CN101783595B - Overpower compensating method and device for wide voltage-input flyback power supply - Google Patents
Overpower compensating method and device for wide voltage-input flyback power supply Download PDFInfo
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Abstract
The invention relates to an overpower compensating method and an overpower compensating method for the wide voltage-input flyback power supply. The device comprises a flyback transformer of a flyback power supply, an OPP overpower compensating circuit and a PUM control IC serving as the flyback power supply. The method and the device are characterized in that: a winding is arranged on a primary side of the transformer, one end of the winding used as an unlike end is connected with a primary side reference ground, while the other end used as a like end transmits the voltage, which is generated by coupling, to an OPP overpower protection and detection functional end CS of the PUM control IC serving as the flyback power supply by the OPP overpower compensating circuit to perform the OPP overpower compensation. The method and the device can make an overpower protection point of a wide power supply (which inputs a 90-264 Vrms alternating current) closer and the OPP overpower compensating circuit does not work at a light load, which means the OPP compensating power has no power loss when a light load is output, so the method and the device can be applied to a flyback type wide-range power supply with low requirements on standby power consumption, the use is convenient and safe and the damages of parts, such as a switch MON tube, caused by output overload or short circuit are also reduced simultaneously.
Description
Technical field
The present invention relates to a kind of method and device of flyback power supply Overpower compensating of wide voltage input, because compensation circuit is turned off during underloading, not power consumption itself is so can be applicable in the middle of the low-down liquid crystal display product flyback power supply of standby power requirement.
Background technology
Present most of liquid crystal display product power supply adopts the reverse exciting topological framework usually; And input voltage adopts 90Vrms-264Vrms wide power mode to design usually; During in order to ensure output overloading or short circuit; The power supply part is not damaged or does not produce safety and draws the trouble problem, can be designed with overpower protection (OPP) function on the power panel usually, and present most of flyback power supply overpower protection is just like two kinds of Fig. 1 and Fig. 3.
Fig. 1 overpower protection loop is by Rs, R901, and C901 forms; Whether the current maxima that flows through through detecting Rs resistance has the inner OPP overpower protection of the PWM of reaching IC point to determine whether turning off PWM IC output; This overpower protection circuit is a kind of circuit that does not adopt any high-low pressure Overpower compensating, is input as between the 90Vrms-264Vrms at power supply, and the big capacitor C 903 voltage Vc903 voltage differences of power frequency filtering are very big; As: during the 90Vrms input voltage, Vc903 voltage is about 120V; And during 264Vrms during input voltage, Vc903 voltage is about 370V, because output overpower protection point Popp is big or small relevant with Vc903*u* (Ip1+Ip2)/2 relational expression; (the Maximum Power Output when Popp represents output overloading; Vc903 representes big capacitor C 903 average voltages of power frequency filtering, and is relevant with the input ac voltage size; As shown in Figure 2, when Ip1 representes that Q901 MOS switching tube is opened, flow through the electric current of Rs resistance, Ip2 representes that the Q901 metal-oxide-semiconductor turn-offs the electric current that flows through Rs resistance before; U representes T901 transformer conversion efficiency<b ><i >),</i></b>Wherein: (Vrs representes the voltage that detects on the Rs resistance to Vc903=Lp* (Ip2-Ip1)/Ton (Lp indication transformer primary side Np1 winding sensibility reciprocal, Ton represents Q901 MOS switching tube ON time) Ip2=Vrs/Rs; Rs representes the Rs resistance value), 0 ≦ Ip1<ip2, when Ip1=0, transformer work gets into the discontinuous mode operating state; When 0<ip1<during Ip2; Transformer work continuous mode operating