CN204290732U - Switching power supply system and control circuit thereof - Google Patents
Switching power supply system and control circuit thereof Download PDFInfo
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- CN204290732U CN204290732U CN201420836164.3U CN201420836164U CN204290732U CN 204290732 U CN204290732 U CN 204290732U CN 201420836164 U CN201420836164 U CN 201420836164U CN 204290732 U CN204290732 U CN 204290732U
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Abstract
The utility model discloses a switching power supply system and control circuit thereof. Wherein switching power supply system includes: the input end of the rectifying circuit is coupled with an alternating current input voltage, and the output end of the rectifying circuit provides the input voltage of the switching circuit; the switching circuit comprises a power switch, and the output end of the switching circuit is coupled with a load; and the control circuit comprises an integrating circuit, wherein the input end of the integrating circuit is coupled with an output current signal representing the output current, the output end of the integrating circuit provides a charge signal, and the output end of the control circuit is coupled with the control end of the power switch. The switching power supply system and the control circuit thereof can effectively eliminate the flicker phenomenon in the LED and have the advantages of low power consumption, simple circuit, reliable control and the like.
Description
Technical field
The utility model relates to circuit, concrete but be not limited to relate to the switch power supply system for eliminating LED lamp source flicker and control circuit thereof.
Background technology
Triode ac switch (TRIAC) device is widely used in carrying out light modulation to light-emitting diode (LED) illuminator.TRIAC device receives AC power, and carrys out truncation part alternating voltage by the angle of flow of control TRIAC device, thus reaches adjustment input energy thus reach light modulation object.But due to the disturbance of AC power, the angle of flow affecting TRIAC device blocks opportunity, therefore its energy exported is unstable at different ac cycles, very easily causes the flicker of LED.Occur for avoiding this situation, a kind of existing method is after TRIAC device, add that adjustable earial drainage device (Breeder) circuit of resistance is used for stablizing the output of TRIAC device, but this method power consumption penalty is large, and electric energy efficiency is low, too increases the requirement of system radiating simultaneously.Another kind method adopts multilevel voltage converter, as increased voltage up converting circuit before inverse excitation type converter, but such a process increases a lot of elements, considerably increasing volume and manufacturing cost.
In addition, in the occasion that some other does not adopt TRIAC light adjusting circuit or does not adopt light adjusting circuit, there is the requirement to power supply stable output too.
Utility model content
In order to solve the problem of at least one or more above-mentioned proposition, the utility model proposes a kind of switch power supply system and control circuit thereof.
According to an aspect of the present utility model, a kind of control circuit for control switch circuit comprises:
Integrating circuit, has input and output, and wherein input couples the output current signal characterizing switching circuit output current, and output provides charge signal; Charge control circuit, have first input end, the second input and output, wherein the first input end of charge control circuit couples charge signal, and the second input of charge control circuit couples charge reference signal; And ON-OFF control circuit, have input and output, wherein the input of ON-OFF control circuit couples the output of charge control circuit, and the output of ON-OFF control circuit provides switch controlling signal to the control end of the power switch of switching circuit.In one embodiment, charge control circuit comprises: gain control circuit, there is first input end, the second input and output, wherein the first input end of gain control circuit couples charge signal, second input of gain control circuit couples charge reference signal, and the output of gain control circuit provides gain modulation signal; And mlultiplying circuit, there is input, control end and output, wherein the input of mlultiplying circuit couples the input of switching circuit, the control end of mlultiplying circuit couples the output of gain control circuit, the output of mlultiplying circuit couples the input of ON-OFF control circuit, and the output of mlultiplying circuit provides the input voltage signal through gain modulation.In one embodiment, control circuit comprises current feedback circuit further, current feedback circuit couples the input of switching circuit and provides input current signal, and when input current signal is greater than the input voltage signal through gain modulation, power switch is off state.In one embodiment, charge control circuit comprises: charge reference signal circuit for generating, has input and output, and the output of charge reference signal circuit for generating provides charge reference signal; Electric charge comparison circuit, there is first input end, the second input and output, wherein first input end couples the output of integrating circuit, and the second input couples the output of charge reference signal circuit for generating, and the output of electric charge comparison circuit provides electric charge comparison signal; Gain modulation circuit, has input and output, and the input of gain modulation circuit couples the output of electric charge comparison circuit, and the output of gain modulation circuit provides gain modulation signal; Mlultiplying circuit, has input, control end and output, and wherein the input of mlultiplying circuit couples the input of switching circuit, and the control end of mlultiplying circuit couples the output of gain modulation circuit, and the output of mlultiplying circuit provides current reference signal; First latch cicuit, has set input, the RESET input and output, and wherein the set input of the first latch cicuit couples input voltage measurement signal, and the RESET input of the first latch cicuit couples the output of electric charge comparison circuit; And with door, there is first input end, the second input and output, wherein couple the output of ON-OFF control circuit with the first input end of door, couple the output of the first latch cicuit with the second input of door, couple the control end of power switch with the output of door.In one embodiment, ON-OFF control circuit comprises: current comparison circuit, there is first input end, the second input and output, wherein the first input end of current comparison circuit couples the output of mlultiplying circuit, second input of current comparison circuit couples input current signal, and the output of current comparison circuit provides electric current comparison signal; And second latch cicuit, have set input, the RESET input and output, wherein set input couples asserts signal, and the RESET input couples the output of current comparison circuit, and the output of the second latch cicuit couples the first input end with door.In one embodiment, charge reference signal circuit for generating comprises: low pass filter, has input and output, and wherein the input of low pass filter couples the input of switching circuit; And clamp down on circuit, have input and output, the input wherein clamping down on circuit couples the output of low pass filter, and the output clamping down on circuit provides charge reference signal.In one embodiment, control circuit comprises signaling conversion circuit further, the input of signaling conversion circuit couples input current signal, and the output of signaling conversion circuit couples the input of integrating circuit, and the output of signaling conversion circuit provides output current signal.
