CN104253535A - Power supply without high-voltage electrolysis electrolytic capacitor - Google Patents
Power supply without high-voltage electrolysis electrolytic capacitor Download PDFInfo
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- CN104253535A CN104253535A CN201310255165.9A CN201310255165A CN104253535A CN 104253535 A CN104253535 A CN 104253535A CN 201310255165 A CN201310255165 A CN 201310255165A CN 104253535 A CN104253535 A CN 104253535A
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Abstract
The invention discloses a power supply which comprises a bridge rectifier, a ceramic or film capacitor, a DC/DC converter and an alternating current detection circuit. The ceramic or film capacitor is adopted by the power supply to replace a conventional common high-voltage electrolytic capacitor on a power input side, so that firing burning is not caused; the cost is lower; and in addition, the power supply can detect two-end voltage of the ceramic or film capacitor, controls the DC/DC converter to stop conversion when the energy of the ceramic or film capacitor is too low, and detects input end voltage of an output rectification filter circuit in the DC/DC converter by the alternating current detection circuit to output a detection signal to inform an electronic device to synergistically receive supply of output voltage output by the output rectification filter circuit. Therefore, light and heavy load changes of the electronic device employing the power supply can be handled.
Description
Technical field
The invention relates to a kind of power supply unit, and relate to especially a kind of receive AC power and convert thereof into VD with power supply to the power supply unit of electronic installation, wherein, electronic installation is such as liquid crystal display.
Background technology
Fig. 1 is a kind of circuit block diagram of power supply unit of existing liquid crystal display.Refer to Fig. 1, existing power supply unit 1 comprises electromagnetic interference (electromagnetic interference, EMI) filter 11, bridge rectifier 12, electrolytic capacitor 13 and dc-dc (direct-current to direct-current, DC/DC) transducer, wherein, the DC/DC transducer feedback control circuit that comprises commutation circuit 14, transformer 15, first output rectifier and filter 161, second output rectifier and filter 162 and be made up of feedback circuit 17 and control circuit 18.AC power after electromagnetic interface filter 11 filtering Conducted EMI noise, then through bridge rectifier 12 rectification and be filtered into galvanic current by electrolytic capacitor 13 and press Vdc.This direct voltage Vdc is after commutation circuit 14 cuts into high-frequency square-wave signal, again through the transformer 15 prior voltage quasi position set of level side winding acquisition secondarily, and then through the first output rectifier and filter 161 rectification be filtered into the first output voltage Vo1, and through the second output rectifier and filter 162 rectification be filtered into the second output voltage Vo2, wherein, first output voltage Vo1(is specified is such as 5V) power to the mainboard 31 of liquid crystal display 3, and the second output voltage Vo2(specified be such as 10 ~ 50V) power supply to the backlight module 32 of liquid crystal display 3.Feedback circuit 17 detects the first output voltage Vo1 with output feedback signal to control circuit 18, makes control circuit 18 control the handoff parameter of commutation circuit 14, as duty ratio (duty cycle), obtains the first and second stable output voltage Vo1 and Vo2.
Because existing power supply unit 1 adopts electrolytic capacitor 13 at input side, the full-wave rectified voltage that bridge rectifier 12 rectifier obtains is filtered into direct voltage Vdc, therefore electrolytic capacitor 13 in normal operation its both end voltage Vdc be namely the peak value of AC power input voltage.For 120Vrms AC mains source, Taiwan, the both end voltage Vdc of electrolytic capacitor 13 is about 170V, such high pressure can increase the electrostatic energy that electrolytic capacitor 13 electrode gathers, and accumulate in electrostatic energy in electrolytic capacitor 13 under certain conditions (such as AC power input voltage is abnormal to be raised) directly can carry out sparkover by arcing between electrode, and then the electrolyte caused in electrolytic capacitor 13 and isolate the combustible combustion such as lining paper.In addition, electrolytic capacitor 13 may because of itself design or quality bad, make electrolyte can from capacitor to external leakage or gush and track to the circuit region having high pressure, cause short circuit, arcing, cause electrolyte on fire and and then the combustible catching fire caused beyond electrolyte.
Summary of the invention
Object of the present invention proposition a kind of power supply unit without high-voltage electrolysis capacitor, it does not adopt electrolytic capacitor at input side, therefore in circuit without high-voltage electrolysis capacitor, the catching fire problem that electrolytic capacitor may cause can be avoided.
