CN203219182U - Self-excited push-pull converter - Google Patents

Abstract

The utility model discloses a self-excited push-pull converter. A capacitor is additionally arranged between collector electrodes of two push-pull triodes to control frequency and continuous time of high frequency oscillation during electrification. A RongLing magnetic core capable of locally magnetic saturation is employed, so that the self-excited push-pull converter is faster in staring and higher in transformation efficiency, has good starting performance at low temperature, and also has good protection function against short circuit.

Description

A kind of self-excitation push-pull converter

Technical field

The utility model relates to the power module that adopts self-excitation push-pull converter topology.

Background technology

Existing self-excitation push-pull converter, circuit structure is from the self-oscillation push-pull transistor single phase transformer DC converter of nineteen fifty-five U.S. Luo Ye (G.H.Royer) invention, also make the Royer circuit, this also is the beginning of realizing the high frequency conversion control circuit, the related work principle of self-excitation push-pull converter has description in " principle of Switching Power Supply and the design " the 67th page to 70 pages of Electronic Industry Press, this book ISBN 7-121-00211-6.The principal mode of circuit is above-mentioned famous Royer circuit.

Shown in Fig. 1 is the common application of self-excitation push-pull converter, circuit structure is the Royer circuit, in Fig. 1, circuit all will utilize the magnetic core saturation characteristic of transformer B1 to vibrate, its operation principle has description for the 70th page in above-mentioned " principle of Switching Power Supply and design ", the circuit form of self-excitation push-pull converter and operation principle thereof, at Chinese Granted publication numbers 102082526, Chinese application number 201110200894,201110242377,201110272261,201110436259,201210056583,201220206952,201220207489 and 201210174076 all descriptions on the books and detailed.Particularly application number is 201110436259 patent application, by the innovation to the transformer in the self-excitation push-pull converter, the triggering signal that a local magnetic saturation zone provides self-excitation to recommend is set, reduce the loss that causes because of magnetic saturation, promoted operating efficiency, frequency, but still there is the higher-order of oscillation in this converter when powering on, start-up time is longer, referring to start-up time power on from operating voltage picks up counting, and to converter voltage output output rated voltage 95% o'clock stops timing.The typical case that Fig. 2 shows application number 201110436259 invention uses, and Fig. 2 is from the peripheral patent application of this invention, and application number is the accompanying drawing 10 in 201220206952 the open file.The used magnetic core of transformer B1 is a kind of of Rong Ling magnetic core among Fig. 2, in the background technology in the Chinese application number 201220206952 that the definition of Rong Ling magnetic core is mentioned referring to background technology, the 201220207489 two parts of files last two sections.For clearer explanation the technical solution of the utility model, below disclosed this Rong Ling magnetic core in the prior art to be made an explanation, this special magnetic core is found in two Chinese invention patent ublic specification of application, is respectively:

Application number: in 201110436359 " a kind of magnetic core for transformer "; A kind of magnetic core for transformer, it is characterized in that: described magnetic core is made up of thick portion and the thin portion of closure, described thin portion reaches magnetic saturation earlier than described thick portion under identical ascending magnetic field excitation, described thin portion is when work, only approach or reach described thin portion first quartile saturation point or third quadrant saturation point in moment, At All Other Times all between described thin portion intrinsic first quartile saturation point and third quadrant saturation point;

And application number: in 201110436259 " a kind of self-excitation push-pull converter ", the closed core of described transformer or unshakable in one's determination by principal part and local the composition, described part reaches magnetic saturation earlier than described principal part under identical ascending magnetic field excitation.

In fact, above-mentioned two disclosed closed cores of patent application are identical with magnetic core for transformer in essence, and because in actual production, these two kinds of magnetic cores are the defending party to the application and inventor's called after " Rong Ling magnetic core " or " Rong Ling magnetic core ", so in this article, for convenient narration technical scheme, for this special magnetic core that meets definition, be referred to as: the Rong Ling magnetic core.

