CN102097922A

CN102097922A - Switching mode power supply and turn-off energy transfer method of power switching tube of switching mode power supply

Info

Publication number: CN102097922A
Application number: CN2010106012485A
Authority: CN
Inventors: 王际
Original assignee: SHENZHEN CITY DAYOUQING TECHNOLOGY Co Ltd
Priority date: 2010-12-22
Filing date: 2010-12-22
Publication date: 2011-06-15

Abstract

The invention provides a switching mode power supply and a turn-off energy transfer method of a power switching tube of the switching mode power supply, which are used for solving the problem of large loss of a power switching tube of an existing switching mode power supply. In the turn-off energy transfer method, a winding L2 is added at a primary side of a switching power transformer T1; a high voltage terminal of the winding L2, an output end of a winding L1 at a primary side of the switching power transformer T1 and a D end of a power switching tube K are connected together; a low voltage terminal of the winding L2 is connected with a capacitor C1; and the other end of the capacitor C1 is connected with a ground level of a circuit. According to the invention, the switching loss of the power switching tube can be greatly reduced, blockage resulting from high energy consumption of the power switching tube in the development process of the switching mode power supply can be eliminated, the conversion efficiency of the whole switching mode power supply can be improved, the cost is saved, and the volume of the whole switching mode power supply can be decreased.

Description

The shutoff energy transfer method and the Switching Power Supply of the power switch pipe of Switching Power Supply

Technical field

The present invention relates to Switching Power Supply, relate in particular to a kind of shutoff energy transfer method and a kind of Switching Power Supply of power switch pipe of Switching Power Supply.

Background technology

Because the clear superiority of Switching Power Supply in electrical property and energy-conserving and environment-protective, in growing field for example: communication, means of transportation, military affairs, instrument and meter, industrial equipment, household electrical appliance etc. have all obtained application more and more widely.We can say at present so long as the equipment of electricity consumption all needs Switching Power Supply.

The advantage of Switching Power Supply is small size, high efficiency, high reliability.Can developing direction focus on and satisfying:

1, satisfies the Electro Magnetic Compatibility standard comprehensively.

2, steady production on a large scale.

3, more miniaturization.

In the development process of Switching Power Supply, how to reduce power switch pipe electric stress and when work power switch pipe autophage power be more and more distinct issues.

Traditional solution has following two kinds.

First kind is the circuit that reduces switch stress.

Referring to Fig. 1, Fig. 2 and Fig. 3, the operation principle of the buffer network shown in the frame of broken lines in the circuit diagram outside the transformer T1: when t2, be engraved in switch transistor T r and turn-off, when Vc rises to above Vs, diode D1 conducting, capacitor C 1 charging, Vc rises to Vc2, and resistance R 1 bleeds off the charging charge of capacitor C 1 in the time that diode D1 turn-offs.If there is not buffer network, t2 voltage constantly can reach Vc1.Too high Vc voltage may surpass the tolerance range of power switch pipe Tr, causes this device failure.Can see that buffer network is the peak that reduces Vc in catabiotic mode.

Second kind is soft switch technique.

In the Switching Power Supply, the loss power of power switch pipe is divided into switching loss and conduction loss, and wherein switching loss accounts for major part.Along with improving constantly of switching frequency, the loss power of power switch pipe is more and more higher, and the switching loss proportion also improves constantly, and the miniaturization of Switching Power Supply is brought increasing obstruction.In order to address this problem, soft switch technique has appearred.

Fig. 4 is a very circuit of the soft switch implementation method of employing of standard:

Referring to Fig. 4 and Fig. 5, at t2 constantly, switching tube S turn-offs, and the former limit inductance of transformer T1 and capacitor C 1 form resonance, and the Vc rising waveform slows down, and the loss when power switch tube S is turn-offed reduces.But need to prove: the energy that is stored in when power switch tube S is turn-offed on the capacitor C 1 can consume on power switch tube S when switching tube S opens.

Summary of the invention

The objective of the invention is to exist above deficiency respectively the shutoff energy transfer method of the power switch pipe of the Switching Power Supply that provide a kind of switching loss that can reduce power switch pipe, reduces cost and use a kind of Switching Power Supply of this method at existing traditional Switching Power Supply.

The shutoff energy transfer method of the power switch pipe of Switching Power Supply of the present invention, be to increase a winding L 2 on the former limit of switch transformer T1, the output of the former limit winding L 1 of the high-pressure side of winding L 2 and switch transformer T1 and the D of power switch pipe K end link together, the low-pressure end of winding L 2 is connected with capacitor C 1, the ground level of the other end connection circuit of capacitor C 1.