For achieving the above object or other object, the present invention proposes a kind of power supply unit without high-voltage electrolysis capacitor, is applicable to electronic installation.Power supply unit comprises bridge rectifier, pottery or film capacitor, dc-dc (DC/DC) transducer and exchanges circuit for detecting.The input of bridge rectifier couples AC power.The two ends of pottery or film capacitor couple the output of bridge rectifier.DC/DC transducer comprises commutation circuit, transformer, the first output rectifier and filter and the second output rectifier and filter and feedback control circuit.Commutation circuit couples the primary side winding of pottery or film capacitor and transformer.The primary side winding of transformer couples the input of the first output rectifier and filter and the second output rectifier and filter.The output of the first output rectifier and filter and the second output rectifier and filter exports the first output voltage respectively and the second output voltage is powered to electronic installation, and wherein, the first output voltage is powered to the main control circuit of electronic installation.Feedback control circuit is coupled between the output of the first output rectifier and filter and the control end of commutation circuit or is coupled between another primary side winding of transformer and the control end of commutation circuit, feedback control circuit by the both end voltage of more ceramic or film capacitor and minimum operating voltage set point whether to control commutation circuit work.The input exchanging circuit for detecting couples the input of the first output rectifier and filter, the output exchanging circuit for detecting exports detection signal, and detection signal is the first level when both end voltage that is ceramic or film capacitor is greater than minimum operating voltage set point, and be the second level when both end voltage that is ceramic or film capacitor is less than minimum operating voltage set point.
The main control circuit of electronic installation is when receiving the external command of unlatching, start to detect the detection signal exchanging circuit for detecting and export, and other circuit controlling electronic installation after detecting the rising edge through giving tacit consent to several detection signal starts the power supply receiving the first output voltage and the second output voltage.In addition, the main control circuit of electronic installation is when receiving the external command of closedown, and other circuit controlling electronic installation stops the power supply of reception first output voltage and the second output voltage.
In one embodiment, DC/DC transducer can be flyback converter (flyback converter).One end of commutation circuit couples one end of the primary side winding of transformer, and the other end of the primary side winding of transformer couples one end of pottery or film capacitor, and the other end of pottery or film capacitor couples the other end of commutation circuit.First output rectifier and filter and the second output rectifier and filter can all comprise diode and capacitor, wherein, one end of the cathode terminal coupling capacitor of diode, the anode tap of diode and the other end of capacitor couple the primary side winding two ends of transformer respectively, and the both end voltage of capacitor is the first or second output voltage.Commutation circuit can comprise field-effect transistor, and the drain electrode end of field-effect transistor, source terminal and gate terminal couple two ends and the control end of commutation circuit respectively.
In one embodiment, electronic installation can be liquid crystal display.First output voltage is powered to the mainboard of liquid crystal display, and main control circuit is arranged on mainboard.Second output voltage is powered to the backlight module of liquid crystal display.
In one embodiment, feedback control circuit can comprise pulse-width modulation (pulse-width modulation, PWM) controller, and PWM controller can comprise bleeder circuit and comparator.Bleeder circuit coupled in parallel in pottery or film capacitor two ends between, bleeder circuit exports a voltage.Comparator compares voltage and reference voltage that bleeder circuit exports whether to control commutation circuit work, and wherein, the voltage that bleeder circuit exports equals the ratio of reference voltage and minimum operating voltage set point with the ratio of the both end voltage of ceramic or film capacitor.
In one embodiment, exchange circuit for detecting and can comprise diode, resistor, capacitor and comparator.The anode tap of diode couples the input of the first output rectifier and filter, the first end of the cathode terminal coupling resistance device of diode, the first end of capacitor and the positive input terminal of comparator.Second end of resistor and the second end ground connection of capacitor.The negative input end of comparator receives reference voltage, and the output of comparator exports detection signal.Exchange circuit for detecting and more can comprise bleeder circuit, bleeder circuit coupled in parallel is between the output of the first output rectifier and filter, and bleeder circuit output reference voltage is to the negative input end of comparator.