state; And when Vrs=Ip2*Rs carried out through R901 resistance and C901 electric capacity that resultant voltage is greater than PWM IC CS end internal protection magnitude of voltage after the LPF, PWM IC inside just began to do the OPP overpower protection and moves.Can know from top relational expression and explanation: voltage Vc903 on the difference of flyback power supply OPP overpower protection point size and input voltage protection point when 90Vrsm-264Vrms and the big electric capacity of C903 power frequency filtering, the sensibility reciprocal of transformer T901 primary side Np1 winding and the isallobaric device parameter of transformer transformation efficiency, Rs current sense resistance; R901 resistance is relevant with the RC low-pass filter circuit that C901 electric capacity is formed; If these parameter designing are reasonable inadequately, OPP will occur and cross the defeated rate protection point set point that departs from objectives, at present in the middle of these parameters; Vc903 has the greatest impact at wide voltage source on the big capacitor C 903 of power frequency filtering; Vc903 is the 370V120V=3.08 of input during 90Vrms during power input voltage 264Vrms, and promptly 3.08 times, overpower protection point greatly in the time of usually can be than input 90Vrms when therefore importing 264Vrms; As: the design of overpower protection point is at 40W during input 90Vrms; Then the overpower protection point becomes 60W when 264Vrms, when therefore design does not have the flyback power supply electricity of OPP compensation, enough design margins will be arranged to its inverse-excitation type transformer and MOS switching tube; When output overloading or short circuit; Also not reaching full at transformer closes and before switch MOS pipe Q901 Ids drain electrode end electric current also do not reach the specification maximum, PWM IC must begin to do OPP protection action, draws trouble to guarantee that the power supply part is not damaged or does not produce safety; And design margin increases and possibly increase by design cost; Therefore and because input 90Vrsm differs greatly to 264Vrms OPP overpower protection point, also increased the power supply design difficulty, also caused parts such as causing switch MOS pipe Q901 because of output short-circuit or overload damage to occur simultaneously easily.
Fig. 2 overpower protection loop is by Rs; R901; C901, R912 forms, and wherein R912 is connected between big electric capacity anode of C903 power frequency filtering and the IC901 OPP overpower protection measuring ability end (CS end); As wide power high-low pressure OPP Overpower compensating circuit; At input voltage is that big capacitor C 903 voltages of power frequency are about 120V in the 90Vrms, and IC901 OPP overpower protection measuring ability end this moment (CS end) obtains less OPP Overpower compensating, offset current I=120V/ (R905+R901+Rs); At input voltage is that big capacitor C 903 voltages of power frequency are about 370V in the 264Vrms, and IC901 OPP overpower protection measuring ability end this moment (CS end) obtains bigger OPP Overpower compensating, offset current I=370V/ (R905+R901+Rs); Many more through the high more resultant OPP Overpower compensating of power supply input ac voltage; Make that to be input as between the 90Vrms-264Vrms OPP overpower protection point more approaching; Because compensating resistance R912 is connected on power frequency capacitor C 903 anodes and IC901 CS low-pressure end; As input voltage 264Vrms, direct voltage is about 370V on the power frequency electric capacity, then the ohmically power consumption P=370V*370V/R912 of R912 this moment; Adopt this kind overpower to mend to taste device, when R912 resistance during less than 1M, excessive OPP Overpower compensating can appear in circuit; It is better that the R905 value is set in 1M left and right sides OPP Overpower compensating effect, but loss this moment power consumption on R912 resistance is bigger, is about 0.136mW, can't use on the lower liquid crystal display product of stand-by power consumption.The R912 resistance value the not enough problem of OPP Overpower compensating occurs greater than more than the 2M, and when promptly power supply was imported between 90Vrms-264Vrms, power supply output overpower protection point began to occur bigger difference.
