CN103248238A - Ringing choke converter - Google Patents
Ringing choke converter Download PDFInfo
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- CN103248238A CN103248238A CN201210026265XA CN201210026265A CN103248238A CN 103248238 A CN103248238 A CN 103248238A CN 201210026265X A CN201210026265X A CN 201210026265XA CN 201210026265 A CN201210026265 A CN 201210026265A CN 103248238 A CN103248238 A CN 103248238A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/338—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in a self-oscillating arrangement
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Abstract
The invention provides a ringing choke converter which can achieve a soft start function, provides appropriate driving compensation for start and stable-state stages of a product, improves the anti-interference capacity and the stability of the product, and expands a design scope of input voltage of the ringing choke converter and a variation scope of a load. A direct-current input signal inputted by a power input end of the ringing choke converter outputs a direct-current signal after passing an input filter circuit, a main power circuit and an output filter circuit sequentially; the main power circuit comprises a main power tube and a main transformer; the outputted direct-current signal conducts negative feedback control on the main power tube through a voltage stabilizing circuit, an isolating optical coupler and a driving control circuit to achieve stable output; the ringing choke converter further comprises a soft start circuit with a constant current source; and the soft start circuit is connected between an output end of the input filter circuit and the driving control circuit.
Description
Technical field
The present invention relates to a kind of self-oscillation anti exciting converter, particularly a kind of self-oscillation anti exciting converter with the constant-current source soft starting circuit.
Background technology
Self-oscillation flyback converter (Ringing Choke Converter) is because its design cost is lower, has the stronger market competitiveness and enjoys designer's favor; Yet the quality of its output characteristic depends on the consistency of each discrete component to a great extent, and when the consistency of components and parts such as transformer, main power tube, control triode, optocoupler is more good, its output performance is also more stable.Therefore reduce self-oscillation inverse-excitation converting circuit (RCC) to the conforming harsh requirement of discrete device, improve its output voltage stability and become the emphasis that the designer considers.The designer adopts bias compensation circuit (the control transistor base adds the shutoff compensation) more at present, the stability of its output voltage obtains raising to a certain degree, yet this scheme debugging difficulty is big, consistency of product is still relatively poor, especially increases, influences when output capacitive loading increases more obvious in power output.
The comparatively desirable circuit form of a kind of self-oscillation anti exciting converter (RCC) is disclosed among the Chinese invention patent ublic specification of application CN101997423A, as shown in Figure 1, this self-oscillation anti exciting converter mainly comprises filtering part, soft start part, metal-oxide-semiconductor, transformer, pulse frequency modulated part (PFM), accessory power supply, isolation optocoupler, voltage stabilizing output loop part.The input electric weight connects the output loop part through transformer, soft start partly connects the grid of metal-oxide-semiconductor, the grid of metal-oxide-semiconductor also connects the pulse frequency modulated part, accessory power supply connects the pulse frequency modulated part, the indirection reference amplifier section of pulse frequency modulated part and voltage stabilizing output loop part, isolation optocoupler form voltage negative feedback loop.
The soft starting circuit of above-mentioned anti exciting converter, improved the stability of output voltage when product starts, its operation principle is: after input powers on, soft starting circuit voltage raises, the metal-oxide-semiconductor conducting, output voltage rises gradually, before system enters stable state, soft starting circuit continues as metal-oxide-semiconductor the driving energy is provided, and soft starting circuit voltage reduces gradually simultaneously; After system's operate as normal since the soft starting circuit charging interval much larger than discharge time, soft starting circuit remains at than electronegative potential (during the starting up, the soft start voltage waveform is seen Fig. 7).The shortcoming of this soft starting circuit is: during stable state, capacitor C 9 velocities of discharge are far faster than charging rate in the soft starting circuit, its voltage to earth is seen Fig. 7 near 1V(), therefore metal-oxide-semiconductor drives the feedback winding energy that places one's entire reliance upon, to the metal-oxide-semiconductor undercompensation, the product output performance is subjected to influences such as transformer technology (feedback and input degree of coupling), metal-oxide-semiconductor turn-on threshold, the external capacitive load of output easily during the soft starting circuit operate as normal.When increasing charging rate, be subjected to wide input voltage range and output loading variation influence greatly, overcompensation appears easily, cause shortcomings such as power supply starting up current limliting and product output short-circuit power consumption are big.