The present invention instead of the existing high-voltage electrolysis capacitor being commonly used in mains input side because adopting pottery or film capacitor, do not contain electrolyte because of pottery or film capacitor and can be designed to not containing isolation lining paper, so likely can not cause the problem of catching fire as high-voltage electrolysis capacitor, and the cost of pottery or film capacitor is also lower than high-voltage electrolysis capacitor.In addition, the present invention also detects the both end voltage of pottery or film capacitor by control circuit, control commutation circuit when energy on pottery or film capacitor is too little and quit work the conversion work stopping DC/DC transducer, and detect the input terminal voltage of the first output rectifier and filter to export the power supply that detection signal notice electronic installation receives the first output voltage and the second output voltage ordinatedly by exchanging circuit for detecting, the weight therefore being dealt with electronic installation carries change.
For above and other object of the present invention, feature and advantage can be become apparent, preferred embodiment cited below particularly, and coordinate institute's accompanying drawings, be described in detail below.
Accompanying drawing explanation
Fig. 1 is a kind of circuit block diagram of power supply unit of existing liquid crystal display.
Fig. 2 is the circuit block diagram of the power supply unit according to one embodiment of the invention.
The electronic installation that Fig. 3 is power supply unit shown in Fig. 2 and power supply thereof coordinates the sequential chart of running.
Fig. 4 is the circuit block diagram of the power supply unit according to another embodiment of the present invention.
Fig. 5 is the circuit diagram of the power supply unit according to one embodiment of the invention.
Fig. 6 is the circuit diagram of another embodiment of PWM controller shown in Fig. 5.
Symbol description
1,2,2 ': power supply unit
11:EMI filter
12: bridge rectifier
13: electrolytic capacitor
14: commutation circuit
15: transformer
Na: auxiliary winding
Np, Np ': primary side winding
Ns1, Ns2: primary side winding
161: the first output rectifier and filters
162: the second output rectifier and filters
17,17 ': feedback circuit
18: control circuit
23: pottery or film capacitor
28: control circuit
29: exchange circuit for detecting
3: liquid crystal display
31: mainboard
311: main control circuit
32: backlight module
AND1, AND2, AND3: with door
C1, C2, C3, C4, C5: capacitor
CMP1, CMP2, CMP3, CMP4, CMP5: comparator
D1, D2, D3, D4: diode
FF1:RS trigger
I1: current source
OR1: or door
Q1: field-effect transistor
R1, R2, R3, R4, R5, R6, R7: resistor
U1, U2:PWM controller
COMP, CS, CT, GND, HV, OUT, RQ, VCC: pin position
Vdc: direct voltage
Vo1: the first output voltage
Vo2: the second output voltage
Vp: the both end voltage of pottery or film capacitor
Vmin: minimum operating voltage set point
Vr1, Vr2, Vr3, Vr4: reference voltage
DET: detection signal
Re1, re2, re1 ', re2 ': the rising edge of detection signal
T: time.
Embodiment
In the following description, be keep consistency that the present invention is illustrated, therefore in various embodiments, if there is the same or analogous assembly of function and structure can by identical element numbers and title.Another is know to present feature of the present invention, omits the known assembly of part in institute's accompanying drawings.
Fig. 2 is the circuit block diagram of the power supply unit according to one embodiment of the invention, and the electronic installation that Fig. 3 is power supply unit shown in Fig. 2 and power supply thereof coordinates the sequential chart of running.Please first see Fig. 2, power supply unit 2 of the present invention is for power supply to electronic installation, and in the present embodiment, electronic installation is liquid crystal display 3.Power supply unit 2 of the present invention comprises electromagnetic interface filter 11, bridge rectifier 12, pottery or film capacitor 23, DC/DC transducer and exchanges circuit for detecting 29, wherein, the DC/DC transducer feedback control circuit that comprises commutation circuit 14, transformer 15, first output rectifier and filter 161, second output rectifier and filter 162 and be made up of feedback circuit 17 and control circuit 28.Compared with power supply unit 1 existing shown in Fig. 1, power supply unit 2 of the present invention adopts pottery or film capacitor 23 to instead of as shown in Figure 1 at the high-voltage electrolysis capacitor 13 of mains input side, do not contain electrolyte because of pottery or film capacitor 23 and can be designed to not containing isolation lining paper, so likely can not cause the problem of catching fire as electrolytic capacitor 13.
