CN105897009A - AC-DC converter and method thereof - Google Patents
AC-DC converter and method thereof Download PDFInfo
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- CN105897009A CN105897009A CN201510078564.1A CN201510078564A CN105897009A CN 105897009 A CN105897009 A CN 105897009A CN 201510078564 A CN201510078564 A CN 201510078564A CN 105897009 A CN105897009 A CN 105897009A
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Abstract
The present application discloses an AC-DC converter and a method thereof. The AC-DC converter comprises an input port which is coupled to AC voltage, a rectifier coupled to the input port and converts the AC voltage into periodical DC voltage, an output port which provides current and voltage to a load, an output capacitor which is coupled to the output port, a high voltage switch which is connected to the output capacitor in series to coupled to the rectifier, has a first state and a second state and is used for stopping or allowing the rectifier to transmit charge to the output port, and a controller which has an output end, a voltage detection end and a current detection end and is coupled to the high voltage switch. The controller detects the power port voltage of the high voltage switch and determines the time of switching to a second state from a first state of the high voltage switch, and determines the time of switching to the first state from the second state of the high voltage switch through the charge amount of the high voltage switch when a condition that the high voltage switch is in the second state is detected. The AC-DC converter output constant average current, the structure is simple, and the cost is low.
Description
Technical field
The present invention relates to AC-DC converter technology, especially, the present invention relates to a kind of driving high voltage-small current luminous
The power technology of diode.
Background technology
LED lighting is high (50～200Lm/W) with its light efficiency, and life-span length (theoretical value reaches 100,000 hours) does not contains
The harmful substance such as mercury, lead, is used widely in recent years without features such as infrared and ultraviolet pollutions, the most progressively replaces traditional white heat
Lamp and electricity-saving lamp, become emerging green light source.
Drive lumination of light emitting diode need the anode of diode and negative electrode be applied more than its forward conduction voltage (Vf,
Single diode is about 3.3V) voltage and specified electric current is provided.In order to increase the brightness of light source, it is used as the luminescence two of illumination
Pipe many forms with connection in series-parallel array in pole use.In order to ensure the uniformity of luminosity, extend the use longevity of light emitting diode
Life, the feature that the power supply of driving light emitting diode is important is to export constant electric current.As long as flowing through the light-emitting diodes of same model
The electric current of pipe is identical, and the brightness of light emitting diode is the most identical, and the emission uniformity of the light emitting diode being therefore used in series is best.
Even if the electric current flowing through the light emitting diode of same model is identical, the forward conduction voltage of this model light emitting diode Different Individual
Still there is bigger distribution, thus drive the load voltage of the constant-current supply of light emitting diode to have bigger excursion.Therefore,
The power supply driving light emitting diode needs be operated in constant current mode rather than be operated in constant voltage mode.Only in the (example that breaks down
Such as light-emitting diode open-circuit) time, it is desirable to drive the output of power supply not can exceed that a upper voltage limit, in case locking system element occurs
The consequences such as overstress inefficacy.Therefore, preferable LED driving power needs to export constant electric current, and is breaking down
Time have limit load voltage function.
Fig. 1 is the dynamic characteristic of preferable LED driving power.When load voltage is less than limiting voltage
(Vov), during point, the average output current (ILmean) that power supply output is constant is driven.When load voltage reaches to limit voltage (Vov)
Time, reduce until not providing output electric current.
Along with the continuous progress of LED lighting technology, at light emitting diode T spot, filament lamp and bulb lamp light source
In, gradually, the operating current of illuminator is the least, and operating voltage is more and more higher for the light emitting diode number being used in series.Example
As, the 3.5W light emitting diode filament of a kind of 220V of being applicable to alternating current needs the constant current of 20mA to drive, and Typical operating voltages exists
Near 150V, the ILmean of corresponding diagram 1 be 20mA, VL representative value be 150V, Vov be 200V.
Use Switching Power Supply step-down mode can realize the current-voltage characteristic curve required by Fig. 1.Switching Power Supply scheme
Output current precision and conversion efficiency higher, but for the power-supply system of 150V/20mA from the point of view of, element is more, inductance volume
Relatively big, relatively costly, HF switch can bring electromagnetic compatibility problem.
Prior art drive high voltage small area analysis LED power source usually use the resistance-capacitance depressurization mode shown in Fig. 2
Realize the current-voltage characteristic curve required by Fig. 1.Such as Fig. 2, the effect of electric capacity 22 (capacitance is C) is step-down and current limliting.When defeated
Entering the frequency of alternating current when being f, the capacitive reactance of electric capacity 22 is
Xc=1/ (2 π f C) (1)
The effect that this capacitive reactance can be played and limit output electric current, share alternating voltage.In Fig. 2, resistance 21 disconnects for alternating current
The offer path of releasing of electric charge on rear electric capacity 22, Zener diode 24 acts the effect of voltage in load capacitance 25 that limits.Electric capacity 22
The deviation of capacitance, the deviation of light emitting diode forward voltage drop, the fluctuation of input ac voltage all can affect the big of output electric current IL
Little, thus the power supply shown in Fig. 2 cannot obtain the constant-current characteristics that Fig. 1 requires.
Prior art drive high voltage small area analysis LED power source the most usually use the linear constant current mode of Fig. 3 in fact
Existing current-voltage characteristic curve required by Fig. 1.As it is shown on figure 3, constant-current source circuit 34 with load 33 connect after with electric capacity 32 also
Connection, makes to flow through the constant current hold of load.The advantage that linear constant current has constant current accuracy height, system element is few, but requirement
Input ac voltage light emitting diode forward conduction voltage sum stable, series connection has good uniformity, and guarantee is managed
The conversion efficiency thought.When input ac voltage fluctuate, light emitting diode forward conduction voltage sum distribution bigger time, constant current
The problems such as the power that source 34 consumes is excessive, power supply conversion efficiency is relatively low, affect power-supply system and the reliability of light source and life-span.