Fig. 2 is the circuit theory diagrams of a disclosed embodiment among the Chinese invention patent ublic specification of application CN101997423A, comprises input filter circuit 11, soft starting circuit 12, pulse frequency modulation circuit 13, main power circuit 14, auxiliary power circuit 15, output filter circuit 16, isolates optocoupler OC1, error amplification ADJ circuit 17.Input filter circuit 11 is made up of filter capacitor C0, filter capacitor C1 and filter inductance L0, has formed π type filter circuit.Capacitor C 0 connects power input, other end ground connection, and inductance L 0 connects power input, another termination transformer end of the same name, the termination transformer end of the same name of capacitor C 1, other end ground connection.Also can adopt other existing filter circuit, specifically can be selected by the relevant technologies handbook.Soft starting circuit 12 comprises: divider resistance R10, resistance R 13, resistance R 14 and startup capacitor C 9.Resistance R 10, resistance R 13, resistance R 14 are connected successively, a termination power input of series circuit, an end ground connection.One termination of capacitor C 9 is gone into the node of connecting of resistance R 10 and resistance R 13, other end ground connection.Its operation principle is for when inserting input voltage, and electric current is through 9 chargings of 10 pairs of capacitor C of resistance R, elapsed time
Back capacitance voltage reaches the MOS threshold voltage, realizes the start soft start function; When metal-oxide-semiconductor turn-offs, the feedback winding is reverse, terminal potential of the same name is for negative, therefore the metal-oxide-semiconductor current potential is also for negative, this moment, capacitor C 9 was by resistance R 13 repid discharges, when the metal-oxide-semiconductor conducting, input voltage charges to capacitor C 9 by resistance R 10, because the resistance of resistance R 10 is far longer than the resistance of resistance R 13 (when the R10 value reduces, product output short-circuit power consumption increases, and starting current increases, and table two has exemplified the deficiency of bringing when the R10 value reduces), therefore the velocity of discharge finishes through back capacitor C 9 energy release after a while far faster than charging rate.Pulse frequency modulation circuit 13 comprises: resistance R 6, resistance R 9, resistance R 11, resistance R 111, capacitor C 5, capacitor C 6, capacitor C 12, NPN type triode TR2, positive-negative-positive triode TR3, positive feedback winding P3.Capacitor C 6 is connected successively with resistance R 11, resistance R 111, resistance R 6, and a termination of series circuit is gone into the end of the same name of positive feedback winding P3, and the other end inserts the collector electrode of triode TR2.Capacitor C 5 is in parallel with resistance R 9, and a termination of parallel circuits is gone into the base stage of triode TR2, and the other end inserts the collector electrode of triode TR3.Capacitor C 12 is in parallel with resistance R 111, and a termination of parallel circuits is gone into the emitter of triode TR3, and the other end inserts the collector electrode of triode TR3.Its operation principle is: positive feedback winding P3, capacitor C 6, resistance R 11 branch roads constitute the self-oscillation loop by being coupled with the former secondary of main power tube TR1, and the conducting of control switch pipe is turn-offed; Electric current loop R5 branch road, Voltage loop optocoupler branch road make product output normal by two-tube Drive and Control Circuit TR2, TR3 by-pass cock pipe conducting duty ratio simultaneously.Main power circuit 14 comprises: the former limit of transformer winding P1, output winding P2, and metal-oxide-semiconductor TR1, output rectifier diode D1 realizes that conversion, transmission and input and the output of power supply energy is isolated.Accessory power supply 15 comprises: positive feedback winding P3, diode D3, and its operation principle is, and feedback winding end of the same name is timing, and diode D3 conducting is for optocoupler provides energy.Output filter circuit 16 comprises filter capacitor C3, also can adopt other existing filter circuit, specifically can be selected by the relevant technologies handbook.Isolating optocoupler comprises: optocoupler OC1, it mainly finishes transmission and the input and output buffer action of signal.Error is amplified ADJ circuit 17 and comprised: sample circuit, signal be amplifying circuit relatively.Its operation principle is: output voltage floats when high, and sample circuit is gathered signal and relatively regulated the optocoupler primary current behind the amplifying circuit through signal, namely regulates the duty ratio of product by Voltage loop.There is flow through sample circuit, error of a sampling current to amplify, the main power tube in the main power circuit is carried out negative feedback control after isolating optocoupler, pulse frequency modulated PFM circuit at the output of power supply; Output at input filter circuit is connected with a soft starting circuit, and this soft starting circuit other end and pulse frequency modulated PFM are connected to realize the soft start function of power supply.