But, because the capacitance of pottery or film capacitor 23 is less, filter effect is poor, the both end voltage Vp of pottery or film capacitor 23 is made to be a pulsating dc voltage as shown in Figure 3, instead of a galvanic current pressure, the weight causing power supply unit 2 of the present invention cannot deal with liquid crystal display 3 well carries change.In order to overcome this problem, power supply unit 2 of the present invention also detects the both end voltage Vp of pottery or film capacitor 23 by control circuit 28, detect when voltage Vp is less than minimum operating voltage set point control commutation circuit 14 quit work, DC/DC transducer is made to stop conversion work, this is because now pottery or film capacitor 23 on energy too little, make the conversion efficiency of DC/DC transducer become very poor, therefore allow DC/DC transducer stop conversion work.As shown in Figure 3, this section is called dead band allow DC/DC transducer stop conversion work because of voltage Vp is less than minimum operating voltage set point Vmin during.When dead band, by by capacitor (C1 and C2 as shown in Figure 5 in the first and second output rectifier and filters 161 and 162, can describe in detail more below) stored by energy continue power supply to liquid crystal display 3, therefore power supply needed for liquid crystal display 3 time in order to store that more multi-energy is to deal with dead band, therefore in design usually can at the extra capacitor (not illustrating) of the output coupled in parallel of the first and second output rectifier and filters 161 and 162, or directly use the capacitor in the first and second output rectifier and filters 161 and 162 instead capacitance larger capacitor.In addition, power supply unit 2 of the present invention also detects the input terminal voltage of the first output rectifier and filter 161 by exchanging circuit for detecting 29, to export with the detection signal DET of dead band information to liquid crystal display 3, make liquid crystal display 3 can avoid dead band to start receiving according to detection signal DET the power supply of the first and second output voltage Vo1 and Vo2 when receiving the external command of unlatching, namely avoid dead band to start eating and carry (especially arduous year), therefore power supply unit 2 of the present invention is that the weight coordinating running to deal with liquid crystal display 3 by notice liquid crystal display 3 carries change.
Specifically, in power supply unit 2 of the present invention, the input of bridge rectifier 12 couples outside AC power by electromagnetic interface filter 11.The two ends of pottery or film capacitor 23 couple the output of bridge rectifier 12.Commutation circuit 14 couples the primary side winding of pottery or film capacitor 23 and transformer 15.The primary side winding of transformer 15 couples the input of the first and second output rectifier and filters 161 and 162.The output of the first and second output rectifier and filters 161 and 162 exports the first and second output voltage Vo1 and Vo2 respectively and powers to liquid crystal display 3, wherein, first output voltage Vo1 powers to the mainboard 31 of liquid crystal display 3, comprise power supply to the main control circuit 311 be arranged on mainboard 31, and the second output voltage Vo2 powers to the backlight module 32 of liquid crystal display 3.Feedback control circuit (be made up of feedback circuit 17 and control circuit 28) is coupled between the output of the first output rectifier and filter 161 and the control end of commutation circuit 14.Feedback circuit 17 detects the first output voltage Vo1 with output feedback signal to control circuit 28, makes control circuit 28 control the handoff parameter of commutation circuit 14, as duty ratio, obtains the first and second stable output voltage Vo1 and Vo2.The both end voltage Vp of pottery or film capacitor 23 also detected by control circuit 28, and whether worked to control commutation circuit 14 by comparative voltage Vp and minimum operating voltage set point Vmin, when voltage Vp is less than minimum operating voltage set point Vmin, (during in dead band) controls commutation circuit 14 and quits work, and makes DC/DC transducer stop conversion work.Exchange the input of circuit for detecting 29 and couple the input of the first output rectifier and filter 161 to detect its input terminal voltage, then export detection signal DET with dead band information to liquid crystal display 3 from the output exchanging circuit for detecting 29.As shown in Figure 3, detection signal DET is the first level (be the high levle of 5V at the present embodiment) when voltage Vp is greater than minimum operating voltage set point Vmin, and is the second level (be the low level of 0V at the present embodiment) when voltage Vp is less than minimum operating voltage set point Vmin.
Please simultaneously see Fig. 2 and Fig. 3, after AC power input, power supply unit 2 starts to export the first and second output voltage Vo1 and Vo2, therefore the first and second output voltage Vo1 and Vo2 can climb by zero.When the first output voltage Vo1 climbs minimum (be 4.2V at the present embodiment) of main control circuit 311, main control circuit 311 is started working and is controlled liquid crystal display and is in holding state, namely the power supply that liquid crystal display 3 other circuit except main control circuit 311 does not all receive the first and second output voltage Vo1 and Vo2 is controlled, even main control circuit 311 is also closed most function and is only retained the function whether monitoring have external command to input, therefore liquid crystal display 3 eats underloading.
