CN100438598C

CN100438598C - Reverse-excitation power supply

Info

Publication number: CN100438598C
Application number: CNB2006100345214A
Authority: CN
Inventors: 戴奇峰; 高博
Original assignee: Shenzhen Skyworth RGB Electronics Co Ltd
Current assignee: Shenzhen Skyworth RGB Electronics Co Ltd
Priority date: 2006-03-17
Filing date: 2006-03-17
Publication date: 2008-11-26
Anticipated expiration: 2026-03-17
Also published as: CN1893594A

Abstract

Inverse excitation type power supply includes two transformers, voltage regulator tubes and capacitor. Positive pole of output end of each transformer is connected to a parallel circuit composed of two voltage regulator tubes and one capacitor. Main windings of two transformers are connected in series, and secondary windings of two transformers are connected in parallel. The said structure lowers own temperature of voltage regulator tubes and transformers, raises efficiency and reliability of power supply, and provides higher output power. The disclosed power supply is applicable to liquid crystal TV in large size.

Description

A kind of flyback power supply

Technical field

The present invention relates to the flyback power supply that a kind of energy uses for the large scale liquid crystal TV.

Background technology

After LCD TV occurs because the increasing of the demand in market and the development of technology, the power supply of LCD TV from before external power supply develop into present built-in power.Because volume structure, it is very little that the size of power supply can only be done.Therefore with regard to many problems having occurred, all new requirement has been proposed power supply such as height, heat radiation, power capacity, efficient etc.

The power supply of television set develops into various topological structures such as present inverse-excitation type, positive activation type, half-bridge, full-bridge, active clamp from the auto-excitation type power supply that the earliest CRT uses.Though the topological structure of power supply is more and more, efficient is also more and more higher, and temperature rise is also more and more lower, and they all have certain limitation and shortcoming: flyback power supply is because the influence of transformer can only be accomplished 200W generally speaking; The output of forward power need connect an accumulation of energy inductance, so just causes the weight of power panel to increase, and the anti-seismic performance of power supply also is under some influence; Though half-bridge or full-bridge type power supply are the up-to-date topological structures that occurred in recent years, because its leakage inductance is difficult to control, so produce the comparison difficulty; Active clamp formula power supply is because be external patented technology, so use relatively more expensive in price.

The topological structure of flyback power supply is fairly simple, and cost is also low, so many producers still are as topological structure commonly used it.Flyback power supply is gone up to use at the TV (CRT) in modern times and is got more and more, but its efficient is lower; If adopt the quasi-resonance structure, though its efficient increases, it also is subjected to the puzzlement of temperature rise, power; Problems such as the temperature rise of flyback power supply, efficient, power output have become the problem that manufacturer all relatively pays close attention to.The power output of flyback power supply, under situation not with PFC, the maximum power that the magnetic core of a PQ3230 can be accomplished is only about 120W, and at most also can only accomplish about 180W under the situation of band PFC, and present 32 cun liquid crystal television power supply mostly need be about 230W, so present flyback power supply can not provide reliable power supply for large-sized LCD TV.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of efficient and power output all than flyback power supply higher, that can use for the large scale liquid crystal TV.