Summary of the invention
It is an object of the invention to overcome the shortcoming of prior art, it is provided that one has constant output current, high conversion effect
Rate, permission input ac voltage and load voltage have larger fluctuation, have the AC-DC converter of load open circuit protection function
According to embodiments of the invention, it is proposed that a kind of AC-DC converter, including: input port, it coupled to exchange
Voltage；Rectifier, coupled to input port, and alternating voltage is converted to periodically DC voltage；Output port, provides to load
Electric current and voltage；Output capacitance, coupled to output port；High-voltage switch gear, is coupled in series to rectifier with output capacitance；Described height
Compress switch and there is power port and control end, be operated in the first state and the second state, when high-voltage switch gear is in the first state,
Described high-voltage switch gear stops rectifier to transmit electric charge to output port, and when high-voltage switch gear is in the second state, described height presses off
Close and allow rectifier to transmit electric charge to output port；Controller, has voltage detecting end and the electric current of output, independence or multiplexing
Test side, coupled to high-voltage switch gear；Described controller is determined by the power port voltage of voltage detecting end detection high-voltage switch gear
Described high-voltage switch gear switches to the moment of the second state from the first state, and described controller detects described height by current detecting end
Compress switch by the quantity of electric charge of high-voltage switch gear when being in the second state, determine that high-voltage switch gear switches to the first state from the second state
Moment；The average current that the output of described AC-DC converter is constant, simple in construction, with low cost.
According to embodiments of the invention, it is proposed that a kind of AC-DC converter, the control of described AC-DC converter
Device processed detects the power port voltage of described high-voltage switch gear within each cycle of described DC voltage, when described high-voltage switch gear
High-voltage switch gear is switched to the second state from the first state less than controller during the first predeterminated voltage by power port voltage；When described
When high-voltage switch gear is in the second state, when by the quantity of electric charge of described high-voltage switch gear reach first preset the quantity of electric charge time described control
High-voltage switch gear is switched to the first state from the second state by device；Described controller makes constant the putting down of AC-DC converter output
All load currents.
According to embodiments of the invention, it is also proposed that a kind of AC-DC converter, described AC-DC converter
Controller detects the power port voltage of high-voltage switch gear within each cycle of DC voltage, when merit high-voltage switch gear being detected
Rate port voltage is more than after the second predeterminated voltage, when described high-voltage switch gear power port voltage is less than the first predeterminated voltage time control
High-voltage switch gear is switched to the second state from the first state by device processed；When described high-voltage switch gear is in the second state, when passing through
State the quantity of electric charge of high-voltage switch gear to reach the first described controller when presetting the quantity of electric charge from the second state, high-voltage switch gear is switched to
One state；It is constant that described controller makes AC-DC converter export under conditions of load voltage is less than the 3rd predeterminated voltage
Average load current, there is load open circuit protection function.
According to embodiments of the invention, it is also proposed that a kind of method for controlling AC-DC converter output electric current,
Including: it is periodic DC voltage by ac voltage rectifier；Wait that a DC voltage cycle starts；Judge described direct current
Whether pressure adds predeterminated voltage less than output voltage, if DC voltage adds predeterminated voltage less than output voltage, from DC voltage to
Output port transmission electric charge, when transmitting the quantity of electric charge and reaching preset value, terminates electric charge transmission, waits the next DC voltage cycle
Start；If described DC voltage adds predeterminated voltage higher than output voltage, wait described DC voltage step-down；
Above-mentioned AC-DC converter based on the present invention and method thereof, have the constant average load current of output, permit
Permitted input ac voltage and load voltage is had larger fluctuation, conversion efficiency height, has the features such as load voltage open-circuit-protection, circuit
Simple in construction, with low cost.
Accompanying drawing explanation
Fig. 1 is the i-v curve preferably driving LED power source
Fig. 2 is the schematic diagram of resistance-capacitance depressurization AC-DC converter 20 based on prior art；
Fig. 3 is the schematic diagram of linear constant current AC-DC converter 30 based on prior art；
Fig. 4 is the schematic diagram of AC-DC converter 40 based on one embodiment of the invention；
Fig. 5 is the circuit diagram of controller 47 based on Fig. 4 embodiment of the present invention；
Fig. 6 is the schematic diagram of a kind of rising edge monopulse generator needed for Fig. 5；
Fig. 7 is oscillogram based on the AC-DC converter main node shown in Fig. 4 to Fig. 6 of the present invention；
Fig. 8 is the schematic diagram of AC-DC converter 50 based on another embodiment of the present invention；
Fig. 9 is the oscillogram of AC-DC converter main node based on Fig. 8 embodiment of the present invention；
Figure 10 is the method stream of the AC-DC converter of a kind of constant average output current based on the embodiment of the present invention
Cheng Tu；
Detailed description of the invention
The specific embodiment of the present invention described in detail below.The example of embodiment is given in the accompanying drawings.It should be noted that, here
The example described is used only to illustrate, and is not limited to the present invention.For the ease of thoroughly understanding the present invention, elaborate big
The specific detail of amount.But, for persons skilled in the art it is readily apparent that need not use these details can also be real
Execute the present invention.In describing the embodiments of the present, in order to avoid obscuring the present invention, circuit well-known in the art is specifically retouched
State.
Throughout the specification, " embodiment ", " embodiment ", " example " or " example " is mentioned meaning
, the special characteristic, structure or the characteristic that describe in conjunction with this embodiment or example are comprised at least one enforcement of the present invention
In example.Therefore, each of entire disclosure local occur phrase " in one embodiment ", " in an embodiment ", " one
Example " or " example " be not necessarily all referring to same embodiment or example.Furthermore, it is possible to any suitable combination and (or) son
Combine specific feature, structure or property combination in one or more embodiment or example.Therefore, this area
Those skilled in the art should be appreciated that accompanying drawing is provided to illustration purpose provided herein, and accompanying drawing is not necessarily to scale
Draw.Should be appreciated that it may be coupled directly to another element, it is also possible to deposits when claiming element " to be coupled to " another element
In intermediary element.On the contrary, when claiming element " to be directly coupled to " another element, there is not intermediary element.Same or similar attached
Figure mark represents same or similar element or has the element of same or like operation.