When main control circuit 311 receives the external command of unlatching, main control circuit 311 starts to detect the detection signal DET exchanging circuit for detecting 29 and export, and after detecting the rising edge through giving tacit consent to several detection signal (be 2 rising edge re1 and re2 at the present embodiment), control other circuit of liquid crystal display 3, as the circuit on mainboard 31 except main control circuit 311 and backlight module 32, start the power supply receiving the first and second output voltage Vo1 and Vo2, therefore liquid crystal display 3 starts arduous carrying and normally works.In the present embodiment, start arduous carrying just controlling liquid crystal display 3 after rising edge re1 and re2 of 2 detection signals, be carry to just start to allow liquid crystal display 3 eat after making the first and second output voltage Vo1 and Vo2 comparatively stable, and after rising edge re2, allow liquid crystal display 3 eat carry and can avoid dead band at once.In addition, because when dead band, DC/DC transducer will stop conversion work and energy stored by the capacitor (C1 and C2 as shown in Figure 5) in the first and second output rectifier and filters 161 and 162 continues power supply to liquid crystal display 3, thus one enter dead band after the first and second output voltage Vo1 and Vo2 can start to decline.Power supply needed for liquid crystal display 3 when being unable to cope with dead band to not allow the first and second output voltage Vo1 and Vo2 drop to, in design usually can at the extra capacitor of the output coupled in parallel of the first and second output rectifier and filters 161 and 162, or directly use the capacitor in the first and second output rectifier and filters 161 and 162 instead capacitance larger capacitor, power supply needed for liquid crystal display 3 when more multi-energy deals with dead band can be stored, such as design the first output voltage Vo1 can not drop to 5V rated voltage 90%(and 4.5V when dead band) below.
When liquid crystal display 3 normally works, when main control circuit 311 receives the external command of closedown, main control circuit 311 controls the power supply that liquid crystal display 3 other circuit except main control circuit 311 stops reception first and second output voltage Vo1 and Vo2, even main control circuit 311 is also closed most function and is only retained the function whether monitoring have external command to input, therefore liquid crystal display 3 is eaten underloading and entered holding state.The external command of unlatching is again received once main control circuit 311, main control circuit 311 detects starting again the detection signal DET exchanging circuit for detecting 29 and export, and after detecting the rising edge through giving tacit consent to several detection signal (be 2 rising edge re1s ' and re2 ' at the present embodiment), other circuit controlling liquid crystal display 3 starts the power supply receiving the first and second output voltage Vo1 and Vo2, therefore liquid crystal display 3 will start again arduous carrying and normally work.
Fig. 4 is the circuit block diagram of the power supply unit according to another embodiment of the present invention.Please simultaneously see Fig. 2 and Fig. 4, power supply unit 2 shown in Fig. 2 adopts secondary side feedback controling mode, therefore feedback control circuit (be made up of feedback circuit 17 and control circuit 28) is coupled between the output of the first output rectifier and filter 161 and the control end of commutation circuit 14, the first output voltage Vo1 that feedback circuit 17 detecting is wherein positioned at secondary side to control circuit 28, makes control circuit 28 control the handoff parameter of commutation circuit 14 with output feedback signal.Power supply unit 2 ' shown in Fig. 4 adopts primary side feedback controling mode, therefore feedback control circuit (be made up of feedback circuit 17 ' and control circuit 28) is coupled between another primary side winding Np ' of transformer 15 and the control end of commutation circuit 14, the primary side current that feedback circuit 17 ' is wherein positioned at the transformer 15 of primary side by primary side winding Np ' detecting to control circuit 28, makes control circuit 28 control the handoff parameter of commutation circuit 14 with output feedback signal.