The technical scheme that the present invention solves the problems of the technologies described above employing is: a kind of flyback power supply, comprise first transformer, second transformer, first voltage-stabiliser tube, second voltage-stabiliser tube, the 3rd voltage-stabiliser tube, the 4th voltage-stabiliser tube, first capacitor and second capacitor, it is characterized in that: be respectively equipped with the opposite main winding of both direction on described first transformer and second transformer, the main winding series connection of described first transformer and second transformer, wherein the positive contact of two windings of first winding negative contacts of second transformer and first transformer is connected with external power source respectively, the negative contacts of second winding of the positive contact of first winding of second transformer and first transformer is connected with ground wire, be connected another output of external power source behind the positive contact difference series resistor of second winding of described first transformer and second transformer, the negative contacts of second winding of second transformer is connected with the negative contacts of first winding of first transformer; The auxiliary winding parallel connection of described first transformer and second transformer, the positive pole of the output of the described second transformer auxiliary winding is connected with first voltage-stabiliser tube, second voltage-stabiliser tube and first capacitor in parallel, the positive pole of described first voltage-stabiliser tube and second voltage-stabiliser tube is connected with the positive pole of the output of the described second transformer auxiliary winding, and the negative pole of described first voltage-stabiliser tube and second voltage-stabiliser tube forms the output of flyback power supply; The positive pole of the output of the described first transformer auxiliary winding is connected with the 3rd voltage-stabiliser tube, the 4th voltage-stabiliser tube and second capacitor in parallel, the positive pole of described the 3rd voltage-stabiliser tube and the 4th voltage-stabiliser tube is connected with the positive pole of the output of the described first transformer auxiliary winding, and the negative pole of described the 3rd voltage-stabiliser tube and the 4th voltage-stabiliser tube forms the output of flyback power supply and is connected with the negative pole of described first voltage-stabiliser tube; The cathode output end of described first transformer and second transformer is connected back connecting to neutral line.

The leakage inductance of described first transformer and second transformer should be the 1%-3% of primary electrical sensibility reciprocal, and too big leakage inductance will increase the consume of circuit.

The number of turn of described first transformer and the second transformer main winding reduces, and the width of winding increases, and makes the number of turn of each layer be paved with whole skeleton; Insulating barrier between each winding reduces; Coupling degree between the winding increases, thereby realizes reducing of transformer leakage inductance.

The technological progress that the present invention obtains is: adopt this spline structure to reduce the temperature of switching tube and transformer self, improved the efficient and the reliability of power supply.Select for use the little Xiao Te pipe diode of VF value that the loss on diode is diminished, can further improve the efficient and the reliability of power supply.The leakage inductance of power supply has only the 1%-3% of primary electrical sensibility reciprocal, so the peak voltage that it produced is very little, and the loss of drain electrode clamp circuit is also just considerably less, helps the raising of efficient like this.The present invention has carried out application test on the LCD power supply, maximal efficiency has reached 89%, and temperature is also low than like product.The circuit of synchronous rectification rectifier system that the present invention adopts can further promote the efficient of power supply, makes it can reach about 91%, more advanced than former circuit, bigger advantage is arranged, but cost can be changed when doing multichannel output also than higher with DC-DC.

Description of drawings

Fig. 1 is a circuit structure diagram of the present invention.

Embodiment

Below in conjunction with accompanying drawing the present invention is done further detailed description.

As seen from the figure: the present invention includes the first transformer T3, the second transformer T4, the first voltage-stabiliser tube D11, the second voltage-stabiliser tube D12, the 3rd voltage-stabiliser tube D13, the 4th voltage-stabiliser tube D14, the first capacitor C33 and the second capacitor C39, two transformer T3, be respectively equipped with two on the T4 and revolve the rich opposite main winding of direction, the positive contact 3 of two windings of first winding negative contacts 1 of the second transformer T4 and the first transformer T3 wherein, 6 are connected with external power source respectively, the positive contact 3 of first winding of the second transformer T4 is connected with ground wire with the negative contacts 5 of second winding of the first transformer T3, two transformer T3, another output that connects external power source behind the positive contact 6 difference series resistor R19 of second winding of T4, the negative contacts 5 of second winding of the second transformer T4 is connected with the negative contacts 1 of first winding of the first transformer T3, such two transformer T3, the main winding of T4 forms the mode of series connection; Positive pole at the auxiliary winding output of each transformer is connected with two voltage-stabiliser tubes and an electric capacity in parallel, an end points 3 after voltage-stabiliser tube and the electric capacity parallel connection is connected on the positive pole 11 of auxiliary winding of two transformer T3, T4, another end points 2 forms an output, the cathode output end 9 of two transformer T3, T4 connects back connecting to neutral line, and the auxiliary winding of such two transformer T3, T4 forms connected mode in parallel.