Summary of the invention
In order to overcome the deficiency of above-mentioned technology; The present invention improves existing flyback power supply Overpower compensating circuit; A kind of method of flyback power supply Overpower compensating of wide voltage input is provided; The inverse-excitation type transformer that comprises flyback power supply; OPP Overpower compensating circuit, and as flyback power supply PWM control IC, it is characterized in that: the inverse-excitation type transformer primary at said flyback power supply increases a winding; And with this winding one end as different name termination inverse-excitation type transformer primary with reference to ground, and the other end is done OPP Overpower compensating through OPP Overpower compensating circuit transmission to the OPP overpower protection measuring ability end CS as flyback power supply PWM control IC with the voltage that is coupled out as end of the same name; Describedly comprise pulse-width modulation output function end Gate as flyback power supply PWM control IC, PWM IC function of supplying power end Vcc, OPP output overpower protection measuring ability end CS, PWM IC detects output voltage feedback end FB, and PWM IC connects with reference to ground end GND; The inner that said PWM IC detects output voltage feedback end FB is connected with a pull-up resistor Rfb one end, and another termination of pull-up resistor Rfb one reference voltage V ref; When the voltage of OPP output overpower protection measuring ability end CS detects the voltage of output voltage feedback end FB greater than PWM IC, pulse-width modulation output function end Gate output low level; Said PWM IC detects output voltage feedback end FB voltage and the flyback power supply output band relation of carrying is: when being output as underloading; PWM IC detects output voltage feedback end FB voltage and reduces to lower voltage quasi position; And the OPP of PWM IC output overpower protection measuring ability end CS detects less voltage, and this moment, the pulse-width modulation output function end Gate of PWM IC exported less pulse width modulation duty; And when output year change is heavy; PWM IC detects output voltage feedback end FB voltage and rises to the higher voltage position; This moment, the pulse-width modulation output function end Gate output pulse width modulation duty cycle of PWM IC increased, and the OPP of PWM IC output overpower protection measuring ability end CS detects bigger voltage; When output overloading; PWM IC detects output voltage feedback end FB voltage and rises to higher voltage; This moment, the pulse-width modulation output function end Gate output pulse width modulation duty cycle of PWM IC continued to increase; And the OPP of PWM IC output overpower protection measuring ability end CS detects voltage when reaching the OPP protection point reference voltage of PWM IC inner setting, and PWM IC just begins to do the OPP overpower protection.
Another object of the present invention provides a kind of device of flyback power supply Overpower compensating of wide voltage input; It adopts following scheme to realize: the inverse-excitation type transformer T901 that comprises flyback power supply; OPP Overpower compensating circuit; And as flyback power supply PWM control IC, it is characterized in that: described inverse-excitation type transformer T901 comprises:
One primary side Np1 winding, its end p11 of the same name is connected with the big capacitance cathode end of C903 power frequency, and different name end p12 is connected with the drain electrode of MOS switching tube Q901;
One primary side Np2 winding, its end of the same name is connected with reference to ground with inverse-excitation type transformer T901 primary side, and the different name end is connected with the Vcc power supply circuits;
One primary side NP3 winding, its different name end p32 connect inverse-excitation type transformer T901 primary side with reference to ground, and the other end is connected with OPP Overpower compensating circuit as end p31 of the same name;
Primary side Ns1, Ns2 ... The Nsn winding, its termination inverse-excitation type transformer T901 primary side of the same name is with reference to ground, and the different name end is connected with output rectification circuit;
Said OPP Overpower compensating circuit output end be connected as flyback power supply PWM control IC, described pulse-width modulation output function end Gate as flyback power supply PWM control IC is connected with the grid of MOS switching tube Q901;
Describedly comprise pulse-width modulation output function end Gate at least as flyback power supply PWM control IC, PWM IC function of supplying power end Vcc, OPP output overpower protection measuring ability end CS, PWM IC detects output voltage feedback end FB, and PWM IC connects with reference to ground end GND;
The inner that said PWM IC detects output voltage feedback end FB is connected with a pull-up resistor Rfb one end, and another termination of pull-up resistor Rfb one reference voltage V ref; When the voltage of OPP output overpower protection measuring ability end CS detects the voltage of output voltage feedback end FB greater than PWM IC, pulse-width modulation output function end Gate output low level; Said PWM IC detects output voltage feedback end FB voltage and the flyback power supply output band relation of carrying is: when being output as underloading; PWM IC detects output voltage feedback end FB voltage and reduces to lower voltage quasi position; And the OPP of PWM IC output overpower protection measuring ability end CS detects less voltage, and this moment, the pulse-width modulation output function end Gate of PWM IC exported less pulse width modulation duty; And when output year change is heavy; PWM IC detects output voltage feedback end FB voltage and rises to the higher voltage position; This moment, the pulse-width modulation output function end Gate output pulse width modulation duty cycle of PWM IC increased, and the OPP of PWM IC output overpower protection measuring ability end CS detects bigger voltage; When output overloading; PWM IC detects output voltage feedback end FB voltage and rises to higher voltage; This moment, the pulse-width modulation output function end Gate output pulse width modulation duty cycle of PWM IC continued to increase; And the OPP of PWM IC output overpower protection measuring ability end CS detects voltage when reaching the OPP protection point reference voltage of PWM IC inner setting, and PWM IC just begins to do the OPP overpower protection.