The shortcoming of foregoing circuit is:
1) product the startup stage, band is fully loaded, especially during large capacitive load, can not enter stable state, the product output abnormality; After the foregoing circuit start, need be through vibration after a while, product just can enter stable state; In unstable state period, feedback winding energy a little less than, rely on capacitor C 9 compensation energy this moment, (capacitor C 9 start voltage waveforms are seen Fig. 7 yet capacitor C 9 voltages begin after the metal-oxide-semiconductor conducting period 1 to descend, its voltage descends gradually after the metal-oxide-semiconductor conducting), provide energy more and more a little less than, so this circuit is in full load, underload, especially during large capacitive load, vibration easily, it is on the low side to show as output voltage.When output band capacitive load, the product output voltage rising rise time is elongated, it is that PWB4805D, power are the supply convertor operate as normal of 3W and the output voltage waveforms during with 1000 μ f electric capacity that Figure 12 has contrasted model, wherein CH1 is the operate as normal waveform, rise time is about 0.5ms, CH2 is the work wave with 1000 μ f electric capacity, rise time is about 3.7ms, Voltage loop was not in runaway condition when output voltage was formally set up, this moment, metal-oxide-semiconductor drove if can not obtain adequate remedy, the easy failure of oscillation of feedback winding shows as poor starting.Below introduce this phase process in detail: be that the supply convertor of 3W is example with existing PWB4805D, power, its start-up circuit parameter has been taken into account key performances such as short-circuit dissipation, starting current, circuit theory is seen Fig. 2, each parameter value is as follows in this soft starting circuit 12: R10=332 Κ Ω, R13=3.3 Κ Ω, R14=150 Κ Ω, C9=1 μ f, the feedback winding drives branch road R11=100 Ω in the control circuit 13, C6=4700PF, main power circuit 14 parts, each parameter of its transformer T1 is: Np=25, Ns=7, Nf=8.Product is in the starting stage of metal-oxide-semiconductor conducting, the feedback winding voltage is less, this stage G electrode potential is almost nil, so unstable state discharge time constant in period can be approximately T2 ≈ R13*C9 ≈ 3.3ms, charge constant T1 ≈ R14*C9=332ms again, so unstable state period, capacitor C 9 current potentials descend gradually after the metal-oxide-semiconductor conducting, and Fig. 7 has shown the voltage waveform on (test condition: underloading Io=0.06A, high pressure 72V test) capacitor C 9, after the metal-oxide-semiconductor conducting, capacitance voltage descends gradually.Above-mentioned parameter R10 value is 332 Κ Ω, has taken into account starting up's electric current and the output short-circuit power consumption of product.Table one has exemplified input voltage 18V, 48V, 72V, the power supply starting up irreducible minimum flow valuve when being fully loaded with Io=0.6A and the output short-circuit power consumption under the each point condition.
Table one
| Test event | Low pressure 18V | Nominal 48V | High pressure 72V |
| Output short-circuit power consumption (W) | 0.216 | 0.576 | 0.792 |
| Operate as normal is fully loaded with input current (mA) Iin | 209 | 83 | 63 |
| Start minimum limit electric current (mA) I Limit | 213 | 140 | 140 |
| Starting current multiple (I Limit/Iin） | 1.019 | 1.686 | 2.222 |
Table two has exemplified R10 when getting 332 Κ Ω, the average voltage of capacitor C 9 under different loads and input voltage condition.
Table two
As can be seen from Table I, product starting current, short-circuit dissipation are all less, and maximum short-circuit dissipation is 0.792W only; As can be seen from Table II, when the R10 value was big, Vc9 change in voltage scope was big, and to the compensation intensity instability that metal-oxide-semiconductor drives, it is the poorest to compensate during the underloading high pressure, and voltage is 1.02V only.When the R10 value diminishes, its charge constant T1=R10*C9 reduces, the energy compensating of capacitor C 9 strengthens, owing to reduce R10, its compensation intensity is not easy control, especially is difficult to take into account the compensation intensity of each point at input voltage, product that the load variations scope is big, and its shortcoming of bringing is: 1) starting up's electric current becomes big by 2) short-circuit dissipation increases, especially short-circuit dissipation increases obviously when high pressure, and product is burnt when serious.After table three has exemplified and has changed R10 into 50 Κ Ω by 332 Κ Ω, output short-circuit power consumption and the starting current of product.Table four has exemplified the average voltage of capacitor C 9 under this condition.
Table three
| Test event | Low pressure 18V | Nominal 48V | High pressure 72V |
| Output short-circuit power consumption (W) | 2.214 | 3.264 | 3.96 |
| Operate as normal is fully loaded with input current (mA) Iin | 209 | 83 | 63 |
| Start minimum limit electric current (mA) I Limit | 247 | 247 | 242 |
| Starting current multiple (I Limit/Iin） | 1.181 | 2.975 | 3.84 |
Table four
As can be seen from Table III: 1) all more former scheme increases of short-circuit dissipation, reach 3.96W during high pressure, long-time short circuit will damage product 2) starting current increases obviously, and especially the more former scheme of starting current increases nearly 1.7 times, startup current limliting when may cause the client to use this moment during high pressure.After table four is R10 value 50 Κ Ω, under different loads and the voltage conditions, the average voltage level of C9, after this table demonstration reduces R10, capacitor C 9 change in voltage under each loading condition is bigger, and maximum voltage is 12.8V, and minimum voltage is 4.39V only, it compensated strong, caused the product starting current big and short-circuit dissipation is big.On former scheme basis, change R13 into 7.5 Κ Ω by 3.3 Κ Ω after, the starting up is bad for nominal full load product, so discharge time constant allows to change less.To sum up, change the R10 value, it drives the compensation poor stability to metal-oxide-semiconductor, occurs overcompensation and undercompensation easily.
