CN102497101B - Self-excited Buck circuit - Google Patents
Self-excited Buck circuit Download PDFInfo
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- CN102497101B CN102497101B CN201110459166.6A CN201110459166A CN102497101B CN 102497101 B CN102497101 B CN 102497101B CN 201110459166 A CN201110459166 A CN 201110459166A CN 102497101 B CN102497101 B CN 102497101B
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Abstract
The invention discloses a self-excited Buck circuit, which comprises an inductor L1, a capacitor C1, a diode D1, a switching tube V1 and output sampling resistors R11 and R12, wherein the inductor L1, the capacitor C1, the diode D1 and the switching tube V1 form a Buck main circuit; and the output sampling resistors R11 and R12 are connected in series with each other, and then are connected in parallel with a load end. The self-excited Buck circuit further comprises a current sampling resistor R1, a PNP type triode Q1, a proportion-integration (PI) regulation circuit and a self-excited driving circuit. By the self-excited Buck circuit, the problem of low output voltage stability of the conventional self-excited Buck circuit is solved.
Description
Technical field
The present invention relates to a kind of self-excited Buck circuit.
Background technology
In middle low power application scenario, to compare with linear voltage-stabilizing circuit with separated exciting DC/DC converter, it is simple that auto-excitation type DC/DC converter has circuit, and components and parts are few, and efficiency is high, low cost and other advantages.
The main switch of auto-excitation type Buck converter generally adopts bipolar transistor to realize at present; Realize the control of opening to switching tube by output inductor being increased to auxiliary winding; By the signal to after output voltage sampling and the voltage Vbe comparison of triode, realize the shutoff control to switching tube by certain circuit, and then reach the object of output voltage stabilization.
China ZL99108088.2 patent discloses a kind of auto-excitation type Buck converter circuit, as shown in Figure 1.Vi, Vo are respectively direct current input, the output voltage of converter, are made up of the main circuit of Buck converter PNP transistor Q1, coupling inductance L1, diode D1 and capacitor C 2.Output voltage is received the base stage of NPN transistor Q3 after by resistance R 5, R6 dividing potential drop, and the collector electrode of Q3 is just connected with input voltage by resistance R 1, R2, and the emitter of Q3 is directly connected with the ground of main circuit.The emitter of PNP transistor Q2 is connected with base stage respectively at the emitter of transistor Q1 with collector electrode, and the base stage of Q2 is connected with the tie point of resistance R 1 and R2.Coupling inductance L2 connects with capacitor C 1 and resistance R 3 afterwards and emitter and the base stage of transistor Q1.The base stage of transistor Q1 is connected with the ground of main circuit by resistance R 4.The operation principle of this circuit is as follows: in the time that input voltage just powers on, and Q1 saturation conduction, D1 cut-off, reaches maximum voltage on coupling inductance L2, and L1, C2 start charging energy-storing.In charging process, L1 electric current increases, output voltage increases, the emitter voltage of Q1 also increases thereupon, the working point of Q1 is exited saturation region gradually, L1 both end voltage starts to decline thereupon, the upper both end voltage of coupling inductance L2 declines gradually, strengthen the shunt volume to Q1 base current simultaneously, caused positive electric current and the collector current of Q1 to reduce, further increased the emitter voltage of Q1, circuit enters positive feedback, and then cause the collector current of Q1 to reduce rapidly, in the time being less than L1 electric current, D1 conducting is L1 afterflow, Q1 cut-off.After this energy is released in L1 electric discharge, and L1 electric current reduces gradually, and finishing its electric current until L1 electric discharge is 1 o'clock, D1 cut-off, and Q1 is saturation conduction again, enters next from flyback cycle.Each can make output voltage improve from flyback cycle, some all after dates, and in the time that output voltage reaches the output voltage of setting, Voltage Feedback branch road R5, R6, Q3, R1, R2 and Q2 start working.When output voltage is during higher than set point, output voltage makes Q3 conducting after by R5, R6 dividing potential drop, and resistance R 1, the upper voltage of R2 increase, and then Q2 conducting shunt the base current of a part of Q1, reaches to shorten Q1 ON time, extend the Q1 pipeline section time.When output voltage is during lower than set point, Q3 cut-off, Q2 cut-off, recovers again former state the switching time of Q1.Principle thus, circuit is realized the stable of output voltage.The weak point of this circuit is:
(1) due to main switch Q1 use PNP transistor, while normally work the turn-on and turn-off time longer, when the degree of depth is saturated, conduction voltage drop is large, causes the efficiency of converter not high.