And in the invention of Chinese Granted publication numbers 102082526, put down in writing a kind of self-excitation push-pull converter, comprise the input soft starting circuit that connects successively, the bipolarity push-pull circuit, coupling transformer, output filter circuit, described bipolarity push-pull circuit comprises two triodes of recommending annexation, the emitter of two triodes altogether, the base stage of two triodes connects the feedback winding two ends of coupling transformer respectively, the collector electrode of two triodes connects the winding two ends, former limit of coupling transformer respectively, it is characterized in that also comprising that described high-frequency self-excitation suppresses circuit and is connected in the described bipolar push-pull circuit for eliminating described triode produces pure oscillation because characteristic frequency is too high when powering on the high-frequency self-excitation inhibition circuit of recommending.Set forth for convenience, here quoted the accompanying drawing circuit of first embodiment in the authority of Granted publication numbers 102082526 as Fig. 3 of present specification, for convenience this paper claim is described, and unique resistance R 2 in the original text changed into element sequence number R1 in the present specification.Coupling transformer is also made transformer at above-mentioned other application documents.

In actual use, Fig. 3 circuit has improved DC-AC really or DC-DC converter output voltage when powering on is low, and the output voltage rising is problem too slowly; After adopting this circuit, high-frequency self-excitation when powering on is attenuated oscillation or frequency of oscillation moves down, circuit just can be in tens cycles, enter very soon and utilize in the push-pull oscillator that the magnetic core saturation characteristic carries out, realize the quick startup of circuit, allow DC-AC or DC-DC converter in 10mS even shorter time, reach rated output voltage.

But Fig. 3 circuit is the high conversion efficiency as Fig. 2 circuit not, and the self-excitation push-pull converter of Fig. 2 and Fig. 3 does not all have the output short circuit protection function.

Summary of the invention

The purpose of this utility model provides a kind of self-excitation push-pull converter, can overcome the shortcoming that existing self-excitation push-pull converter exists, and start-up time is faster, the conversion efficiency height, and good short-circuit protection function is arranged.

The purpose of this utility model is achieved through the following technical measures:

A kind of self-excitation push-pull converter comprises input filter capacitor, biasing circuit, recommends two triodes, transformer and output filter circuits of usefulness; Being characterized as of self-excitation push-pull converter: the magnetic core of described transformer is the Rong Ling magnetic core, and biasing circuit comprises first resistance and first electric capacity at least, recommends to connect second electric capacity between two transistor collectors of usefulness.

As the further optimization of technique scheme, described self-excitation push-pull converter obtains the method for short-circuit protection function, and the short-circuit protection method of described self-excitation push-pull converter may further comprise the steps:

Steps A: with the output short circuit of self-excitation push-pull converter, regulate the leakage inductance of main power transformer in the self-excitation push-pull converter, make the short circuit current protection of self-excitation push-pull converter greater than the short-circuit protection limiting current;

Step B: regulate the capacity of second electric capacity, make described steps A regulate the short circuit current protection that obtains and drop to minimum value;

Step C: increase the capacitance of first electric capacity in the self-excitation push-pull converter, make the self-excitation push-pull converter enter clearance-type higher-order of oscillation state and short circuit current protection is reduced to below the short-circuit protection limiting current;

Step D: the output short-circuit condition of eliminating the self-excitation push-pull converter.

As further improvement in the technical proposal, substitute the first above-mentioned resistance with constant-current source and provide biasing to circuit.

Operation principle of the present utility model:

The operation principle of the second above-mentioned electric capacity please refer to the relative theory of Chinese Granted publication numbers 102082526, second electric capacity and get on after, the distributed capacitance of circuit and the transformer distributed capacitance under high frequency seems by contrast and can ignore, high-frequency self-excitation frequency of oscillation when powering on moves down, and is displaced downwardly to the characteristic frequency f of two triodes of recommending usefulness _TBelow 1/3rd.

After high-frequency self-excitation was attenuated or frequency of oscillation moves down, described two triodes of recommending usefulness just can be in tens cycles, entered very soon to utilize in the push-pull oscillator that the magnetic core saturation characteristic carries out, and realized the quick startup of circuit.

Owing to used the Rong Ling magnetic core, conversion efficiency of the present utility model has tangible lifting, and this is owing to be provided with the triggering signal that a local magnetic saturation zone provides self-excitation to recommend, and reduces the loss that causes because of magnetic saturation, has promoted operating efficiency, operating frequency;

Because the adding of second electric capacity, make the debugging of short-circuit protection function of the present utility model become and be easy to that the principle of this part is referring to " a kind of short-circuit protection method of self-excitation push-pull converter " literary composition of Chinese application number 201210174076.

Compared with prior art, the utlity model has following significant effect:

Almost do not increasing under the components and parts situation, realizing that the self-excitation push-pull converter is faster start-up time, still having good startability at low temperatures, conversion efficiency is higher, and good short-circuit protection function is arranged.