2) during stable state, under the high pressure underloading condition, capacitor C 9 velocities of discharge are faster than charging rate in the soft starting circuit, its voltage to earth is seen Fig. 7 near 1V(, underloading Io=0.06A, high pressure 72V test), so metal-oxide-semiconductor drives and almost completely depends on feedback winding energy, and this moment, the quality of product output performance depended on the coupling performance of two point: a, feedback winding and former limit winding; B, output loading.When feedback winding and input are coupled variation, under its couple drive energy variation, particularly input voltage saltus step condition, drive energy shortage, cause the product vibration easily; When output loading diminishes (below 10% load), feedback winding energy descends greatly, and its driving energy (couple current) also reduces, and product drives and enters the batch (-type) vibration, and it is on the low side to show as output voltage.When below introducing the high pressure underloading in detail, the course of work of product: be that the supply convertor of 3W is example with existing PWB4805D, power, its start-up circuit parameter has been taken into account key performances such as short-circuit dissipation, starting current, circuit theory is seen Fig. 2, each parameter value is as follows in this soft starting circuit 12: R10=332 Κ Ω, R13=3.3 Κ Ω, R14=150 Κ Ω, C9=1 μ f, the feedback winding drives branch road R11=100 Ω, C6=4700PF in the control circuit 13, main power circuit 14 parts, each parameter of its transformer T1 is: Np=25, Ns=7, Nf=8.Under the limit, (corresponding metal-oxide-semiconductor shutoff) end voltage to earth of the same name when the feedback winding is reverse
=-4.375V, because capacitor C 6 and metal-oxide-semiconductor GS junction capacitance Ciss(adopt its junction capacitance of IRFR220 metal-oxide-semiconductor Ciss to be about 300PF) the appearance value is little, and resistance R 11 values only are 100 Ω, when therefore metal-oxide-semiconductor turn-offs, the feedback winding is reverse, metal-oxide-semiconductor Ciss storage power discharges by PNP triode TR3 on the one hand, on the other hand by driving branch road R11, C6 discharges to feedback winding end of the same name, showing as metal-oxide-semiconductor Vgs current potential is dragged down rapidly, measured waveform is seen Fig. 8 (test condition: Vin=18V, Io=0.6A), from waveform as can be seen, metal-oxide-semiconductor off-phases Vgs ≈-0.64V.Therefore off-phases capacitor C 9 is discharged to the G utmost point by resistance R 13; The product switching frequency is more high, duty ratio is more little, be that the interior turn-off time of unit interval is long, therefore high frequency condition C9 is long discharge time, himself current potential is also lower, Fig. 7 has tested voltage waveform (the high pressure 72V on the C9 electric capacity, output loading 0.06A), after the metal-oxide-semiconductor conducting, capacitance voltage begins to descend as can be seen from this figure, and capacitance voltage has only 1V after the stable state, its corresponding drive waveforms is seen Fig. 9, T ≈ 1.07 μ s wherein, effectively ON time Ton ≈ 0.01 μ s(driving voltage is effective high level, i.e. Vgs greater than opening thresholding〉3.3V), D=0.0093, namely the time of metal-oxide-semiconductor 99.06% is in off state under this condition, therefore effectively discharge time constant T2 ≈ R13*C9=3.3ms, its charge constant T1=R10*C9=332ms again, thus T2＜＜T1.When reducing charge constant R10, increase R13 value, its shortcoming of bringing is with described unanimity under the unsteady state condition.
3) when extraneous factor interference control signal (for example static), switching tube is thoroughly closed within a short period of time, after disturbing disappearance, product needed can enter steady operation through soft start charging, metal-oxide-semiconductor conducting to two periods of output normal (being generally output rise time 0.5ms), this moment, output showed as the power down phenomenon.Figure 11 has tested the PWB4805D-3W product under high pressure, light-load conditions, after the input 4KV electrostatic interference, and output power down waveform, when this waveform showed input static, product was exported easy power down, disturbed client to restart when serious.Below introduce the power down reason in detail: circuit theory is seen Fig. 2, starts 12 parts, and R10=332 Κ Ω, C9 get 1 μ f, R13=3.3 Κ Ω; Switching tube adopts IRFR220, and looking into its thresholding of specifications is 2V-4V, surveys its turn-on threshold V (th)=3.3V, so the fastest start-up time during Vin=36V
=31.91ms, because the metering function of R13, can be longer than above-mentioned calculated value actual start-up time slightly, actual measurement is about 35ms, and therefore after electrostatic interference was turn-offed metal-oxide-semiconductor, product was if restart through soft starting circuit, then the turn-off time must be elongated, and product output shows as the power down phenomenon.This scheme reduces the R10 value, can strengthen the soft start compensation ability, reduce the power down risk, yet be subjected to input voltage and the big influence of load variations scope, reduce R10 and be difficult to compensation under compatible different input voltage point and the loading condition, bring when compensation intensity is excessive that short-circuit dissipation increases, starting current increases, compensate and to address the above problem again when too small.