The present invention is skillfully constructed; Circuit structure is simple; Through increasing this OPP Overpower compensating circuit, make power supply product more meet the requirement of wide power product design specification (PDS), make product safer in use; Simultaneously also can reduce or cause the problem of damage parts such as MOS switching tube in short-term, effectively prolong product useful life because of output overloading.
Description of drawings
Fig. 1 is that the input 90Vrms-264Vrms inverse-excitation type wide power of convention does not adopt any OPP Overpower compensating circuit to have the flyback power supply in overpower protection loop.
Fig. 2 is a current waveform figure under the flyback power supply Q901 metal-oxide-semiconductor perfect condition.
Fig. 3 is that the input 90Vrms-264Vrms inverse-excitation type wide power of convention uses a power resistor R912 to be connected to the sketch map that the big electric capacity anode of C903 power frequency filtering and PWM IC OPP overpower protection measuring ability end (CS end) are done the OPP Overpower compensating.
Fig. 4 is the circuit structure principle schematic of the embodiment of the invention.
Fig. 5 is the circuit theory sketch map that embodiment of the invention PWM IC detects the output voltage feedback end.
Embodiment
Present embodiment provides a kind of method of flyback power supply Overpower compensating of wide voltage input; The inverse-excitation type transformer that comprises flyback power supply; OPP Overpower compensating circuit; And, it is characterized in that as flyback power supply PWM control IC: increase a winding in the inverse-excitation type transformer primary of said flyback power supply, and with this winding one end as different name termination inverse-excitation type transformer primary with reference to ground; And the other end as end of the same name will with transformer Np1 winding coupled, and the voltage that is coupled out is done the OPP Overpower compensating through OPP Overpower compensating circuit transmission to the OPP overpower protection measuring ability end CS as flyback power supply PWM control IC.In present embodiment, the number of turns of said winding is a circle.
Describedly comprise pulse-width modulation output function end Gate at least as flyback power supply PWM control IC, PWM IC function of supplying power end Vcc, OPP output overpower protection measuring ability CS, PWM IC detects output voltage feedback end FB, and PWM IC connects with reference to ground end GND.The inner that said PWM IC detects output voltage feedback end FB is connected with a pull-up resistor Rfb one end, and another termination of pull-up resistor Rfb one reference voltage V ref; When the voltage of OPP output overpower protection measuring ability end CS detects the voltage of output voltage feedback end FB greater than PWM IC, pulse-width modulation output function end Gate output low level; Said PWM IC detects output voltage feedback end FB voltage and the flyback power supply output band relation of carrying is: when being output as underloading; PWM IC detects output voltage feedback end FB voltage and reduces to lower voltage quasi position; And the OPP of PWM IC output overpower protection measuring ability end CS detects less voltage, and this moment, the pulse-width modulation output function end Gate of PWM IC exported less pulse width modulation duty; And when output year change is heavy; PWM IC detects output voltage feedback end FB voltage and rises to the higher voltage position; This moment, the pulse-width modulation output function end Gate output pulse width modulation duty cycle of PWM IC increased, and the OPP of PWM IC output overpower protection measuring ability end CS detects bigger voltage; When output overloading; PWM IC detects output voltage feedback end FB voltage and rises to higher voltage; This moment, the pulse-width modulation output function end Gate output pulse width modulation duty cycle of PWM IC continued to increase; And the OPP of PWM IC output overpower protection measuring ability end CS detects voltage when reaching the OPP protection point reference voltage of PWM IC inner setting, and PWM IC just begins to do the OPP overpower protection.