According to another aspect of the present utility model, a kind of switch power supply system comprises: rectification circuit, has input and output, and wherein the input of rectification circuit couples AC-input voltage, and the output of rectification circuit provides input voltage; Switching circuit, has input and output, and wherein the input of switching circuit couples the output of rectification circuit, and switching circuit comprises power switch, and switching circuitry output couples load and provides output current; And control circuit as described above.
According to another aspect of the present utility model, a kind of switch power supply system, comprising: rectification circuit, has input and output, and wherein the input of rectification circuit couples AC-input voltage, and the output of rectification circuit provides input voltage; Load; Switching circuit, has input and output, and wherein the input of switching circuit couples the output of rectification circuit, and switching circuit comprises power switch, and the output of switching circuit couples load and provides output current; And control circuit, comprise integrating circuit, wherein integrating circuit has input and output, and the input of integrating circuit couples the output current signal of switching circuit, the output of integrating circuit provides charge signal, and the output of control circuit couples the control end of power switch.In one embodiment, control circuit comprises further: gain control circuit, there is first input end, the second input and output, wherein the first input end of gain control circuit couples the output of integrating circuit, second input of gain control circuit couples charge reference signal, and the output of gain control circuit provides gain modulation signal; Mlultiplying circuit, there is input, control end and output, wherein the input of mlultiplying circuit couples the input of switching circuit, and the control end of mlultiplying circuit couples the output of gain control circuit, and the output of mlultiplying circuit provides the input voltage signal through gain modulation; And ON-OFF control circuit, there is first input end, the second input and output, wherein the first input end of ON-OFF control circuit couples the output of mlultiplying circuit, second input of ON-OFF control circuit couples input current signal, and the output of ON-OFF control circuit couples the control end of power switch.In one embodiment, switching circuit comprises inverse-excitation type voltage conversion circuit.In one embodiment, switch power supply system comprises TRIAC light modulation device further, is coupled between AC-input voltage and rectification circuit.In one embodiment, load comprises LED component.
According to switch power supply system of the present utility model and control circuit thereof, effectively can eliminate the flicker problem of LED lamplight, and it is simple to have low in energy consumption, circuit, controls the advantages such as reliable.
Accompanying drawing explanation
In order to better understand the utility model, will be described in detail the utility model according to the following drawings:
Fig. 1 shows according to the AC-input voltage of the utility model one embodiment and through rectification and the input voltage waveform after rectification light modulation;
Fig. 2 shows the block diagram representation of the switch power supply system 200 according to the utility model one embodiment;
Fig. 3 shows the block diagram representation of the switch power supply system 300 according to the utility model one embodiment;
Fig. 4 shows according to the signal Vtr after light modulation of the utility model one embodiment and the waveform schematic diagram of signal Vin that obtains after rectification;
Fig. 5 shows the physical circuit schematic diagram of the switch power supply system 500 according to the utility model one embodiment;
Fig. 6 shows the schematic diagram of the charge reference signal circuit for generating 52 according to the utility model one embodiment;
Fig. 7 shows the signal waveform schematic diagram according to the utility model one embodiment;
Fig. 8 respectively illustrates in prior art the signal waveform analogous diagram of the signal waveform analogous diagram that adopts the light modulation of TRIAC device and the employing TRIAC device light modulation according to the utility model one embodiment;
Accompanying drawing does not show all circuit of embodiment or structure.The Reference numeral running through institute's drawings attached identical represents same or analogous parts or feature.
Embodiment
Describe embodiment of the present utility model with reference to the accompanying drawings in detail.It will be understood by those of skill in the art that some details in figure, if size, shape, angle and other features are only a certain specific embodiments of this technology of signal.Do not have these details, the utility model can be implemented equally.Those skilled in the art will also be understood that, although the detailed description in the utility model combines with specific embodiment, but the utility model still has other execution modes many, may some change when reality performs, but still be included in the utility model main scope, therefore, the utility model is intended to comprise all alternative, modification and the change case etc. that fall in the utility model and the scope of the said claims and purport.