Fig. 5 is the circuit diagram of the power supply unit according to one embodiment of the invention.For power supply unit 2 shown in Fig. 2, please simultaneously see Fig. 2 and Fig. 5, in the present embodiment, DC/DC transducer is flyback converter, and commutation circuit 14 adopts field-effect transistor Q1, the drain electrode end of field-effect transistor Q1, source terminal and gate terminal couple two ends and the control end of commutation circuit 14 respectively.One end (i.e. the drain electrode end of field-effect transistor Q1) of commutation circuit 14 couples one end of the primary side winding Np of transformer 15, the other end of the primary side winding Np of transformer 15 couples one end of pottery or film capacitor 23, the other end ground connection of pottery or film capacitor 23, and the other end of commutation circuit 14 (i.e. the source terminal of field-effect transistor Q1) is also by resistor R1 ground connection, therefore can say that the other end of pottery or film capacitor 23 couples the other end (i.e. the source terminal of field-effect transistor Q1) of commutation circuit 14.
In the present embodiment, first output rectifier and filter 161 comprises diode D1 and capacitor C1, wherein, one end of the cathode terminal coupling capacitor C1 of diode D1, the anode tap of diode D1 and the other end of capacitor C1 couple the primary side winding Ns1 two ends of transformer 15 respectively, and the both end voltage of capacitor C1 is the first output voltage Vo1.Second output rectifier and filter 162 comprises diode D2 and capacitor C2, wherein, one end of the cathode terminal coupling capacitor C2 of diode D2, the anode tap of diode D2 and the other end of capacitor C2 couple the primary side winding Ns2 two ends of transformer 15 respectively, and the both end voltage of capacitor C2 is the second output voltage Vo2.
In the present embodiment, control circuit 28 comprises PWM controller U1, resistor R1 and R2, diode D3 and capacitor C3 and C4.PWM controller U1 be such as modify to meet for the universal PWM controller integrated circuit (integrated circuit, IC) of LD7576 required for the present invention.The PWM controller IC of LD7576 has seven pin positions CT, COMP, CS, GND, OUT, VCC and HV.Its internal circuit framework is outline at this, IC startup stage, current source I1 draws electric current by resistor R2 from pottery or film capacitor 23 from pin position HV, charge to capacitor C3 through pin position VCC to provide starting current, and be charged to comparator CMP1 when its both end voltage is greater than reference voltage Vr1 at capacitor C3 and output signal turn off current source I1, then IC starts working and the power supply circuits be made up of auxiliary winding Na, diode D3 and the capacitor C3 of transformer 15 are powered.
Normal conversation after IC starts, IC is from the switching of pin position OUT output pwm signal controlling filed effect transistor Q1, DC/DC transducer is made to carry out conversion work, and capture the both end voltage (it comprises the primary side current information of transformer 15) of the resistor R1 of coupled in series between the source terminal of field-effect transistor Q1 and ground from pin position CS and come to compare with reference voltage Vr2 by comparator CMP2, to provide overcurrent protection, also obtain the feedback signal that sends of feedback circuit 17 from pin position COMP in addition and come to compare with the resistor R1 both end voltage comprising primary side current information by comparator CMP3, to produce pwm signal.In addition; IC also by by or door OR1, rest-set flip-flop (Flip Flop) FF1 with door logical circuit that AND1 forms; receive other control signal as overload protection, overvoltage protection, energy saver mode control etc., limit pwm signal that comparator CMP3 produces so that the control signal of the overcurrent protection exported with comparator CMP2 is combined and determines whether it exports from pin position OUT.
PWM controller U1 of the present invention adds the bleeder circuit and comparator CMP4 that are made up of resistor R3 and R4 in the PWM controller IC of LD7576, by script IC with the newly-increased input of door and become with door AND1(that it has 7 inputs) to couple the output of comparator CMP4.One end of bleeder circuit (be made up of resistor R3 and R4) couples one end of pottery or film capacitor 23 by resistor R2 from pin position HV, and the equal ground connection of the other end of the other end of bleeder circuit and pottery or film capacitor 23, therefore bleeder circuit coupled in parallel is between the two ends of pottery or film capacitor 23, and bleeder circuit exports a voltage.Comparator CMP4 compare voltage that bleeder circuit (be made up of resistor R3 and R4) exports and reference voltage Vr3 with export control control signal that whether commutation circuit 14 work to door AND1.Wherein, the ratio of the both end voltage of the voltage that bleeder circuit (be made up of resistor R3 and R4) exports and pottery or film capacitor 23 equals the ratio of reference voltage Vr3 and minimum operating voltage set point Vmin, therefore, IC designer decides the size of minimum operating voltage set point Vmin by the resistance value of design resistor R3 and R4 and the size of reference voltage Vr3, namely determines the length in dead band.