Description of drawings

Fig. 1 is the common application circuit of self-excitation push-pull converter Royer circuit;

Fig. 2 is that the typical case of Rong Ling magnetic core uses, and comes from the accompanying drawing 10 in the open file of application number 201220206952;

Fig. 3 is the circuit diagram of the first embodiment correspondence in Chinese Granted publication number 102082526 patent documentations;

Fig. 4 is the schematic diagram of embodiment one;

Fig. 5 is the schematic diagram of embodiment two;

Fig. 6 is the schematic diagram of embodiment three.

Embodiment

Embodiment one

Embodiment one adopts the circuit theory diagrams of Fig. 4, comprise transformer B1, its annexation is: input filter capacitor C is connected between operating voltage input Vin and the ground GND, operating voltage Vin is carried out filtering, prevent that also the conduction interference that the push-pull oscillator of this circuit produces from influencing other power consumption equipment through power circuit; Filtered input voltage inserts biasing circuit, and biasing circuit is composed in parallel by resistance R 1 and capacitor C 1, resistance R 1 and capacitor C 1 back in parallel one termination input voltage vin; Resistance R 1 is with capacitor C 1 and meet the former limit feedback winding N that the back other end is connected to transformer B1 _B1And N _B2Centre cap on, recommend triode TR1, TR2 base stage for two and connect the former limit of transformer B1 feedback winding N respectively _B1And N _B2The other end on; Two emitters of recommending triode TR1, TR2 are ground connection all, and two collector electrodes connect the former limit of transformer B1 winding N respectively _P1And N _P2Two terminations, also connect second capacitor C 2 between two collector electrodes, former limit winding N _P1And N _P2Centre cap connect operating voltage Vin; The secondary winding N of transformer B1 _S1And N _S2Comprise that centre cap connects output filter circuit to the converter voltage output; The magnetic core of transformer B1 adopts the Rong Ling magnetic core; Output filter circuit is the full-wave rectifying circuit of rectifier diode D1 and D2 and output filter capacitor C3 composition.

Embodiment one adopts increases capacitor C 2; and the magnetic core of transformer B1 adopts the Rong Ling magnetic core; again capacitor C 1 is adopted the adjustment method of preamble technical scheme; realize the excellent protection function; simultaneously because the existence of Rong Ling magnetic core; have the conversion efficiency height, because the existence of capacitor C 2, embodiment one starts very fast when powering on.

Also just because of the existence of first capacitor C 1; first capacitor C 1 and resistance R 1 parallel connection; when powering on; because capacitance terminal voltage can not suddenly change; be equivalent to instantaneous short circuit, at this moment directly to base stage, the emitter discharge of triode TR1 with TR2, impulse current damages to recommend easily uses triode to operating supply voltage Vin by lead internal resistance, stray inductance, the internal resistance of feedback winding; shown in the embodiment two is exactly the modified model embodiment, has protected to recommend with triode not to be damaged.

Embodiment two

Embodiment two adopts the circuit theory diagrams of Fig. 5, the place different with Fig. 4 embodiment one, and biasing circuit is composed in series by resistance R 1 and capacitor C 1, and after resistance R 1 and 1 series connection of first capacitor C, tie point connects transformer feedback winding N _B1And N _B2Centre cap on, the terminal that resistance R 1 is not connected with first capacitor C 1 is connected the feeder ear Vin of operating voltage, the terminal that first capacitor C 1 is not connected with resistance R 1 is connected the ground connection of operating voltage.The parameter of other annexation, circuit is all with embodiment one.

When powering on, operating supply voltage will be through 1 charging of 1 pair of capacitor C of resistance R, when the terminal voltage of capacitor C 1 will surpass base stage, the emitter conducting voltage of triode TR1 among Fig. 5 or TR2, circuit just begins starting of oscillation, because there is not the impulse current to triode TR1 or TR2 emitter junction in the existence of capacitor C 1 when powering on.Protected the base stage of triode TR1 or TR2 to the PN junction of emitter, visible embodiment two has realized previously described other beneficial effect equally.