Specification and " the coupling " in claims comprise and to be directly connected and by the indirect connection of intermediate.Wherein indirectly connect the connection that can comprise by conductor, this conductor has certain resistance, also can have certain parasitic capacitance value or inductance value.Indirect connection also can comprise the connection by other intermediates, as diode, switching tube, or comprises being connected of conductor and other intermediate.
Fig. 1 shows AC-input voltage Vac and the input voltage vin waveform after rectification or rectification light modulation.Switch power supply system by AC-input voltage Vac as municipal supply voltage is converted to input voltage vin through rectification.If this input voltage vin is without light modulation, then input voltage vin is as shown in waveform A.If carry out light modulation rectification to alternating voltage, carry out copped wave as adopted TRIAC device to alternating voltage Vac and pass through with the waveform controlling certain phase section, then the input voltage vin after light modulation rectification is as shown in waveform B.The cycle of the input voltage vin wherein after rectification is called input cycle T o, the i.e. half wave cycles of AC-input voltage Vac.Multiple embodiment of the present utility model by the quantity of electric charge of the output current in each input cycle T o of control switch power supply for realizing the outputting current steadily of Switching Power Supply.
Fig. 2 shows the switch power supply system 200 according to the utility model one embodiment.This switch power supply system 200 comprises rectification circuit 21, switching circuit 22, load 23 and control circuit 20.One AC-input voltage Vac rectification is formed input voltage vin by rectification circuit 21, waveform A as shown in Figure 1.Rectification circuit 21 can adopt rectifier bridge as shown in the figure, also can adopt the rectification circuit of other form.Switching circuit 22 based on input voltage vin for load 23 provide through control output current Io.In one embodiment, switching circuit 22 adopts buck converter.In some other embodiment, switching circuit also can be booster converter, isolated voltage changer or non-isolated voltage changer.In an illustrated embodiment, load 23 is LED component.In further embodiments, load 23 can be other form, can be the illuminating device of other type, also can be non-illumination device.Concerning LED, in order to make it provide stable light source, need the output current that switching circuit provides stable.Control circuit 20 receives the output current signal Ic characterizing switching circuit output current Io, and produces switch controlling signal CTRL based on this current signal Ic and be used for control switch circuit 22, thus provides required energy for load.In one embodiment, current signal Ic is obtained by direct-detection output current Io.In another embodiment, current signal Ic by obtaining after the electric current at other position of sense switch power-supply system 200 after calculating and being scaled output current again.Control circuit 20 calculates the quantity of electric charge of each input cycle output current based on current signal Ic, and controls the quantity of electric charge of the output current in each input cycle on a predeterminated level by controlling output current.Particularly, control circuit 20 comprises integrating circuit 24, charge control circuit 25 and ON-OFF control circuit 26.Integrating circuit 24 receives the output current signal Ic characterizing and flow through the output current of load 23, and carries out integration to output current signal Ic.The integrated signal that integrating circuit 24 exports is the charge signal CHG of the reflection output current quantity of electric charge.Integrating circuit 24 can adopt any existing circuit signal being carried out to integration according to the time.Charge control circuit 25 receives charge signal CHG and charge reference signal CREF, is compared by charge signal CHG and charge reference signal CREF.ON-OFF control circuit 26 based on the comparative result of charge signal CHG and charge reference signal CREF, by-pass cock control signal CTRL.In one embodiment, the comparative result of charge control circuit 25 is logical signal.In another embodiment, comparative result is error amplification signal.The turn-on and turn-off of the power switch in switch controlling signal CTRL control switch circuit 22, thus the output current of control switch circuit 22.Follow charge reference signal CREF by the electric charge controlling the output current in each input cycle, make output charge keep stable to control outputting current steadily, thus eliminate the scintillation of LED load 23 light source.
Fig. 3 shows the schematic diagram of the switch power supply system 300 according to the utility model one embodiment.Switch power supply system 300 is based on the gain of the comparative result control inputs voltage Vin of output charge and charge reference signal CREF, and based on power switch in the input voltage signal REF control switch circuit 22 of gain modulation, thus control output charge, and then control the stable of output current.Switch power supply system 300 comprises TRIAC device light adjusting circuit 31, rectification circuit 21, switching circuit 22, load 23 and control circuit 30.