Fig. 4 is the topological structure schematic diagram of the AC-DC converter 40 according to one embodiment of the invention.As shown in Figure 4,
AC-DC converter 40 includes: input port, coupled to alternating voltage Vac；Rectifier 41, coupled to input port, will hand over
Stream voltage Vac is converted to periodic DC voltage Vdc；Output port, to load 43 offer electric current IL and voltage VL；Output electricity
Hold 42, coupled to output port；High-voltage MOS transistor 44, has control end grid (G) and power end drain electrode (D) and source electrode
(S), it is power port between its drain electrode (D) and source electrode (S), connects with output capacitance 42, coupled to DC voltage Vdc；High pressure
MOS transistor 44 has two kinds of duties: the first state is cut-off state, and the second state is conducting state, and cut-off state is used
In stoping rectifier 41 to output capacitance 42 and load 43 transmission electric charge, conducting state is used for allowing rectifier 41 to output capacitance
42 transmit electric charges with load 43；First divider resistance 46, coupled to power port (drain terminal and the source of high-voltage MOS transistor 44
End), for detecting the power port voltage VDS of high-voltage MOS transistor 44；If high-voltage MOS pipe 44 is in the second state and (leads
Logical) time its power port voltage VDS relatively low, then can reduce the conduction loss of high-voltage MOS pipe 44；Current sense resistor 45, coupling
It is bonded to the source electrode (S) of high-voltage MOS transistor 44 and with reference between ground, is used for detecting high-voltage MOS transistor 44 and is in the second state
Under (conducting) flow through the electric current of high-voltage MOS transistor 44, and then obtain the quantity of electric charge by high-voltage MOS transistor 44；
AC-DC converter 40 shown in Fig. 4 also includes: controller 47, has voltage detecting end VS, current detecting end
CS and output OUT, OUT coupled to control end grid (G) of high-voltage MOS transistor 44, and voltage detecting end VS coupled to first
The tap of divider resistance 46, controller 47, by the power port voltage VDS of VS end detection high-voltage MOS transistor 44, determines height
Pressure MOS transistor 44 switches to the moment of conducting state from cut-off state；Controller 47 is by the electricity on CS end detection resistance 45
Pressure, draws the electric current Ics flowing through high-voltage MOS transistor 44, obtains Ics ON time integration passing through high pressure under conducting state
The quantity of electric charge of MOS transistor 44, determines that high-voltage MOS transistor 44 switches to the moment of cut-off state from conducting state.
AC-DC converter 40 shown in Fig. 4 farther includes: the first storage capacitor 49, coupled to controller 47
Feeder ear VCC；First starts resistance 48, coupled to rectifier 41 and the first storage capacitor 49, makes the direct current that rectifier 41 exports
Voltage Vdc is that the first storage capacitor 49 is powered, and the parasitic capacitance for existing between rectifier 41 output and reference ground carries simultaneously
For discharge path, Vdc voltage is made to follow alternating voltage Vac change when higher than load voltage VL；AC-DC shown in Fig. 4
Converter 40 uses low limit to control, and high-voltage MOS transistor 44 is positioned at below output capacitance, uses raster data model.
For LED load, as it is shown in figure 1, need AC-DC converter 40 to export constant average load
Electric current ILmean (the such as 20mA shown in Fig. 1).According to the definition of average current, as long as by load in Fixed Time Interval
The quantity of electric charge be constant, then average load current is exactly constant.In the embodiment of the present invention shown in Fig. 4, rectifier 41
Output voltage Vdc there is the cycle T as alternating voltage Vac, as long as ensure in the cycle T of a Vdc by load
Electric charge be constant, then average load current is exactly constant.
From the AC-DC converter topological structure of the present invention shown in Fig. 4 it can be seen that pass to the institute of input port
Electric charge is had to derive from the output voltage Vdc of rectifier 41.Ignore the electric current (being far smaller than load current IL) flowing through resistance 46,
It is transferred to the electric charge loading 43 from DC voltage Vdc and all passes through high-voltage switch gear with the charging charge being stored in output capacitance 42
44.When load voltage VL is in stable state, the charging charge of output capacitance is equal to the discharge charge by load, therefore, as long as
Controlling in a cycle T of DC voltage Vdc by the quantity of electric charge of high-voltage MOS transistor 44 is the first preset value Q, it is possible to
Obtain constant average load current ILmean.AC-DC converter based on embodiment of the present invention Fig. 4 averagely export electricity
Stream precision is better than the AC-DC converter based on existing resistance-capacitance depressurization technology shown in Fig. 2.
In the embodiment of the present invention shown in Fig. 4, the output voltage Vdc of rectifier 41 is in load voltage VL and maximum
Cyclically-varying between VdcMax, when Vdc voltage is close to VL voltage, the power port voltage VDS of high-voltage MOS transistor 44 is very
Low, the conduction loss of high-voltage MOS transistor can be reduced in this period to output port transmission electric charge.For driving high voltage
Small area analysis LED lighting is applied, such as the 150V/20mA typical case's application shown in Fig. 1, can be by the time of transmission electric charge
Concentrate on the high-voltage MOS transistor 44 power port voltage VDS less period.And, friendship based on Fig. 4 embodiment of the present invention
Stream-direct current converter, divides more greatly when the amplitude of input ac voltage occurs the voltage VL of fluctuation or LED load to have
During cloth, only high-voltage MOS transistor transmission electric charge time be engraved in the DC voltage Vdc cycle relative position change, negative
Current-carrying precision and conversion efficiency are unaffected, therefore, and turning of AC-DC converter based on Fig. 4 embodiment of the present invention
Change efficiency to be better than based on linear constant current technical scheme existing shown in Fig. 3.