As shown in Figure 4 in addition; This enforcement provides a kind of device of flyback power supply Overpower compensating of wide voltage input; The inverse-excitation type transformer T901 that comprises flyback power supply; OPP Overpower compensating circuit, and as flyback power supply PWM control IC, it is characterized in that: described inverse-excitation type transformer T901 comprises:
One primary side Np1 winding, its end p11 of the same name is connected with the big capacitance cathode end of C903 power frequency, and different name end p12 is connected with the drain electrode of MOS switching tube Q901;
One primary side Np2 winding, its end of the same name is connected with reference to ground with inverse-excitation type transformer T901 primary side, and the different name end is connected with the Vcc power supply circuits;
One primary side NP3 winding, its different name end p32 connect inverse-excitation type transformer T901 primary side with reference to ground, and the other end is connected with OPP Overpower compensating circuit as end p31 of the same name;
Primary side Ns1, Ns2 ... The Nsn winding, its termination inverse-excitation type transformer T901 primary side of the same name is with reference to ground, and the different name end is connected with output rectification circuit;
Said OPP Overpower compensating circuit output end be connected as flyback power supply PWM control IC, described pulse-width modulation output function end Gate as flyback power supply PWM control IC is connected with the grid of MOS switching tube Q901.
What deserves to be mentioned is, for device of the present invention can well be applied in the middle of the power supply of the very low liquid crystal display product of standby power requirement.Described OPP Overpower compensating inside circuit is provided with the switching tube that a group transistor (Q902, Q903) is done OPP Overpower compensating circuit; Determine whether to do OPP Overpower compensating circuit through detecting PWM IC FB terminal voltage size and open or turn-off; When power supply is output as underloading; OPP Overpower compensating circuit is turned off through this transistor (Q902, Q903), and the Overpower compensating circuit stops the OPP overpower protection measuring ability end CS of PWM IC is done wide power interchange input high-low pressure Overpower compensating; When power supply is output as heavy duty; OPP Overpower compensating circuit is opened through transistor (Q902, Q903), and OPP Overpower compensating circuit begins the OPP overpower protection measuring ability end CS of PWM IC is done wide power interchange input high-low pressure Overpower compensating.
In order to let those skilled in the art can clearly understand the present invention, some control principles of present embodiment circuit are carried out concrete introduction below in conjunction with Fig. 4:
One, it is following how to let the OPP compensating circuit open the operation principle of still turn-offing during flyback power supply output weight: when power supply output with load when reducing, electric power output voltage Vout increases, because of V1=Vout * R904/ (R903+R904); So V1 voltage increases, because of V1 is the R end that is input to TL431, and the R end is the anode of TL431 internal error amplifier; So TL431 internal transistor base current Ib1 increases,, increase so flow through IC902 optocoupler internal illumination diode electric current I f because of If=Ib1*K (K is a TL431 internal transistor multiplication factor); Because of IC902 optocoupler Ic1=If*CTR (CTR is that the inner photoelectricity of optocoupler transforms transmission ratio), so IC902 optocoupler output current Ic1 increases; Because of the FB end of optocoupler output (C end) and IC901PWM IC is connected, with reference to figure 5-the inner FB end of IC901 PWM IC is connected with a pull-up resistor Rfb one end, and another termination one reference voltage of pull-up resistor Rfb; Its Vfb=Vref-Ic1*Rfb, thus PWM IC FB terminal voltage Vfb reduce, because of Vg=Vfb*R909/ (R909+R910); So Q902 switching tube grid Vg voltage reduces, carry when lighter when power supply output, Q902 switching tube grid voltage Vg is just more little; And when Vg voltage during less than Q902 switching tube threshold voltage Vgs (th); The Q902 switching tube turn-offs, and this moment, the Q903 switching tube also was turned off, and promptly OPP Overpower compensating circuit quits work.When power supply output with load when increasing, electric power output voltage Vout reduces, because of V1=Vout * R904/ (R903+R904); So V1 voltage reduces, because of V1 is the R end that is input to TL431, and the R end is the anode of TL431 internal error amplifier; So TL431 internal transistor base current Ib1 reduces, and because of If=Ib1*K (K is a TL431 internal transistor multiplication factor), reduces so flow through IC902 optocoupler internal illumination diode electric current I f; Because of IC902 optocoupler Ic1=If*CTR (CTR is that the inner photoelectricity of optocoupler transforms transmission ratio), so IC902 optocoupler output current Ic1 reduces; Because of the FB end of optocoupler output (C end) and IC901PWM IC is connected, with reference to figure 5-the inner FB end of IC901 PWM IC is connected with a pull-up resistor Rfb one end, and another termination one reference voltage of pull-up resistor Rfb; Its Vfb=Vref-Ic1*Rfb, thus PWM IC FB terminal voltage Vfb increase, because of Vg=Vfb*R909/ (R909+R910); So Q902 switching tube grid Vg voltage increases, carry when heavy more when power supply output, Q902 switching tube grid voltage Vg is just big more; And when Vg voltage during greater than Q902 switching tube threshold voltage Vgs (th); The Q902 switching tube is opened, and this moment, the Q903 switching tube also was opened, and promptly OPP Overpower compensating circuit is started working.
