CN103856053A - Power supply controller with overpower protection function - Google Patents

Power supply controller with overpower protection function Download PDF

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Publication number
CN103856053A
CN103856053A CN201210514639.2A CN201210514639A CN103856053A CN 103856053 A CN103856053 A CN 103856053A CN 201210514639 A CN201210514639 A CN 201210514639A CN 103856053 A CN103856053 A CN 103856053A
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China
Prior art keywords
power
overpower
pulse width
electric
supply controller
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CN201210514639.2A
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CN103856053B (en
Inventor
邹明璋
蔡孟仁
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Leadtrend Technology Corp
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Leadtrend Technology Corp
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Abstract

A power supply controller can provide a pulse width modulation signal so as to control a power switch. The power supply controller comprises a pulse width modulation signal generator, a first oscillator, a second oscillator and an overpower detector. The pulse width modulation signal generator is used for generating pulse width modulation signals. The first oscillator is connected to the pulse width modulation signal generator in a coupled mode and can decide the switching period of the pulse width modulation signals. The second oscillator can be used for deciding overpower protection time. The overpower detector is used for detecting whether an overpower accident occurs or not. When the overpower accident continues for the overpower protection time, the pulse width modulation signals continue to turn off the power switch.

Description

There is the power-supply controller of electric of overpower protection
Technical field
The invention relates to the protection mechanism of power supply unit, espespecially about the overpower protection of switch type power supplying device.
Background technology
Power supply unit is the essential a kind of electronic installation of most electronic product, is used for battery or civil power, converts required by electronic product to and ask and have the power supply of specific standard.In numerous power supply units, switch type power supplying utensil has superior energy conversion efficiency and small and exquisite small product size, so welcome by power supply industry.
Power supply unit not merely just will meet output voltage/electric current and high energy conversion efficiency accurately, the protection mechanism also must possess many generation unusual conditions time.The general known protection mechanism of industry has overpower protection, overvoltage protection, overcurrent protection, crosses high temperature protection etc.
Printer or notebook computer often have high-power electrical energy demands of short time.Take printer as example, general printer may be to be in standby or to receive signal for a long time, only need to have generally or low power consumption very; But in the time of the printing operation of short time, just need to there is very high power consumption.For the cost of manufacture of economization power supply unit and reach this kind of special application, so in specification, power supply unit just has so-called normal power (normal power) and peak power (peak power), respectively the maximum admissible power stage of corresponding power supply in the time of normal running and ultra high power operation.Once the power output of power supply unit exceeds normal power, and such high-power output continued to cross when long-time, just can trigger overpower protection.For instance, in United States Patent (USP) numbering 7486493, just provide a kind of power supply unit with overpower protection.
In this specification, there is identical labeled elements or device, for thering is identical or element or the device of similar functions, structure or characteristic, for people in the industry can learn or know by inference with the instruction of this specification of tool, but uninevitable identical completely.For succinct cause, can repeat specification.
Summary of the invention
Embodiments of the invention disclose a kind of power-supply controller of electric, and a pulse width modulating signal can be provided, in order to control a power switch.This power-supply controller of electric includes a pulse width modulating signal generator, one first oscillator, one second oscillator and an overpower detector.This this pulse width modulating signal of pulse width modulating signal generator for generating.This first oscillator is coupled to this pulse width modulating signal generator, can determine a switch periods of this pulse width modulating signal.This second oscillator can be in order to determine the overpower protection time.Whether this overpower detector occurs in order to detect an overpower event.In the time that this overpower event continues to reach this overpower protection time, this pulse width modulating signal continues to close this power switch.