In the present embodiment, the bleeder circuit that circuit for detecting 29 comprises diode D4, resistor R5, capacitor C5, comparator CMP5 and is made up of resistor R6 and R7 is exchanged.The anode tap of diode D4 couples the input of the first output rectifier and filter 161, the first end of the cathode terminal coupling resistance device R5 of diode D4, the first end of capacitor C5 and the positive input terminal of comparator CMP5.Second end of resistor R5 and the second end ground connection of capacitor C5.Bleeder circuit (be made up of resistor R6 and R7) coupled in parallel between the output of the first output rectifier and filter 161, the negative input end of bleeder circuit output reference voltage Vr4 to comparator CMP5.Comparator CMP5 compares its positive-negative input end voltage and exports detection signal DET from its output according to this.By the resistance value of design resistor R5 and the capacitance of capacitor C5, namely its product is the time constant relevant with capacitor C5 charge/discharge rates, the fall time of the falling edge of detection signal DET can be determined, therefore namely can affect the detecting sensitivity exchanging circuit for detecting 29.
Fig. 6 is the circuit diagram of another embodiment of PWM controller U1 shown in Fig. 5.Refer to Fig. 6, compared with PWM controller U1 shown in Fig. 5, PWM controller U2 do not revise in the PWM controller IC of originally LD7576 it has 6 inputs with door AND2(), but or door OR1 and rest-set flip-flop FF1 between more newly-increased one with door AND3, couple respectively with two inputs of door AND3 or the output of door OR1 and the output of comparator CMP4, then couple the input of rest-set flip-flop FF1 with the output of door AND3.In addition, PWM controller U2 is a newly-increased pin position RQ also, resistor R4 in bleeder circuit is designed at IC outside, thus, the size of user when using this IC by adopting the resistor R4 of different resistance values to decide minimum operating voltage set point Vmin, namely determines the length in dead band.
Although the present invention discloses as above with preferred embodiment; so itself and be not used to limit the present invention, anyly have the knack of this those skilled in the art, without departing from the spirit and scope of the present invention; when doing a little change and retouching, therefore protection scope of the present invention is when being as the criterion depending on the claim person of defining.
Claims (9)
1. without the power supply unit of high-voltage electrolysis capacitor, be applicable to an electronic installation, it is characterized in that, this power supply unit comprises: a bridge rectifier, and its input couples an AC power, one pottery or film capacitor, its two ends couple the output of this bridge rectifier, one DC-DC converter, comprise a commutation circuit, one transformer, one first output rectifier and filter, one second output rectifier and filter, and a feedback control circuit, this commutation circuit couples the primary side winding of this pottery or film capacitor and this transformer, the primary side winding of this transformer couples the input of this first output rectifier and filter and the input of this second output rectifier and filter, the output of this first output rectifier and filter and the output of this second output rectifier and filter export one first output voltage respectively and one second output voltage is powered to this electronic installation, this first output voltage is powered to a main control circuit of this electronic installation, this feedback control circuit is coupled between the output of this first output rectifier and filter and the control end of this commutation circuit, or be coupled between another primary side winding of this transformer and the control end of this commutation circuit, this feedback control circuit by the minimum operating voltage set point of both end voltage and that compares this pottery or film capacitor whether to control this commutation circuit work, and one exchanges circuit for detecting, its input couples the input of this first output rectifier and filter, its output exports a detection signal, this detection signal is one first level when the both end voltage of this pottery or film capacitor is greater than this minimum operating voltage set point, and is one second level when the both end voltage of this pottery or film capacitor is less than this minimum operating voltage set point, wherein, this main control circuit is when receiving the external command of a unlatching, start to detect this detection signal, and other circuit controlling this electronic installation after detecting the rising edge through giving tacit consent to this detection signal several starts the power supply receiving this first output voltage and this second output voltage.
2. power supply unit as claimed in claim 1, wherein, this main control circuit is when receiving the external command of a closedown, and other circuit controlling this electronic installation stops the power supply receiving this first output voltage and this second output voltage.
3. power supply unit as claimed in claim 1, wherein, this DC-DC converter is a flyback converter, one end of this commutation circuit couples one end of the primary side winding of this transformer, the other end of the primary side winding of this transformer couples one end of this pottery or film capacitor, the other end of this pottery or film capacitor couples the other end of this commutation circuit, this first output rectifier and filter and this second output rectifier and filter all comprise a diode and a capacitor, the cathode terminal of this diode couples one end of this capacitor, the other end of the anode tap of this diode and this capacitor couples the primary side winding two ends of this transformer respectively, the both end voltage of this capacitor is this first output voltage or this second output voltage.