Summary of the invention
The purpose of this invention is to provide a kind of self-oscillation anti exciting converter, can be when realizing soft start function, for the startup of product and steady-state process provide suitable driving compensation, improve product antijamming capability and stability, enlarge the scope of design of self-oscillation anti exciting converter input voltage and the excursion of load simultaneously.
The objective of the invention is to realize by following technical measures:
A kind of self-oscillation anti exciting converter, direct-flow input signal are exported direct current signal through behind input filter circuit, main power circuit and the output filter circuit successively, and main power circuit comprises main power tube and main transformer; The direct current signal of described output carries out negative feedback by voltage stabilizing circuit, isolation optocoupler and Drive and Control Circuit to main power tube successively and controls to realize stable output, also comprise the soft starting circuit of being with constant-current source, this soft starting circuit is connected between the output and described Drive and Control Circuit of described input filter circuit; When being in unstable state after described self-oscillation anti exciting converter powers on, by the soft starting circuit charging of constant-current source to the band constant-current source, soft start voltage rises to metal-oxide-semiconductor conducting after the metal-oxide-semiconductor threshold value, because constant current source charging speed and soft start capacitor velocity of discharge balance, soft start capacitor constantly provides to metal-oxide-semiconductor and drives compensation, realizes starting normal; Described self-oscillation anti exciting converter enters after the stable state, and constant current source charging speed and the soft start capacitor velocity of discharge are kept balance, and soft start continues to provide the driving compensation to metal-oxide-semiconductor, realizes the stable state operate as normal.
As one embodiment of the present invention, the soft starting circuit of described band constant-current source comprises constant-current source, first divider resistance, second divider resistance and starts electric capacity; The anode of described constant-current source is connected to the power input of self-oscillation anti exciting converter, the negative electrode of described constant-current source is connected to the power supply reference edge of self-oscillation anti exciting converter successively by described first divider resistance and second divider resistance, the series arm of described startup electric capacity and described first divider resistance and second divider resistance is in parallel, and the tie point of described first divider resistance and second divider resistance is connected with the grid of described main power tube.
More excellent, the soft starting circuit of described band constant-current source also comprises current-limiting resistance, the anode of described constant-current source is connected to the power input of self-oscillation anti exciting converter by described current-limiting resistance.
More excellent, the soft starting circuit of described band constant-current source also comprises current-limiting resistance, described current-limiting resistance is connected negative electrode and described first divider resistance of described constant-current source and starts between the tie point of electric capacity.
As one embodiment of the present invention, described constant-current source (D1A) is single constant-current source, or the constant-current source parallel form, or the constant-current source that is composited of constant-current source and triode, voltage-stabiliser tube, resistance, or the constant-current source that constitutes of triode and resistance.
Compared with prior art, the present invention has the following advantages:
One of advantage of the present invention: improve the converter product and start ability and band capacitance load capability, product can normally be started and steady operation when full load and band capacitive load.It is that WRF4815P, power are the former scheme and the band capacitance load capability contrast of adopting after the technical solution of the present invention of the supply convertor of 6W that table five has been enumerated model.
Table five
From table five as can be seen, adopt technical scheme of the present invention after, converter product tape capacitance load capability improves greatly.
Two of advantage of the present invention: output voltage stability when improving product underload (10% load is following), reduce the not enough hidden danger of driving that feedback winding energy when underload (electric current is less during underload, and coupling energy is weak) on the low side brings; Make the bigger nominal load current of self-oscillation flyback converter design become possibility simultaneously.
Three of advantage of the present invention: reduce product to the technological requirement (feedback requires to reduce with the input coupling coefficient) of transformer, reduce the conforming requirement of switching tube thresholding, improved the productibility of product.Figure 10 has enumerated the threshold test between the metal-oxide-semiconductor different batches that model is IRFR220.Test condition: Vgs=Vds and Id=250 μ A, T=25 ℃, as can be seen from the figure, metal-oxide-semiconductor thresholding cut-in voltage differs greatly between batch, YG batch of metal-oxide-semiconductor thresholding is higher than OM batch of metal-oxide-semiconductor thresholding, therefore its demand to feedback winding energy also increases, and the technology of the present invention is for metal-oxide-semiconductor provides suitable compensation, therefore the reliable driven MOS pipe of energy has reduced the coherence request to the metal-oxide-semiconductor turn-on threshold.
Four of advantage of the present invention: improve the product antijamming capability, efficiently solve output power down phenomenon.Adopting model in the experiment is that PWB4805D, power are that the supply convertor product of 3W is the single-chip microcomputer power supply, and when input was beaten 4KV static, single-chip microcomputer resetted, this supply convertor output power down; After adopting technical scheme of the present invention to improve, input is beaten 4KV static, and the output of converter product is normal, and single-chip microcomputer is working properly.