Two, OPP Overpower compensating operation principle:
Because inverse-excitation type wide power OPP overpower protection point is common: when input 90Vrms alternating voltage, OPP protection point is less, when input 264Vrms alternating voltage; OPP protection point is bigger; Therefore hope when being input as 90Vrms, obtain less OPP compensation, and when being input as 264Vrms; Obtain big OPP compensation; Compensate when big more, output overpower protection point can become low more, therefore can make that the OPP overpower protection point of power input voltage between 90Vrms-264Vrms is more approaching through R906/R901 resistance size in the adjustment OPP compensating circuit; Concrete operation principle is following: it is 1 circle Np3 winding that transformer T901 is increased by a number of turns, and Np1 winding p11 end is end of the same name with Np3 winding p31 end; And Np1 winding p12 end holds relative p11/p31 end to be the different name end with Np3 winding p32, that is: when MOS switching tube Q901 drain electrode end is opened, T901 transformer Np1 winding p11 end is for just, and the p12 end is for bearing; Np3 winding p31 end is for just, and the p32 end is for bearing.The Np3 winding is coupled at this moment, and (Np3 representes the number of turns of Np3 winding to the Np1 winding to voltage Vnp3=Vc903*Np3/Np1=Vc903/Np1; Np1 representes the number of turns of Np1 winding; Vc903 representes the direct voltage on the big capacitor C 903 of power frequency); Np3 voltage that winding is coupled to transfers OPP Overpower compensating circuit and does the OPP Overpower compensating through R911 à D901 à Q903 à R906 to PWM IC CS end; When power input voltage is 90Vrms; The big capacitor C 903 voltage Vc903 of power frequency filtering are about about 120V; This moment, transformer T903 Np3 winding was coupled to voltage Vnp3=120V/Np1 (Np1 representes this winding number of turns); Hypothesis: Np1=50 encloses earlier; D901 forward conduction voltage Vf=0.7V, Q903 crystal guarantee adequate food and close conduction voltage drop Vce=0.3V, Rs=0.68
;, R911=10
Then this moment, PWM IC CS end obtained the OPP bucking voltage
△V1=(Vnp3-Vf-Vce)*(Rs+R901)/(R911+R906+R901+Rs)
=1.4V* (0.68+R901)/(10.68+R901+R906); When power input voltage is 264Vrms; The big capacitor C 903 voltage Vc903 of power frequency filtering are about about 370V; This moment, transformer T903 Np3 winding was coupled to voltage Vnp3=370V/Np1 (Np1 representes this winding number of turns), and then this moment, PWM IC CS end obtained the OPP bucking voltage
△V2=(Vnp3-Vf-Vce)*(Rs+R901)/(R911+R906+R901+Rs)
=6.4V* (0.68+R901)/(10.68+R901+R906); OPP Overpower compensating voltage was about 4.57 times when importing 90Vrms when △ V2/ △ V1=4.57 was power input voltage 264Vrms; Through adjustment R906 and R901 resistance size power input voltage OPP overpower protection point between 90Vrms-264Vrms is close again
Three, the effect of each part in the OPP Overpower compensating circuit:
R911 resistance is placed on D901 rectifier diode anode, has better EMI and suppresses effect;
The D901 diode plays rectified action in the middle of circuit;
C901/C904/C905 electric capacity is used as the assorted fast of filtering high frequency;
R907/R908 resistance is as the divider resistance between Q903 PNP transistor base and the emitter;
R910/R909 is a Q902MOS switching tube grid divider resistance;
R906 is adjustment OPP Overpower compensating resistance;
R901 is promptly as OPP Overpower compensating resistance, again and C901 electric capacity form the RC low-pass filter circuit and prevent that the assorted fast PWM of the interfering with IC CS between the Q901/Rs from holding;
Q902 and Q903 transistor are done the switching tube that control OPP compensating circuit is opened and turn-offed, and wherein: Q902 is the N-channel MOS pipe, and also available NPN transistor substitutes; Q903 is the PNP transistor, and also available P channel MOS tube substitutes.