(2) output voltage by after electric resistance partial pressure with the comparison of transistorized Vbe conducting voltage, and then realize the stable of output voltage, and transistorized conduction voltage drop alters a great deal in the time of variation of ambient temperature, cause the output voltage of this circuit to change along with the variation of ambient temperature.
Summary of the invention
Technology of the present invention is dealt with problems and is: a kind of self-excited Buck circuit.Employing the invention solves the inadequate problem of output voltage stabilization degree in existing self-excitation type Buck circuit.
Technical solution of the present invention is:
A kind of self-excited Buck circuit, comprise: inductance L 1, capacitor C 1, diode D1, switching tube V1 and output sampling resistor R11, R12, wherein, inductance L 1, capacitor C 1, diode D1, switching tube V1 form Buck main circuit, after connecting mutually, output sampling resistor R11 and R12 be parallel to load end, also comprise: current sampling resistor R1, PNP triode Q1, PI regulating circuit, self-excitation drive circuit;
One end of described current sampling resistor R1 is connected with input voltage with the emitter of PNP triode Q1; The other end of described current sampling resistor R1 is connected with switching tube V1 drain electrode; Be connected in again the base stage of PNP triode Q1 simultaneously with the output of described PI regulating circuit; The input of described PI regulating circuit is connected with R12 with output sampling resistor R11; The output current of described PNP triode Q1 is for the shutoff of control switch pipe V1;
Described self-excitation drive circuit is connected in grid and the source electrode of switching tube V1.
Described PI regulating circuit comprises benchmark pressurizer.
Described self-excitation drive circuit is composed in series mutually by coupling inductance, electric capacity and resistance; Described coupling inductance and inductance L 1 adopt same magnetic core.
Be parallel with a diode at the two ends of described self-excitation drive circuit.
The present invention compared with prior art beneficial effect is:
(1) in PI regulating circuit of the present invention, adopt benchmark pressurizer to realize feedback and the closed-loop control to output voltage, more stable than the control of existing self-excitation Buck converter technique, output voltage regulation is better, even if also can ensure the constant voltage output of converter in the very large occasion of range of temperature.
(2) in self-excitation drive circuit of the present invention, realize circuit by coupling inductance in switching tube open control, in this partial circuit, increase a diode, make coupling inductance close and have no progeny and can charge for driving capacitor C 3 at switching tube, and then having reduced the coupling inductance number of turn, self-excited circuit is more easily realized.
(3) the present invention utilizes current sampling resistor R1 Buck main circuit current is sampled and combine and control with PI regulating circuit; in the time of main circuit generation overcurrent or short trouble; can, by reducing output voltage, realize the protection to Buck circuit and load.
Brief description of the drawings
Fig. 1 is auto-excitation type Buck converter circuit figure;
Fig. 2 is schematic diagram of the present invention;
Fig. 3 is fundamental diagram.
Embodiment
Just by reference to the accompanying drawings the specific embodiment of the invention is described further below.
As shown in Figure 2, the present invention is described auto-excitation type Buck translation circuit, comprise: inductance L 1, capacitor C 1, diode D1, switching tube V1 and output sampling resistor R11, R12, also comprise current sampling resistor R1, PNP triode Q1, PI regulating circuit, self-excitation drive circuit.PI regulating circuit comprises benchmark pressurizer D3, capacitor C 2 and resistance R 6, R8.Self-excitation drive circuit comprises coupling inductance L2, capacitor C 3, resistance R 10.
In circuit, Vi, Vo are respectively input, the output voltage of converter.Inductance L 1, capacitor C 1, diode D1, switching tube V1 form Buck main circuit.In Buck main circuit, current sampling resistor R1 is series in Buck main circuit.Wherein, one end of current sampling resistor R1 is connected with input voltage anode with the emitter of PNP triode Q1, and the other end of current sampling resistor R1, by being connected with switching tube V1 drain electrode, utilizes current sampling resistor R1 to realize the sampling to inverter main circuit electric current.