Five of advantage of the present invention: improved self-oscillation flyback converter adaptability in wide input voltage range (4:1).Because the startup of constant-current source, product toggle speed, compensation intensity when low pressure, nominal, high pressure are effectively controlled, make metal-oxide-semiconductor drive under full input voltage and full-load range and large capacitive load condition and reasonably compensated, efficiently solve problems such as short-circuit dissipation, starting current.After table six had been enumerated and adopted the constant-current source of 0.5mA, PWB4805D, power were short-circuit dissipation, the startability of the supply convertor of 3W.
Table six
| Test event | Low pressure 18V | Nominal 48V | High pressure 72V |
| Output short-circuit power consumption (W) | 0.594 | 0.624 | 0.72 |
| Operate as normal is fully loaded with input current (mA) Iin | 209 | 83 | 63 |
| Start minimum limit electric current (mA) I Limit | 213 | 180 | 180 |
| Starting current multiple (I Limit/Iin） | 1.019 | 2.16 | 2.85 |
Contrast table three, its short-circuit dissipation descends greatly as can be seen, and product possesses long-time short-circuit protection function; The starting current of each input voltage point all reduces than table three, reduces 67mA during nominal, reduces amplitude 37%, reduces client starting up power supply current limliting risk.
Description of drawings
The present invention is described in further detail below in conjunction with the drawings and specific embodiments:
Fig. 1 is the theory diagram of self-oscillation anti exciting converter in the prior art;
Fig. 2 is the circuit theory diagrams of self-oscillation anti exciting converter in the prior art;
Fig. 3 is the theory diagram of self-oscillation anti exciting converter of the present invention;
Fig. 4 is the circuit theory diagrams of the embodiment of the invention one;
Fig. 5 is the circuit theory diagrams of two kinds of bands of embodiment of the invention constant-current source soft starting circuit part;
Fig. 6 is the circuit theory diagrams of three kinds of bands of embodiment of the invention constant-current source soft starting circuit part;
Fig. 7 is for starting the voltage oscillogram of capacitor C 9 in the soft starting circuit of self-oscillation anti exciting converter;
Fig. 8 is that PWB4805D, power are the supply convertor low pressure of 3W, the Vgs drive waveforms figure of full load for model;
Fig. 9 is PWB4805D, the power Vgs drive waveforms figure when being supply convertor underloading, the high pressure of 3W for model;
Figure 10 is the normal temperature threshold test curve chart of the metal-oxide-semiconductor of IRFR220 for model;
Figure 11 is that model PWB4805D, power are the supply convertor input of 3W when beating 4KV static, output voltage waveform;
Figure 12 is that model PWB4805D, power are the supply convertor of 3W output voltage rising waveform figure when not being with capacitive load and being with 1000 μ f capacitive loads;
Figure 13 is the circuit theory diagrams of constant-current source parallel form;
Figure 14 is the circuit theory diagrams of the compound constant-current source of constant-current source, resistance, voltage-stabiliser tube, triode formation;
Figure 15 is the circuit theory diagrams of the constant-current source of PNP triode, resistance formation;
Figure 16 is the circuit theory diagrams of single tube Drive and Control Circuit.
Embodiment
The present invention is described in further detail below in conjunction with the drawings and specific embodiments.
As shown in Figure 3, self-oscillation anti exciting converter of the present invention, direct-flow input signal are exported direct current signal through behind input filter circuit, main power circuit and the output filter circuit successively, and main power circuit comprises main power tube and main transformer; The direct current signal of described output carries out negative feedback by voltage stabilizing circuit, isolation optocoupler and Drive and Control Circuit to main power tube successively and controls to realize stable output, also comprise the soft starting circuit of being with constant-current source, this soft starting circuit is connected between the output and described Drive and Control Circuit of described input filter circuit; When being in unstable state after described self-oscillation anti exciting converter powers on, by the soft starting circuit charging of constant-current source to the band constant-current source, soft start voltage rises to metal-oxide-semiconductor conducting after the metal-oxide-semiconductor threshold value, because constant current source charging speed and soft start capacitor velocity of discharge balance, soft start capacitor constantly provides to metal-oxide-semiconductor and drives compensation, realizes starting normal; Described self-oscillation anti exciting converter enters after the stable state, and constant current source charging speed and the soft start capacitor velocity of discharge are kept balance, and soft start continues to provide the driving compensation to metal-oxide-semiconductor, realizes the stable state operate as normal.