The above is merely preferred embodiment of the present invention, and all equalizations of doing according to claim of the present invention change and modify, and all should belong to covering scope of the present invention.
Claims (5)
1. the method for the flyback power supply Overpower compensating of one kind wide voltage input; The inverse-excitation type transformer that comprises flyback power supply; OPP Overpower compensating circuit; And as flyback power supply PWM control IC; It is characterized in that: increase a winding in the inverse-excitation type transformer primary of said flyback power supply, and with this winding one end as different name termination inverse-excitation type transformer primary with reference to ground, and the other end is exported overpower protection measuring ability end (CS) through OPP output Overpower compensating circuit transmission to the OPP as flyback power supply PWM control IC with the voltage that is coupled out as end of the same name and is done the OPP Overpower compensating; Describedly comprise pulse-width modulation output function end (Gate) as flyback power supply PWM control IC; PWM IC function of supplying power end (Vcc); OPP exports overpower protection measuring ability end (CS), and PWM IC detects output voltage feedback end (FB), and PWM IC connects with reference to ground end (GND); The inner that said PWM IC detects output voltage feedback end (FB) is connected with a pull-up resistor (Rfb) end, and another termination one reference voltage (Vref) of pull-up resistor (Rfb); When the voltage of OPP output overpower protection measuring ability end (CS) detects the voltage of output voltage feedback end (FB) greater than PWM IC, pulse-width modulation output function end (Gate) output low level; Said PWM IC detects output voltage feedback end (FB) voltage and the flyback power supply output band relation of carrying is: when being output as underloading; PWM IC detects output voltage feedback end (FB) voltage and reduces to lower voltage quasi position; And the OPP of PWM IC output overpower protection measuring ability end (CS) detects less voltage, and this moment, the pulse-width modulation output function end (Gate) of PWM IC was exported less pulse width modulation duty; And when output year change is heavy; PWM IC detects output voltage feedback end (FB) voltage and rises to the higher voltage position; This moment, pulse-width modulation output function end (Gate) the output pulse width modulation duty cycle of PWM IC increased, and the OPP of PWM IC output overpower protection measuring ability end (CS) detects bigger voltage; When output overloading; PWM IC detects output voltage feedback end (FB) voltage and rises to higher voltage; This moment, pulse-width modulation output function end (Gate) the output pulse width modulation duty cycle of PWM IC continued to increase; And the OPP of PWM IC output overpower protection measuring ability end (CS) detects voltage when reaching the OPP protection point reference voltage of PWM IC inner setting, and PWM IC just begins to do the OPP overpower protection.
2. the method for the flyback power supply Overpower compensating of wide voltage input according to claim 1, it is characterized in that: the number of turns of said winding is a circle.