Fig. 5 is the circuit diagram of the AC-DC converter controller 47 of the embodiment of the present invention shown in Fig. 4.Such as Fig. 5
Shown in, controller 47 includes: the first rest-set flip-flop 478, has the first stable state (OUT=0), corresponding diagram 4 high-voltage MOS transistor 44
Being in cut-off state, the second stable state (OUT=1), corresponding diagram 4 high-voltage MOS transistor 44 is in the conduction state；First anti-phase time delay
Circuit 480 coupled to discharge switch 481 after anti-phase for controller output end OUT time delay, in the cycle of each DC voltage Vdc
For integrating capacitor 482 predeterminated voltage initial value；Second rest-set flip-flop 479, has three-stable state (VL_NORMAL=0), represents load
Voltage VL overvoltage malfunctions such as (corresponding) load open circuits, and the 4th stable state (VL_NORMAL=1), represent load voltage VL
Normally；
As it is shown in figure 5, controller 47 also includes: the first comparator 471, it coupled to controller voltage detecting end VS, be used for
(corresponding VS voltage is less than the first ginseng to judge power port voltage VDS the most as little as first predeterminated voltage of high-voltage MOS transistor 44
Examine voltage Vref1)；3rd comparator 473, coupled to controller voltage detecting end VS, for judging high-voltage MOS transistor 44
Whether power port voltage VDS reached the second predeterminated voltage, and (corresponding VS voltage is from high to low through the 3rd reference voltage
Vref3) load voltage VL whether overvoltage thus is indirectly judged.
As it is shown in figure 5, controller 47 also includes: voltage-current converter circuit 483, by the voltage Vcs of current detecting end CS
Be converted to charging current Iq=Vcs/Rq；When OUTN is high, integrating capacitor Cq is discharged, Vton=0；When OUTN is low, Iq
Charge for integrating capacitor 482 (Cq)；Height in the cycle that voltage Vton in integrating capacitor 482 is characterized in a DC voltage Vdc
Pressure MOS transistor 44 passes through high-voltage MOS transistor 44 after turning on the Ton time and is transferred to the quantity of electric charge of output port；Derive permissible
Obtain in the embodiment of the present invention shown in Fig. 4 and Fig. 5, brilliant by high-pressure MOS after the MOS transistor 44 Ton in the conduction state time
The charge Q of body pipe 44 is
As it is shown in figure 5, controller 47 also includes: the second comparator 472, it coupled to integrating capacitor 482 and the second reference electricity
Pressure Vref2；Monopulse generator 474,475 and 476, respectively at first, second, and third comparator output voltage from low to high
A positive pulse is exported during saltus step；Supply voltage VCC clamp circuit 484, for limiting grid (G) electricity of high-voltage MOS transistor
Pressure.
Fig. 6 is the schematic diagram of a kind of rising edge monopulse generator needed for Fig. 5；
Fig. 7 is oscillogram based on the AC-DC converter main node shown in Fig. 4 to Fig. 6 of the present invention；
As shown in Figures 4 to 7, the cycle T of DC voltage Vdc starts to calculate from the crest of alternating voltage Vac.Work as controller
The voltage of 47 voltage detecting end VS is low when crossing Vref3, and the 3rd comparator 473 overturns, and monopulse generator 476 exports positive pulse
Second rest-set flip-flop is set to the 4th state, VL_NORMAL=1 by VDS_HIGH；Voltage as controller 47 voltage detecting end VS
Continue low cross Vref1 time, the first comparator 471 overturns, and monopulse generator 474 exports positive pulse VDS_LOW, by with door
First rest-set flip-flop 478 is set to the second state by 477, and high-voltage MOS transistor 44 turns on；
In conjunction with Fig. 4 to Fig. 7 embodiment it will be seen that after high-voltage MOS transistor 44 enters conducting state, at power port electricity
During pressure VDS is reduced to 0, DC voltage Vdc is load 43 transmission electric charge by high-voltage MOS transistor 44, for output electricity
Hold 42 and supplement electric charge.Period as VDS=0, although high-voltage MOS transistor 44 is in the conduction state, but electric charge does not leads to
Cross high-voltage MOS transistor 44.Due to the periodicity of Vdc, when power port voltage VDS is again more than 0, DC voltage Vdc passes through
High-voltage MOS transistor 44 continues as loading 43 transmission electric charges, supplements electric charge for output capacitance 42.
When high-voltage MOS transistor 44 is in the conduction state, controller 47 detects the electric charge by high-voltage MOS transistor 44
Amount, when in the integrating capacitor 482 coupleding to the second comparator 472 input, voltage Vton is more than Vref2, the second comparator
472 output voltages upset (from low to high), monopulse generator 475 produces positive pulse and the first rest-set flip-flop 478 is set to first
Stable state, is set to three-stable state by the second rest-set flip-flop 479, and high-voltage MOS transistor 44 switches to from conducting state (the second state)
Cut-off state (the first state)；Load average electric current
ILmean=(Vref2/Rcs) * Rq*Cq/T (3)
Wherein T is the cycle of DC voltage Vdc.Therefore, implement Fig. 4 to Fig. 7 embodiment based on the present invention can accurately control
Average output current processed.Can realize high conversion efficiency during for driving light emitting diode, luminosity is not with input AC electricity
Press amplitude fluctuation to change, do not change with the change of LEDs ON voltage.Suitably select bigger output capacitance,
Can effectively reduce output current ripple, reach the effect without ac stroboflash.
Embodiment shown in Fig. 4 to Fig. 7 is used only to illustrate how to realize passing through within a DC voltage cycle
High-voltage switch gear turns on once to the electric charge that Load transportation total amount is preset value Q, is not limited to the present invention.For this area one
As it is obvious to the skilled person that can be implemented in and turned on repeatedly to load by high-voltage switch gear in a DC voltage cycle
Transmission total amount is the electric charge of preset value, reaches the purpose of constant current equally.