Referring to Fig. 4, be self-oscillation flyback converter first embodiment of band constant-current source soft starting circuit of the present invention.In the present embodiment one, adopt pulse frequency modulation circuit 13 as the Drive and Control Circuit of converter, the realization circuit of present embodiment mainly comprises following part: input filter circuit 11, band constant-current source soft starting circuit 12, pulse frequency modulation circuit 13, main power circuit 14, accessory power supply 15, output filter circuit 16, voltage stabilizing circuit 17, wherein input filter circuit 11, pulse frequency modulation circuit 13, main power circuit 14, accessory power supply 15, output filter circuit 16, the circuit structure of voltage stabilizing circuit 17 is identical with the circuit structure of circuit shown in Figure 2 in the background technology, and it is different that present embodiment and the difference of circuit shown in Figure 2 are that the circuit of the band constant-current source soft starting circuit 12 of present embodiment and circuit shown in Figure 2 is formed structure:
In the present embodiment, the main power tube in the main power circuit 14 adopts metal-oxide-semiconductor TR1, and main transformer adopts transformer T1, and transformer T1 includes former limit winding P1, output winding P2 and positive feedback winding P3.
Band constant-current source soft starting circuit 12 comprises constant-current source D1A, the first divider resistance R13, the second divider resistance R14, starts capacitor C 9.The anode of constant-current source D1A connects power input, the negative electrode of constant-current source D1A is connected to the power supply reference edge of self-oscillation anti exciting converter successively by the described first divider resistance R13 and the second divider resistance R14, described startup capacitor C 9 is in parallel with the series arm of the described first divider resistance R13 and the second divider resistance R14, and the tie point of the described first divider resistance R13 and the second divider resistance R14 is connected with the grid of described main power tube.Introduce the operation principle of this circuit below in detail:
The startup stage: when inserting input voltage, voltage charges the elapsed time through constant-current source to starting capacitor C 9
(U wherein
ThStartup thresholding for metal-oxide-semiconductor TR1, C is for starting the capacity of capacitor C 9, i is the constant current of constant-current source D1A service area) back starts the threshold voltage that capacitor C 9 voltages reach metal-oxide-semiconductor TR1, realize the start soft start function, before the formal foundation of output voltage, it is unstable state period, starting capacitor C 9 provides energy by the first divider resistance R13 to metal-oxide-semiconductor TR1 on the one hand, constant-current source D1A in time provides energy for starting capacitor C 9 on the other hand, select for use suitable constant-current source D1A namely can satisfy and start the energy balance that capacitor C 9 discharges and recharges, owing to start the energy compensating of capacitor C 9, make positive feedback winding P3 only need few energy just can finish self-oscillation process, thereby avoided the generation of batch (-type) vibration, it is normal that product is started.
Normal work stage: when input voltage variation or output loading variation, positive feedback winding P3 coupling energy changes, because it is fair for the energy that starts capacitor C 9 and provide to start energy that capacitor C 9 provides for the driving of metal-oxide-semiconductor TR1 by the first divider resistance R13 and constant-current source D1A, metal-oxide-semiconductor TR1 drives and is effectively compensated, positive feedback winding P3 coupling energy is required to reduce greatly, guarantee that positive feedback winding P3 self-oscillation is normal, improved the stability of product output voltage under different input voltages and different loads condition.Table seven is that PW4805D, power are the supply convertor of 3W for model, after constant-current source D1A adopts the constant-current source of 0.5mA, start the magnitude of voltage of capacitor C 9 under different input voltages and loading condition, contrast table two, table four, after adopting the technology of the present invention, the voltage that starts on the capacitor C 9 is basicly stable, and excursion is 2.4V only, has avoided the metal-oxide-semiconductor that resistance R 10 value differences cause in the former scheme to drive overcompensation and undercompensation.
Table seven
Pulse frequency modulation circuit 13 comprises: resistance R 6, resistance R 9, resistance R 11, resistance R 111, capacitor C 5, capacitor C 6, capacitor C 12, NPN type triode TR2, positive-negative-positive triode TR3.Capacitor C 6 is connected successively with resistance R 11, resistance R 111, resistance R 6, and a termination of series circuit is gone into the end of the same name of positive feedback winding P3, and the other end inserts the collector electrode of triode TR2.Capacitor C 5 is in parallel with resistance R 9, and a termination of parallel-current is gone into the base stage of triode TR2, and the other end inserts the collector electrode of triode TR3.Capacitor C 12 is in parallel with resistance R 111, and a termination of parallel circuits is gone into the emitter of three utmost point TR3, and the other end inserts the base stage of three utmost point TR3.Its operation principle is: positive feedback winding P3, capacitor C 6, resistance R 11 branch roads constitute the self-oscillation loop by being coupled with the former secondary of main power transformer T1, and control metal-oxide-semiconductor TR1 conducting is turn-offed; Electric current loop resistance R 5 branch roads, Voltage loop optocoupler OC1 branch road make product output normal by by triode TR2, the two-tube Drive and Control Circuit by-pass cock of triode TR3 pipe conducting duty ratio simultaneously.
