CN201365201Y

CN201365201Y - Input rectifying and filtering circuit of switch power supply

Info

Publication number: CN201365201Y
Application number: CNU2009201059420U
Authority: CN
Inventors: 饶科
Original assignee: BEIJING NORTHGLASS SAFETY GLASS Co Ltd; Luoyang North Glass Technology Co Ltd; Shanghai North Glass Coating Technology Industry Co Ltd
Current assignee: Shanghai North Glass Technology and Industry Co Ltd
Priority date: 2009-02-19
Filing date: 2009-02-19
Publication date: 2009-12-16
Anticipated expiration: 2019-02-19

Abstract

The utility model discloses an input rectifying and filtering circuit of a switch power supply, which comprises a rectifying unit and a filtering unit. The input rectifying and filtering circuit further comprises a protecting unit. The protecting unit comprises a current-limiting subunit and a control subunit; one end of the current-limiting subunit is connected with the output end of the rectifying unit, the other end of the current-limiting subunit is connected with one end of the filtering unit, and the current-limiting subunit is used for limiting current flowing through the filtering unit; the control subunit which is connected with the current-limiting subunit in parallel is used for short-circuiting the current-limiting subunit when voltage at the two ends of the filtering unit is larger than the preset value; one end of the filtering unit is connected with the current-limiting subunit, and the other end is connected with the input end of the rectifying unit. The input rectifying and filtering circuit can limit surge current generated by the rectifying and filtering part of the input circuit of the switch power supply, so as to protect normal running of the switch power supply.

Description

A kind of input rectifying filter circuit of Switching Power Supply

Technical field

The utility model relates to a kind of current rectifying and wave filtering circuit, relates in particular to a kind of input rectifying filter circuit of Switching Power Supply.

Background technology

At present, as shown in Figure 1, the rectification of the input circuit of Switching Power Supply commonly used on the market, filtering part mostly adopt capacitor filtering type rectification circuit, close a floodgate moment at incoming power, because the initial voltage on the capacitor is zero, moment in the capacitor charging can form very big surge current, like this, the lighter can make air switch close not brake application, weight person tends to cause importing that fuse blows or the burning of contact of combined floodgate switch, the rectifier bridge overcurrent damages, even can cause the high frequency transformer magnetic core saturated and damage power device.

Summary of the invention

Main purpose of the present utility model is to provide a kind of input rectifying filter circuit of Switching Power Supply, the surge current that the rectifying and wave-filtering of input circuit that can the limit switch power supply partly produces, the normal operation of protection switch power supply.

In order to achieve the above object, the utility model provides Switching Power Supply input rectifying filter circuit, and it comprises rectification unit and filter unit, and it also comprises protected location, and described protected location comprises current limliting subelement and control sub unit;

Described current limliting subelement, the output of the described rectification unit of one end connects, and an end of its other end and described filter unit is connected, and is used for limiting the electric current of described filter unit of flowing through;

Described control sub unit, in parallel with described current limliting subelement, when being used for voltage when described filter unit two ends, with the short circuit of described current limliting subelement greater than predetermined value;

Described filter unit, the one end is connected with described current limliting subelement, and its other end is connected with the input of described rectification unit.

Preferably, described control sub unit comprises switch module and SCR control module, wherein:

Described switch module, in parallel with described current limliting subelement; When described switch module conducting, with the short circuit of described current limliting subelement;

Described SCR control module is connected with the control end of described switch module, with conducting and the disconnection of controlling described switch module.

Preferably, described filter unit is electric capacity (C5);

Described switch module is controllable silicon unit (Q1);

Described SCR control module comprises resistance (R2) and is installed on the ancillary coil of a transformer (T1) primary side;

Described resistance (R2) is series between the free end of ancillary coil of the control end of described controllable silicon unit (Q1) and described transformer (T1);

The primary coil of described transformer (T1) is connected with the end of the common port of ancillary coil with described electric capacity (C5); The free end of the primary coil of described transformer is connected with the collector electrode of a transistor (Q2), and described transistor (Q2) is connected with the other end of described electric capacity (C5);

Direct current after described rectification unit rectification charges to described electric capacity (C5) through described current limliting unit, when the voltage at described electric capacity (C5) two ends reaches a predetermined value, described transistor Q2 conducting, the primary coil of described transformer (T1) is started working, the secondary coil two ends of described transformer (T1) have produced voltage, the corresponding generation voltage in the two ends of the ancillary coil of described transformer (T1) makes and described controllable silicon unit (Q1) conducting has realized the short circuit with current-limiting resistance R1.

Compared with prior art; the input rectifying filter circuit of Switching Power Supply described in the utility model; adopted protected location; described protected location comprises current limliting subelement and control sub unit; described current limliting subelement can the limit switch power supply the surge current that partly produces of the rectifying and wave-filtering of input circuit, described control sub unit can make after voltage is stable that Switching Power Supply keeps normal operation.