When in the embodiment shown in Fig. 4 to Fig. 7, there are the faults such as open circuit in LED load 43, it is undesirable to occur negative
Load voltage VL is too high to such an extent as to punctures the failure modes such as output capacitance 42.As shown in Figure 4, VDS=Vdc-VL, works as DC voltage
When Vdc reaches peak value VdcMax, power port voltage VDS reaches maximum VDSMax=VdcMax-VL.If load voltage mistake
Pressure, such as VL=Vov, VDSMax=VdcMax-Vov will minimize value.Can be by leading for high-voltage MOS transistor 44
Logical one restrictive condition of increase reaches to limit the effect of load voltage: only power end detected in a DC voltage cycle
Mouth voltage VDS is more than just allowing this DC voltage cycle inner high voltage switch 44 from cut-off after the second predeterminated voltage VdcMax-Vov
State switches to conducting state.In a DC voltage cycle, detect that VDS=Vdc-VL is more than VdcMax-Vov, also just anticipate
Taste VdcMax-VL ＞ VdcMax-Vov in the current DC voltage cycle, therefore current DC voltage cycle
VL ＜ Vov (4)
Being the application of 150V for 220V civil power, VL representative value, Vov is 200V, VdcMax-Vov=111V.At Fig. 4 extremely
In embodiment shown in Fig. 7, controller 47 passes through the 3rd reference voltage the most from high to low by detection voltage detecting end VS
Vref3 determines whether formula (4) is set up within the current DC voltage Vdc cycle；It is of course also possible to select by detection voltage detecting
End VS passes through the 3rd reference voltage Vref 3 the most from low to high and determines whether formula (4) becomes within the current DC voltage Vdc cycle
Vertical.
In the embodiment shown in Fig. 4 to Fig. 7, for need not the application of restriction load voltage VL ＜ Vov, (such as VL is relatively
High application), Vref3=Vref1 can be set；Or the 3rd comparator 473 in omission Fig. 5, monopulse generator 476,
Two rest-set flip-flops 479 and with door 477；Divider resistance 46 can also be coupled on output or the alternating voltage of rectifier, logical
Cross detection DC voltage Vdc or alternating voltage Vac, determine that high-voltage MOS transistor 44 switches to conducting state from cut-off state
Moment.
Fig. 8 is the topological structure schematic diagram of the AC-DC converter 50 according to one embodiment of the invention.As shown in Figure 8,
AC-DC converter 50 includes: input port, coupled to alternating voltage Vac；Rectifier 51, coupled to input port, will hand over
Stream voltage Vac is converted to periodic DC voltage Vdc；Output port, to load 53 offer electric current IL and voltage VL；Output electricity
Hold 52, coupled to output port；High-voltage switch gear, is composed in series by high-voltage MOS transistor 54 and low voltage mos transistor 55, high pressure
The source electrode (s) of the drain electrode (D) of MOS transistor and low voltage mos transistor constitutes the power port of high-voltage switch gear, with output capacitance 52
Series connection, coupled to DC voltage Vdc；The control end that grid (g) is high-voltage switch gear of low voltage mos transistor 55；Low pressure MOS crystal
Pipe 55 has the first state (cut-off) and two kinds of duties of the second state (conducting), cut-off state be used for stoping rectifier 51 to
Output capacitance 52 and load 53 transmission electric charge, conducting state is used for allowing rectifier 51 to output capacitance 52 and load 53 transmission electricity
Lotus.
The embodiment of the present invention shown in Fig. 8 also includes: controller 57, has voltage detecting end VS and current detecting end CS
(multiplexing), and output OUT, OUT coupled to the grid (g) of low voltage mos transistor 55；
AC-DC converter 50 shown in Fig. 8 also includes the second storage capacitor 59, coupled to the feeder ear of controller 57
VCC；Second starts resistance 58, coupled to rectifier 51 and the second storage capacitor 59；The DC voltage Vdc of rectifier 51 output leads to
Crossing the second startup resistance 58 is that the second storage capacitor 59 is powered；Second divider resistance 56, coupled to the leakage of low voltage mos transistor 55
End (d) and source (s), the second divider resistance 56 is put for rectifier 51 output and with reference to the parasitic capacitance offer existed between ground
Electric pathway, when DC voltage Vdc is more than load voltage VL, it is ensured that DC voltage Vdc follows alternating voltage Vac change；Second
Divider resistance 56 is for simultaneously for voltage detecting end VS and the current detecting end CS suitable voltage power supply point of offer of controller 57；
Embodiment illustrated in fig. 8 rectifier bridge 51 is full-wave rectification, and alternating voltage Vac is converted to periodic DC voltage
Vdc, the cycle of DC voltage Vdc is the 1/2 of AC-input voltage Vac cycle；High-voltage switch gear and controller are positioned at load 53 Hes
The top of output capacitance 52, for flash control；High-voltage MOS transistor 54 uses source drive, and its grid (G) coupled to controller
The feeder ear VCC of 57；
When the low voltage mos transistor 55 shown in Fig. 8 is in cut-off state, if the drain electrode of high-voltage MOS transistor 54 (D)
To the reference of controller 57 (GND) voltage more than VCC-VT the threshold voltage of high-voltage MOS transistor 54 (VT be), high-pressure MOS
The drain electrode (D) of transistor 54 is limited to source current Ics by divider resistance 56, only microampere magnitude；If high-voltage MOS transistor
The drain electrode (D) of 54 to the reference of controller 57 (GND) voltage less than VCC-VT, (VT is the threshold value electricity of high-voltage MOS transistor 54
Pressure), then high-voltage MOS transistor 54 is operated in linear zone, the drain electrode (D) of high-voltage MOS transistor 54 and the basic phase of source electrode (S) voltage
Deng, the drain-source voltage Vds of low voltage mos transistor reflects from the drain electrode (D) of high-voltage MOS transistor 54 to low voltage mos transistor 55
The port voltage of source electrode (s), the namely power port voltage of embodiment illustrated in fig. 8 high-voltage switch gear.