The leakage inductance of the above-mentioned first transformer T3 and the second transformer T4 is the 1%-3% of primary electrical sensibility reciprocal.Taked the number of turn of following measure: a, the minimizing first transformer T3 and the elementary winding of the second transformer T4 for the leakage inductance the present invention who reduces the first transformer T3 and the second transformer T4, the width of b, increase winding, just make the number of turn of each layer be paved with whole skeleton, insulating barrier between c, the minimizing winding, the coupling degree between d, the increase winding.

Select for use the VF value little when selecting Xiao Te pipe diode for use, the loss on diode will be smaller so as far as possible.

Also has a kind of method that can promote efficient for flyback power supply, that carries out synchronous rectification with circuit of synchronous rectification exactly, the efficient of power supply can be brought up to about 91% like this, can change with DC-DC when doing multichannel output, and the shortcoming of this structure is that cost is than higher.

Claims

1, a kind of flyback power supply, comprise first transformer (T3), second transformer (T4), first voltage-stabiliser tube (D11), second voltage-stabiliser tube (D12), the 3rd voltage-stabiliser tube (D13), the 4th voltage-stabiliser tube (D14), first capacitor (C33) and second capacitor (C39), it is characterized in that: be respectively equipped with the opposite main winding of both direction on described first transformer (T3) and second transformer (T4), the main winding series connection of described first transformer (T3) and second transformer (T4), the positive contact (3 of two windings of first winding negative contacts (1) of second transformer (T4) and first transformer (T3) wherein, 6) be connected with external power source respectively, the positive contact (3) of first winding of second transformer (T4) is connected with ground wire with the negative contacts (5) of second winding of first transformer (T3), positive contact (6) difference series resistor (R19) back of described first transformer (T3) and second winding of second transformer (T4) is connected another output of external power source, and the negative contacts (5) of second winding of second transformer (T4) is connected with the negative contacts (1) of first winding of first transformer (T3); The auxiliary winding parallel connection of described first transformer (T3) and second transformer (T4), the positive pole of the output of described second transformer (T4) auxiliary winding is connected with first voltage-stabiliser tube (D11), second voltage-stabiliser tube (D12) and first capacitor (C33) in parallel, the positive pole of described first voltage-stabiliser tube (D11) and second voltage-stabiliser tube (D12) is connected with the positive pole of the output of described second transformer (T4) auxiliary winding, and the negative pole of described first voltage-stabiliser tube (D11) and second voltage-stabiliser tube (D12) forms the output of flyback power supply; The positive pole of the output of described first transformer (T3) auxiliary winding is connected with the 3rd voltage-stabiliser tube (D13), the 4th voltage-stabiliser tube (D14) and second capacitor (C39) in parallel, the positive pole of described the 3rd voltage-stabiliser tube (D13) and the 4th voltage-stabiliser tube (D14) is connected with the positive pole of the output of described first transformer (T3) auxiliary winding, and the negative pole of described the 3rd voltage-stabiliser tube (D13) and the 4th voltage-stabiliser tube (D14) forms the output of flyback power supply and is connected with the negative pole of described first voltage-stabiliser tube (D11); The cathode output end (9) of described first transformer (T3) and second transformer (T4) is connected back connecting to neutral line.

2, a kind of flyback power supply according to claim 1 is characterized in that: the leakage inductance of described first transformer (T3) and second transformer (T4) is the 1%-3% of primary electrical sensibility reciprocal.

3, a kind of flyback power supply according to claim 1 and 2, the number of turn that it is characterized in that described first transformer (T3) and second transformer (T4) main winding reduces, the width of winding increases, make the number of turn of each layer be paved with whole skeleton, insulating barrier between each winding reduces, and the coupling degree between the winding increases.