Accompanying drawing explanation
Fig. 1 shows a power supply unit of implementing according to the present invention.
Fig. 2 shows in one embodiment of this invention, cycle signal S cYCcycle frequency f cYCand clock signal S tIMERclock frequency f tIMER, to bucking voltage V cOMrelation.
Fig. 3 A display offset amount V oFFSETwith input power V iNthe relation of voltage.
Fig. 3 B display offset amount V oFFSETwith opening time T oNrelation.
[main element label declaration]
10 power supply unit 12 transformers
14 power switch 15 loads
16 building-out capacitor 18 operational amplifiers
20 power-supply controller of electric 22 oscillators
24 diode 26 resistance
28 resistance 30 comparators
31 pulse width modulation generator 32 protection modules
34 comparator 36 comparators
37 oscillator 38 OCP counters
40 gate 42 OPP counters
COM compensation end f cYCcycle frequency
F tIMERclock frequency I cSelectric current
PRM main winding (primary winding) R cScurrent sense resistor
S cYCcycle signal SEC secondary winding
S pWMpulse width modulating signal S tIMERclock signal
T oNopening time V cOMbucking voltage
V cOM-Hpredeterminated voltage V cOM-Lpredeterminated voltage
V cScurrent detection signal V cS-LIMITcurrent limiting signal
V iNinput power V oFFSETside-play amount
V oPPoverpower voltage V oUTout-put supply
V sLOPEslope-compensation voltage V tARtarget voltage
Embodiment
Fig. 1 shows a power supply unit 10 of implementing according to the present invention, and it has overpower protection and overcurrent protection.Although power supply unit 10 is a flyback (flyback) power supply changeover device (powerconverter), the present invention is not limited to this, and the present invention is applicable to any power supply unit.Similarly be reducing transformer (Buck converter) or stepup transformer (booster).
Input power (line power source) V iNcan be produced through over commutation by an electric main, its voltage may be up to 280V.Power switch 14 is controlled the electric current I of main winding (primarywinding) PRM of the transformer 12 of flowing through cS, it is by current sense resistor R cS, convert current detection signal V to cS.Current detection signal V cSapproximately represent electric current I cS.In the time of power switch 14 conducting, input power V iNtransformer 12 energy storage are increased.In the time that power switch 14 is closed, transformer 12 is released energy by secondary winding (secondary winding) SEC, sets up out-put supply V oUT, load 15 is powered.According to out-put supply V oUTwith target voltage V tARdifference, operational amplifier 18 drives building-out capacitor 16, on compensation end COM, sets up out bucking voltage V cOM.Power-supply controller of electric 20 is according to bucking voltage V cOM, produce pulse width modulating signal S pWM, it is switch power switch 14 periodically.Power-supply controller of electric 20 provides a loop, expects out-put supply V oUTbe stable at target voltage V tAR.For instance, higher bucking voltage V cOM, pulse width modulating signal S pWMhave the larger work period (duty cycle), transformer 12 is to out-put supply V oUTthe power output of transmission is higher.Because out-put supply V oUTapproximately be stable at target voltage V tAR, high bucking voltage V cOM, also meaned out-put supply V simultaneously oUTthe load 15 of powering is heavier.
Power supply unit 10 can be implemented by a secondary side control mode (secondary side control), also can use primary side control mode (primary side control) to implement.Secondary side control mode is by the message of secondary side, passes to primary side control by optical coupling element.And primary side control does not have optical coupling element, direct-detection is also controlled the cross-pressure on auxiliary winding.