Embodiment three

Embodiment three adopts the circuit theory diagrams of Fig. 6, the place different with Fig. 5, and in the biasing circuit, resistance R 1 is originally substituted by constant-current source 100.After described constant-current source 100 and 1 series connection of first capacitor C, tie point connects transformer feedback winding N _B1And N _B2Centre cap on, the terminal that constant-current source 100 is not connected with first capacitor C 1 is connected the feeder ear Vin of operating voltage, the terminal that first capacitor C 1 is not connected with constant-current source 100 is connected the ground connection of operating voltage.Other annexation is all with embodiment one.

Wherein, the circuit bank of constant-current source 100 becomes known technology, constant-current source 100 is made up of resistance R 4 and resistance R 3 and positive-negative-positive triode TR4 and TR3, its annexation is known technology, can be referring to " Basic Analog Electronics " second edition by the Tong Shibai chief editor, the ISBN of this book number is 7-04-000868-8/TN53,266 pages of figure P3-21,270 pages of figure P3-32 in " Basic Analog Electronics ", so here no longer describe in detail, its continuous current is about:

$\mathrm{Io}=\frac{U_{\mathrm{BE}}}{R_3}$ Formula (1)

Io is the continuous current of the collector electrode of triode TR3 among Fig. 6 in the formula, U _BEBe base stage, the emitter voltage drop of triode TR4, silicone tube is generally got about 0.6V at normal temperatures, U _BEPressure drop at room temperature has negative temperature coefficient to be about-1.9 to-2.5mV/K, gets usually-2mV/K.Work as U _BEU _T, U _TVoltage equivalent for temperature also has the formula detailed calculated:

$U_{\mathrm{BE}}=U_T\ln \frac{\mathrm{Ie}}{I_s}$ Formula (2)

Wherein Ie is the emitter current of triode, Is is the reverse saturation current of the emitter junction of triode, reverse saturation current Is is relevant with the concentration of few son, and few son is relevant with temperature, temperature is low, reverse saturation current Is is just low, and its formula can be with reference to the formula (1-1) of the 3rd page in above-mentioned " Basic Analog Electronics " text; The characteristic of coming out on last surface is exactly that temperature is more low, U _BEPressure drop is just more big, and like this, the constant current value that above-mentioned formula (1) calculates is just more big.The definition of few son is referring to above-mentioned " Basic Analog Electronics " the 5th page of the 1st row and 13 row.

Namely, along with temperature reduces, the continuous current of the constant-current source 100 in Fig. 6 circuit all can become greatly, and so at low temperatures, constant-current source can provide bigger electric current to two triode TR1 that recommend usefulness and TR2 base stage, at low temperatures, the multiplication factor of two triodes reduces, but because its base stage obtains bigger electric current, its collector electrode can obtain bigger electric current, easily approach or reach the saturation point of magnetic core, two triodes enter very soon and utilize in the push-pull oscillator that the magnetic core saturation characteristic carries out.And at normal temperatures, the electric current that constant-current source provides is less, but still can satisfy the peak power output requirement of self-excitation push-pull converter, at this moment, when these two triode TR1, TR2 take turns saturation conduction, because collector current reduces because of base electrode, the saturation depth of transformer B1 magnetic core will leave district more deeply, cause that loss reduces, self-excitation push-pull converter efficient at normal temperatures will further be gone up.

Adopting TR4 in two diodes series connection alternate figures 6 also is the function that can realize constant-current source 100.

Only be preferred implementation of the present utility model below, should be pointed out that above-mentioned preferred implementation should not be considered as restriction of the present utility model, protection range of the present utility model should be as the criterion with claim institute restricted portion.For those skilled in the art, in not breaking away from spirit and scope of the present utility model, can also make some improvements and modifications, these improvements and modifications also should be considered as protection range of the present utility model.As the output winding simultaneously also around thin portion or the part of Rong Ling magnetic core, to obtain the small reduction of output ripple; As thin portion or the part of the driving winding of self-driving type synchronous rectification around the Rong Ling magnetic core, can promote the conversion efficiency of self-excitation push-pull converter equally.

Claims (3)

1. self-excitation push-pull converter, comprise biasing circuit, recommend two triodes, transformer and output filter circuits of usefulness, it is characterized in that: the magnetic core of described transformer is the Rong Ling magnetic core, connects second electric capacity between described two transistor collectors of recommending usefulness.

2. self-excitation push-pull converter according to claim 1 is characterized in that described biasing circuit is made up of first resistance and first electric capacity.

3. self-excitation push-pull converter according to claim 1 is characterized in that described biasing circuit is made up of constant-current source and first electric capacity.

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