Light adjusting circuit 31 has input and output, and wherein the input of light adjusting circuit 31 couples AC power Vac, and output provides the Vtr of the voltage signal after light modulation.Light adjusting circuit 31 is for carrying out the AC signal Vtr of phase place copped wave acquisition after copped wave by AC power Vac.Fig. 4 shows according to the signal Vtr after light modulation of the utility model one embodiment and the signal Vin waveform schematic diagram that obtains after rectification.TRIAC device as shown in Figure 4 adopts forward position light modulation.In another embodiment, TRIAC device also can adopt after along light modulation.Rectification circuit 21 has input and output, and wherein the input of rectification circuit 21 couples the output of light adjusting circuit 31, and for receiving the AC signal Vtr after copped wave, the output of rectification circuit 21 provides the input voltage vin of switching circuit 22.Input voltage Vtr after copped wave obtains input voltage vin through rectification circuit 21 rectification.Switching circuit 22 has input and output, and wherein input couples the output of rectification circuit 21, for receiving input voltage vin, and provides output current Io based on input voltage vin at output, for powering for load 23.In the enforcement shown in Fig. 3, control circuit 30 receives the output current signal Ic characterizing output current Io, and output current signal Ic is carried out integration by each input cycle, obtains charge signal CHG.
Control circuit 30 comprises integrating circuit 24, gain control circuit 32, mlultiplying circuit 33 and ON-OFF control circuit 26.Wherein gain control circuit 32 and mlultiplying circuit 33 can be described as charge control circuit.Integrating circuit 24 couples switching circuit 22 for receiving the output current signal Ic characterizing output current Io.Integrating circuit 24 carries out integration for obtaining charge signal CHG to output current signal Ic in an input cycle T o.Gain control circuit 32 has first input end and the second input.Wherein the first input end of gain control circuit 32 couples integrating circuit 24 for receiving charge signal CHG, second input of gain control circuit 32 receives charge reference signal CREF, gain control circuit 32 produces gain modulation signal Gct based on charge signal CHG and charge reference signal CREF, and the output of gain control circuit 32 couples the control end of mlultiplying circuit 33.Mlultiplying circuit 33 has input, control end and output, wherein the input of mlultiplying circuit 33 couples the input of switching circuit 22 for receiving the input voltage signal characterizing input voltage vin, the control end of mlultiplying circuit 33 couples the output of gain control circuit 32, and the output of mlultiplying circuit 33 provides current reference signal REF.Gain control circuit 32 based on the gain of the difference control inputs voltage Vin of integrated signal CHG and charge reference signal CREF, and obtains the input voltage signal after gain modulation as current reference signal REF.ON-OFF control circuit 26 received current reference signal REF and other feedback signals as output current signal Ic or input current signal, and based on current reference signal REF and other feedback signal output switch control signal CTRL control switch circuit 22.In one embodiment, switch power supply system 300 adopts Active PFC (PFC) to control, make input current Iin follow the waveform of the input voltage vin after gain modulation, wherein input current Iin can obtain through calculating from output current signal Ic according to the relation of the output current Io of switching circuit 22 and input current Iin.In another embodiment, ON-OFF control circuit 26 directly receives input current signal and based on through the input voltage signal REF of gain modulation and input current signal control switch circuit, makes input current Iin follow the input voltage after modulation.In yet another embodiment, current signal Ic is the signal detecting input current Iin, and input current signal Ic obtains the signal of sign output current and carries out integration for obtaining charge signal CHG to the signal after calculating after computational transformation.The control circuit 30 of switch power supply system 300 is based on the gain of the comparative result control inputs voltage Vin of charge signal CHG and charge reference signal CREF.By above-mentioned control, input current follow current reference signal REF, output charge follows charge reference signal CREF.Like this, the output charge in each input cycle is controlled in certain level, and the scintillation in the light source that LED load provides is eliminated or reduces.
Fig. 5 shows the physical circuit schematic diagram of the switch power supply system 500 according to the utility model one embodiment.Switch power supply system 500 adopts PFC to control.Switch power supply system 500 comprises light adjusting circuit 31, rectification circuit 21, switching circuit and control circuit 50.In the embodiment shown in fig. 5, switching circuit comprises inverse-excitation type voltage conversion circuit, and it comprises power switch K, transforming circuit T, secondary rectifier diode D and output capacitance C.Control circuit 50 gathers the input current Iin on the former limit of inverse-excitation type voltage conversion circuit, and controls to make the peak value of input current Iin follow input voltage vin based on PFC.Input current Iin signal is converted to the output current signal Ic characterizing output current Io by synchronous signal change-over circuit 51, and controls the charge stable of output current Io within each input cycle.