Below other two kinds of embodiment are briefly described, band constant-current source soft starting circuit part wherein only is shown, the connection of other parts is identical with circuit shown in Figure 4.
Fig. 5 is the band constant-current source soft starting circuit part of the embodiment of the invention two, its difference with embodiment one is to have connected between the constant-current source D1A and power input in the band constant-current source soft starting circuit of present embodiment and is used for the current-limiting resistance R1A of restriction maximum current, this resistance can limit the start-up circuit maximum current, reduces the dividing potential drop at constant-current source two ends simultaneously.
Fig. 6 is the band constant-current source soft starting circuit part of the embodiment of the invention three, the difference of circuit shown in itself and the embodiment two only is that the on-position of the current-limiting resistance R1A that is used for the restriction maximum current in the band constant-current source soft starting circuit of present embodiment changes, between the negative electrode that current-limiting resistance R1A is connected described constant-current source D1A and the tie point of the first divider resistance R13 and startup capacitor C 9
Need to prove that above-mentioned constant-current source can be by the multiple mode of forming, it can be constant-current source parallel form of the prior art, as Figure 13; The constant-current source that constant-current source of the prior art and triode, voltage-stabiliser tube, resistance are composited, its constant current is output as Io=(V as Figure 14
2D-V
BE1)/R; Can also be the constant-current source that triode of the prior art and resistance constitute, as Figure 15, its constant current output Io=V
Be/ R
505Etc..
Except several enforcement circuit of above-mentioned explanation; industry technical staff can associate naturally for example by above description and accompanying drawing other be equal to application scheme; for example the Drive and Control Circuit of converter adopts as among Figure 16; by triode TR2; resistance R 6; the single tube Drive and Control Circuit that capacitor C 5 and resistance R 9 are formed replaces the pulse frequency modulation circuit in above-described embodiment etc.; for those skilled in the art; under the prerequisite that does not break away from the principle of the invention, the present invention is carried out some improvement and modification falls in the protection range of claim of the present invention.
Claims (5)
1. self-oscillation anti exciting converter, direct-flow input signal are exported direct current signal through behind input filter circuit, main power circuit and the output filter circuit successively, and main power circuit comprises main power tube and main transformer; The direct current signal of described output carries out negative feedback by voltage stabilizing circuit, isolation optocoupler and Drive and Control Circuit to main power tube successively and controls to realize stable output, it is characterized in that: also comprise the soft starting circuit of being with constant-current source, this soft starting circuit is connected between the output and described Drive and Control Circuit of described input filter circuit.
2. self-oscillation anti exciting converter according to claim 1 is characterized in that: the soft starting circuit of described band constant-current source comprises constant-current source (D1A), first divider resistance (R13), second divider resistance (R14) and starts electric capacity (C9); The anode of described constant-current source (D1A) is connected to the power input of self-oscillation anti exciting converter, the negative electrode of described constant-current source (D1A) is connected to the power supply reference edge of self-oscillation anti exciting converter successively by described first divider resistance (R13) and second divider resistance (R14), described startup electric capacity (C9) is in parallel with the series arm of described first divider resistance (R13) and second divider resistance (R14), and the tie point of described first divider resistance (R13) and second divider resistance (R14) is connected with the grid of described main power tube.
3. self-oscillation anti exciting converter according to claim 2, it is characterized in that: the soft starting circuit of described band constant-current source also comprises current-limiting resistance (R1A), and the anode of described constant-current source (D1A) is connected to the power input of self-oscillation anti exciting converter by described current-limiting resistance (R1A).
4. self-oscillation anti exciting converter according to claim 2, it is characterized in that: the soft starting circuit of described band constant-current source also comprises current-limiting resistance (R1A), and described current-limiting resistance (R1A) is connected negative electrode and described first divider resistance (R13) of described constant-current source (D1A) and starts between the tie point of electric capacity (C9).
5. according to each described self-oscillation anti exciting converter of claim 1 to 4, it is characterized in that: described constant-current source (D1A) is single constant-current source, or constant-current source parallel form, or the constant-current source that is composited of constant-current source and triode, voltage-stabiliser tube, resistance, or the constant-current source that constitutes of triode and resistance.
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| CN201210026265XA CN103248238A (en) | 2012-02-07 | 2012-02-07 | Ringing choke converter |
| PCT/CN2012/074151 WO2013117049A1 (en) | 2012-02-07 | 2012-04-16 | Self-oscillatory flyback converter |
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| CN106026712A (en) * | 2016-07-15 | 2016-10-12 | 深圳南云微电子有限公司 | Secondary-side control method and secondary-side control circuit of switching power supply |
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| CN109245513A (en) * | 2018-11-09 | 2019-01-18 | 深圳南云微电子有限公司 | A kind of start-up circuit |
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| US10338620B2 (en) | 2017-11-15 | 2019-07-02 | Infineon Technologies Ag | Feedback circuit for regulation loops |
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