Therefore, in the embodiment of the present invention shown in Fig. 8, when low voltage mos transistor 55 is in cut-off state, and high pressure
When the drain electrode (D) of MOS transistor 54 arrives the power port voltage of the source electrode (s) of low voltage mos transistor 55 less than VCC-VT, permissible
The port voltage of the VS terminal voltage detecting high-voltage switch gear of the second divider resistance 56 tap it is coupled to by detection；When described second point
When the tap voltage of piezoresistance 56 is less than the first reference voltage Vref 1, controller 57 output OUT voltage is switched to by low level
High level, low voltage mos transistor 55 is switched to conducting state by cut-off state.
In the embodiment of the present invention shown in Fig. 8, when low voltage mos transistor 55 is in the conduction state, high-voltage MOS transistor
54 is in the conduction state, it is allowed to the DC voltage Vdc of rectifier 51 output is to output capacitance and Load transportation electric charge.In Fig. 8 institute
In the embodiment shown, the conducting resistance of low voltage mos transistor 55 plays the effect of current sense resistor, and controller 57 is by multiplexing
Voltage in conducting resistance Rdson of current detecting end CS detection low voltage mos transistor 55, is converted into integration after electric current,
Obtain the quantity of electric charge by high-voltage MOS transistor 54, when the described quantity of electric charge reaches the first preset value Q by low voltage mos transistor
55 switch to by state from conducting state.
In the embodiment shown in fig. 8, the schematic diagram of controller 57 is still as shown in Fig. 5 Fig. 6, only by the 3rd with reference to electricity
Pressure Vref3 is set to equal with the first reference voltage Vref 1.
In the embodiment shown in fig. 8, when low voltage mos transistor 55 is in the conduction state, its conducting resistance Rdson is made
Use for current sense resistor, decrease the parts number of AC-DC converter, reduce cost.Certainly, current sense resistor
Can also realize with a single resistance, current detecting end CS coupled to described independent detection resistance, voltage detecting end VS
It coupled to the drain electrode of low voltage mos transistor, not with current detecting end CS multiplexing.
Fig. 9 is oscillogram based on AC-DC converter main node shown in embodiment of the present invention Fig. 8.Fig. 8 controls
The circuit theory diagrams of device 57 are as shown in Figure 5 and Figure 6.As it is shown in figure 9, from the crest (or trough) of input ac voltage Vac
Start to calculate the cycle of DC voltage Vdc.When high-voltage switch gear power port voltage (Vdc-VL) is more than VCC-VT, VS/CS electricity
Pressure is clamped, and controller 57 cannot detect the power port voltage of high-voltage switch gear；As high-voltage switch gear power port voltage (Vdc-
VL) time less than VCC-VT, VS/CS voltage reflection high-voltage switch gear power port voltage.When VS/CS voltage is less than Vref1, positive arteries and veins
Rush VDS_HIGH and VDS_LOW to occur simultaneously, produce positive pulse SW_ON OUT is set to high level, low voltage mos transistor 55 by
Cut-off state switches to conducting state, occurs from DC voltage Vdc to output capacitance 52 and the charge transfer process of load 53,
Ics electric current is more than zero.When high-voltage switch gear power port voltage (Vdc-VL) is equal to 0, although low voltage mos transistor 55 is still located
In conducting state, but the electric charge not from DC voltage Vdc passes through high-voltage switch gear, and Ics electric current is zero.Work as high-voltage switch gear
When power port voltage (Vdc-VL) is more than 0, charge transfer occurs again, and Ics electric current is more than zero.When integration electricity in controller 57
When voltage VTon in appearance is more than Vref2, the total amount of charge transfer reaches preset value Q, the second comparator output terminal saltus step, produces
OUT is set to low level by positive pulse SW_OFF, and low voltage mos transistor 55 switches to cut-off state from conducting state.Due to Fig. 8 extremely
The embodiment of the present invention shown in Fig. 9 uses full-wave rectification, and the cycle of DC voltage Vdc is equal to the 1/2 of alternating voltage Vac cycle T,
Average load current
ILmean=2* (Vref2/Rcs) * Rq*Cq/T (5)
Therefore, embodiment based on Fig. 8 to Fig. 9 of the present invention can accurately control average output current.When sending out for driving
Luminosity can be realized during optical diode do not change, the most not with LEDs ON with input ac voltage amplitude fluctuation
The change of voltage and change.Suitably select the capacitance of output capacitance, can effectively reduce output current ripple, reach without exchange frequency
The effect dodged.
Figure 10 is the side of a kind of AC-DC converter with constant average output current according to the embodiment of the present invention
Method flow process Figure 60.As shown in Figure 10, described method includes:
Step 61, input ac voltage；
Step 62, is periodicity DC voltage by ac voltage rectifier；
Step 63, waits that a DC voltage cycle starts；
Step 64, it is judged that whether DC voltage adds predeterminated voltage less than load voltage: if described DC voltage is less than load
Voltage adds predeterminated voltage, enters step 65；If described DC voltage adds predeterminated voltage more than load voltage, continue step 64；
Step 65, transmits electric charge from described DC voltage to output port；
Step 66, it is judged that whether charge transfer amount reaches preset value: if charge transfer amount reaches preset value, enter step
63；If charge transfer amount is not reaching to preset value, enter step 65.
Although several exemplary embodiment describing the present invention according to above-mentioned, it should be appreciated that, term used is
Illustrate and exemplary rather than restrictive term.Owing to the present invention can be embodied as in a variety of forms without deviating from this
The spirit of invention or essence, it should therefore be appreciated that above-described embodiment is not limited to any foregoing detail, and should
Understand widely in the spirit and scope that claim is limited.Therefore, fall in claim or its equivalent scope is complete
Portion's change and remodeling are all contained by claim.