Control circuit 50 comprise current feedback circuit, signaling conversion circuit 51, integrating circuit 24, charge reference signal circuit for generating 52, electric charge comparison circuit 53, gain modulation circuit 54, first latch cicuit 59, mlultiplying circuit 33, with door 57 and ON-OFF control circuit.Wherein ON-OFF control circuit comprises current comparison circuit 55 and the second latch cicuit 56.Control circuit 50 comprises testing circuit 58 further, detects the state of input voltage vin.In one embodiment, when input voltage vin saltus step, as input voltage vin be high voltage by null value saltus step time, testing circuit 58 exports the pulse of high level for characterizing the arrival in new input cycle, and wherein charge signal CHG is that output current signal in the input cycle is to the integration of time.In the illustrated embodiment in which, the light modulation of TRIAC device adopts forward position light modulation, state detection signal Det exports high level pulse when input voltage vin is high voltage by null value saltus step, one of them input cycle be state detection signal Det two rising edge of a pulses between time long.In another embodiment, along light modulation after TRIAC device adopts, then the time between state detection signal two rising edge of a pulses when input cycle, to be input voltage switched to null value by high potential is long.Current feedback circuit comprises resistance R and lead-edge-blanking circuit LEB, for the electric current of sample streams overpower K switch, i.e. and input current Iin, and input current signal Ii is provided.The input of signaling conversion circuit 51 couples current feedback circuit for receiving input current signal Ii.Signaling conversion circuit 51 calculates output current Io based on input current Iin, and provides output current signal Ic at the output of signaling conversion circuit 51.In another embodiment, output current signal Ic is obtained by sampling secondary output current.The input of integrating circuit 24 couples the output of signaling conversion circuit 51 for receiving output current signal Ic, carries out integration, and provide charge signal CHG at the output of integrating circuit 24 to output current signal Ic within an input cycle along the time.Charge reference signal circuit for generating 52 produces charge reference signal CREF.In one embodiment, charge reference signal circuit for generating 52 produces charge reference signal CREF based on input voltage vin mean value in cycles.
Fig. 6 shows the schematic diagram of the charge reference signal circuit for generating 52 according to the utility model one embodiment.Charge reference signal circuit for generating 52 comprises low pass filter 61 and clamps down on circuit 62.Wherein the input of low pass filter 61 receives input voltage vin, and low pass filter 61 pairs of input voltages carry out low-pass filtering, to obtain the mean value of input voltage vin within a time period.In one embodiment, this time period is n input cycle, wherein n be greater than 2 positive integer.The output of low pass filter 61 couples clamps down on circuit 62.Clamp down on circuit 62 upgrades output filter circuit 61 filter value at the terminal of each time period.Low pass filter 61 can adopt the circuit arbitrarily with low-pass filtering function.Clamp down on circuit 62 and can be the circuit arbitrarily with maintenance-output function.
Continue the explanation of Fig. 5.Electric charge comparison circuit 53 has in-phase input end, inverting input and output, wherein the in-phase input end of electric charge comparison circuit 53 couples the output of integrating circuit 24 for receiving integrated signal CHG, and the inverting input of electric charge comparison circuit 53 couples the output of charge reference signal circuit for generating 52 for receiving charge reference signal CREF.Integrated signal CHG and charge reference signal CREF compares by electric charge comparison circuit 53, output charge comparison signal Ccmp.In another embodiment, the signal of in-phase input end and inverting input can be exchanged.The input of gain modulation circuit 54 couples the output of electric charge comparison circuit 53, its output couples the control end of mlultiplying circuit 33, gain modulation circuit 54 produces gain modulation signal Ginc based on electric charge comparison signal Ccmp, the gain of Gdec to input voltage vin is modulated, and provide the input voltage signal after modulation, as the current reference signal REF of input current Iin at the output of mlultiplying circuit 33.In one embodiment, gain modulation circuit 54 output gain rising signals Ginc and gain dropping signal Gdec two logical signals, when gain rising signals Ginc be effective status, gain dropping signal Gdec be disarmed state time, gain is increased; When gain rising signals Ginc be disarmed state, gain dropping signal Gdec be effective status time, gain reduction; When gain rising signals Ginc and gain dropping signal Gdec is effective status or disarmed state, gain is constant.Electric charge comparison signal Ccmp is delivered to the first latch cicuit 59 further for controlling switch-off power K switch at charge signal CHG higher than during charge reference signal CREF.First latch cicuit 59 has the RESET input R, set input S and output Q, and wherein the RESET input R couples the output of electric charge comparison circuit 53, and set input S couples the output of testing circuit 58 for accepting state detection signal Det.The output Q of the first latch cicuit 59 couples the first input end with door 57.When charge signal CHG is greater than charge reference signal CREF, electric charge comparison signal Ccmp is effective high level signal, resetted by first latch cicuit 59, the signal of the output Q output low level of the first latch cicuit 59, turns off power switch K with door 57 output low level signal simultaneously.When the next one input cycle arrives, there is high level pulse in state detection signal Det, the first latch cicuit 59 set, its output Q is high level, and the output signal of AND circuit 57 controls by ON-OFF control circuit.In one embodiment, switch power supply system 500 comprises drive circuit further between door 57 and power switch K, is used for driving power K switch for logical signal being enlarged into suitable voltage.Wherein charge reference signal circuit for generating 52, electric charge comparison circuit 53, gain modulation circuit 54, mlultiplying circuit 33, first latch cicuit 59 and can merge with door 57 and be called charge control circuit, electric charge comparison circuit 53 and gain modulation circuit 54 can merge and be called gain control circuit.