Description of drawings

Fig. 1 is the circuit diagram of the input rectifying filter circuit of existing Switching Power Supply;

Fig. 2 is the circuit block diagram of a kind of concrete enforcement of input rectifying filter circuit of Switching Power Supply described in the utility model;

Fig. 3 is the another kind of concrete circuit diagram of implementing of the input rectifying filter circuit of Switching Power Supply described in the utility model.

Embodiment

Below in conjunction with accompanying drawing, be described in more detail with other technical characterictic and advantage the utility model is above-mentioned.

In order to overcome the defective of prior art; this case inventor has designed a kind of Switching Power Supply input rectifying filter circuit that can limit inrush currents; adopted protected location; described protected location comprises current limliting subelement and control sub unit; described current limliting subelement can limit rectification unit and export electric current in the filter unit to; described control sub unit can be moved thereby make Switching Power Supply keep normal with the short circuit of described current limliting subelement after voltage is stable.

As shown in Figure 2, Switching Power Supply input rectifying filter circuit described in the utility model comprises rectification unit 1, protected location 2 and filter unit 3, and described protected location 2 comprises current limliting subelement 21 and control sub unit 22, wherein:

Described rectification unit 1 is used for alternating current is converted to direct current;

Described current limliting subelement 21, the output of the described rectification unit 1 of one end connects, and its other end is connected with an end of described filter unit 3, is used for limiting the electric current of described filter unit 3;

Described control sub unit 22, in parallel with described current limliting subelement 21, when being used for voltage when described filter unit 3 two ends, with described current limliting subelement 21 short circuits greater than predetermined value;

Described filter unit 3, the one end is connected with described limit stream unit 21, and its other end is connected with the input of described rectification unit 1, is used for the direct current of described rectification unit 21 outputs is carried out filtering.

Preferably, described control sub unit 22 comprises switch module and SCR control module, wherein:

Described switch module, in parallel with described current limliting subelement 21; When described switch module conducting, with described current limliting subelement 21 short circuits;

Described SCR control module is connected with the control end of described switch module 221, with conducting and the disconnection of controlling described switch module.

As shown in Figure 3, according to a kind of preferred embodiment, described rectification unit 1 is rectifier bridge (D1-D4), and described current limliting subelement 21 is current-limiting resistance R1, described filter unit 3 is capacitor C 5, and the switch module of described control sub unit 22 is controllable silicon unit Q1;

The SCR control module of described control sub unit 22 comprises resistance R 2 and the ancillary coil that is installed on the primary side of a transformer T1, wherein:

The coil of the upper left of described transformer T1 is called ancillary coil, and the coil of the bottom left section of described transformer T1 is called primary coil, and the coil of the right-hand member of described transformer T1 is called secondary coil;

Described resistance R 2 is series between the free end of ancillary coil of the control end of described controllable silicon unit Q1 and described transformer T1;

The primary coil of described transformer T1 is connected with an end of capacitor C 5 with the common port of ancillary coil; The free end of the primary coil of described transformer T1 is connected with the collector electrode of transistor Q2, and the emitter of described transistor Q2 is connected with the other end of described capacitor C 5;

Be connected in series one drive circuit between the base stage of described transistor Q2 and the emitter, described drive circuit sends pwm signal to described transistor Q2, to drive described transistor Q2;

The two ends of the secondary coil of described transformer T1 are connected with the LC filter circuit of being made up of diode D1, diode D2, inductor L2 and capacitor C 6;

Direct current after rectifier bridge (D1-D4) rectification charges to capacitor C 5 through current-limiting resistance R1, when the voltage at described capacitor C 5 two ends reaches a predetermined value (described predetermined value can be rated voltage 80%), described transistor Q2 conducting, the primary coil of transformer T1 is started working, then the secondary coil two ends of transformer T1 have produced voltage, the also corresponding generation voltage in the two ends of the ancillary coil of transformer T1, make the Q1 conducting of described controllable silicon unit, realized the short circuit with current-limiting resistance R1, after this Switching Power Supply is in normal operating state.

More than explanation is just illustrative for the utility model; and it is nonrestrictive; those of ordinary skills understand; under the situation of the spirit and scope that do not break away from following claims and limited; can make many modifications; change, or equivalence, but all will fall in the protection range of the present utility model.

Claims

1, a kind of Switching Power Supply input rectifying filter circuit, it comprises rectification unit and filter unit, it is characterized in that, and it also comprises protected location, and described protected location comprises current limliting subelement and control sub unit;

2, Switching Power Supply input rectifying filter circuit as claimed in claim 1 is characterized in that, described control sub unit comprises switch module and SCR control module, wherein:

3, Switching Power Supply input rectifying filter circuit as claimed in claim 2 is characterized in that,

Described filter unit is electric capacity (C5);

Described switch module is controllable silicon unit (Q1);