4. power supply unit as claimed in claim 3, wherein, this commutation circuit comprises a field-effect transistor, and the drain electrode end of this field-effect transistor, source terminal and gate terminal couple two ends and the control end of this commutation circuit respectively.
5. power supply unit as claimed in claim 1, wherein, this electronic installation is a liquid crystal display.
6. power supply unit as claimed in claim 5, wherein, this first output voltage is powered to a mainboard of this liquid crystal display, and this main control circuit is arranged on this mainboard, and this second output voltage is powered to a backlight module of this liquid crystal display.
7. power supply unit as claimed in claim 1, wherein, this feedback control circuit comprises a PDM keyer, this PDM keyer comprises a bleeder circuit and a comparator, this bleeder circuit coupled in parallel is between the two ends of this pottery or film capacitor, this bleeder circuit exports a voltage, this comparator compares this voltage and a reference voltage whether to control this commutation circuit work, wherein, the ratio of the both end voltage of this voltage and this pottery or film capacitor equals the ratio of this reference voltage and this minimum operating voltage set point.
8. power supply unit as claimed in claim 1, wherein, this interchange circuit for detecting comprises a diode, a resistor, a capacitor and a comparator, the anode tap of this diode couples the input of this first output rectifier and filter, the cathode terminal of this diode couples the positive input terminal of the first end of this resistor, the first end of this capacitor and this comparator, second end of this resistor and the second end ground connection of this capacitor, the negative input end of this comparator receives a reference voltage, and the output of this comparator exports this detection signal.
9. power supply unit as claimed in claim 8, wherein, this interchange circuit for detecting more comprises a bleeder circuit, and this bleeder circuit coupled in parallel is between the output of this first output rectifier and filter, and this bleeder circuit exports this reference voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310255165.9A CN104253535A (en) | 2013-06-25 | 2013-06-25 | Power supply without high-voltage electrolysis electrolytic capacitor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310255165.9A CN104253535A (en) | 2013-06-25 | 2013-06-25 | Power supply without high-voltage electrolysis electrolytic capacitor |
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| Publication Number | Publication Date |
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| CN104253535A true CN104253535A (en) | 2014-12-31 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201310255165.9A Pending CN104253535A (en) | 2013-06-25 | 2013-06-25 | Power supply without high-voltage electrolysis electrolytic capacitor |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105553301A (en) * | 2016-02-25 | 2016-05-04 | 国网青海省电力公司海南供电公司 | Power supply device having wide input adaptability |
| CN105991033A (en) * | 2015-01-21 | 2016-10-05 | 杰力科技股份有限公司 | Power converter without electrolytic capacitor at input side |
| CN106425033A (en) * | 2016-11-30 | 2017-02-22 | 南京顶瑞电机有限公司 | Positioning welding gun power adapter and method based on single chip microcomputer control |
| CN111525805A (en) * | 2019-02-01 | 2020-08-11 | 群光电能科技股份有限公司 | Power converter with over-temperature protection compensation |
-
2013
- 2013-06-25 CN CN201310255165.9A patent/CN104253535A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105991033A (en) * | 2015-01-21 | 2016-10-05 | 杰力科技股份有限公司 | Power converter without electrolytic capacitor at input side |
| CN105991033B (en) * | 2015-01-21 | 2018-08-28 | 杰力科技股份有限公司 | Power converter without electrolytic capacitor at input side |
| CN105553301A (en) * | 2016-02-25 | 2016-05-04 | 国网青海省电力公司海南供电公司 | Power supply device having wide input adaptability |
| CN106425033A (en) * | 2016-11-30 | 2017-02-22 | 南京顶瑞电机有限公司 | Positioning welding gun power adapter and method based on single chip microcomputer control |
| CN111525805A (en) * | 2019-02-01 | 2020-08-11 | 群光电能科技股份有限公司 | Power converter with over-temperature protection compensation |
| US11050341B2 (en) | 2019-02-01 | 2021-06-29 | Chicony Power Technology Co., Ltd. | Power converter with over temperature protection compensation |
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Application publication date: 20141231 |
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