In another embodiment, gain control circuit comprises error amplifying circuit further, obtains error signal for the difference of charge signal CHG and charge reference signal CREF being amplified, and based on the gain of this error signal control inputs voltage Vin.
When charge signal CHG is higher than charge reference signal CREF, electric charge comparison signal Ccmp is logic-high signal, and gain modulation circuit 54 reduces the gain of input voltage vin, for reducing current reference signal REF; When charge signal CHG one input the cycle all lower than charge reference signal CREF time, electric charge comparison signal Ccmp is logic-low signal, and gain modulation circuit 54 raises the gain of input voltage vin, for elevated currents reference signal REF.
Current comparison circuit 55 has in-phase input end, inverting input and output.Wherein in-phase input end couples current feedback circuit for receiving input current signal Ii, inverting input couples mlultiplying circuit 33 for received current reference signal REF, current comparison circuit 55 compares input current signal Ii and current reference signal REF, and provides electric current comparison signal Icmp.The output of current comparison circuit 55 is for controlling the power switch K of inverse-excitation type voltage conversion circuit.Second latch cicuit 56 has set input S, the RESET input R and output Q, wherein set input S receives asserts signal ON, the RESET input couples the output of current comparison circuit 55, and output Q is coupled to the control end of power switch K by drive circuit.When asserts signal ON is effective status, during as high level current potential, the output Q of the second latch cicuit 56 provides the signal of high level for conducting power switch K.Asserts signal ON is the "or" signal of the zero current detection signal ZCD of state detection signal Det and input current Iin, and namely when input current Iin reduces to zero or the new input cycle arrives, asserts signal ON is that effective status is for set second latch cicuit 56.In another embodiment, asserts signal ON produces based on the signal of other type being different from zero current detection signal.When input current signal Ii rises to current reference signal REF, comparison circuit 55 exports effective high level signal, and the second latch cicuit 56 is reset output low level signal, and power switch K is turned off.Also namely input current signal Ii and the input voltage signal after gain modulation and current reference signal REF compare by comparison circuit 55, switch-off power K switch when making the peak value as input current signal Ii arrive current reference signal REF, thus the peak value of control inputs current signal Ii follows the input voltage signal REF after gain modulation.Output current signal Ic, through integrating circuit 24 integration, obtains the charge signal CHG in the input cycle.This charge signal CHG is compared with charge reference signal CREF, and the gain of result Ccmp control inputs voltage Vin based on the comparison, by the cycle Charge controlled of output current Io in charge reference signal CREF level, thus obtain stable output current, eliminate the scintillation in output current.
Fig. 7 shows the signal waveform schematic diagram according to the utility model one embodiment.These signals comprise the input signal Vin shown in Fig. 5 circuit diagram, input current signal Iin, current reference signal REF, charge reference signal CREF, charge signal CHG and electric charge comparison signal Ccmp, and the gain modulation coefficient Gain of gain dropping signal Gdec, gain rising signals Ginc and input voltage vin in gain modulation circuit 54.These signals of contact are set forth the working method according to control circuit 50 in Fig. 5 of an embodiment below.
At time t0, light adjusting circuit starts conducting, and input voltage vin rises to high level by zero potential, and high level pulse appears in state detection signal Det, and an input cycle starts.Now there is effective status in asserts signal ON, and latch cicuit 56 is set, and switch controlling signal CTRL switches to high level, power switch K conducting, and input current Iin starts to rise.The rising of input current Iin causes the rising of output current, and the charge signal CHG of output current starts to rise.When input current Iin rises to current reference signal REF, switch controlling signal CTRL switches to low level, and power switch K turns off, and now input current Iin declines after there is peak value.When input current Iin drops to null value, namely when there is high level pulse in zero current detection signal ZCD, asserts signal ON switches to effective status, switch controlling signal CTRL is set to high level, input current Iin rises again, until input current Iin arrives current reference signal REF again, switch controlling signal CTRL switches to low level again, and input current Iin reaches peak value again.Along with the decline of input voltage vin, the peak value of input current Iin also declines thereupon, and meanwhile, the charge signal CREF of output current rises gradually but the rate of climb slows down.Can see, the peak value of input current signal Ii follows the waveform of input voltage signal through gain modulation and current reference signal REF, achieves PFC and controls.At time t1, charge signal CHG rises to higher than charge reference signal CREF, and electric charge comparison signal Ccmp switches to effective high level.The electric charge comparison signal Ccmp of high level makes the first latch cicuit 59 in Fig. 5 reset, with the switch controlling signal CTRL of door 57 output low level, and switch-off power K switch.Although now input voltage vin is not down to null value, input current Iin reduces to null value, and the output current electric charge CHG in this cycle is controlled in charge reference signal CREF level.Meanwhile, gain dropping signal Gdec switches to effective high level from invalid low level, and input voltage gain G ain starts to decline.At time t2, input voltage