Claims (18)
1. an AC-DC converter, it is characterised in that described AC-DC converter includes:
Input port, coupled to alternating voltage；
Rectifier, coupled to input port, and alternating voltage is converted to periodically DC voltage；
Output port, provides electric current and voltage to load；
Output capacitance, coupled to output port；
High-voltage switch gear, is coupled in series to rectifier with output capacitance；Described high-voltage switch gear has power port and controls end, work
In the first state and the second state, when high-voltage switch gear is in the first state, described high-voltage switch gear stops rectifier to output
Port transmission electric charge, when high-voltage switch gear is in the second state, described high-voltage switch gear allows rectifier to transmit electric charge to output port；
Controller, has voltage detecting end and the current detecting end of output, independence or multiplexing, coupled to high-voltage switch gear；Described
By the power port voltage of voltage detecting end detection high-voltage switch gear, controller determines that described high-voltage switch gear switches from the first state
Being the moment of the second state, described controller is detected when described high-voltage switch gear is in the second state by current detecting end and passes through height
The quantity of electric charge compressed switch, determines that high-voltage switch gear switches to the moment of the first state from the second state；
2. AC-DC converter as claimed in claim 1, it is characterised in that described controller is at described DC voltage
The power port voltage of described high-voltage switch gear is detected, when described high-voltage switch gear power port voltage is less than first in each cycle
During predeterminated voltage, high-voltage switch gear is switched to the second state from the first state by controller, when described high-voltage switch gear is in the second state
Time, when by the quantity of electric charge of described high-voltage switch gear reach first preset the quantity of electric charge time described controller by high-voltage switch gear from the second shape
State switches to the first state；
3. AC-DC converter as claimed in claim 1, it is characterised in that described controller is at described DC voltage
The power port voltage of described high-voltage switch gear is detected, when the power port voltage described high-voltage switch gear being detected in each cycle
After the second predeterminated voltage, when described high-voltage switch gear power port voltage is less than the first predeterminated voltage, controller is by high pressure
Switch switches to the second state from the first state, when described high-voltage switch gear is in the second state, when by described high-voltage switch gear
The quantity of electric charge reach the first described controller when presetting the quantity of electric charge high-voltage switch gear switched to the first state from the second state；
4. AC-DC converter as claimed in claim 1, it is characterised in that farther include the first divider resistance, coupling
To described high-voltage switch gear power port, the voltage detecting end of the tap coupler of described first divider resistance to described controller；
5. AC-DC converter as claimed in claim 1, it is characterised in that farther include current sense resistor, series connection
Coupleding to described high-voltage switch gear power port, described current sense resistor is also coupled to described controller current detecting end；
6. AC-DC converter as claimed in claim 2, it is characterised in that described controller includes the first bistable electro
Road, has the first stable state and the second stable state, the first state of corresponding described high-voltage switch gear and the second state；When described controller electricity
When pressure test side voltage is less than the first reference voltage, described first bistable circuit switches to the second stable state from the first stable state；When
Under second stable state by the quantity of electric charge of described high-voltage switch gear reach first preset the quantity of electric charge time, described first bistable circuit is from
Two stable states switch to the first stable state；Under above-mentioned mode of operation, the average current that the output of described AC-DC converter is constant；
7. AC-DC converter as claimed in claim 3, it is characterised in that described controller includes the first bistable electro
Road, has the first stable state and the second stable state, the first state of corresponding described high-voltage switch gear and the second state；Described controller also wraps
Include the second bistable circuit, there is three-stable state and the 4th stable state；When described controller voltage detecting terminal voltage from high to low or
When passing through three reference voltages from low to high, described second bistable circuit switches to the 4th stable state from three-stable state；When described
When controller voltage detecting terminal voltage is in four stable states less than the first reference voltage and described second bistable circuit, described
First bistable circuit switches to the second stable state from the first stable state, when being reached by the quantity of electric charge of described high-voltage switch gear under the second stable state
To first preset the quantity of electric charge time, described first bistable circuit switches to the first stable state, described second bistable state from the second stable state
Circuit switches to three-stable state from the 4th stable state；Under above-mentioned mode of operation, described AC-DC converter is low at output voltage
Constant average current is exported under conditions of the second predeterminated voltage；
8. the AC-DC converter as described in claim 6 or claim 7, it is characterised in that described controller includes
One comparator, coupled to described controller voltage detecting end, when the voltage of described controller voltage detecting end is less than the first reference
First comparator output level upset described in during voltage, drives a monopulse generator to produce a single pulse signal；
9. the AC-DC converter as described in claim 6 or claim 7, it is characterised in that described controller includes electricity
Piezo-electric stream change-over circuit, integrating capacitor and the second comparator, the input of described current/charge-voltage convertor coupled to described
Controller current detecting end, it is described integration electricity that the voltage that described controller current detecting end detects is converted to integration current
Capacity charge, the voltage in described integrating capacitor characterizes the quantity of electric charge by described high-voltage switch gear, the electricity in described integrating capacitor
When pressure reaches the second reference voltage, described second comparator output level upset, described first bistable circuit is set to first
Stable state, is set to three-stable state by described second bistable circuit；
10. AC-DC converter as claimed in claim 9, it is characterised in that described controller includes discharge switch, coupling
It is bonded to described integrating capacitor；And first reverse inter-delay-ing circuit, it coupled to described controller output end and described discharge switch, institute
Stating the first reverse inter-delay-ing circuit by described controller output signal time delay and to negate, controlling discharge switch is that described integrating capacitor is pre-
Put initial state voltage；
