizing capacitor is a chip capacitor.

Preferably, the overcurrent circuit breaker component is a fuse or a fuse.

Preferably, the low-voltage DC power supply comprises an EMI rectification filter circuit, an isolated single-stage PFC circuit and a rectification filter circuit, which are connected in sequence, the EMI rectification filter circuit is connected to an AC power source, and the rectification filter circuit outputs a low-voltage DC power.

Preferably, the load is a DC-DC conversion circuit.

Beneficial effect

When the overcurrent protection circuit fails due to the load, the current of the main circuit increases, and when the voltage drop exceeds the threshold value on the current detecting module, a trigger voltage is issued to make the unidirectional thyristor turn on, and the input end of the load is shorted to the ground. At this time, a large current is generated to melt the overcurrent circuit breaker, cut off the power supply of the main circuit, effectively protect the electrical appliance, and reduce the possibility of fire; the circuit has fewer components, lower cost and high practicability.

DRAWINGS

1 is a circuit structural diagram of an overcurrent protection circuit in a preferred embodiment of the present invention.

Embodiments of the invention

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Please refer to FIG. 1. In this embodiment, the overcurrent protection circuit 100 is connected to the low voltage DC power supply 200 and the load. Between 300. The low voltage DC power supply 200 includes EMI (Electromagnetic) Interference, electromagnetic interference) rectification filter circuit 201, isolated single-stage PFC (Power Factor Correction, power factor correction circuit 202 and rectification filter circuit 203, EMI rectification filter circuit 201 is connected to AC power supply AC, and rectification filter circuit 203 outputs low voltage DC power to overcurrent protection circuit 100. In other embodiments, the low voltage direct current may be provided by other existing means without limitation.

In addition, in the present embodiment, the load 300 is a DC-DC conversion circuit that receives the DC voltage DC converted by the low-voltage DC output output from the low-voltage DC power supply 200. In other embodiments, the load 300 may be other electrical circuits or devices, and is not limited thereto.

The overcurrent protection circuit 100 in the preferred embodiment of the present invention includes an overcurrent circuit breaker device 101, a current detecting module 102, a voltage dividing module 103, and a unidirectional thyristor D1.

The overcurrent circuit breaker member 101 has an overcurrent fuse function and is a fuse or a fuse. The input end of the overcurrent circuit breaker member 101 is connected to the output end of the low voltage DC power supply 200; the input end of the current detecting module 102 is connected to the output end of the flow interrupter device 101, and the output end of the current detecting module 102 is connected to the input end of the load 300, and current detection When the voltage drop of the module 102 exceeds the threshold, the trigger voltage is outputted at the trigger end; one end of the voltage dividing module 103 is connected to the trigger end of the current detecting module 102, and the other end of the voltage dividing module 103 is grounded; the anode current detecting of the unidirectional thyristor D1 is detected. At the input end of the module 102, the control terminal of the unidirectional thyristor D1 is connected to the trigger end of the current detecting module 102, and the cathode of the unidirectional thyristor D1 is grounded.

The current detecting module 102 includes a sampling resistor R1 and a PNP type transistor Q1. The first end of the sampling resistor R1 is connected as an input end of the current detecting module 102 to the output end of the current circuit breaker member 101, and is connected to the emitter of the transistor Q1; the sampling resistor R1 The second end serves as an input terminal for the output of the current detecting module 102 to the load 300, and is connected to the base of the transistor Q1. The collector of the transistor Q1 serves as a trigger end of the current detecting module 102. Preferably, the transistor Q1 is a small patch transistor of the SOT23 package.

Preferably, the voltage dividing module 103 includes a voltage dividing resistor R2 and a voltage stabilizing capacitor C1. One end of the voltage dividing resistor R2 is connected to the collector of the transistor Q1, and the other end is grounded, and the voltage stabilizing capacitor C1 is connected in parallel with the voltage dividing resistor R2. Preferably, the voltage dividing resistor R2 is a chip resistor. The voltage regulator capacitor C1 is a chip capacitor.

When the overcurrent protection circuit 100 fails due to the load 300, the current of the main circuit increases, and when the voltage drop across the current detection module 102 exceeds the threshold, a trigger voltage is generated to turn on the unidirectional thyristor D1, and the input of the load 300 is input. The terminal is shortly connected to the ground, and a large current is generated to melt the overcurrent circuit breaker member 101, and the power supply of the main circuit is cut off, thereby effectively protecting the electrical appliance and reducing the possibility of fire; the circuit device is less, the cost is low, and the utility is practical. high.

The above-mentioned embodiments are merely illustrative of several embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included. Within the scope of protection of the present invention.

Claims

An overcurrent protection circuit is connected between a low voltage DC power supply and a load, and is characterized by comprising:

The overcurrent circuit breaker component has an overcurrent fuse function, and the input end thereof is connected to the output end of the low voltage DC power source;

a current detecting module, the input terminal is connected to the output end of the overcurrent circuit breaker device, and the output terminal is connected to the input end of the load, and when the voltage drop of the current detecting module exceeds a threshold, the trigger voltage is output at the trigger end;

The voltage dividing module has one end connected to the trigger end of the current detecting module and the other end grounded;

The unidirectional thyristor has an anode connected to the input end of the current detecting module, a control pole connected to the trigger end of the current detecting module, and a cathode grounded.
The overcurrent protection circuit according to claim 1, wherein the current detecting module comprises a sampling resistor and a PNP type transistor, and the first end of the sampling resistor is connected to the overcurrent circuit breaker as an input terminal of the current detecting module. And an output terminal of the transistor; the second end of the sampling resistor serves as an input end of the current detecting module to the input end of the load, and is connected to a base of the transistor, the triode The collector is used as the trigger terminal of the current detecting module.
The overcurrent protection circuit according to claim 2, wherein the triode is a small patch transistor of the SOT23 package.
The overcurrent protection circuit according to claim 2 or 3, wherein the voltage dividing module comprises a voltage dividing resistor and a voltage stabilizing capacitor, wherein the voltage dividing resistor is connected to one end of the collector of the triode and the other end is grounded. The voltage stabilizing capacitor is connected in parallel with the voltage dividing resistor.
The overcurrent protection circuit according to claim 4, wherein said voltage dividing resistor is a chip resistor.
The overcurrent protection circuit according to claim 4, wherein the voltage stabilizing capacitor is a chip capacitor.
The overcurrent protection circuit according to claim 1, wherein said overcurrent circuit breaker member is a fuse or a fuse.
The overcurrent protection circuit according to claim 1, wherein the low voltage DC power supply comprises an EMI rectification filter circuit, an isolated single-stage PFC circuit and a rectification filter circuit, which are sequentially connected, and the EMI rectification filter circuit is connected to an AC power supply. The rectifying and filtering circuit outputs low voltage direct current.
The overcurrent protection circuit according to claim 1 or 8, wherein the load is a DC-DC conversion circuit.