In one embodiment, power-supply controller of electric 20 has oscillator 22, and it provides cycle signal S cYC, periodically by pulse width modulation generator 31, make pulse width modulating signal S pWMfor " 1 " in logic, open power switch 14.Cycle signal S cYCdetermine pulse width modulating signal S pWMswitch periods in, opening time T oNthe starting point of (logic is " 1 ").In other embodiments, cycle signal S cYCcan determine cycle signal S cYCcan determine pulse width modulating signal S pWMin, shut-in time T oFFthe starting point of (logical zero).A switch periods includes an opening time T oNan and shut-in time T oFF.Bucking voltage V cOMthrough diode 24 step-downs, after resistance 26 and 28 dividing potential drops, carry out Limited Current detection signal V cSpeak value.As current detection signal V cSrise to bucking voltage V cOMdeduction falls slope-compensation voltage V sLOPEtime, comparator 30, by pulse width modulation generator 31, makes pulse width modulating signal S pWMfor " 0 " in logic, close power switch 14, determine shut-in time T oFFbeginning.In one embodiment, slope-compensation voltage V sLOPEalong with opening time T oNincrease and increase.
In protection module 32, overcurrent protection and overpower protection are provided.Whether comparator 34 and 36 respectively detection of excessive current event and overpower event occurs.Oscillator 37 is independent of oscillator 22, and clock signal S is provided tIMER, for protection module 32 timing used.
Relatively current detection signal V of comparator 34 cSan and current limiting signal V cS-LIMIT.As current detection signal V cSwith a side-play amount V oFFSETand, if exceed current limiting signal V cS-LIMITtime, comparator 34 assert that overcurrent event starts to occur.OCP counter 38, from overcurrent event starts to occur, starts counting.OCP counter 38 is with clock signal S tIMERas clock, calculate overcurrent event and whether continue to reach the overcurrent protection time.If overcurrent event does not continue to reach the overcurrent protection time and just disappeared, OCP counter 38 just resets to 0, and stops counting.For instance, counter 38 finds that overcurrent event continues to reach clock signal S tIMERwhen defined 100 clocks, counter 38 just passes through gate 40, the pulse width modulating signal S that pulse width modulation generator 31 is exported pWMbe fixed on " 0 " in logic, continue to close power switch 14, to reach overcurrent protection.
Similarly, relatively bucking voltage V of comparator 36 cOMwhether exceed a default overpower voltage V oPP.As bucking voltage V cOMexceed default overpower voltage V oPP, comparator 36 assert that an overpower event occurs, OPP counter 42 is according to clock signal S tIMER, start counting.In the time that OPP counter 42 finds that overpower event continues to reach the overpower protection time, for example the count results of OPP counter 42 reaches 1000 clock signal S tIMERdefined clock, OPP counter 42 just passes through gate 40, the pulse width modulating signal S that pulse width modulation generator 31 is exported pWMbe fixed as " 0 " in logic, continue to close power switch 14, to reach overpower protection.Similarly, if do not reach the just disappearance of overpower protection time when overpower event continues generation, OPP counter 42 just resets to 0, and stops counting.
In one embodiment, the overcurrent protection time is shorter than the overpower protection time.
Fig. 2 shows in one embodiment of this invention, cycle signal S cYCcycle frequency f cYCand clock signal S tIMERclock frequency f tIMER, to bucking voltage V cOMrelation.In the time of underloading, for instance, bucking voltage V cOMbe less than predeterminated voltage V cOM-L, cycle frequency f cYCbe 0 or a very low 22KHz, can enjoy so lower handoff loss (switching loss), improve the conversion efficiency of power supply unit 10.As bucking voltage V cOMbetween predeterminated voltage V cOM-L-with predeterminated voltage V cOM-Hbetween time, cycle frequency f cYClinear in bucking voltage V cOMchange.As bucking voltage V cOMbetween predeterminated voltage V cOM-Hbe power voltage V oPPtime, mean heavy duty, cycle frequency f cYCfor higher 60KHz.For instance, if the overpower amount of power supply unit 10 is 15 watts, that represents bucking voltage V cOMat overpower voltage V oPPwhen neighbouring, the power output of power supply unit 10 should be approximately 15 watts.Bucking voltage V cOMexceed overpower voltage V oPPtime, cycle frequency f cYCbe elevated to fast 100KHz, with higher cycle frequency, provide in short time peak power, it even reaches the power output of overpower amount twice higher than overpower amount.
In one embodiment, bucking voltage V cOMwhen height exceedes certain value, just starting oscillation of oscillator 37, provides clock signal S tIMER, and its clock frequency f tIMERbe approximately certain value, not with bucking voltage V cOMand change.Fig. 2 read clock frequency f tIMERat bucking voltage V cOMhigher than predeterminated voltage V cOM-H-in time, just occurs, and its clock frequency f tIMERapproximately be fixed as 22KHz.At bucking voltage V cOMbe less than predeterminated voltage V cOM-Hin carry or when underloading, oscillator 37 nonoscillatory, can reduce the internal loss of power-supply controller of electric 20, increase conversion efficiency.