11. AC-DC converters as claimed in claim 7, it is characterised in that described controller includes the 3rd comparator,
It coupled to described controller voltage detecting end, when the voltage of described controller voltage detecting end passes through from high to low or from low to high
During three reference voltages, described 3rd comparator output level upset, described second bistable circuit is set to the 4th stable state；
12. AC-DC converters as described in claim 1 to claim 3, it is characterised in that described high-voltage switch gear is
Three end high-voltage MOS transistors, described controller output end coupled to the grid of described high-voltage MOS transistor, described first dividing potential drop
Resistance coupled to drain electrode and the source electrode of described high-voltage MOS transistor, described first divider resistance tap coupler to described controller
Voltage detecting end, described current sense resistor coupled to the source electrode of described high-voltage MOS transistor and the reference ground of described controller,
The source electrode of described high-voltage MOS transistor coupled to the current detecting end of described controller；
13. AC-DC converters as claimed in claim 1, it is characterised in that described high-voltage switch gear is by a high-pressure MOS
Transistor and a low voltage mos transistor are composed in series, and it is brilliant that the source electrode of described high-voltage MOS transistor coupled to described low pressure MOS
The drain electrode of body pipe, the grid of described high-voltage MOS transistor coupled to the first voltage source, the grid coupling of described low voltage mos transistor
It is bonded to the output of described controller；
14. AC-DC converters as claimed in claim 13, it is characterised in that described AC-DC converter includes
Two divider resistances, coupled to drain electrode and the source electrode of described low voltage mos transistor；
15. AC-DC converters as described in claim 2 and claim 13 or claim 14, it is characterised in that institute
The voltage detecting end stating controller coupled to the drain electrode of described low voltage mos transistor, when described low voltage mos transistor is in cut-off
State and the drain-source voltage of described low voltage mos transistor are less than described first voltage source and described high-voltage MOS transistor threshold value
During difference in voltage, described high-voltage MOS transistor is operated in linear zone, and the drain-source voltage of high-voltage MOS transistor is approximately zero, described
The drain-source voltage of low voltage mos transistor characterizes the power port voltage of described high-voltage switch gear；When described low voltage mos transistor drain-source
When the power port voltage of the high-voltage switch gear that voltage is characterized is less than the first predeterminated voltage, described controller is by described low pressure MOS
Transistor switches to conducting state from by state；
16. AC-DC converters as claimed in claim 15, it is characterised in that the current detecting end coupling of described controller
It is bonded to the drain electrode of described low voltage mos transistor, when described low voltage mos transistor is in the conduction state, described low pressure MOS crystal
The conducting resistance of pipe plays the effect of current sense resistor, and described high pressure is flow through in the drain-source voltage reflection of described low voltage mos transistor
The electric current of MOS transistor, flows through the electric current of described high-voltage MOS transistor when described low voltage mos transistor is in the conduction state
The integrated value of time reaches the first described controller when presetting the quantity of electric charge switched from conducting state by described low voltage mos transistor
For by state；
17. AC-DC converters as claimed in claim 13, it is characterised in that described first voltage source includes the first storage
Energy electric capacity, coupled to the feeder ear of described controller, and first starts resistance, coupled to described rectifier, the first voltage clamping electricity
Road, coupled to the feeder ear of described controller and with reference to ground；
18. 1 kinds of methods for AC-DC converter, including:
It is periodic DC voltage by ac voltage rectifier；
Wait that a DC voltage cycle starts；
Judge whether described DC voltage adds predeterminated voltage less than output voltage, if described DC voltage adds less than output voltage
Predeterminated voltage, starts to transmit electric charge from described DC voltage to output port, when transmitting the quantity of electric charge and reaching preset value, terminates electricity
Lotus is transmitted, and waits that the next DC voltage cycle starts；If described DC voltage adds predeterminated voltage higher than output voltage, wait
Described DC voltage step-down；
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|---|---|---|---|
| CN201510078564.1A CN105897009A (en) | 2015-02-13 | 2015-02-13 | AC-DC converter and method thereof |
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| CN201510078564.1A CN105897009A (en) | 2015-02-13 | 2015-02-13 | AC-DC converter and method thereof |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108024031A (en) * | 2016-10-28 | 2018-05-11 | 福州瑞芯微电子股份有限公司 | The direct current restoration methods and device of a kind of AC signal |
| CN108279728A (en) * | 2018-04-08 | 2018-07-13 | 深圳市必易微电子有限公司 | Exchange turns direct current linear voltage-stabilizing circuit |
| CN108418427A (en) * | 2018-02-13 | 2018-08-17 | 昂宝电子（上海）有限公司 | System and method for one or more of regulation power converter threshold value |
| CN108631617A (en) * | 2017-03-20 | 2018-10-09 | 万国半导体(开曼)股份有限公司 | Hard switching for switching power source device disables |
| CN112771781A (en) * | 2018-07-10 | 2021-05-07 | 纬湃科技有限责任公司 | Control method of transistor driving module |
| CN117439381A (en) * | 2023-12-21 | 2024-01-23 | 拓尔微电子股份有限公司 | Function multiplexing circuit and DC-DC converter |
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- 2015-02-13 CN CN201510078564.1A patent/CN105897009A/en active Pending
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108024031A (en) * | 2016-10-28 | 2018-05-11 | 福州瑞芯微电子股份有限公司 | The direct current restoration methods and device of a kind of AC signal |
| CN108024031B (en) * | 2016-10-28 | 2019-10-29 | 福州瑞芯微电子股份有限公司 | A kind of the direct current restoration methods and device of AC signal |
| CN108631617A (en) * | 2017-03-20 | 2018-10-09 | 万国半导体(开曼)股份有限公司 | Hard switching for switching power source device disables |
| CN108631617B (en) * | 2017-03-20 | 2020-06-16 | 万国半导体(开曼)股份有限公司 | Hard switch disabling for switching power supply devices |
| CN108418427A (en) * | 2018-02-13 | 2018-08-17 | 昂宝电子（上海）有限公司 | System and method for one or more of regulation power converter threshold value |
| CN108418427B (en) * | 2018-02-13 | 2020-07-14 | 昂宝电子（上海）有限公司 | System and method for adjusting one or more thresholds in a power converter |
| CN108279728A (en) * | 2018-04-08 | 2018-07-13 | 深圳市必易微电子有限公司 | Exchange turns direct current linear voltage-stabilizing circuit |
| CN112771781A (en) * | 2018-07-10 | 2021-05-07 | 纬湃科技有限责任公司 | Control method of transistor driving module |
| CN117439381A (en) * | 2023-12-21 | 2024-01-23 | 拓尔微电子股份有限公司 | Function multiplexing circuit and DC-DC converter |
| CN117439381B (en) * | 2023-12-21 | 2024-02-23 | 拓尔微电子股份有限公司 | Function multiplexing circuit and DC-DC converter |
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Application publication date: 20160824 |