Switching Power Supply of the present invention, comprise a switch transformer T1, a power switch pipe K, a capacitor C 1, the input termination input voltage of the former limit winding L 1 of described switch transformer T1, the D end of output termination power switch pipe K, the ground level of the S termination circuit of power switch pipe K, the G termination pulse-width modulation waveform drive level of power switch pipe K, former limit at described switch transformer T1 increases a winding L 2, the output of the former limit winding L 1 of the high-pressure side of winding L 2 and switch transformer T1 and the D of power switch pipe K end link together, the low-pressure end of winding L 2 is connected with capacitor C 1, the ground level of the other end connection circuit of capacitor C 1.

Referring to Fig. 6 and Fig. 7, principle of the present invention and technique effect are as follows:

1, because the effect of winding L 2 and capacitor C 1 is turn-offed the t2 time at power switch pipe K, and the trailing edge of Vg and the rising edge of Vc do not overlap fully, so the turn-off power loss of power switch pipe K is zero.

2, in the t1 time that power switch pipe K opens, the energy storage of capacitor C 1 feeds back to switch transformer T1 by winding L 2 fully, can not form extra turn-on consumption.

Because above two characteristics, the present invention can reduce the switching loss of power switch pipe K significantly, thereby solves the obstruction that the power switch pipe high energy consumption is brought in the Switching Power Supply evolution.Can also improve the conversion efficiency of whole Switching Power Supply.

3, owing to the effect of winding L 2 and capacitor C 1, can effectively reduce the ceiling voltage of Vc, replace the effect of traditional buffer network fully.Adopt method of the present invention can save buffer network, save cost and the volume that reduces whole Switching Power Supply.

4, adopt method of the present invention, make the rising waveform of Vc significantly slow down, significantly reduce the electromagnetic interference of whole switching power circuit, can satisfy the Electro Magnetic Compatibility standard with littler cost.

Description of drawings

Fig. 1, Fig. 2 are existing two kinds of circuit theory diagrams that reduce the Switching Power Supply of switch stress.

Fig. 3 is the time plot of Vc point voltage in the circuit of Fig. 1 and Fig. 2.

Fig. 4 is the circuit theory diagrams that adopt the Switching Power Supply of soft switch technique.

Fig. 5 is the time plot of Vc point voltage in Fig. 4 circuit.

The circuit theory diagrams of Fig. 6 embodiment of the invention.

Fig. 7 is the time plot of Vc point voltage in Fig. 6 circuit.

Embodiment

Referring to Fig. 6, the Switching Power Supply of present embodiment comprises a switch transformer T1, a power switch pipe K, a capacitor C 1, the input 1 of the former limit winding L 1 of described switch transformer T1 connects input voltage, the output 2 of winding L 1 connects the D end of power switch pipe K, the ground level of the S termination circuit of power switch pipe K, the G termination pulse-width modulation waveform drive level Vg of power switch pipe K, the difference of present embodiment and prior art is to increase a winding L 2 on the former limit of switch transformer T1, the high-pressure side 3 of winding L 2 links together with the D end of the output 2 of the former limit winding L 1 of switch transformer T1 and power switch pipe K, the low-pressure end 4 of winding L 2 is connected with capacitor C 1, the ground level of the other end connection circuit of capacitor C 1.

Circuit shown in Figure 6 has embodied the shutoff energy transfer method of the power switch pipe of Switching Power Supply of the present invention fully.

Referring to Fig. 6 and Fig. 7, the operation principle of present embodiment is as follows:

1, constantly, power switch pipe K turn-offs, and the electric current that flow through power switch pipe K originally charges to capacitor C 1 by winding L 2, and Vc voltage slowly rises at t2.

2, constantly, power switch pipe K opens, and electric energy stored is via winding L 2 and power switch pipe K discharge on the capacitor C 1, and its electric energy becomes magnetic energy and feeds back to switch transformer T1 owing to the effect of winding L 2 at t1.

Claims

1. the shutoff energy transfer method of the power switch pipe of a Switching Power Supply, it is characterized in that: the former limit at switch transformer T1 increases a winding L 2, the output of the former limit winding L 1 of the high-pressure side of winding L 2 and switch transformer T1 and the D of power switch pipe K end link together, the low-pressure end of winding L 2 is connected with capacitor C 1, the ground level of the other end connection circuit of capacitor C 1.

2. Switching Power Supply, comprise a switch transformer T1, a power switch pipe K, a capacitor C 1, the input termination input voltage of the former limit winding L 1 of described switch transformer T1, the D end of output termination power switch pipe K, the ground level of the S termination circuit of power switch pipe K, the G termination pulse-width modulation waveform drive level of power switch pipe K, it is characterized in that: the former limit at described switch transformer T1 increases a winding L 2, the output of the former limit winding L 1 of the high-pressure side of winding L 2 and switch transformer T1 and the D of power switch pipe K end link together, the low-pressure end of winding L 2 is connected with capacitor C 1, the ground level of the other end connection circuit of capacitor C 1.