vin reduces to predetermined reference voltage Vth, and gain rising signals Ginc switches to the effective status of high level, and gain decline and gain are risen and offseted, and input voltage gain G ain keeps level.At time t3, light adjusting circuit TRIAC break-over of device, input voltage vin rises to high level by null value, and high level pulse appears in state detection signal Det, another input cycle arrives, and gain rising signals Ginc and gain dropping signal Gdec switches to low level disarmed state simultaneously.Now, asserts signal ON switches to effective status, and the second latch cicuit 56 is set, power switch K conducting again.Like this, there is decline first input cycle (t0-t3) in gain G ain.At time t4, input voltage vin drops to predetermined reference voltage Vth, and gain rising signals Ginc switches to high level.At time t5, input voltage drops to null value, and gain dropping signal Gdec switches to high level.In one embodiment, when input voltage drops to a lower reference voltage Vth2, gain dropping signal Gdec switches to high level, wherein Vth2<Vth.Like this, between time period t 4 to t5, gain rising signals Ginc is high level, and gain dropping signal Gdec is low level, and the gain G ain of input voltage vin rises.When next cycle arrives, at time t6, at the rising edge of state detection signal Det pulse, gain rising signals Ginc and gain dropping signal Gdec switches to low level simultaneously.Like this, between time t4 and t5, gain signal Gain rises, and ensure that the rising of input voltage gain in the next input cycle.If input voltage vin spoke value is less, moment t4 arrive more early, then the rise time (t4-t5) of gain G ain is longer, then input voltage gain G ain rising larger.The charge signal CHG controlling output current thus follows charge reference signal CREF.
Fig. 8 respectively illustrates in prior art the signal waveform analogous diagram (see right figure) of the signal waveform analogous diagram (seeing left image) that adopts the light modulation of TRIAC device and the employing TRIAC device light modulation according to the utility model one embodiment.Illustrated oscillogram adopts the light modulation of TRIAC device, the light modulation of TRIAC device has fluctuation opportunity in the different input cycles, therefore the phase fluctuation of input voltage vin and the change of amplitude is caused, to be later than the input voltage vin in first input cycle opportunity as the input voltage vin light modulation in second input cycle, therefore second input voltage vin amplitude is less than the input voltage amplitude in the period 1.In the prior art, the peak value of input current Iin follows input voltage vin completely, and when input voltage vin amplitude reduces, the electric charge CHG of output current also declines in adjacent two input cycles, consequently leads to the scintillation of LED.And according to the switch power supply system of the utility model one embodiment, its power switch turns off after charge signal CHG arrives charge reference signal, input current Iin is made to reduce to null value in time.Therefore during ensure that different input week, charge peak is stable, therefore effectively can avoid the scintillation of LED.
It should be known that the effective status of a signal can be high level state, also can be low level state, the disarmed state of this signal is contrary state with effective status simultaneously.The in-phase input end of a logical circuit and inverting input or also can exchange between set input and the RESET input, adjust other logical circuit for realizing identical allomeric function simultaneously.
Some above-mentioned specific embodiments are only described the utility model in an exemplary fashion, and these embodiments are not completely detailed, and are not used in restriction scope of the present utility model.It is all possible for carrying out changing and revising for disclosed embodiment, other feasible selectivity embodiments and to the equivalent variations of element in embodiment can understand by those skilled in the art.Other changes of embodiment disclosed in the utility model and amendment do not exceed spirit of the present utility model and protection range.
Claims (13)
1., for a control circuit for control switch circuit, comprising:
Integrating circuit, has input and output, and wherein input couples the output current signal characterizing switching circuit output current, and output provides charge signal;
Charge control circuit, have first input end, the second input and output, wherein the first input end of charge control circuit couples charge signal, and the second input of charge control circuit couples charge reference signal; And
ON-OFF control circuit, has input and output, and wherein the input of ON-OFF control circuit couples the output of charge control circuit, and the output of ON-OFF control circuit provides switch controlling signal to the control end of the power switch of switching circuit.
2. control circuit as claimed in claim 1, wherein charge control circuit comprises:
Gain control circuit, there is first input end, the second input and output, wherein the first input end of gain control circuit couples charge signal, and the second input of gain control circuit couples charge reference signal, and the output of gain control circuit provides gain modulation signal; And
Mlultiplying circuit, there is input, control end and output, wherein the input of mlultiplying circuit couples the input of switching circuit, the control end of mlultiplying circuit couples the output of gain control circuit, the output of mlultiplying circuit couples the input of ON-OFF control circuit, and the output of mlultiplying circuit provides the input voltage signal through gain modulation.
3. control circuit as claimed in claim 2, comprise current feedback circuit further, current feedback circuit couples the input of switching circuit and provides input current signal, and when input current signal is greater than the input voltage signal through gain modulation, power switch is off state.