3. the device of the flyback power supply Overpower compensating of one kind wide voltage input; The inverse-excitation type transformer (T901) that comprises flyback power supply; OPP Overpower compensating circuit, and as flyback power supply PWM control IC, it is characterized in that: described inverse-excitation type transformer (T901) comprising:
One primary side Np1 winding, its end of the same name (p11) is connected with the big electric capacity of power frequency (C903) positive terminal, and different name end (p12) is connected with the drain electrode of MOS switching tube (Q901);
One primary side Np2 winding, its end of the same name is connected with reference to ground with inverse-excitation type transformer (T901) primary side, and the different name end is connected with the Vcc power supply circuits;
One primary side NP3 winding, its different name end (p32) connect inverse-excitation type transformer (T901) primary side with reference to ground, and the other end is connected with OPP Overpower compensating circuit as end of the same name (p31);
Primary side Ns1, Ns2 ... The Nsn winding, its termination inverse-excitation type transformer of the same name (T901) primary side is with reference to ground, and the different name end is connected with output rectification circuit;
Said OPP Overpower compensating circuit output end be connected as flyback power supply PWM control IC, described pulse-width modulation output function end (Gate) as flyback power supply PWM control IC is connected with the grid of MOS switching tube (Q901);
Describedly comprise pulse-width modulation output function end (Gate) at least as flyback power supply PWM control IC; PWM IC function of supplying power end (Vcc); OPP exports overpower protection measuring ability end (CS), and PWM IC detects output voltage feedback end (FB), and PWM IC connects with reference to ground end (GND);
The inner that said PWM IC detects output voltage feedback end (FB) is connected with a pull-up resistor (Rfb) end, and another termination one reference voltage (Vref) of pull-up resistor (Rfb); When the voltage of OPP output overpower protection measuring ability end (CS) detects the voltage of output voltage feedback end (FB) greater than PWM IC, pulse-width modulation output function end (Gate) output low level; Said PWM IC detects output voltage feedback end (FB) voltage and the flyback power supply output band relation of carrying is: when being output as underloading; PWM IC detects output voltage feedback end (FB) voltage and reduces to lower voltage quasi position; And the OPP of PWM IC output overpower protection measuring ability end (CS) detects less voltage, and this moment, the pulse-width modulation output function end (Gate) of PWM IC was exported less pulse width modulation duty; And when output year change is heavy; PWM IC detects output voltage feedback end (FB) voltage and rises to the higher voltage position; This moment, pulse-width modulation output function end (Gate) the output pulse width modulation duty cycle of PWM IC increased, and the OPP of PWM IC output overpower protection measuring ability end (CS) detects bigger voltage; When output overloading; PWM IC detects output voltage feedback end (FB) voltage and rises to higher voltage; This moment, pulse-width modulation output function end (Gate) the output pulse width modulation duty cycle of PWM IC continued to increase; And the OPP of PWM IC output overpower protection measuring ability end (CS) detects voltage when reaching the OPP protection point reference voltage of PWM IC inner setting, and PWM IC just begins to do the OPP overpower protection.
4. the device of the flyback power supply Overpower compensating of wide voltage input according to claim 3, it is characterized in that: the number of turns of described primary side NP3 winding is a circle.
5. the device of the flyback power supply Overpower compensating of wide voltage input according to claim 3; It is characterized in that: described OPP Overpower compensating circuit is provided with the switching tube that a group transistor (Q902, Q903) is done OPP Overpower compensating circuit; Detecting output voltage feedback end voltage swing through detecting PWM IC determines whether doing OPP Overpower compensating circuit and opens or turn-off; When power supply is output as underloading; OPP Overpower compensating circuit is turned off through its internal transistor (Q902, Q903), and the Overpower compensating circuit stops that the OPP output overpower protection measuring ability end (CS) of PWM IC is done wide power and exchanges input high-low pressure Overpower compensating; When power supply is output as heavy duty; OPP Overpower compensating circuit is opened through transistor (Q902, Q903), and this moment, OPP Overpower compensating circuit began the OPP output overpower protection measuring ability end (CS) of PWM IC is done wide power interchange input high-low pressure Overpower compensating.
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| TWI559666B (en) * | 2014-11-18 | 2016-11-21 | 立錡科技股份有限公司 | Flyback power converter, secondary side control circuit, and control method thereof |
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| DE102015114495A1 (en) * | 2015-08-31 | 2017-03-02 | Infineon Technologies Austria Ag | VOLTAGE CONVERTER AND VOLTAGE CONVERSION PROCESS |
| CN105322815A (en) * | 2015-11-26 | 2016-02-10 | 成都启臣微电子有限公司 | External adjustable overpower compensation circuit of switching power supply |
| CN105529683B (en) * | 2016-02-17 | 2018-01-02 | 深圳茂硕电子科技有限公司 | A kind of secondary overpower-protection circuit and Switching Power Supply |
| CN110971126B (en) * | 2018-09-29 | 2021-05-28 | 比亚迪半导体股份有限公司 | Switching power supply, control device thereof, loop compensation method and storage medium |
| CN111884512A (en) | 2020-03-18 | 2020-11-03 | 深圳市航嘉驰源电气股份有限公司 | Switching power supply, power adapter and charger |
| CN117277773B (en) * | 2023-09-27 | 2024-08-30 | 成都智融微电子有限公司 | Protection method, protection device, switching power supply, and computer-readable storage medium |
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