In PI regulating circuit, resistance R 8 and capacitor C 2 are connected in series in reference edge and the cathode terminal of benchmark pressurizer D3, for realizing the FEEDBACK CONTROL of converter, realize stablizing output voltage.The reference edge of D3 is connected with the divider resistance R12 of output with capacitor C 2.The cathode terminal of benchmark pressurizer D3 is connected with emitter with the base stage of PNP triode Q1 with R6 by resistance R 3 respectively, and the anode of benchmark pressurizer D3 is directly connected in Bcuk main circuit, thereby ensures the power supply to benchmark pressurizer D3.This part circuit can be realized the shutoff moment of switching tube V1 and control.
The two ends of self-excitation drive circuit are connected with source electrode with the grid of switching tube V1 respectively, and the anode of diode D2 is connected respectively at the collector and emitter of triode Q3 with negative electrode.Coupling inductance L1 mark is of the same name to be distolaterally connected with the negative electrode of diode D1, and coupling inductance L2 and inductance L 1 adopt same magnetic core.Unmarked of the same name be distolaterally connected with the source electrode of V1 of coupling inductance L2, the L2 mark distolateral negative electrode that is connected to D2 after connecting with resistance R 10 and capacitor C 3 of the same name, realizes the moment of opening of switching tube and controls.
The collector electrode of above-mentioned PNP triode Q1 is connected with the base stage of NPN triode Q2 by resistance R 4, and the base of Q1 is connected in the utmost point in the drain electrode of metal-oxide-semiconductor V1 by resistance R 2.The resistance R 4 being connected with the collector electrode of Q1 is connected in the negative terminal of input by resistance R 5.The emitter of triode Q2 is connected in Bcuk main circuit, and collector electrode is connected with the base stage of NPN triode Q3.The collector and emitter of triode Q3 is connected with the two ends of self-excitation drive circuit respectively.Between the base stage of Q3 and emitter, be also connected with resistance R 9.Be connected with resistance R 7 at the grid of switching tube V1 and the anode of input.
The operation principle of this auto-excitation type Buck converter is described below in conjunction with Fig. 3:
The t0 moment, input voltage Vi accesses power supply, input voltage provides driving voltage by resistance R 7 for switching tube V1, capacitor C 3 is charged, reach V1 conducting after V1 door capable of being opened voltage limit, being added in the upper voltage of coupling inductance L1 is Vi, and after coupling, inductance L 2 mark distolateral voltage of the same name is for just, in this voltage and capacitor C 3, voltage stack, maintains V1 conducting.After this inductance L 1 enters the energy storage stage, its Current rise, capacitor C 1 enters the charging stage, output voltage V o rises, after sampling feedback, benchmark pressurizer D3 cathode voltage VK is declined by maximum, and sampling resistor R1 both end voltage VR1 rises, and Vi and the Vk signal after resistance R 1, R2, R3 dividing potential drop superposes with VR1 again, the voltage of getting on resistance R 1 and R2 increases gradually, and Q1 emitter and base voltage across poles Veb increase gradually.
In the t1 moment, Veb is greater than the cut-in voltage Vebth of triode Q1, and Q1 enters amplification operating state, and R4 drives rapidly triode Q2 and then turn-on transistor Q3, V1 gate-source voltage is dragged down, and V1 cut-off, diode D1 conducting simultaneously, is inductance L 1 afterflow.After this, the upper voltage reversal of L1, the upper voltage reversal of coupling inductance L2, diode D2 conducting, is inductance L 2 afterflows, capacitor C 3 is charged simultaneously.Due to V1 cut-off, in resistance R 1, electric current is zero, and triode Q1, Q2, Q3 all end.After this in inductance L 1, electric current reduces gradually, and output voltage increases.
In the t2 moment, in inductance L 1, electric current reduces at 1 o'clock, diode D1 cut-off, and inductance L 1, the upper voltage of L2 are zero, and the voltage triggered V1 conducting in capacitor C 3, enters next from flyback cycle.Later each in flyback cycle V1 be all open-minded by the voltage triggered in capacitor C 3, the shutoff of V1 causes by triggering Q1 conducting.
Each can make output voltage improve from flyback cycle, some all after dates, and output voltage is increased to set point.In the time that output voltage exceedes set point, benchmark pressurizer cathode current increases, Vk declines, the voltage of getting on R1, R2 increases, and now resistance R 1 is constant from the voltage triangular wave slope of main circuit up-sampling, the voltage after stack increases, and the Q1 conducting moment in advance, and then converter duty ratio reduces, output voltage is reduced; In the time that output voltage reduces, the upper electric current of D3 reduces, Vk increases, the voltage of getting on R1, R2 reduces, and resistance R 1 is still constant from the triangular wave slope of main circuit up-sampling, and the voltage after stack reduces, the Q1 saturation conduction moment lags behind, and then the increase of converter duty ratio, output voltage is increased, final converter reaches the state of output voltage stabilization.