Power supply take power supply unit 10 as printer is example, in the time that printer operated (not printing) at general year, and bucking voltage V cOMcan design at overpower voltage V oPPbelow.Super-heavy load mode of operation once printer in printing, bucking voltage V cOMto exceed overpower voltage V oPP, comparator 36 assert that overpower event occurs, OPP counter 42 starts counting.Once super-heavy load mode of operation has continued too of a specified duration (exceeding the overpower protection time), will assert that printer operation is wrong, overpower protection is triggered, and power supply unit 10 stops electromotive power output.If bucking voltage V cOMbefore OPP counter 42 does not also arrive the overpower protection time, be just returned to lower than overpower voltage V oPP, that means that printer is in the reasonable scope in the time of super-heavy load operation, and OPP counter 42 will be made zero, and overpower protection can not be triggered.
In one embodiment, oscillator 37 is independent of to oscillator 22 and can obtains more accurate overpower protection time and overcurrent protection time.As shown in Figure 2, for the consideration of conversion efficiency, the cycle frequency f that oscillator 22 produces cYC, its value can be along with bucking voltage V cOMand change.But this measure but can cause the puzzlement in timing.For instance, 100 cycle signal S cYCthe physical length of cycle period, will be along with bucking voltage V cOMtrail change, and have different results.Therefore, independently oscillator 37, the clock signal S producing tIMERnearly fixing clock frequency f tIMER, be used for calculating the time span of overpower event and the generation of overcurrent event, will be relatively accurately with stable, no longer along with bucking voltage V cOMtrack and changing.So overvoltage protection time and overcurrent protection time will be more accurate.
Fig. 3 A shows in one embodiment, is used in the side-play amount V of overcurrent protection oFFSET, with input power V iNthe relation of voltage.As input power V iNwhen higher, side-play amount V oFFSEThigher.In other words, at current detection signal V cSwhen rising, higher input power V iNcan cause comparator 34 in Fig. 1 relatively early to assert the generation of overcurrent event.So, can provide suitable line voltage compensation (linecompensation).Good line voltage compensation, can make overcurrent protection trigger time, out-put supply V oUTon output loading 15 be one roughly not with input power V iNthe certain value changing.In different embodiment, input power V iNdetection can have diverse ways.For instance, power-supply controller of electric 20 can detect in the time of power switch 14 conducting, and inductance coupling high, in the cross-pressure of an auxiliary winding (auxiliarywinding) of transformer 12, reaches and detects input power V iNobject.There is a bleeder circuit to be coupled to input power V at another embodiment iNand between earth connection, bleeder circuit provides ratio in input power V iNvoltage division signal, affect side-play amount V oFFSET.In another embodiment, side-play amount V oFFSETalong with the crest voltage of electric main raises and increases, also can reach suitable line voltage compensation.
Good line voltage compensation, also can adopt side-play amount V oFFSETalong with pulse width modulating signal S pWMopening time (ON time) T oNincrease and diminish to reach, shown in Fig. 3 B.Opening time T oNpulse width modulating signal S pWMbe positioned at the time of logical one, namely power switch 14 maintains the time of conducting.Power supply unit 10 has under identical power output, shorter opening time T oN, meaned input power V iNhigher.Therefore, the side-play amount V in Fig. 3 B oFFSETwith opening time T oNrelation, the line voltage compensation causing, the line voltage compensation that may cause with Fig. 3 A, approaching very.
Embodiments of the invention can obtain more accurate overpower protection time and overcurrent protection time.In addition, embodiments of the invention also provide side-play amount V oFFSETwith input power V iNor side-play amount V oFFSETwith opening time T oNrelation, can reach good line voltage compensation.
The foregoing is only preferred embodiment of the present invention, all equalizations of doing according to the claims in the present invention scope change and modify, and all should belong to covering scope of the present invention.