4. control circuit as claimed in claim 1, wherein charge control circuit comprises:
Charge reference signal circuit for generating, has input and output, and the output of charge reference signal circuit for generating provides charge reference signal;
Electric charge comparison circuit, there is first input end, the second input and output, wherein first input end couples the output of integrating circuit, and the second input couples the output of charge reference signal circuit for generating, and the output of electric charge comparison circuit provides electric charge comparison signal;
Gain modulation circuit, has input and output, and the input of gain modulation circuit couples the output of electric charge comparison circuit, and the output of gain modulation circuit provides gain modulation signal;
Mlultiplying circuit, has input, control end and output, and wherein the input of mlultiplying circuit couples the input of switching circuit, and the control end of mlultiplying circuit couples the output of gain modulation circuit, and the output of mlultiplying circuit provides current reference signal;
First latch cicuit, has set input, the RESET input and output, and wherein the set input of the first latch cicuit couples input voltage measurement signal, and the RESET input of the first latch cicuit couples the output of electric charge comparison circuit; And
With door, there is first input end, the second input and output, wherein couple the output of ON-OFF control circuit with the first input end of door, couple the output of the first latch cicuit with the second input of door, couple the control end of power switch with the output of door.
5. control circuit as claimed in claim 4, wherein ON-OFF control circuit comprises:
Current comparison circuit, there is first input end, the second input and output, wherein the first input end of current comparison circuit couples the output of mlultiplying circuit, and the second input of current comparison circuit couples input current signal, and the output of current comparison circuit provides electric current comparison signal; And
Second latch cicuit, have set input, the RESET input and output, wherein set input couples asserts signal, and the RESET input couples the output of current comparison circuit, and the output of the second latch cicuit couples the first input end with door.
6. control circuit as claimed in claim 4, wherein charge reference signal circuit for generating comprises:
Low pass filter, has input and output, and wherein the input of low pass filter couples the input of switching circuit; And
Clamp down on circuit, have input and output, the input wherein clamping down on circuit couples the output of low pass filter, and the output clamping down on circuit provides charge reference signal.
7. control circuit as claimed in claim 1, comprise signaling conversion circuit further, the input of signaling conversion circuit couples input current signal, and the output of signaling conversion circuit couples the input of integrating circuit, and the output of signaling conversion circuit provides output current signal.
8. a switch power supply system, comprising:
Rectification circuit, has input and output, and wherein the input of rectification circuit couples AC-input voltage, and the output of rectification circuit provides input voltage;
Switching circuit, has input and output, and wherein the input of switching circuit couples the output of rectification circuit, and switching circuit comprises power switch, and switching circuitry output couples load and provides output current; And
As the control circuit as described in arbitrary in claim the 1-7.
9. a switch power supply system, comprising:
Rectification circuit, has input and output, and wherein the input of rectification circuit couples AC-input voltage, and the output of rectification circuit provides input voltage;
Load;
Switching circuit, has input and output, and wherein the input of switching circuit couples the output of rectification circuit, and switching circuit comprises power switch, and the output of switching circuit couples load and provides output current; And
Control circuit, comprise integrating circuit, wherein integrating circuit has input and output, and the input of integrating circuit couples the output current signal of switching circuit, the output of integrating circuit provides charge signal, and the output of control circuit couples the control end of power switch.
10. switch power supply system as claimed in claim 9, wherein control circuit comprises further:
Gain control circuit, there is first input end, the second input and output, wherein the first input end of gain control circuit couples the output of integrating circuit, and the second input of gain control circuit couples charge reference signal, and the output of gain control circuit provides gain modulation signal;
Mlultiplying circuit, there is input, control end and output, wherein the input of mlultiplying circuit couples the input of switching circuit, and the control end of mlultiplying circuit couples the output of gain control circuit, and the output of mlultiplying circuit provides the input voltage signal through gain modulation; And
ON-OFF control circuit, there is first input end, the second input and output, wherein the first input end of ON-OFF control circuit couples the output of mlultiplying circuit, second input of ON-OFF control circuit couples input current signal, and the output of ON-OFF control circuit couples the control end of power switch.
11. switch power supply systems as claimed in claim 9, wherein switching circuit comprises inverse-excitation type voltage conversion circuit.
12. switch power supply systems as claimed in claim 9, comprise TRIAC light modulation device further, are coupled between AC-input voltage and rectification circuit.
13. switch power supply systems as claimed in claim 9, wherein load comprises LED component.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201420836164.3U CN204290732U (en) | 2014-12-25 | 2014-12-25 | Switching power supply system and control circuit thereof |
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| CN201420836164.3U CN204290732U (en) | 2014-12-25 | 2014-12-25 | Switching power supply system and control circuit thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104578799A (en) * | 2014-12-25 | 2015-04-29 | 成都芯源系统有限公司 | Switching power supply system and control circuit and control method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104578799A (en) * | 2014-12-25 | 2015-04-29 | 成都芯源系统有限公司 | Switching power supply system and control circuit and control method thereof |
| CN104578799B (en) * | 2014-12-25 | 2017-04-12 | 成都芯源系统有限公司 | Switching power supply system and control circuit and control method thereof |
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