This circuit has current protecting function, by changing the value of resistance R 1, can realize the setting to over-current protection point.In the time that main circuit current increases, in resistance R 1, pressure drop increases, and in the time that the upper voltage of R1 is enough to open Q1, enters current protection state; Load current continues to increase afterwards, and output voltage decreases, until output voltage is constant, now circuit working is at output short circuit protection state.
The unexposed technology of the present invention belongs to general knowledge as well known to those skilled in the art.
Claims (1)
1. a self-excited Buck circuit, comprise: inductance L 1, capacitor C 1, diode D1, switching tube V1 and output sampling resistor R11, R12, wherein, inductance L 1, capacitor C 1, diode D1, switching tube V1 form Buck main circuit, after connecting mutually, output sampling resistor R11 and R12 be parallel to load end, characterized by further comprising: current sampling resistor R1, PNP triode Q1, PI regulating circuit, self-excitation drive circuit; Described switching tube V1 is N-channel MOS pipe;
One end of described current sampling resistor R1 is connected with input voltage with the emitter of PNP triode Q1; The other end of described current sampling resistor R1 is connected with switching tube V1 drain electrode; Be connected in again the base stage of PNP triode Q1 simultaneously with the output of described PI regulating circuit; The input of described PI regulating circuit is connected with R12 with output sampling resistor R11; The output current of described PNP triode Q1 is for the shutoff of control switch pipe V1;
Described self-excitation drive circuit is connected in grid and the source electrode of switching tube V1;
Described PI regulating circuit comprises benchmark pressurizer, resistance R 8, capacitor C 2, and resistance R 8 and capacitor C 2 are connected in series in reference edge and the cathode terminal of benchmark pressurizer D3;
Described self-excitation drive circuit is composed in series mutually by coupling inductance, electric capacity and resistance; Described coupling inductance and inductance L 1 adopt same magnetic core;
Be parallel with a diode at the two ends of described self-excitation drive circuit.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201110459166.6A CN102497101B (en) | 2011-12-29 | 2011-12-29 | Self-excited Buck circuit |
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| CN201110459166.6A CN102497101B (en) | 2011-12-29 | 2011-12-29 | Self-excited Buck circuit |
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| CN102497101A CN102497101A (en) | 2012-06-13 |
| CN102497101B true CN102497101B (en) | 2014-11-19 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103441672B (en) * | 2013-07-25 | 2016-02-10 | 北京控制工程研究所 | A kind of self-excitation BUCK circuit based on auxiliary winding type sample circuit |
| CN104716832B (en) * | 2013-12-16 | 2019-03-29 | 深圳市海洋王照明工程有限公司 | A kind of switching power supply |
| CN103997212B (en) * | 2014-06-10 | 2016-04-20 | 杭州钛丽能源科技有限公司 | The self-excitation Sepic converter of input adaptive |
| CN103986329B (en) * | 2014-06-10 | 2016-06-08 | 杭州钛丽能源科技有限公司 | The self-excited type Cuk umformer of input self-adaptation |
| CN109586564A (en) * | 2018-12-19 | 2019-04-05 | 华北电力大学 | A kind of high stability cuk converter |
| CN110634448B (en) * | 2019-08-23 | 2021-03-23 | 深圳康佳电子科技有限公司 | Backlight lamp strip protection circuit and TV set |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101877532A (en) * | 2010-06-28 | 2010-11-03 | 浙江工业大学 | Bipolar transistor auto-excitation type Buck convertor |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS63154066A (en) * | 1986-12-16 | 1988-06-27 | Sanken Electric Co Ltd | Chopper type dc power source |
| JP3131428B1 (en) * | 1999-12-16 | 2001-01-31 | ニチコン株式会社 | Chopper circuit |
| JP2002199706A (en) * | 2000-12-27 | 2002-07-12 | Seiko Epson Corp | Dc-dc conversion circuit |
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| CN101877532A (en) * | 2010-06-28 | 2010-11-03 | 浙江工业大学 | Bipolar transistor auto-excitation type Buck convertor |
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| JP昭63-154066A 1988.06.27 * |
| JP特开2001-178119A 2001.06.29 * |
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