Claims (11)

1. a power-supply controller of electric, has overpower protection, and it provides a pulse width modulating signal, in order to control a power switch, includes:
One pulse width modulating signal generator, in order to produce this pulse width modulating signal;
One first oscillator, is coupled to this pulse width modulating signal generator, determines a switch periods of this pulse width modulating signal;
One second oscillator, in order to determine the overpower protection time; And
Whether one overpower detector, occur in order to detect an overpower event;
Wherein, in the time that this overpower event continues to reach this overpower protection time, this pulse width modulating signal continues to close this power switch.
2. power-supply controller of electric according to claim 1, wherein, this first oscillator is controlled by a bucking voltage, and it is associated with a power output of a power supply unit.
3. power-supply controller of electric according to claim 2, wherein, this overpower detector is this bucking voltage and a default overpower voltage relatively.
4. power-supply controller of electric according to claim 2, wherein, in the time that this bucking voltage exceedes a preset value, the second oscillator is starting oscillation.
5. power-supply controller of electric according to claim 1, also includes:
One counter, is coupled to this second oscillator, whether continues to reach this overpower protection time in order to calculate this overpower event.
6. power-supply controller of electric according to claim 1, also includes:
Whether one over-current detector, occur in order to detect an overcurrent event;
Wherein, this second oscillator is also in order to determine the overcurrent protection time, and in the time that this overcurrent event continues to reach this overcurrent protection time, this pulse width modulating signal continues to close this power switch.
7. power-supply controller of electric according to claim 6, wherein, this over-current detector is a current detection signal and a current limiting signal relatively, this current detection signal approximately represent to flow through electric current of an inductance element.
8. power-supply controller of electric according to claim 7, wherein, when current detection signal and a side-play amount and while being greater than this current limiting signal, this over-current detector assert that this overcurrent event occurs.
9. power-supply controller of electric according to claim 8, wherein, this side-play amount is associated with the input power at an input of this inductance element.
10. power-supply controller of electric according to claim 8, wherein, this side-play amount is associated with the opening time at this pulse width modulating signal.
11. power-supply controller of electric according to claim 6, also include:
One overpower counter and an overcurrent counter, be all coupled to this second oscillator, whether continues to reach this overpower protection time respectively in order to calculate this overpower event, whether continues to reach this overcurrent protection time with this overcurrent event;
Wherein, this overcurrent protection time is shorter than this overpower protection time.
CN201210514639.2A 2012-12-04 2012-12-04 There is the power-supply controller of electric of overpower protection Active CN103856053B (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI508406B (en) * 2014-08-07 2015-11-11 Power Forest Technology Corp Power conversion apparatus and over power protection method thereof
CN105471284A (en) * 2014-10-06 2016-04-06 力林科技股份有限公司 Power conversion apparatus and over power protection method thereof
CN105870874A (en) * 2016-04-28 2016-08-17 上海斐讯数据通信技术有限公司 Over-current protection circuit
CN109839525A (en) * 2019-03-13 2019-06-04 深圳市鼎阳科技有限公司 A kind of overpower protection method and protective device for electronic load

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20010043479A1 (en) * 2000-03-27 2001-11-22 Tamiji Nagai Power supply apparatus
TWM275624U (en) * 2005-04-11 2005-09-11 System General Corp An over-power protection apparatus
CN102237811A (en) * 2010-04-22 2011-11-09 通嘉科技股份有限公司 Controller and control method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20010043479A1 (en) * 2000-03-27 2001-11-22 Tamiji Nagai Power supply apparatus
TWM275624U (en) * 2005-04-11 2005-09-11 System General Corp An over-power protection apparatus
CN102237811A (en) * 2010-04-22 2011-11-09 通嘉科技股份有限公司 Controller and control method thereof

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI508406B (en) * 2014-08-07 2015-11-11 Power Forest Technology Corp Power conversion apparatus and over power protection method thereof
CN105337513A (en) * 2014-08-07 2016-02-17 力林科技股份有限公司 Power conversion apparatus and over power protection method thereof
CN105337513B (en) * 2014-08-07 2017-12-15 力林科技股份有限公司 Power supply change-over device and its overpower protection method
CN105471284A (en) * 2014-10-06 2016-04-06 力林科技股份有限公司 Power conversion apparatus and over power protection method thereof
CN105471284B (en) * 2014-10-06 2018-03-20 力林科技股份有限公司 Power supply change-over device and its overpower protection method
CN105870874A (en) * 2016-04-28 2016-08-17 上海斐讯数据通信技术有限公司 Over-current protection circuit
CN105870874B (en) * 2016-04-28 2019-11-29 上海斐讯数据通信技术有限公司 A kind of current foldback circuit
CN109839525A (en) * 2019-03-13 2019-06-04 深圳市鼎阳科技有限公司 A kind of overpower protection method and protective device for electronic load
CN109839525B (en) * 2019-03-13 2021-02-02 深圳市鼎阳科技股份有限公司 Over-power protection method and protection device for electronic load

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